Method of making a carbon composite piston engine crankshaft

Abstract

A piston engine crankshaft made from carbon composite material molded in two separate moldings is disclosed. According to a preferred embodiment, the first mold is optimized to for the top dead center piston ignition load. The second molding takes the dynamic piston and rod load and contains the counterweight. Accordingly, carbon fiber filaments are aligned in preferred directions to ideally absorb loads at different areas of the crankshaft.

Claims

1. A method for making a carbon composite crankshaft, the method comprising: providing a 1.sup.st mold, for manufacturing a main shaft portion; laying up a multiplicity of carbon composite filaments substantially parallel to an axis of rotation of the main shaft portion in the 1.sup.st mold; molding a counterweight portion with a 2.sup.nd mold wherein carbon composite filaments are arranged substantially in a plane perpendicular to the axis of rotation of the main shaft, to exclude directions outside the plane perpendicular to the axis, providing material strength in light of operational stresses to the counterweight; and bonding the counterweight portion to the main shaft portion using additional filaments and a resin.

2. The method for making a carbon composite crankshaft of claim 1, wherein the bonding of the counterweight portion to the main shaft portion using additional filaments and a resin comprises employing an elongated carbon fiber filament over the main shaft portion.

3. The method for making a carbon composite crankshaft of claim 1, wherein the molding a counterweight portion with a 2.sup.nd mold comprises laying up an additional multiplicity of carbon fiber filaments in substantially all directions in an y-z plane.

4. The method for making a carbon composite crankshaft of claim 1 further comprising inserting an inflatable bladder to the 1.sup.st mold for manufacturing a hollow crankshaft.

5. The method for making a carbon composite crankshaft of claim 1 further comprising inserting a heavy inert material to the 2.sup.nd mold providing counter balance to the crankshaft.

6. The method for making a carbon composite crankshaft of claim 1, wherein the resin is an epoxy.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The novel features of this invention, as well as the invention itself, both as to its structure and its operation, will be best understood from the accompanying drawings, taken in conjunction with the accompanying description, in which similar reference characters refer to similar parts, and in which:

(2) FIG. 1 is a rendering of a crankshaft counter weight coupled to a main shaft portion;

(3) FIG. 2 is an overhead sectional illustration of a main crankshaft portion of the present invention having a counterweight affixed thereto;

(4) FIG. 3A is a schematic side view of one half of a preferred crankshaft for a one cylinder or multi-cylinder engine;

(5) FIG. 3B is an additional side view of a first mold cavity for the piston loading portion of the crankshaft;

(6) FIG. 3C is illustrative of a second mold cavity that comprises the piston and rod counterweight as adhered to the crankshaft;

(7) FIG. 4A is a schematic view of a hollow wall of a main crankshaft; and

(8) FIG. 4B is a schematic axial view of the hollow wall of the main crankshaft approximately along line 4B-4B in FIG. 2.

DESCRIPTION OF PREFERRED EMBODIMENTS

(9) With regard to FIG. 1 a portion of a crankshaft 11 for coupling to a piston cylinder arrangement is shown with particular attention to a counter weight 30 element. As stated, the invention in a first aspect is a carbon fiber piston engine crankshaft; but further made from two molds. According to various embodiments 10 herein, a first mold 20 (FIG. 3B) constructs the crankshaft using a series of carbon fiber 41 composite lay ups continuously formed on top of one another. A second mold in turn constructs the counterweight 30. Importantly in the second mold, fibers 42, 43 are aligned perpendicular to the crankshaft axis of rotation 99, also corresponding to an x-axis herein. Particularly, relatively shorter fibers 42 in the second counterweight mold are perpendicular to the x-axis in a y-z plane. Alternatively, fibers 42 in the counterweight 30 mold 20 are in all directions in the y-z plane. Also according to the invention, the fibers 42, 43 in the second mold are exclusive to the y-z plane. Still further, an elongated fiber 43 wraps around what is to be the crankshaft 11 in the counterweight mold. An elongated fiber 43 may be defined as having a length twenty or more times as long as compared to its diameter.

(10) With regard to FIG. 2 together with FIG. 1, rod bearing 12 and crankshaft bearing 13 are illustrated, the former configured to a connecting rod 14. An inflatable bladder 15 may further be inserted to the first crankshaft mold 20 to provide a hollow configuration to the molding process; the hollow side walls 11 are also illustrated in FIG. 4A and FIG. 4B.

(11) With regard to FIG. 3A, the invention in a first aspect is a carbon composite piston engine crankshaft 10 made in two separate moldings (FIG. 3B and FIG. 3C). The first molding 20 takes the piston ignition loading. In other words, the stresses the expanding cylinder imparts on the crankshaft 11 at top dead center. The second molding takes the piston and rod dynamic loading and contains their counterweight 30. The mold material carrying complex loading is a high modulus composite material which can be made in many ways. The bearing and lubrication requirements of the carbon composite crankshaft 11 are similar to steel crankshafts.

(12) Further with regard to FIG. 3A through FIG. 3C, the invention 10 is a method for making a carbon fiber piston engine crankshaft 10, 11 initially using a first mold 20 followed by molding a counterweight 30 from a second mold. Subsequently, the invention includes the step of bonding the counterweight 30 to the crankshaft 11. The invention 10 in this aspect is additionally characterized as aligning (or laying-up) a plurality of carbon matrix filaments 41 in a longitudinal direction with respect to the crankshaft 11, or the crankshaft 11 having an axis of rotation 99 (or x-axis, FIG. 2). A second mold has a unique lay-up 42 optimized for centrifugal loads as these loads are more problematic than the piston loads at 5,000 rpm. The counterweight 30 made from the second mold is more specifically bonded to the main shaft 11 with a matrix having a plurality of elongated filaments 43 that wrap around the first lay-up main shaft.

(13) Also with regard to FIG. 3A, a portion of an exemplary crankshaft having a counterweight 11 is shown. FIG. 3B illustrates the first mold 20, about a center line (CL), designed to absorb piston loads without brittle fracture. Rod bearing 12 and crankshaft bearing 13 are further integrated to the carbon composite crankshaft and are comprised of softer material, such as lead, that can support the spinning crankshaft with proper wear properties.

(14) Also, importantly in the process to reduce weight, an inflatable bladder 15 is inserted into a mold cavity and thereby forming a crankshaft 11 having hollow portions further reducing weight thereof without sacrificing strength. Interior side walls are illustrated in FIG. 3A, FIG. 3B and FIG. 3C with lines outlining a hollow interior.

(15) FIG. 3C illustrates a second molding for making a piston and rod counterweight 30. The second mold allows for material fibers having high modulus to be loaded in a different geometry, or lay-up, or filament density, optimized for its different loading as compared to the shaft piston loading. A heavy inert material 31 is additionally inserted to the counterweight 30 mold in the molding process. Still further, inert material 31 may be recycled after useful engine life. Fully manufactured, the carbon composite piston engine,

(16) In still an additional embodiment, the invention is a carbon composite crankshaft 10 that is oil cooled with forced convention using two different oil pumps. As stated, the carbon composite will peak in structural performance at 180 degrees and rapidly decline at even higher temperatures. Ideally, the crankshaft 10 is maintained at just over 150 degrees which is problematic since the oil coming off the combustion chamber area is much hotter.

(17) Also of concern, piston engines with one oil pump are often over used. This is because the engine is able to spin past peak load so the pump is set at the higher load. But however, a vehicle piston engine will typically operate primarily under peak. Hence according to the invention, two oil lubrication and cooling pumps are provided wherein a first is run at or under peak and the second pump supplements after peak, which facilitates engine longevity and wear. Also according to this embodiment, the first pump is configured to begin lubrication just before start-up which provides pre-oil to the engine particularly increasing its lifetime. Therefore further, the invention comprises an engine oil system having two pumps configured with a separator that keeps the top oil and crankcase separated until they enter the oil cooler. Additionally, as an example for keeping the crankcase cool, a first oil pump will start prior to engine ignition. A second pump has a start up trip point of high RPM; and hence increases the life of both pumps and not providing more cooling than necessary.

(18) It should be understood, of course, that the foregoing relates to exemplary embodiments of the invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims.

(19) Many alterations and modifications may be made by those having ordinary skill in the art without departing from the spirit and scope of the invention. Therefore, it must be understood that the illustrated embodiments have been set forth only for the purposes of example and that it should not be taken as limiting the invention as defined by the following claims. For example, notwithstanding the fact that the elements of a claim are set forth below in a certain combination, it must be expressly understood that the invention includes other combinations of fewer, more or different elements, which are disclosed in above even when not initially claimed in such combinations.

(20) While the particular Carbon Composite Piston Crankshaft herein shown and disclosed in detail is fully capable of obtaining the objects and providing the advantages herein before stated, it is to be understood that it is merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended to the details of construction or design herein shown other than as described in the appended claims.

(21) Insubstantial changes from the claimed subject matter as viewed by a person with ordinary skill in the art, now known or later devised, are expressly contemplated as being equivalently within the scope of the claims. Therefore, obvious substitutions now or later known to one with ordinary skill in the art are defined to be within the scope of the defined elements.