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1. (WO1991005940) PUMP OR MOTOR
Note: Text based on automatic Optical Character Recognition processes. Please use the PDF version for legal matters


THIS invention relates to a positive displacement device in the form of a pump or motor.

The term "pump or motor" is intended to embrace motors such as internal combustion motors, hydraulic or pneumatic motors, pumps and compressors.

A positive displacement device according to the present invention comprises first and second members presenting opposing, undulating surfaces defined by alternating lobes and valleys which cooperate with one another to define variable volume chambers when the members move relative to one another in a first direction and reciprocate relative to one another in second direction transverse to the first direction.

Preferably, the device comprises two first members which present undulating surfaces that are spaced apart from and face one another and a single second member which is located between the undulating surfaces of the first members, the second member presenting undulating surfaces on opposite sides thereof which oppose the undulating surfaces of the first members so that variable volume chambers are defined by the lobes and valleys of the members on both sides of the second member.

The device may serve as a pump or motor. In the case of a motor, means are provided for supplying pressurised fluid to the chambers to cause them to expand with corresponding movement of the second member relative to the first members in the first direction and reciprocation of the second member relative to the first members in the second direction.

SUBSTITUTE SHEET In one form of the invention, the first members may be stationary stators and the second member may be shaft-mounted rotor which is arranged to rotate between the stators on the shaft and to reciprocate in the axial direction of the shaft relative to the stators.

The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings in which:

Figure 1 shows a diagrammatic, sectional side view of a device according to the invention;

Figure 2 shows a perspective view of the rotor used in the device of Figure

Figure 3(a) to 3(c)
shows a partial, cross-sectional developed view of the rotor and stators of the Figure 1 device at various stages during operation;

Figure 4 shows a cross-sectional view at the line 4-4 in Figure 2; and

Figure 5 shows a view similar to Figure 3(c) but with the device used in another application.

The invention will now be described in its application as an internal combustion engine.

In Figure 1, the numeral 10 indicates the output shaft of an internal "combustion engine. The shaft has splines 12 which support a rotor 14 in a rotationally fast manner and which permit axial movement of the rotor 14 on the shaft. As illustrated by Figure 2, the rotor has annular surfaces 16 on opposite sides thereof

SUBSTITUTE SHEET which are of undulating profile and which are constituted by alternating lobes and valleys 18 and 20 respectively. It will be noted that there are four lobes and four valleys on each surface 16 and that the lobes on one surface 16 are opposite the valleys on the opposite surfaces 16, i.e. the lobes are 45" out of phase on the two surfaces 16.

The rotor 14 is located between the two stators 22 which have inwardly directed, annular surfaces 23 that are likewise constituted by alternating lobes and valleys 24 and 26 respectively. Each surface 23 of the stators has four such lobes and valleys.

The rotor surfaces 16 are provided with spaced seal elements 26 which extend across the faces of the lobes 18. The seal elements are biased outwardly along a line of action by means of springs 28 so as to form good seals with the surfaces 23 of the stators at the appropriate stages during movement of the rotor relative to the stators. It will be appreciated that the angle of this line of action relative to the opposing face will vary throughout the cycle. However, this angle will not vary to the extent found in the tip seal of a Wankel engine.

The stators themselves are mounted in a stationary manner between end members 30 (Figure 4) forming part of the engine housing and inner and outer side seals 32 are provided at the radially inner and outer edges of the rotor surfaces 16 to seal against the housing members 30.

Referring now to Figures 3(a) to 3(c), there is shown in each case a partially developed view illustrating the interaction of the rotor and stators. The stator lobes have inlets 34 and exhaust ports 36 (Figure 3(c)) which open into the space between them and spark generators, for example in the form of spark plugs 38, which are arranged to generate sparks, under the control of an external timing apparatus, in the space between the stators.

SUBSTITUTE SHEET The position of the shaft 10 is indicated in Figures 3(a) to 3(c) in broken outline and the direction of rotary movement of the rotor relative to the stator is indicated by the arrow 40. Figures 3(a) and 3(b) show successive positions of the rotor as it moves in the direction 40. When the rotor is in the position of Figure 3(a), the chamber 42 is at maximum volume. When the rotor moves slightly in the direction of the arrow 40, the chamber 42 undergoes compression as indicated in Figure 3(b). At the same time, the chamber 44 starts expanding from the initial Figure 3(a) position of maximum compression. At a later stage in the movement of the rotor, the chamber 42 will be at maximum compression and the chamber 44 at maximum volume.

As a chamber starts expanding, a fuel/air mixture supplied to the relevant inlet 34 (Figure 3(c)) is drawn into the chamber. As the rotor moves past a position of maximum volume, the chamber volume decreases and the fuel/air mixture is compressed. At the appropriate stage of compression, the relevant spark generator is energised to generate a spark which ignites the fuel/air mixture. The expanding gases drive the rotor further in the direction of the arrow 40. Shortly thereafter, the relevant rotor lobe uncovers the relevant exhaust port 36 and the gases are all exhausted. Thereafter, the exhaust port 36 is closed and the inlet port 34 is uncovered again as the rotor moves further in the direction of the arrow 40, and the process repeats itself.

It will be appreciated that this process is carried out sequentially in each of the chambers, on both sides of the rotor, so that power strokes are applied to the rotor at short time intervals, the result being a relatively even driving force on the rotor. In the illustrated embodiment, with four lobes on each of the stators and on the rotor, each spark plug will ignite four times for each revolution of ttie shaft 10. There will thus be sixteen power' strokes per 360' of shaft rotation for the illustrated embodiment which has four spark plugs 38. The spark plugs ignite alternately in pairs for every 45" of shaft rotation. By way of comparison, a four-

SUBSTITUTE SHEET stroke piston-and-cylinder internal combustion engine having four cylinders only has two power strokes per revolution of the crankshaft, i.e. one power stroke per 180° of crankshaft revolution. A four-stroke, six cylinder engine will have three power strokes per shaft revolution, i.e. one power stroke per 120' of shaft revolution. Accordingly, it is believed that the rotary drive which is obtained using the device of the invention will lead to a smoother power output.

Furthermore, the surfaces 16 and 23 of the rotor and stators may be positioned a substantial distance from the axis of the shaft 10 and certainly further from the axis than the cranks of a conventional crankshaft are from the axis of the crankshaft. Thus the point of application of the driving force and the resulting turning moment and torque output can be greater per unit driving force than with a conventional piston-and-cylinder and crankshaft drive.

It will be appreciated that the rotary motion of the rotor 14 is accompanied by reciprocating movement thereof in the direction of the shaft axis, such movement being taken up by the splines on the shaft 10.

It will naturally be most important to achieve adequate sealing of the chambers 42, 44. The drawings show the undulating profiles of the rotor and stators to be virtually identical, but in practice, these profiles will be somewhat different to permit efficient sealing and to allow the lobes of the rotor to pass the lobes the stators without frictional resistance. The side seals 32 may be floating seals which are forced outwardly against the housing members 30 when the relevant chambers 42, 44 are under compression by differential pressures, i.e in Figure 4, the pressure of compressed fluid acting on the surfaces 48 of the seals 32 will urge them outwardly against the members 30. Alternatively, the seals 32 could be spring-loaded to act outwardly on the surfaces of the members 30.

SUBSTITUTE SHEET The above description of a device of the invention in use as an internal combustion engine is in no way limiting on the scope of the invention. In the context of an internal combustion engine, the rotor and stators could, for instance, have a greater number of lobes so that more power strokes are achieved per revolution of the shaft. The undulating profiles provided by the lobes and valleys could be selected for a particular application to increase or decrease the capacity of the variable volume chambers and thereby vary the power output of the engine.

It will also be appreciated that the rotor could be a stationary member and the stators could be the rotating members, in which case the stators would be carried by the shaft. Instead of rotary motion, the principles of the invention can be applied to straight line or other motion. In the case of straight line motion, the "rotor" and "stators" could merely be straight lengths with appropriate undulating surfaces mating with one another and with suitable housing members sealing the edges of the members.

As mentioned previously, the device of the invention could serve both as an engine as described above or as a pump or compressor. In the case of a pump or compressor, the fluid to be pumped or compressed would be drawn into the various chambers during the expansion of those chambers and then exhausted under pressure as the chamber volume decreases.

It is envisaged that the device could operate as a diesel engine, with the chambers serving to compress the diesel mixture sufficiently for spontaneous ignition thereof. Furthermore, the device of the invention could be used as an hydraulic motor.

Reference is made to Figure 5. which shows a similar diagram to the One shown in Figure 3(c). Inlet and outlet ports 'are arranged in a similar fashion to the ports used in the application of the device as an internal combustion engine. The present application of the device as an hydraulic motor will be described with

SUBSTITUTE SHEET reference to inlet ports shown at 50 and 52 in the diagram, and outlet ports 54 and 56.

Referring firstly to inlet port 50 and outlet port 54, pressurised fluid fed in at 50 serves to drive the rotor in the direction of rotation indicated by arrow A, which opens up a chamber between surfaces 58 and 60. At the same time, the rotor is being displaced in the axial direction of the shaft 26 towards outlet port 54. Consequently, chamber 62 is compressed to exhaust its contents of fluid out through outlet port 54. The inlet port 50 and outlet port 54 work as a pair. As pressurised fluid is fed in through port 50, so exhaust fluid exits through port 54. The process is exactly the same for ports 52 and 56, although of course the admission of pressurised fluid through port 52 will occur 45' earlier or later in the overall cycle of the device than the admission of pressurised fluid through port 50.