Internal-combustion engines – Lubricators – Crankcase – pressure control
Reexamination Certificate
1999-07-14
2001-04-24
Kamen, Noah P. (Department: 3747)
Internal-combustion engines
Lubricators
Crankcase, pressure control
C184S006800, C184S013100
Reexamination Certificate
active
06220216
ABSTRACT:
BACKGROUND OF THE INVENTION
In reciprocating internal combustion engines, a piston is guided for longitudinal movement in a cylinder and the piston drives a crankshaft via a connecting rod. The crankshaft is rotatably journalled in a crankcase which contains lubricating oil for the crank drive. The connecting rod is pivotally held on a crankpin arranged eccentrically to the rotational axis of the crankshaft.
If such a reciprocating engine is utilized in a portable handheld work apparatus such as a motor-driven chain saw or the like to drive the work tool, then the engine is regularly moved out of its stand up normal alignment when, for example, the work tool and therefore the drive motor are guided sideways or even overhead. Without suitable countermeasures, the lubricating oil flows in the direction of the piston and can enter the combustion chamber. This can effect the proper operation of the engine especially when the apparatus is put down at engine standstill in the overhead position of the engine. It is even possible that lubricating oil drips out of the engine.
German patent publication 197 38 155 discloses a four-stroke internal combustion engine having a chamber next to the cylinder and which chamber contains lubricating oil. The chamber is configured as an oil receptacle with baffle walls within the crankcase in which the lubricating oil is taken up when the cylinder is in an overhead position. An oil catcher is movable with the crankpin about the rotational axis of the crankshaft and projects into the chamber containing the lubricating oil. The oil catcher is intended to catch lubricating oil and spray the lubricating oil onto the components to be lubricated at high rpm of the crankshaft.
In the known engine, the crankcase is configured to have a double wall. The inner baffle wall encloses the components of the crank drive and the outer wall of the crankcase surrounds the inner wall. The space, which is formed between the baffle wall and the outer wall, holds the lubricating oil for the crank drive. A slot is formed in the baffle wall and extends on the side of the baffle wall in the peripheral direction. This side of the baffle wall lies opposite the piston. The oil catcher projects through the slot into the chamber containing the lubricating oil and the oil bath contained therein.
The outer wall of the lubricating oil chamber is connected to the inner wall above the crankshaft, that is, on the side facing toward the cylinder whereby an oil catch is formed. In the side position and in the overhead position, the oil catch holds the lubricating oil, which flows in the direction of the cylinder, back into the oil chamber. The crank chamber, which is closed off by the baffle wall, is thereby separated from the lubricating oil chamber whereby a wetting of the backside of the piston is precluded in a position of the engine deviating from the normal alignment. The oil catcher is configured radially on the crankpin but enters only segmentwise through the slot into the oil chamber during its revolution and therefore can only catch lubricating oil and move the same to the crank drive when the engine is in its upright position and the lubricating oil is disposed at the base of the lubricating chamber and accessible for the oil catcher. Although the oil is prevented from entering into the crank chamber in the overhead position of the engine, a lubrication is, however, no longer provided so that operating disturbances of the engine can occur very quickly.
SUMMARY OF THE INVENTION
It is an object of the invention to improve a reciprocating piston engine in such a manner that an adequate lubrication of the movable components is ensured in every operating position of the reciprocating piston engine.
The reciprocating internal combustion engine of the invention includes: a cylinder defining a longitudinal axis and having a cylinder wall; a piston guided to move longitudinally in the cylinder; a crankcase connected to the cylinder; a crankshaft rotatably journalled in the crankcase and defining a rotational axis; a crank drive including a crankpin operatively connected to the crankshaft and the crankpin being arranged eccentrically to the rotational axis; a connecting rod pivotally connected to the crankpin; the piston being connected to the connecting rod for imparting rotational movement to the crankshaft via the crankpin; the crankcase having a crankcase wall defining an interior space and having a first end configured as a sump for holding lubricating oil in a first spatial orientation of the engine; the crankcase having a second end in the region of the cylinder; the cylinder being connected to the crankcase so as to cause the cylinder wall to extend axially into the interior space at the second end of the crankcase; and, the cylinder wall and the crankcase wall conjointly defining a receptacle for catching oil at the second end of the crankcase in a second spatial orientation of the engine.
The crankcase is configured so as to have a trough-like shape and contains the lubricating oil. The cylinder projects axially into the crankcase and forms a wall of the oil receptacle with its outer wall surface. The cylinder and the crankcase are thereby axially pushed one inside the other whereby the space that the piston engine occupies is reduced. The oil receptacle is defined by the crankcase wall and the inwardly projecting wall of the cylinder outside of the region of movement of the crank drive. In this oil receptacle, the lubricating oil collects in the overhead position of the reciprocating piston engine. The oil receptacle is open toward the crank chamber and the crank drive disposed therein whereby the lubricating oil is held in movement by the crank drive also in positions deviating from the upright position of the crankcase. If the reciprocating piston engine is tilted and brought into the overhead position, then the sump oil is lifted from the housing base and caught by the crank drive.
The lubrication and formation of a lubricating oil mist by the crank drive can be augmented by an oil catcher which is movable about the rotational axis with the crankpin and projects into the interior space of the crankcase. For every revolution, a partial volume of the lubricating oil is caught by the oil catcher and sprayed onto the crank drive parts in the crank chamber which are to be lubricated. The oil catcher reaches into the oil receptacle and thereby catches large amounts of the lubricating oil which have collected in the oil receptacle in side and overhead positions of the reciprocating piston engine.
The oil catcher, which rotates about the rotational axis of the crankshaft, either catches the sump oil located at the base in the normal position or the lubricating oil collected in the oil receptacle in the overhead position independently of the alignment of the piston reciprocating engine. Advantageously, the oil catcher is mounted on an end face of a radial crank web of the crankshaft lying opposite the crankpin. The oil catcher is mounted eccentrically to the rotational axis and extends radially into the oil receptacle. The oil catcher rotates freely in the crankcase with the crank web. Preferably, crank webs are mounted on both sides of the crankpin and each crank web is provided with an oil catcher whereby the lubricating capacity is overall increased and is doubled in the overhead operation. Even in the lateral positions of the reciprocating piston engine, the lubrication can always be maintained.
The crankcase can advantageously be configured symmetrically to the longitudinal axis of the cylinder and, in this way, the oil receptacle can be configured to have an annular shape about the cylinder. Advantageously, the cylinder is placed with a radial flange on a flange of the crankcase whereby the cylinder wall projects into the crankcase in the built-in position of the cylinder. The radial flange is configured so as to be axially spaced from where the cylinder opens to the crankcase. The interface plane of the cylinder flange and of the crankcase flange purposefully lies orthogon
Andreas Stihl AG & Co.
Kamen Noah P.
Ottesen Walter
LandOfFree
Four-stroke reciprocating internal combustion engine does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Four-stroke reciprocating internal combustion engine, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Four-stroke reciprocating internal combustion engine will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2550345