Radial seal of a rotary piston engine

A radial seal for a rotary piston engine having a trochoidal-shaped casing inner surfacing and a multi-corner piston with which sealing strips are arranged in radial grooves in the corners of the piston. The sealing strips engage under pressure of the operating chambers against the casing inner peripheral surfacing and respectively against the lower-pressure-side groove wall. The sealing strips have perforations or openings between the sealing surfaces coming into engagement along the groove walls. Filler pieces are inserted or installed with nominal clearance in the perforations or perforations in the sealing strip. These filler pieces are narrower in peripheral direction in the dimensioning or measurement thereof compared with the sealing strip. A spring holds the filler pieces in continuous engagement against an upper part of the sealing strip. Groove clearance of the sealing strip amounts to a value in a range of 0.04 to 0.08 mm and the groove clearance of the filler pieces amounts to a value in a range of 0.1 to 0.2 mm.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a radial seal of a rotary piston engine 
with a trochoidal-shaped mantel raceway or casing inner peripheral 
surfacing and a multi-corner piston means. Sealing strips are arranged in 
radial grooves in the corners of the piston means; the sealing strips 
under pressure of the working or operating chambers of the rotary piston 
engine engage against the mantel raceway or casing inner peripheral 
surfacing and respectively also engage against an under-pressure-side 
groove wall. The sealing strips have perforations or breakthroughs in the 
sealing surfaces thereof coming into engagement along the groove walls. 
2. Description of the Prior Art 
Such sealing strips are exposed and subjected to a tipping, tilting or 
pitching moment under the working or operating pressure effective upon a 
part or portion of the sealing strips projecting beyond the groove edges 
and under the effect or result of rolling friction, rubbing or abrasion of 
the crest, arch, dome or apex thereof along the mantel raceway or casing 
inner peripheral surfacing along which the sealing strips move; such 
tipping, tilting or pitching moment can lead to jamming of the sealing 
strip in the groove and with that can lead to hindrance or restraint of 
movement, to hammering, to leakiness and to undue wear on the sealing 
strip and mantel raceway or casing inner peripheral surfacing. 
Consequently an endeavor or effect is made to keep and maintain the groove 
clearance of the sealing strip as small as possible in order to prevent 
any tipping, tilting or pitching of the seal strip. With a groove 
clearance that is too small or nominal however, the groove gap resulting 
on the pressure side along the low-pressure-side groove wall during 
engagement of the sealing strip is too narrow in order to permit and allow 
the working or operating pressure in the groove base or bottom to reach or 
come below the sealing strip in a timely manner. The sealing strip then 
cannot seal-off with full pressure of engagement with respect to the 
mantel raceway or casing inner peripheral surfacing. 
In order to eliminate or remove this disadvantage, there was proposed in 
German Pat. No. 12 23 614 Paschke dated Mar. 9, 1967 (corresponding to 
U.S. Pat. No. 3,185,387--Paschke dated May 25, 1965) to reduce the cross 
section of the radially inner part of the sealing strip in peripheral 
direction with respect to the upper part coming into engagement against 
the groove walls in the region of the groove edges and additionally in the 
lower part to provide continuous perforations or breakthrough means in 
peripheral direction, whereby the space for the flowing-in of the pressure 
gas is adequately enlarged. The arrangement of such large spaces or 
chambers however results in the disadvantage that the filling-up thereof 
with pressure gas requires a time delay, which does not permit and allow 
an intermediate seal effectiveness, which most of all is important at 
higher rotary speeds. The aforementioned German Patent consequently 
already proposes to close the recess spaces or chambers between the 
sealing strip and the groove with filler pieces (fairing) or corresponding 
configurations and construction of the groove base or bottom. This in 
itself is a contradiction to the teaching of this patent disclosure and 
this proposal is not adequately explained either in the description or in 
the drawings. The proposed recesses, notches, cutouts or openings 
additionally have the disadvantage that the under-pressure-side sealing 
surface is too small between the sealing strip and the groove wall. 
In the U.S. Pat. No. 4,403,930--Kodama dated Sept. 13, 1983 for a 
Multi-Piece Apex Seal Structure for a Rotary Piston Engine there is 
proposed a sealing strip which is divided in a plane located in peripheral 
or circumferential direction, with which the radially inner part is 
narrower with respect to the radially outer part adjoining or engaging 
against the mantel raceway or casing inner peripheral surfacing and is 
shiftable in circumferential or peripheral direction. 
The lower part of the seal length strip is shifted toward the 
under-pressure-side groove wall via the operating pressure, whereby an 
expanded or widened access or entry pass into the groove base is obtained 
for the pressure gas, without receiving too wide and only belated fillable 
spaces or chambers. Additionally, there results a greater elasticity and 
close contact or adhesion of the sealing strip with respect to 
temperature-conditioned or temperature-limited unevenness and distortion 
of the mantel raceway or casing inner peripheral surfacing. 
The advantage of the narrowing or constriction of the groove made possible 
therewith however is again nullified by the considerable shortening of the 
sealing strip in radial direction, since only the radially outer part of 
the sealing strip can be considered, because the possible canting or 
tipping angle is enlarged with radial shortening of the sealing strip with 
a given groove width. 
An object of the present invention accordingly is to provide a sealing 
strip, with which an adequate or sufficiently quick access or entry of the 
pressure gas underneath the sealing strip is made possible; this occurs 
with the smallest possible dead-space formation being encountered 
therewith; furthermore a wide-surface engagement of the 
under-pressure-side thereof against the groove wall is attained therewith 
also provided are higher elasticity and close contact and snug adherence 
as to the unevenness and distortions of the mantel runway or casing inner 
peripheral surfacing. This object is met and fulfilled with the features 
of the present invention.

DESCRIPTION OF PREFERRED EMBODIMENTS 
FIG. 1 shows a housing mantel or casing 1, having a housing sidewall 2 and 
also having a mantel raceway or casing inner peripheral surfacing 3. A 
triangular piston 4 in an illustrated corner 5 thereof has a radial groove 
6 in which a sealing strip 7 is arranged radially movable and shiftable in 
peripheral or circumferential direction; and the sealing strip 7 is 
pressed against the mantel raceway or casing inner surfacing 3 by a spring 
8 as well as by pressure gas from the preceding operating chamber 9. In 
the sealing strip 7 there is provided a circumferentialy continuous 
perforation, passage or open breakthrough 10, which as apparent in a 
lateral plan view is limited in axial direction by edge webs or 
crosspieces 11 and 12 as well as on a radially inner side thereof by an 
edge strip 14 having an opening or perforation 13 broken therethrough. In 
the perforation 10 there is a filler piece 15 of lightest possible 
material, for example of aluminum or temperature resistant synthetic 
material installed with a small or nominal clearance. A round or annular 
spring 16 engages in the perforation 13 of the edge strip 14. This annular 
or elongated spring 16 is supported upon the other side against the spring 
8 and can be connected therewith. The spring 16 presses the filler piece 
15 with a radially outer edge thereof against an upper part 17 of the 
sealing strip 7. The filler piece 15 is narrower in measurement or 
dimension in peripheral direction than the sealing strip 7, which is 
equally thick in all of the parts 17, 11, 12 and 14 thereof. The filler 
piece 15 as a consequence of clearance thereof is movable to a certain or 
predetermined extent in radial direction. The filler piece 15 however is 
pressed by the annular spring 16 and the gas pressure against the upper 
part 17 of the sealing strip 7. Consequently, the sealing strip 7 and 
filler piece 15, with respect to the sealing effect thereof, actually 
represent a unitary sealing strip acting in common. 
During pressure impingement or engagement from one side, for example as 
shown in FIG. 4, and taken from the preceding operating chamber 9, there 
is noted that the lighter filler piece 15 is pressed against the 
lower-pressure-sidewall of the groove 6 and with that there is attained a 
valve effect. Thereupon the sealing strip 7 having a greater mass is 
pushed subsequently or follows against this groove wall, whereby via the 
retraction of the filler piece 15 with respect to the sealing strip 7 
there is formed a sufficiently and adequately large pass or passage 18 for 
pressure gas in the groove base or bottom and under the sealing strip, 
although this pass or passage 18 contains no unnecessary dead spaces or 
chambers. The width of the groove 6 consequently can be kept and 
maintained so small that a binding or jamming tipping, canting or tilting 
of the sealing strip 7 is avoided, whereby the filler piece 15 as a 
consequence of its tight engagement against the upper part 17 of the 
sealing strip 7 cooperates as a lever arm against the tipping, tilting or 
canting of the sealing strip 7. As a consequence of the continuous radial 
longitudinal expansion of the sealing strip there is noted that tipping or 
tilting thereof is readily restricted and limited. 
For purposes of illustration and as an example there can be set forth as 
advantageous dimensions and measurements the following values: 
groove clearance of the sealing strip 7 for example in a range of 0.04 to 
0.08 mm; 
groove clearance of the filler piece 15 for example in a range of 0.1 to 
0.2 mm. 
The filler piece 15 accordingly can be narrower by a range of 0.2 to 0.3 mm 
than the thickness of the sealing strip 7. 
As shown in FIGS. 2 and 3 the spring 16 pressing the filler piece 15 
radially outwardly can be arranged as a spring 19 in an axial groove 20 in 
the underside of the filler piece 15, so that the perforation, passage or 
breakthrough 13 of the lower edge strip 14 of the sealing strip 7 is 
unnecessary. 
As shown in FIG. 5 the filler piece 15 can be rounded off in oppositely 
located curved configurations along a radially upper side and a radially 
inner side thereof radially outwardly and radially inwardly of a middle or 
center axis 21; these curved configurations are to prevent and preclude a 
jamming during a temporary tipping in an engaging movement thereof in the 
perforation or breakthrough 10. 
The sealing strips described in the foregoing sample embodiments in spite 
of having a radial width equal with respect to the solid or unitary 
sealing strips can have an increase or elevated elasticity and close 
contact, snug adherence capability. 
In summary, the present invention provides a radial seal for a rotary 
piston engine with a trochoidal-shaped mantel raceway or casing inner 
peripheral surfacing as well as a multi-corner piston means, with which 
sealing strips are arranged in radial grooves in corners of the piston 
means. These sealing strips under pressure of the operating chambers 
engage against the mantel raceway or casing inner peripheral surfacing and 
respectively against the lower-pressure-side groove wall; and the sealing 
strips have perforations, passages or breakthroughs between the sealing 
surfaces coming into engagement against the groove walls. The radial seal 
is further characterized thereby that narrower filler pieces 15 are 
inserted or installed with nominal clearance in at least one perforation 
or breakthrough 10 in the sealing strip. The filler pieces 15 are narrower 
in the dimension or measurement thereof in peripheral direction when 
compared with the dimension or measurement of the sealing strip in 
peripheral direction. A spring 16, 19 holds the filler pieces 15 in 
continuous engagement against an upper part 17 of the sealing strip 7. The 
groove clearance of the sealing strip 7 amounts to a value in a range of 
0.04 to 0.08 mm and the groove clearance of the filler pieces 15 amounts 
to a value in a range of 0.1 to 0.2 mm. 
In FIG. 1 the radially inner edge strip 14 of the sealing strip 7 has 
perforations or breakthrough means 13, through which springs 16 engage 
pressing the filler pieces 15 against the upper part 17 of the sealing 
strip 7. 
In FIG. 2 the filler pieces 15 along a radially lower side thereof have a 
groove 20 extending in axial direction; a spring 19 is installed or 
inserted in this groove 20 and this spring 19 presses the filler pieces 15 
against the upper part 17 of the sealing strip 7. 
In FIG. 5 the filler pieces 15 are rounded-off about the center axis 21 
thereof along the radially outer and inner edges thereof. 
The present invention is, of course, in no way restricted to the specific 
disclosure of the specification and drawing, but also encompasses any 
modifications within the scope of the appended claims.