Metal working – Method of mechanical manufacture – Prime mover or fluid pump making
Reexamination Certificate
2000-10-20
2002-04-02
Echols, P. W. (Department: 3726)
Metal working
Method of mechanical manufacture
Prime mover or fluid pump making
C029S006010, C029S464000, C029S468000, C029S281300, C029S281500
Reexamination Certificate
active
06363609
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method and apparatus for aligning crankshaft sections and, more particularly, to a method and apparatus for the high-precision phasing of crankshaft sections during the manufacture or reassembling of pressed-together multi-cylinder engine crankshafts. Specifically, the invention relates to a novel technique and tool for aligning the center sections of pressed-together crankshafts used in personal motorized watercraft and snowmobile engines.
BACKGROUND OF THE INVENTION
Crankshafts for precision machines must be accurately manufactured, or reassembled, to properly drive the engine components of the machines of which they are part. Methods and tools used in the manufacture of crankshafts are described in U.S. Pat. Nos. 4,979,335, 5,625,945 and 5,984,599. A most important aspect of such accurate manufacturing or reassembling is the alignment of the crankshaft sections. A crankshaft section usually comprises two “journals”, connected by a center pin, and one or more associated bearings. A “journal” is an annular disc, or “web”, with a peripheral pin transversely attached to it. Proper alignment of the crankshaft sections is particularly critical when the crankshaft sections are center sections of “pressed-together crankshafts”, that is, crankshafts where the connecting center pins of at least some of the sections are press fit to one or both of the journals to which they are connected. Press fitting is the assembling of any two machined pieces by creating a bond between them as a result of the fact that one of them has been inserted within the other, so as to be properly in place, by the use of force. For example, a round connecting center pin may be press fit to a journal by providing, in the journal, an orifice with a diameter between 0.0002 and 0.004 inches smaller than the diameter of the pin, and forcing the pin into the orifice by mechanical exertion. Pressed-together crankshafts are built and reassembled by manufacturers and rebuilders such as Kawasaki, Polaris, Yamaha and others for combustion engines with several cylinders and, in particular, for combustion engines for personal motorized watercrafts, snowmobiles and similar vehicles. In contrast to pressed-together crankshafts, “single-piece crankshafts” are designed so that the journals and connecting center pins of their sections form one solid single piece, and the crankshafts themselves are usually forged in one piece. As a result, the crankshaft sections of single-piece crankshafts normally remain aligned so long as the main shaft is not accidentally bent. The crankshaft sections of pressed-together crankshafts, on the other hand, exhibit a tendency to fall out of phase during operation and as a result of normal tear and wear due to extended use. When this happens, the engines do not operate properly, or simply stop running, and they have to be taken apart so that the crankshaft sections may be properly aligned. Also, crankshafts often have to be taken apart to replace defective bearings and perform repairs or maintenance. When taken apart, the crankshaft sections usually fall out of phase and have to be re-aligned. Since crankshaft sections usually include two journals, the alignment of crankshaft sections is sometimes also referred to as the “alignment of crankshaft journals”. Conventional crankshaft alignment techniques can be cumbersome and time-consuming, and add substantial costs to the building and reassembling of crankshafts, particularly when the crankshafts are pressed-together crankshafts. It is apparent that a need exists, then, to provide a technique and a tool for properly and quickly aligning crankshaft sections, and, in particular, for properly and quickly aligning crankshaft sections of pressed-together crankshafts in minimum time and with minimum expense.
SUMMARY OF THE INVENTION
An object of this invention is to provide a technique and a tool for accurately aligning crankshaft sections. An object of the instant invention is also to provide a method and an apparatus for accurately and rapidly aligning pressed-together crankshaft sections, which method and apparatus may be used on practically all kinds of pressed-together crankshafts regardless of their make or origin. Another object of the invention is to provide an inexpensive method and apparatus for properly aligning the crankshaft sections normally found in the multiple-cylinder combustion engines used in personal motorized watercrafts and snowmobiles. A further object of this invention is to provide a method and a tool for the accurate, rapid and inexpensive alignment of said crankshaft sections that can be used and operated by essentially one operator with minimum amount of training. These and other objects of the invention will become apparent from the disclosure that follows.
The above objects are achieved by the phasing station tool and method of the instant invention. When used properly and in accordance with the method disclosed herein, the phasing station of this invention allows one single operator to accurately align and assemble pressed-together crankshaft sections and provide the desired degree of orientation in minimum time and with minimum expense.
The phasing station of this invention comprises a housing (also referred to as a “die shoe”), a phasing fixture (also referred to as a “phasing jig”), and crankshaft spacing means (also referred to as a “spacing tool”). The housing (die shoe) comprises two rigid plates, mounted in parallel fashion with respect to each other, preferably one above the other, and a plurality of linear bearing sets, mounted in perpendicular fashion with respect to the two rigid plates and in parallel fashion with respect to each other. The two rigid plates are preferably made of steel, and, for convenience, are referred to in this description as the “upper plate” and the “lower plate”. The linear bearing sets are preferably sets of hollow tubular members, concentrically mounted with respect to each other. The inner tubular members of the linear bearing sets are attached to the lower plate; the outer tubular members of the, linear bearing sets are attached to the upper plate and have a slightly larger diameter than the inner tubular members. Preferably, the upper plate has several perforations (holes) on its surface, spaced out and of such shapes and sizes as to allow for a press fit of the outer tubular members of the linear bearing sets; and, preferably, the lower plate has several perforations (holes) on its surface, spaced out and of such shapes and sizes as to allow for a press fit of the inner tubular members of the linear bearing sets. The upper plate of the die shoe is also provided with means for attaching a hydraulic actuator assembly to its surface so as to allow a hydraulic actuator to apply pressure to and move the upper plate towards to and away from the lower plate of the die shoe. The upper, plate also has at least two, preferably threaded, perforations for bolting or otherwise securing the upper portion of the phasing jig to the plate. The lower plate has multiple perforations for receiving the alignment dowel pins of the machined steel cylinder of the lower portion of the phasing jig and locking it into different positions, as described below.
The phasing fixture (phasing jig) consists of two substantially identical metal portions so attached or placed within the phasing station as to face each other in virtual image formation: one from the upper plate of the die shoe and the other one from the lower plate. Each such substantially identical metal portion comprises a machined steel cylinder, a phasing tool and a phasing tool lock down. In addition, the lower portion of the phasing jig also comprises a centering tool and a centering tool lock down. The following is a description of the lower portion of the phasing jig, which is attachable to the lower plate. It should be understood that, except for the fact that it does not have alignment dowel pins, an orifice for mounting a centering tool, a centering tool or a centering tool lock dow
Compton Eric
Echols P. W.
Fonte Raúl V.
Short Block Technologies, Inc.
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