U.S. patent number 3,812,765 [Application Number 05/231,605] was granted by the patent office on 1974-05-28 for device for adjusting the stroke volume of hydraulic units.
This patent grant is currently assigned to Indramat-Gesellschaft Fuer Industrie Rationalisierung und. Invention is credited to Conrad R. Himmler.
United States Patent |
3,812,765 |
Himmler |
May 28, 1974 |
DEVICE FOR ADJUSTING THE STROKE VOLUME OF HYDRAULIC UNITS
Abstract
A control cylinder is operative for adjusting the stroke volume
of a hydraulic unit, and restoring means is provided for restoring
a piston in the control cylinder from a displaced control position
to a normal starting position. Servo-control means is associated
with the control cylinder and comprises fluid supply means for
supplying pressure fluid to the cylinder, control valve means
controlling the flow of such pressure fluid to the cylinder, and
throttling-gap regulating means operatively associated with the
control valve means and with the cylinder via the restoring means
for controlling the operation of the cylinder.
Inventors: |
Himmler; Conrad R. (Les
Essarts-Le-Roi, FR) |
Assignee: |
Indramat-Gesellschaft Fuer
Industrie Rationalisierung und (Lohr am Main,
DT)
|
Family
ID: |
26737151 |
Appl.
No.: |
05/231,605 |
Filed: |
March 3, 1972 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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58031 |
Jul 24, 1970 |
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Current U.S.
Class: |
91/387;
91/506 |
Current CPC
Class: |
F04B
49/06 (20130101); F16H 61/425 (20130101); F04B
49/002 (20130101); F16H 61/42 (20130101); F04B
1/324 (20130101) |
Current International
Class: |
F04B
1/32 (20060101); F04B 49/06 (20060101); F04B
1/12 (20060101); F16H 61/40 (20060101); F04B
49/00 (20060101); F16H 61/42 (20060101); F15b
013/16 () |
Field of
Search: |
;91/387,491,506 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Freeh; William L.
Attorney, Agent or Firm: Striker; Michael S.
Parent Case Text
This is a continuation, of application Ser. No. 58,031, filed July
24, 1970, now abandoned.
Claims
What is claimed as new and desired to be protected by Letters
Patent is set forth in the appended
1. A device for adjusting the stroke volume of hydraulic units,
comprising a hydraulic unit; a control cylinder operative for
adjusting the stroke volume of said unit; servo-control means for
said control cylinder, comprising fluid supply means for supplying
pressure fluid to said cylinder, and control valve means
controlling the flow of such pressure fluid to said cylinder;
throttling-gap regulating means operatively associated with said
control valve means and with said cylinder for controlling
operation of the latter, said throttling-gap regulating means
comprising a plate element mounted for displacement in response to
impingement of pressure fluid from one of two opposite directions;
and feedback detector means for detecting the displacement from a
normal starting position of a piston in said control cylinder, said
feedback detector means comprising an elastic member carried by
said plate element for displacement therewith, a lever pivotally
coupled with and displaceable by said piston and having a portion
provided with cam means, and cam-follower means cooperating with
said cam means and said elastic member for elastically deflecting
said elastic member in response to relative displacement of said
piston and plate element.
2. A device as defined in claim 1, said cam-follower means
comprising spring-biased pressure means urging and maintaining said
elastic member in tracking engagement with said cam means.
3. A device as defined in claim 1, said lever having an end portion
provided with a blind bore, and said piston having a piston rod
provided with a ball-shaped coupling portion which is matingly
received in said blind bore.
4. A device as defined in claim 1; further comprising an elongated
mounting member mounting said lever for pivotal movement about an
axis transversely to the elongation of said mounting member; and
displacing means for displacing said mounting member longitudinally
of itself.
5. A device as defined in claim 1, said control valve means being
hydraulically operated and in form of a cylindrical valve unit;
further comprising a housing section provided with a recess
accommodating said cylindrical valve unit, passage means for
passage of hydraulic fluid to and from said valve unit, said
throttling-gap regulating means being carried by said housing
section.
6. A device as defined in claim 5; and further comprising
electrically operated settling means for said throttling-gap
regulating means cooperating with the latter and also mounted on
said housing section.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a device for adjusting the stroke
volume of hydraulic units, and more particularly to a device for
continuously regulating the stroke volume of hydraulic pumps and
hydraulic motors via the use of a servo-control adjusting cylinder
with restoring means.
It is already known to effect continuous displacement of the
adjusting cylinder by positional changes of the restoring member
from the adjusting cylinder to the control valve. The positional
changes of the restoring member for the purpose of continuous
adjustment of the hydraulic pump or the hydraulic motor is usually
carried out manually and with these known devices a regulating of
the adjustment which can be programmed is not possible, because the
necessary short adjusting times and the accuracy of adjustment
cannot be obtained. This is particularly true when other values
which influence the stroke volume must be considered during the
adjustment, such as the pressure and the temperature of the system
or the rotational speed, for instance of a hydraulic motor.
SUMMARY OF THE INVENTION
It is, accordingly, an object of the present invention to provide a
device for the continuous adjustment of the stroke volume of
hydraulic pumps and hydraulic motors which constitutes an
improvement over what is known from the art.
More particularly it is an object of the invention to provide such
a device which, utilizing commercially available regulating units,
guarantees a high accuracy of adjustment and short adjusting times
such as they are especially required for programming of the
regulating function.
In pursuance of the above objects, and others which will become
apparent hereafter, one feature of the invention resides briefly
stated in a device for adjusting the stroke volume of hydraulic
units which comprises a hydraulic unit, a control cylinder
operative for adjusting the stroke volume of the unit, and
restoring means for restoring a piston in the control cylinder from
a displaced control position to a normal starting position.
Servo-control means is provided for the control cylinder and
comprises fluid supply means for supplying pressure fluid to the
cylinder, control valve means controlling the flow of such pressure
fluid to the cylinder, and throttling-gap regulating means
operatively associated with the control valve means and, via the
restoring means, with the cylinder for controlling operation of the
latter.
Through the use of a known and commercially available
throttling-gap regulating device which is operated by electrical
signals, as a part of the servo-control unit it is possible to
obtain quite readily --in a simple manner and with the least
possible technical expenditure--the provision of a regulating
function for the stroke volume of the hydraulic pump or motor,
which can be programmed. The magnitude of the electrical signal for
actuating of the throttling-gap regulating device is simultaneously
a measure for the adjustment of the adjusting or control
cylinder.
According to a further embodiment of the invention the restoring
device is constituted by an elastic member which is known per se
and secured to the impingement plate of the throttling-gap
regulating device, and by a cam track which is coupled with the
adjusting cylinder, with the elastic member and the cam track being
operatively associated. Advantageously, the cam track is provided
on a lever arm which is coupled with the adjusting cylinder and in
a simple manner the elastic member is maintained in tracking
abutment with the cam track by engagement with a pressure member
which is spring-biassed.
According to a further concept of the invention, permitting a still
further simplification of the restoring device, the cam track lever
coupled with the adjusting cylinder is provided in the region of
one end with a blind bore and a coupling portion on the piston rod
of the piston in the adjusting cylinder is matingly received in
this blind bore and has a generally ball-shaped configuration. For
setting the starting or center position of the adjusting cylinder
at an electrical signal of zero magnitude for the adjusting drive
of the throttling-gap regulating device, the member which mounts
the lever arm and constitutes the pivot axis for the same is itself
displaceable. To permit the construction of a compact control unit
the control valve which is operatively associated with the
throttling-gap regulating device and which is hydraulically
operated, is configurated as a cylindrical unit which is mounted in
a corresponding recess of a housing section which in turn is
secured to the adjusting cylinder and provided with bores for the
hydraulic fluid. At the same time this housing section carries the
throttling-gap regulating device with the electrically activatable
drive therefor.
According to still another embodiment of the invention the
electrical singals which activate the throttling-gap regulating
device are the output signals of a function generator to which the
rotational speed of the hydraulic motor or the hydraulic pump, the
temperature and the pressure in the hydraulic system are supplied
in form of electrical signals as variable dependent on the stroke
volume to be regulated, whereby a resulting signal is formed which
operates upon and controls the operation of the throttling-gap
regulating device.
The novel features which are considered as characteristic for the
invention are set forth in the following claims. The invention
itself, however, both as to its construction and its method of
operation, together with additional objects and advantages thereof,
will be best understood from the following description of specific
embodiments when read in connection with the accompanying
drawing.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a section through the housing of an adjustable
axial-piston pump in the region of the adjustable disc member;
FIG. 2 is a section through the adjusting cylinder and associated
components;
FIG. 3 is a section through the control valve of the embodiment of
FIGS. 1 and 2;
FIG. 4 is a section through the throttling-gap regulating device of
the illustrated embodiment;
FIG. 5 is a diagrammatic showing illustrating the construction of
the regulating device;
FIG. 6 illustrates in diagrammatic form the hydraulic system of the
disclosed embodiment;
FIG. 7 is a block diagram of the system shown in FIG. 6.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
It will be realized that FIGS. 1-7 illustrate a single exemplary
embodiment, but that this embodiment is indeed nothing more than
exemplary and that changes and modifications are possible and will
offer themselves readily to those skilled in the art. The
illustrated embodiment should therefore be considered nothing but
an exemplary vehicle for explanation of the invention.
Discussing now the drawing in detail, it will be seen that in FIG.
1 reference numeral 1 identifies the housing of a hydraulic pump or
a hydraulic motor, that is of a hydraulic unit in general. Mounting
pins or bolts 2 are provided at opposite sides of the housing 1 and
mount a disc member 3 for turning movement about an axis of
rotation 79. The disc member 3 constitutes the adjusting member for
the hydraulic pump or hydraulic motor, that is for the hereafter
referred-to hydraulic unit.
The disc member is provided with a bifurcated extension 4 to which
there is mounted by means of a bolt or pin 5 an extension 6 of the
piston rod 7 of an adjusting cylinder 8 which is more clearly shown
in FIG. 2. The mounting is such that the extension 4 and the
extension 6 are pivotable with reference to one another. The
cylinder body 9 of the cylinder unit 8 is accommodated in a bore 10
of the housing 1 as shown in FIG. 2, and the cylinder space 11 is
closed to the ambient atmosphere via a cover 12. A housing section
14 is secured to the portion 13 of the housing 1, and is intended
for accommodating the control valve 5 and the throttling-gap
regulating device 16 as well as the mount 17 for a lever 18.
As seen in FIGS. 1 and 2, the mount 17 includes a bolt member 19
with a bifurcated portion 20 in the recess 21 of which the lever 18
is pivotably mounted via a bolt 22. Two roller bearings 23 and 24
are mounted on the bolt 19 with a spacer sleeve 25 keeping them
axially spaced; a nut 26 prevents the bearings 23, 24 and the
spacer sleeve 25 from withdrawal from the bolt 19. The two outer
rings 23a, 24a--that is axially outer rings as seen with reference
to the axial elongation of the bolt 19--are axially guided in the
recesses 27 and 28 of the portion or section 14. A ring 30 abuts
against the shoulder 29 between the recesses 27 and 28 and in turn
dished springs 31 bear upon the ring 30 and constitute abutment
surfaces for the bearing 23. Through the provision of a threaded
sleeve 32, in conjunction with the springs 31, the bolt 19 with its
extension 20 is axially adjustable. The cap 33 protects the
threaded sleeve 32 against damage or unintentional or undesired
tampering.
FIG. 3 shows that the control valve 15 constitutes a unitary
construction and is provided with a cylindrical housing 34 which is
mounted in the bore 36 (see FIG. 2) of the housing section 14 by
means of a screw 35 or analogous means. Sealing rings 37 provide
for a fluid-tight seal with respect to the ambient surroundings. At
the end face 38 of the cover 39 of the valve a pressure spring 40
forming part of cam-follower means, abuts as shown in FIG. 2, and
urges a pressure member 41, forming another part of the
cam-follower means; in the direction of the cam track 42 provided
on the lever 18 and thus maintains the elastic member or extension
43a of the abutment plate 43 (see FIG. 4) of the throttling-gap
regulating device 16 in tracking engagement with the cam track 42.
The abutment or impingement plate 43 is located between the two
nozzles 44 and 45; at its upper end 46 it is connected to a tubular
body 47 which is fluid-tightly secured to the flange 48 at the
nozzle housing 49, a seal 50 providing for such fluid-tight
connection. The armature 51 of an electromagnet 52 is connected to
the tubular body 47, and the armature windings 53 surround the
armature 51. The tubular body 47 has a cross-sectional restriction
in its portion 47a of its axial extension, so that in effect it
acts in the manner of bourden tube. The nozzle spaces 54 and 55 are
connected with the spring-accommodating spaces 62 and 63 of the
control valve via bores 56, 57 provided in the nozzle housing,
bores 58 and 59 provided in the housing section 14, as well as
transverse bores 60, 61 in the housing 34 of the control valve 15.
The control space 64 of the control valve is connected via
transverse bores 65 in the housing 34 as well as via a
circumferential groove 66 and control bores 67 and 68 provided in
the housing section 14 and the portion 13 of the housing 1, with
the cylinder space 11. The cylinder space 69 of the adjusting or
control cylinder is connected directly via bores 70, 71 in the
housing portion 13 and the housing section 14 with the
non-illustrated source of pressure medium.
FIG. 5 shows the adjusting cylinder 8 in its starting position in
which its piston 72 is located midway between the ends of the
adjusting cylinder 8, so that it can be moved in either axial
direction by the same distance. In operation of the device, the
member 3 is positioned vertically in the housing 1 when the piston
72 is in the aforementioned position. This corresponds to a zero
stroke volume.
When an electrical signal is passed into the windings 53 of the
armature 51 of the magnet 52, the armature 51 is displaced by a
corresponding distance. This causes the abutment plate 43--which is
connected with the armature 51--to be similarly displaced in such a
manner that the distance between one of the nozzles and the plate
43 may for instance increase while the distance between the other
nozzle and the plate 43 is decreased by the corresponding distance.
Because the nozzle spaces are connected to a common source of
pressure medium P.sub.s =l via the filter 73 and the constant
throttles 74, a reduction in the distance between the nozzle and
the plate 43 results in an increase in the associated nozzle space
of the prevailing pressure, whereas the pressure decreases if the
distance increases.
If for instance the armature 51 is displaced in such a manner that
the distance between nozzle 44 and plate 43 decreases with a
corresponding increase in the distance between nozzle 45 and plate
43, then a higher pressure will prevail in the nozzle space 44 and
in the spring chamber 62 of the valve 15 which is connected with
the nozzle space 54 via the conduit portions L.sub.1, L.sub.11 than
in the nozzle space 55 and the pressure chamber of the control
valve 15 which is connected with the nozzle space 55 via the
conduit portion L.sub.2, L.sub.22. Because of the differential
pressure acting in the two spring chambers 62 and 63 the control
piston 75 of the control valve 15--which is in corresponding
connection with its opposite ends with these spaces 62 and
63--overcomes the spring 76 and moves in the direction of the
chamber 63, connecting via the edges 73 and the control space 64
which is in connection with the cylinder space 11, with the control
space 78 which in turn is in connection with the tank T. Because
the cylinder space 69 is subject to the pressure of the pressure
medium source P.sub.s, the piston 72 with piston rod 7 is displaced
in the direction of the cylinder space 11 and in so doing displaces
the member 3 about its pivot axis 79 through a corresponding
amount.
The displacement of the piston 72 continues until the restoring
arrangement--constituted by the lever 18 coupled with the piston
rod 7 and cooperating with the cam track 42 and the elastic member
43a of the plate 43--have restored the plate 43 in direction
oppositely the magnetic attraction of the throttling-gap regulating
device back to its zero position; this causes identity of pressure
in the nozzle spaces 54 and 55 and their associated spring chambers
62 and 63 of the valve 15, whereupon the control piston 75 is
returned to the illustrated zero position by the action of the
springs 82 and 76 and hydraulically blocks the cylinder space 11 of
the cylinder 8. Coupling of the lever 18 with the piston rod 7
takes place via a ball-shaped portion 81 of the bolt 5 which is
connected with the extension 6 of the piston rod 7, which portion
81 is matingly received in a blind bore 80 of the lever 18. The cam
track which causes the positional displacement of the elastic
member 43a of the plate 3, has such a configuration that its
distance to the pivot axis S of the lever 18 continuously decreases
from its one end 41a to its other end 41b.
The armature 51 is so magnetized--by a requisite electrical signal
centering into its windings 53--that a displacement of the plate 43
takes place in the direction of the nozzle 45 and thus causes an
increase of the pressure in the nozzle space 55 and the spring
chamber 63, then the piston 75 moves in the direction of the spring
chamber 62 and provides a connection between the pressure medium
source P.sub.s via the circumferential groove 84, the control space
64 as well as the control conduit 85, with the cylinder space 11 of
the adjusting cylinder 8. In view of the fact that the surface of
the piston 72 which is exposed in the cylinder space 11 and on
which pressure can be applied, is larger than the surface exposed
in the cylinder space 69, the piston 72 with its piston rod 7 in
this control position of the valve 15 affects movement in the
direction of the cylinder space 69. The piston 72 stops such
movement as soon as the plate member 43 is returned to its starting
position via the restoring device. The displacement distance of the
cylinder 8 depends, in addition to the magnitude of the electrical
signal for the adjusting drive of the throttling-gap regulating
device--which drive consists of the magnet and the armature with
its electrical windings--upon the elasticity of the elastic member
43a which cooperates with the blade 43, a lever ratio of the lever
18, and the configuration of the cam track 42. The starting or
center position of the cylinder 8 is adjusted--with an electrical
signal zero, that is with the drive of the throttling-gap
regulating device 16 de-energized--by corresponding displacement of
the lever axis S with the lever 18 via the threaded sleeve 32.
The hydraulic system illustrated in FIG. 6 consists essentially of
a regulating pump P which is driven at constant rotational speed,
and a hydraulic motor M. The setting of the stroke volume of the
pump P takes place via the adjusting cylinder Z which is activated
by the servo-valve V. The latter in turn is influenced by the
electrical adjusting drive E.
Conduits A and B connect the pump P with the motor M, and supply
conduits F with one-way valves R communicate with the conduits A
and B for maintaining the filling pressure. In the conduit F.sub.1
there is provided a flush valve SV, and in the conduits A and B
there are provided pressure-limiting valves DV. A filter Fi is
placed upstream of the servo-valve V.
There is further interposed an electrical temperature measuring
device Te and two electrical pressure measuring devices Dr.sub.1
and Dr.sub.2 in the conduits A and B connecting the pump P with the
motor M. The two devices Dr.sub.1 and Dr.sub.2 are provided
upstream and downstream of the motor M to determine the torque of
the latter. In addition a tachometer generater TG is coupled with
the shaft W of the motor M. to measure the actual number of
rotations of the motor. The thus-determined actual values of the
number of rotations n, as well as the torque DM determined from the
pressure differential upstream and downstream of the motor M, and
of the temperature Te of the pressure medium, are supplied to a
function generator FG shown in FIG. 7, whereinto the individual
nominal values and the relative dependencies of the same are
programmed. The control signal SE entering the function generator
FG is modified with these values before it is passed on to the
servo valve V, whereby in a very simple manner a predetermined
regulating program of the hydraulic system can be provided.
It will be understood that each of the elements described above, or
two or more together, may also find a useful application in other
types of constructions differing from the types described
above.
While the invention has been illustrated and described as embodied
in a device for adjusting the stroke volume of hydraulic units, it
is not intended to be limited to the details shown, since various
modifications and structural changes may be made without departing
in any way from the spirit of the present invention.
Without further analysis, the foregoing will so fully reveal the
gist of the present invention that others can by applying current
knowledge readily adapt it for various applications without
omitting features that, from the standpoint of prior art, fairly
constitute essential characteristics of the generic or specific
aspects of this invention and, therefore, such adaptations should
and are intended to be comprehended within the meaning and range of
equivalence of the following claims.
* * * * *