U.S. patent application number 11/920659 was filed with the patent office on 2009-02-05 for hydrostatic piston machine according to the floating cup concept.
Invention is credited to Marcus Herrmann, Georg Jacobs.
Application Number | 20090031892 11/920659 |
Document ID | / |
Family ID | 36623090 |
Filed Date | 2009-02-05 |
United States Patent
Application |
20090031892 |
Kind Code |
A1 |
Jacobs; Georg ; et
al. |
February 5, 2009 |
Hydrostatic piston machine according to the floating cup
concept
Abstract
The invention relates to a hydrostatic piston engine (1) which
is based on the floating cup principle and comprises a first swash
plate (16) and as well as a second swash plate (17). A first
cylinder drum unit (11, 14) rests against the first swash plate
while a second cylinder drum unit (12, 15) leans on the second
swash plate (17). A first group of pistons (10) and a second group
of pistons (12) are connected in a fixed manner to a drive shaft
(5) of the hydrostatic piston engine (1). The first group of
pistons (10) engages into the cylinder cavities of the first
cylinder drum unit (11, 14) while the pistons (12) of the second
group engage into cylinder cavities of the second cylinder drum
unit (12, 15). The first and second cylinder chambers embodied by
the pistons (10, 12) and the cylinder drum units (11, 14; 12, 15)
can be connected to a first hydraulic circuit and a second
hydraulic circuit, respectively. The axis of rotation of the first
cylinder drum units (11, 14) and/or the axis of rotation of the
second cylinder drum unit (12, 15) can be adjusted independently of
the axis of rotation of the other cylinder drum unit.
Inventors: |
Jacobs; Georg; (Ulm, DE)
; Herrmann; Marcus; (Elchingen, DE) |
Correspondence
Address: |
SCULLY SCOTT MURPHY & PRESSER, PC
400 GARDEN CITY PLAZA, SUITE 300
GARDEN CITY
NY
11530
US
|
Family ID: |
36623090 |
Appl. No.: |
11/920659 |
Filed: |
May 18, 2006 |
PCT Filed: |
May 18, 2006 |
PCT NO: |
PCT/EP2006/004729 |
371 Date: |
November 19, 2007 |
Current U.S.
Class: |
91/499 |
Current CPC
Class: |
F04B 1/22 20130101; F04B
1/2078 20130101 |
Class at
Publication: |
91/499 |
International
Class: |
F01B 3/00 20060101
F01B003/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 20, 2005 |
DE |
10 2005 023 423.2 |
Aug 9, 2005 |
DE |
10 2005 037 618.5 |
Claims
1. Hydrostatic piston machine with a first swash plate on which a
first cylinder drum unit is supported, in the cylinder recesses of
which unit a first group of pistons is arranged, and with a second
swash plate on which a second cylinder drum unit is supported, in
the cylinder recesses of which unit a second group of pistons is
arranged, wherein the pistons of the first group and the pistons of
the second group are connected to a driving shaft of the
hydrostatic piston machine in a rotationally rigid manner, wherein
first cylinder chambers which are formed between the cylinder
recesses of the first cylinder drum unit and the pistons of the
first group can be connected to a first hydraulic circuit, and that
second cylinder chambers which are formed between the cylinder
recesses of the second cylinder drum unit and the pistons of the
second group can be connected to a second hydraulic circuit.
2. Hydrostatic piston machine with a first swash plate on which a
first cylinder drum unit is supported, in the cylinder recesses of
which unit a first group of pistons is arranged, and with a second
swash plate on which a second cylinder drum unit is supported, in
the cylinder recesses of which unit a second group of pistons is
arranged, wherein the pistons of the first group and the pistons of
the second group are connected to a driving shaft of the
hydrostatic piston machine in a rotationally rigid manner, wherein
a first axis of rotation of the first cylinder drum unit and/or a
second axis of rotation of the second cylinder drum unit can be
adjusted independently of the axis of rotation of the respective
other cylinder drum unit.
3. Hydrostatic piston machine according to claim 1 or 2, wherein a
respective swash plate, which can be adjusted in two opposite
directions from its respective neutral position, is provided in
order to adjust the first axis of rotation of the first cylinder
drum unit and/or the second axis of rotation of the second cylinder
drum unit.
4. Hydrostatic piston machine according to claim 1 or 2, wherein
each swash plate co-operates with an adjusting device which
executes a linear actuating movement.
5. Hydrostatic piston machine according to claim 4, wherein the
linear actuating movement can be executed parallel to the driving
shaft.
6. Hydrostatic piston machine according to claim 1 or 2, wherein
pressure medium channels are arranged in the respective first and
second swash plate in order to connect first cylinder chambers
defined by the first cylinder drum unit with the first group of
pistons and second cylinder chambers defined by the second cylinder
drum unit with the second group of pistons to one or a plurality of
hydraulic circuit(s).
7. Hydrostatic piston machine according to claim 6, wherein at
least one respective pressure medium channel of the first and of
the second swash plate, respectively, opens into a working line
channel of a first and second housing flange part,
respectively.
8. Hydrostatic piston machine according to claim 6, wherein the
first swash plate is mounted in a hydrostatically relieved manner
in a first housing flange part and the second swash plate is
mounted in a hydrostatically relieved manner in a second housing
flange part.
9. Hydrostatic piston machine according to claim 8, wherein the
first swash plate is mounted in a sliding manner on a corresponding
first bearing surface in the first housing flange part and the
second swash plate is mounted in a sliding manner on a
corresponding second sliding surface in the second housing flange
part.
10. Hydrostatic piston machine according to claim 6, wherein at
least one working line connection is in each case provided in the
first housing flange part and in the second housing flange part and
connected to the working line connections of a respective feed
valve unit.
11. Hydrostatic piston machine according to claim 10, wherein the
at least one working line connection of the first housing flange
part and the at least one working line connection of the second
housing flange part are arranged towards one side of the
hydrostatic piston machine.
12. Hydrostatic piston machine according to claim 6, wherein the
driving shaft is mounted at least by means of a first driving shaft
bearing in the first housing flange part and by means of a second
driving shaft bearing in the second housing flange part.
13. Hydrostatic piston machine according to claim 1 or 2, wherein
the hydrostatic piston machine comprises a first housing flange
part, a second housing flange part and at least one further housing
part, to which the first and the second housing flange part are
connected.
14. Hydrostatic piston machine according to claim 11, wherein a
common feed pressure channel is arranged in the first housing
flange part, the second housing flange part and the at least one
further housing part.
Description
[0001] The invention relates to a hydrostatic piston machine
according to the floating cup principle.
[0002] Hydrostatic piston machines according to the floating cup
principle are improved with respect to conventional piston machines
in terms of their friction losses. A piston machine of this kind,
which works according to the floating cup principle, is known from
WO 03/058035 A1. The hydrostatic piston machine has a driving shaft
which is arranged in a housing, with an arrangement of pistons
being rigidly connected to the driving shaft via a support plate. A
respective drum plate, on which cylinders are arranged, is likewise
connected to the driving shaft in a rotationally rigid manner for
each group of the pistons projecting from the support plate in the
opposite direction. The axis of rotation of the drum plates is
inclined by the same degree in each case relative to the driving
shaft axis, so that the pistons of the first group as well as of
the second group which are arranged in the cylinders execute a
reciprocating movement relative to the cylinders. Comparable forces
in each case act on the pistons in the axial direction due to the
inclination, which is the same in opposite directions, of the axes
of rotation of the two drum plates.
[0003] The power transmission groups which are formed on both sides
of the support plate by the respective pistons, cylinders and drum
plates deliver into a common hydraulic circuit. The high pressure
sides of the two drum units as well as the low pressure sides of
the two drum units are connected to one another in the housing of
the piston machine for this purpose. The two drum plates are in
each case supported at a swash plate, with the swash plates being
adjustable together.
[0004] The described hydrostatic piston machine entails the
disadvantage of both groups of pistons only delivering into a
common hydraulic circuit and the adjustment of the two swash plates
corresponding with one another. A common adjustment of this kind of
the two swash plates is required in the hydrostatic piston machine
which is known from WO 03/058035 A1 in order to adapt the axial
forces which act on the pistons of both groups to one another.
[0005] However it is not possible to use a piston machine of this
kind in a hydraulic system which comprises two individual circuits
which are to be supplied independently of one another. In this
respect it is neither possible to use the hydrostatic piston
machine to supply two separate hydraulic circuits, for example as a
dual pump, nor is it possible to set a volumetric delivery
individually in each case for the first group of pistons and the
second group of pistons through an independent adjustment of the
two swash plates.
[0006] The object of the invention is to provide a hydrostatic
piston machine according to the floating cup principle in which a
more flexible use is possible by isolating the delivery for the two
power transmission groups.
[0007] The object is achieved by the hydrostatic piston machine
according to the invention with the features of Claim 1 and the
features of Claim 2, respectively.
[0008] The hydrostatic piston machine according to the invention
has two power transmission groups. The first power transmission
group comprises a first swash plate on which a first cylinder drum
unit is supported. A first group of pistons is arranged in the
cylinder recesses of the first cylinder drum unit, these pistons
being connected to a driving shaft of the hydrostatic piston
machine in a rotationally rigid manner. In a corresponding manner a
second power transmission group comprises a second swash plate on
which a second cylinder drum unit is supported. Cylinder recesses,
in which a second group of pistons engage, are likewise arranged in
this second cylinder drum unit. The second group of pistons is
likewise connected to the driving shaft of the hydrostatic piston
machine in a rotationally rigid manner. A first group of cylinder
chambers is formed in the cylinder recesses of the first cylinder
drum unit by the first group of pistons. A second group of cylinder
recesses is accordingly also formed in the cylinder recesses of the
second cylinder drum unit by the second group of pistons. The first
group of cylinder chambers and the second group of cylinder
chambers are in each case connected to an individual hydraulic
circuit in order to obtain two delivery flows of pressure medium.
As a result, the hydrostatic piston machine, which is formed as a
hydraulic pump, for example, delivers through the first power
transmission unit into a first working line and through the second
power transmission unit into a second working line. The hydrostatic
piston machine can therefore also be used for applications in which
hydraulic circuits which are independent of one another are to be
supplied.
[0009] The two power transmission groups of the hydrostatic piston
machine according to the invention with the features of Claim 2 are
independently adjusted. It is as a result possible, when the
hydrostatic piston machine is used as a hydraulic pump, to firstly
adjust the volumetric delivery through the first power transmission
group. An adjustment in the same direction is then likewise carried
out through the second power transmission groups, for example. An
independent delivery rate setting when delivering into two
hydraulic circuits is of particular advantage. In this case the
mutually independent adjustment of the two power transmission
groups also enables one group to be implemented with a constant
swept volume and, on the other hand, the second power transmission
group to be implemented so as to be adjustable. The first power
transmission group is in this respect again formed by a cylinder
drum unit as well as the cylinder recesses arranged at the latter
together with the first group of pistons. The second power
transmission group is accordingly formed by the second group of
pistons together with the second cylinder recesses of the second
cylinder drum unit. The adjustment takes place by changing the axis
of rotation of the respective cylinder drum unit. The axis of
rotation of the respective cylinder drum unit is in this respect
changed independently of the orientation of the axis of rotation of
the respective other cylinder drum unit. Although they can be
changed independently of one another, the axes of rotation of the
two cylinder drum units can be adjusted together, depending on the
application.
[0010] Advantageous developments of the hydrostatic piston machine
according to the invention are presented in the subclaims.
[0011] It is in particular of advantage, in order to individually
adjust the pivoting angle of the cylinder drum units, to provide a
respective swash plate which can be adjusted in two opposite
directions from a neutral position. As a result, when delivering
into at least two different hydraulic circuits, the delivery
direction can be reversed in the two hydraulic circuits. This
reversal of the delivery direction may also take place in a
mutually independent manner. In this respect the neutral position
does not necessarily have to coincide with a running surface of the
swash plates which is perpendicular to the driving shaft axis. A
small angle, which compensates for hydraulic losses, between the
normals to the surfaces of the swash plate and the driving shaft
may also define a neutral position.
[0012] It is also of advantage to set the swash plates by means of
an adjusting device which executes a linear actuating movement. A
slender construction of the entire unit can be obtained through an
actuating device with a linear actuating movement. It is in
particular easily possible to obtain a linear actuating movement of
this kind by means of an adjusting piston which is hydraulically
loaded. It is in this respect of particular advantage for the
linear actuating movement to be executed parallel to the driving
shaft axis. A linear actuating movement of this kind executed
parallel to the driving shaft axis enables the adjusting device to
be arranged parallel relative to the driving shaft axis.
[0013] The pressure medium supply and pressure medium removal to
and from the first and second cylinder chambers is preferably
effected through the swash plate. Pressure medium channels are made
in the swash plate for this purpose. The pressure medium channels
of the first and of the second swash plate, respectively,
preferably lead into a channel portion of a first and second
housing flange part, respectively. Hydrostatic relief of the swash
plate can also advantageously be effected through this arrangement.
For this purpose leakage fluid which escapes upon passing from the
pressure medium channels of the swash plates to the channel
portions of the first and second housing flange part, respectively,
is used to form a hydrodynamic mounting between the swash plates
and the corresponding first bearing surface of the first housing
flange part and the second corresponding bearing surface of the
second housing flange part, respectively. The first and the second
swash plate are therefore arranged such that they can pivot in a
sliding manner in the first housing flange part and second housing
flange part, respectively, and hydrostatically relieved by way of a
small leakage quantity of pressure medium. There is therefore no
need for a special pressure medium supply in order to lubricate the
mounting of the swash plates.
[0014] At least one of the working connections, which can be
connected via the pressure medium channels in the first and the
second swash plate, respectively, to the first cylinder chambers
and the second cylinder chambers, respectively, is formed at the
first housing flange part and the second housing flange part,
respectively. The connection is therefore routed to the outside
over a short path inside the hydrostatic piston machine. Each of
the working connections is connected to a feed valve unit, via
which not only is pressure medium post-fed, but which also has a
high pressure limiting valve for safeguarding the connected working
line.
[0015] It is also of advantage to provide a common feed pressure
channel in the first housing flange part, a further housing part
and the second housing flange part. The feed valve units are
supplied with the pressure medium which is to be post-delivered via
this common feed pressure channel. The common feed pressure channel
has the advantage of a central connection being sufficient to
post-deliver pressure medium for feeding by means of a fixed
displacement pump, for example. As a result of using just one
common connection, there is no need for additional sealing points,
and the expenditure for installing lines at the hydrostatic piston
machine is reduced.
[0016] A preferred embodiment of the hydrostatic piston machine
according to the invention is represented in the drawings and
illustrated in detail on the basis of the following description. In
the drawings:
[0017] FIG. 1 is a first perspective representation of a
hydrostatic piston machine according to the invention;
[0018] FIG. 2 is a second perspective representation with a partial
section through an adjusting device of the hydrostatic piston
machine according to the invention;
[0019] FIG. 3 is an external view of a hydrostatic piston machine
according to the invention;
[0020] FIG. 4 is a second external view of a hydrostatic piston
machine according to the invention with a partial section through
an adjusting device;
[0021] FIG. 5 is a further perspective representation of the piston
machine according to the invention;
[0022] FIG. 6 is a first schematic representation of a first
housing flange part in a perspective view;
[0023] FIG. 7 is a second schematic representation of the first
housing flange part;
[0024] FIG. 8 is a third schematic representation of a first
housing flange part of the hydrostatic piston machine according to
the invention; and
[0025] FIG. 9 is a fourth schematic representation of a hydrostatic
piston machine according to the invention.
[0026] A perspective representation of a hydrostatic piston machine
1 according to the invention is represented in FIG. 1. The
hydrostatic piston machine 1 has a housing which comprises a first
housing flange part 2 and a second housing flange part 3. The first
housing flange part 2 and the second housing flange part 3 are
arranged at two opposite sides at a substantially tubular further
housing part 4 and complete this to form a closed housing. A
driving shaft 5 is rotatably mounted in the housing of the
hydrostatic piston machine 1. A first bearing 6 is arranged in the
first housing flange part 2 and a second bearing 7 is arranged in
the second housing flange part 3 in order to rotatably mount the
driving shaft 5. The first bearing 6 and the second bearing 7 are
preferably constructed as rolling contact bearings.
[0027] In order to connect the first housing flange part 2 and the
second housing flange part 3 to the further housing part 4, the
individual parts of the housing are connected to one another by way
of screws 8.
[0028] A support plate 9 is connected to the driving shaft 5 in a
rotationally rigid manner. The support plate 9 is of disc-shaped
construction and arranged approximately centrally in the region of
the further housing part 4. A first group of pistons 10 extends out
from the support plate 9 in the direction of the first housing
flange part 2. The pistons 10, only one of which is given a
reference number for the sake of clarity, are arranged on a common
circumferential circle on the support plate 9. On their side which
is remote from the support plate 9 the pistons 9 engage in a
respective cylinder recess of a cylinder 11, these being arranged
on a drum plate 14. Together with the first drum plate 14 and the
first group of cylinders 11, the first group of pistons 10 forms a
first power transmission group.
[0029] A second group of pistons 12 is arranged at the surface of
the support plate 9 which is oriented in the opposite direction,
which pistons can likewise engage by way of their side which is
remote from the support plate 9 in cylinder recesses of a
corresponding group of cylinders 13 and also be staggered relative
to the pistons 11 of the first group 11. FIG. 1 shows the opposite
arrangement, in which a through-hole can be punched in the support
plate 9. The second group of cylinders 13 is arranged on a second
drum plate 15. A second power transmission group is therefore
formed on the opposite side of the support plate 9. The first group
of cylinders 11 is rigidly fixed to the first drum plate 14 and the
second group of cylinders 13 is rigidly fixed to the second drum
plate 15 solely in the axial direction, i.e. a lateral movement on
the respective drum plate 14 and 15 is possible. For this purpose
the cylinders 11 and 13 are fixed in the axial direction in a
manner which is not represented. However the cylinders 11 and 13,
respectively, can execute a sliding movement on the supporting
surface, which cannot be discerned, of the first drum plate 14 and
the supporting surface 15', which is visible in FIG. 1, of the
second drum plate 15, respectively. If the first drum plate 14 and
the second drum plate 15 are inclined relative to the driving shaft
5, the elliptical projection of the pistons 10 and 12 onto the
first supporting surface, which is not represented, of the first
support plate 14 and the second supporting surface 15' of the
second support plate 15 is therefore compensated when a rotational
movement is executed.
[0030] A spherical formation may also be provided instead of the
plane supporting surfaces and cylinder bottoms. The compensating
movement is then linked with a tilting movement of the cylinders
11, 13.
[0031] In order to incline the first drum plate 14 or the second
drum plate 15, the first drum plate 14 is supported at a first
running surface, which cannot be discerned in FIG. 1, of a first
swash plate 16. The second support plate 15 is accordingly
supported at a second running surface 18 of a second swash plate
17. The first swash plate 16 and the second swash plate 17 can be
set independently of one another in terms of their angle relative
to the driving shaft 5. The axes of rotation of the drum plates 14,
15 lying against the running surfaces and therefore all the
cylinder drum units are consequently fixed independently of one
another through the swash plates 16, 17. The first drum plate 14
and the second drum plate 15 are connected to the driving shaft 5
in a rotationally rigid manner, so that the side of the first drum
plate 14 which is remote from the first group of cylinders 11
rotates in a sliding manner on the running surface of the first
pivoting plate 16. The second drum plate 15 is connected to the
driving shaft 5 in a corresponding rotationally rigid manner and
rotates on the running surface 18 of the second swash plate 17.
[0032] The pistons 10 of the first and the pistons 12 of the second
group, respectively, execute a reciprocating movement in the first
cylinders 11 and the second cylinders 13, respectively, through the
angles, set by way of the first swash plate 19 and the second swash
plate 17, of the axes of rotation of the first drum plate 14 and
the second drum plate 15, respectively, relative to the driving
shaft 5.
[0033] In order to enable the pivoting angle of the first swash
plate 16 to be set, the first swash plate 16 is constructed as a
pivoting rocker and a sliding surface 19 is formed at the first
swash plate 16 on the side which is remote from the running surface
which is not represented. In a corresponding manner the second
swash plate 17 is constructed as a pivoting rocker and a second
sliding surface 20 is formed at the second swash plate 17 on the
side which is remote from the running surface 18 of the second
swash plate 17. The first sliding surface 19 and the second sliding
surface 20 form a sliding contact bearing with corresponding
bearing surfaces of the first housing flange part 2 and the second
housing flange part 3, respectively, as is yet to be described.
[0034] A central recess, which is preferably elliptical, is in each
case provided in the swash plates 16, 17 in the same way as in the
drum plates 14, 15 for the passage of the driving shaft 5.
[0035] In order to connect the first cylinder chambers to a first
hydraulic circuit, the first cylinder chambers are alternately
connected to a high pressure and low pressure connection. For this
purpose an opening is provided in the cylinders bottoms, supported
at the first drum plate 14, of the first cylinders 11 as well as in
the first drum plate 14 for each cylinder 11. These openings are
connected in succession to control openings arranged in the running
surface of the first swash plate 16 during a rotation of the first
drum plate 14 together with the first cylinders 11 on the running
surface of the first swash plate 16. The control openings are
mouths of pressure medium channels which are formed in the first
swash plate 16. The pressure medium channels therefore connect the
running surface of the first swash plate 16 to the first sliding
surface 19, which is oriented in the opposite direction, of the
first swash plate 16. The mouths of the pressure medium channels on
the side of the first sliding surface 19 are formed such that there
is a connection to the low pressure or high pressure connection of
the first housing flange part 2 irrespective of the pivoting angle
of the first swash plate 16 which is set in each case. In addition
to the standard-shaped control openings, notches or bores can be
made in the running surface of the first swash plate in order to
improve the reversing behaviour, for example in order to reduce
pulsations.
[0036] In a corresponding manner two pressure medium channels are
formed in the second swash plate 17, these forming control openings
on the side of the running surface 18. The pressure medium channels
likewise open at the second sliding surface 20, which is oriented
in the opposite direction, such that, with corresponding openings
which are formed in the second flange part 3, they form a permanent
connection, irrespective of the pivoting angle of the swash plate
17 which is set.
[0037] An adjusting device 21, which co-operates with the second
swash plate 17, is represented in FIG. 1. The adjusting device 21
preferably executes a linear actuating movement, which is described
subsequently with reference to FIG. 2. The adjusting device 21 is
arranged on the outside of the further housing part 4 and oriented
substantially parallel to the driving shaft 5. The adjusting device
21 which is oriented in parallel co-operates via a sliding block
and an actuating lever 47 with the second swash plate 17 and
adjusts the inclination of the running surface 18 relative to the
driving shaft 5 by means of a linear movement. The adjustment can
take place in both directions. The normal to the surface of the
running surface 18 coincides with the axis of the driving shaft 5
in a neutral position, for example. The second swash plate 17 can
be pivoted out of this neutral position in the direction of
positive as well as in the direction of negative angles. The
delivery direction of the second power transmission group can thus
be reversed.
[0038] The hydrostatic piston machine according to the invention is
intended for delivery into two separate hydraulic circuits. The
first cylinder drum unit together with the first piston 10 is in
this respect connected to a first hydraulic circuit via a first
working line connection 22 and a second working line connection 23.
The first working line connection 22 and the second working line
connection 23 are arranged in the first housing flange part 2 and
connect the control kidneys of the first swash plate 10 via a first
working line channel 24 and a second working line channel 25,
respectively, to working lines.
[0039] In a corresponding manner the control kidneys of the second
swash plate 17 are connected via a third working line connection 26
and a fourth working line connection 28 to a second hydraulic
circuit. The second hydraulic circuit is likewise formed as a
closed circuit, with a third working line channel 27 and a fourth
working line channel 29 being provided for pressure medium supply
in the second housing flange part 3. The third working line channel
27 and the fourth working line channel 29 connect the third working
line connection 26 and the fourth working line connection 28 via
the pressure medium channels provided in the second swash plate 17
to the respective control kidneys in the running surface 18 of the
second swash plate 17.
[0040] On account of the independent adjustment of the first swash
plate 16 and the second swash plate 17, which can both be pivoted
out of their respective neutral position in two opposite
directions, it is also possible to select the delivery directions
in the first hydraulic circuit and in the second hydraulic circuit
independently of one another. A further adjusting device, which is
arranged on the back, which cannot be discerned in FIG. 1, of the
hydrostatic piston machine 1 is provided to adjust the first swash
plate 16. The neutral position of the first swash plate 16, just
like that of the second swash plate 17, does not necessarily
correspond to the position in which the running surfaces of the
first swash plate 16 and the second swash plate 17 form a right
angle with the driving shaft 5. It is in particular also possible
for the neutral position of the first swash plate 16 to form a
different angle relative to the axis of the driving shaft 5 than
the neutral position of the second swash plate 17.
[0041] A common feed system is provided in order to post-deliver
pressure medium into the first hydraulic circuit and the second
hydraulic circuit as well as to safeguard the hydraulic circuits
with respect to high working pressures. The first working line
channel 24 is connected to a feed valve unit, which is not visible
in FIG. 1. The second working line channel 25 is accordingly
connected to a second feed valve unit 30. The first working line
channel 24 as well as the second working line channel 25 can be
connected via the first feed valve unit and the second feed valve
unit 30 to a first connecting channel 32. A respective non-return
valve, which opens in the direction of the working line connection
22 and 23, respectively, is provided in the feed valve units, with
a high pressure limiting valve being arranged parallel to this
non-return valve. In the event of a critically high pressure acting
in the closing direction of the non-return valve, the non-return
valve can be bypassed by means of the high pressure limiting valve,
thus relieving the corresponding working line in the direction of
the first connecting line 32.
[0042] In a corresponding manner the third working line channel 27
and the fourth working line channel 29 are connected via a third
and fourth feed valve unit 31, respectively, to a second connecting
channel 33. The first connecting channel 32 and the second
connecting channel 33 open at a feed pressure limiting valve 34,
via which the first connecting channel 32 and the second connecting
channel 33 can be relieved into a tank volume if a certain feed
pressure fixed by a spring is exceeded. The tank volume may, for
example, be identical to the internal housing volume of the
hydrostatic piston machine 1, in which case the pressure medium
collected in the internal tank volume of the hydrostatic piston
machine 1 is removed in a manner which is not represented via a
return line to a further, external tank volume.
[0043] A feed line connection 35 is provided in order to
post-deliver pressure medium, via which connection a feed pressure
which is generated by an auxiliary pump is supplied to the first
connecting channel 32 and the second connecting channel 33. The
auxiliary pump may, for example, be a fixed displacement pump with
through-drive which is arranged in the first or second housing
flange part 2, 3. The corresponding housing flange part 2, 3 has an
intake connection in order to enable pressure medium to be drawn in
from a tank volume. The connecting channel 32, 33 is formed in an
overlapping manner in the further housing part 4 as well as in the
first housing flange part 2 and the second housing flange part 3.
The feed line connection 35 as well as the feed pressure limiting
valve 34 are arranged in the further housing part 4 and jointly
take over the pressure limiting function in the feed system for the
feed valve units of the first housing flange part 2 as well as the
feed valve units of the second housing flange part 3.
[0044] Pressure medium is in each case post-fed on the low pressure
side through the feed valve units 30, 31 associated with the
working line channel 24, 25, 27 and 29, respectively, if the
pressure in the working line carrying the low pressure is below the
feed pressure.
[0045] A part-sectional representation of the hydrostatic piston
machine according to the invention of FIG. 1 is represented in FIG.
2. It can be seen in the section through the adjusting device 21
that a first stop 37 and a second stop 38 are formed at a guide rod
36. A first spring hanger 39 and a second spring hanger 40 are
arranged in a sliding manner on the guide rod 36 between the first
stop 37 and the second stop 38. A compression spring 41, which in
the represented embodiment is formed as a spiral spring, is
arranged between the first spring hanger 39 and the second spring
hanger 40. The first spring hanger 39 and the second spring hanger
40 are arranged so as to be displaceable with their outer
circumference in a recess of an adjusting piston 42.
[0046] A deflection of the adjusting piston 42 to the right is
represented in FIG. 2. A driving device is provided in the recess
of the adjusting piston 42, at which device the first spring hanger
39 is supported and therefore follows the movement of the adjusting
piston 42 to the right. The compression spring 31, which is
supported at the second spring hanger 38 at the second stop 38 of
the guide rod 36, is then compressed. If a movement takes place in
the opposite direction, the spring 41 is supported via the first
spring hanger 39 at the adjusting piston 42 until the first spring
hanger 39 is in contact with the stop 37. Further movement of the
adjusting piston 42 to the left causes the second spring retainer
40 to be driven via a driving device, which cannot be discerned in
FIG. 2, of the adjusting piston 42 to the left, so that the spring
41 is now compressed on account of the contact with the first stop
37 as well as the second driving device of the adjusting piston
42.
[0047] A first actuating pressure chamber 43 and a second actuating
pressure chamber 44 are provided in order to deflect the adjusting
piston 42 out of its rest position, which is defined by the spring
41. The actuating pressure chambers 43 and 44 are formed between an
outer circumference of the adjusting piston 42 and a housing
portion 4' of the adjusting device 21 which is formed at the
further housing part 4. In order to generate an axial hydraulic
force on the adjusting piston 40, a radially widened region is
formed at the adjusting piston 42, which region separates the two
actuating pressure chambers 43 and 44 from one another and forms in
each actuating pressure chamber 43, 44 a surface which can be
loaded by the actuating pressure. A sliding block 46, which
co-operates with the actuating lever 47, is formed at the adjusting
piston 42 at the end of the adjusting piston 42 which is remote
from the guide rod 36. The actuating lever 47 is rigidly connected
to the second swash plate 17, so that a linear movement of the
sliding block 46 gives rise to a rotational movement of the second
swash plate 17. In order to change the actuating pressures in the
actuating pressure chambers 43 and 44, which act in opposition, a
pilot valve, for example, is used in a manner which is known per
se, which valve is connected in a manner which is not represented
to the first actuating pressure chamber 43 and the second actuating
pressure chamber 44.
[0048] An external view of the hydrostatic piston machine 1
according to the invention is once again represented in FIG. 3. The
adjusting device 21 is arranged in a region of the further housing
part 4. Here the guide rod 36 projects out of a cover portion 48
which is preferably arranged at the first housing flange part 2.
The guide rod 36 is preferably fixed by way of a thread in the
cover portion 48, so that the axial position of the guide rod 36
and therefore the neutral position of the second swash plate 17 can
be set by rotating the guide rod 36. A lock nut 49 serves to fix
the axial position.
[0049] A partial section through a hydrostatic piston machine
according to the invention is once again shown in FIG. 4. It can be
seen here that a housing portion 4' for the adjusting device 21 is
formed in the further housing part 4, which is closed on both sides
by the first housing flange part 2 and the second housing flange
part 3. This housing portion 4' is closed on one side by a first
cover portion 48 and on the opposite side by a second cover portion
50 of the second housing flange part 3. The second cover portion 50
accommodates the region of the sliding block 46 and of the
actuating lever 47.
[0050] In the further view which is represented in FIG. 5 the two
further feed valve units 51 and 52 can be seen in addition to the
feed valve units 30, 31 which are already known from FIGS. 1 and 2.
Moreover, corresponding to the arrangement of the adjusting device
21 for the second swash plate 17, a further adjusting device 53 is
provided, this co-operating with the first swash plate 16 and being
arranged in a housing portion lying opposite the housing portion 4'
at the further housing part 4. The further adjusting device 53 for
the first swash plate 16 corresponds in its structure to the
described adjusting device 21. A cover portion 55 is provided at
the first housing flange part 2 in order to accommodate the sliding
block of the further adjusting device 53. The first connecting
channel 32 consists of a first portion 32a and a second portion 32b
which are formed in the further housing part 4 and the first
housing flange part 2, respectively. The second connecting channel
33 accordingly consists of a first portion 33a formed in the
further housing part 4 and a second portion 33b in the second
housing flange part 3. In order to post-deliver pressure medium
into the first working line channel 24 and the second working line
channel 25, respectively, the second portion 32b of the first
connecting channel 32 branches into a first channel portion 32' and
a second channel portion 32''.
[0051] The second portion 33b of the second connecting channel 33
accordingly branches into a third channel portion 33' and a fourth
channel portion 33''.
[0052] Here the branching of the first connecting channel 32 and
the second connecting channel 33, respectively, is formed in the
first housing flange part 2 and the second housing flange part 3,
respectively. This means that only one channel mouth has to be
sealed in each case upon passing from the further housing part 4 to
the first housing flange part 2 or the second housing flange part
3.
[0053] The first housing flange part 2 is represented in FIG. 6. It
can be seen that a bearing surface 60', 60'' is formed in the first
housing flange part 2, which surface corresponds to the curvature
of the first sliding surface of the first swash plate 16. The first
working line channel 24 and the second working line channel 25 open
in a first opening 24' and a second opening 25', respectively, in
the bearing surface 60', 60''. In this case the dimensions of the
first opening 24' and the second opening 25' are preferably
identical for a hydrostatic piston machine 1 with reversible
control. The first opening 24' and the second opening 25'
preferably extend along a portion of the bearing surface 60', 60''.
The leakage fluid arising upon passing from the mouths of the
pressure medium channels of the first swash plate 16 at the sliding
surface 19 to the first working line channel 24 and the second
working line channel 25, respectively, serves to form a lubricating
film on the bearing surface 60, 60'. The first swash plate 16,
which is rotatably mounted in the bearing surface 60', 60'', is
lubricated by the lubricating film on the bearing surface 60',
60''. Recessed regions 62a, 62b, 62c are formed next to the bearing
surfaces 60', 60'', which regions accommodate the leakage fluid and
provide hydrostatic relief. Lateral walls seal the recessed regions
62a, 62b, 62c with respect to the swash plate 16.
[0054] FIG. 7 shows a further representation of a first housing
flange part 1 in a slightly amended perspective. The formation of
the second housing flange part 3 corresponds to the first housing
flange part 2.
[0055] The first housing flange part 2 is represented in a turned
view in FIG. 8. It can be seen in this view that a cover portion 55
is formed at the first housing flange part 2, in which portion a
recess 61 is provided for accommodating the actuating lever 47 as
well as the sliding block 46 of the adjusting piston 42.
[0056] FIG. 9 shows a further representation of the first flange
part 2.
[0057] The invention is not tied to the represented embodiment. The
individual features which are shown in the represented embodiment
can in particular be combined with one another in any desired
way.
* * * * *