U.S. patent application number 11/501271 was filed with the patent office on 2007-02-22 for linear compressor, particularly refrigerant compressor.
This patent application is currently assigned to Danfoss Compressors GmbH. Invention is credited to Poul Erik Hansen, Frank Holm Iversen, Klaus Reinwand, Jan Thomsen.
Application Number | 20070041853 11/501271 |
Document ID | / |
Family ID | 37770863 |
Filed Date | 2007-02-22 |
United States Patent
Application |
20070041853 |
Kind Code |
A1 |
Hansen; Poul Erik ; et
al. |
February 22, 2007 |
Linear compressor, particularly refrigerant compressor
Abstract
The invention concerns a linear compressor (1), particularly a
refrigerant compressor, with a first component group comprising a
stator (18, 20) of a linear motor (4) and a cylinder (8, 10), a
second component group comprising a reciprocating piston (16) and
an armature (22) of the linear motor (4) as well as a piston rod
(28) connecting the armature (22) to the piston (16), an oil sump
in a housing (2) and an oil pump (38), the second component group
being movable in relation to the first component group. It is
endeavoured to provide a simple design ensuring a lubrication of
the linear compressor. For this purpose, the oil pump (38) has a
pump housing (40) that is permanently connected to the piston rod
(28), the pump housing (40) immersing with at least one suction
opening (43; 43a, 43b) into the oil sump (41), the oil pump (38)
supplying oil to the inside of the piston rod (28).
Inventors: |
Hansen; Poul Erik; (Sydals,
DK) ; Reinwand; Klaus; (Harrislee, DE) ;
Thomsen; Jan; (Aabenraa, DK) ; Iversen; Frank
Holm; (Padborg, DK) |
Correspondence
Address: |
MCCORMICK, PAULDING & HUBER LLP
CITY PLACE II
185 ASYLUM STREET
HARTFORD
CT
06103
US
|
Assignee: |
Danfoss Compressors GmbH
Flensburg
DE
|
Family ID: |
37770863 |
Appl. No.: |
11/501271 |
Filed: |
August 9, 2006 |
Current U.S.
Class: |
417/417 |
Current CPC
Class: |
F04B 39/0292
20130101 |
Class at
Publication: |
417/417 |
International
Class: |
F04B 17/04 20060101
F04B017/04 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 17, 2005 |
DE |
10 2005 038 784.5 |
Claims
1. A linear compressor, particularly a refrigerant compressor, with
a first component group comprising a stator of a linear motor and a
cylinder, a second component group comprising a reciprocating
piston and an armature of the linear motor as well as a piston rod
connecting the armature to the piston, an oil sump in a housing and
an oil pump, the second component group being movable in relation
to the first component group, wherein the oil pump has a pump
housing that is permanently connected to the piston rod, the pump
housing immersing with at least one suction opening into the oil
sump, the oil pump supplying oil to the inside of the piston
rod.
2. The linear compressor according to claim 1, wherein the oil pump
is located at the end of the piston rod facing away from the
piston.
3. The linear compressor according to claim 1, wherein the piston
rod has a channel, which is connected to a piston joint.
4. The linear compressor according to claim 1, wherein the piston
rod is supplied with at least one pressure equalisation
opening.
5. The linear compressor according to claim 1, wherein the piston
rod has a connecting element to the piston, whose inner diameter
tapers.
6. The linear compressor according to claim 1, wherein at least one
inner diameter reduction is located inside the piston rod.
7. The linear compressor according to claim 6, wherein a recess is
located adjacent to the inner diameter reduction.
8. The linear compressor according to claim 1, wherein the piston
rod has a suction end, whose outer diameter reduces in a direction
away from the piston.
9. The linear compressor according to claim 8, wherein the suction
end has a suction channel, which ends inside the piston rod and has
a smaller inner diameter than the piston rod, the end of the
suction channel being surrounded by a projection pointing in the
direction of the piston.
10. The linear compressor according to claim 1, wherein the pump
housing has a pipe, whose one end is connected with the piston rod,
immersing together with the suction opening in the oil sump, the
normal to the surface of the suction opening having a component,
which is parallel to the movement direction of the first component
group.
11. The linear compressor according to claim 10, wherein the normal
to the surface is parallel to the movement direction.
12. The linear compressor according to claim 10, wherein the pump
housing has two suction openings in the oil sump, the normals to
the surfaces of the suction openings each having a component, which
is parallel to the movement direction of the first component group,
the components having opposite directions.
13. The linear compressor according to claim 12, wherein a blocking
element is located between the two suction openings, said blocking
element preventing a straight flow of oil from one suction opening
to the other.
14. The linear compressor according to claim 13, wherein the
blocking element is movable.
15. The linear compressor according to claim 14, wherein the
blocking element exists in the form of a valve element, which is
movable between a first valve seat that is allocated to one suction
opening and a second valve seat that is allocated to the other
suction opening.
16. The linear compressor according to claim 13, wherein each
suction opening is closed by a spring element, which can be opened
by the available oil pressure.
17. The linear compressor according to claim 16, wherein both
spring elements are formed by a common spring ring.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] Applicant hereby claims foreign priority benefits under
U.S.C. .sctn. 119 from German Patent Application No. 10 2005 038
784.5 filed on Aug. 17, 2005, the contents of which are
incorporated by reference herein. This Application relates to
German Patent Applications No. 10 2005 038 783.7 (Attorney Docket
No. 6495-0168); No. 10 2005 038 785.3 (Attorney Docket No.
6495-0170); No. 10 2005 038 781.0 (Attorney Docket No. 6495-0172);
No. 10 2005 038 780.2 (Attorney Docket No. 6495-0173), filed on the
same date herewith.
FIELD OF THE INVENTION
[0002] The invention concerns a linear compressor, particularly a
refrigerant compressor, with a first component group comprising a
stator of a linear motor and a cylinder, a second component group
comprising a reciprocating piston and an armature of the linear
motor as well as a piston rod connecting the armature to the
piston, an oil sump in a housing and an oil pump, the second
component group being movable in relation to the first component
group.
BACKGROUND OF THE INVENTION
[0003] With such a linear compressor, a corresponding electrical
supply of the stator will make the armature reciprocate in the
stator. The armature drives the piston in a likewise reciprocating
movement. The stator is connected to the cylinder, so that the
piston is moved in the cylinder, thus increasing and reducing a
compression volume.
[0004] During operation such a compressor must currently be
supplied with oil. The oil has two tasks. Firstly, it lubricates
parts, which move in relation to each other. Secondly, it helps
sealing a gap between the piston and the cylinder, so that the
compression behaviour of the compressor is improved.
[0005] U.S. Pat. No. 6,089,352 shows a linear compressor as
mentioned in the introduction. The oil pump is fixed on the stator.
It has an oblong chamber, whose first end is connected to an oil
sump and whose second end is connected to an oil reservoir
surrounding the cylinder. During operation, the stator oscillates
with the frequency, with which the piston moves in the cylinder.
Through inertia forces, which act upon the oil in the chamber
during this oscillating movement of the stator, the oil is
transported to the oil reservoir. However, it is necessary that the
chamber is filled from the beginning. An unfilled chamber cannot
work.
[0006] U.S. Pat. No. 5,993,175 shows a further linear compressor,
in which the oil pump is located in the stator. It has a pump
chamber, in which is located a displacement element that is
connected to the stator and the armature via springs. When the
armature moves in relative to the stator, the displacement element
starts oscillating and sucks oil via a suction pipe from the oil
sump into the pump chamber. From here, the oil can reach the
piston-cylinder-gap of the compressor via several openings. The
displacement element displaces excessive oil from the pump chamber
via an outlet opening.
[0007] US 2004/0052658 A1 shows a further linear compressor, in
which the stator is connected to an oil pump, which has a pump body
that is immersed in the oil sump. The pump body has an opening,
which extends perpendicularly to the movement direction of the
armature. During operation, the stator oscillates as a reaction to
the movement of the armature. Through the opening in the pump body
oil from the oil sump can enter, while the other end of the pump
body is connected via a pipe to an oil passage formed in the
stator, the oil passage ending in the gap between the piston and
the cylinder. In this connection, the cylinder is formed by the
inside of the stator and the piston is located in the stator.
[0008] Such oil pumps have a relatively low delivery rate.
[0009] JP 2000 154 778 A2 shows a linear compressor with an oil
pump. The oil pump has a pump chamber immersing in the oil sump,
the pump chamber being formed as a cylinder, in which a piston
moves. The piston is connected to the armature. During a stroke of
the armature in one direction, the piston displaces oil from the
pump chamber into an oil reservoir, which again supplies the gap
between the piston and the cylinder and a piston rod bearing with
oil. During a return stroke of the armature, the oil pump piston
sucks in oil through another opening. The path back from the oil
reservoir is blocked via a non-return valve. Such a pump supplies
an increased amount of lubricant. However, it is relatively
expensive to manufacture and requires a certain space inside the
compressor housing.
BRIEF SUMMARY OF THE INVENTION
[0010] The invention is based on the task of providing a simple
design to ensure lubrication for a linear compressor.
[0011] With a linear compressor as mentioned in the introduction,
this task is solved in that the oil pump has a pump housing that is
permanently connected to the piston rod, the pump housing immersing
with at least a suction opening into the oil sump, the oil pump
supplying oil to the inside of the piston rod.
[0012] The design of such an oil pump is relatively simple and only
requires little space. As the pump housing is permanently connected
to the piston rod, they reciprocate synchronously. The piston rod
has the same stroke as the piston, so that also the pump housing
with its suction opening will be moved through the oil sump via a
corresponding stroke. Thus, a sufficient amount of oil will reach
into the pump housing, the oil being supplied from here to the
inside of the piston rod. The piston rod is then used as auxiliary
means for transporting the oil to the area of piston and
cylinder.
[0013] It is preferred that the oil pump is located at the end of
the piston rod facing away from the piston. This embodiment has
several advantages. In a manner of speaking, the free end of the
piston rod facing away from the piston projects from the stator, so
that the pump housing is free to move. Design measures for
preventing a collision between the pump housing and other parts of
the linear compressor are not necessary. Secondly, the oil is
transported through the linear motor, and is thus able to dissipate
the heat occurring here. This will heat up the oil and reduce its
viscosity, so that it gets highly liquid. This again reduces
frictional losses between the piston and the cylinder.
[0014] Preferably, the piston rod has a channel, which is connected
to a piston joint. In order to equalise alignment errors, it may be
favourable not to locate the piston rigidly on the piston rod, but
via a joint, for example, a ball joint. In order to keep the
friction small here in spite of possibly occurring small movements,
the oil from the oil pump is supplied directly into this joint.
[0015] Preferably, the piston rod is supplied with at least one
pressure equalisation opening. The channel inside the piston rod
will usually not be completely filled with oil. On the contrary,
due to gravity the oil will only fill a partial area of the
cross-section. Over the oil a gas volume then remains, which is
connected to the inner chamber of the compressor housing via the
pressure equalisation opening. Thus, the pressure equalisation
opening permits a pressure equalisation, which is particularly
advantageous, when leakage gas is pushed backwards from the
compression chamber through the lubrication channels inside the
piston. An involved pressure build-up could counteract the supply
efficiency of the oil pump. This is reliably prevented by the
pressure equalisation opening.
[0016] Preferably, the piston rod has a connecting element to the
piston, whose inner diameter tapers. Thus, a steadily supplied
amount will increase the pressure, so that the oil can leave
towards the piston at a certain pressure.
[0017] It is also preferred that at least one inner diameter
reduction is located inside the piston rod. This inner diameter
reduction is then some kind of return flow prevention, the return
flow prevention managing without movable parts. Nevertheless,
within certain limits, it has the same effect as a non-return
valve.
[0018] This is further improved in that a recess is located
adjacent to the inner diameter reduction. A movement of the piston
rod in the direction of the cylinder will make the oil dam up in
this recess, as basically the oil film is inert and will not on its
own follow the movement of the piston rod. When the piston rod is
moved in the opposite direction, the inertia of the oil transported
through the inner diameter reduction and into the recess will cause
it to remain in the position, to which it has been transported, so
that subsequent movements of the piston rod over a short period
will transport the oil from the pump housing to the position, in
which it will evolve its effect.
[0019] Preferably, the piston rod has a suction end, whose outer
diameter reduces in a direction away from the piston. At least
section-wise, the suction end can also have a slightly conical
shape. This reduces the mass of the piston rod at this end. At the
same time, fixing the piston rod on the side facing away from the
piston will only require smaller surface. This is particularly
advantageous, when this end is fixed in a resonance spring
arrangement.
[0020] It is preferred that the suction end has a suction channel,
which ends inside the piston rod and has a smaller inner diameter
than the piston rod, the end of the suction channel being
surrounded by a projection pointing in the direction of the piston.
This causes that a relatively large oil volume is permanently
available inside the piston rod. At the same time, however, the
cross-section in the suction area is kept small, so that smaller
pressures are required to transport the oil from the oil sump to
the level of the piston rod.
[0021] Preferably, the pump housing has a pipe, whose one end is
connected with the piston rod, immersing together with the suction
opening in the oil sump, the normal to the surface of the suction
opening having a component, which is parallel to the movement
direction of the first component group. The normal to the surface
can also be called the axis of the suction opening. When the normal
to the surface or the axis is parallel to the movement direction of
the first component group, that is, has a component being parallel
to the movement direction of armature, piston rod and piston, the
movement of the suction opening will cause oil to be pressed into
the suction opening and then, via the pipe, into the inside of the
piston rod.
[0022] It is preferred that the normal to the surface is parallel
to the movement direction. In this case, the total cross-section of
the suction opening is available for the entry of the oil in the
movement direction of the piston rod.
[0023] In a preferred embodiment, it is ensured that the pump
housing has two suction openings in the oil sump, the normals to
the surfaces of the suction openings each having a component, which
is parallel to the movement direction of the first component group,
the components having opposite directions. In this case, a movement
of the piston rod in each direction will give an oil supply, that
is, oil will be supplied through the pump housing into the inside
of the piston rod in connection with both a suction stroke and a
pressure stroke of the piston.
[0024] It is preferred that a blocking element is located between
the two suction openings, said blocking element preventing a
straight flow of oil from one suction opening to the other. This
keeps losses small.
[0025] It is preferred that the blocking element is movable. The
movement can be initiated by the inertia of the blocking element or
by the pressure of the available lubricating oil or by both in
common. An additional energy supply or control of the blocking
element is thus not required.
[0026] It is preferred that the blocking element exists in the form
of a valve element, which is movable between a first valve seat
that is allocated to one suction opening and a second valve seat
that is allocated to the other suction opening. In this case, the
blocking element always blocks the suction opening, through which
oil is not presently pressed into the pump housing.
[0027] In an alternative embodiment it may be provided that each
suction opening is closed by a spring element, which can be opened
by the available oil pressure. Also in this case the passive
suction opening is closed, so that oil cannot escape from the pump
housing.
[0028] It is preferred that both spring elements are formed by a
common spring ring. This simplifies the mounting.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] In the following, the invention is described on the basis of
a preferred embodiment in connection with the drawings,
showing:
[0030] FIG. 1 is a schematic longitudinal section through a linear
compressor;
[0031] FIG. 2 is an enlarged view of a piston rod with piston and
oil pump;
[0032] FIG. 3 is a modified embodiment of an oil pump;
[0033] FIG. 4 is a longitudinal section through the oil pump
according to FIG. 3;
[0034] FIG. 5 is a third embodiment of an oil pump in a section V-V
according to FIG. 6;
[0035] FIG. 6 is a section VI-VI according to FIG. 5;
[0036] FIG. 7 is a fourth embodiment of an oil pump in a
perspective view; and
[0037] FIG. 8 is a sectional view for explaining an oil pump
according to FIG. 7.
DETAILED DESCRIPTION OF THE INVENTION
[0038] FIG. 1 shows a linear compressor 1, which is located in a
hermetically closed capsule 2.
[0039] The linear compressor 1 has a compression section 3, a drive
section 4 and a resonance spring arrangement 5. The unit formed by
the compression section 3, the drive section 4 and the resonance
spring arrangement 5 is suspended in the capsule 2 via two plane
annular springs 6, 7, each formed as a spiral with one winding. The
annular springs 6, 7 are fixed on the drive section 4.
[0040] The compression section 3 has a cylinder 8, whose one front
side is covered by a cylinder head 9. By means of a capsule 10, the
cylinder 8 and the cylinder body 9 are assembled in the form of a
cartridge. A suction muffler 11 and a pressure muffler 12 are fixed
on the cylinder head 9. The suction muffler 11 is connected with a
suction opening 13 and the pressure muffler is connected with a
pressure opening 14 in the cylinder head.
[0041] The capsule 10 is inserted in an intermediary ring 15, which
is connected with the drive section 4. During mounting, the capsule
10 and thus the cylinder 8 can be displaced within certain limits
in the axial direction of the cylinder relative to the intermediary
ring 15. When, as will be explained below, a predetermined position
of the cylinder in relation to the drive section 4 has been
reached, the capsule 10 is fixed in the intermediary ring 15, for
example by welding, soldering or gluing.
[0042] In the cylinder 8 is located a piston 16, which borders a
compression chamber 17 together with the cylinder 8 and the
cylinder head 9. Before fixing in the capsule 10 in the
intermediary ring 15, the piston is then expediently moved to its
upper dead point (in relation to FIG. 1: to the right) and the
cylinder 8 with the capsule 10 is displaced so that the compression
chamber 17 assumes a minimum size.
[0043] The drive section 4 has a linear motor. The linear motor has
an outer stator 18 with a recess 19 for a winding, not shown in
detail, and an inner stator 20. Between the outer stator 18 and the
inner stator 20 is an annular gap 21, in which an armature 22 is
movable. The armature carries permanent magnets 23, which are
connected with each other by means of two rings 24, 25. The rings
24, 25 can, for example, be made of plastic. The rings 24, 25 are
connected to inner rings 26, 27 via arms, not shown in detail,
which are guided through slots in the inner stator 20.
[0044] The inner rings 26, 27 are connected with a piston rod 28,
which again is connected with the piston 16. FIG. 2 shows an
enlargement of the piston rod with further details.
[0045] The outer stator 18 and the inner stator 20 are connected
with each other via motor covers 29, 30, which are tied to each
other by means of screw bolts 31. The screw bolts are guided in
parallel to the movement direction of the piston rod 28. The piston
rod 28 is guided through the motor covers 29, 30 in a touch-free
manner.
[0046] The intermediary ring 15 is connected with the cylinder side
motor cover 30, for example by welding, gluing or soldering.
[0047] The resonance spring arrangement 5, which is located at an
end of the drive section 4 opposite the compression section 3, has
a spring pack 32 comprising several plate springs 33. The spring
pack 32 is connected to the piston rod 28 in a central area 34. An
outer section 35 of the spring pack 32 is connected by means of
bolts 36 to a stop housing 37, which forms a stop for the spring
pack 32.
[0048] When the winding located in the recess 19 is provided with
current, the armature 22 moves in one direction and takes along the
piston rod 28 in this direction. When the direction of the current
is reversed, the armature 22 with the piston rod 28 moves in the
opposite direction and accordingly moves the piston 16 in the
opposite direction. This will periodically increase and decrease
the volume of the compression chamber 17. The resonance spring
arrangement 5 is adapted to the frequency of the current, so that
the movable part of the linear compressor 1, which is formed by the
armature 22, the piston rod 28, the piston 16, the oil pump
arrangement 38 and the movable part of the resonance spring
arrangement 5, oscillates in resonance.
[0049] At the end projecting from the spring pack 32, the piston
rod 28 is connected to an oil pump, which immerses in an oil sump
41, merely schematically shown in FIG. 2, which forms in the bottom
part of the capsule 2.
[0050] The oil pump 38 has a pump housing, which is immersed in the
oil sump 41. The pump housing 40 is connected to the piston rod 28
by means of a rigid pipe 42. This means that the pump housing 40
moves synchronously with the piston rod 28.
[0051] The pump housing 40 has a suction opening 43, whose normal
to the surface is parallel to the movement direction 44 of the
piston rod 28. In other words, the axis of the suction opening 43
is parallel to the movement direction 44 or the suction opening is
perpendicular to the movement direction 44. When the piston rod 28
is moved to the left, the oil from the oil sump 41 is pressed
through the suction opening 43 into the pipe 42, the movement of
the piston rod 28 transporting it into the hollow inside 45 of the
piston rod 28. The term "suction opening" is chosen for reasons of
clarity here, as the inlet opening of a pump is usually called
suction opening. In this case, however, the supply process of the
oil pump 38 is less based on suction and more on pressure.
[0052] At the piston side end, the channel 45 is connected to a
piston joint 46 in the form of a ball joint. The piston joint 46
has a ball 47, which is adopted in a ball socket 48. The contact
face between ball 47 and ball socket 48 can be lubricated with oil
supplied through the channel 45.
[0053] The connection between the piston rod 28 and the piston 16
occurs via a connecting element 49, which tapers conically in the
direction towards the piston 16. Thus, the inner diameter of the
channel 45 decreases. In the area of the piston 16 is provided a
pressure balancing opening 50. The channel 45 inside the piston rod
is usually not completely filled with oil, but only in the bottom
part. Through the lubricating channels in the piston 16 leakage gas
could also be pressed back from the compression chamber into the
channel 45. To prevent this leakage gas from building up a pressure
in the channel 45, which again would counteract the supply effect
of the oil pump, the pressure balancing opening 50 is provided for
generating a pressure balancing to the inside of the compressor
housing.
[0054] The connecting element 49 is attached on the piston rod 28.
It is fixed by frictional forces. If required, it can also be fixed
on the piston rod by gluing, welding or soldering. On a whole, it
is assumed that also the connecting element 49 is a part of the
piston rod 28.
[0055] The inside of the piston rod has at least one diameter
reduction 53. In the present embodiment, it is formed at the
transition between the piston rod and the connecting element 49.
Next to the diameter reduction is formed a recess 54. In the
present case, the recess is realised in the form of an insert 55,
which is inserted into the channel 45 and has an outlet cone 56 on
its piston side end.
[0056] The piston rod 28 has a suction end 57, whose outer diameter
reduces in a direction away from the piston 16. The suction end 57
can be screwed onto the piston rod 28 or be glued, welded or
soldered onto the piston rod 28. The diameter reduction of the
suction end 57 causes that less space is required for fixing the
piston rod 28 in the spring pack 32.
[0057] The suction end 57 has a suction channel 58, which has a
smaller inner diameter than the channel 45 of the piston rod 28.
The end of the suction channel 58 into the channel 45 is surrounded
by a projection 59, which points in the direction of the piston 16.
Radially outside the projection a recess 60 forms.
[0058] As shown schematically, a return flow prevention device 61
can also be located in the channel 45, for example in the form of a
saw tooth profile, whose piston side end has sides, which are
perpendicular or inclined towards the piston 16, whereas the other
sides have a smaller inclination. It is also possible to arrange
further "throttling spots" in the channel 45, which have
embodiments similar to those formed by the insert 55 or the
projection 59.
[0059] The oil supply through the unit consisting of piston rod 28
an oil pump arrangement 38 as shown in FIG. 2 can be described as
follows:
[0060] During operation, the armature 22 reciprocates together with
the piston 16 and the oil pump 38. The frequency of this movement
corresponds to the frequency of the a.c. supply to the linear
motor.
[0061] When the piston rod 28 is moved to the left (in relation to
the view in FIG. 2, oil from the oil sump 41 will be pressed into
the suction channel 58 through the suction opening 43 and the pipe
42. As the stroke length of the suction opening 43 corresponds to
the stroke length of the piston 16 in the cylinder 8, the supplied
amount of oil is sufficient to reach the suction channel 58. The
inertia of the oil causes that at least a share of the oil supplied
to the suction channel 58 remains there. Repeated movement strokes
of the piston rod 28 will thus eventually fill the suction channel
58, which runs over into the channel 45.
[0062] When the suction channel is filled and the oil runs into the
channel 45, the recess 60, which surrounds the projection 59, will
prevent it from completely flowing back into the suction channel
58. The inertia of the oil, which is pushed in the direction of the
cylinder 8 by the projection 59, will prevent it from flowing back
during a return movement of the piston rod 28. On the contrary, it
will eventually get through the insert 55 into connecting element
49. From here, it cannot either completely flow back into the
channel 45, as this is prevented by the outlet cone 56. The oil
available in the connecting element 49 can thus only flow on into
the ball joint 46. Additionally, the return flow of the oil can
also be prevented or blocked by the return flow prevention device
61.
[0063] The FIGS. 3 and 4 show a modified embodiment of the oil pump
arrangement 38. The same elements have the same reference numbers
as in FIGS. 1 and 2.
[0064] In this case, the pump housing 40 has two suction openings
43a, 43b, which are located opposite each other in the movement
direction 44. Between the two suction openings 43a, 43b is located
a stop element in the form of a wall 62, which prevents a straight
flow of oil from the suction opening 43a to the suction opening 43b
or vice versa.
[0065] In principle, this oil pump arrangement 38 works exactly as
explained in connection with FIG. 2. However, here an oil supply
occurs with each movement direction. When the pump housing 40 is
moved to the left, oil is pressed from the oil sump 41 through the
suction opening 43a into the pump housing 40. When the pump housing
40 is moved to the right, oil is pressed from the oil sump 41
through the suction opening 43b into the pump housing 40. Here, the
direction details refer to the view in FIG. 4.
[0066] The FIGS. 5 and 6 show a third embodiment of an oil pump
housing 40. Also this oil pump housing 40 has two suction openings
43a, 43b located opposite each other. The pump housing 40 has an
approximately circular inner cross-section. A spring plate 63 bent
into cylinder shape and covering both suction openings 43a, 43b is
inserted into this inner cross-section. The spring characteristic
of this spring plate 63 is relatively soft, so that already small
pressures will be sufficient to deform the spring plate 63 so much,
that one of the two suction openings 43a, 43b is released.
[0067] When the pump housing is moved to the left (in relation to
the view in FIG. 5), the oil available in the oil sump 41 will
press an arm 63a of the spring plate 63 into the inside of the pump
housing 40, and the oil can then flow past the arm 63a into the
inside of the pump housing 40. However, it cannot escape through
the oppositely located suction opening 43b, as the incoming oil
presses the other arm 63b firmly against the inner wall of the pump
housing 40 and closes the suction opening 43b. The same applies for
a movement of the pump housing 40 to the right. In this case, the
arm 63b is opened by the available oil and the arm 63a is kept
closed.
[0068] The FIGS. 7 and 8 show a fourth embodiment of a pump housing
40, which again has two suction openings 43a, 43b. The suction
opening 43a is allocated to a valve seat 64a and the suction
opening 43b is allocated to a valve seat 64b. A valve element 65,
here working as a blocking element, can move between the two valve
seats 64a, 64b. It therefore comes to rest on the first valve seat
64a or on the second valve seat 64b.
[0069] The movement of the valve element 65 is supported by two
factors. Firstly, the valve element 65 has a certain inertia, so
that a movement of the pump housing 40 to the right (in relation to
the view in FIG. 8) will bring it to the left valve seat 64a. This
movement is also supported by the oil flowing in through the
suction opening 43b. When, however, the pump housing 40 is moved to
the left, the valve element 65 is moved to the right in the pump
housing 40 and reaches the valve seat 64b. Oil from the oil sump 41
can thus only flow in through a suction opening 43a or 43b. An
escape through the other suction opening 43b, 43a is prevented.
[0070] While the present invention has been illustrated and
described with respect to a particular embodiment thereof, it
should be appreciated by those of ordinary skill in the art that
various modifications to this invention may be made without
departing from the spirit and scope of the present invention.
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