Conventional positive displacement pumps, and particularly those blower or supercharger units for fitment to engines, include various designs. However, all of these designs may be inefficient in operation and generally require complex sealing arrangements.

Typical examples of previous designs include blower units utilising cooperating tapered screw threads which draw the compressible fluid from one end of the threads and compress the fluid through increasingly tighter pitched threads to the outlet. Such units can only shift the volume of air between the threads and have difficulty in shifting large volumes of air. Furthermore, difficulties in sealing can be present in such units.

A further form of positive displacement pump or blower unit utilises interengaging rotating members, such as gears and rotors, where an adjacent rotating member displaces the fluid in a pocket of an adjacent rotor as the two rotate. In this example, the unit must be capable of housing two adjacent rotating members to shift the volume of air displaced, by one fitting within the other.

OBJECT OF THE INVENTION Therefore, it is an object of one embodiment of the present invention to provide a positive displacement pump which will overcome or at least obviate some of the disadvantages of the previous designs or at least will provide the public with a useful choice.

SUMMARY OF THE INVENTION Accordingly, in a first aspect, the invention may broadly be said to consist in a positive displacement pump including: -a housing; -at least one inlet for the inlet of fluid to be displaced; -at least one outlet for the outlet of fluid displaced; -at least one outer blade mounted with respect to a first axis; -at least one inner rotating member mounted with respect to a second axis offset from said first axis; -a cooperating pocket for the or each outer blade provided on said at least one inner rotating member such that the or each blade may nest within said cooperating pocket throughout a portion of relative movement between said at least one inner rotating member and said at least one outer blade; -a separator mounted with respect to said first axis to seal between said at least one inner rotating member and said at least one outer blade substantially when said at least one outer blade is not nested in said pocket; -said at least one outer blade rotating with respect to said separator about said first axis; and -wherein said at least one inner rotating member rotates relative to said first axis and maintains a substantially constant radial orientation with respect to said at least one outer blade.

In a second aspect, the invention may broadly be said to consist in a positive displacement pump including:

-a housing; -an inlet into said housing for the inlet of fluid to be displaced; -an outlet from said housing for the outlet of fluid displaced; -at least one outer blade rotating with respect to said inlet and outlet about a first axis; -an inner rotating member rotating with respect to said inlet and outlet and rotating about a second axis offset from said first axis and rotating simultaneously with said at least one outer blade and in the same direction and said inner rotating member being wholly within the outermost circumference of rotation of said outer blade; -a cooperating pocket for the or each outer blade provided for said inner rotating member such that the or each blade may nest within said cooperating pocket throughout a portion of the rotation of said outer blade; and -a separator mounted so as to seal between said inner rotating member and said at least one outer blade over a portion of the rotation of said outer blade substantially when said outer blade is not nested within said pocket, said separator being substantially stationary with respect to said inlet and said outlet.

Preferably said separator of the two paragraphs immediately above may include a member having a first surface adjacent a portion of the outer circumference of said inner rotating member and a second surface adjacent an innermost circumference of said outer rotating blade (s).

In one embodiment, said pump is provided as a blower unit for a rotary engine.

In a third aspect, the invention may broadly be said to consist in a positive displacement pump including: a housing; an inlet for the intet of fluid to be displaced; an outlet for the outlet of fluid displaced; -at least one outer blade stationary with respect to said inlet and said outlet and also stationary with respect to a first axis; an inner rotating member mounted on a second axis offset from said first axis with said second axis rotating about said first axis such that said inner rotating member maintains a substantially constant radial orientation with respect to said at least one outer blade; a cooperating pocket for the or each outer blade provided on said inner rotating member such that the or each blade may nest within said cooperating pocket throughout a portion of the relative movement between said at least one outer blade and said inner rotating member; a separator mounted about said first axis to rotate about said first axis relative to the or each outer blade such that said separator nests between said inner rotating member and the or each said outer blade over a portion of the movement of said inner rotating member when the or each said outer blade is not nested within said pocket; and timing means to time the rotation of said inner rotating member with respect to said first axis and said separator about said first axis such that both said inner rotating member and said separator maintain the same rotational speed and in the same direction.

Further aspects of this invention which should be considered in all its novel aspects will become apparent to those skilled in the art upon reading the following description.

BRIEF DESCRIPTION OF THE DRAWINGS Preferred embodiments of the invention will now be described with reference to the drawings in which: FIGURE 1: is a cross-sectional side elevation through a pump in accordance with one embodiment of the invention; FIGURE 2: is a cross-sectional front elevation of the pump of Figure 1; FIGURE 3: is a further cross-sectional elevation of the pump of Figure 1; FIGURE 4: is a diagrammatic view of a series of front elevations of the pump showing approximately one half a revolution of the pump; FIGURE 5: is a diagrammatic view of a series of elevations as provided in Figure 4 showing a further one half revolution of the pump; FIGURE 6: is a cross-sectional front elevation through a further embodiment of the invention; FIGURE 7: is a cross-sectional side elevation through the embodiment of Figure 6; FIGURE 8: is a front view of the embodiments of Figure 7 showing the gearing;

FIGURE 9: is a front view of a further embodiment of the invention; and FIGURE 10: show a diagrammatic view of a series of front elevations of the pump of Figure 6 during one revolution.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Referring to the drawings Figures 1 to 5, the invention can be seen to reside in a pump having at least one outer rotating blade 1. In this embodiment, the pump will include at least two blades 1 and, in the embodiment shown in the drawings, three blades 1 are provided substantially equally positioned around the perimeter of the pump.

The outer rotating blades 1 are provided as part of a circumferential rotating cylinder 7 that rotates about a first axis defined by the main bearings 14 and 16 being a small and large main bearing respectively.

The pump includes an inner rotating member 2 rotating within the outer rotating cylinder 7 to which the blades 1 are connected. The inner rotating member 2 rotates about a second axis offset from the first axis.

This second axis is defined by the shaft 5 extending through the inner rotating member or rotor 2.

A pocket 26 is provided within the inner rotating member 2 for each of the blades 1 rotating with the inner rotating member 2.

As will be explained later in more detail, the blades 1 and inner rotating member 2 are provided on offset axes although linked to ensure that they rotate simultaneously at the same rotational speed and in the same direction.

It can be seen that the blades 1 nest within the pockets 26 throughout a portion of the rotation of the blades 1 and inner rotating

member 2. However, due to the offset nature of the axis about which they turn and the relative diameters, the blade 1 is also withdrawn from its associated pocket 26 through a portion of the rotation.

It can be seen that the inner rotating member 2 is wholly within the outermost circumference of the blades 1 defined by the inner circumference of the cylinder 7 supporting the blades 1.

A separator 3 or shoe is provided between the inner rotating member 2 and the blades 1 over a portion of the blade rotation when the blades 1 are withdrawn from the pockets 26. It can be seen that this shoe 3 will have a side 27 substantially adjacent to and conforming to the outermost circumference of the inner rotating member 2. A further side 28 is adjacent and conforms to the innermost circumference of rotation of the blades 1 as defined by the arcuate travel of the tip 29 of the blades 1 through this region. The separator 3 is thus shown in this embodiment with a substantially crescent-shaped cross section.

An exterior housing 4 may be provided around this entire apparatus should this pump which, in this preferred form, is provided as a blower unit, is provided as a stand alone apparatus.

Side plates 8 may also be provided to provide containment to the chambers defined by the pockets 26 and the blades 1 within the outer cylinder 7.

In this particular embodiment, an air gap 9 is provided between the outer rotating cylinders 7 and the housing 4.

As shown in Figure 1, an inlet vacuum pipe 20 and outlet pressure pipe 21 are provided and are in communication with the vacuum port 12 and pressure port 11 respectively as shown in Figure 2.

Referring to Figure 3, one possible drive unit with possible timing and linkage arrangements are shown. The second axis defined by the rotor shaft 5 is shown in the centre of a drive unit 10. This drive unit

10 terminates in pivotal connections 17 linked by link members 6 to similar pivotal connections 17A provided on the blades 1. Each of the pivotal connections 17 includes a drive pin at or adjacent a respective drive end of arm 10A and the link member 6 can include apertures at either end to fit over the drive pins of pivotal connections 17 and 17A.

Preferably a bearing such as a needle roller bearing is provided on the drive pins of pivotal connections 17,17A or in the inner circumference of the apertures at the ends of the links 6 to allow relative rotation.

The position of the first set of pivotal connections 17 at the ends of the arms 10A of the drive member 10 is such as to provide these equidistant from the second axis of rotation 5. Furthermore, the second set of pivotal connections 17A provided on the blades 1 are equidistant from the centre of rotation of the first axis being the centre of rotation of the blades 1. This form of linkage allows the blades 1 and the inner rotating member 2, mounted on the first and second axis respectively, to rotate simultaneously in the same direction at the same rotational speed.

The rotation of both the blades 1 and the inner rotating member 2 can be driven from either of the axes and through the links 6 and drive unit 10 to the other axis. In this instance, the drive may be supplied by an application of a rotational drive to the drive gear 30, although in other applications, any drive applied to the drive unit 10 through either axis will drive the other axis simultaneously.

As an alternative to the links 6 and drive unit 10 described in this preferred form of the invention, the drive and timing equipment could utilise gears or other timing and drive chains to ensure the simultaneous rotation about the first and second axis in the same direction and at the same rotational speed.

Also shown in Figure 3 are optional valves 18 and 19. These may be provided to act as valves between the chambers defined by the blades 1, rotor 2 and side plates 8 and the inlet and outlet ports 12,11.

In this preferred form, the valve 18 is a vacuum spring valve and the valve 19 a pressure spring valve. However, the valves may be dispensed with entirely in some arrangements or alternative valve constructions can easily be used.

This particular embodiment has described inlet and outlet ports 12,11 which are substantially stationary with respect to the separator 3 while said blades 1 and rotor 2 rotate. Rather than using the stationary ports as described, the apparatus could be ported with rotary ports or ported through the blades 1. An example of porting through the blades 1 is described in the alternative embodiment described in Figures 6 and 7.

Referring to Figure 4, the commencement of the formation of a vacuum chamber for the induction of air into the unit is shown. This is shown by the shaded area 22 defined between the inner rotating member 2 and one of the outer blades 1. Moving from the left side of Figure 4 to the right, across the top row of diagrammatic views, it can be seen that as the blades 1 and inner member 2 rotate, the vacuum chamber 22 slowly expands within that pocket, identified generally by arrow 26 and as defined between the blade 1 and the inner member 2.

It can be seen that during the simultaneous rotation of the outer blade 1 and the inner member 2, the blade 1 progresses from one side of the pocket 26 to the other in the direction of rotation of the blades, and inner member 2 and the pocket 26 and blades 1 are provided such that the blades 1 seal against the surface of the pocket 26 through minimal clearance provided between these. As the area 22 continues to expand forming the vacuum chamber, it reaches a point shown by the shaded area 32 halfway through the formation of this pocket 26 at which the blade 1 begins to clear the pocket 26. It is at this point that the separator or shoe 3 acts to split the vacuum area 22 effectively into two portions defined by the shaded areas 23 and 24 shown in the last diagram in Figure 4.

Now turning to Figure 5, the compression of the air is shown. As can be seen by comparison with the last diagram of Figure 4 and the first diagram of Figure 5, the air within the pocket 23 once moving into the compression phase is timed to join with the pocket 24 between the preceding two blades 1 from that from which it was separated throughout Figure 4. This occurs as the blade 1 moves behind the shoe 3 and rejoins the pocket 26 on an alternate side of that pocket. The

progression of this pressure chamber can be seen throughout the diagrams in Figure 5 shown by the shaded portions as the areas 23 and 24 are compressed to finish in the small area 25 shown in the last of the diagrams. The diagrams show equal rotational movements of the components throughout a further half full revolution of the apparatus and are to be read left to right across each row respectively.

It can be seen that in operation the pump acts as a positive displacement pump creating a vacuum chamber and a pressure chamber.

The pump operates around the outer circumference of the inner rotating member 2 and within the outer rotating member 7. It operates against the full circumference of the outer rotating member 7.

Because of the tortuous paths for the fluid in the pump, it has been found that complex seals between the components are not required.

Referring to Figure 6, a further embodiment of the invention is shown. In this embodiment, the blade 1 is stationary with respect to the outlet port 11 and the inlet port 12. These ports 11 and 12 may be provided in the blade 1 itself.

Rather than the blade 1 rotating, the separator 3 may rotate about a first axis being substantially central within the outer housing 4.

The inner rotating member or rotor 2 is mounted on its own second axis which moves rotationally about the first axis. As the second axis moves about the first axis, the rotor 2 maintains a substantially constant radial orientation with respect to the blade. This is illustrated in Figures 10 and 11 especially. In the example shown, the pocket 26 will remain substantially facing towards the blade 1 as the entire rotor 2 moves about the central axis.

Throughout this movement, the tips 33 of the rotor 2 adjacent the pocket 26, such as tip 33, open and close the various chambers being formed within the pump from access to the ports such as the inlet

port 12. As shown in Figure 6, initial movement of the rotor 2 about a central axis moves the tip 33 across the inner surface of the housing 4 containing the blade 1 to gradually open the area formed by the blade 1, the surface of the pocket 26 and the tip 33, to the inlet port 12. Again, this is illustrated in Figure 10 especially referred to in greater detail below.

Turning to Figures 7 and 8, it can be seen that gears 34,35 and 36 and associated idlers may be utilise to ensure the simultaneous rotation of the rotor 2 and the separator 3 about the central axis. Both are moving in the same direction, for example clockwise, about the central axis and at the same rotational speed such that both assume the position shown in Figure 6 after a 360° revolution about said central axis.

In this particular embodiment, only a single blade 1 and single pocket 26 has been shown on the rotor 2. Of course, multiple blades 1 and a corresponding number of pockets 26 could be provided if desired.

Furthermore, although the description generally refers to a single inner rotating member or rotor 2, there coutd be a plurality of members defining the pockets 26, and the regions intermediate of the pockets 26, where the rotor 2 must seal against the other appropriate parts of the pump.

If an embodiment as shown in Figures 6 and 7 is to include multiple blades 1, a number of inlets and outlets 12 and 11 might be required with at least one inlet and at least one outlet being provided for each blade 1.

Referring to Figures 10 and 11, a full cycle is shown of the pump of Figure 6. It is seen that as rotor 2 and shoe 3 both rotate simultaneously, the area or chamber 22 expands until with the rotor 2 distant from the blade 1, shoe 3 will move across the blade 1 to close off a portion of the area 22 to transfer that portion of air 23 to the compression side. As the cycle continues, the rotor 2 will then act to compress the air in front of it, as seen particularly in Figure 11, with the

areas 23 and 24 being compressed into the same area 25 as shown in the last of the diagrams.

In Figure 9, a pair of rotors 2 are shown provided in this embodiment rotating with shoe or separator 3 relative to a single blade 1. This embodiment can be of advantage in balancing the rotational forces present in the pump and providing a smoother output. This pump will operate as described with respect to Figures 10 and 11 apart from the additional capacity provided by the additional rotor 2.

It should also be noted that all the embodiments of this invention are described as a pump to increase pressure creating a vacuum at the inlet and a pressurised fluid at the outlet. Of course, all such embodiments could be reversed to create a vacuum at the outlet if desired.

Furthermore, the description of all embodiments generally refers to moving or stationary parts. However, it is the relative movement of the parts which is essential to the pump's function and these can be reversed in any particular embodiment so that the stationary parts move and the moving parts are stationary.

In addition to being used as either a vacuum or a pressure pump, pumps generally also have the facility to act as motors. For example, a pressurised fluid could be supplie to the embodiments shown and drive drawn from the embodiments rather than drive being supplie to the embodiments to operate them as a pump.

In a yet further variation, these embodiments in which expanding and contracting chambers are provided for the expansion or compression of fluids within the chambers, could be utilise as a combustion motor should a fuel and ignition mix be supplie to the chamber to drive the expansion of the chamber and may be exhausted through the current outlet ports. In this manner the same arrangement may be used to provide a combustion motor rather than a pump.

As shown in this preferred form, the pump can be used as a blower unit although it can be used in all other situations that pumps of this type may be desired.

One particular use of this blower unit is in conjunction with a rotary engine such as that described in international application No. PCT/ NZ95/00015. The motor described in that international specification utilises the same off axis rotation between the centre of rotation of the housing of the motor and the centre of rotation of the pistons.

Therefore, this simultaneous timed drive of the two components is already provided and the drive can be utilise directly into the blower unit to rotate the blades and inner rotating members respectively.

Although the preferred form of this invention described refers to an independent blower unit, the combined engine and blower unit may substantially save on componentry from this stand alone unit due to the drive being able to be accessed directly. Such a blower unit may be bolted directly onto the end of such a motor utilising the same two axes of rotation as the motor does.

Thus it can be seen that this invention provides a pump which provides an efficient displacement of fluids and, in particular, compressible fluids.

Where in the foregoing description reference has been made to specific components or integers of the invention having known equivalents then such equivalents are herein incorporated as if individually set forth.

Although this invention has been described by way of example and with reference to possible embodiments thereof it is to be understood that modifications or improvements may be made thereto without departing from the scope of the invention, as defined in the appended claims.