U.S. patent number 3,680,987 [Application Number 05/045,953] was granted by the patent office on 1972-08-01 for rotary piston engine.
This patent grant is currently assigned to Danfoss A/S. Invention is credited to Carl V. Ohrberg.
United States Patent |
3,680,987 |
Ohrberg |
August 1, 1972 |
ROTARY PISTON ENGINE
Abstract
The invention relates to a rotary piston engine of the type
having an internally toothed ring and an externally toothed wheel
which is orbitably and rotatably movable relative to the ring. The
motor has a disk shaped valve which is driven by the externally
toothed wheel through a universal joint shaft. In order that the
shaft only applies torque to the valve, to the exclusion of any
axially directed force, the valve has a splined bore and is
journalled on a cylindrically shaped abutment which is fixed
relative to the casing. The shaft has a splined head which engages
the splined bore of the valve to effect rotation of the valve but
the shaft head is in axial thrust engagement with the abutment so
that no axial forces are transmitted to the valve. The valve and
casing parts are appropriately and uniquely disigned with
cooperating annular recesses so that axially directed hydraulic
forces on the valve are also minimized. The overall result is that
there is no mechanical axial loading of the valve and little or no
hydraulic axial loading of the valve.
Inventors: |
Ohrberg; Carl V. (Havnbjerg,
DK) |
Assignee: |
Danfoss A/S (Nordborg,
DK)
|
Family
ID: |
5737447 |
Appl.
No.: |
05/045,953 |
Filed: |
June 15, 1970 |
Foreign Application Priority Data
|
|
|
|
|
Jun 19, 1969 [DT] |
|
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P 19 31 144.5 |
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Current U.S.
Class: |
418/61.3 |
Current CPC
Class: |
F01C
1/10 (20130101); F04C 2/104 (20130101); F02B
53/00 (20130101); Y02T 10/12 (20130101); F02B
2730/01 (20130101); Y02T 10/17 (20130101) |
Current International
Class: |
F01C
1/00 (20060101); F01C 1/10 (20060101); F04C
2/00 (20060101); F04C 2/10 (20060101); F02B
53/00 (20060101); F01c 001/02 (); F03c 003/00 ();
F04c 001/02 () |
Field of
Search: |
;418/61,75,81 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Croyle; Carlton R.
Assistant Examiner: Vrablik; John J.
Claims
I claim:
1. A rotary piston motor comprising a casing, an internally toothed
ring in fixed relation to said casing, an externally toothed wheel
cooperable with said ring and being orbitably and rotatably movable
relative to the axis of said ring, a disk shaped valve mounted for
rotation relative to the axis of said ring, said wheel and said
valve each having a centrally disposed splined bore, a universal
joint shaft having splined heads at opposite ends thereof in
meshing engagement respectively with said wheel and valve splined
bores, an abutment member in abutting engagement with an internal
wall of said casing and extending part way into said splined bore
of said valve for axial thrust engagement with the adjacent one of
said splined heads, said abutment member having a cylindrically
shaped surface in engagement with said valve bore for supporting
said valve for rotation about the axis of said ring.
Description
The invention relates to a rotary piston engine, in which
displacement chambers are formed between an externally toothed
wheel and an internally toothed ring, and the toothed wheel is
connected, through a universal joint shaft independent of the main
shaft, to a rotary slide valve, which, together with a valve part
connected to the toothed ring, forms a distributing valve, the
universal joint shaft being connected, by means of a toothed
portion, to the toothed wheel so that it rotates therewith.
German Patent Specification 1198750 discloses a rotary piston
engine of this kind which can be used as a pump or a motor. In this
engine the rotary movement of the toothed wheel is transmitted
through a universal joint shaft to the main shaft (or vice versa).
The charging and voiding cycle of the displacement chambers,
however, takes place at a considerably greater rate, i.e., at the
speed of rotation of the center point of the toothed wheel about
the center point of the toothed ring. For this purpose there is
provided a sleeve-like rotary piston valve which is connected by
way of a second universal joint shaft to the toothed wheel. It
cooperates with apertures in the casing each of which leads to the
root of a tooth. Distributed over the periphery of the rotary slide
valve are openings which are alternately connected to the pressure
and the low-pressure sides of the engine and the number of which is
twice as great as the number of teeth on the toothed wheel. Both
universal joint shafts are connected, by means of the toothed
portion, to the toothed wheel so as to rotate therewith. In each
case, the free ends of the universal joint shafts engage the main
shaft and the sleeve-like rotary slide valve respectively, by way
of link-pin connections.
Instead of the sleeve-like rotary valve, in which the effective
apertures are disposed on a peripheral surface, it is often
required to use a disc-shaped rotary slide valve, in which the
effective apertures are contained in an end-face. In the case of a
disc-shaped rotary slide valve, larger cross-sections of aperture
can be used, since the disc can be of greater diameter.
Furthermore, the use of a disc-shaped rotary slide valve results in
a reduction in the axial length of the construction. However, tests
have shown that it is not possible to substitute, in the initially
described rotary piston engine, a disc-shaped rotary slide valve
for the sleeve-shaped rotary slide valve while retaining the other
features of the principle of construction. When this substitution
was tried the system jammed and very heavy wear occurred.
The object of the invention is to provide a rotary piston engine of
the initially described kind that is reliable in operation and
incorporates a disc-shaped rotary slide valve instead of a
sleeve-shaped one.
According to the invention, this object is achieved by forming the
rotary slide valve as a disc, by connecting the universal joint
shaft to the rotary slide valve so that it rotates therewith and is
enabled to execute axial movement, and by providing a stop,
connected to the toothed ring, for that end-face of the universal
joint shaft associated with the rotary slide valve.
This construction results from the surprising discovery that during
the orbital movement of the center-point of the toothed wheel, the
toothed construction between the wheel and the universal joint
shaft leads to axial movement of this shaft and, in extreme cases,
even to the universal joint shaft being pushed out of the wheel.
If, in known manner, the universal joint shaft is connected to the
rotary slide valve by way of a journal, this valve must also
execute this axial movement. Such axial play was permissible in the
case of a sleeve-shaped rotary slide valve; a disc-shaped valve,
however, must maintain its axial position, since otherwise the
sealing effect ceases and jamming occurs. In accordance with the
invention, only torque can be transmitted from the universal joint
shaft to the rotary slide valve; the rotary slide valve does not
however need to take up axial forces. Instead, these axial forces
are taken up by the stop. Consequently, the universal joint shaft
cannot move out of the toothed wheel.
In the simplest case, the toothed ring and the stop are secured to
the casing. The stop can simply be part of the casing.
Expediently, the universal joint shaft and the rotary slide valve
can be interconnected to rotate with each other by means of a
toothed arrangement. Then, both ends of the universal joint shaft
can be of the same shape. As is well known, the toothed
construction permits axial displacement.
To enable the universal joint shaft to engage roughly at the center
of the rotary slide valve, it is advisable for the stop to take the
form of a plug extending into the rotary slide valve.
If the diameter of this plug is the same as that of the bore of the
rotary slide valve, the valve can be mounted on the plug. In
contrast to mounting the valve by its periphery, this offers the
advantage that only low circumferential speeds occur at the
bearing.
In a further form of the invention, a cut-off passage in the rotary
slide valve should lead from each control opening to the opposite
face of the slide valve, and recesses that mirror the orifices in
the valve part should be provided in the component bearing against
said slide valve face. In this way pressure is relieved at the
orifices in the valve part.
Furthermore, all even-numbered openings can be interconnected by an
outer annular groove, and all odd-numbered openings by an inner
annular groove in that end face of the rotary slide valve presented
to the valve part, and these openings can be connected to the
associated unions through annular grooves which have approximately
the same radius as the first-mentioned annular grooves in the
opposite component. In this way, those pressure effects stemming
from the annular supply grooves are eliminated.
The rotary slide valve is then relieved overall not only of the
mechanical forces stemming from the universal joint shaft, but also
of the hydraulic forces deriving from the pressure medium.
An embodiment of the invention will now be described in greater
detail by reference to the drawing, in which:
FIG. 1 shows a longitudinal section through a rotary piston engine
designed in accordance with the invention,
FIG. 2 is a cross-section on the line A--A of FIG. 1, and
FIG. 3 is a cross-section on the line B--B of FIG. 1.
The casing of the rotary piston engine illustrated consists of a
bearing portion 1, an intermediate part 2, a side portion 3, an
outer ring 4, a second side portion 5, a slide plate 6, a casing
ring 7 and a connecting cover-plate 8. The parts 1-5 are
interconnected by screw-bolts 9, and the parts 4-8 by screw-bolts
10. A main shaft 11 is mounted in bearings 12 and 13 in the bearing
portion 1. A universal joint shaft 14, the two ends of which engage
by an outer toothed portion with a corresponding inner toothed
portion, connect the main shaft 11 to the internally toothed wheel
15. This toothed wheel is in an engagement with rollers 16, which
are rotatably mounted in bearings 17 and 18 in the side portions 3
and 5 and are arranged in recesses 19 in the outer ring 4, there
being a clearance between the roller and the outer ring. Thus,
between the teeth of the toothed wheel 15, the roller 16, the other
outer ring 4 and the two side portions 3 and 5, there are formed
displacement chambers 20, which increase and diminish in size
cyclically upon each revolution of the toothed wheel 15.
Sliding seals 21 are contained in grooves 22 in the outer ring 4,
and are urged against the peripheral surface of each of the rollers
16 by a leaf spring 23 or the pressure obtaining in the chamber 24.
In this way a perfect seal is achieved between adjacent
displacement chambers 20 despite the clearance between each roller
16 and each recess 19.
The chambers 24 below the sliding seals 21 are interconnected by
way of an annular groove 25 in the side portion 5. This annular
groove communicates, by way of axial passages 26, with an annular
groove 27, which in turn communicates, by way of two similar paths,
with the unions 28 and 29 in the cover 8. Only one of these parts
is shown. It consists of an axial bore 30 in the slide plate 6, a
non-return valve 31 in the casing ring 7 and a connecting passage
32 in the cover 8. The non-return valve ensures that even if the
engine operates on a reversible system, the side under higher
pressure communicates with the chambers 24 each time.
An axial passage 33 in the side portion 5 terminates at a
displacement chamber 20 between each two rollers 16, and each axial
passage 33 is continued as an axial passage 34 in the slide part 6.
Since in the present case, nine rollers 16 are present, there are
also nine such passages 33 and 34. Cooperating with the ends of the
passages 34 is a rotary slide valve 35 which is driven at the same
speed as the toothed wheel 15 by a universal joint shaft 36, the
two ends of which likewise engage by an outer toothed arrangement
in a corresponding inner toothed arrangement. The rotary slide 35
is mounted on a plug 37 which is held in the cover 8. The rotary
slide valve contains eight openings 38, which are connected to the
union 28 by way of an annular groove 39, and between each pair of
these openings 38, the rotary slide valve contains eight openings
40 which are connected to the union 29 by way of an annular groove
41. In this way, the rotary slide valve 35 and the slide plate 6
constitute a commutating valve, which performs the function of
connecting the displacement chambers 20 to the pressure or
low-pressure side of the engine in the correct sequence.
To relieve the rotary slide valve of load, the openings 38 on the
side opposite the annular groove 39 are interconnected by an
annular groove 42, and the openings 40 on the side opposite the
annular groove 41 are interconnected by an annular groove 43. Also,
opposite each of the passages 34, a surface 44, similar to the
mouths is recessed in the cover 8, and a cut-off passage 45 leads
from each opening 38,40 to an end-face of the cover 8, so that the
same pressure obtains in the recesses 44 as at the mouths of the
passages 34. The recesses 44 are shown in broken lines in FIG. 3;
this Figure also shows that the cut-off passages 45 each have a
widened portion 45a at the end face, which portion is equal to the
width of the openings 38 and 40.
When the universal joint shaft 36 rotates, it can apply an axial
pressure towards the right because of the toothed construction.
This pressure is taken up by the end face of the plug 37 and is
therefore not transmitted to the slide valve 35. Since the slide
valve is also largely relieved of pressure, it operates without
jamming at all and with the least possible amount of friction.
All chambers into which a leakage oil can penetrate, particularly
the central chambers 46, the bearing chamber 47 and the chamber 48
outside the rotary slide valve are interconnected through passages
49, 50 and 51. The cover 8 contains two non-return valves, not
illustrated, by means of which leaking oil is passed in each case
to the low-pressure unions.
* * * * *