U.S. patent application number 14/753306 was filed with the patent office on 2015-10-22 for pump mechanism.
The applicant listed for this patent is BRAN+LUEBBE GMBH. Invention is credited to Dirk PETERSEN.
Application Number | 20150300331 14/753306 |
Document ID | / |
Family ID | 36915746 |
Filed Date | 2015-10-22 |
United States Patent
Application |
20150300331 |
Kind Code |
A1 |
PETERSEN; Dirk |
October 22, 2015 |
PUMP MECHANISM
Abstract
A pump mechanism includes a crankshaft defining a crankshaft
longitudinal axis therethrough; three cylinders arranged around the
crankshaft, each of the three cylinders defining a cylinder
longitudinal axis therethrough, each cylinder longitudinal axis
extending away from the crankshaft in a substantially radial
direction, adjacent cylinder longitudinal axes enclosing
predetermined angles (Wz) about the crankshaft longitudinal axis;
and a piston corresponding to each of the three cylinders. Each
crank has a predetermined angular offset (W.sub.K) relative to an
adjacent crank, and the predetermined angular offset (W.sub.K) is
selected in accordance with the predetermined angles (Wz), in such
a way that phase shifts between each piston and a sequentially
actuated piston during a rotation of the crankshaft are equally
large. A sum of the predetermined angles (Wz) between adjacent
cylinder longitudinal axes, over all of the cylinder longitudinal
axes, is less than or equal to 180 degrees.
Inventors: |
PETERSEN; Dirk;
(Travenbruck, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
BRAN+LUEBBE GMBH |
NORDERSTEDT |
|
DE |
|
|
Family ID: |
36915746 |
Appl. No.: |
14/753306 |
Filed: |
June 29, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11473053 |
Jun 23, 2006 |
9097249 |
|
|
14753306 |
|
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Current U.S.
Class: |
417/273 |
Current CPC
Class: |
F04B 1/0408 20130101;
F04B 1/0421 20130101; F04B 1/0404 20130101; F04B 1/0413 20130101;
F04B 53/006 20130101 |
International
Class: |
F04B 1/04 20060101
F04B001/04; F04B 53/00 20060101 F04B053/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 24, 2005 |
DE |
102005029481.2 |
Claims
1. A pump mechanism comprising: a crankshaft defining a crankshaft
longitudinal axis therethrough; three cylinders arranged around the
crankshaft, each of the three cylinders defining a cylinder
longitudinal axis therethrough, each cylinder longitudinal axis
extending away from the crankshaft in a substantially radial
direction relative to the crankshaft longitudinal axis, adjacent
cylinder longitudinal axes enclosing predetermined angles (Wz) in a
circumferential direction about the crankshaft longitudinal axis;
and a piston corresponding to each of the three cylinders, each
piston being functionally connected to the crankshaft via a
connecting rod, a first end of each connecting rod having a main
bearing mounted on a crank of the crankshaft, wherein each crank
has a predetermined angular offset (W.sub.K) relative to an
adjacent crank, and the predetermined angular offset (W.sub.K) is
selected in accordance with the predetermined angles (Wz), in such
a way that phase shifts between each piston and a sequentially
actuated piston during a rotation of the crankshaft are equally
large, and wherein a sum of the predetermined angles (Wz) between
adjacent cylinder longitudinal axes, over all of the cylinder
longitudinal axes, is less than or equal to 180 degrees, and
wherein the longitudinal axes of the three cylinders are offset in
height relative to one another in a direction along the crankshaft
longitudinal axis that corresponds to a thickness of the connecting
rod.
2. The pump mechanism according to claim 1, wherein each piston is
connected to a corresponding connecting rod via a crosshead.
3. The pump mechanism according to claim 1, wherein neighboring
connecting rods are mounted sequentially along a direction of the
crankshaft longitudinal axis such that the neighboring connecting
rods slide on one another without spatial separation along the
direction of the crankshaft longitudinal axis.
4. The pump mechanism according claim 1, wherein the cylinder
longitudinal axes of adjacent cylinders of the three cylinders
enclose an angle (Wz) of 45 degrees and the cylinder longitudinal
axes of two outer cylinders of the three cylinders along the
crankshaft longitudinal axis enclose an angle of 90 degrees.
5. The pump mechanism according to claim 1, wherein the crankshaft
is coupled to an external drive motor via a worm gear pair.
6. The pump mechanism according to claim 5, wherein the worm gear
pair drives the crankshaft, a longitudinal axis of the external
drive motor is perpendicular to the crankshaft longitudinal axis,
and a longitudinal axis of the external drive motor encloses an
angle of less than or equal to 135 degrees with the cylinder
longitudinal axis of a middle cylinder.
7. The pump mechanism according to claim 1, wherein at least one of
the connecting rods is linked to a crosshead outside a crosshead
center.
8. The pump mechanism according to claim 1, wherein at least one of
the pistons is linked to a crosshead outside a crosshead
center.
9. The pump mechanism according to claim 1, wherein the crankshaft
is assembled from at least two parts assembled along a longitudinal
length of the crankshaft, and the at least two parts are configured
for connection to one another in a formfitting way in an area of
the cranks.
10. The pump mechanism according to claim 1, wherein the crankshaft
has at least two crankshaft main bearings disposed on opposite
sides of the cranks along the crankshaft longitudinal axis.
11. The pump mechanism according to claim 1, wherein the pump
mechanism is installed in a housing, and wherein locations of the
three cylinders are fixed with respect to the housing.
12. The pump mechanism according to claim 11, wherein the housing
is manufactured in one part and is equipped with a closable opening
in each of a floor and a rear wall for mounting.
13. The pump mechanism according to claim 11, wherein crosshead
tracks and pump headholders are integrated in the housing and
volumes of individual pump head holders are connected to one
another.
14. The pump mechanism according to claim 13, wherein the crosshead
tracks are located at a same height.
15. The pump mechanism according to claim 14, wherein each
connecting rod is connected to different location of the crosshead
tracks based on a position of each connecting rod along the
crankshaft longitudinal axis.
16. The pump mechanism according to claim 1, wherein each piston is
functionally connected to a second end of a corresponding
connecting rod via a rotatable connection disposed at the second
end of the corresponding connecting rod, the second end of the
connecting rod being opposite the first end of the connecting
rod.
17. The pump mechanism according to claim 16, wherein each piston
is functionally connected to the crankshaft via a crosshead, and
the crosshead is functionally connected to the second end of the
corresponding connecting rod via the rotatable connection.
18. The pump mechanism according to claim 1, wherein the crankshaft
is coupled to an external drive motor via an external
transmission.
19. The pump mechanism according to claim 1, further comprising a
diaphragm pump head coupled to each cylinder of the three
cylinders.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a Continuation of U.S.
application Ser. No. 11/473,053, titled "Pump Gear," filed Jun. 23,
2006, which claims priority to German Patent Application No.
102005029481.2, filed Jun. 24, 2005, the entire disclosures of
which being hereby incorporated by reference.
TECHNICAL FIELD
[0002] The present invention relates to a pump mechanism having
multiple cylinders, whose axes are situated around a crankshaft to
enclose predetermined angles, and whose pistons are each
functionally connected to a connecting rod mounted on a crank on
the crankshaft.
BACKGROUND
[0003] Multiple cylinder pump mechanisms are used in process pumps
for delivering large delivery streams or at high pressures.
Usually, diaphragm pump heads are used as the pump heads in this
case. Since the diaphragms used therein are only capable of limited
deflection, diaphragm pump heads having very large diameters are
required for large delivery volumes. If such large diaphragm pump
heads are to be operated using a multiple cylinder mechanism, the
intervals of the pump head holders and/or the cylinders must
therefore also be large enough. In typical pump mechanisms, the
individual cylinders are typically situated in parallel and mounted
horizontally on a crankshaft which also lies horizontally. In this
case, a large cylinder interval in the connection area for the pump
heads also requires a large mounting interval on the crankshaft. In
the event of multiple cylinders and large pump heads, the
crankshaft must be designed correspondingly long. This in turn
requires special properties of the crankshaft, in particular in
regard to stability and flexural strength. High costs in production
and storage result due to this and due to the large amount of space
required. Efforts to develop high-performance pump mechanisms which
require less space have resulted from this.
[0004] A multiple cylinder diaphragm pump, in which the cylinder
pistons are mounted on a single eccentric on a crankshaft, is known
from German Utility Model DE G8521520.1 U1. The individual
cylinders are situated radially around the crankshaft in this case.
The crankshaft itself is accordingly comparatively short. In order
to achieve uniform superposition of the partial delivery streams of
the individual cylinders, the angles at which the cylinders stand
to one another are distributed uniformly around 360.degree.. The
radial arrangement of the cylinders is connected to significant
disadvantages, however. Firstly, the overall pump is thus
relatively protrusive, and the space required by the pump is still
unsatisfactory, in addition, the accessibility of the rear
cylinders is significantly restricted when the pump is installed.
Furthermore, the piping requires a special outlay.
[0005] From this background, it is the object of the present
invention to specify a pump mechanism which is especially compact
and has a short crankshaft while simultaneously having good
accessibility to the individual cylinders.
SUMMARY
[0006] The object is achieved by a pump mechanism having multiple
cylinders, whose axes are situated around a crankshaft enclosing
predetermined angles, and whose pistons are each linked to a
connecting rod mounted on a crank on a crankshaft, each connecting
rod being mounted on its own crank and the cranks having a
predetermined angular offset to one another. The angular offset of
these cranks is selected according to the present invention as a
function of the angle which the cylinder axes enclose in such a way
that the phase shifts between each two pistons of the cylinders
actuated in sequence during a rotation of the crankshaft are
equally large.
[0007] The angles which the cylinder axes enclose are to be viewed
in this case in projection on a plane perpendicular to the
longitudinal axis of the crankshaft. The cylinder axes actually do
not intersect, since the attack points of the connecting rods on
the particular cranks are offset along the longitudinal axis of the
crankshaft. In the projection, however, the cylinder axes intersect
in the crankshaft and extend therefrom radially. The angular
distribution between the cylinder axes may be selected nearly
arbitrarily around the crankshaft. Only the minimum angle between
two neighboring cylinder axes is predefined by the dimensions of
the cylinder and the pump heads to be attached. Both symmetric
arrangements having regular angular intervals of the cylinders and
also asymmetric arrangements are possible. The manifold
possibilities of the geometric arrangement offers the advantage
that the pump may be adapted to many different construction
conditions, for example, when it is to be integrated into a more
complex facility.
[0008] In order that the most uniform possible torque curve during
a rotation of the crankshaft is achieved in spite of an asymmetric
arrangement of the cylinders around the crankshaft, the angles at
which the cranks stand to one another are tailored to the angular
distribution of the cylinders. The cranks, on which the connecting
rods of the individual cylinders are mounted, must therefore be
offset to one another around the axis of the crankshaft by a
specific angle in each case. The angular offset between the cranks
is then selected so that the phase shifts between the work cycles
of two sequentially actuated pistons are each equally large. In a
three-cylinder mechanism, the phase difference between the work
cycles of two cylinders, independently of the spatial arrangement
of the cylinders, is thus 120.degree. in each case. In a
four-cylinder mechanism, the phase difference of two sequentially
actuated cylinders is 90.degree. in each case. In this way, it is
ensured that the partial delivery streams of the individual
cylinders are superimposed uniformly and pressure pulsations which
are too strong do not occur. A more uniform delivery stream using
arbitrary angles of the cylinder axes may thus be produced through
the angular offset of the cranks.
[0009] The pump mechanism according to the present invention is
especially suitable for the attachment of piston diaphragm pump
heads. For trouble-free operation of piston diaphragm pump heads,
horizontal piston axes having valve connections lying one on top of
another, which are oriented perpendicularly thereto, are preferred.
The crankshaft is thus expediently mounted standing vertically, the
cylinder axes pointing horizontally radially away therefrom.
[0010] The linkage of the pistons by the connecting rod is
preferably performed via a crosshead, which absorbs the transverse
components of the rotational movement of the connecting rods
originating from the crankshaft.
[0011] The cranks for the individual connecting rods and cylinders
are distributed along the longitudinal axis of the crankshaft. With
a vertically mounted crankshaft, this means that the connecting rod
main bearings, using which the connecting rods are each mounted on
their own crank, are offset in height to one another. Since the
connecting rods extend horizontally from the crankshaft in this
case, the outer connecting rod ends are also offset in height to
one another. In a preferred embodiment variation, this height
offset corresponds precisely to the thickness of the connecting
rods. The cranks lie so close to one another that the connecting
rods slide on one another without noticeable spatial separation. If
the connections of connecting rods to crosshead and crosshead to
cylinder pistons are central, a corresponding height offset of the
cylinder axes by one connecting rod thickness each results
therefrom. The cylinder axes then extend, strictly speaking, in a
fan shape or similarly to the steps of a spiral staircase from the
crankshaft.
[0012] The cylinders in the pump mechanism according to the present
invention are preferably situated so that the sum of the angles
enclosed by the cylinder axes is less than or equal to 180.degree..
The cylinder axes are thus not distributed around the crankshaft,
but rather project from the crankshaft only in a half space. This
means that there are preferably two outermost cylinders, whose axes
enclose an angle of less than 180.degree. of one another, or which
extend parallel in opposite directions from the crankshaft. For the
case that the pump mechanism has more than these two outermost
cylinders, they are distributed in a fan shape between the two
outermost cylinders, while no cylinder axes project into the second
half space. The asymmetrical cylinder distribution is taken into
consideration by the angular offset of the cranks, so that
nonetheless a uniform delivery stream occurs. When the pump is
installed in a facility, the restriction of the space for cylinder
connections to 180.degree. has the advantage that all cylinders are
accessible from one side for maintenance work, for example.
[0013] The pump mechanism according to the present invention
preferably has three cylinders. If the cylinder axes are
distributed on 180.degree., these cylinders may each be at an angle
of 90.degree. to one another.
[0014] In an especially preferred refinement, the three cylinder
axes are only distributed over an angular range of 90.degree.,
however, and the individual cylinders are then each at an angle of
45.degree. to one another. This arrangement allows an even more
compact embodiment of the pump. The accessibility from one side is
improved even further. Depending on the special requirements, for
example, arrangements at angles of 30.degree. and 60.degree. or
other angle combinations are also possible.
[0015] The pump mechanism may be driven using a worm gear pair or
an external geared motor which may be coupled directly to the
crankshaft. Therefore, the crankshaft has both a coupling for such
an external transmission and also a connection device for a worm
gear pair in a preferred refinement. If the pump mechanism is
enclosed by a housing, both drive possibilities are expediently
possible using the same basic variation of a housing. The worm gear
pair may be integrated in the housing, while the external
transmission may be mounted externally on the housing in an
extension of the crankshaft. The drive motor is then either mounted
laterally directly on the housing for the drive via the worm gear
pair, or adjoining the housing for drive via the external
transmission. A stroke frequency suitable for diaphragm pumps may
be generated using both types of drive. Such a frequency is
typically below 250 strokes per minute. The drive of the pump
mechanism via a worm gear pair has the advantage that multiple pump
mechanisms may be chained horizontally via a connection of the worm
shafts. A vertical chaining of multiple mechanisms is possible with
both types of drive. For this purpose, the crankshafts of multiple
pumps may be coupled to one another. In this case, it is possible
to position the pump heads on the same side or also
alternately.
[0016] In a preferred embodiment variation of the pump mechanism
having three cylinders, which enclose an angle of 90.degree.
overall, the crankshaft is driven via a worm gear pair. The drive
motor, whose axis is perpendicular to the crankshaft, of course, is
preferably mounted in such a way that its axis encloses an angle of
less than or equal to 135.degree. with the axis of the middle
cylinder. Cylinders and drive motor are then situated in a fan
shape around the crankshaft. If the worm engages on the crankshaft
in proximity to the cranks, the crankshaft may be implemented as
correspondingly short, and an especially compact flat construction
of the pump is possible.
[0017] In all above-mentioned embodiment variations, these
cylinders are each offset by one connecting rod thickness in the
direction of the longitudinal axis of the crankshaft and do not lie
in one plane. This may make increased complexity necessary during
connection of the pump, in the piping, for example. This
constructive disadvantage may be avoided in a preferred embodiment
if one or more connecting rods are bent in such a way that the
outer ends of all connecting rods facing away from the crankshaft
lie in one plane, while the other ends are mounted next to one
another and/or, with a vertical crankshaft, one on top of another
on the crankshaft, of course. For a three-cylinder pump, at least
two such bent connecting rods are necessary so that all connecting
rod ends facing away from the crankshaft may lie in one plane. In
another preferred variation, the height offset of the cylinder axes
is avoided in that either the connecting rods engage off center on
the crossheads or the crossheads engage off center on the pistons.
In this way, the crosshead tracks, or at least the cylinder heads,
may be brought into one plane. A combination of both cited measures
is also expedient.
[0018] For the mounting of the connecting rods on the crankshaft,
the crankshaft is preferably assembled from at least two parts
along its length. The division is expediently located in the area
of the cranks. The torque transmission is then ensured by a
formfitting shaft-hub connection. Possible embodiments are, inter
alia, a multi-tooth or polygonal profile or a feather key. A
dividable crankshaft allows the use of multiple identical
connecting rods, or at least connecting rods having identically
shaped closed main bearings, for all cylinders. Storage and
production costs may thus be lowered and/or kept low. For
three-cylinder or four-cylinder pump mechanisms, the crankshaft
must be assembled from at least two parts for this purpose. For a
larger number of cylinders, more parts are correspondingly
required.
[0019] If an undivided crankshaft is used for a pump mechanism
having at least three cylinders, at least one main bearing of the
connecting rod preferably has a divided bearing shell. In a
three-cylinder mechanism, the middle connecting rod main bearing is
then expediently implemented as divided. The mounting of more than
two connecting rods on an undivided crankshaft may also
alternatively be made possible through different diameters of the
connecting rod main bearings. In particular for pump mechanisms
having a larger number of cylinders, the combination of a divided
crankshaft with divided connecting rod main bearings or connecting
rod main bearings of different diameters may be advisable. The
crankshaft itself is preferably mounted in at least two main
bearings on its ends, on both sides of the cranks For this purpose,
both friction bearing and also roller bearing technology may be
used.
[0020] The pump mechanism is expediently installed in a housing.
The housing is preferably manufactured from one part and equipped
with a closable opening in each of the floor and the rear wall for
mounting. The inner workings of the pump, i.e., the single-part or
multipart crankshaft and the connecting rods, may be mounted
through these openings.
[0021] In a preferred refinement, the crosshead tracks of the
cylinders and the pump head holders are integrated in the housing.
The individual pump head holders may then be connected to one
another. This has the advantage that pressure differences in the
housing which arise due to the oscillating movements of the
crossheads and pistons may be compensated for even with sealed
housing openings, since the required air mass equalization may
occur between the cylinders. In addition, the housing volumes
connected to one another may be used as a reservoir for hydraulic
oil in special construction variations of diaphragm pump heads.
[0022] The object of the present invention is also achieved by a
pump having a pump mechanism according to the present invention.
Diaphragm pump heads are preferably connected to the pump head
holders of the cylinders.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] In the following, the present invention is explained in
greater detail on the basis of exemplary embodiments illustrated in
the drawing.
[0024] FIG. 1: schematically shows a pump mechanism having three
cylinders in angular distribution around the crankshaft
indicated;
[0025] FIG. 2: schematically shows a pump mechanism and vertical
crankshaft in horizontal section;
[0026] FIG. 3: schematically shows the pump mechanism from FIG. 2
in vertical section;
[0027] FIG. 4: schematically shows a crankshaft having cranks in
vertical section along the longitudinal axis of the crankshaft;
[0028] FIG. 5: schematically shows a crankshaft in a top view
having angular offset of the cranks indicated;
[0029] FIG. 6: schematically shows a three-cylinder pump mechanism
having symmetrical angular distribution of the cylinder axes and
installed diaphragm pump heads in a front view of the front side of
the middle cylinder;
[0030] FIG. 7: schematically shows a crankshaft having bent
connecting rods in section along the longitudinal axis of the
crankshaft;
[0031] FIG. 8: schematically shows a crankshaft having bent
connecting rods in a top view of the front side of the
crankshaft;
[0032] FIG. 9: schematically shows a vertical section through a
multiple cylinder pump mechanism having vertical crankshaft and
cylinders lying horizontally in one plane;
[0033] FIG. 10: schematically shows a detail view of the connection
of connecting rods to crosshead in three different positions;
[0034] FIG. 11: schematically shows a detail view of the connection
of crosshead to pistons in three different positions;
[0035] FIG. 12: schematically shows a vertical section through a
pump mechanism having vertical crankshaft and external transmission
and drive motor coupled directly to the crankshaft;
[0036] FIG. 13: schematically shows a dividable crankshaft in
vertical section through the longitudinal axis;
[0037] FIG. 14: schematically shows a pump mechanism having
crosshead tracks and pump head holders integrated in the housing in
horizontal section.
DETAILED DESCRIPTION
[0038] FIG. 1 shows a possible geometric arrangement of the pump
mechanism 10 according to the present invention having three
cylinders 11 seen from above. The cylinders 11 point horizontally
away radially from the vertically oriented crankshaft 12. They are
symmetrically situated in this embodiment and each enclose an angle
W.sub.Z with one another in the projection shown on a plane
perpendicular to the crankshaft 12. A pump mechanism 10 having the
same geometry is shown in greater detail in FIG. 2. The sectional
plane of the drawing runs through the connecting rod 15 mounted
uppermost.
[0039] The two other connecting rods 15 are mounted without spacing
directly below the uppermost connecting rod 15 on the crankshaft
12. The vertical crankshaft 12 is driven via a horizontal worm gear
pair 18 using a drive motor 19. The three connecting rods 15 are
each mounted on their own crank 14 on the crankshaft 12. On their
other end, facing away from the crankshaft 12, they are linked to a
crosshead 16. This converts the rotational movement of the
connecting rods 15 into a linear movement. This movement is
transmitted to a piston 13 via a piston rod. This in turn links the
diaphragms of the attached pump heads 22.
[0040] The same exemplary embodiment is shown in FIG. 3 in vertical
section. The connecting rods 15, which are mounted without spacing
one on top of another on the crankshaft 12, are visible here. The
crankshaft 12, having the cranks 14 lying directly one on top of
another, is shown once again in FIG. 4 in detail in a side view.
The cranks appear horizontally shifted in this view, but actually
they have an angular offset W.sub.K to one another, as may be seen
in FIG. 5 in the top view. This angular offset W.sub.K is tailored
to the angle between the cylinders W.sub.Z. In the symmetrical
embodiment variation having three cylinders shown in FIGS. 1 and 2,
the relationship W.sub.K=120.degree.-W.sub.Z applies, W.sub.K
identifying the angular offset of the cranks 14 and W.sub.Z
identifying the intermediate angle of the cylinders 11.
[0041] With identically shaped connecting rods and identical
attachment of the crosshead tracks 25, pistons 13, and pump heads
22, the pump heads 22 have a height offset b to one another, which
corresponds to the thickness of the connecting rods. FIG. 6 shows
this height offset in an embodiment variation as shown in FIGS. 1
and 2 from the viewpoint of the middle pump head. This height
offset of the cylinders makes installation of the pump mechanism
according to the present invention more difficult and additionally
causes an increased space requirement in the vertical direction
unnecessarily. In order to avoid this disadvantage, one or more
connecting rods 15 may be designed as bent, so that the connecting
rod ends facing away from the crankshaft 12 all lie in one
horizontal plane.
[0042] FIG. 7 shows a vertical crankshaft 12 having three
connecting rods mounted thereon, the middle connecting rod being
implemented as straight and both the upper and the lower connecting
rod 15 being bent in such a way that the ends all lie on the plane
A-A of the middle connecting rod 15. In FIG. 8, this is shown once
again in a top view of the vertical crankshaft 12. The bends in the
two outer connecting rods are shown by lines 24.
[0043] Another possibility for compensating for the height offset b
is used in the refinements shown in FIGS. 9 through 11. FIG. 9
again shows a pump mechanism in vertical section. In the center, a
crosshead track 25 is shown in section and the opening to a
neighboring crosshead track is shown behind it in perspective. Both
crosshead tracks are located at the same height in spite of unbent
connecting rods 15 mounted one on top of another on the crankshaft
12. The height offset b is compensated for here in that the
connecting rods do not engage centrally on the crosshead, but
rather, depending on the position on the crankshaft, either below
or above the middle of the crosshead 16. The connecting rod 15
mounted lower on the lowermost crank 14 then also engages below the
middle on the crosshead 16. This is shown in detail in FIG. 10 on
the very left. The middle connecting rod 15, which engages in the
middle of the crosshead 16, is shown in the middle in FIG. 10. On
the right, the uppermost connecting rod 15 accordingly engages
above the middle on the crosshead 16.
[0044] FIG. 11 shows another embodiment variation in which the
crosshead tracks 25 also have a height offset. This is first
compensated for during the transmission of the movement to the
piston 13, in that this is accordingly linked above or below the
crosshead center.
[0045] The pump mechanism 10 may alternately be driven via a worm
gear pair 18 or via an external transmission 17 having a drive
motor 19 which may be coupled directly to the crankshaft 12. FIG.
12 shows a pump mechanism corresponding to the embodiment in FIGS.
2 and 3 in vertical section, but with an external transmission 17
here. This is coupled to the upper end of the vertically mounted
crankshaft 12. The drive motor 19 adjoins thereon.
[0046] In order that more than two identical connecting rods 15 may
be mounted on the crankshaft 12, the crankshaft 12 is implemented
as dividable in a special embodiment. FIG. 13 shows such a
crankshaft 12 in longitudinal section. The division is in the area
of the cranks 14. The crankshaft 12 shown is assembled from three
parts 12.1, 12.2, and 12.3.
[0047] FIG. 14 shows a compact pump mechanism 10 in a housing 20.
The individual crosshead tracks 25 are connected to one another via
housing openings 23. This embodiment variation has a symmetrical
angular distribution of the cylinders over 90.degree., as shown in
FIGS. 1 through 3. The drive motor is additionally situated at an
angle of 135.degree. in relation to the middle cylinder. This
special arrangement allows an especially compact embodiment of the
pump mechanism according to the present invention. Depending on the
size of the pump heads used, the angles between the cylinders and
the drive motor may also be selected as even smaller.
* * * * *