Rotary Fluid Pump Or Motor With Intermeshed Spiral Walls

Abstract

A fluid pump has two sets of spiral pumping units operating in parallel, one pumping spirally outward and the other spirally inward. Each unit consists of a pair of spiral walls intermeshed between end walls which are pressed towards each other by outlet fluid pressure to obtain good sealing action. The intermeshed spiral walls engage each other along lines of contact which advance spirally, being driven by a rotary drive which, in response to dynamic pumping forces, causes the spiral walls to maintain contact despite wear. The fluid pump can act as a motor when fluid under pressure is forced through the spiral units.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a fluid pump or motor of the kind having intermeshed spiral walls.

2. Description of the Prior Art

Fluid pumps with a pumping action produced by spiral walls have been known for some time but with many of the previous pumps the output was not smooth, or the drive was complex, or there were leakage problems. These disadvantages can be overcome with the present invention.

SUMMARY OF THE INVENTION

A relatively smooth pump output can be achieved by operating two spiral pumping units in parallel, one pumping spirally outward and the other spirally inward. Fluid outlet pressure is utilized to reduce internal leakage. A drive, responsive to dynamic pumping forces, maintains the spiral walls in contact so that wear of the spiral walls does not cause internal leakage. The operation of the units can be reversed for operation as a fluid motor.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings which illustrate a preferred embodiment of the invention:

FIG. 1 is a sectional view of a fluid pump;

FIG. 2 is a sectional view along the line 2--2 of FIG. 1;

FIG. 3 is a sectional view along the line 3--3 of FIG. 1, with a fluid inlet indicated partly in phantom lines;

FIG. 4 is a sectional view along the line 4--4 of FIG. 1, with the fluid inlet indicated in phantom lines;

FIGS. 5, 6, 7 and 8 are schematic views showing successive positions of spiral walls of a pumping unit during one revolution of its rotary drive, FIG. 8 showing a position corresponding to FIG. 3; and

FIG. 9 is an exploded view of a modification of part of the pump.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring first to the schematic FIGS. 5 to 8, these show a stationary housing 1 within which is a pair of identical spiral walls, namely a stationary spiral wall 2 and a movable spiral wall 3. The walls 2, 3 are fitted together approximately 180.degree. out of phase with each other. The stationary spiral wall 2 has an axis 4, and the axis of the spiral wall 3 is offset from the axis of the spiral wall 2 by an amount equal to the radius of a circle 5. The wall 3 is oscillated in a circular path so that its axis follows the circle 5 in the direction of the arrow thereon, but the 180.degree. relationship of the walls is maintained, i.e., the wall 3 does not rotate about its axis. The offset of the two axes is such as to cause the walls 2 and 3 to contact each other along two lines 6 and 7 normal to the paper, and as the wall 3 moves from the position shown in FIG. 5 through those shown in FIGS. 6, 7 and 8 the lines of contact 6 and 7 move spirally outward, until in the position of FIG. 8 new lines of contact 6' and 7' begin near the axes, and these in turn progress spirally outward as the circular oscillation of the wall 3 is continued. These new lines of contact 6', 7' are picked up shortly before the lines 6, 7 disappear because each spiral has slightly more than 11/2 turns, i.e., each spiral extends slightly more than 3.pi. radians. As wear occurs it may not be possible to maintain good contact at all four lines 6, 7 and 6', 7', but while one pair of these lines are in tight contact it is not necessary the others be in tight contact. Although spiral walls of greater length than those illustrated could be used, with the object of having at all times more than two lines of contact between the walls, the fabrication of the walls would require great accuracy.

If fluid is continuously admitted adjacent the axes of the spiral walls and is confined between these walls, the oscillation of the wall 3 causes the fluid to be pumped spirally outward as the lines of contact between the walls advance spirally outward.

The pump illustrated in FIGS. 1 to 4 includes two pumping units one of which operates by pumping spirally outward as schematically shown in FIGS. 5 to 8 and the other of which operates by pumping spirally inward.

In FIG. 1, a pump assembly is enclosed between end portions 8, 9 of a housing, the end portion 9 being held by bolts 10 to a main body member 11 on which the end portion 8 removably fits. Stationary end walls 12, 13 extending transversely of the housing create a first chamber 14 between end wall 12 and end wall 13, and a second chamber 15 between end wall 13 and the end portion 9 of the housing. Thus, end wall 13 forms a common wall between the two chambers 14, 15, and since, as will be explained, there is fluid pressure on both sides of this wall, gaskets 13a are provided around its periphery. A stationary spiral wall 16 and a movable spiral wall 17 are contained in the first chamber 14 and a stationary spiral wall 18 and a movable spiral wall 19 are contained in the second chamber 15, these walls being seen in transverse section in FIGS. 3 and 4, where it can be seen that the spiral walls of each pair are fitted together 180.degree. out of phase from each other. As can be seen in FIG. 1, the spiral walls 16, 17, 18, 19 are each fast along one of their longitudinal edges with end walls 12, 20, 13, 21 respectively, the other longitudinal edge of each spiral wall 16, 17, 18, 19 bearing frictionally along the inner surface of end wall 20, 12, 21, 13 respectively.

In the position shown in FIGS. 1, 3 and 4, each pair of spiral walls has four lines of contact but, as stated above with reference to FIG. 8, this is only a momentary position due to the length of the spiral walls being slightly greater than 11/2 turns or 3.pi. radians; at most times there are only two lines of contact between each pair, as indicated schematically in FIGS. 5, 6 and 7. For the first pair 16, 17, in the position of FIG. 1, there are four lines of contact 22, 23, 22', 23' and for the second pair there are four lines of contact 24, 25, 24', 25'. A first pumping unit is provided by the intermeshed spiral walls 16, 17 and their end walls 12, 20, and another pumping unit is provided by the spiral walls 18, 19 and their end walls 13, 21, and as will be seen these units work in parallel. Spiral wall 17 can be driven to move, relative to spiral wall 16, to advance lines of contact 22', 23' spirally outward from a fluid inlet 26. As viewed in FIG. 3, the spiral wall 17 is driven so that its axis travels in the circle 5 about the axis 4 of the stationary spiral wall 16. Simultaneously, as viewed in FIG. 4, the spiral wall 19 is driven in the same sense as the wall 17, its axis travelling in an identical circle 5 about the axis 4 common to stationary walls 18 and 16. The walls 17 and 19 do not rotate about their axes; they always remain 180.degree. out of phase to the stationary spiral walls 16 and 18 with which they are intermeshed. The spiral pitch of the spiral walls 18, 19 is opposite to that of the walls 16, 17 (the walls 18, 19 being a mirror image of the walls 16, 17), and as spiral wall 19 moves relative to spiral wall 18 the lines of contact 24', 25' advance spirally inward from a fluid inlet 28 to a fluid outlet 29. Thus, the first pair of spiral walls 16, 17 pump fluid from the inside to the outside and the second pair of spiral walls 18, 19 pump fluid from the outside to the inside. The outlet 29 from the second pumping unit of FIG. 4 leads, as seen in FIG. 1, into the chamber 14 of the first pumping unit, and it is into this chamber that the first pumping unit discharges its output, so that the two pumping units have their outlets in parallel, leading to a common outlet pipe connection 30. The inlets 26, 28 are similarly in parallel, having a common inlet pipe connection 31. Each of the pumping units has a pulsating output, of saw-tooth configuration if plotted against time, but the parallel arrangement of the units produces a smooth (i.e., nonpulsating) output at outlet 30, this output being the sum of two sawtooth outputs. Since the dimensions of the spiral walls 16, 17, 18, 19 are fixed, the same quantity of fluid is pumped for each oscillation of the pump regardless of the difference between inlet and outlet pressures, assuming that an incompressible fluid is being pumped.

A peripheral sealing portion 32 is added to the movable end wall 21, dividing the second chamber 15 into compartments 33, 34 at opposite sides of the movable end wall 21, the second spiral pair 18, 19 being in compartment 33. A port 21a through the wall 21 allows the outlet fluid near the axes of the second pair of spiral walls to flow from compartment 33 to compartment 34 where it urges the movable end wall 21 and therefore the spiral wall 19 against the end wall 13 of the stationary spiral wall 18. Also, end wall 21 is urged against the longitudinal edge of spiral wall 18. The outlet fluid in chamber 14 (i.e., in the part of the first chamber 14 where the fluid outlet from the first pair of spiral walls 16, 17 is located) exerts pressure on end wall 20 of the spiral wall 17, urging the latter against the end wall 12 of the stationary spiral wall 16. Thus, leakage is minimized and in fact leakage decreases with wear.

In order to oscillate the spiral walls 17, 19 relative to the spiral walls 16, 18 respectively, in the desired manner, there is provided a shaft 35 which pivots at a ball joint bearing 36 on the axis of the stationary spiral walls 16, 18 and is coupled to spiral walls 17, 19 at a ball joint bearing 37. The shaft 35 is driven, by means described below, in a conical path having its apex at the bearing 36, so that the bearing 37 moves in a circular path. The center of bearing 37 is coincident with the axes of the movable spiral walls 17, 19 and describes the circle 5 of FIGS. 3 and 4 as it moves. Ball joints 36, 37 are seated in ball seats 38, 39 respectively. Ball seat 39 is surrounded by a cylindrical sleeve 40 fast with the end wall 21. Ball seat 39 is slidable in sleeve 40 and may be prevented from rotating relative thereto by pins 41. Movable end wall 20 is fast with a sleeve 42 telescoped onto the sleeve 40 and slidable thereon, but pins 43 fixed in the sleeve 40 extend into longitudinal slots 44 in the sleeve 42, preventing relative rotary movement between the sleeves.

Screwed into the end of sleeve 40, and pinned thereto by a radial pin 45, is a ring 46, and compressed between the ring 46 and bearing seat 39 is a coil spring 47. By reacting against the bearing seat 39 the spring presses the ring 46 and thus the sleeve 40 and end wall 21 and spiral wall 19 in a direction holding the spiral wall 19 against the end wall 13, to bear frictionally thereagainst. In compression between the end walls 21 and 20 is a weaker spring 48 which, reacting against the wall 21 presses the spiral wall 17 against the stationary wall 12 on which it frictionally bears. The purpose of these springs 47, 48 is to allow for tolerances in the construction of the parts making up the spiral pump units, and to minimize leakage during start-up of the pump when there is little or no outlet fluid pressure to urge the movable spiral walls 17, 19 against the stationary end walls 12, 13 respectively.

The ball seat 38 is fixed in a cylindrical hub 50 fastened by studs 51 to a cylindrical portion 12a of the transverse wall 12. To provide a fluid-tight seal between the wall 12 and the sleeve 40, a bellows 52 is affixed at one end to the ring 46 and at the other end to a sealing disc 53 sandwiched between the wall portion 12a and the hub 50. The sealing bellows 52 around the shaft 35 prevents the fluid being pumped from entering the area of the bearing 36, and at the same time act as a detent to prevent relative rotation between the stationary end walls 12, 13 and the movable end walls 20, 21, and thus between the spiral walls 16, 17, 18, 19. Thus, as the bearing 37 moves in a circular path, the movable spiral walls 17, 19 oscillate relative to the stationary spiral walls 16, 18 but do not rotate relative thereto.

A rotary drive is provided by a shaft 54 of a prime mover (not shown). The shaft 54 extends through the housing end portion 8, and has an enlarged drive member or disc 55 having a cylindrical extension 56 centered by bearings 57 on the hub 50. The shaft 35 has an end 35a, opposite to that of the ball joint bearing 37, mounted in a bearing 58, and the bearing 58 is located in a guideway or slot 59 in the rotary drive member 55, as best seen in FIG. 2. The slot 59 has a center line 59a which is not quite radial to the drive member 55, the line 59a being slightly offset from the rotary axis 55a of the drive member. A radial line 55b through the axis 55a and the center line 35b of the shaft makes an angle p with the center line 59a of the slot 59. The bearing 58 is free to slide along the slot 59, and is biased away from the rotary axis 55a by a compression spring 60 in the slot. As the drive member 55 rotates, the end 35a of the shaft 35 is driven in a circular path around the axis 55a, so that the shaft 35 is forced to move in a conical path with its apex at the bearing 36. With the shaft end 35a urged in the direction in which it is pressed by the spring 60, the other end 37 of the shaft is urged to establish lines of contact between the movable spiral walls 17, 19 and their respective stationary partners 16, 18.

As fluid is pumped, the total dynamic head thereof is transmitted by the movable spiral walls 17, 19 through the shaft 35 to the bearing 58 which is eccentrically positioned relative to the rotary drive member 55. As shown in FIG. 2, the transmitted force F due to the dynamic head is at right angles to the radial direction of eccentricity along line 55b. Since the slot 59 is at an angle p to the radial line 55b through the center-line of the shaft 35, the force F has a component f which tends to urge the bearing 58 along the slot 59 towards the outer edge of the rotary drive member 55. This component force f is transmitted through the shaft 35 to the movable spiral walls 17, 19. As the spiral walls wear, this component force f increases the orbit of the movable spiral walls 17, 19 so that they are urged both by the spring 60 and by force f, to maintain contact with the stationary walls 16, 18 respectively. Therefore, wear of the spiral walls does not cause leakage. As wear continues it may not be possible to maintain all four lines of contact for each pair of spiral walls, in the position shown in FIG. 1. However, it is sufficient for the efficient operation of the pump if two lines of contact are maintained for each pair. The spring 60 serves to establish lines of contact when the total dynamic head of the pump is low or negative; as a dynamic head builds up, the force f also builds up.

The thicknesses of the spiral walls is preferably less than the radius of the circle 5, if the pump is to handle materials carrying solid particles: if a particle should be caught between a longitudinal edge of a spiral wall and the end wall against which it bears, movement of the spiral wall by more than twice its own thickness should lead to the reexposure of the particle to the fluid being pumped.

The bellows 52 of FIG. 1 seals the fluid being pumped from lubricating oil in the shaft system, and should be a metallic bellows to serve as a detent which, while permitting orbital (oscillating) movement of the walls 17, 19, prevents rotation thereof around their axes. Foreign matter passing through the pump might cause it to bind, imparting an abnormal torque which would twist the bellows 52 to destruction, and to deal with this problem an alternative detent mechanism is shown in FIG. 9, the proportions being somewhat distorted for facility of illustration. In this arrangement, a fixed ring 53' can be fastened to the stationary wall portion 12a of FIG. 1, and an orbital ring 40' can be fixed to the sleeve 40. Between these rings 53', 40' is a detent ring 61, and when the mechanism is assembled projections 62 of the detent ring 61 fit into radial slots 63 of the fixed ring 53' and projections 64 of the detent ring fit into radial slots 65 of the orbital ring 40', the projections fitting snugly in the slots but being slidable radially thereof. The projections 62 and 64 are on diameters at right angles to each other, and permit orbital movement of ring 40' while preventing rotation about its axis, thereby preventing rotation of the orbital mechanism of which it is a part. A bellows 52' can be affixed to the rings 40' and 53' by clamping screws 66 which are not exposed to the fluid within the pump, the bellows isolating that fluid from the shaft and driving mechanisms. (A ring, not shown, will be laid over the flange 52a' of the bellows to clamp it against the ring 40', and the flange 52b' will be clamped between the ring 53' and a stationary casing member, for example, the wall portion 12a of FIG. 1). Because the bellows need not provide a detent action, and twisting of the bellows is prevented by the detent ring 61, the bellows can be made of elastomeric material having long fatigue life and good corrosion and wear resistance. The bellows may be of large diameter, permitting the use of a large drive shaft and ball joints for higher ratings. The bellows preferably has helical convolutions, and can be supported by a helical spring (Not shown) within its convolutions to increase its pressure rating.

When the device is operated as a motor the operation heretofore described is reversed. Fluid under pressure is forced into what was the outlet connection 30. The fluid forces the spiral walls of each pair to move relative to each other in the opposite direction to that when operated as a pump. The inlet pressure (at connection 30) is higher than the outlet pressure (at connection 31) and acts on the undersides of the end walls 20, 21 to inhibit leakage. The fluid drives the spiral walls which in turn drive what was the drive means when operated as a pump. Since the rotary member 55 is caused to rotate in the opposite direction to that indicated in FIG. 2, the direction of the slot 59 must be at a negative angle p to the radial line 55b through the centreline 35b of the shaft 35 (i.e., line 59a must be counterclockwise from line 55b) in order that the component force f can have the same leakage-inhibiting effect as it has when the embodiment is operated as a pump.

Claims

What we claim as our invention is:

1. A fluid pump or motor comprising a first pair of spiral walls and a second pair of spiral walls, the walls of each pair being fitted together out of phase between end walls perpendicular to the spiral walls, with two lines of contact between the spiral walls of each pair, means for moving one spiral wall of each pair relative to the other spiral wall of the same pair, while maintaining said out of phase relationship, to advance said lines of contact spirally outward, for the first pair, from a fluid inlet to a fluid outlet, and spirally inward, for the second pair, from a fluid inlet to a fluid outlet, whereby fluid flows spirally outward between the first pair and spirally inward between the second pair, the fluid inlets being in parallel and the fluid outlets being in parallel whereby the total flow through the pump or motor is the sum of said spirally outward and inward flows, the sizes and configurations of the first and second pairs of walls being substantially identical whereby said sum is substantially nonpulsating.

2. A fluid pump or motor as claimed in claim 1 wherein each spiral wall extends approximately 3.pi. radians.

3. A fluid pump as claimed in claim 1 wherein the walls of each pair are fitted together approximately 180.degree. out of phase.

4. A fluid pump or motor as claimed in claim 1 wherein each spiral wall has two longitudinal edges, one longitudinal edge of one spiral wall of each pair being fast with one end wall, the other longitudinal edge of the latter spiral wall bearing frictionally along an opposite end wall, one longitudinal edge of the other spiral wall of the pair being fast with said opposite end wall and the other longitudinal edge of the latter spiral wall bearing frictionally along said one end wall.

5. A fluid pump or motor as claimed in claim 4 wherein one spiral wall and end wall of each pair are stationary, and the other spiral wall and end wall of the pair are movable by said moving means.

6. A fluid pump or motor as claimed in claim 5 wherein the moving means comprise a shaft pivoted for movement in a conical path, rotary means for driving the shaft in said conical path, and means coupling the shaft with the movable wall of each pair.

7. A fluid pump or motor as claimed in claim 6 wherein the coupling means comprise a bearing into which one end of the shaft extends and on which the movable spiral walls are driven in circular paths of the same size.

8. A fluid pump or motor as claimed in claim 5 wherein the movable one of the end walls of each pair has an outer surface subjected to the pressure at the fluid outlet whereby it is fluid pressed towards the stationary end wall of the same pair.

9. A fluid pump or motor as claimed in claim 8 wherein, for the second pair of spiral walls whose lines of contact advance spirally inward from a fluid inlet to a fluid outlet, the movable end wall has a port through which outlet fluid can flow to exert pressure against the outer surface of said end wall, said end wall having an inner surface and a peripheral sealing portion that confines inlet fluid pressure to said inner surface.

10. A fluid pump or motor as claimed in claim 8 and including spring means urging the movable end wall of each pair towards the stationary end wall.

11. A fluid pump or motor comprising a pair of substantially identical spiral walls fitted together approximately 180.degree. out of phase between end walls perpendicular to the spiral walls, with two lines of contact between the spiral walls, means for moving one spiral wall relative to the other, while maintaining said phase relationship, to advance the said lines of contact spirally from a fluid inlet to a fluid outlet, said means comprising a shaft pivoted for movement in a conical path, means coupling the shaft with said one of the spiral walls, a rotary drive member for driving the shaft in said conical path, the rotary drive member having an outer edge and a guideway extending towards said outer edge and engaging the shaft, the shaft having a center line intersected by a radius of the rotary drive member, and the guideway being at an angle to said radius whereby a dynamic force on the shaft normal to said radius has a component along the guideway urging the shaft to move in a direction along the guideway to press together the spiral walls.

12. A fluid pump or motor as claimed in claim 11 wherein one of the end walls has an outer surface subjected to the pressure at the fluid outlet whereby it is fluid pressed towards the other end wall.

13. A fluid pump or motor as claimed in claim 11 wherein the guideway comprises a slot, and a spring in the slot urges the shaft in said direction along the slot.

14. A fluid pump or motor as claimed in claim 13 wherein the shaft is located in a bearing located in and slidable in the slot, the bearing being pressed in said direction by the spring.

15. A fluid pump or motor as claimed in claim 11 wherein the means coupling the shaft with said one of the spiral walls comprise a bearing into which one end of the shaft extends and on which said one of the spiral walls is driven in a circular path.

16. A fluid pump or motor as claimed in claim 15 wherein said one of the spiral walls is fast with one of the end walls and is urged to bear frictionally against the other end wall by a spring supported by said bearing.

17. A fluid pump or motor as claimed in claim 15 and including another pair of substantially identical spiral walls also fitted together approximately 180.degree. out of phase between end walls perpendicular thereto, and with two lines of contact between the spiral walls of said other pair, the spiral walls of said other pair being of opposite pitch to the first mentioned pair, one of the spiral walls of said other pair being driven by said bearing in a circular path, in the same sense as the driven spiral wall of the first mentioned pair, to advance the lines of contact of said other pair spirally from a fluid inlet to a fluid outlet, one of the spiral walls of each pair being stationary.

18. A fluid pump or motor as claimed in claim 15 wherein the shaft is pivoted, for movement in said conical path, in a bearing located between said one end of the shaft and said rotary drive member, and a flexible bellows around the shaft isolates the shaft and bearings from the fluid being pumped.

19. A fluid pump or motor as claimed in claim 18 wherein said phase relationship is maintained by a detent ring within the bellows which prevents twisting of the bellows during said relative movement of the spiral walls.

20. A fluid pump or motor comprising a first pair of spiral walls substantially identical to each other, and a second pair of spiral walls substantially identical to each other, the walls of each pair being fitted together approximately 180.degree. out of phase between end walls perpendicular to the spiral walls, with two lines of contact between the spiral walls of each pair, means for moving one spiral wall of each pair relative to the other spiral wall of the same pair, while maintaining said phase relationship, to advance said lines of contact spirally outward, for the first pair, from a fluid inlet to a fluid outlet, and spirally inward, for the second pair, from a fluid inlet to a fluid outlet, the inlets being in parallel and the fluid outlets being in parallel, each spiral wall having two longitudinal edges, one longitudinal edge of one spiral wall of each pair being fast with one end wall, the other longitudinal edge of the latter spiral wall bearing frictionally along an opposite end wall, one longitudinal edge of the other spiral wall of the pair being fast with said opposite end wall and the other longitudinal edge of the latter spiral wall bearing frictionally along said one end wall, one spiral wall and end wall of each pair being stationary, and the other spiral wall and end wall of each pair being movable by said moving means, the movable spiral walls being coaxially arranged on a common bearing of said moving means, the stationary end wall of the first pair being a wall of a first chamber surrounding the movable end wall and the spiral walls of the first pair, the fluid inlet for the first pair being through said stationary chamber wall near the axes of the spiral walls, and the advance of the lines of contact of the first pair spirally outward delivering fluid to part of said surrounding first chamber where the fluid outlet for the first pair is located and where the outlet fluid pressure urges the movable end wall of the first pair towards said stationary chamber wall, the stationary end wall of the second pair being a common wall of the first chamber and of a second chamber surrounding the movable end wall and the spiral walls of the second pair, the movable end wall of the second pair having a peripheral portion that divides the second chamber into two compartments at opposite sides of the movable end wall of the second pair, the second pair of spiral walls being in one of said compartments, the fluid outlet for the second pair being from said one compartment through said common wall into the first chamber near the axes of the spiral walls, the fluid inlet for the second pair being into said one compartment and the advance of the lines of contact of the second pair delivering fluid spirally inward from said fluid inlet of the second pair to said fluid outlet thereof, the movable end wall of the second pair having a port through which outlet fluid can flow to the other of said compartments where it urges the movable end wall of the second pair towards said common wall.

21. A fluid pump or motor comprising a first pair of spiral walls substantially identical to each other, and a second pair of spiral walls substantially identical to each other, the walls of each pair being fitted together approximately 180.degree. out of phase between end walls perpendicular to the spiral walls, with two lines of contact between the spiral walls of each pair, means for moving one spiral wall of each pair relative to the other spiral wall of the same pair, while maintaining said phase relationship, to advance said lines of contact spirally outward, for the first pair, from a fluid inlet to a fluid outlet, and spirally inward, for the second pair, from a fluid inlet to a fluid outlet, the inlets being in parallel and the fluid outlets being in parallel, each spiral wall having two longitudinal edges, one longitudinal edge of one spiral wall of each pair being fast with one end wall, the other longitudinal edge of the latter spiral wall bearing frictionally along an opposite end wall, one longitudinal edge of the other spiral wall of the pair being fast with said opposite end wall and the other longitudinal edge of the latter spiral wall bearing frictionally along said one end wall, one spiral wall and end wall of each pair being stationary, and the other spiral wall and end wall of each pair being movable by said moving means; the moving means comprising a shaft pivoted for movement in a conical path, rotary means for driving the shaft in said conical path, and means coupling the shaft with the movable wall of each pair, the coupling means comprising a bearing into which one end of the shaft extends and on which the movable spiral walls are driven in circular paths of the same size; a first spring reacting against the bearing and pressing one of the movable spiral walls against the end wall on which it frictionally bears, and a second spring reacting against the movable end wall which is fast with said one of the movable spiral walls and pressing the other of the movable spiral walls against the end wall on which it frictionally bears.

22. A fluid pump or motor comprising a first pair of spiral walls substantially identical to each other, and a second pair of spiral walls substantially identical to each other, the walls of each pair being fitted together approximately 180.degree. out of phase between end walls perpendicular to the spiral walls, with two lines of contact between the spiral walls of each pair, means for moving one spiral wall of each pair relative to the other spiral wall of the same pair, while maintaining said phase relationship, to advance said lines of contact spirally outward, for the first pair, from a fluid inlet to a fluid outlet, and spirally inward, for the second pair, from a fluid inlet to a fluid outlet, the inlets being in parallel and the fluid outlets being in parallel, each spiral wall having two longitudinal edges, one longitudinal edge of one spiral wall of each pair being fast with one end wall, the other longitudinal edge of the latter spiral wall bearing frictionally along an opposite end wall, one longitudinal edge of the other spiral wall of the pair being fast with said opposite end wall and the other longitudinal edge of the latter spiral wall bearing frictionally along said one end wall, one spiral wall and end wall of each pair being stationary, and the other spiral wall and end wall of each pair being movable by said moving means, the moving means comprising a shaft pivoted for movement in a conical path, rotary means for driving the shaft in said conical path, and means coupling the shaft with the movable wall of each pair, the rotary means for driving the shaft comprising a rotary drive member having an outer edge and a guideway extending towards said outer edge and engaging the shaft, the shaft having a center line intersected by a radius of the rotary drive member, and the guideway being at an angle to said radius whereby a dynamic force on the shaft normal to said radius has a component along the guideway urging the shaft to move in a direction along the guideway to press together the spiral walls of each pair at their lines of contact.

23. A fluid pump or motor comprising a pair of substantially identical spiral walls fitted together out of phase between end walls perpendicular to the spiral walls, with two lines of contact between the spiral walls, means for moving one spiral wall relative to the other, while maintaining said out of phase relationship, to advance the said lines of contact spirally from a fluid inlet to a fluid outlet, one of the end walls having an outer surface subjected to the pressure at the fluid outlet whereby it is fluid pressed towards the other end wall, each spiral wall having two longitudinal edges, one longitudinal edge of each spiral wall being fast with one end wall, the other longitudinal edge bearing frictionally along the other end wall, one spiral wall and end wall being stationary and the other spiral wall and end wall being movable by said moving means, the stationary wall being a wall of a chamber surrounding the movable end wall and the spiral walls, the movable end wall having a peripheral portion that sealingly divides the chamber into two compartments at opposite sides of the movable end wall, the advance of said lines of contact delivering fluid spirally inward in one of said compartments from the inlet to the outlet, the movable end wall having a port through which outlet fluid can flow to the other of said compartments where it urges the movable end wall towards the stationary wall.

24. A fluid pump or motor comprising a pair of substantially identical spiral walls fitted together approximately 180.degree. out of phase between end walls perpendicular to the spiral walls, with two lines of contact between the spiral walls, means for moving one spiral wall relative to the other, while maintaining said phase relationship, to advance the said lines of contact spirally from a fluid inlet to a fluid outlet, one of the end walls having an outer surface subjected to the pressure at the fluid outlet whereby it is fluid pressed towards the other end wall, each spiral wall having two longitudinal edges, one longitudinal edge of each spiral wall being fast with one end wall, the other longitudinal edge bearing frictionally along the other end wall, one spiral wall and end wall being stationary and the other spiral wall and end wall being movable by said moving means, said moving means comprise a shaft pivoted for movement in a conical path, means coupling the shaft with the movable spiral wall, a rotary drive member for driving the shaft in said conical path, the rotary drive member having an outer edge and a guideway extending towards said outer edge and engaging the shaft, the shaft having a center line intersected by a radius of the rotary drive member, and the guideway being at an angle to said radius whereby a dynamic force on the shaft normal to said radius has a component along the guideway urging the shaft to move in a direction along the guideway to press together the spiral walls at their lines of contact.

25. A fluid pump or motor comprising a first pair of spiral walls substantially identical to each other, and a second pair of spiral walls substantially identical to each other, the walls of each pair being fitted together approximately 180.degree. out of phase between end walls perpendicular to the spiral walls, with two lines of contact between the spiral walls of each pair, means for moving one spiral wall of each pair relative to the other spiral wall of the same pair, while maintaining said phase relationship, to advance said lines of contact spirally outward, for the first pair, from a fluid inlet to a fluid outlet, and spirally inward, for the second pair, from a fluid inlet to a fluid outlet, the inlets being in parallel and the fluid outlets being in parallel, the moving means comprising a shaft pivoted for movement in a conical path, rotary means for driving the shaft in said conical path, and means coupling the shaft with a movable wall of each pair, the rotary means for driving the shaft comprising a rotary drive member having an outer edge and a guideway extending towards said outer edge and engaging the shaft, the shaft having a center line intersected by a radius of the rotary drive member, and the guideway being at an angle to said radius whereby a dynamic force on the shaft normal to said radius has a component along the guideway urging the shaft to move in a direction along the guideway to press together the spiral walls of each pair at their lines of contact.