US3817666A

US3817666A - Rotary positive displacement unit

Info

Publication number: US3817666A
Application number: US00331781A
Authority: US
Inventors: E Wildhaber
Original assignee: Individual
Current assignee: Individual
Priority date: 1973-02-12
Filing date: 1973-02-12
Publication date: 1974-06-18
Anticipated expiration: 1991-06-18

Abstract

The units contain pairs of toothed intermeshing members running on axes that intersect at an angle differing from 180* by half the tooth-height angle. Their tooth numbers differ by one. Ducts lead fluid to and from the intermeshing members. In units containing two of said pairs their larger members are coaxial and form a rigid rotor. The invention gears this rotor directly to the outside, without driving through the smaller member of one pair. It thereby minimizes the load transmitted through the tooth sides of each pair. The shaft geared to said rotor is positioned to minimize the bearing loads thereof. Generally the shaft axis lies in an axial plane of said rotor inclined to the plane of the axes of each of said pairs. The improvement further resides in the mounting of the smaller member of a pair and in the shape of the duct openings at the intermeshing members.

Description

United States Patent [191 Wildhaber June 18, 1974 [57] ABSTRACT The units contain pairs of toothed intermeshing members running on axes that intersect at an angle differing from 180 by half the tooth-height angle. Their tooth numbers difier by one. Ducts lead fluid to and from the intermeshing members. In units containing two of said pairs their larger members are coaxial and form a rigid rotor. The invention gears this rotor directly to the outside, without driving through the smaller member of one pair. 1t thereby minimizes the load transmitted through the tooth sides of each pair.

The shaft geared to said rotor is positioned to minimize the bearing loads thereof. Generally the shaft axis lies in an axial plane of said rotor inclined to the plane of the axes of each. of said pairs. The improvement further resides in the mounting of the smaller member of a pair and in the shape of the duct openings at the intermeshing members.

9 Claims, 8 Drawing Figures ROTARY POSITIVE DISPLACEMENT UNIT [76] Inventor: Ernest Wildhaber, 124 Summit Dr.,

Brighton, NY. 14620 [22] Filed: Feb. 12, 1973 [21] Appl. No.: 331,781

[52] US. Cl 418/195, 418/200, 60/396] [51] Int. Cl. FOlc l/08, F03c 3/00, F04c 17/04 [58] Field of Search 418/9, 10, 194, 195, 199, 418/200; 60/3945, 39.61, 39.63 [56] References Cited UNITED STATES PATENTS 739,207 9/1903 Nielsen 418/195 1,912,634 6/1933 Gray 418/193 3,207,137 9/1965 Lanahan 418/195 3,236,186 2/1966 Wildhaber 418/193 3,273,341 9/1966 Wildhaber 60/3961 3,433,167 3/1969 Craig 418/195 3,442,181 5/1969 Olderaan 91/500 3,492,974 2/1970 Kreimeyer 418/68 Primary Examiner-Carlton R. Croyle Assistant Examiner-John .1. V rablik v 76 9! 9o: as if PATENTEMuu-r a an aianlsse SHEEI 30$] 3 ROTARY POSITIVE DISPLACEMENT UNIT This is an improvement on my US. Pat. Nos. 3,236,186 and 3,273,341 granted in 1966. The invention can be embodied as a compressor for air or gases, as an engine for compressed air, steam, or hot combustion gases, as a pump or motor for liquids, and particularly as a rotary positive displacement unit containing two pairs of intermeshing toothed members. The two pairs may be used in parallel or in series, as for instance one pair compressing air and the other letting it expand after or during combustion, to provide an engine.

For the last-named case a unit has been proposed wherein the engine power is transmitted to the outside through the smaller member of its pair. This results in an ample amount of torque transmitted through the tooth sides of the engine pair.

One object of the present invention is to drastically reduce this torque. A further object is to then do away with liquid lubrication of the tooth surfaces or to much reduce it.

A further aim is to provide a unit with two pairs of rotary members wherein the gear drive is placed to produce minimum bearing loads. A further object is an improved mounting of the smaller member of the pair. A still other aim is to reduce leakage by improving the shape and position of the fluid ducts where they reach the intermeshing pair of members.

Other objects will appear in the course of the specification and in the recital of the appended claims.

The invention will be described with reference to the drawings in which FIG. 1 is a side view of a pair of toothed intermeshing members used in the invention, the view being taken at right angles to the plane of their intersecting axes.

FIG. 2 is a development into a plane of what might be called the back cone of the smaller member, illustrating the contact of its tooth ends. It represents the intersection with the extended teeth, of a cone coaxial with said member and tangent to the spherical outside surface.

FIG. 3 is a fragmentary view of the intermeshing teeth, taken radially along the line of contact of the conical pitch surfaces.

FIG. 4 is a radial view along the plane of the axes taken at the diametrically opposite side of the intermeshing members.

F IG. 5 is an axial section of a compressor showing the improved mounting of the smaller member.

FIG. 6 is an axial section of a unit containing two pairs of intermeshing members. It applies for instance to a pair of compressors.

FIG. 7 is a diagram showing the position of the gears with respect to the plane of the axes of the pairs.

FIG. 8 is an axial section of a unit containing a compressor pair and an engine pair of members, constructed according to the invention.

FIG. 8a is a repetition of FIG. 8, showing added to it a combustion chamber 98 and

passages

96, 99 to and from it.

The intermeshing rotary members 11, 12 (FIG. 1) turn on axes 11', 12' that intersect at 0. They have tooth numbers differing by one. The smaller member 12 may have n teeth and the larger member 11 may have (n l) teeth. The teeth are tapered. They extend between a conical face surface and a conical root surface having a common apex at 0, best seen in axial section FIG. 5. The angle 14 between the axes 11, 12' differs from degrees by half the angular height 15 of the

teeth

16, 17, so that the teeth may remain in contact with one another along the entire circumference of the members. The tooth shape has been described at length in the aforesaid patents.

In one procedure the outside end-surface 18 of the teeth 17 of the smaller member 12 is assumed, for instance as a conical surface with apex at 0. The entire tooth surface of the larger member is then formed conjugate to said end surface 18, so that end-surface 18 completely envelops it when member 12 turns in engagement with member 11 at the ratio n l/n of the tooth numbers at the angular setting of the final pair. This results in a path of contact 20 between the tooth tops 18 and the teeth 16. It is shown in dotted lines in FIGS. 1 to 3.

The complete tooth shape of the smaller member 12 is formed conjugate to the just defined tooth shape of the larger member 11. This results in a further path of contact 21, 21' between the tooth sides, (FIG. 3). The mating tooth sides have little relative curvature. They hug each other, so that the surface stresses at the contact remain low.

While gears with parallel axes, an external gear and an internal gear with one more tooth, are restricted to a tooth depth of one module, that is to the circular pitch divided by 11', (11 3.1416), such restriction does not apply to the design with intersecting axes. A tooth depth or tooth height of 2 /2 module or more may be provided. This avoids the excessive inclination of the tooth sides of parallelaxes gears and provides a sufficient duration of contact between the tooth sides themselves, along path 21 and 21'.

This is clearly shown in FIG. 3.

Seals are formed by tangential contact at the contact points of the tooth tops 18. These seals extend all around the periphery of the members. Further seals are formed at the contact points, such as 23, 23' (FIG. 3), of the paths of contact 21, 21' between the tooth sides. These latter seals are however confined to the region of deepest penetration of the members, where they have little effect.

The teeth of the two members leave spaces between them. Space 25, FIG. 4, has the maximum volume. It is sealed at 24, 24'. The volumes diminish around the periphery of the pair. Thus volume 26, (FIGS. 1, 2), sealed at 26 26', is slightly smaller. And

volumes

27, 28, 29 are progressively smaller until they almost disappear in the region of deepest penetration, (FIG. 3). Their seals are respectively at 26', 27; 27', 28; 28, 29.

In a compressor, when

members

11, 12 rotate in the direction of

arrows

30, 31, air or fluid filling space 25 is progressively transformed to

volumes

26, 27, 28, where it may get within reach of the outlet opening. Air or fluid is admitted while the penetration of the two members decreases, between the positions shown in FIGS. 3 and 4.

In an engine or motor fluid under pressure is admitted to spaces 29 and possibly 28, when members 1 1, l2 rotate in directions opposite to

arrows

30, 31. It expands as it reaches

volume

27, 26, 25, and leaves the intermeshing members during their increasing penetration, which lasts through about half a turn.

When the unit is embodied as a pump for liquids, the exhaust ducts start and the intake ducts end near the location shown in FIG. 4.

In FIG. 1 dotted lines indicate the shape of the compressor outlet duct 32, as it leaves the sphericaloutside surface of the

pair

11, 12. To avoid or restrict leakage as the members turn, one side 32 of the duct opening approximately follows the path of contact 20 of the tooth tops 18 for a stretch adjacent the end furthest away from the plane of the axes ll, 12. Considerable departure is permitted without materially affecting the action, while keeping at a distance from the root surface of the smaller member. The other side 32 follows the root surface of the larger member 11. The duct opening widens as it approaches the plane of the axes 11', 12'.

An intake duct opening of larger length is provided on the opposite side of said plane.

In an engine or motor using compressible fluid, duct 32 is the inlet and the longer duct opening on the opposite side the exhaust, provided that the members rotate in directions opposite to

arrows

30, 31.

The longer opening, the intake on a compressor, is less critical. One end of this opening 34 is indicated in dotted lines in FIG. 4.

The ends of both openings adjacent pitch point 35, FIG. 3, are separated a moderate distance, (not shown).

It will now be demonstrated that the fluid pressure exerts practically no turning moment on the smaller member. Fluid in compartment 26, (FIGS. 1 and 2), exerts a pressure whose resultant force is perpendicular to the straight connecting line of the sealing points 26 26', and perpendicular to the plane through apex 0 of which this line is a part. It acts midway between the seals and is the product of the area in said plane and the pressure per unit area.

Inasmuch as line 26 -26 extends almost peripherally, the resultant force has a very small distance from the turning axis 12 and exerts only a small turning moment on member 12. It is opposed to the direction 31 of its rotation.

The forces resulting from fluid pressure in

compartments

27, 28, 29 are perpendicular respectively to the connecting lines 2627, 2728, 28-29 and are determined as described for compartment 26. The forces of

compartments

27, 28 almost intersect the axis 12 and thus exert very little turning moment.

The resultant force of compartment 29 bypasses the axis 12' on the opposite side as compared with the one of compartment 26, and exerts a turning moment in the direction of rotation. Because of the larger pressure in compartment 29, it more than balances the opposite turning moment. It may just about overcome the frictional resistance, so that member 12 floats freely about its axis.

By not driving through the smaller member, the tooth loads of the members are minimized. The inventiontakes advantage of this particularly in units containing two pairs of members.

FIG. illustrates an improvement in the mounting of the smaller member, whose axis 12 intersects axis 11 of member 1 1 at 0. Member 12 of compressor 40 is rotatably mounted on a spherical projection 41 rigid with member 11 and further in a region spaced therefrom. The further away from 0 this region is, the larger is the load carried by projection 41. Because of its considerable slant and its moderate load-carrying area it is desirable to keep its load down. The invention does this, using an external portion 42 rigid with the housing 43 and projecting towards said intersection point 0 to the inside of the smaller member 12. Projection 42 carries an antifriction bearing 44 capable of carrying combined radial and axial load.

If desired, sliding bearings may be used instead, as at 45, 46 in FIGS. 6 and 8. Their projecting portion is preferably tapered, decreasing in diameter towards 0.

The

bearings

44, 45, 46 are preferably designed to carry nearly the total bearing load needed to rotatably mount the smaller member. If needed, the direction of the bearing load can be influenced by exposing more of the spherical outside surface of the member to the compressed fluid.

The larger member 11 is secured to a flange 19 of the part that also contains the spherical projection 41 and a shaft portion. It may be secured in any suitable known way, for instance by bonding.

FIG. 6 shows a twin compressor constructed accord ing to the invention. It is made up of two

identical compressors

50, 50" to double the output. They contain intermeshing members 51', 52' and 51", 52 respectively. The members are shaped like the described

members

11, 12.

The

larger members

51, 51" are coaxial and rigidly connected with each other by shaft portions 53', 53" and a toothed face coupling 54. Rigid engagement is maintained by a bolt 55 and nut 56, to form a rigid rotor. A cylindrical pinion 57 is secured to one of said shaft portions.

Bearings

58, 59 mount this rotor assembly.

The axes of all rotating members 51', 52; 51", 52" lie in a common plane. Pinion 57 meshes with a gear 57'. Its axis 60 is parallel to the rotor axis 61 and thus lies in an axial plane of the rotor. This plane includes an angle with said common plane, the drawing plane of FIG. 6. In accordance with the invention this angle is so determined as to minimize the loads on

bearings

58, 59.

Diagram FIG. 7 is a view taken along the axis 61 of said rotor. Circle 62 represents the outline of its members 51', 51". The drawing plane coincides with their mid-plane 63. The said common plane 64 of the axes appears vertical in FIG. 7.

With rotation in direction of arrow 65 the fluid pres sure creates a force 66, on a compressor. This vector is inclined to the mid-plane and intersects it at 67. The forces exerted on the two members 51', 51" are symmetrical to the mid-plane, like the members themselves. Their thrust components along axis 61 are equal and opposite. They balance each other. However their components in the mid-plane add to each other and have the direction of the projected vector 66.

The pitch circle 57 of pinion 57 intersects the projected vector 66 at 68. If the axis of the mating gear 57 lies on line 61-68, the tooth load exerted on pinion 57 by gear 57' is inclined to its pitch circle 72. This load has to produce a turning moment equal and opposite to that produced by projected vector 66 of both members 51', 51": The peripheral load components are equal. If 68-68 is the force along projected vector 66, 68-68" is a measure of the force along the tooth normal. Distance 68'-68" is parallel to center line 60'-6l and is a measure of the resulting bearing load. It is small.

A still smaller bearing load is attainable when the axis of gear 57' is displaced about axis 61 to a position 60, through an angle 60'-61-60 equal to the angle 68-68-68".

In the actual design the plane 60-61 or 60-61 may be kept horizontal. In other words the gear axis is turned up to 60, while the common plane of the member axes is tilted to 64,. In FIG. 6 gear 57' is turned up into the drawing plane and shown in dotted lines.

The stationary housing comprises

end parts

74, 74"

and a center part 75, all rigidly secured together. The housing has projections for securing it to a base or frame. Outlet and inlet channels are shown in dotted lines only on the end part to the right, as they do not appear directly in this sectional view. Their opening as they meet the spherical outside surface of the intermeshing members has been described with FIG. 1. The ducts otherwise are conventional and are not further shown.

Conventional cooling means may be provided but are not shown. They include fins or channels for liquid cooling.

FIG. 8 shows an application of the described toothed members to an internal combustion unit. It comprises a compressor 76 with a larger toothed member 77 and a smaller one 78. It further comprises an engine or motor 79 with a larger toothed member 80 and a smaller one 81. The pairs of members are as described with FIGS. 1 to 4. The

larger members

77, 80 are coaxially arranged and rigidly connected by means of a toothed face coupling 82 similar to coupling 54in FIG.

6. 83 denotes the axis of the resulting rotor, and 84, 85

are the axes of the

smaller members

78, 81 respectively. The

axes

84, 85 are shown turned into the drawing plane, although the plane of axes 83, 84 does not coincide with the plane of the axes 83, 85, as will be further described.

The rotor is mounted on

bearings

86, 87 in the housing composed of

end parts

88, 88" and connecting part 88. A bevel gear 89 is rigidly secured to the rotor adjacent bearing 87 and motor 79, so that its rearward axial thrust is opposed to the axial thrust exerted on member 80 by the fluid pressure. The axial thrust of the compressor plus the axial thrust of gear 89 may then nearly balance the axial thrust of member 80.

Bevel gear 89 meshes with another bevel gear 90, shown in dotted lines, whose axis 9] lies in a plane perpendicular to the axis 83 of the

coaxial members

77, 80. It is also in a plane containing the axis 83 of

members

77, 80 which plane includes an angle with a plane containing the last-named axis 83 and

axis

84 or 85.

In operation, air is condensed in the compressor at left and channelled into a combustion room, whence it is admitted to the motor at right. Combustion may be either completed in the combustion room, or started there and completed in the motor during expansion. The latter procedure results in lower maximum temperatures. Channelling and combustion spaces are known art and are not shown in detail.

For best results an analysis similar to the one described with FIG. 7 is made. The pressure-force vectors and their intersection with the mid-plane are however individually determined for the two

members

77 and 80, starting out at first from a common plane with

axes

83, 84, 85, and then turning one of the

axes

84, 85

about axis 83 to reduce the bearing load. Then the bevel gear 90 is set about axis 83 to its most favorable position.

The bevel gears or the cylindrical gears may be used in either of the embodiments described with FIG. 6 and with FIG. 8. Furthermore hypoid gears may be used in place of the bevel gears.

What I claim is:

1. A rotary positive displacement unit comprising two pairs of intermeshing toothed members having tooth numbers differing by one,

the axes of said members intersecting at an angle differing from by half the angular height of the teeth, so that the teeth may remain in contact with one another along the entire circumference of said members,

a housing in which said members are rotatably mounted,

ducts for leading fluid to and from the intermeshing members,

the member with the larger tooth number of one pair being coaxial and rigid with the member with the larger tooth number of the other pair,

a shaft for transmitting power,

and an'operative connection between said shaft and said coaxial members bypassing the smaller members of said pairs.

2. A rotary positive displacement unit according to claim 1, wherein said shaft lies in a plane perpendicular to said coaxial members, gears provide said operative connection.

3. A rotary positive displacement unit according to claim 1, wherein said shaft lies in a plane perpendicular to said coaxial members, said operative connection is a pair of bevel gears.

4. A rotary positive displacement unit according to claim 1, wherein said shaft is parallel to the axis of said coaxial members, said operative connection is a pair of cylindrical gears.

5. A rotary positive displacement unit according to claim 1, wherein one of said two pairs of members is the moving part of an internal combustion motor, the other pair is the moving part of an air compressor for feeding compressed air into a combustion chamber and to said motor.

6. A rotary positive displacement unit according to claim 1, wherein the axis of said shaft lies in a plane containing the axis of said larger members, said plane includes an angle with a plane containing the lastnamed axis and the axis of at least one of the smaller members.

7. In a rotary positive displacement unit comprising at least one pair of intermeshing toothed members having tooth numbers differing by one,

the axes of said members intersecting at an angle differing from 180 by half the angular height of the teeth, so that the teeth may remain in contact with one another along the entire circumference of said members,

a housing in which said members are rotatably mounted,

ducts for leading fluid to and from the intermeshing members,

the smaller member of said pair being rotatably supported by a spherical surface portion concentric with the intersection point of said axes and rigid 8. In a rotary positive displacement unit the combination according to claim 7, wherein the projecting portion is tapered, decreasing in diameter in a direction towards said intersection point.

9. In a rotary positive displacement unit the combination according to claim 7, wherein the projecting portion contains an antifriction bearing capable of taking combined radial and axial thrust load.

Claims

1. A rotary positive displacement unit comprising two pairs of intermeshing toothed members having tooth numbers differing by one, the axes of said members intersecting at an angle differing from 180* by half the angular height of the teeth, so that the teeth may remain in contact with one another along the entire circumference of said members, a housing in which said members are rotatably mounted, ducts for leading fluid to and from the intermeshing members, the member with the larger tooth number of one pair being coaxial and rigid with the member with the larger tooth number of the other pair, a shaft for transmitting power, and an operative connection between said shaft and said coaxial members bypassing the smaller members of said pairs.

6. A rotary positive displacement unit according to claim 1, wherein the axis of said shaft lies in a plane containing the axis of said larger members, said plane includes an angle with a plane containing the last-named axis and the axis of at least one of the smaller members.

7. In a rotary positive displacement unit comprising at least one pair of intermeshing toothed members having tooth numbers differing by one, the axes of said members intersecting at an angle differing from 180* by half the angular height of the teeth, so that the teeth may remain in contact with one another along the entire circumference of said members, a housing in which said members are rotatably mounted, ducts for leading fluid to and from the intermeshing members, the smaller member of said pair being rotatably supported by a spherical surface portion concentric with the intersection point of said axes and rigid with the larger member of the pair and further by bearing contact at a region spaced therefrom to one side only of said intersection point, the improvement wherein an external portion is rigid with and projects from the housing towards said intersection point to the inside of said smaller member to provide said further contact, whereby to ease the contact at said spherical surface and to receive the major part of the bearing loads.

8. In a rotary positive displacement unit the combination according to claim 7, wherein the projecting portion is tapered, decreasing in diameter in a direction towards said intersection point.