U.S. patent application number 12/093163 was filed with the patent office on 2008-10-16 for hydrostatic piston machine.
This patent application is currently assigned to BRUENINGHAUS HYDROMATIK GMBH. Invention is credited to Marcus Herrmann, Werner Hoermann, Georg Jacobs.
Application Number | 20080250920 12/093163 |
Document ID | / |
Family ID | 37684042 |
Filed Date | 2008-10-16 |
United States Patent
Application |
20080250920 |
Kind Code |
A1 |
Herrmann; Marcus ; et
al. |
October 16, 2008 |
Hydrostatic Piston Machine
Abstract
The invention relates to a hydrostatic piston machine (1) having
a drive shaft (2) which passes through a cylinder-drum unit.
Cylindrical clearances (18, 19) are disposed in said cylinder-drum
unit. Pistons (16, 17), which are disposed in a displaceable manner
in said cylinder clearances (18, 19), are connected to the drive
shaft (2) in a torsion-proof manner. The cylinder-drum unit is
centred on a bearing (32, 32') provided on the drive shaft (2).
Said cylinder-drum unit consists of a cylinder drum (20, 21) having
a number of cylindrical clearances (18, 19) constructed
therein.
Inventors: |
Herrmann; Marcus;
(Elchingen, DE) ; Hoermann; Werner; (Illertissen,
DE) ; Jacobs; Georg; (Ulm, DE) |
Correspondence
Address: |
SCULLY SCOTT MURPHY & PRESSER, PC
400 GARDEN CITY PLAZA, SUITE 300
GARDEN CITY
NY
11530
US
|
Assignee: |
BRUENINGHAUS HYDROMATIK
GMBH
Elchingen
DE
|
Family ID: |
37684042 |
Appl. No.: |
12/093163 |
Filed: |
November 9, 2006 |
PCT Filed: |
November 9, 2006 |
PCT NO: |
PCT/EP2006/010768 |
371 Date: |
May 9, 2008 |
Current U.S.
Class: |
91/498 |
Current CPC
Class: |
F04B 1/2035
20130101 |
Class at
Publication: |
91/498 |
International
Class: |
F01B 13/06 20060101
F01B013/06 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 11, 2005 |
DE |
10 2005 053 932.7 |
Dec 9, 2005 |
DE |
10 2005 058 938.3 |
Claims
1. Hydrostatic piston machine having a drive shaft which passes
through a cylinder-drum unit in which there are disposed
cylindrical clearances in which pistons connected to said drive
shaft in a torsion-proof manner are disposed, wherein the
cylinder-drum unit is centred on a bearing provided on the drive
shaft, wherein the cylinder-drum unit is constructed as a cylinder
drum having a number of cylindrical clearances constructed
therein.
2. Hydrostatic piston machine according to claim 1, wherein the
pistons are connected to the drive shaft via an articulated
connection.
3. Hydrostatic piston machine according to claim 2, wherein the
pistons have a spherical head which is disposed in a corresponding
spherical clearance in a carrier plate connected to the drive
shaft.
4. Hydrostatic piston machine according to claim 1 one wherein the
pistons have a conical section disposed between a sealing section
their connection to the drive shaft.
5. Hydrostatic piston machine according to claim 1 wherein the
cylinder drum has a central through-aperture which interacts in a
centring manner with the bearing on the drive shaft.
6. Hydrostatic piston machine according to claim 5, wherein the
bearing on the drive shaft is constructed as a spherical
drive-shaft section.
7. Hydrostatic piston machine according to claim 6, wherein there
is provided, in the region of the spherical drive-shaft section, at
least one entraining element by which the drive shaft and the
cylinder drum are connected to one another in a torsion-proof
manner.
8. Hydrostatic piston machine according to claim 7, wherein the
entraining element is fixed in the drive shaft and engages in an
entraining groove in the cylinder drum.
9. Hydrostatic piston machine according to claim 7, the entraining
element is fixed in the cylinder drum and engages in an entraining
groove in the drive shaft.
10. Hydrostatic piston machine according to claim 1 wherein a
sealing section having a piston ring is constructed on the
pistons.
11. Hydrostatic piston machine according to claim 1 wherein the
pistons have a spherical outer contour in the region of their
sealing section.
12. Hydrostatic piston machine according to claim 1 wherein in the
region of their sealing section, the pistons have a thin-walled
piston shaft which can be expanded elastically by the internal
pressure in the cylinder.
13. Hydrostatic piston machine according to claim 1 wherein the
pistons are fixed in the axial direction by a retraction disc.
Description
[0001] The invention relates to a hydrostatic piston machine with a
cylinder-drum unit which has a drive shaft passing through it,
pistons being disposed on said drive shaft in a torsion-proof
manner.
[0002] A hydrostatic piston machine in which a drive shaft passes
through a first and a second cylinder-drum unit is known from
PCT/NL03/00017. A carrier plate is fixed on the drive shaft
symmetrically between the two cylinder-drum units. Pistons which
are displaceably mounted in cylinder spaces in the cylinder-drum
units are disposed opposite one another on the carrier plate. The
axis of rotation of each of said cylinder-drum units is at an angle
with respect to the angle of the drive shaft. In this way, the
pistons, which are connected to the drive shaft in a torsion-proof
manner, execute a stroke-type movement within the cylinder spaces.
Said cylinder spaces are constructed in individual cylinders which
are supported on a common drum plate and form a cylinder unit with
the latter. In order to prevent the cylinders from lifting off the
drum plate, a retaining device, which permits a radial movement of
the cylinders, is constructed. This arrangement, which is
universally displaceable, permits a compensating movement of the
cylinders which is necessary because of the fixed arrangement of
pistons in the carrier plate and the angle of inclination of the
cylinder-drum unit in relation to the axis of the drive shaft.
[0003] The arrangement described has the disadvantage, especially
at high rotational speeds, that the centrifugal forces which are
operating lead to a pitching moment on the part of the cylinders.
Although the cylinders are individually held in contact with the
drum plate via a retaining device, a considerable degree of wear
nevertheless occurs because of the large number of parts which
move, relative to one another, since there is only a small bearing
face on the cylinders for the forces which are operating.
[0004] It is the object of the invention to provide a hydrostatic
piston machine in which the aforesaid disadvantages, which come
about as a result of the large number of interacting components of
the cylinder-drum unit, are avoided.
[0005] In the hydrostatic piston machine according to the invention
having the features according to claim 1, the cylinder-drum unit
likewise has a drive shaft passing through it. Pistons which
penetrate into the cylindrical clearances in the cylinder-drum unit
are connected to the drive shaft in a torsion-proof manner. In
contrast to the prior art, the cylindrical clearances are disposed
jointly in a cylinder drum which forms the cylinder-drum unit. This
cylinder drum, which is thereby designed in a compact form, is
centred, as a whole, on a bearing provided on the drive shaft. The
individual cylindrical clearances in the cylinder drum thus do not
execute any independent movements. On the contrary, centring of the
entire cylinder drum, relative to the axis of rotation of the drive
shaft, is achieved. As a result of the one-piece design of the
cylinder drum itself, the individual cylindrical clearances
likewise cannot execute any pitching movement when centrifugal
forces occur.
[0006] Because the pitching movement of the individual cylinders is
prevented, the wear that sets in will be reduced. Also avoided, in
particular, is canting in the direction of rotation, such as can
occur in the individual cylinders when the rotating movement of the
cylinder-drum unit is brought about by the pistons disposed in the
cylinders.
[0007] Advantageous further developments of the hydrostatic piston
machine according to the invention are represented in the
subclaims. It is of particular advantage to connect the pistons to
the drive shaft via an articulated connection. The torsion-proof
connection of the pistons to the drive shaft via an articulated
connection has the advantage that omnidirectional compensation does
not have to take place by displacement of the cylinders. On the
contrary, the compensating movement is achieved by the pistons
having a different inclination, relative to the axis of the drive
shaft, this being made possible by the articulated connection.
[0008] It is also advantageous to provide the piston, for this
purpose, with a spherical head which engages in a corresponding
spherical clearance in the drive shaft, or in a carrier plate
connected to said drive shaft. In this case, the carrier plate may
be designed as a radial widened portion on the drive shaft itself,
for example as a one-piece forging. It is equally conceivable to
provide the drive shaft with a toothing system which is in
engagement with a separately manufactured carrier plate, and thus
forms a torsion-proof connection to the latter. As a result of the
construction of the articulated connection between the piston and
the drive shaft, inclination of the axis of the piston with respect
to the axis of the drive shaft is possible. At the same time, a
direct, torsion-proof connection between the drive shaft and the
piston is achieved as a result of the pistons being fixed, in the
form of a ball joint, on the carrier plate.
[0009] In order to prevent rotation being blocked by contact of the
piston shaft against the inner wall of the cylinder when the
pistons penetrate into the cylindrical clearances, a conical
section is constructed between a sealing section and the
articulated connection on the pistons. The angle of opening of the
conical section preferably corresponds to the intended maximum
angle of inclination of the cylinder drum.
[0010] Centring of said cylinder drum is preferably achieved by
means of a bearing which is constructed on the drive shaft. For
this purpose, a central through-aperture in the cylinder drum,
which is preferably designed as a bore, interacts in a centring
manner with a bearing disposed on the drive shaft. Under these
circumstances, the bearing is preferably constructed, on the drive
shaft side, as a spherical drive-shaft section.
[0011] According to one simple form of embodiment, the torque
between the cylinder drum and the drive shaft can come about
through the pistons disposed in the cylindrical clearances.
According to one preferred form of embodiment, however, an
entraining element is provided between the spherical drive-shaft
section and the cylinder drum. The cylinder drum and the spherical
section of the drive shaft are connected to one another in a
torsion-proof manner by the said entraining element. Under these
circumstances, it is particularly preferred if the entraining
element is fixed in the drive shaft and engages in an entraining
groove in the cylinder drum. The construction of an entraining
groove in the through-aperture in the cylinder drum guarantees that
the angle of inclination of the axis of said cylinder drum can be
varied relative to the axis of rotation of the drive shaft.
[0012] Instead of disposing the entraining element in the region of
the spherical drive-shaft section, it is also conceivably possible
to dispose it in a fixed manner in the cylinder drum. An entraining
groove is then accordingly disposed in said spherical drive-shaft
section. It is also possible to provide a number of entraining
elements which are preferably distributed uniformly over the
periphery.
[0013] In order to obtain the best possible sealing action, piston
rings are preferably disposed on the pistons in a sealing section
of the latter. Said pistons rings are designed, for example, as
steel rings which are inserted in a corresponding groove on the
side of the pistons in the region of the sealing section. The
piston rings are preferably likewise of spherical design on their
outer contour.
[0014] Another possible way of improving the sealing action between
the pistons and the corresponding cylindrical clearance is to
construct a thin-walled piston shaft in the region of the sealing
section. A thin-walled piston shaft of this kind in the region of
the sealing section enables the pressure prevailing in the interior
of the cylinder to expand said piston shaft elastically, as a
result of which its outer contour is applied against the
cylindrical clearance in a sealing manner. This can be carried out
in a particularly simple way by means of a clearance in the piston,
which clearance is located on the side that faces away from the
articulated connection.
[0015] In order to prevent the pistons from lifting off the carrier
plate during the intake stroke, a retraction disc which fixes the
pistons on said carrier plate in the axial direction is preferably
provided. Under these circumstances, said retraction disc is
disposed in such a way that the inclination of the pistons relative
to the carrier plate is not hindered. Said retraction disc encloses
the pistons in such a way that it acts as a constituent part of the
articulated connection. For this purpose, clearances in the
retraction disc are provided which accommodate the head of the
pistons and have a spherical contour.
[0016] A preferred exemplified embodiment of the hydrostatic piston
machine according to the invention is represented in the drawings
and will be represented in a detailed manner in the following
description. In said drawings:
[0017] FIG. 1 shows a longitudinal section through a first
exemplified embodiment of a hydrostatic piston machine according to
the invention;
[0018] FIG. 2 shows a longitudinal section through a second
exemplified embodiment of a hydrostatic piston machine according to
the invention; and
[0019] FIG. 3 an enlarged representation of the part III of FIG.
2.
[0020] A longitudinal section through a first exemplified
embodiment of a hydrostatic piston machine 1 according to the
invention is represented in FIG. 1. Said hydrostatic piston machine
1 has a drive shaft 2 which is mounted in a housing formed from a
first half 3 and a second half 4. The first half 3 of the housing
and the second half 4 of said housing are of approximately
pot-shaped construction. Under these circumstances, a
through-aperture 5 is constructed in the first half 3 of the
housing. In the exemplified embodiment represented, said
through-aperture 5 is designed as a stepped bore. An end of the
drive shaft 2 which is provided with a toothing system 6 protrudes
through said through-aperture 5.
[0021] A first drive-shaft bearing 7 is disposed in the stepped
through-aperture 5. Said first drive-shaft bearing 7 is designed as
a tapered-roller bearing. Also provided in the stepped
through-aperture 5 is a sealing element which seals the drive shaft
2 in relation to the first part 3 of the housing.
[0022] At the opposite end of the housing, a stepped blind bore 8
is constructed in the second part 4 of said housing. A second
drive-shaft bearing 9, which is likewise constructed as a
tapered-roller bearing, is disposed in that part of said stepped
blind bore 8 which is oriented towards the interior space of the
housing.
[0023] The first part 3 and the second part 4 of the housing each
have a circumferential flange, 10 and 11 respectively. The first
part 3 and the second part 4 of the housing are screwed to one
another at the flanges 10, 11 with the aid of screws 12.
[0024] A carrier plate 13 is disposed, approximately centrally in
the interior of the housing, on the drive shaft 2. In the
exemplified embodiment represented, said carrier plate 13 is
designed in one piece with said drive shaft 2. Spherical clearances
14, 15 are incorporated, in the form of joint sockets, in the
carrier plate 13 on both sides. Pistons 16, 17 having ball-shaped
heads disposed at their ends are inserted in said spherical
clearances 14, 15. The articulated connection thus produced between
the pistons and the carrier plate 13 will be explained again in
detail below with reference to FIG. 3. The pistons 16 and 17 are of
identical design. For the sake of clarity, the reference numerals
16 and 17 each designate just one piston of the group of pistons
which interact with a cylinder drum 20, 21.
[0025] The pistons 16, 17 protrude, with their end that faces away
from the articulated connection between the pistons 16, 17 and the
carrier plate 13, into cylindrical clearances 18, 19 in a first
cylinder drum 20 and a second cylinder drum 21, respectively.
Within said cylinder drums 20, 21, a plurality of cylindrical
clearances, 18 and 19 respectively, are disposed, parallel to one
another, over a first and a second peripheral circle, respectively.
The common peripheral circle of the first cylinder drum 20 and the
common peripheral circle of the second cylinder drum 21 are
preferably identical and correspond to the peripheral circles on
which the spherical clearances 14, 15 on the carrier plate 13 are
disposed.
[0026] A cylindrical volume is enclosed, in each case, between the
cylindrical clearances, 18 and 19 respectively, on one common
peripheral circle each, and the corresponding pistons (16, 17)
disposed therein. The cylinder drums 20, 21 are disposed in an
inclined manner in relation to the axis of rotation of the drive
shaft 2. When a rotation of the cylinder drums 20, 21 and also of
the drive shaft 2 occurs, the pistons, 16 and 17 respectively,
execute a stroke-type movement in the corresponding cylindrical
clearances, 18 and 19 respectively, and thereby diminish and
enlarge the enclosed cylindrical volume cyclically. The cylinder
drums 20 and 21 are each supported on a slanting disc, 22 and 23
respectively. In the exemplified embodiment represented, said
slanting discs 22, 23 are disposed in a fixed manner, so that a
constant angle of inclination of the first and second cylinder
drums 20, 21 in relation to the axis of the drive shaft 2 is set
up. However, it is equally possible to support the cylinder drums
20, 21 against one adjustable slanting disc each and to thus design
the stroke volume in a settable manner. In this case, it is
possible, in particular, to provide independent adjustment of the
inclinations of the first cylinder drum and second cylinder drum,
20 and 21 respectively. Another possibility is to provide one of
the cylinder drums, 20 or 21, with a fixedly set angle and to
provide the other cylinder drum 20, 21, in each case, with an angle
of pivoting which can be changed.
[0027] The exemplified embodiments represented relate, in each
case, to double pumps or double motors. In the figures, features
which are explained only for one side are provided, on the opposite
side, with a corresponding reference numeral having an
apostrophe.
[0028] The following embodiments relate to that unit of the machine
which is represented on the left-hand side in FIG. 1 and consists
of the slanting disc 22, the first cylinder drum 20 and the pistons
16 which execute a stroke-type movement therein. The embodiments
relate, in an analogous manner, to the second unit of the machine,
which is represented on the right in FIG. 1. The structural
elements which correspond in each case are disposed symmetrically
with respect to a median plane 26.
[0029] The first cylinder drum 20 has a running face 25 by which it
is supported against a supporting face 24 of the slanting disc 22.
In order to secure said slanting disc 22 against twisting, it is
fixed, by means of a locating pin 27, in the first, pot-shaped
housing part 3 on the bottom 30 of the latter. When the cylinder
drum 20 is rotated, the cylindrical clearances 18 can be connected
cyclically, via cylinder apertures 28, to control apertures in the
slanting disc 22 which are not represented. In the exemplified
embodiment represented, an angle of pivoting which is set in a
fixed manner, in each case, for the first cylinder drum 20 and for
the second cylinder drum 21, is provided both for the first
slanting disc 22 and for the second slanting disc 23. The angle of
inclination of the cylinder drums 20, 21 in relation to the axis of
the drive shaft 2 is determined by a wedge shape on the slanting
discs 22, 23. The slanting disc 22 has a bearing face 29, by which
it rests on the bottom 30 of the first part 3 of the housing.
[0030] The first cylinder drum 20 has a central through-aperture 31
which is designed as a cylindrical bore. The first cylinder drum 31
is supported against a bearing on the drive shaft 2 by means of
said central through-aperture 31. The bearing on the drive shaft 2
is constructed as a spherical contoured section 32 on the outer
contour of said drive shaft 2. In the exemplified embodiment
represented, the spherical contoured section 32 is itself directly
produced by the shaping of the drive shaft 2. As a bearing, use may
equally well be made of a superimposed element which has a
spherical outer contour. In this case, use may be made of different
materials for constructing the bearing and for the drive shaft 2
itself, in order to achieve, for example, improved
emergency-running properties in the event of a lack of
lubrication.
[0031] In order to prevent the cylinder drum 20 from lifting off
the slanting disc 22, a spring 33 is provided, which is likewise
supported against the bearing on the drive shaft 2 via a supporting
body 34. For this purpose, said supporting body 34 has a spherical
clearance, in the region of its contact against the bearing on the
drive shaft 2, which corresponds with the spherical contoured
section 32 of said bearing. The outer diameter of the supporting
body 34, which is constructed as a ring, corresponds to the inner
diameter of the central through-aperture 31 of the first cylinder
drum 20. On the side opposite the supporting body 34, the spring 33
is supported against a Seeger ring 35 which is inserted in a groove
in the cylinder drum 20. Said spring 33 generates an axial force in
the direction of the axis of the cylinder drum, which force presses
the running face 25 of the cylinder drum 20 against the supporting
face 24 on the slanting disc 22.
[0032] A retraction disc 36 is provided in order to prevent the
lifting of the pistons 16 out of the spherical clearances 14 in the
carrier plate 13 during an intake stroke. Said retraction disc 36
is, for example, screwed to the carrier plate 13 and fixes the
ball-shaped heads 43 of the pistons 16 in the respective spherical
clearances 14. For this purpose, the retraction disc 36 has a
number of apertures 37 which is identical to the number of pistons
16, which apertures are likewise spherically contoured and
correspond with the outer contour of the ball-shaped head 43 of the
pistons 16. For this purpose, the piston 16 is also ball-shaped in
its region that protrudes beyond the spherical clearance 14.
[0033] The pistons 16 have a lubricating-oil bore 38 which extends
from the bottom 39 of a piston to an opposed, flattened end 40 on
the ball-shaped head 43 of said piston 16. Relief of the
hydrostatic load on the piston 16 in the articulated connection is
achieved by means of the lubricating-oil bore 38.
[0034] The hydrostatic piston machine 1 according to the invention
may be employed both as a pump and as a motor. If it is used as a
pump, the cylinder drums 20, 21 are driven via the toothing system
6. The carrier plate 13, which is designed, in the exemplified
embodiment represented, in one piece with the drive shaft 2, is set
in rotation by the rotating movement transmitted to said drive
shaft 2 by means of the toothing system 6. The pistons 16, 17,
which are connected to the carrier plate 13 in a torsion-proof
manner with respect to rotation about the axis of the drive shaft
2, thus likewise execute a rotation about said axis of the drive
shaft 2. A torque is transmitted to the first cylinder drum 20 and
second cylinder drum 21 via the pistons 16 and 17 respectively.
Said cylinder drums 20, 21 thus execute a rotating movement about
their axes, which are inclined in relation to the axis of the drive
shaft 2. In the process, the cylinder drums 20 and 21 are kept in
contact with the slanting discs, 22 and 23 respectively, by the
springs 33, 331. Because of the inclination of the axes of rotation
of the drive shaft 2 to the cylinder drums 20, 21, the pistons 16,
17 execute stroke-type movements within the corresponding
cylindrical clearances 18, 19, it being possible for the pressure
medium delivered by the variable cylindrical volume during one
revolution to be delivered into the same hydraulic circuit or
different hydraulic circuits.
[0035] In the exemplified embodiment represented in FIG. 1, the
required torque for rotating the cylinder drums 20, 21 is
transmitted by the pistons, 16 and 17 respectively, from the
carrier plate 13 to said cylinder drums 20, 21. In the process,
said pistons 16, 17 execute an inclining movement until a conical
section, 45 and 46 respectively, lying between a sealing section,
41 and 42 respectively, on the pistons, 16 and 17 respectively, and
the ball-shaped head, 43 and 44 respectively, of said pistons 16,
17, is in contact with the cylindrical clearances, 18 and 19
respectively.
[0036] The piston 16 has, adjoining its bottom, a sealing section
41. Said sealing section 41 is of thin-walled construction. In the
exemplified embodiment represented, the thin-walled design of the
sealing section 41 is achieved by means of a clearance 65 which is
incorporated in the piston 16 from the bottom side. The piston 16
is of spherical design in its sealing section 41 at its outer
periphery. A spherical outer contour of this kind may come about,
for example, through the incorporation of a cylindrical clearance
65 in the bottom of the piston, whereupon the thin-walled wall
section 66 is contoured in order to achieve the spherical outer
contour.
[0037] An alternative to the transmission of the torque between the
drive shaft 2 and the cylinder drums 20, 21 is represented in FIG.
2. In FIG. 2, the same reference symbols designate the features
which are already known from FIG. 1. In order to prevent
unnecessary repetition, a further detailed description of the
entire piston machine 1' will be dispensed with.
[0038] In the exemplified embodiment in FIG. 2, entraining elements
50, 51 are provided for transmitting a torque between the drive
shaft 2 and the cylinder drums 20, 21. Said entraining elements 50,
51 are of identical design and act in the same way, between the
drive shaft 2 and the cylinder drums 20, 21, as a
torque-transmitting apparatus. The following remarks are therefore
limited to the entraining element 50 represented on the left in
FIG. 2. The entraining element 50 has a cylindrical section 52.
Said cylindrical section 52 is inserted in a clearance 53. The
depth of said clearance 53 is greater than the length of the
cylindrical section 52 of the entraining element 50. Said
entraining element 50 protrudes radially beyond the spherical
contoured section 32 of the bearing of the drive shaft 2, the
protruding part being constructed as a radially expanded region 54.
An end face 55 of the entraining element 50, which end face is
constructed on said expanded region 54, is likewise contoured in a
spherical manner. In the direction of the longitudinal axis of the
entraining element 50, said end face 55 might be connected to the
opposite end of the entraining element 50 by a duct 57. The
radially expanded region 54 engages in a groove 56 in the cylinder
drum 20.
[0039] As will be explained again later with reference to FIG. 3,
the duct 57 might, as an alternative, be connected, via a
connecting duct 58, to a volume formed in the spherical clearance
14 by the flattened end 40 of the piston 16. In the same way, a
duct 60 in the entraining element 51 might be connected, via a
connecting duct 59, to the corresponding volume which is enclosed
behind the piston 17 in the spherical clearance 15.
[0040] A second, alternative form of embodiment for a sealing
section 411, 42' of the pistons 16, 17 is represented in FIG. 3. In
the sealing section 42', the piston 17 is constructed as a solid
piston 17'. At its end that protrudes into the cylindrical
clearance 19, said solid piston 171 likewise has a spherical outer
contour 67. A groove 68 is incorporated in the sealing section 421
of the solid piston 171 at the transition to a conical section 46.
A sealing ring 69, which interacts with the wall of the cylindrical
clearance 19 in a sealing manner, is inserted in said groove 68.
The piston ring 69 is preferably manufactured from steel, for
example. At its outer face 70 which interacts with the cylindrical
clearance 19, said piston ring 69 is preferably likewise contoured
in a spherical manner.
[0041] In the hydrostatic piston machine 1, 11 according to the
invention, it is advantageous that the cylinder drums 20, 21 are
designed in one piece in each case. This drastically reduces the
portions of the parts which move, relative to one another, and the
high degree of stiffness of the cylinder drums 20, 21 leads to good
absorption of the lateral forces which occur, both because of the
centrifugal forces and also because of internal pressure within the
cylindrical clearances 18, 19. The compensating movement of the
pistons 16, 17 which is required because of the ellipsoidal
movement of the sealing sections 41, 41', 42, 42' of the pistons,
16 and 17 respectively, is brought about in a simple manner by
means of an articulated connection between the carrier plate 13 and
said pistons 16, 17. For this purpose, the pistons 16, 17 are
disposed in the carrier plate 13 by means of a ball-joint-like
connection, and are each fixed to said carrier plate by a
retraction disc, 36 and 361 respectively, for the purpose of
preventing an axial movement during the intake stroke. For its
part, said retraction disc 36, 36' forms, under these
circumstances, part of the articulated connection, through the fact
that the clearances 37, 37' in the retraction discs 36, 36'
interact, for their part, with the ball-shaped head, 43 and 44
respectively, of the pistons, 16 and 17 respectively. In order to
permit slight inclination of the pistons 16, 17, and thereby
rotation of the ball-shaped head, 43 and 44 respectively, within
the spherical clearance, 14 and 15 respectively, relief of the
hydrostatic load on the articulated connections of the pistons 16,
17 is provided.
[0042] As a further alternative, those flat sides of the radially
expanded region 54 of the entraining element 50, 51 which engage in
the groove 56, 56, in the cylinder drum 20, 21, might be
pressure-lubricated.
[0043] A volume, which is filled with pressure medium, is formed in
each case in the spherical clearances 14, 15 in the carrier plate
13 by flattened ends, 40 and 40' respectively, on the pistons 16,
17. This pressure medium is fed to the ducts 57, 60 in the
entraining elements 50, 51 via the connecting ducts 58, 59. A
circumferential supply groove 71 is machined into the entraining
elements 50, 51 in each case, at an orifice of the connecting ducts
58, 59. Said circumferential supply groove 71 ensures that the duct
section 72 provided in the entraining elements, 50 and 51
respectively, is in communication with the connecting ducts, 58 and
59 respectively. It is possible, for example, to provide, in the
entraining elements 50, 51, a number of duct sections 72 which are
distributed over the periphery of said entraining elements 50, 51
and which connect the circumferential groove 71 to the duct, 57 and
60 respectively. In this alternative, the ducts 57, 60 in the
entraining elements 50, 51 are occluded in relation to the end face
55, 55'. The pressure medium fed to the duct 60 via the connecting
duct 59 passes out of the bore 73 in the expanded region 541 of the
entraining element 51 and ensures pressure-lubricated contact faces
of said entraining element 51 within the groove 56' in the cylinder
drum 21.
[0044] The invention is not limited to the exemplified embodiments
represented. On the contrary, it is possible, in particular, to
combine the individual features of said exemplified embodiments
with one another in any desired manner.
* * * * *