Compressor

An oscillating piston compressor characterized by a spherically contoured piston chamber in which a wedge-shaped disk-like piston is journaled for oscillating motion on an axle journaled in the housing and coinciding with the juncture of a pair of semi-circular sectors forming the piston. A cam formed on the side of the piston opposite the pressure side, is contacted either by a rotating eccentric cam, a crankarm, or a crankpin for imparting oscillating motion to the piston to effect compressing action. A flat circular valve plate, in which intake and exhaust valves are disposed, is fixed transversely in the housing for separating the piston compression chambers from intake and delivery chambers.

BACKGROUND OF THE INVENTION 
The invention concerns an oscillating piston compressor. Certain 
oscillating piston compressors have become known as "Dry-Running 
Compressors" comprising an impeller-like piston axially resting on a 
piston rod for oscillating back and forth thereon in a cylindrical piston 
housing. With this known oscillating piston compressor, the piston housing 
contains at least one radial intermediate wall in order to create a limit 
for a compression chamber. An isolating or sealing strip arrangement is 
not effectively feasible with this design, so that compressed air may 
escape from the compression chamber into the suction or intake chamber. 
This situation results in a poor degree of compressing efficiency and in 
uncontrolled temperature variations, especially increase. 
Another design of an oscillating piston compressor, more favorable with 
regard to the packing strip arrangement, is characterized by a spherical 
housing divided at the area of its largest diameter for the purpose of 
mounting the rotating piston. Due to such division of the housing, a 
cumbersome, two-part piston must be used. A unitary piston cannot be used 
in this last-mentioned type compressor, since it would have to travel over 
a junction seam. This could lead to rapid wear and possibly even to 
rupture of the sealing element. 
With the last-mentioned oscillating piston compressor, oscillation of the 
pistons is effected by a hobbing or camming action taking place over steep 
cam surfaces. This results in a one-sided compression chamber, which leads 
to unequal thermal stresses of the housing. 
In the case of the presently known oscillating piston compressors above 
described, the operation is complicated because of the housing design. An 
arrangement of the drive within the housing is not directly possible, so 
that an economic production and use is not possible without additional 
expenditure. For this reason, a further known oscillating piston 
compressor has been proposed in which the radial intermediate walls are 
eliminated, so that a piston having semi-circular sectors may be used 
advantageously with a spherically-shaped housing having a correspondingly 
spherically-shaped interior chamber, and in which housing the drive 
arrangement may be accommodated. 
To attain the aforementioned advantage, the further known oscillating 
piston compressor is characterized by the following features: 
(a) a blade-like disk, oscillating back and forth in the housing inner 
chamber on a bearing axle, whose oscillating movement is effected by means 
of a drive, forms the oscillating piston; 
(b) the blades of the oscillating piston making sealing contact with the 
inner spherical surface of the housing, form two compression chambers in 
cooperation with the internal surface of the housing inner chamber and the 
valve plate; 
(c) charging of the compression chambers takes place from the atmosphere by 
means of inlet valves or scavenging ports; 
(d) delivery of compressed air from compression chambers to the devices 
using the compressed air takes place via pressure valves; 
(e) the cylinder bearing surface is designed spherically and does not have 
juncture seams in the area of contact by oscillating movement of the 
piston which is complementarily designed to correspond to the spherical 
radius of the housing; 
(f) the bearing axle of the oscillating piston represents the geometric 
center point of the sphere diameter; 
(g) the compression chambers, limited by the intermediate wall, designed as 
a valve plate, and by the surfaces of the piston, are each semi-circularly 
wedge-shaped. 
With the oscillating piston compressor immediately above described, the 
wedge shape of the compression chambers necessarily results from the 
wedge-shaped or angled cover-valve plate, while the piston represents a 
uniform disk having a circular peripheral support surface. The spherical 
recess in the cylinder housing required by the wedge shape of the 
cover-valve plate provides an elliptical sealing surface, due to which, 
difficulties can originate with the manufacture thereof and which can also 
affect the manufacture of the cover-valve plate and the cylinder cover. 
SUMMARY OF THE INVENTION 
It is the object of the present invention, therefore, to improve the 
oscillating piston compressor mentioned at the outset with simple means so 
that the indicated production difficulties can be eliminated. This problem 
is solved by the present invention in the manner set forth below. 
The design of the cover-valve plate in a flat form results in a flat 
sealing surface between the cylinder housing and the cover-valve plate, 
which is more favorable for production cost, and creates no problems with 
respect to sealing. On the other hand, no essential difference exists in 
producing the oscillating piston in angled form as compared to producing 
it in a flat form. 
The invention can be advantageously used commercially in the small 
compressor range, e.g., in dentistry, compressed air tools or as a 
combination vacuum pump/air compressor.

DESCRIPTION AND OPERATION 
According to FIG. 1, an oscillating piston compressor embodying the 
invention, comprises a housing 1 with a substantially semi-spherical inner 
chamber, the outside contour of which housing can be round or angular 
while said inner chamber is characterized by a spherical inner contour 2 
in that portion in which oscillating motion of a wedge-shaped oscillating 
piston 3 occurs. The geometric center point of the inner contour 2 is 
designed to coincide with the axis of a bearing axle 4 of the oscillating 
piston 3. Bearings (not shown) for the oscillating piston bearing axle 4, 
may be fixed either in housing 1 or in the oscillating piston 3. On the 
one side of oscillating piston 3, there is a crankarm 5 having a follower 
6 secured at the end thereof and, as shown in FIG. 1, in contact with one 
(7) of two high points or elevations 7 and 8 of a cylindrical undulating 
cam surface 8a of the oscillating piston 3. 
The oscillating motion of piston 3 about the axis of axle 4 is effected by 
means of a driveshaft 9 rotatably journaled in housing 1. On the side of 
the oscillating piston 3 opposite crankarm 5, there is a valve plate 10, 
which is clamped between the cylinder housing 1 and a cylinder head 11 
provided with a delivery connection (not shown) and an intake or suction 
connection 12. Cross members 13 and 14 of cylinder head 11 form two 
exhaust or delivery valves 10-15 and 10-16 correlated with respective 
compression chambers I and II, and with valve plate 10 and exhaust disk 
valves 15 and 16, whereby compression chambers I and II are defined by the 
areas of oscillating piston 3 disposed on both sides of a center vertical 
axis 17, contour surface 2, and valve plate 10. Between the cylinder head 
11 and valve plate 10, there is a common pressure delivery chamber III 
opening to a delivery connection (not shown) leading to fluid pressure 
devices using the fluid pressure generated by the compressor. 
Compression chambers I and II are connected with respective intake valves 
10-18 and 10-19, comprising intake disk valves 18 and 19 and valve plate 
10, to common intake connection 12 via chamber III. Sealing of compression 
chambers I and II between the rotating piston 3 and the circular arc 2 is 
achieved by annular sealing elements 20 and a packing strip 21 
diametrically disposed in the apex juncture of the two halves of piston 3. 
Compressing operation of the compressor shown in FIG. 1 is effected by 
rotation of crankshaft 9 and therefore rotation of crankarm 5. Follower 6 
imparts motion to cam surface 8a and oscillation of piston 3. 
The basic design of the oscillating piston compressor shown in FIG. 2 is 
practically the same as that of the compressor shown in FIG. 1, except 
that the driving means comprises a camshaft 22 rotatably journaled in 
housing 1. A pair of eccentric cams 23 and 23a are carried at 180.degree. 
relative to each other on camshaft 22 and ride on diametrically disposed 
undulated cam surfaces 24 and 24a, respectively, formed on the underside 
of piston 3 to impart oscillating motion to said piston upon rotation of 
the camshaft. FIG. 3 also corresponds basically to the basic design shown 
in FIG. 1, except that the drive means comprises a crankshaft 25 having 
one end of a crankpin 26 eccentrically mounted thereon with the other end 
of said crankpin rotatably connected to one sector of piston 3 for 
imparting oscillating motion thereto upon rotation of said crankshaft. 
The function of the oscillating piston compressor is as follows: 
Atmospheric air flows through the housing opening 12 into a supply chamber 
IV and is drawn into pressure chamber I or II through suction valve 10-18 
or 10-19, so that piston 3 is moved in the direction of the lower dead 
center position. The compressed air produced by oscillation of piston 3 
from the lower dead center position to an upper dead center position, as 
effected through the connection between crankshaft 25 and crankpin 26, 
flows through exhaust valve 10-15 or 10-16 to delivery chamber III and 
from there through housing opening 12 to the pressure operable devices 
(not shown). 
The oscillating piston machine, described here in the form of a compressor, 
as design example, can be designed further with the same chamber 
arrangement as a combustion machine. 
The oscillating piston compressor may be designed as a dual or compound 
compressor with a common camshaft drive, as shown in FIG. 4, or with a 
crankshaft drive, even making it possible to have a four-, six-, or 
multi-chambered compressor by connecting on further double-chamber 
oscillating piston compressors, whereby such a series of compressors makes 
possible an arrangement of the cylinders in rows and a rotation free 
connection of the camshaft or the crankshaft, and with such design, the 
cylinders lie opposite each other and the oscillating pistons may be 
actuated by a common camshaft or crankshaft.