Oil pump

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an oil pump for an internal combustion engine. More particularly it relates to an improved gerotor gear oil pump for use with a motorcycle engine employing a dry sump lubrication system and providing an improved design and ratio of scavenging pump capacity to engine supply side capacity. The design provides both improved performance and lubrication for the motorcycle engine and a gain in net horsepower in such an engine despite the use of increased gear size which would normally cause a decrease in net horsepower of the engine. Additionally, the modular design of the preferred embodiment provides the ability to assemble an oil pump with two or more pumping chambers into a single pump unit that is customizable to the required performance characteristics of the motorcycle for the type of riding intended.

In a preferred embodiment, the device features a multiple piece formed pump unit having a pressure pump housing and a scavenge pump housing separated by a separator plate and which are configured for cooperative sealed engagement in line and adjacent to each other to thereby house the rotating gerotor gears housed internally in each separate housing making up the pump housing. An outer wear plate, or sidewall formed by the engine to which the pump unit attaches defines the outer wall of a pressure chamber formed by the pump housing and the separator plate. The device also features the gears of the scavenge pump portion sized to specific pumping volume ratios in relation to the gears in the pressure pump portion to scavenge oil and gas pressure from the engine at a ratio sufficient to minimize windage and drag caused by oil occupying one or a plurality of sumps in the engine by draining such oil to a fluid reservoir supplying the pressure pump before it encumbers the rotation of internal engine components. Concurrently the scavenge pump portion, when in a correct ratio to the pressure pump fluid pumping capacity, ensures that the pressure pump is provided with a constant and uninterrupted supply of lubrication fluid from the fluid reservoir which can be delivered to engine components by the pressure pump during all phases of engine operation from idle to high RPM long duration operation.

The multi-piece design also allows the pump to be manufactured and sold as a kit which features cooperating pump gears and scavenge gears and pump housings and scavenge housings that are sized at different ratios in relation to each other. In this fashion the ratio of fluid volume pumped from the sumps by the scavenge pump in relation to the oil pumped by the pressure pump portion may be adjusted by using different sized gears and different sized engageable housing components. The chosen gears and housings form the two separate pumps which may then be assembled into a custom oil pump with the separator plate and the end plate or an engine wall as the case may be, with the desired ratio of scavenge pump volume to pressure pump volume to fit the intended use of the motorcycle.

2. Prior Art

Motorcycle engines in prior art generally employ a lubrication system that uses either a dry sump or wet sump. In both such wet sump and dry sump lubrication systems, the lubrication fluid, most commonly motor oil, collects in a sump at the bottom of the crankcase after the oil has been pumped to and lubricated various components of the engine. In a wet sump lubrication system, using a single oil pump, the oil is generally pumped directly from the crankcase sump or other sumps formed in the engine case, to the components of the engine requiring lubrication. In a dry sump lubrication system, the oil that collects in the engine sump, is pumped out of the crankcase sump by a first pump, which delivers the oil to a reservoir. Oil stored in the reservoir is then communicated via conduits to a second or pressure pump which pumps it to the parts of the engine requiring oil during operation through communicating conduits.

Gerotor oil pumps are well known in the art for pumping fluids and available from many sources such as Nichols Portland of Portland, Me. and Federal Mogul of Detroit, Mich. The theoretical flow ripple of the fluid pumped by gerotor pumps depends on the number of teeth in the pump gears and the specific geometry of the gerotor but in general more teeth means a lower flow ripple. Additionally, an inner gerotor gear with an even number of teeth typically has a lower fluid flow ripple than an inner gear having an odd number of teeth.

Since hydraulic power is a function of flow and pressure, the mechanical energy losses to the driving engine generally are caused by the viscous drag on the gears being driven. Consequently the gerotor with the smallest outside diameter will generally cause the lowest power loss to an engine driving it due to the developed viscous drag. Additionally smaller gears minimize vibration. Increasing gear size would generally be expected to cause a concurrent decrease in the net available horsepower of the engine driving the pump, since viscous drag is increased from the increased pumping and more horsepower is then required to power the pump. As such, engine manufacturers generally minimize the size of the gears to minimize vibration and power loss from the engine required to power them.

U.S. Pat. No. 6,047,667 (Leppanen) discloses an oil lubrication system using a gerotor pump for use in a motorcycle engine. However, Leppanen teaches the use of a one piece casing housing two adjacent pump gears and fails to teach any benefits derived from the critical ratio of the scavenging gear and resulting pumping volume to the pressure gear and resulting pressure pumping volume. Neither does Leppanen provide any ability to assemble pumps and adjust ratios of the scavenge and pressure section by the use of different components from a kit of different sized scavenge and pressure gears and casings all of which may easily be assembled into a functioning pump with optimum dimensions and ratios.

U.S. Pat. No. 6,116,205 (Troxler) also teaches the use of a gerotor oil pump for a motorcycle engine to drain two different sumps. The use of such a pump to simultaneously drain two different sumps on an engine, and pressurize oil passages on that engine is well known art in lubrication systems for internal combustion engines including motorcycles and automobiles. Troxler teaches the use of a one piece pump housing which is not designed to allow gear ratio adjustments and fails to teach any benefit from such adjustments or increasing the volume pumping size of the pumps. Neither does Troxler make any accommodation to the gear mounting on the drive shaft to allow for wear or end play which might cause the gears to bind with the body or endwalls when the pump is assembled.

As such, there is a pressing need for an oil pump with separate housings and separate scavenging and pressurizing chambers therein which may be specifically sized such that the ratio of the scavenging gears to the pressurizing gears is optimized to vent fluids from the engine sumps at an optimum rate during all operation speeds. Such a device should allow for maximum lubrication by the oil pressurizing pump at all engine speeds and optimize removal of oil and internal gas pressure from the sumps to minimize windage and interference by fluids in the sumps with the rotating mechanical components of the engine.

Still further, such a device when assembled from a plurality of different pump components into a single pump unit would offer the further benefit of the ability to choose specific gearing matched to specific assembleable housings or casings to form the two-chambered pump. By the careful selection of the fluid pumping volume of the scavenge portion of the formed pump to the pumping volume of the pressurizing portion, from a plurality of configurable casings and gears designed to interface and assemble to a pump, manufacturers, distributors, and users, can assemble a properly sized and proportioned pump with the optimum ratio of volume of the scavenging pump to the pressurizing pump to maximize both lubrication and net horsepower to each individual engine and the expected operating parameters of that engine. Additionally, by providing a means to accommodate end play and/or an out of tolerance mounting of the gears on the drive shaft, such a system would eliminate potential binding of the gears on the pump casings when the pumps are assembled and used.

SUMMARY OF THE INVENTION

Applicant's device is an improved two chambered gerotor oil pump for use on internal combustion engines. The preferred embodiments of the device, for use on a dry sump style engine, feature a scavenging pump chamber formed in a scavenging housing and further defined by a sidewall opposite a separator plate, and, an inline pressure pump chamber formed in a pressure housing and further defined by a separator plate between it and the scavenging pump and an opposing end wall. Gerotor gears operatively occupy both the scavenging pump chamber and the pressure pump chamber and are both situated for inline mounting on a driving shaft communicating axially through the center portion of both chambers. In some instances the sidewall of the scavenging chamber or exterior wall of the pressure chamber may be provided by mounting the assembled pump housings to the engine block or factory end plates or both the sidewall and the exterior wall may be provided as parts for use in with the assembled pump assembly to maintain tolerances between the parts.

In use in the current best embodiment the improved oil pump would be assembled from the various components to yield a pump for both scavenging lubricating fluids from one or a plurality of engine sumps and pumping such lubricating fluids for the engine used in combination herewith which has the best ratio of gear sizing to yield the pumping volume for the intended engine and the use of the intended engine. For example motorcycles for competition tend to reach high engine speeds and to constantly accelerate and decelerate such engine speeds. Conversely, street and highway driven motorcycles tend to accelerate less and to shift to higher gears for long periods of riding at highway speeds with constant but lower RPM than those encountered by racing motorcycles.

It is an object of this invention to provide an oil pump for internal combustion engines, especially motorcycles, which ratios the pumping volume of the scavenge pump to the pumping volume of the pressure pump, to maximize performance and minimize power loss.

Another objective of this invention is to provide such a multi chambered oil pump which is assembled from modular components allowing for the adjustment of gear sizes in each respective pump section to achieve the best size and ratio of pumping volume therebetween for the intended installation of the pump.

An additional objective of this invention is to provide a multi chambered oil pump which is assembled from modular components allowing for the easy replacement and repair of the assembled pump components.

A still further object of this invention is the provision of an oil pump with a scavenging pump to pressure pump pumping volume ratio which minimizes or eliminates horsepower loss to the driving engine by removing excess liquid and gas from the engine sumps which interfere with mechanical movement, while providing an adequate supply of lubrication fluid to a reservoir and communicating pressure pump for engine lubrication purposes.

Further objectives of this invention will be brought out in the following part of the specification, wherein detailed description is for the purpose of fully disclosing the invention without placing limitations thereon.

BRIEF DESCRIPTION OF DRAWING FIGURES

FIG. 1

is a perspective view of the disclosed device depicting the components of the multi chambered oil pump and their attachment to a motorcycle engine used in combination herewith.

FIG. 2

is a front-view of the internal gerotor gears of the scavenging pump.

FIG. 3

is a side cut away view of the multi chambered modular oil pump showing the diameter ratios of the gears of the two separate pumps and inline relationship with the shaft.

FIG. 4

depicts scavenge pump inner gerotor gear having a counter bore formed on the aperture for accommodating shaft play and manufacturing tolerances when mounting the gear a relief formed on the driving shaft.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE DISCLOSED DEVICE

Referring now to the drawings

FIGS. 1-4

disclose the preferred embodiments of the herein disclosed device

10

which is a multi chambered oil pump for operative attachment to, and use in combination with, an internal combustion engine

11

such as a motorcycle.

In a first preferred embodiment as shown in

FIG. 1

the device

10

features a pair of gerotor pumps to form the device

10

which has a scavenging pump

12

mounted in line with a pressure pump

14

. As shown, a pump porting plate

16

provides a means to interface the device

10

with an engine

11

and the oil conduits of the engine and port the lubricating fluid such as oil from one or a plurality of engine sumps (not shown) to one or a plurality of scavenging intake ports, in this case a first savaging intake port

18

and a second scavenging intake port

20

through which oil is drawn into the scavenging pump

12

by negative pressure generated by the scavenging pump

12

at the two intake ports. The two intake ports

18

and

20

, would communicate fluid into the scavenging pump

12

and through a sidewall. This sidewall might also be formed by the engine casing with one or a plurality of intake ports providing fluid to the scavenging pump

12

but the current best mode provides the porting plate

16

for attachment to the engine

11

for such an interface.

The scavenging pump

12

receives oil from the intake ports

18

and

20

and therein discharges the pressurized oil through the scavenging discharge port

22

in the porting plate

16

which communicates the pressurized oil through an internal conduit to a porting plate discharge conduit

24

. This is the conventional manner of gerotor pumps which receive oil through an elongated or curved apertures a sidewall moving it to a similarly shaped aperture forming the discharge port also in a sidewall. The porting discharge conduit

24

communicates oil from the scavenging pump to an oil reservoir (not shown) for storage and communication to the pressure pump

14

.

The favored configuration shown in

FIG. 1

is best suited for use with motorcycles using a dry sump system which communicate oil from one or a plurality of engine sumps to a scavenging pump

12

which is in fluid communication with an oil reservoir (not shown). The oil reservoir in turn is in fluid communication with the pressure intake port

32

of the pressure pump

14

which commentates through a pressure sidewall or endplate

34

to the pressure pump

14

. The rotating gears receive the oil between them from the intake port

32

and rotate toward the discharge port

36

thereby discharging the oil to the engine through the pressure discharge port

36

which is in sealed communication with an engine oiling system intake conduit and which distributes the pressurized oil to various engine parts needing it. The discharge port is operatively located to communicate through the endplate

34

to receive oil from the pressure pump

14

. The discharge port might also be placed in the engine block to mate with the side of the pressure pump

14

however the current best mode is anticipated for use with a properly channeled endplate

34

which sandwiches the assembled device

10

between the endplate

34

and the motor cycle engine

11

and with the gears mounted upon the driving shaft

46

which in the illustrated embodiment has a relief

47

extending from a shoulder

49

formed at a distal end of the driving shaft

46

to accommodate the gear mounting thereon.

Further shown in

FIG. 1

is the current best mode of the device

10

which employs a plurality of gerotor style pumps depicted as scavenge pump

12

and pressure pump

14

. Gerotor pumps typically employ two rotating rotors or gears. As best shown in

FIG. 2

, an outer gear, which as depicted is the scavenge outer gear

40

has a smooth circumference

41

designed to rotate inside an operatively dimensioned circular chamber, which as shown as circular cavity

38

. The outer gear

40

has a geared interior chamber

43

. An inner gear which in this case is shown as inner scavenge gear

42

, having one less tooth than the outer gear, rotates inside the outer gear when turned by the driving shaft

46

. Since the outer gear

40

has a centerline at a fixed eccentricity from the centerline of the inner gear

42

, and one more tooth than the inner gear, both the outer gear and inner gear will rotate when powered by the driving shaft

46

. The inner chamber

43

draws in fluid communicated thereto through one or a plurality of intake ports formed in a side wall and best depicted in

FIG. 1

as the first scavenge intake port

18

and second scavenge intake port

20

however the number of intake ports will depend on the number of engine sumps being scavenged by the pump. As both gears rotate on the driving shaft

46

the empty space in inner chamber

43

where the gears do not engage decreases in size as it rotates from communication with the intake ports

18

and

20

to communication with the scavenge discharge port

22

thereby forcing fluid out into the scavenge discharge port

22

which is in fluid communication with the engine reservoir. The pressure pump

14

works in essentially the same manner.

As shown in

FIG. 1

, in the current best mode, the scavenging discharge port

24

communicates pressurized oil through the scavenge discharge passage

26

which communicates through the scavenge housing

28

, the divider plate

29

, and the pressure housing

30

when the components are in assembled in line and in operative sealed engagement. The scavenge discharge passage

26

is in sealed fluid communication with an internal engine reservoir. Fluid conduits from the engine reservoir therein communicate oil to the pressure intake port

32

and thus supplies oil scavenged from the sumps by the scavenging pump

12

to the pressure pump

14

.

The pressure pump

14

pressurizes the oil further wherein it is discharged from the pressure pump

14

through the pressure discharge port

36

which is in sealed communication with the appropriate intake port on the engine requiring pressurized fluid to lubricate and operate the engine during operation. Pressurized fluid from the pressure discharge port

36

may also be sent through a filter means and may be regulated for proper pressure during its return to the appropriate port in the engine

11

by a means to regulate fluid pressure.

As noted, the device

10

is modular in construction with separate scavenging pump

12

and pressure pump

14

sections which assemble in line to mount upon the driving shaft

46

. As shown in

FIG. 2

the scavenging pump section features a scavenge housing

28

with a circular cavity

38

formed therein sized to accommodate the outer scavenge gear

40

and the inner scavenge gear

42

. A notched aperture

44

is dimensioned for cooperative operative engagement over a driving shaft

46

which is powered by the engine

11

during operation and provides the rotational power to operate the scavenging pump

12

during operation of the engine

11

. In the current best mode, a counter bore

45

is formed on both sides of the notched apertures

44

of both the inner scavenge gear

42

. This counter bore

45

provides a means to accommodate lateral translation of the driving shaft

46

also known as end play, as well as a means to accommodate the tolerances of manufacturing which could cause the gear to bind when mounted, and still allow the device

10

to be assembled in line from two different pump sections. This counter bore

45

thereby allows for some end play of the driving shaft

46

during operation and the easy assembly of the gears inline on the driving shaft

46

without binding after assembly even if the tolerances of the engine components have increased due to wear or other reasons.

The pressure pump

12

is also of modular construction featuring a pressure housing

30

having a circular aperture

48

dimensioned for operative engagement of the rotating outer pressure gear

50

therein which is driven by the inner pressure gear

52

which also has a center aperture dimensioned for cooperative engagement over the driving shaft

46

when the device is assembled and cooperatively engaged over the driving shaft

46

.

As shown in

FIG. 3

, the device

10

is of modular construction connected by bolts (unnumbered) so as to be readily disassembled provides the ability to be assembled from different components of differing sizes yielding different fluid pumping volumes depending on the engine to which they are attached. When the device

10

was assembled in the current best mode, and engaged with a HARLEY DAVIDSON® Twin Cam 88 engine, experiments with the ratios of the fluid pumping volume of the scavenging gears

40

and

42

to the fluid pumping volume of the pressure gears

50

and

52

showed an unexpected result. When larger than original gears were used for both the pressure pump

14

and the scavenging pump

12

, instead of losing horsepower as would be expected from the larger gears requiring more force to rotate, the engine actually showed an increase in net horsepower. This unexpected result once achieved was improved on by carefully adjusting gears with a substantially equal diameter “D” and with a determined ratio of the width “A” of gears of the scavenging pump

12

to the width “B” of the gears of the pressure pump

14

to yield the optimum fluid pumping volume of the scavenging pump

12

to the pressure pump

14

. In the current best mode as used in combination with a HARLEY DAVIDSON® Twin Cam 88 the device

10

is operatively mounted, sandwiched between a factory supplied endplate and the engine

11

. The endplate on this model of HARLEY DAVIDSON provides conduits to communicate oil from the scavenging pump

12

to the reservoir and from the reservoir to the pressure pump

14

and then from the pressure pump

14

back to the engine

11

. In this application, a gear diameter “D” in a range of 1.8 inches to 2.25 inches works best with the current best embodiment for this engine being substantially 2 inches. On the same engine it was found that assembling the respective gears with a ratio of with “A” to width “B” with a ratio between 1.9 to 1 and 2.5 to 1 with the current best ratio of “A” to “B” being substantially 2.42 to 1. The higher fluid pumping volume of the scavenging pump

12

to the pressure pump

14

provides not only insures an adequate supply of oil to the reservoir to feed the pressure pump

14

at all engine speeds, the scavenging pump

12

uses a portion of the extra volume pumping capability to pull gas from the engine sumps and interior thereby reducing internal engine pressures as well as windage from oil in the sumps. The exact ratio of volume pumping chosen would depend on the intended type of application or use of the engine however the aforementioned ratios work exceptionally well with the HARLEY DAVIDSON® Twin Cam 88 engine when the device

10

is assembled from both pumps

12

and

14

, and sandwich mounted between the factory endplate and the engine

11

. The device

10

in this pumping volume ratio configuration would also work well in similar motorcycle engines and the addition of the counter bore

45

alleviated gear binding in the scavenge pump

12

against the side wall or divider plate

29

from out of tolerance engine specifications or wear.

By assembling the device

10

using modular components to form both the scavenging pump

12

and the pressure pump

14

which assemble in line for mounting on the driving shaft

46

, it is easy to adjust the ratio of the fluid pumping volume of the scavenging pump

12

in relation to the fluid pumping volume of the pressure pump

14

. This is done by simply substituting pressure housings

28

with larger or smaller widths “B” for assembly into a complete device

10

along with scavenging housings

28

having different widths “A.” The appropriately sized gears generally of equal diameter, would occupy the circular cavity

38

of the pressure housing

30

and the circular aperture

38

of the scavenge housing

28

respectively. Thus, when a user wishes to change the ratio of fluid pumping volume of the scavenging pump

12

to that of the pressure pump

14

, they can simply assemble the device

10

from a kit of components containing a plurality of different widths “A” and “B” to yield the ratio desired to appropriately scavenge fluid and gas pressure from the engine sumps to minimize fluid interference with mechanical action yet provide optimum pressure and volume for engine lubrication and operation. As is obvious to those skilled in the art, the gears of the respective pumps need not be the same diameter “D” and it would also be possible to adjust the respective fluid pumping volumes of the two pumps by changing one of the pumps to a larger diameter gear and casing. However using equal diameter “D” works best in the current preferred embodiments since it allows for easy assembly of the components inline.

While all of the fundamental characteristics and features of the multi chambered oil pump have been described herein, with reference to particular embodiments thereof, a latitude of modification, various changes and substitutions are intended in the foregoing disclosure and it will be apparent that in some instances, some features of the invention will be employed without a corresponding use of other features without departing from the scope of the invention as set forth. It should be understood that such substitutions, modifications, and variations may be made by those skilled in the art without departing from the spirit or scope of the invention. Consequently, all such modifications and variations are included within the scope of the invention as defined herein.