U.S. patent application number 11/081170 was filed with the patent office on 2005-09-29 for displacement pump with variable volume flow.
Invention is credited to Eisenmann, Siegfried A., Harle, Hermonn.
Application Number | 20050214149 11/081170 |
Document ID | / |
Family ID | 34813794 |
Filed Date | 2005-09-29 |
United States Patent
Application |
20050214149 |
Kind Code |
A1 |
Harle, Hermonn ; et
al. |
September 29, 2005 |
Displacement pump with variable volume flow
Abstract
A displacement pump with variable volume flow having a casing; a
chamber with an inlet opening on a low pressure side and an outlet
opening on a high pressure side for a fluid; an internal rotor
capable of rotation about a rotational axis (D.sub.I); a ring
having a central ring axis (D.sub.A) surrounding the internal rotor
and forming together with the ring, at least one delivery cell in
which fluid is delivered from a low pressure side to a high
pressure side of the pump; and an adjusting device which, during an
adjusting movement, rolls off on the casing without slipping is
provided. The internal rotor is fixed to the adjusting device and
rotatble about the rotational axis (D.sub.I), and the position of
the rotational axis (D.sub.I) relative to the central ring axis
(D.sub.A) of the ring is adjusted by the adjusting movement of the
adjusting device.
Inventors: |
Harle, Hermonn; (Aulendorf,
DE) ; Eisenmann, Siegfried A.; (Aulendorf,
DE) |
Correspondence
Address: |
RATNERPRESTIA
P O BOX 980
VALLEY FORGE
PA
19482-0980
US
|
Family ID: |
34813794 |
Appl. No.: |
11/081170 |
Filed: |
March 16, 2005 |
Current U.S.
Class: |
418/61.3 ;
418/204 |
Current CPC
Class: |
F04C 2/10 20130101; F04C
14/14 20130101 |
Class at
Publication: |
418/061.3 ;
418/204 |
International
Class: |
F01C 001/02; F01C
001/24; F01L 001/34; F01C 001/063 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 17, 2004 |
DE |
20 2004 004 231.2 |
Claims
What is claimed:
1. A displacement pump with variable volume flow, comprising: a.) a
casing; b.) a chamber defined by the casing and which comprises an
inlet opening on a low pressure side and an outlet opening on a
high pressure side for a fluid; c.) an internal rotor which is
accommodated in the chamber and can be rotated about a rotational
axis (D.sub.I); d.) a ring which is accommodated in the chamber,
has a central ring axis (D.sub.A), surrounds the internal rotor and
forms, together with the ring, in the case of rotary driving, at
least one delivery cell in which the fluid is delivered from the
low pressure side to the high pressure side; and e.) an adjusting
device which, during an adjusting movement, rolls off on the casing
without slipping, wherein i.) the internal rotor is fixed to the
adjusting device such that it can be rotated about the rotational
axis (D.sub.I), and wherein ii.) the position of the rotational
axis (D.sub.I) relative to the central ring axis (D.sub.A) of the
ring is adjusted by the adjusting movement of the adjusting
device.
2. The displacement pump as set forth in claim 1, wherein the
adjusting device comprises a toothing which is in toothed
engagement with a toothing of the casing during the adjusting
movement.
3. The displacement pump as set forth in claim 2, wherein the
toothing of the adjusting device is a round-flank toothing.
4. The displacement pump as set forth in claim 2, wherein a centre
point of a flank circle of a tooth of the adjusting device toothing
approximately describes a hypocycloid when rolling off on the
casing.
5. The displacement pump as set forth in claim 1, wherein the
adjusting device is an adjusting plate.
6. The displacement pump as set forth in claim 1, wherein the
adjusting device is arranged axially adjacent to the internal
rotor.
7. The displacement pump as set forth in claim 1, wherein the
adjusting device forms sealing stays to hydraulically partition the
high pressure side from the low pressure side.
8. The displacement pump as set forth in claim 5, wherein during
the adjusting movement, cylindrical surfaces which roll off on each
other are formed on the adjusting plate and on the casing.
9. The displacement pump as set forth in claim 5, wherein a
difference in the diameters of the casing and the adjusting plate,
underlying the cylindrical surfaces, is twice an eccentricity (e)
between the rotational axis (D.sub.I) of the internal rotor and the
ring axis (D.sub.A).
10. The displacement pump as set forth in claim 1, wherein at least
one of a magnitude and a rotational angular position of an
eccentricity (e) between the rotational axis (D.sub.I) of the
internal rotor and the central ring axis (D.sub.A) of the ring is
adjusted by the adjusting movement.
11. The displacement pump as set forth in claim 10, wherein the
magnitude of the eccentricity (e) is constant.
12. The displacement pump as set forth in claim 1, wherein the
adjusting device is adjusted by an adjusting force against the
force of an elastic component.
13. The displacement pump as set forth in claim 12, wherein the
adjusting force is formed from at least one of two hydraulic
adjusting forces which act on the adjusting device and the internal
rotor.
14. The displacement pump as set forth in claim 1 further
comprising an elasticity plane spanned by the rotational axis
(D.sub.I) and the ring axis (D.sub.A), wherein the elasticity plane
is rotated about the ring axis (D.sub.A) by a rotational angle
which is a multiple of the rotational angle of the adjusting device
arising as a result of rolling off.
15. The displacement pump as set forth in claim 1 further
comprising an amount of fluid delivered by the displacement pump
which increases roughly in proportion to a fluid pressure with
which the adjusting device is charged.
16. The displacement pump as set forth in claim 1, wherein a
pressure of the fluid of the high pressure side of the pump is
tapped at a location outside the displacement pump and the
adjusting device is charged with the pressure in order to vary the
volume flow.
17. The displacement pump as set forth in claim 16, wherein the
pressure is tapped at a crankshaft main gallery of a motor.
18. The displacement pump as set forth in claim 1, wherein the
displacement pump is at least one of an internal gear pump, a
pendulum slider pump, or a wing cell pump.
19. A displacement pump with variable volume flow, comprising: a.)
a pump casing; b.) a rotary-driven ring which is mounted in the
pump casing and comprises an internal toothing; c.) a rotatably
mounted internal rotor which meshes with the ring and comprises an
external toothing; d.) a gear ring running set comprising the ring
and the internal rotor, and having a difference in a number of
teeth equal to at least one, wherein the teeth have a tooth shape
with which a number of expanding and compressing delivery cells
sealed against each other, arise by contact of tips of the teeth;
e.) inlet and outlet openings arranged in the casing adjacent the
delivery cells which are partitioned from each other by sealing
stays; f.) wherein an angular position of an elasticity plane of
the gear ring running set with respect to the casing is varied; and
g.) an adjusting device including at least one of a pitch circle or
pitch circle segment which can be rolled off on at least one of a
pitch circle or pitch circle segment of the casing without
slipping, wherein i.) the adjusting device is arranged on one side
of the gear ring running set viewed axially, and ii.) the internal
rotor is fixed to the adjusting device such that it can be rotated
about a rotational axis (D.sub.I).
20. The displacement pump as set forth in claim 19, wherein a
difference between the adjusting device pitch circle diameter and
the casing pitch circle diameter is equal to twice an eccentricity
(e) of the gear ring running set.
21. The displacement pump as set forth in claim 19, wherein the
inlet and outlet openings are provided in the adjusting device and
are partitioned from each other by sealing stays which
substantially overlap with the inlet and outlet openings arranged
in the casing.
22. The displacement pump as set forth in claim 19, wherein the at
least one pitch circles or pitch circle segments which roll off on
each other without slipping are formed by pitch circles of an
adjusting transmission formed by at least one of a complete or
partial internal transmission.
23. The displacement pump as set forth in claim 22, wherein the
adjusting transmission has an eccentricity (e) which corresponds to
an eccentricity between the ring and the internal rotor.
24. The displacement pump as set forth in claim 22, wherein an
inner cylinder guide is provided on the casing and an outer
cylinder guide is provided on the adjusting device and the outer
cylinder guide rolls off on the inner cylinder guide during the
adjusting movement.
25. The displacement pump as set forth in claim 24, wherein each
cylinder guides have a constant radius of curvature, and a
difference between two radii of the curvature is equal to an
eccentricity (e) between the ring and the internal rotor.
26. The displacement pump as set forth in claim 19, further
comprising an internal transmission formed by an external toothing
of the adjusting device and an internal toothing of the casing,
wherein the internal toothing of the casing comprises at least one
of a partial toothing or one tooth more than the external toothing
of the adjusting device, and wherein a difference in the number of
teeth of at least the partial toothing is circumferential.
27. The displacement pump as set forth in claim 19, wherein the
internal toothing in the casing is manufactured by a
path-controlled HSC (high speed cutting) drill spindle.
28. The displacement pump as set forth in claim 1 further
comprising a slaving disc shrunk onto a shaft forming a fixed
rotational connection between a drive shaft of the pump and the
ring, and wherein the slaving disc comprises an external toothing
which is exactly fitted into the internal toothing of the ring,
forming an axial and allowing axial movement.
29. The displacement pump as set forth in claim 1 further
comprising a bearing journal of the internal rotor formed as a
hollow shaft, wherein a size of the inner diameter of the hollow
shaft is such that a drive shaft is connected rotationally fixedly
to the ring and freely rotates in the hollow shaft despite the
eccentric movement.
30. The displacement pump as set forth in claim 1 wherein a
magnitude of the adjusting movement of the adjusting device is
defined in accordance with the working pressure of the high
pressure side of the pump by the characteristic of a variable
spring.
31. The displacement pump as set forth in claim 30, wherein the
variable spring is formed as a screw pressure spring having a line
of application arranged at a distance from the moment pivots (M1,
M2) of the adjusting device to generate the moment pivots (M1,
M2).
32. The displacement pump as set forth in claim 1, wherein at least
one of the internal rotor, the ring, and the adjusting device is
manufactured in a powder metallurgical method.
33. The displacement pump as set forth in claim 28, wherein the
slave disk is rotationally and axially fixed by a gear shaft
spline.
34. The displacement pump as set forth in claim 19, wherein the
difference in the number of teeth is exactly equal to one.
Description
FIELD OF THE INVENTION
[0001] The invention relates to displacement pumps, in particular
internal-axle gear pumps, but also wing cell pumps or for example
also pendulum slider pumps, whose volume flow can be varied
according to requirement, i.e. can be adjusted. The pumps in
accordance with the invention are preferably used as lubricant oil
pumps for internal combustion engines, wherein the internal
combustion engine itself preferably drives the lubricant oil pump
in question. The internal combustion engine can in particular be a
drive motor, preferably a piston motor, of a vehicle. The specific
volume flow, i.e. the volume flow delivered per revolution of a
delivery wheel of the pump, can preferably be adjusted
continuously. The displacement pumps can also be advantageously
used as supply pumps for automatic transmissions in vehicles and
when used in this way are also preferably driven by the drive motor
of the vehicle in question. Although the displacement pump of the
invention, which can be adjusted according to requirement, is
suitable in particular for such applications, in which with
increasing drive speed, the fluid requirement increasingly falls
short of the delivery volume of pumps whose specific delivery
volume is constant, a pump in accordance with the invention can
also be advantageously employed in other situations, in which for
example the drive speed of the pump is constant and the fluid
requirement of the aggregate to be supplied fluctuates for other
reasons.
BACKGROUND OF THE INVENTION
[0002] Displacement pumps formed as gear ring pumps, such as the
invention also relates to in particular, are known from DE 297 03
369 U1 and EP 0 846 861 B1 which is based on it.
[0003] In the known variable pumps, the external rotor of the gear
ring running set is rotatably mounted in a variable ring which
surrounds the external rotor and rolls off without slipping in the
pump casing via an internal-external toothing, such that in
accordance with these kinematic ratios, the eccentric axis of the
gear ring running set rotates by up to 90.degree. relative to the
casing during the varying process. This enables a delivery amount
to be varied from a maximum to almost zero, with as small an
adjusting path as possible.
[0004] However, it has proven in practice that the design space
available in increasingly compact reciprocating piston motors is
becoming smaller and smaller. Since these pumps are preferably
arranged in the oil sump of the crankcases and since a mass-balance
shaft often also has to be additionally accommodated in this
region, together with other influencing factors such as conductor
frame fortification of the crankcase and a highly pitched oil pan
for ground clearance and the arrangement of the vehicle steering
parts, the outer diameter of the variable pump is too large. Since,
due to the heated idling at low motor speed, the pump has to
exhibit a specific minimum delivery amount, the diameter of the
gear ring running set cannot be arbitrarily reduced. Limits are
also set on enlarging the running set width, for reasons of space
and due to the suction limits of the teeth. Wide running sets have
the additional disadvantage that during speed regulation, the
overthrust losses between the converging and diverging teeth cells
caused by differential varying are very high.
SUMMARY OF THE INVENTION
[0005] It is therefore an object of the invention to provide a
displacement pump which exhibits smaller dimensions, with respect
to both the diameter and width of the running set, for the same
specific delivery amount.
[0006] The displacement pump with variable volume flow in
accordance with the invention comprises a casing and a chamber
which is formed in the casing and comprises an inlet opening on a
low pressure side and an outlet opening on a high pressure side for
a fluid. The pump can for example be an internal gear pump, a wing
cell pump or a pendulum slider pump. The pump further comprises an
internal rotor which is accommodated in the chamber and can be
rotated about a rotational axis, and a ring which is accommodated
in the chamber and has a central ring axis which surrounds the
internal rotor. In the case of rotary driving at least one of the
internal rotor and the ring, the ring and the internal rotor form
at least one delivery cell in which the fluid is delivered from the
low pressure side to the high pressure side. An adjusting device is
arranged such that during an adjusting movement, it rolls off on
the casing without slipping. In accordance with the invention, the
internal rotor is fixed to the adjusting device such that it can be
rotated about the rotational axis. Furthermore, the position of the
rotational axis relative to the ring axis of the ring can be
adjusted by the adjusting movement of the adjusting device.
[0007] By adjusting the internal rotor relative to the casing and
the surrounding ring in order to adjust the specific volume flow,
sealing the delivery space formed between the internal rotor and
the outer ring can be simplified.
[0008] If the pump is a gear ring pump, then the outer ring forms
an external rotor. In such embodiments, driving the gear ring
running set formed by the internal rotor and the external rotor via
the external rotor is facilitated. As compared to rotary driving
via the internal rotor, the pump speed in the case of rotary
driving via the external rotor is advantageously increased in
accordance with the ratio of the numbers of teeth of the internal
rotor and the external rotor, hence the diameter of the pump can be
reduced. The outer ring is also a rotor in a pendulum slider pump,
such as is for example described in FR 980 766. In a wing cell
pump, the outer ring can be fixed relative to the casing, or the
casing itself can form the internal cylindrical surface for a wing
wheel forming the internal rotor.
[0009] It is advantageous if an adjusting device which adjusts the
specific volume flow does not surround the internal rotor and the
outer ring but is arranged axially adjacent to them. It is
particularly advantageous if arranging the adjusting device
adjacent to the internal rotor and/or the outer ring is combined
with adjusting the specific volume flow by adjusting the internal
rotor. The adjusting device preferably rotationally mounts the
internal rotor such that it slaves the internal rotor during its
own adjusting movement by being fixedly connected to the internal
rotor with respect to the adjusting movement. The adjusting device
can for example comprise a toothing which is in toothed engagement
with a toothing of the casing during an adjusting movement. The
toothing of the adjusting device is preferably a round-flank
toothing. A centre point of a flank circle of a tooth of the
toothing of the adjusting device can for example approximately
describe a hypocycloid when rolling off on the casing.
[0010] By omitting the variable ring around the external rotor and
by increasing the speed of the internal rotor in proportion to the
numbers of teeth from the external rotor to the internal rotor as
compared to the drive speed, the design space of the variable pump
required is reduced superproportionally, for the same specific
delivery amount.
[0011] Such a variable pump in accordance with the invention is
thus also suitable for small-volume internal combustion engines, in
which particular value is placed on reducing the hydrostatic losses
and the circulated amount of oil at high speeds.
[0012] The compactness of a variable displacement pump in
accordance with the invention can hardly be surpassed. Since the
shaft bearings are rid of any hydrostatic load, and are only then
loaded by the traction rod of a continuously variable transmission
such as is preferably used for driving, the diameter of the shaft
can be reduced. The smaller effective running set width also
improves the suction capacity and reduces the danger of cavitation.
The volumetric efficiency is also improved due to the augmented
high-speed running. This is also due to the fact that the pinion
engagement between the external rotor and the internal rotor then
trails at the point of maximum toothed engagement, such that the
pressure side of the toothing is sealed better than the suction
side.
[0013] In accordance with preferred embodiments, the adjusting
device adjusts hydraulically by being charged with a fluid pressure
which is fed back from the high pressure side of the pump to the
adjusting device. The high pressure side of the pump reaches from
the high pressure side of the pump chamber to the point or points
of the aggregate or number of aggregates to be supplied, from which
the fluid, relieved of pressure, is fed back to a fluid reservoir.
It can also be advantageous to tap the fluid pressure of the high
pressure side of the pump at a location outside the displacement
pump and to charge the adjusting device with the pressure in order
to vary the volume flow. The pressure can for example be tapped at
a crankshaft main gallery of the motor.
[0014] In a preferred embodiment, the fluid pressure acting in the
pump chamber on the high pressure side, in combination with the
fluid pressure fed back to the adjusting device, generates the
adjusting force for adjusting. The adjusting force can for example
be formed from at least one of the two hydraulic adjusting forces
which act on the adjusting device and/or internal rotor. In
particular, the adjusting device can be adjusted by an adjusting
force against the force of an elastic component. The two adjusting
forces are advantageously superimposed positively on each other,
preferably by generating adjusting moments in the same direction.
In this way, it is possible to achieve a varying which reacts
particularly sensitively to changes in pressure. The invention thus
also relates to a displacement pump with variable volume flow,
comprising the features of the preamble of at least one of the
independent claims in combination with feeding the fluid pressure
back to the adjusting device and charging the adjusting device with
the fluid pressure fed back, in a direction such that the adjusting
force thus generated is superimposed positively on an adjusting
force generated by the fluid pressure of the high pressure side of
the pump chamber acting on one of the internal rotor and the outer
ring, the sum of the two forces being greater than each of the two
individual forces.
[0015] For the adjustability of the variable pump, such an
embodiment gives rise to the advantage that the hydraulic adjusting
forces of the internal rotor are added, over its bearing journal on
the one hand and those between the adjusting device--preferably
formed as an adjusting plate--and the casing, and not subtracted as
with the known displacement pump. This advantage is very important,
particularly for cold starts in which a quick adjustment to a zero
delivery amount is necessary in order to prevent damage to the oil
filter and oil conduits. Up until now, it has been necessary here
to provide an additional pressure control valve due to the inertia
of the adjustment to zero.
[0016] Although positively superimposing the two hydraulic
adjusting forces is particularly advantageous in its own right
alone, this embodiment is preferably combined with adjusting the
internal rotor or arranging the adjusting device axially adjacent
to the internal rotor and/or the outer ring, and particularly
preferably combined with both these features.
[0017] Due to the machinability of the internal toothing in the
casing for the adjusting transmission, the number of teeth here
cannot be selected to be arbitrarily large. A round-flank toothing
is most suitable on the adjusting plate, such that the internal
toothing in the casing--which preferably comprises one tooth more
than the external toothing of the adjusting plate--can be machined
using a rotating cutting tool (drill rod), as is known from the
known variable pump comprising a variable ring in FIG. 10 of EP 0
846 861 B1. The centre point of the flank circle of the tooth on
the adjusting plate describes a hypocycloid when rolling off in the
casing, although in practice the hypocycloid is not entirely free
of overlap. A radial elevation stroke therefore arises during
rolling off, such that the eccentricity of the variable plate in
the casing therefore fluctuates. The magnitude and/or the
rotational angular position of an eccentricity between the
rotational axis of the internal rotor and the central ring axis of
the ring can for example be adjusted by the adjusting movement. A
fluctuation in the eccentricity can, however, be undesirable in the
pump running set, since it leads to noise and wear on the pump
toothing. Guiding cylinders or cylinder segments which roll off on
each other are therefore preferably provided on the adjusting plate
and on the casing (in the drawings, on the pump casing in this
case), having diameters whose difference is equal to twice the
eccentricity of the pump running set, Therefore, the adjusting
plate does not roll off in the coarse systematic toothing but on
the two exactly machined circular cylinders. The difference in the
diameters of these guiding cylinders is equal to 2e with respect to
the variable plate and the casing, where e signifies the
eccentricity of the pump delivery set, preferably of the pump
running set, and of the toothings between the variable plate and
the casing. Thus, a radial elevation stroke while rolling the
variable plate off in the casing, and thus a fluctuation in the
eccentricity of the pump delivery set during the varying process,
is avoided. In particular, the magnitude of the eccentricity can be
constant.
[0018] No eccentric chucks are required for machining the casing
parts, since the shaft and external rotor bearings are concentric.
The depth of the internal toothing of the casing is minimised and
no longer has to be machined over the entire running set width, as
with the known design. This toothing can be high-precision
manufactured on a CNC machine with a C axis and path-controlled HSC
(high speed cutting) spindle unit in a clamp together with the
other machining operations. This results in a considerable
reduction in the expenditure of time for machining the toothing of
the casing.
[0019] The subject of the invention is shown in the drawings by way
of the example of a variable internal gear pump, arranged in the
oil sump, for a four-cylinder passenger car engine. This does not,
however, mean that the invention is restricted to such an
application. It could also, for example, be used in an automatic
transmission as an oil pressure pump for switching and for
supplying the transmission parts with oil. The variable pump would
then be positioned at the end of a continuous transmission input
shaft, such that in this case, the chain wheel shown in the
drawings is omitted, and instead the pump shaft is coupled,
concentrically and rotationally fixed, to the transmission input
shaft.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Example embodiments of the invention are explained below on
the basis of figures. Features disclosed by the example
embodiments, each individually and in any combination of features,
advantageously develop the subjects of the claims and also the
embodiments described above.
[0021] Specifically, there is shown:
[0022] FIG. 1 an axial section in accordance with the gradient A-A
in FIG. 2;
[0023] FIG. 2 a longitudinal section in accordance with the
intersection line E-E in FIG. 1;
[0024] FIG. 3 a longitudinal section in accordance with the
intersection line B-B in FIG. 1;
[0025] FIG. 4 a view of the variable plate, the variable spring and
the pump running set in the pump casing, with the cover (30)
removed, in the position in which the pump exhibits its maximum
possible delivery amount;
[0026] FIG. 5 the same view as in FIG. 4, but in the position in
which the pump exhibits its minimum possible delivery amount;
[0027] FIG. 6 a longitudinal section through the pump along the
intersection line D-D in FIG. 5; and
[0028] FIGS. 7 and 8 an illustrative representation of the variable
plate 13 together with its rolling off cylinder 25.
DETAILED DESCRIPTION OF THE INVENTION
[0029] For explaining the function in the individual figures, the
rotational direction of the running set shall be in the indicated
direction of the arrow 32, such that the respective suction and
pressure side in accordance with the expanding and compressing
delivery cells of the teeth is clearly provided. In the cover 30,
the suction support 31 is arranged on the suction side of the
running set, on which side the variable spring 28 can also be seen.
Thus, the spaces of the variable spring 28 and the rolling
cylinders 24 and 25, and the sections of the toothing shown on the
right of the image in FIGS. 4, 5, 6 and 7 between the variable
plate 13 and the casing 1 are under suction pressure, since the
variable plate 13 is fitted in between the cavern base 33 of the
casing and the casing-cover partition line, forming an axial seal
but able to move. The pressure space 35, which is hydraulically
connected to the compressing delivery cells of the gear ring
running set with the minimum possible choke (not shown in the
drawings), is thus sufficiently sealed against excessively high
volumetric losses with respect to the suction side. The delivery
cells of the gear ring running set are also sealed against each
other by a minimum axial clearance between the variable plate 13
and the slaving disc 26, such that here too, a clear hydraulic
partition between the high pressure side and the suction side is
provided. FIGS. 1 and 4 show the centre point of the internal rotor
in a position in which the pump exhibits its largest possible
delivery amount, since the eccentric axis E-E (in FIG. 1) of the
running set toothing coincides with the axis of symmetry of the
suction and pressure nodules in the casing and in the adjusting
plate 13. This position is always needed at low pump speeds, if the
oil viscosity is relatively low, i.e. when the motor is hot and in
particular during heated idling, in order that the oil consumers of
the motor are supplied with a sufficient amount of oil at a
sufficient oil pressure. The minimum pressure in the pressure
chamber 35 should not drop substantially below 1 bar, even when
bearing clearances of the motor parts have been enlarged by wear.
This maximum position is ensured by an exactly calculated bias on
the variable spring which holds the adjusting plate 13 fixed on a
stopper 36. The velocity pole for the rotational movement of the
variable plate thus lies at Ml in FIG. 4.
[0030] As the viscosity of the oil increases (e.g. during cold
starts) or as the speed of the pump increases, the system pressure
in the pressure chamber 35 and in the compressing delivery cells of
the gear ring running set increases. A sum of adjusting moments
arises around the velocity pole via the radial acting surfaces on
the internal rotor 4 and on the adjusting plate 13, such that the
variable spring 28 is no longer capable of holding the adjusting
plate 13 on the stopper 36. The variable system thus enters a poise
which is determined by the moment equilibrium between the sum of
the hydraulic adjusting moments and the moment of the variable
spring 28 about the velocity pole Ml. As the system pressure in the
pressure chamber 35 increases, the adjusting plate 13 rotates
clockwise in accordance with the representation in FIG. 4, wherein
the velocity pole Ml migrates on the reference circle of the
toothing of the casing towards the position M2 in FIG. 5.
Simultaneously, the centre point D.sub.I of the internal rotor 4
moves anti-clockwise out of the position P1 on its hollow shaft 16,
around the shaft centre point DA on an orbit having the radius e,
towards the position P2 in FIG. 5. Given the numbers of teeth of
the adjusting plate 13 and of the casing 1 provided (10:11 in the
drawings), the angular rotation of the internal rotor centre point
and thus of the eccentricity axis of the gear ring running set
anti-clockwise is ten times greater than the rotation of the
adjusting plate 13 clockwise about its own axis. As can be seen
from FIG. 5, a rotation of the adjusting plate 13 clockwise by just
9.degree. generates a rotation of the eccentricity axis e of the
gear ring running set anti-clockwise by 90.degree.. In this
90.degree. position in accordance with FIG. 5, the expanding and
compressing delivery cells in the gear running set have thus also
been rotated by 90.degree. with respect to the casing and thus with
respect to the reniform suction and pressure nodules, and even by
99.degree. with respect to the adjusting plate 13. This means that
a delivery amount of the pump is no longer possible. Within the
suction and pressure nodules, there then remains only an exchange
of liquid between the converging and diverging tooth chambers.
[0031] The position P2, i.e. a rotation by 90.degree. of the centre
point D.sub.I of the internal rotor 4 in accordance with FIG. 5, is
of course never assumed during normal motor operation, since as the
speed of the system as a whole increases, the motor bearings always
have a finite oil requirement which, however, does not remotely
increase in proportion to the speed, as opposed to the delivery
amount of a non-variable pump. The oil requirement of the motor
only increases roughly in proportion to the system pressure in the
pressure chamber 35, adapted to the flow resistance of all the oil
consumers, the viscosity of the oil and the degree of wear of the
shaft bearings of the motor. The poise of the variable system of
the adjusting pump in accordance with the invention is thus
automatically set, such that the delivery amount of the pump
exactly covers the oil requirement for the respective operational
state of the system as a whole. The designer then has the option of
adapting the adjusting pump to the motor by varying the bias and
the slope of the spring characteristic. Thus, a new pump does not
necessarily have to be designed for each engine size motor, as long
as the range in size varies within certain limits.
[0032] As already mentioned in the introductory part of the
description, it is expedient for the adjusting plate 13 not to roll
off on the reference circles of the toothings between the adjusting
plate 13 and the casing 1 but on two cylinder attachments, which
roll off on each other, on the adjusting plate and the casing. The
embodiment of the cylinder attachment on the adjusting plate is
shown somewhat more clearly in FIGS. 7 and 8. The cylinder
attachment 24 can also be seen on the left of the image in FIG.
3.
[0033] Latterly, attempts have been made to control the delivery
amount of the pump in accordance with the oil pressure in front of
the crankshaft bearings by providing one or more pressure sensors
in the main gallery of the crankshaft which tap the oil pressure
there and supply it to the pressure chamber 35 of the adjusting
pump. In this case, the pressure chamber 35 would then have to be
hydraulically partitioned from the main flow channel of the
pressure side of the pump.
* * * * *