Oil-pump drive for an internal-combustion engine

This invention relates to an oil-pump drive for an internal-combustion engine and a method of making an oil-pump drive for an internal combustion engine, in particular for a motorcycle.

It is known from the prior art to ensure the oil supply in an internal-combustion engine by means of gear pumps (see e.g. EP 0 451 684 A1) or internally-geared rotor pumps. It is also known to drive such oil pumps indirectly via the crankshaft using a chain or gear transmission. However, these arrangements are expensive because they require corresponding transmission members, require additional installation space, and play an important role in noise generation. Furthermore, internally-geared rotor-pump arrangements are known in which the inner rotor is pressed onto the crankshaft and is mounted in the oil-pump housing together with the outer rotor.

The present invention provides an improved motorcycle engine having a crankshaft, an oil pump coupled for rotation with the crankshaft, and a primary gear positioned between the oil pump and the crankshaft. Because the rotor of the oil pump is driven directly by a shaft via the crankshaft, additional drive components such as chains, gears and the like can be dispensed with.

In one embodiment of the present invention, a particularly simple and inexpensive connection of the oil-pump rotor to the crankshaft can be achieved if a gear arranged on the crankshaft collar has a central opening into which the shaft of the oil pump is inserted in a rotationally fixed manner. A simple positive connection between the gear and the rotor shaft can be achieved if the inserted end of the shaft and the opening in the gear are square. In alternative embodiments of the present invention, this same positive connection can be achieved by inserting a shaft having any other shape that can transmit torque into a similarly shaped opening in the primary gear.

In the first preferred embodiment of the present invention, the gear arranged on the crankshaft collar is advantageously fixed thereto by fasteners (for example bolts, screws, pins, and the like) arranged radially around the central opening, the gear simultaneously being usable as a drive for an intermediate shaft and a coupling. However, in a second preferred embodiment, the primary gear is integral with the crankshaft collar, thus eliminating the need for fasteners.

The oil pump is advantageously formed as an internally-geared rotor pump in which the inner rotor is driven by the shaft inserted into the gear of the crankshaft. Further advantageous embodiments and improvements of the oil-pump drive according to the invention for an internal-combustion engine are described below.

The present invention is further described with reference to the accompanying drawings, which show preferred 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 an scope of the present invention.

In the drawings, wherein like reference numerals indicate like parts:

FIG. 1 is a side view of the oil pump, the primary gear, and the crankshaft;

FIG. 2 is an exploded perspective view of the oil pump, the primary gear, and the crankshaft;

FIG. 3 is an exploded perspective view of the oil pump, the primary gear, and the crankshaft;

FIG. 4 is a side view of the oil pump according to a second preferred embodiment of the present invention, wherein the primary gear is integral with the crankshaft;

FIG. 5 is right side view of a motorcycle; and

FIG. 6 is a left side view of a motorcycle.

Referring first to FIGS. 5-6, the present invention relates to oil pumps for motorcycles 6 and particularly to motorcycle internal-combustion engines 8 . With reference to FIG. 1, the crankshaft 10 , formed for a V2 engine, comprises two crankshaft webs 12 and 14 , a crankshaft journal 16 on which the connecting rods connected to the two pistons are mounted, two bearing journals 18 and 20 which rotate in the main bearings of the crankcase, a front crankshaft journal 22 on which is mounted e.g. a rotor (not shown) of a dynamo, and a pinion 24 arranged between the bearing journal 18 and the front crankshaft journal 22 and acting as a drive or control means for camshafts (now shown).

The bearing journal 20 is simultaneously formed as a crankshaft collar for a primary gear 26 . In one embodiment of the present invention, as shown in FIGS. 1-3, the primary gear 26 has six through holes 28 that are arranged in a circle and through which fasteners 30 are inserted and screwed into holes 32 provided on the end of the crankshaft collar 20 . The fasteners 30 can be threaded bolts, screws, pressure fit keys, or any other fasteners known or used in the art of motorcycle construction. Similarly, in other embodiments of the present invention more or less than six fasteners 30 may be used.

With reference to FIG. 4, in a second embodiment, the primary gear 26 is formed integrally with the bearing journal 20 . In this embodiment, no fasteners 30 are necessary. Instead, the bearing journal 20 and the primary gear 26 are machined from a single piece of material. Alternatively, the primary gear 26 can be welded to the bearing journal 20 prior to the assembly of the crankshaft 10 .

In a third embodiment of the present invention, the primary gear 26 is mounted on the bearing journal 20 with a pressure fit. In this embodiment, the primary gear 26 is provided with a central opening 34 which is machined to a close tolerance. The bearing journal 20 is preferably machined to a close tolerance which is slightly larger than the central opening 34 of the primary gear 26 . The primary gear 26 is then pressed onto the crankshaft 22 at the bearing journal 20 . In still another embodiment of the present invention, a key or other similar fastener 30 may be used to help secure the primary gear 26 to the crankshaft 22 .

In the embodiment of the present invention shown in FIGS. 1-3 the primary gear 26 has a square opening 34 arranged centrally in its flange surface and into which a rotor shaft 36 of an oil pump 38 is inserted. The end of the rotor shaft 36 inserted into the square opening is also square, thus producing a positive connection between the primary gear 26 and the rotor shaft 36 . The oil pump 38 is formed as an internally-geared rotor pump in which an inner rotor 40 is connected to the rotor shaft 36 in a rotationally fixed manner. The inner rotor 40 meshes with an outer rotor 42 which has one tooth more. The rotors have different rotation axes and so the intermediate spaces change during rotation, as a result of which lubricating oil is drawn in via a suction pipe 44 and discharged under pressure via an outlet pipe 46 . The oil-pump housing 48 has fixing flanges 50 which serve to fix the oil pump 38 to the crankcase 52 , only shown schematically.

In alternative embodiments of the present invention, the bearing journal 20 and the corresponding central opening 34 in the primary gear 26 can be any shape including round, pentagonal, D-shaped, hexagonal, or any other shape that can transmit torque. This produces a positive locking connection between the rotor shaft 36 and the primary gear 26 .

The embodiments described above and illustrated in the drawings are presented by way of example only and are not intended as a limitation upon the concepts and principles of the present invention. As such, it will be appreciated by one having ordinary skill in the art that various changes in the elements and their configuration and arrangement are possible without departing from the spirit and scope of the present invention as set forth in the appended claims.

For example, while various elements and assemblies of the present invention are described as being used with a V2 engine, one having ordinary skill in the art will appreciate that the present invention can also be used with other types of V2 and V3 engines. As such, the functions of the various elements and assemblies of the present invention can be changed to a significant degree without departing from the spirit and scope of the present invention.