Rotary expansible chamber devices – Interengaging rotating members – Helical or herringbone
Reexamination Certificate
1999-07-28
2001-01-23
Vrablik, John J. (Department: 3748)
Rotary expansible chamber devices
Interengaging rotating members
Helical or herringbone
Reexamination Certificate
active
06176695
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a rotary device.
BACKGROUND OF THE INVENTION
In WO-A-
91/00-747
, there is disclosed a rotary device having interacting rotors which have a helical form in their axial direction.
In an internal combustion engine using such a rotary device, there are separate rotary compression and expansion sections.
In a fluid compressor, the rotor pairs serve to compress and deliver compressible fluids into receivers in which the receiver pressure is substantially greater than that of the fluid source. Power is supplied by an external prime mover in order to drive the rotor pair and thus to compress the fluid, raising its pressure from that of the supply source to that of the receiver. For efficient operation of a positive displacement compressor, it is desirable to raise the pressure of the fluid charge to a level equal to that of the receiver before beginning to deliver the charge into the receiver. In the rotor system disclosed in WO-A-91/06747, there is a port in a side wall. Opening of the port is effected when the leading edge of a transfer passage in the rotor passes over the approach side of the port in the side wall. The timing of the opening of the port for the start of delivery of the charge is therefore determined by the location of the passage at a predetermined position in the recess of one rotor and is therefore incapable of adjustment during operation of the compressor. It is desirable to have means to adjust the initial charge volume so as to ensure equalisation of the charge pressure with that of the receiver at the instant at which the port begins to open. This is particularly important when the compressor does not operate with a reed valve and when the pressures of the fluid supply source and/or the receiver are not constant.
In a rotary internal combustion engine having rotor systems as disclosed in WO-A-91/06747, the rotors serve as positive and negative displacement systems, thereby effecting the volume changes which take place in the working fluid throughout the thermodynamic cycle of the engine. Most applications of internal combustion engines require power to be delivered over a range of shaft speeds and at varying torque loads. For internal combustion engines other than compression-ignition types, variation of the output power and engine speed is effected by varying the mass of working fluid used during the cycle. It is therefore desirable to provide means for varying the volume, and therefore the mass, of working fluid entrapped at the start of the cycle.
In both rotary devices of this type, i.e. in both compressor and internal combustion engine applications, it is desirable to be able to vary the maximum volume or mass of the charge during operation of the rotors.
SUMMARY OF THE INVENTION
According to the present invention, there is provided a rotary device, the device comprising: a first rotor rotatable about a first axis and having at its periphery a recess bounded by a curved surface; a second rotor counter-rotatable to said first rotor about a second axis, parallel to said first axis, and having a radial lobe bounded by a curved surface; the first and second rotors being coupled for rotation and being intermeshed; a housing in which the rotors are enclosed, the housing having a first arcuate recess which is coaxial with the first rotor, an edge of the recess of the first rotor forming a sliding seal with the first arcuate recess during a portion of the rotation of the first rotor, the housing having a second arcuate recess which is coaxial with the second rotor, the lobe of the second rotor forming a sliding seal with the second arcuate recess during a portion of the rotation of the first rotor, such that, for a portion of the rotation of the rotors, there is defined between the first and second rotors and the arcuate recesses of the housing a transient chamber of volume which progressively decreases on rotation of the rotors; and, varying means for varying the maximum volume of the transient chamber.
Thus, the maximum volume of the transient chamber can be varied, thereby allowing the pressure and/or volume of a fluid entrapped in the transient chamber to be varied prior to transfer of said fluid out of the transient chamber. The initial charge volume can be adjusted so as to ensure equalisation of the charge pressure with that of the receiver at the instant at which the port begins to open; this is particularly useful when the rotary device is used in a compressor. The volume, and therefore the mass, of working fluid entrapped at the start of the cycle can be varied; this is particularly useful when the rotary device is used in an internal combustion engine.
The varying means may comprise the housing arcuate recesses being formed in a section of the housing which is movable relative to the housing and rotors thereby to vary the maximum volume of the transient chamber.
Where provided, the movable section may conveniently be mounted on a linear bearing for reciprocating movement parallel to the axes of both rotors.
The rotary device preferably has side walls which define with the rotors the transient chamber, the side walls having recesses into which the movable section is movable.
Control means may be provided for controlling the varying means.
Where the rotary device is a compressor, pressure measuring means may be provided for measuring the pressure of a working fluid in the transient chamber and the pressure in a receiver to be supplied with compressed fluid from the transient chamber. Control means can be provided for controlling the varying means so that the pressure in the transient chamber is substantially equal to the pressure in a said receiver immediately prior to transfer of the working fluid from the transient chamber to a said receiver.
A reed valve may be provided in a delivery port between the transient chamber and a said receiver.
Control means may be provided for monitoring the difference between the pressure of a working fluid in the receiver and the maximum allowable pressure in the receiver and for controlling the varying means to adjust the delivery flow rate of working fluid from the transient chamber to a said receiver in accordance with usage of the compressed fluid.
Where the rotary device forms a portion of an internal combustion engine, operator control means may be provided for operator control of the position of the varying means.
Said rotor recess, rotor lobe, and housing arcuate recesses preferably extend helically in the axial direction.
The curved surfaces may be contoured such that during passage of said rotor lobe through said rotor recess, said recess surface is continuously swept, by both a tip of said lobe and a movable location on said lobe which location progresses along said lobe surface, to define said transient chamber.
The speed of rotation of the first, recessed, rotor is preferably lower than the speed of rotation of the second, lobed, rotor by a ratio, less than 1:1, of whole numbers.
Both rotors may have respectively equiangularly spaced recesses and lobes in the same ratio of recesses to lobes as the speed ratio. In a particular example, the first rotor has three equiangularly disposed recesses, and the second rotor has two diametrically opposed lobes, and the ratio of their speeds of rotation is 2:3.
REFERENCES:
patent: 2369539 (1945-02-01), Delamere
patent: 3045447 (1962-07-01), Wagenius
patent: 4579513 (1986-04-01), Zimmern et al.
patent: 4667646 (1987-05-01), Shaw
patent: 5090392 (1992-02-01), Nakano et al.
patent: 1118800 (1961-12-01), None
patent: 162157 (1985-11-01), None
patent: 484885 (1992-05-01), None
patent: 2098662 (1982-11-01), None
patent: 91/06747 (1991-05-01), None
Pillsbury Madison & Sutro Intellectual Property Group
Rotary Power Couple Engines Limited
Vrablik John J.
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