Rotary positive-displacement scavenging device for rotary vane pumping machine

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to rotary vane pumping machines, and more particularly, to a rotary positive-displacement scavenging device that communicates with the vane cells of the pumping machine to provide versatility in isolating, scavenging, and/or accessing the respective contents of the vane cells to enhance the performance of the rotary vane pumping machine.

2. Description of the Related Art

The overall invention relates to a large class of devices comprising all rotary vane (or sliding vane) pumps, compressors, engines, vacuum-pumps, blowers, and internal combustion engines. Herein the term pumping machine refers to a member of a set of devices including pumps, compressors, engines, vacuum-pumps, blowers, and internal combustion engines. Thus, this invention relates to a class of rotary vane pumping machines.

This class of rotary vane pumping machines includes designs having a rotor with slots with a radial component of alignment with respect to the rotor's axis of rotation, vanes which reciprocate within these slots, and a chamber contour within which the vane tips trace their path as they rotate and reciprocate within their rotor slots.

In alternate embodiments, the vanes may slide with an axial component of vane motion, or with a vector that includes both axial and radial components. The vanes may also be oriented at any angle in or orthogonal to the plane illustrated, whereby the vanes would also slide with a diagonal motion in addition to any axial or radial components. The vane motion may also have an arcuate component of motion as well. In all cases, the reciprocating vanes extend and retract synchronously with the relative rotation of the rotor and the shape of the chamber surface in such a way as to create cascading cells of compression and/or expansion, thereby providing the essential components of a pumping machine.

Some means of radially guiding the vanes is provided to ensure near-contact, or close proximity, between the vane tips and chamber surface as the rotor and vanes rotate with respect to the chamber surface. Certain radial guidance designs were described in pending U.S. patent application Ser. Nos. 08/887,304, to Mallen, filed Jul. 2, 1997, entitled “Rotary-Linear Vane Guidance in a Rotary Vane Pumping Machine” ('304 application); and 09/187,705, to Mallen, filed Nov. 4, 1998, entitled “Rotary-Linear Vane Guidance in a Rotary Vane Pumping Machine” ('705 application). The '304 and '705 applications describe a vane guidance means that overcomes a common shortcoming of the conventional means of guiding the vanes, namely that high linear speeds are encountered at the radial-guidance frictional interface. These high speeds severely limit the maximum speed of operation and thus the maximum flow per given engine size.

In the improved sliding-vane pumping geometry of the '304 and '705 applications, multiple vanes sweep in relative motion against the chamber surfaces, which incorporates a radial-guidance frictional interface operating at a reduced speed compared with the tangential speed of the vanes at the radial location of the interface. The linear translation ring interface permits higher loads at high rotor rotational speeds to be sustained by the bearing surfaces than with conventional designs. Accordingly, much higher flow rates are achieved within a given size pumping device or internal combustion engine, thereby improving the performance and usefulness of these machines.

However, even with the above advantages, efforts continue in order to further refine and enhance the performance of the rotary machine. In particular, for an internal combustion engine application, a two-stroke design achieves very high flow rates and power density yet is limited in the range over which the load may be “throttled” because of the impracticality of a vacuum-throttle system. Because the two-stroke cycle does not provide positive-displacement purging of exhaust gases and positive-displacement suction and induction of an intake charge, a conventional vacuum-throttle system cannot be effectively employed without adding external pumping devices. Although a positive-displacement ancillary pump may be added to a two-stroke vane engine for scavenging and vacuum-throttle, such a system imposes additional penalties of complexity, friction, thermal constraints, weight, size, performance limitations, and/or cost.

Whereas the pumping hardware and mechanism for the primary engine cycle (compression, combustion, and expansion) is designed to contain pressures on the order of 2000 psi, the scavenging mechanism need only handle pressures on the order of 20 psi. In addition to this two order of magnitude reduction in pressures, the scavenging mechanism need not address the many complex constraints imposed on the internal combustion pumping mechanism, such as crevice volumes, dramatic heat flux rates and associated expansion issues, surface area-to-volume ratios, critical sealing performance, and many other factors. For these reasons, it would be inefficient to employ the primary pumping mechanism for the purpose of scavenging the gases and providing a vacuum throttle. This inefficiency would manifest itself in a dramatic reduction in power density and a dramatic increase in cost, by moving to a four-stroke design to achieve scavenging and vacuum throttle. In short, the primary pumping mechanism of an internal combustion engine is an overly bulky and slow means to employ for the task of positive-displacement scavenging.

Therefore, there exists a need for a simple high-speed rotary mechanism, which, when mated to and meshed with a vane pumping machine, will provide rapid positive-displacement scavenging and vacuum throttle capability to the vane cells without imposing a significant penalty in power density, cost, or complexity.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a rotary vane pumping machine that substantially overcomes one or more of the problems due to the limitations and disadvantages of the related art.

It is an object of the present invention to provide a rotary scavenging device that meshes will the vane cells in such a way as to provide high-speed, positive-displacement scavenging (purging and induction) to the vane cells at the targeted location.

It is another object of the present invention to provide non-contact meshing of the rotary scavenging device with the vanes and rotor so that the lubrication-less design of the primary vane device may be maintained.

It is yet another object of the present invention to provide positive-displacement suction to the induction process within a two-stroke cycle so that a traditional vacuum-throttle may be employed.

In the present invention, an engine geometry is employed utilizing reciprocating vanes which extend and retract synchronously with the relative rotation of the rotor and the shape of the chamber surface in such a way as to create cascading cells of compression and/or expansion, thereby providing the essential components of a pumping machine.

More specifically, the present invention is directed to rotary vane pumping machine that includes a stator and rotor in relative rotation. The rotor has a plurality of radial vanes slots and each one of a corresponding plurality of vanes slides within a radial vane slot of the rotor. Each pair of adjacent vanes defines a vane cell. A rotary scavenging disk is disposed along the stator circumference, and is sized such that the rotary scavenging disk extends into the vane cell. An outer circumferential edge of the rotary scavenging disk is in sealing proximity with an outer circumferential edge of the rotor.

Such a rotary scavenging mechanism provides the benefits of positive-displacement scavenging and vacuum throttle capability to a two-stroke vane engine. By employing such a rotary scavenging mechanism the two-stroke vane engine reaps the benefits derived from a four-stroke design without incurring any of the associated penalties and tradeoffs. In addition, such a rotary scavenging mechanism provides additional or alternative benefits to certain applications, centering around the derived capability to access the vane cells at targeted positions during the pumping cycle, to purge the cell, exchange gases from/to the cell, and/or induct gases into the cell.

To achieve these and other advantages and in accordance with the purpose of the invention, there is provided a rotary vane pumping machine comprising a stator assembly and a rotor, with the rotor having a plurality of radial vane slots and the rotor and stator being in relative rotation. Each of a plurality of vanes extends and retracts within a corresponding one of the radial vane slots of the rotor, wherein a pair of adjacent vanes defines a vane cell. A rotary scavenging disk is disposed along a portion of the stator and extends into the vane cell, wherein an outer circumferential edge of the rotary scavenging disk is in sealing proximity with an outer circumferential edge of the rotor. The rotary scavenging disk contains at least one recess formed along the outer circumferential edge thereof. The rotation of the rotor and the rotary scavenging disk is synchronized by a gearing system.

The tip of each vane selectively contacts and slides along an inner wall of the at least one recess as the vane extends and retracts within the corresponding one of the radial vane slots of the rotor. Also, an azimuthal face of each vane selectively contacts one of the rotary scavenging disk seal projections of the rotary scavenging disk as the vane extends and retracts within the corresponding one of the radial vane slots of the rotor.

In another embodiment, a plurality of recesses may be formed along the outer circumferential edge of the rotary scavenging disk, and each recess is alternatively brought into contact with the vane as the vane extends and retracts within the corresponding one of the radial vane slots of the rotor.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, aspects, and advantages will be described with reference to the drawings, certain dimensions of which have been exaggerated and distorted to better illustrate the features of the invention, and wherein like reference numerals designate like and corresponding parts of the various drawings, and in which:

FIG. 1

is a perspective view of a rotary scavenging disk for a rotary-vane pumping machine in accordance with the present invention;

FIG. 2

is a side view of the rotary scavenging disk for a rotary-vane pumping machine in accordance with the present invention with an end plate removed;

FIG. 3

is a simplified exploded schematic end view of the gearing relationship between the rotor shaft and the rotary scavenging disk shaft for the rotary-vane pumping machine in

FIG. 1

;

FIGS. 4A through 4M

are sequential views of the rotary-vane pumping machine in

FIG. 1

as the machine progresses through a scavenging cycle, illustrating the respective positions of the rotary scavenging disk with reference to the rotor, vane and vane cells;

FIG. 5

is a side view of another embodiment of the rotary scavenging disk for the rotary-vane pumping machine in accordance with the present invention with an end plate removed; and

FIG. 6

is a simplified exploded schematic end view of a two-stroke internal combustion engine embodiment employing the rotary scavenging disk of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to an embodiment of a rotary pumping machine incorporating a rotary scavenging device, examples of which are illustrated in the accompanying drawings. The embodiments described below may be incorporated in all rotary-vane or sliding vane pumping machines.

As used herein, the term “roller” bearing or “rolling” bearing means any style of rolling, anti-friction bearing design, including for example, spherical bearings, cylindrical bearings, or any other suitably shaped rolling bearing know to those of ordinary skill in the art.

U.S. patent application Ser. Nos. 08/887,304, to Mallen, filed Jul. 2, 1997, entitled “Rotary-Linear Vane Guidance in a Rotary Vane Pumping Machine” ('304 application); 09/187,705, to Mallen, filed Nov. 4, 1998, entitled “Rotary-Linear Vane Guidance in a Rotary Vane Pumping Machine” ('705 application); and 09/258,791, to Mallen, filed Mar. 1, 1999, entitled “Vane Pumping Machine Utilizing Invar-Class Alloys for Maximizing Operating Performance and Reducing Pollution Emissions” ('791 application), are all hereby incorporated by reference in there entirety. The '304, '705 and '791 applications describe a rotary-linear vane guidance mechanism. For ease of discussion, certain portions of the '304, '705 and '791 applications will be reiterated below where appropriate.

An exemplary embodiment of the rotary engine assembly incorporating a rotary-linear vane guidance mechanism and a rotary scavenging device is shown in FIG.

1

and FIG.

2

and is designated generally as reference numeral

10

.

The engine assembly contains a rotor

100

, with the rotor

100

and rotor shaft

110

rotating about a rotor shaft axis in a counter clockwise direction as shown by arrow R in FIG.

1

. It can be appreciated that when implemented, the engine assembly could be adapted to allow the rotor

100

to rotate in a clockwise direction if desired. The rotor

100

has a rotational axis, at the axis of the rotor shaft

110

, that is fixed relative to a stator cavity

210

contained in the chamber ring assembly

200

.

The rotor

100

houses a plurality of vanes

120

in vane slots

130

, wherein each pair of adjacent vanes

120

defines a vane cell

140

. The contoured stator

210

forms the roughly circular shape of the chamber outer surface.

Each of the vanes

120

has a tip portion

122

and a base portion, with a protruding tab

126

extending from either or both axial ends near the base portion as shown in FIG.

1

. While the protruding tab

126

of the vane in

FIG. 1

is trapezoidal, the invention is not limited to such a design, it being understood that the tab may take on many shapes within the scope of the invention. The tab need not be symmetrical with respect to the vane nor with the opposing tab, if any. As shown in

FIG. 2

, the vane

120

has two azimuthal faces

120

a

and

120

b

which lead or trail the azimuthal direction of rotation of the vane when the vane is installed in the rotor

100

and the pumping machine

10

is operated. A plurality of roller bearings

131

are provided between the vane

120

and the vane slot

130

such that the azimuthal faces

120

a

and

120

b

have a rolling interface with the slots

130

of the rotor

100

.

In a rotary vane engine, momentum is transferred from the expanding gases working on the vanes

120

in the expanding vane cell

140

, to the rotor

100

through the load bearing function of the rollers in the assembly

131

. In a rotary pump and during the exhaust or pre-combustion compression cycles, momentum is transferred from the rotor to the gases in a compressing vane cell

140

through the load bearing function of the rollers in the assembly

131

. In both embodiments, the vanes

120

are radially reciprocating relative to the rotor slots

130

, and the friction of sliding between the radially reciprocating vanes and the rotor is reduced by the rolling function of the rollers in the assembly

131

. The present invention may utilize the novel vane slot roller assembly disclosed in U.S. patent application Ser. No. 09/185,707, to Mallen, filed Nov. 4, 1998, entitled “Vane Slot Roller Assembly for Rotary Vane Pumping Machine, and Method for Installing Same” ('707 application), which is hereby incorporated by reference in its entirety.

As shown in

FIG. 1

, an end plate

300

is disposed at each axial end of the chamber ring assembly

200

. Within the end plate

300

, a linear translation ring

310

spins freely around a fixed hub

320

located in the end plate

300

, with the axis

321

of the fixed hub

320

being eccentric to the axis of rotor shaft

110

as best seen in FIG.

2

. The linear translation ring

310

may spin around its hub

320

utilizing any type of bearing at the hub-ring interface including for example, a journal bearing of any suitable type and an anti-friction rolling bearing of any suitable type.

The linear translation ring

310

comprises a outer radial surface

147

having a plurality of connected linear segments

148

or facets. The protruding tabs

126

of the vanes

120

slide along a corresponding linear segment

148

of the outer radial surface

147

, which provides sufficient linear and radial guidance to the vanes

120

. A plurality of roller bearings

151

are provided between the lower surface of the vane tab

126

and the linear segment

148

, such that the vane tab

126

has a rolling interface with the translation ring

310

.

In operation, the rotor

100

rotation causes rotation of the vanes

120

and a corresponding rotation of each linear translation ring

310

. The protruding vane tabs

126

translating along the linear segments

148

of the linear translation rings

310

automatically set the linear translation rings

310

in rotation at a fixed angular velocity identical to the angular velocity of the rotor

100

. Therefore, the linear translation ring

310

does not undergo any significant angular acceleration at a given rotor rpm.

Also, the rotation of the rotor

100

in conjunction with the linear translation rings

310

automatically sets the radial position of the vanes

120

at any rotor angle, producing a single contoured path as traced by the vane tips

122

resulting in a unique stator cavity

210

shape that mimics and seals the path the vane tips trace.

No gearing is needed to maintain the proper angular position of the linear translation rings

310

because this function is automatically performed by the geometrical combination of the tabs

126

within the linear segments

148

of the linear translation rings

310

, the vanes

120

constrained to radial motion within their rotor slots

130

, the rotor

100

about its shaft

110

axis, and the translation ring hub

320

about its offset axis

321

at the center of the fixed hub

320

.

When the present invention is utilized with internal combustion engines, one or more fuel injection/induction devices

270

(

FIG. 2

) may be used and may be placed on one or both axial ends of the chamber and/or on the outer or inner circumference of the chamber. Exemplary fuel injection/induction/mixing devices are shown and described in U.S. Pat. Nos. 5,524,587; 5,524,587; and 5,836,282, which are all hereby incorporated by reference in their entirety. Each injector

270

may be placed at any position and angle chosen to facilitate equal distribution within the cell or vortices while preventing fuel from escaping into the exhaust stream. The injector(s)/inductor(s)

270

may alternatively be placed in the intake port air flow as more fully described in U.S. Pat. No. 5,524,586.

In addition, if utilized with internal combustion engines, a flame pocket (i.e., a combustion residence chamber)

260

may be provided in the chamber ring assembly

200

. The flame pocket

260

is a cavity or series of cavities within the chamber ring assembly

200

, radially and/or axially disposed from a vane cell

140

, which communicates with the air or fuel-air charge at about peak compression in the engine assembly. The flame pocket

260

may physically create an extended region in communication the vane cell

140

during peak compression.

A pair of cooling plates (not shown) may be provided, one each axially adjacent to a respective end plate

300

, to encase the engine

10

, to provide for cooling channels, and to serve as an attachment point for various devices used to operate the engine

10

. Of course, the function of the cooling plates may be incorporated in the end plates

300

. In other words, a single plate could provide the features of both the end plate

300

and the cooling plate, or separate plates could be utilized.

The cooling system for such a rotary vane pumping machine was described in U.S. patent application Ser. No. 09/185,706, to Mallen, filed Nov. 4, 1998, entitled “Cooling System for a Rotary Vane Pumping Machine” (the '706 application), which is hereby incorporated by reference in its entirety. Basically, the '706 application describes a cooling system that can cool either the rotor

100

and associated moving parts, or the stator assembly

200

, or both, depending on the operation of the rotary vane pumping machine.

The illustrated embodiment employs a two vane-stroke cycle to maximize the power-to-weight and power-to-size ratios of the machine. In other words, each vane retracts (first stroke) and extends (second stroke) once for each complete combustion or pumping cycle. By comparison, in a four vane-stroke cycle, each vane would retract and extend twice for each complete combustion or pumping cycle. The intake of the fresh air I and the scavenging of the exhaust E are provided via the scavenging device

500

as shown in FIG.

1

and FIG.

2

.

The scavenging mechanism of the present invention will now be described in greater detail. As shown in

FIG. 1

, an intake duct I and an exhaust duct E are provided in the end plates

300

, with the inner axial extent of the ducts communicating with the vane cells

140

within the chamber ring assembly

200

. Alternatively, one or both of the intake and exhaust ducts may be provided in the chamber ring assembly

200

itself. The inner axial extent (i.e., intake port) I′ of the intake duct I and the inner axial extent (i.e., exhaust port) E

1

of the exhaust duct E are best shown in FIG.

4

A. The intake port I′ and the exhaust port E′ may be located in different positions, depending on the configuration and operation of the machine. More specifically, for the two vane-stroke embodiment shown in

FIG. 2

, the intake port I′ and the exhaust port E′ are disposed in the bottom central portion of the machine

10

, given the rotation of the rotor R as depicted, and the ports are brought into selective communication with the vane cells

140

. Such selective communication is accomplished via a rotary scavenging disk

500

.

As shown in

FIG. 2

, the rotary scavenging disk

500

rotates around disk shaft

510

, the axis of which is spaced from the rotor shaft axis at a location that is preferably between the inner and outer circumferences of the chamber ring assembly

200

. The rotary scavenging disk

500

extends into the vane cell

140

, such that the outer circumferential edge

500

e

of the rotary scavenging disk

500

is in sealing proximity with an outer circumferential edge

100

e

of the rotor

100

. When in sealing proximity, the outer circumferential edge

500

e

of the rotary scavenging disk

500

separates the intake flow from the exhaust flow. The sealing proximity is accomplished via any suitable mechanism, such as a geared relationship between the rotor shaft

110

and rotary scavenging disk shaft

510

as shown in FIG.

3

. The rotary scavenging disk gear

515

rotates around disk shaft

510

, and mates with the rotor gear

115

which rotates around rotor shaft

110

. In the configuration shown in

FIG. 3

, the rotary scavenging disk

500

rotates about three times faster than the rotor. Note that the tangential velocity of the outer surface of the rotary scavenging disk need not match or even approximate the tangential velocity of the outer surface of the rotor. Of course, depending on the number of vanes, and the sizes of the rotor and rotary scavenging disk, different speed relationships and geometries can be employed. Also, the outer diameter of the rotary scavenging disk need not be round, but may have protrusions and recesses to match and seal against the shape of the rotor surface.

To accommodate each of the approaching vanes

120

as they continue to extend relative to the vane slots

130

, at least one or more recesses

520

are provided in the rotary scavenging disk

500

. The recesses

520

are shaped so as to cooperate with the azimuthal faces

120

a

,

120

b

and/or the tips

122

of the vane

120

so as to maintain a suitable sealing separation between the intake and exhaust portions, even when the outer circumferential edge

500

e

of the rotary scavenging disk

500

is momentarily not in sealing proximity with the outer circumferential edge

100

e

of the rotor

100

.

An important design goal with any scavenging approach is to minimize the fraction of hot recirculated exhaust gases, thereby maximizing scavenging efficiency. Ideally, all exhaust gases would be purged from the vane cell

140

before inducting fresh intake charge. Exhaust gas recirculation may offer pollution and other benefits, but it is best cooled before induction to preserve thermal efficiency. The rotary scavenging disk recess size, profiles and rotational speed may be optimized to minimize the exhaust recirculation. In addition, as described later, the recesses

520

not in communication with the vane cell

140

may be open to or cleared with fresh air to minimize the intrusion of exhaust gases into the recess during the exhaust phase of the scavenge process.

The continuous sealing proximity and the maintenance of the separation between the intake and exhaust area of the machine will now be described in greater detail with reference to the sequential side views of the machine

10

as shown in

FIGS. 4A

to

4

M.

Each of the views is spaced at a 5° interval, showing a full scavenge cycle of a vane cell

140

. The rotor

100

is rotating in a counter clockwise direction R while the rotary scavenging disk

500

is rotating in a clockwise direction D. As used herein, the term “approaching vane” refers to a vane that has not yet reached the bottom dead center portion of the engine cycle, where the rotary scavenging disk

500

is located, as determined by the direction of rotor rotation. The term “departing vane” refers to the same vane that has passed the bottom dead center portion of the engine cycle, where the rotary scavenging disk

500

is located, as determined by the direction of rotor rotation. Also, with regard to the vane tip portions, the terms “leading tip” and “trailing tip” are determined with reference to the direction of rotor rotation.

FIG. 4A

illustrates the vane and rotary scavenging disk orientation when the approaching vane is 30° from bottom dead center (bdc). The outer circumferential edge

500

e

of the rotary scavenging disk

500

is in sealing proximity with the outer circumferential edge

100

e

of the rotor

100

, and the recesses

520

are closed off from the vane cell

140

. With reference to the rotation R of the rotor

100

, note also that the next approaching vane

120

has not yet reached the disk area, while another departing vane

120

has already passed the disk area. In this configuration, the intake duct I′ and the exhaust duct E′ are separated from each other by the sealing proximity between the outer circumferential edge

500

e

of the rotary scavenging disk

500

and the outer circumferential edge

100

e

of the rotor

100

. As the approaching vane

120

gets closer to the disk area, the exhaust gases in the exhaust vane cell

140

e

are being compressed and forced through the exhaust duct E′. At the same time, air is being inducted into the intake vane cell

140

i

via the intake duct I′.

FIG. 4B

illustrates the vane and rotary scavenging disk orientation when the approaching vane is 25° from bottom dead center (bdc). Here, a rotary scavenging disk seal projection

532

of the recess

520

is initially exposed to the vane cell

140

e

. The outer circumferential edge

500

e

of the rotary scavenging disk

500

still maintains sealing proximity with the outer circumferential edge

100

e

of the rotor

100

to separate the intake and exhaust regions.

FIG. 4C

illustrates the vane and rotary scavenging disk orientation when the approaching vane is 20° from bottom dead center (bdc). The approaching vane

120

nearly contacts the circumferentially spaced seal projections

532

,

534

of the rotary scavenging disk

500

which define the recess

520

. In this configuration, the intake duct I′ and the exhaust duct E′ are still separated from each other by the sealing proximity between the outer circumferential edge

500

e

of the rotary scavenging disk

500

and the outer circumferential edge

100

e

of the rotor

100

. Again, as the approaching vane

120

continues to get closer to the disk area, the exhaust gases in the exhaust vane cell

140

e

are being compressed and forced through the exhaust duct E′. At the same time, air is still being inducted into the intake vane cell

140

i

via the intake duct I′. While a small amount of exhaust gas in the exhaust vane cell

140

e

may leak around the vane tip

122

and flow into the recess

520

at this point, this would not appreciably affect the performance of the machine.

FIG. 4D

illustrates the vane and rotary scavenging disk orientation when the approaching vane is 15° from bottom dead center (bdc). The approaching vane

120

now contacts the seal projections

532

,

534

of the rotary scavenging disk

500

which define the recess

520

. The forward azimuthal face

120

a

of the vane

120

contacts the rotary scavenging disk seal projection

532

while the trailing tip portion

122

b

of the vane contacts the other rotary scavenging disk seal projection

534

. In this configuration, the intake duct I′ and the exhaust duct E′ are still separated from each other by the sealing proximity between the outer circumferential edge

500

e

of the rotary scavenging disk

500

and the outer circumferential edge

100

e

of the rotor

100

, and the sealing proximity between the rotary scavenging disk seal projections

532

,

534

and the vane

120

. The exhaust gases in the exhaust vane cell

140

e

are being compressed and forced through the exhaust duct E′, and air is still being inducted into the intake vane cell

140

i

via the intake duct I′.

FIG. 4E

illustrates the vane and rotary scavenging disk orientation when the approaching vane is 10° from bottom dead center (bdc). Note that the trailing tip portion

122

b

of the vane slides in sealing proximity along the inner wall

535

of the recess

520

. The intake duct I′ and the exhaust duct E′ are still separated from each other by the sealing proximity between the outer circumferential edge

500

e

of the rotary scavenging disk

500

and the outer circumferential edge

100

e

of the rotor

100

, together with the sealing proximity between the rotary scavenging disk seal projection

532

and the vane

120

, and the trailing tip portion

122

b

and the inner wall

535

of the recess

520

.

FIG. 4F

illustrates the vane and rotary scavenging disk orientation when the approaching vane is 5° from bottom dead center (bdc). The trailing tip portion

122

b

continues to slide in sealing proximity along the inner wall

535

of the recess

520

. Although the rotary scavenging disk seal projection

532

has broken contact with the azimuthal face

120

a

of the vane

120

, the intake duct I′ and the exhaust duct E′ are still separated from each other by the sealing proximity between the rotary scavenging disk seal projection

532

and the outer circumferential edge

100

e

of the rotor

100

, together with the sealing proximity between the trailing tip portion

122

b

of the vane

120

and the inner wall

535

of the recess

520

.

FIG. 4G

illustrates the vane and rotary scavenging disk orientation when the approaching vane is at bottom dead center (bdc). In

FIG. 4G

, the entire tip portion

122

of the vane

120

is in sealing proximity with the inner wall

535

of the recess

520

. During this portion of the cycle, the outer circumferential edge

500

e

of the rotary scavenging disk

500

and the outer circumferential edge

100

e

of the rotor

100

are not in sealing proximity, but the continued sealing proximity between the vane tip

122

and the inner wall

535

of the recess

520

provides the requisite flow separation between the intake duct I′ and the exhaust duct E′. At this point, nearly all the exhaust gas in the exhaust vane cell

140

e

has been forced through the exhaust duct E′, while air is still being inducted into the intake vane cell

140

i

via the intake duct I′.

FIG. 4H

illustrates the vane and rotary scavenging disk orientation when the vane, now a departing vane, is 5° past bottom dead center (bdc). The trailing tip portion

122

b

of the vane

120

has broken contact with the inner wall

535

of the recess

520

. Now the leading tip portion

122

a

of the vane

120

slides in sealing proximity along the inner wall

535

of the recess

520

. The intake duct I′ and the exhaust duct E′ are still separated from each other by the sealing proximity between the rotary scavenging disk seal projection

534

and the outer circumferential edge

100

e

of the rotor

100

, together with the sealing proximity between the leading tip portion

122

a

of the vane

120

and the inner wall

535

of the recess

520

.

FIG. 41

illustrates the vane and rotary scavenging disk orientation when the departing vane is 10° past bottom dead center (bdc). The leading tip portion

122

a

of the vane

120

still slides in sealing proximity along the inner wall

535

of the recess

520

. The intake duct I′ and the exhaust duct E′ are still separated from each other by the sealing proximity between the outer circumferential edge

500

e

of the rotary scavenging disk

500

and the outer circumferential edge

100

e

of the rotor

100

, together with the sealing proximity between the rotary scavenging disk seal projection

534

and the rear azimuthal face

120

b

of vane

120

, and the leading tip portion

122

a

and the inner wall

535

of the recess

520

.

FIG. 4J

illustrates the vane and rotary scavenging disk orientation when the departing vane is 15° past bottom dead center (bdc). The departing vane

120

now contacts the seal projections

532

,

534

of the rotary scavenging disk

500

which define the recess

520

. The leading tip portion

122

a

of the vane

120

contacts the rotary scavenging disk seal projection

532

while the rotary scavenging disk seal projection

534

contacts the rear azimuthal face

120

b

of the vane

120

. In this configuration, the intake duct I′ and the exhaust duct F′ are still separated from each other by the sealing proximity between the outer circumferential edge

500

e

of the rotary scavenging disk

500

and the outer circumferential edge

100

e

of the rotor

100

, and the sealing proximity between the rotary scavenging disk seal projections

532

,

534

and the vane

120

.

As the rotary scavenging disk and rotor continue to rotate in their respective directions, the volume of exhaust gas in the next exhaust vane cell

140

e

starts to be compressed for eventual discharge. The exhaust gases in the exhaust vane cell

140

e

are being compressed and forced through the exhaust duct E′, and air is still being inducted into the intake vane cell

140

i

via the intake duct I′.

FIG. 4K

illustrates the vane and rotary scavenging disk orientation when the departing vane is 20° past bottom dead center (bdc). In

FIG. 4K

, the leading tip portion

122

a

of the vane

120

breaks contact with the inner wall

535

of the recess

520

and the rotary scavenging disk seal projection

532

. The vane tip

122

now contacts the stator cavity

210

. In this configuration, the intake air begins to be compressed in the vane cell

140

i

as the vane

120

sweeps along the stator cavity

210

. Again, the intake duct I′ and the exhaust duct E′ are separated from each other by the sealing proximity between the outer circumferential edge

500

e

of the rotary scavenging disk

500

and the outer circumferential edge

100

e

of the rotor

100

.

FIG. 4L

illustrates the vane and rotary scavenging disk orientation when the departing vane is 25° past bottom dead center (bdc). Here, the seal projection

534

of the recess

520

is about to lose communication with the vane cell

140

. The outer circumferential edge

500

e

of the rotary scavenging disk

500

still maintains sealing proximity with the outer circumferential edge

100

e

of the rotor

100

to separate the intake and exhaust regions.

Finally,

FIG. 4M

is similar to

FIG. 4A

, which illustrates the vane and rotary scavenging disk orientation when the departing vane is 30° past bottom dead center (bdc). The outer circumferential edge

500

e

of the rotary scavenging disk

500

is in sealing proximity with the outer circumferential edge

100

e

of the rotor

100

, and the recesses

520

are closed off from the vane cell

140

. The cycle illustrated in

FIGS. 4A through 4M

is then repeated, except that the opposing rotary scavenging disk recess

520

communicates with the approaching vane

120

.

The size of the disk, the location of the disk, and the axis of rotation of the disk, may all be varied so long as the flow separation is maintained between the intake duct I′ and the exhaust duct E′. The embodiment in

FIGS. 4A through 4M

was described with reference to a certain sized intake duct I′ and exhaust duct E′. One of ordinary skill in the art could readily understand that the size and shapes of the intake duct I′ and the exhaust duct E′ may be varied to optimize the intake and exhaust functions. By way of example, the intake duct I′ and the exhaust duct E′ may be triangular shaped, which as shown in

FIG. 4A

, would approximate the shape of the portions of the ducts that extend beyond the outer circumferential edge

500

e

of the rotary scavenging disk

500

.

Moreover, the embodiment in

FIGS. 4A through 4M

was described with regard to a rectangular shaped vane

120

having two vane sealing tip portions

122

a

,

122

b

communicating with the rotary scavenging disk

500

. It is understood that additional vane tip shapes, such as triangular or contoured, may be incorporated in the embodiments described above, perhaps with some slight modifications to the shape of the recess

520

to ensure proper sealing.

An infinite number of combinations of (a) number of recesses within the rotary scavenging disk, (b) diameter of rotary scavenging disk, (c) rotational speed of rotary scavenging disk, and (d) profile of rotary scavenging disk recesses are possible for a given application. The designer has the freedom to choose an optimum combination and persons skilled in the art of pumping machines, scavenging, and mechanical engineering could facilitate such an optimization without undue experimentation.

Also, as shown in

FIGS. 4A through 4M

, while one of the rotary scavenging disk recesses

520

communicates with the approaching vane

120

, the opposing rotary scavenging disk recess

520

communicates with an area external to the stator assembly

200

. Depending on the particular requirements of the machine designer, the opposing rotary scavenging disk recess

520

may be utilized or not. For example, if one were to enclose or encase the area external to the stator assembly

200

where the opposing rotary scavenging disk recess

520

is located, using a housing

280

for example, as shown in

FIG. 5

, the opposing rotary scavenging disk recess

520

would be cut off from the ambient air or other air supply. In such a case, no other gas is in the recess

520

as it communicates with the vane cell

140

, other than the small amount of exhaust gas that may have leaked around the vane tip portion

122

as described with reference to FIG.

4

B. Most of this exhaust gas is eventually forced out into the exhaust duct E′, although a small, insignificant portion may in turn leak into the intake vane cell

140

i.

On the other hand, if a source of fresh air were provided to the enclosure

280

, the rotary scavenging disk recess

520

communicating within the enclosure

280

would entrain a certain amount of fresh air within the recess

520

. This fresh air within the recess

520

would thus be compressed as the approaching vane

120

interacts with the rotary scavenging disk

520

as shown in the sequence of

FIGS. 4D through 4G

. As the forward vane tip portion

122

a

progresses from the orientation shown in

FIGS. 4G

, the compressed air within the recess

520

could be injected into the intake vane cell

140

i

with the proper configuration. In effect, this charge of compressed air could be manipulated to provide a supercharging effect to the normal intake air charge. While the supercharging effect in such a case would be small, on the order of 10%-15%, it could provide some enhanced performance.

Various vents

600

(see

FIG. 2

) may be supplied in and around the rotary scavenging disk

500

to vent over-pressure and/or under-pressure in the recesses

520

to other locations. The over-pressure/under-pressure conditions result from the vane tips

122

a

,

122

b

and the azimuthal faces

120

a

,

120

b

both sealing against the inner walls

535

of the recesses

520

of the rotary scavenging disk

500

as the vane

120

sweeps through the recess

520

. For example, the recesses

520

within the rotary scavenging disk

500

may be vented

600

to each other to maintain a more balanced pressure profile. In such an arrangement, the recess(es)

520

not in communication with a vane

120

may also be vented to ambient air or intake charge. Vents and scavenge ports may also be employed, positioned, and proportioned in a strategic manner to achieve a boost to the intake charge within the vane cell, thereby increasing power density.

FIG. 6

illustrates an exemplary embodiment of a two-stroke internal combustion vane engine

605

employing the rotary scavenging disk

500

as described herein. As shown, a throttle plate

610

is disposed in an intake manifold upstream of the rotary scavenging disk

500

to throttle the two-stroke engine. Note that the upstream direction is determined with reference to the flow stream arrow in the drawing. In addition, a carburetor

620

, or fuel injection/induction device

270

, may be disposed either upstream of the throttle plate

610

(solid lines in FIG.

6

), at the approximate location of the throttle plate

610

, or between the rotary scavenging disk

500

and the throttle plate

610

(phantom lines in FIG.

6

).

The rotary scavenging disk

500

need not be placed at bottom dead center or maximum vane extension, but may be offset toward the exhaust or intake side of the cycle of an internal combustion engine application. In such a manner, cycle over-expansion or under-expansion may be achieved. For example, offsetting the rotary scavenging disk toward the intake side will achieve cycle over-expansion (expansion ratio greater than compression ratio) which tends to increase efficiency for a given compression ratio, though the power density will suffer somewhat. Offsetting towards the exhaust side will achieve cycle under-expansion (expansion ratio less than compression ratio). Cycle under-expansion could be used to increase power density by increasing cell volume at intake, though the efficiency will suffer somewhat. Thus, as can be seen, the flexibility of the rotary scavenging disk placement allows the engine designer to optimize the performance of the engine for a specific application.

It will be apparent to those skilled in the art that various modifications and variations can be made in the system and method of the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Number	Name	Date
1743539	Gasal	Jan 1930
3437079	Odawara	Apr 1969
3548790	Pitts	Dec 1970
3923431	Abbey	Dec 1975
4432203	Fischer	Feb 1984
5372107	Smythe	Dec 1994

Number	Date	Country
1551150	Mar 1970	DE
356098527A	Aug 1981	JP
408246888A	Sep 1996	JP

Rotary positive-displacement scavenging device for rotary vane pumping machine

Information

Patent Number

Date Filed

Date Issued

Inventors

Original Assignees

Examiners

Agents

CPC

US Classifications

Field of Search

US

International Classifications

Abstract

Description

Claims

US Referenced Citations (6)

Foreign Referenced Citations (3)