U.S. patent number 3,841,801 [Application Number 05/369,928] was granted by the patent office on 1974-10-15 for gerotor type motor with pressure biased rotary valve.
This patent grant is currently assigned to Danfoss A/S. Invention is credited to Carl Verner Ohrberg, Leif Viggo Sturlason.
United States Patent |
3,841,801 |
Sturlason , et al. |
October 15, 1974 |
GEROTOR TYPE MOTOR WITH PRESSURE BIASED ROTARY VALVE
Abstract
The invention relates to a gerotor type rotary piston machine.
The casing has a main axis and the gerotor gear set includes an
externally toothed star member which is rotatable about its own
axis and orbital about the casing main axis. A main drive shaft is
rotatable about the casing axis and a universal type wobble shaft
connects the main shaft to the gerotor star member. An annularly
shaped valve is mounted in said casing for rotation about the
casing main axis. The valve is in surrounding relation to the
wobble shaft and is driven by the wobble shaft. An annularly shaped
pressure plate which is nonrotatable but is capable of a small
amount of axial movement is positioned behind the valve. The
pressure plate is biased against the valve by pressurized fluid
from the inlet port to provide sealing for both sides of the valve.
Sealing rings are provided at the rear of the pressure plate betwen
it and the casing to prevent leakage from the high pressure inlet
regions to the low pressure outlet regions.
Inventors: |
Sturlason; Leif Viggo
(Nordborg, DK), Ohrberg; Carl Verner (Nordborg,
DK) |
Assignee: |
Danfoss A/S (Nordborg,
DK)
|
Family
ID: |
5848031 |
Appl.
No.: |
05/369,928 |
Filed: |
June 14, 1973 |
Foreign Application Priority Data
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|
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Jun 13, 1972 [DT] |
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2229649 |
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Current U.S.
Class: |
418/61.3;
251/175 |
Current CPC
Class: |
B60T
7/206 (20130101); F16D 65/10 (20130101) |
Current International
Class: |
B60T
7/20 (20060101); F16D 65/10 (20060101); F16D
65/02 (20060101); F01c 001/02 (); F03c 003/00 ();
F16k 025/00 () |
Field of
Search: |
;418/61B ;251/175 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Vrablik; John J.
Claims
We claim:
1. A gerotor type rotary piston machine comprising a casing having
a main axis, expansible chamber means having cyclically movable
chamber forming means, rotatable shaft means connected to said
chamber forming means, an annularly shaped valve mounted in said
casing for rotation about said main axis, said valve being in
surrounding relation to said shaft between the opposite ends
thereof, fluid passages in said casing between said valve and said
expansible chamber means, drive means connecting said rotatable
shaft means and said valve in driving relation, said valve having
first and second sets of circumferentially extending and
alternately arranged inlet and outlet ports cooperable with said
casing passages, said second set of valve ports being spaced from
the inner and outer circumferences of said valve, an annularly
shaped pressure plate in abutting engagement with said valve, said
pressure plate being rotationally fixed relative to said casing and
axially movable relative to said valve, said pressure plate having
first and second fluid passage means having fluid communication
with said first and second sets of valve ports, said second fluid
passage means being spaced from the inner and outer circumferences
of said pressure plate, first and second annularly shaped channels
in said casing having respectively fluid communication with said
first and second pressure plate fluid passage means, said second
annularly shaped channel having the mouth thereof in radial
registration with said second fluid passage means, said pressure
plate having first and second surface portions respectively
radially inwardly of said first and second annular channels with at
least one of said surface portions being subjected to pressurized
fluid in either of said annular channels to axially bias said
pressure plate into abutting engagement with said valve.
2. A gerotor type rotary piston machine according to claim 1
wherein said first set of valve passages has the form of recesses
relative to the periphery of said valve.
3. A gerotor type rotary piston machine according to claim 1
wherein said pressure plate first fluid passage means has the form
of recesses relative to the periphery of said pressure plate.
Description
The invention relates to a rotary piston machine with an internal
splined shaft and wherein an internally toothed ring fast with the
casing engages a rotatable externally toothed wheel which is
coupled with a disc shaped rotary slide so as to rotate therewith,
the rotary slide being disposed between a plate having axial ducts
and a part of the casing, which plate and casing part are held in
spaced relationship by a ring on the casing, which ring surrounds
the rotary slide.
Machines of this kind operate as pumps or motors. Since the cycle
of filling and emptying the displacement chambers formed between
the toothed wheel and the toothed ring proceeds at a greater speed
than that at which the main shaft rotates, the machine has as a
pump a large delivery volume and as a motor a large torque. The
valve plate cooperates with the plate having ducts as a distributor
valve in order to supply pressurized fluid to the displacement
chambers and to discharge it therefrom in the correct sequence,
despite the slow speed of revolution of the rotary slide. For this
purpose the rotary slide generally has valve openings, the number
of which is equal to twice the number of teeth on the toothed
wheel, whereas the plate having ducts contains valve openings which
cooperate with the aforementioned valve openings and the number of
which is equal to the number of teeth on the toothed ring.
In a known construction (German Pat. application Ser. No.
1,931,143, as laid open), the rotary slide is inserted between the
plate having ducts and the casing part, in a sliding fit. At higher
pressures however there arises the danger of a slight increase in
the size of the gap between the plate having ducts and the casing
part, particularly as a result of elastic stretching of the axially
extending fixing screws. Consequently, gaps of increased size are
created between the rotary slide and the plate having ducts and the
casing part respectively, and leakage fluid can pass along these
gaps. The quantity of leakage fluid increases with the third power
of the width of gap. This is particularly troublesome in the case
of the rotary slide since the openings at which differing pressures
obtain are located very closely to each other.
The object of the invention is to provide a machine of the above
described kind in which the leakage losses occurring at the rotary
slide can be kept very small.
According to the invention, this object is achieved by providing
between the rotary slide and the casing part a pressure plate which
is non-rotatable but axially displaceable and which has supply and
discharge ducts and, on that of its faces remote from the rotary
slide, a limited annular surface which communicates with the
pressurized port.
In this construction, the pressure plate is acted upon by an axial
force which is equal to the product of the area of the annular
surface and the working pressure of the machine. Consequently, the
pressure plate is pressed against the rotary slide, and the rotary
slide against the plate having ducts. The gaps between these parts
can therefore be kept small and the leakage losses can be kept
correspondingly low. As the working pressure rises, the
pressure-applying force also increases, so that substantially
constant conditions are achieved over the entire working range. The
pressure plate of course covers that end face of the rotary slide
remote from the plate having ducts; however, since the
non-rotatable pressure plate is provided with supply and discharge
ducts, the supply to the rotary slide is not impaired.
It is particularly advantageous if the annular surface adjoins an
annular distributing channel which supplies one set of valve
openings in the rotary slide. Since the one set of valve openings
and therefore also the associated annular distributing channel must
in any case communicate with the pressure port, this arrangement
results in the annular surface being supplied with pressurized
fluid in a very simple manner.
In very many cases a rotary piston machine can be driven in both
rotary directions, and this means that one or other of the ports
can be selectively used as the pressure port. Assuming that this is
so, an extremely simple construction is obtained if two concentric
annular surfaces are present on that face of the pressure plate
remote from the rotary slide, those annular faces being separated
from each other by an O-ring and each of them extending from an
annular distributing channel, the channels each communicating with
a port. It has been found that it generally suffices to use one
half of the end face as the pressure transmitting annular surface,
so that both annular surfaces are located on that face of the
pressure plate remote from the rotary slide.
In a preferred embodiment, one of the annular distributing channels
is of the end face and the other at the peripheral surface of the
pressure plate in the housing part. In this arrangement, one of the
annular surfaces can extend to the outer edge of the pressure plate
and this results in good utilization of space. Furthermore, two
annular distributing channels of relatively large cross section can
be accommodated in the casing part.
Preferably at least one set of the supply and discharge ducts in
the pressure plate is formed by an annular aperture which is
divided by axial partitions. The partitions make it possible for
the pressure plate to be a one piece element despite the presence
of the aperture. These partitions can also contribute towards the
application of pressure to the pressure plate if they extend to the
face of the pressure plate that is presented to the rotary slide.
To ensure correct operation they should then however be disposed
opposite the mouths of the axial ducts in the duct plate.
The invention will now be described in greater detail by reference
to a preferred embodiment illustrated in the annexed drawing which
shows a longitudinal section through a rotary piston machine in
accordance with the invention.
The casing consists of an end plate 1, a casing part 2, a duct
plate 3, a toothed ring 4, and a further end plate 5, these
elements being interconnected by means of screw bolts 6, 7 and 8,
and the gaps between them being closed with the aid of O-rings 9,
10, 11 and 12. A main shaft 13 is mounted in the casing part 2 by
means of a roller bearing unit and in the duct plate 3 by means of
a plain bearing. A sealing element seals off the zone through which
the main shaft 13 projects from the casing. A cavity 14 in the main
shaft 13 accommodates a universal joint shaft 15. The coupling head
16 of this shaft meshes with teeth 17 in the main shaft 13, and a
further coupling head 18 of the shaft meshes with teeth 19 on a
wheel 20 which, by means of teeth in the form of cylindrical
rollers 21, meshes with the toothed ring 4, displacement chambers
being formed between the teeth of the wheel 20 and those of the
ring 4. The outer periphery of the main shaft 13 carries keys 22
which engage in axial grooves 23 in a disc shaped rotary slide 24
and drive this slide.
The casing part 2 has an annular extension 25 which in addition to
surrounding the rotary slide 24 also surrounds a pressure plate 26,
which is prevented from rotating by pins 27 but can move slightly
in the axial direction. Also provided in the casing part 2 are two
ports 28 and 29. The port 28 communicates with an annular
distributing channel 30, and the port 29 with an annular
distributing channel 31. The annular distributing channel 30
extends along the face of the pressure plate 26, and the annular
distributing channel 31 along the outer circumferential surfaces of
this pressure plate 26 and the rotary slide 24. Two O-rings 32 and
33 define a first annular surface 34 which communicates directly
with the annular distributing channel 30. Disposed outwardly of the
O-ring 33 is a second annular surface 35 which extends to the outer
circumference of the pressure plate 23 and communicates directly
with the annular distributing channel 31. The pressure plate has
supply and discharge ducts 36 and 37. These are formed by an
annular aperture which is divided by axial partitions 38. These
partitions extend to that face of the pressure plate presented to
the rotary slide 24 and are disposed where the oppositely
positioned face of the duct plate 3 is not interrupted. The same
applies in the case of the ducts 36 which begin at the periphery of
the pressure plate and likewise have partitions 39.
The rotary slide 24 has valve passages 40 and 41 which communicate
alternately with the annular distributing channel 30 and the
annular distributing channel 31. The number of these passages is
equal to twice the number of teeth on the wheel 20. They form valve
openings which cooperate with corresponding valve openings of axial
ducts 42 in the duct plate 3. The number of these axial ducts is
equal to the number of teeth on the ring, and each terminates at
the outer part of a gap between two teeth fixed in the casing.
If the machine is operated as a motor and is supplied with
pressurized fluid through the port 28, the annular surface 34
transmits pressure. The force thus applied to the pressure plate 26
presses the latter against the rotary slide 24 and presses this
slide against the duct plate 3. The gaps between these parts are
therefore kept small. If pressurized fluid is passed to the port 29
when the direction of rotation is changed, the annular surface 35
transmits the pressure. The annular surface 35 is approximately as
large as the annular surface 34 and likewise leads to compression
of the pressure plate 26, the rotary slide 24 and the duct plate
3.
* * * * *