Rotating piston machine

The invention pertains to a rotary piston machine in which a rotor rotates in an enclosure and radially movable slides in the rotor form chambers of varying volume between the enclosure and the rotor, wherein an even number of slides is provided and mutually opposing slides are joined together into a rigid unit. The invention is characterized in that the rotor is arranged eccentrically in the enclosure, in that, in polar coordinates with the center in the rotor shaft, the inside wall of the enclosure (32) satisfies the following equation: EQU r.sub.(j) ={a>b>/[a> cos>(1(j+D/2))+b>> sin >>(1(j+D/2))]}.sup.1/2 where: b is the shortest distance between the rotor shaft and the enclosure wall in the south pole (S), a is given by the formula EQU a.sub.(d,b) ={[3(d/2).sup.4 -2b>(d/2)>]/[2(d/2)>-b>]}.sup.1/2 where: d is the length of slides and 1 is given by the formula EQU 1=2/D arccos ({[a>-(a.sup.4 +b.sup.4 -a>b>).sup.1/2 ]/(a>>-b>)}.sup.1/2).

BACKGROUND OF THE INVENTION
 The invention pertains to a rotary piston machine in which a rotor rotates
 in an enclosure and radially movable slides in the rotor form chambers of
 varying volume between the enclosure and the rotor, wherein an even number
 of slides are provided and mutually opposing slides are joined together
 into a rigid unit.
 Such a rotary piston machine is known from GB 430 715 B. Here the enclosure
 has the form of a Reuleaux triangle and the rotor is arranged centrally in
 the triangle. The advantage of such an arrangement over and above the use
 of one-sided spring-loaded slides is that in the rotation of the rotor,
 the enclosure wall need overcome only the inertial mass of the slide to
 move it back and forth while the centrifugal acceleration is at least
 essentially cancelled by the joining of the diametrically opposing slides,
 and spring forces that must always be provided for individual slides in
 order to press them against the wall in the first place can be completely
 eliminated.
 Thus, a rotary piston machine of the type mentioned initially is subjected
 to considerably reduced wear in comparison to rotary piston machines with
 individually movable slides.
 As more distant prior art pertaining to these other rotary piston machines
 that one can refer to, for instance, to DD-33 914 A in which the enclosure
 has a circular cross section, and the rotor arranged eccentrically in the
 enclosure likewise has an essentially circular cross section but with
 recesses bounded in cross section by a circular arc being cut out of the
 rotor in order to increase the size of the chambers formed. The (four)
 slides are each pressed outward from the rotor by springs against the
 enclosure wall, which, together with the centrifugal acceleration, leads
 to large contact pressures and high wear.
 Despite its advantages over and above DD-A, it is disadvantageous in the
 rotary piston machine known from GB-B in that, because of the compulsorily
 prescribed shape of a Reuleaux triangle, the formation of three enclosure
 pockets is inevitable during rotation, each pocket forming by a slide an
 initially expanding and then again shrinking chamber between the slides.
 In internal combustion engines, for instance, this necessarily leads to
 the formation of 6-stroke systems with intervening cooling sections.
 Another disadvantage caused by this is that each slide is pushed radially
 back and forth three times during a rotation which in turn in the course
 of a rotation leads to relatively high acceleration peaks.
 SUMMARY OF THE INVENTION
 The invention intends to create a remedy for this, and to specify a rotary
 piston machine of the type defined initially in which each slide is pushed
 back and forth only once in a [single] rotation of the rotor.
 This is achieved, according to the invention, in that the rotor is arranged
 eccentrically in the enclosure, in that the enclosure is symmetrical with
 respect to the connection line between the shaft of the rotor and the
 point of the enclosure closest to this axis, the south pole and in that,
 based on an XY coordinate system placed through the axis of rotation of
 the rotor and running orthogonally to and in the direction of the axis of
 symmetry, and with polar coordinates (r, j) with their center in the rotor
 shaft and the angle j=0 lying in the direction of the positive X-axis, the
 inside wall of the enclosure satisfies the following equation:
EQU r.sub.(j) ={a&gt;&gt;b&gt;&gt;/[a&gt;&gt; cos &gt;&gt;(1(j+D/2))+b&gt;&gt; sin &gt;&gt;(1(j+D/2))]}.sup.1/2
 where:
 b is the shortest distance between the rotor shaft and the enclosure wall
 at the south pole,
 a is given by the formula
EQU a.sub.(d,b) ={[3(d/2).sup.4 -2b&gt;&gt;(d/2)&gt;&gt;]/[2(d/2)&gt;&gt;-b&gt;&gt;]}.sup.1/2
 where:
 d is the length of the chords of the inside enclosure wall through the axis
 of rotation of the rotor, thus, the radial extension of the slides, and 1
 is given by the formula
EQU 1=2/D arccos ({[a&gt;&gt;-(a.sup.4 +b.sup.4 -a&gt;&gt;b&gt;&gt;).sup.1/2
 ]/(a&gt;&gt;-b&gt;&gt;)}.sup.1/2)
 Thus, the shape of the inside enclosure wall is completely determined by
 the choice of b and d; that is, the shortest distance between rotor shaft
 and inside enclosure wall, on the one hand, and the radial extension of
 the slides, on the other, since due to the requirement of symmetry with
 respect to the Y-axis, the curve need only be fixed in one quadrant and it
 will be fixed in the other quadrant; the others [sic; other parameters]
 result immediately.
 Added to the above are the boundary conditions: the horizontal profile
 (parallel to the X-axis) at the south pole (that at the north pole will
 result automatically), the position of the inside enclosure wall at the
 intersection with the X axis in a spacing d, the requirement for
 continuous differentiation two times in order to design the
 rotation-displacement motion of the slides without any jumps, monotonic
 increase of r.sub.(j) in the fourth quadrant and always non-negative
 curvature, whereby the curve is fixed.
 Configurations of the invention pertain to the formation of the slides and
 their guidance in the rotor or along the enclosure.

DETAIL DESCRIPTION OF PREFERRED EMBODIMENTS
 FIGS. 1--3 show various constructions of enclosure shapes that can be
 employed in keeping with the invention as functions of parameters a and b.
 The coordinate systems used, the south pole S, and the distances b and d
 are also entered with b set to 1 in each case since the shape of the curve
 depends only on the ratio a/b, and thus also, based on the relationship
 above, on a/d.
 As is immediately evident from FIGS. 1-3, according to the invention
 enclosure shapes in the range of a/b [from] 1/4 [to] 2 are certainly
 technically practicable while, for values of a/b that are considerably
 higher, strong accelerations of the slides appear when the latter are
 situated in an equatorial position (parallel to the X-axis). Additionally,
 contact forces from the enclosure wall that press strongly and are
 directed out of the slide plane are also active in this position, and thus
 do not qualify such shapes for technical utilization.
 Usable ratios a/b lie between 1.0 and 2.5, preferably between 1.25 and 2.0,
 a and b having the significance stated above.
 Even for the ratios shown in FIGS. 1 and 2, and obviously also for those in
 which a &lt;1.5 or only slightly more than 2, a rotary piston machine is
 created which does not exhibit the disadvantages of previously known
 machines and, in particular, has favorable dynamic conditions for the
 motion of the slides in the radial direction of the rotor and also along
 the inside enclosure wall.
 FIG. 4 shows a section perpendicular to the axis of rotation of a turbine
 or ventilator according to the invention. Slides 1 move in the rotor 19
 guided in oil, as is explained in detail below. In the enclosure wall 32,
 drawn in only schematically in all illustrations, the suction opening 17
 and the pressure opening 23 are shown schematically by hatching.
 Use as a pump for generating a vacuum and for pumping fluids as well as for
 compressing can be accomplished in an analogous but reversed manner.
 FIG. 5 shows a section of a rotary piston internal combustion engine
 perpendicular to the axis of rotation according to the invention. A
 suction opening 17 of a compressor stage is schematically drawn in the
 enclosure wall 32, as well as an overflow channel 18 which leads from the
 compression side of the compressor stage to the suction side of the engine
 stage. There is an injection nozzle 20 shown in the area of the expansion
 chamber.
 The slides 1 of the compressor stage are again guided in oil in the rotor
 19; for thermal reasons, this is not possible for the slides 21 of the
 rotor 22 in the combustion chamber.
 The spent combustion gases leave the rotary piston internal combustion
 engine at the exhaust opening 23. FIG. 6 shows a section through the
 parallel rotor shafts 30, 33 of the two rotors 19, 22 of FIG. 5. In
 particular, the rounded corner shaping of the enclosure chambers can be
 discerned from this figure. The bearings 29 for the rotors 19, 22 and the
 gears 31 that ensure the powering of the compressor rotor 19 are shown.
 FIG. 7 shows a section perpendicular to the rotor shafts of a rotary piston
 jet engine. A precompressor outlet opening issues into an expansion
 chamber 27 that ends in the exit nozzle 28; also evident are the
 schematically drawn suction opening 17 and the overflow channel 18 that
 leads from the precompressor stage into the expansion stage. The slides 1
 guided in the precompressor rotor 19 are preferably again guided in oil,
 while this is not possible for the slides in the rotor 22, as they are
 highly stressed thermally by the combustion process.
 According to the invention, FIG. 8 shows a preferred slide 1, in section,
 in side view and in plan view, in which grooves 3 are visible into which
 spring yokes, one of which is represented in FIG. 9, can be inserted. Oil
 channels 2 are provided in the slider, which, due to the centrifugal
 acceleration, transport oil that is supplied in the area of the rotational
 axis outward and there lubricate and cool the slide 1 or spring yoke
 during its rotation along the inside enclosure wall.
 FIG. 9 shows a spring yoke that can be inserted into the grooves 3 of a
 slide 1 and is provided with lubrication openings 5 from which the
 lubricating fluid can exit. The arrows indicate the direction of the
 (slight) elastic deformation caused by the centrifugal acceleration, by
 which deformation the seal on the inside enclosure wall is improved.
 The bridges 34 between the two ends of the slide 1 are offset in the
 individual slides of a rotor by at least the bridge width, so that the
 individual slides are arranged to be radially movable past one another.
 FIG. 10 shows a rotor for oil-lubricated slides 1 which is thus not able to
 withstand high thermal stresses since otherwise carbonization of the oil
 would occur. Other fluids besides oil can be employed for lubrication,
 both oil and the other fluids being usable for cooling. In the case of
 vacuum pumps, particularly because oil contamination can not be removed
 from a vacuum, the slide can be cooled and lubricated by fluids such as
 water.
 Such a rotor 19 preferably consists of rotor segments 7 which are held
 together with intermediate slot-like spaces by rotor sidewalls with
 mounting holes 11. The slides 1 slide in the spaces 12. Ellipsoidal rings
 13 (FIG. 11) are inserted into grooves 8. The grooves 9 accommodate
 segment gaskets 15 (FIG. 13); oil supply for the slides 1 or the spring
 yokes 4 is accomplished through an inlet opening 10 in the rotor shaft.
 In FIG. 11, an ellipsoidal ring 13 is shown in a side and a plan view. The
 direction of pressure here is indicated by arrows. The ellipsoidal ring 13
 has an opening 16 for equalizing pressure and expansion. The ellipsoidal
 ring 13 serves to seal the slide 1 off with respect to the rotor; in the
 illustrated embodiment, two such ellipsoidal rings are provided on each
 side of the rotor for each of the slides 1, thus, four ellipsoidal rings
 per slide [are needed].
 A rotor segment in front and side view can be seen in FIG. 12; the grooves
 8 for the ellipsoidal rings 13 or the grooves 9 for the segment gasket 15
 (FIG. 13) can also be seen. The holes 14 of the rotator segments 7
 cooperate with the holes 11 in the lateral disc 6 and serve to assemble
 the lateral discs 6, 25 (FIG. 6).
 In FIG. 13, a segment gasket 15 is represented in front and side view. This
 segment gasket 15 seals off the rotor with respect to the lateral
 enclosure wall and is constructed to be self-contacting.
 FIG. 14 shows a rotor able to withstand high thermal stresses in an axial
 section in which a combustion chamber 26 is provided in each segment. An
 individual rotor segment is shown in front and side view in FIG. 15; FIG.
 16 shows an associated slide 21, which differs from slide 1 in its lack of
 an oil supply and thus of lubrication. Here too, the bridges 34 are
 arranged as for slide 1 (FIG. 8).
 The mode of operation of the rotary piston machine, according to the
 invention, is the same as that for ordinary rotary piston machines; except
 for the dynamic improvements of the slide movement and of the spatial
 configuration of the slides which thereby becomes possible, no change from
 prior art regarding operation has taken place.