U.S. patent application number 12/992523 was filed with the patent office on 2011-05-26 for refrigerant compressor.
This patent application is currently assigned to ACC AUSTRIA GMBH. Invention is credited to Walter Brabek, Stefan Lamprecht, Alfred Schweighofer.
Application Number | 20110123373 12/992523 |
Document ID | / |
Family ID | 40907143 |
Filed Date | 2011-05-26 |
United States Patent
Application |
20110123373 |
Kind Code |
A1 |
Brabek; Walter ; et
al. |
May 26, 2011 |
REFRIGERANT COMPRESSOR
Abstract
Hermetically encapsulated refrigerant compressor (1), comprising
a cylinder housing (3), which is used as the basis for
manufacturing various refrigerant compressor construction series
each having different working volumes and a piston (6) guided in a
piston bore (8) of the cylinder housing (3) along a defined piston
run surface (9). According to the invention, it is provided that a
free run section (10) is situated in the piston bore (8) as a
function of the particular working volume to be implemented inside
the cylinder housing (3), which working volume is fixable by a
variation of the position of the piston (6) or the piston run
surface (9) in the piston bore (8), so that the piston run surface
(9) is reduced to a minimal guide length measured in the direction
of the cylinder axis (12), at which the piston (6) is only lowered
in its bottom dead center position far enough into the area of the
piston bore (8) corresponding to the piston run surface (9) so that
the piston (6) is just prevented from falling out of the piston
bore (8) and a sealing action of the piston (6) in relation to the
piston run surface (9) is provided.
Inventors: |
Brabek; Walter;
(Furstenfeld, AT) ; Schweighofer; Alfred;
(Grafendorf, AT) ; Lamprecht; Stefan; (St.
Anna/Aigen, AT) |
Assignee: |
ACC AUSTRIA GMBH
FURSTENFELD
AT
|
Family ID: |
40907143 |
Appl. No.: |
12/992523 |
Filed: |
May 13, 2009 |
PCT Filed: |
May 13, 2009 |
PCT NO: |
PCT/AT2009/000197 |
371 Date: |
February 9, 2011 |
Current U.S.
Class: |
417/410.1 |
Current CPC
Class: |
F04B 39/121 20130101;
F04B 39/122 20130101; F04B 2201/0206 20130101 |
Class at
Publication: |
417/410.1 |
International
Class: |
F04B 35/04 20060101
F04B035/04 |
Foreign Application Data
Date |
Code |
Application Number |
May 13, 2008 |
AT |
AT GM 275/2008 |
Claims
1. A hermetically encapsulated refrigerant compressor (1),
comprising a cylinder housing (3), which is used as the basis for
manufacturing various refrigerant compressor construction series
each having different sizes of the working volume, and a piston
(6), which is guided in a piston bore (8) of the cylinder housing
(3) along a defined piston run surface (9), for compressing a
working medium, which piston is linked using a connecting rod (7)
to a crankshaft (5) driven by an electric motor (13), the
crankshaft (5), which is rotatable around a rotational axis (11),
being mounted in a mounting body (2), and the piston bore (8) being
closed in a first end area (8a) by a cylinder head (15) comprising
a valve plate (16), while the piston bore (8) is open to
accommodate the piston (6) in a second end area (8b) facing toward
the crankshaft (5), the piston bore (8) having a free run section
(10) adjoining the piston run surface (9) and situated in the
second end area (8b) of the piston bore (8) facing toward the
crankshaft (5), whose clear open width (10') is greater than the
diameter (9') of the piston run surface (9), in order to prevent a
contact between piston (6) and cylinder housing (3) in this section
during the operating positions of the piston (6), wherein the free
run section (10) is situated, as a function of the particular
working volume to be implemented, within the cylinder housing (3),
which working volume is fixable by a variation of the position of
the piston (6) or the piston run surface (9) in the piston bore
(8), so that the piston run surface (9) is reduced to a minimal
guide length measured in the direction of the cylinder axis (12),
in the case of which the piston 6 is only lowered in its bottom
dead center position into the area of the piston bore 8
corresponding to the piston run surface (9), so that the piston (6)
is just prevented from falling out of the piston bore (8) and a
sealing action of the piston (6) in relation to the piston run
surface (9) is provided.
2. The hermetically encapsulated refrigerant compressor (1)
according to claim 1, wherein the variation of the position of the
piston (6) or the piston run surface (9) in the piston bore (8) is
performed via a use of connecting rods 7 and/or pistons 6
dimensioned in different lengths.
3. The hermetically encapsulated refrigerant compressor (1)
according to claim 1 wherein the variation of the position of the
piston (6) or the piston run surface (9) in the piston bore (8) is
performed by a variation of the eccentricity of a crank pin (19),
which links the connecting rod (7) on the crankshaft (3), in
relation to the rotational axis (11) of the crankshaft (3).
4. The hermetically encapsulated refrigerant compressor (1)
according to claim 1, wherein the free run section (10) is
implemented as a recess in the cylinder housing (3) which is
rotationally symmetric to the cylinder axis (12).
5. The hermetically encapsulated refrigerant compressor (1)
according to claim 1, wherein the clear cross-sectional width (10')
of the free run section (10) is greater by more than 1/100 mm,
preferably more than 1/10 mm, than the piston bore diameter
(8').
6. The hermetically encapsulated refrigerant compressor (1)
according to claim 1, wherein the piston run surface (9) merges
into the free run section (10) via a chamfer (38) or a radius
(39).
7. The hermetically encapsulated refrigerant compressor (1)
according to claim 1, wherein the cylinder housing (3) has a first
installation opening (24) running essentially perpendicularly to
the cylinder axis (12), the central axis (25) of this installation
opening (24) being situated offset by a distance amount (y) in the
direction of the first end area (8a) of the piston bore (8) to a
piston bolt axis (21) of a piston (6) located in its bottom dead
center position.
8. The hermetically encapsulated refrigerant compressor (1)
according to claim 1, wherein the free run section (10) is produced
by mechanical machining of the piston bore (8).
9. The hermetically encapsulated refrigerant compressor (1)
according to claim 1, wherein the mounting body (2) is implemented
integrally with the cylinder housing (3).
Description
AREA OF THE INVENTION
[0001] The invention relates to a hermetically encapsulated
refrigerant compressor, comprising a cylinder housing as the basis
for manufacturing various models of a refrigerant compressor family
and a piston, which is guided in a piston bore of the cylinder
housing along a defined piston run surface, for compressing a
working medium, which piston is linked using a connecting rod to a
crankshaft, which is driven by an electric motor, the crankshaft,
which is rotatable around a rotational axis, being mounted in a
mounting body which is preferably implemented integrally with the
cylinder housing, the piston bore being closed in a first end area
by a cylinder head comprising a valve plate, while the piston bore
is open in a second end area facing toward the crankshaft to
receive the piston, and the piston bore has a free run section,
which adjoins the piston run surface and is situated in the second
end area of the piston bore facing toward the crankshaft, whose
clear opening width is greater than the diameter of the piston run
surface, in order to prevent a contact between piston and cylinder
housing in this section during the operating positions of the
piston, according to the preamble of Claim 1.
PRIOR ART
[0002] The refrigerator process using zeotropic gases per se has
been known for some time. The refrigerant is heated in a vaporizer
by absorbing energy from the space to be cooled and finally
overheated, which results in vaporization, and is compressed to a
higher pressure level using a piston-cylinder unit of the
refrigerant compressor, where it discharges heat via a condenser
and is conveyed back into the vaporizer via a throttle, in which
pressure reduction and cooling of the refrigerant occur. Such
refrigerant compressors are used in the household and industrial
fields, where they are typically situated on the rear side of a
refrigerator or refrigerated shelf.
[0003] The refrigerant compressor, which has a hermetically sealed
compressor housing, comprises an electric motor, which drives a
piston oscillating in a piston bore of a cylinder housing via a
crankshaft to compress the refrigerant. It is typical to implement
the cylinder housing integrally in the form of a mounting body
which is fastenable on the stator of the electric motor, and which
also has a main bearing to accommodate the crankshaft.
Alternatively thereto, the cylinder housing can also be
manufactured as a separate part and can be fastened on the mounting
body.
[0004] The piston bore of the cylinder housing is closed in a first
axial end area by a valve plate or by a cylinder head, while the
piston bore is open to accommodate the piston or is penetrated by
the connecting rod in the installed state of the refrigerant
compressor in a second end area facing toward the crankshaft.
[0005] In order to reduce the friction of the piston during its
working strokes as much as possible, it is desirable for the piston
run surface, i.e., the surface formed by the piston bore on which
the piston contacts the cylinder housing or (because of the
required lubricant film) is guided by the cylinder housing with
slight play, to be kept as small as possible. The piston therefore
preferably protrudes out of the piston bore in its bottom dead
center position or the lateral surface of the piston only partially
contacts the piston run surface.
[0006] In the course of efficient mass production of refrigerant
compressors according to the species, the requirement exists that a
described cylinder housing or a mounting body having the cylinder
housing can be installed in a plurality of refrigerant compressor
production series, which differ from one another in design, in
particular with respect to the size of the working volume of the
piston-cylinder configuration.
[0007] To implement a working volume within the cylinder housing
which corresponds to the performance data of a particular
production series model, the cylinder housing or the crankshaft is
equipped with pistons and connecting rods of different sizes. The
piston plunges to different depths into the piston bore through a
specific selection of the piston and connecting rod lengths (each
measured along the cylinder axis).
[0008] According to the prior art, in this case the distance
between the rotational axis of the crankshaft and the beginning of
the piston run surface of the cylinder housing facing toward the
crankshaft remains unchanged, i.e., the second end area of the
piston bore is also not changed if connecting rods or pistons of
different lengths are used in the cylinder housing. In order to
perform a corresponding working space adaptation, in contrast, the
first end area of the piston bore facing toward the cylinder head
is shortened or the initially oversized cylinder housing is axially
shortened in the area intended for contact of the cylinder head or
the valve plate using a machining method, e.g., using milling.
[0009] After the cylinder housing or the piston bore has been
shortened in the first end area by an amount corresponding to the
particular desired working volume, the valve plate, including the
cylinder head, is fastened on the recently machined front side of
the cylinder housing.
[0010] In the case of special pre-installations of the cylinder
head and the valve plate on the cylinder housing, in particular in
the case of a screwless cylinder head fastening device known from
EP 1888918 A1, however, described machining or shortening of the
cylinder housing on the cylinder head side does not come into
consideration or would be viewed as uneconomical, since the
cylinder housing is provided with precisely manufactured fixing
grooves in this area, in which corresponding fixing elements engage
in a locking manner.
[0011] Alternatively to an adaptation of the axial length of the
cylinder housing or the piston bore, it would also be possible to
produce the particular desired working volume by an adaptation of
the piston bore diameter or the entire piston run surface provided
inside the cylinder housing. In such a case, the piston bore
diameter could be expanded by boring out and also a correspondingly
larger dimensioned piston or a piston having a larger piston
diameter could be inserted into the bored-out piston bore of the
cylinder housing. However, manufacturing of pistons having
diameters of different sizes, which is required in this case, is
complex and uneconomical. The precisely fitted final machining of
the bored-out piston bore in the area of the piston run surface
also requires a high manufacturing effort.
[0012] It is therefore the object of the present invention to
propose a simple possibility for implementing different working
volumes of a cylinder housing situated on a mounting body, without
the piston diameter having to be adapted to the required working
volume and without processing/shortening of the cylinder housing or
the piston bore on the cylinder head side having to be performed.
In this case, the friction of the piston on the piston guide
surface of the cylinder housing is to be reduced to a minimum and
the wear and the performance losses of refrigerant compressors
according to the species are thus to be reduced.
[0013] In particular, the cylinder housing or the mounting body is
to be able to be equipped with pistons and connecting rods of
different lengths, the piston run surface, i.e., the area of the
cylinder housing which the piston wipes during its working stroke,
being implemented as small as possible in each case.
[0014] It is a further object of the present invention to propose
an advantageous installation of a piston bolt which links the
piston to the connecting rod, in order to allow a plurality of
constructive design possibilities for implementing the
piston-cylinder configuration, in particular for dimensioning the
pistons, connecting rods, and crankshafts.
SUMMARY OF THE INVENTION
[0015] These objects are achieved according to the invention by a
hermetically encapsulated refrigerant compressor having the
characterizing features of Claim 1. A refrigerant compressor
according to the species of a refrigerant compressor construction
series comprises a cylinder housing and a piston guided in a
cylinder bore of the cylinder housing along a defined piston run
surface for compressing a working medium, which piston is linked
using a connecting rod to a crankshaft driven by a electric motor,
the crankshaft, which is rotatable around a rotational axis, being
mounted in a mounting body preferably implemented integrally with
the cylinder housing, and the piston bore being closed in the first
end area by a valve plate or a cylinder head, while the piston bore
is open to accommodate the piston in a second end area facing
toward the crankshaft and the piston bore has a free run section
adjoining the piston run surface situated in the second end area of
the piston bore facing toward the crankshaft, whose clear opening
width is greater than the diameter of the piston run surface, to
prevent contact between piston and cylinder housing in this section
during the operating positions of the piston or during the piston
oscillation.
[0016] It is provided according to the invention that the free run
section is situated as a function of a particular working volume,
which is delimited by the valve plate and the front side of the
piston, and which is fixable by a variation of the position of the
piston or the piston run surface in the piston bore, to be
implemented inside the cylinder housing in such a way that the
piston run surface is reduced in each case to a minimal guide
length, at which the piston is only lowered far enough in its
bottom dead center position into the area of the piston bore
corresponding to the piston run surface that the piston is just
prevented from falling out of the piston bore and a sealing action
of the piston in relation to the piston run surface is
provided.
[0017] A cylinder housing of the mounting body, which is produced
in a standard manner and is not yet defined or is oversized with
respect to its working volume, can therefore be used as the basis
for manufacturing various refrigerant compressor construction
series, which differ from one another in particular with respect to
the size of the working volume. The manufacturing costs of the
members of such refrigerant compressor construction series may
therefore be kept very economical.
[0018] The clear cross-section or the diameter measured
orthogonally to the cylinder axis is thus greater than the piston
bore diameter in the area of the piston run surface. In that the
piston run surface is reduced to a particular desired longitudinal
extension by providing the free run section according to the
invention, unnecessary friction of the piston on the cylinder
housing can be reduced and the effective performance of the
refrigerant compressor can thus be increased. The cylinder housing
or the mounting body can be equipped with pistons and connecting
rods of various lengths in this case, the piston run surface of the
cylinder housing wiped by the piston during its working strokes
being able to be optimized in a friction aspect, i.e., being able
to be kept as small as possible.
[0019] A further advantage of the invention is that joining of the
piston in the cylinder from the side of the cylinder facing toward
the crankshaft is made easier by the free run section having its
greater clear width in comparison to the diameter of the piston run
surface.
[0020] The transition between the free run section and the piston
run surface of the cylinder housing is implemented in a preferred
embodiment variation of the invention using a chamfer, a radius, or
a chamfer-radius combination, which in turn promotes the joining of
the piston and the sliding of the piston beyond the piston run
surface.
[0021] In a preferred embodiment variant of the invention, the free
run section is implemented, in a manner which is simple to
manufacture, as a recess in the cylinder housing which is
rotationally symmetric to the cylinder axis.
[0022] The design of the free run section in the cylinder housing
so that the piston run surface has a minimal guide length measured
in the direction of the cylinder axis or the axial direction of the
piston bore has the advantage that the piston, in its bottom dead
center position, is only lowered enough into the area of the piston
bore corresponding to the piston run surface so that the piston is
prevented from falling out of the piston bore and a sufficient
sealing action of the piston in relation to the piston run surface
is provided. The overlap area of the lateral surface of the piston
with the piston run surface of the cylinder housing viewed in the
bottom dead center position of the piston is thus selected as just
large enough that a reliable seal of the cylinder chamber bounded
by the front side of the piston and the valve plate is ensured,
while the piston partially protrudes beyond the crankshaft-side end
area of the piston run surface.
[0023] In that the piston run surface is reduced to a minimal guide
surface and the piston thus partially protrudes beyond the guide
surface, the advantage further results that a shorter connecting
rod can be used than in the case of completely lowering the piston,
which is located in its bottom dead center position, within the
piston run surface. A connecting rod whose length is selected as
short as possible allows a smaller overall size of the refrigerant
compressor. The space savings thus made possible within the
compressor housing can also be used for the purpose of enlarging
the rotor of the electric motor, which is connected to the
crankshaft, so that a higher torque of the crankshaft is
achievable.
[0024] A standard manufactured piston bore can be expanded by
mechanical machining in its second end area facing toward the
crankshaft depending on the usage requirement so that the guide
length is reduced to a particular possible minimum.
[0025] Such a variation of the position of the piston or the piston
run surface in the piston bore can be performed by a corresponding
adaptation of the geometry of the piston-cylinder configuration. In
a particularly preferred embodiment variant of the invention, the
position of the piston or the piston run surface is varied via a
use of connecting rods and/or pistons dimensioned in different
lengths (as a function of the particular desired working volume).
It is obvious that the length of the pistons and connecting rods is
measured in the oscillation direction of the piston in this
case.
[0026] The variation of the piston or the piston run surface in the
piston bore can also be performed by a variation of the
eccentricity of a crank pin, which links the connecting rod to the
crankshaft, in relation to the rotational axis of the
crankshaft.
[0027] In order to ensure that the piston does not contact the
cylinder housing in the free run section, it is provided according
to a preferred embodiment variant of the invention that the clear
cross-sectional width of the free run section is greater by more
than 2/100 mm, preferably by more than 1/10 mm, than the piston
bore diameter.
[0028] According to a further preferred embodiment variant of the
invention, it is provided that the cylinder housing has a first
installation opening running essentially perpendicularly to the
cylinder axis, the center axis of this installation opening being
situated offset by a distance amount in the direction of the first
end area of the piston bore to a piston bolt axis of a piston
located in its bottom dead center position. The first installation
opening is preferably used for the purpose of inserting a counter
holding tool into the piston bolt hole and thus determining the
location of the piston bolt within the piston bolt hole. The first
installation opening can also be used, however, to insert the
piston bolt itself into the piston bolt hole.
[0029] By installing the piston bolt in a piston located above its
bottom dead center position, greater design freedom is made
possible for the dimensioning of individual components of the
piston-cylinder configuration. In particular, connecting rods and
pistons of various lengths and differently dimensioned crankshafts
may be used, friction optimization of the piston run surface always
being able to be performed by the above-described provision
according to the invention of a free run section.
BRIEF DESCRIPTION OF THE FIGURES
[0030] The invention will be explained in greater detail on the
basis of an exemplary embodiment. In the figures:
[0031] FIG. 1 shows a sectional view of a refrigerant compressor
according to the invention
[0032] FIG. 2 shows an isometric detail view of a mounting body
according to the invention manufactured integrally with a cylinder
housing
[0033] FIG. 3 shows a vertical section through the mounting body
according to the invention from FIG. 2
[0034] FIG. 4 shows a top view of the mounting body according to
the invention from FIG. 2
[0035] FIG. 5 shows a bottom view of the mounting body according to
the invention from FIG. 2
[0036] FIG. 6 shows a side view of the mounting body according to
the invention from FIG. 2
[0037] FIG. 7 shows a mounting body having a comparatively large
working volume, a piston guided in a piston bore being located in
its bottom dead center position, in a top view
[0038] FIG. 8 shows a sectional view of the mounting body from FIG.
7 along line A-A
[0039] FIG. 9 shows a mounting body having a comparatively small
working volume, a piston guided in a piston bore being located in
its bottom dead center position, in a top view
[0040] FIG. 10 shows a sectional view of the mounting body from
FIG. 9 along line A-A
[0041] FIG. 11 shows a detail "A" from FIG. 10
DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS
[0042] A refrigerant compressor according to the invention having a
hermetically sealed compressor housing 14 is shown in FIG. 1. An
electric motor 13, which is mounted using a spring-loaded bearing
unit 27 in the floor area of the compressor housing 14, is situated
inside the compressor housing 14.
[0043] A bridge-shaped mounting body 2, which is fastened on the
stator 13a of the electric motor 13 using screw elements 29, is
placed on the electric motor 13. The mounting body 2 shown in a
detail view in FIG. 2 spans the upper part of a motor winding 34 of
the electric motor 13 (also referred to as the "upper winding
head") and has two diametrically opposing support base elements 31
and 32, which are supported on the stator 13a. Each of the support
base elements 31, 32 has two bearing pedestals 31a, 31b or 32a,
32b, respectively, at the ends, so that the relatively narrow
mounting body 2 thus rests stably on the stator 13a on a total of
four bearing surfaces (see a bottom view of the mounting body 2
according to FIG. 5).
[0044] Each support base element 31, 32 is provided with a threaded
hole 33. The stator 13a of the electric motor 13 is provided with
through holes 30, which run essentially vertically in the operating
position of the refrigerant compressor 1, through which screw
elements 29 can be guided and screwed into the threaded holes 33 of
the mounting body 2. Screw heads 29a of the screw elements 29
facing toward the floor area of the compressor housing 14 are
inserted into the spring-loaded bearing units 27, so that the
electric motor 13, including the mounting body 2 fastened thereon,
is held in a particular desired operating position.
[0045] The mounting body 2 is implemented integrally with a
cylinder housing 3, which is used to receive a piston 6 guided in a
piston bore 8 of the cylinder housing 3, using which a refrigerant,
which is conveyed into the compressor housing 14 and removed
therefrom again via supply and drain lines 35 in a known manner, is
compressed.
[0046] A main bearing 4 in the form of a plain bearing, which is
provided to receive a crankshaft 5, is implemented in a middle
section 2a of the mounting body 2 located between the support base
elements 31, 32. The rotational axis 11 of the crankshaft 5 or the
axis of symmetry of the bush-shaped main body runs orthogonally to
the cylinder axis 12 (see FIG. 3).
[0047] The shaft 5a of the crankshaft 5 is connected to a rotor 13b
and is set into rotation by a corresponding stator commutation, so
that the piston 6, which is linked using a connecting rod 7 to the
crankshaft 5, oscillates along the cylinder axis 12.
[0048] For this purpose, the connecting rod 7 has a first end
section provided with a first connecting rod eye 7a and a second
end section provided with a second connecting rod eye 7b, and a
shaft section 7c which connects the two end sections to one
another. The first connecting rod eye 7a is linked on a crank pin
19 of an eccentric cheek 18 of the crankshaft 5, while the second
connecting rod eye 7b is linked using a piston bolt 23 to the
piston 6.
[0049] The piston bore 8 of the cylinder housing is closed in a
first end area 8a by a valve plate 16, while the piston bore 8 is
open to accommodate the piston 6 or is penetrated by the connecting
rod 7 in a second end area 8b facing toward the crankshaft 5.
[0050] The piston 6 completes a particular defined piston stroke x
within the piston bore 8, the piston stroke x being understood as
the distance by which a front side 6a of the piston 6 facing toward
the valve plate 16 is displaced during a working stroke, i.e., a
movement from the bottom dead center position into the top dead
center position of the piston 6.
[0051] The valve plate 16 is fastened in the present exemplary
embodiment using a specially designed cylinder head 15 on the
cylinder housing 3. The cylinder head 15 and the valve plate 16 are
fastened without screws on the cylinder housing 3, the cylinder
head 15 being clamped using one or more clamp-shaped fixing
elements 17 on the cylinder housing 3 or being locked thereto. In
this case, the essentially cylindrical outer jacket of the cylinder
housing 3 is provided with a holding groove 26, which is obvious in
FIGS. 2 and 3, and in which the fixing element 17 engages.
[0052] Such a cylinder head configuration is pre-installed in mass
production and is no longer to be changed, in particular, the area
of the cylinder housing 3 on the cylinder head side is not to be
subsequently milled, as is typically performed for working volume
modification of the cylinder housing 3.
[0053] Independently of the selection of the length of the
connecting rod 7 and the length of the piston 6, which is measured
in the oscillation direction of the piston 6, i.e., independently
of how deep the piston 6 plunges into the piston bore 8 during its
working stroke, the friction of the piston 6 in the cylinder
housing 3 is to be reduced as much as possible. Such an
optimization of the friction behavior of the piston 6 is achieved
in that the piston run surface 9--this is the surface formed by the
piston bore 8 on which the piston 6 contacts the cylinder housing 3
or wipes it with slight play--is kept as small as possible, so that
the piston 6 partially protrudes out of the piston bore 8 or out of
the piston run surface 9 in its bottom dead center position, shown
in FIGS. 7 and 8. In FIG. 8, a piston 6 in its bottom dead center
position, is shown in a purely exemplary manner, whose lateral
surface is only enclosed approximately three-fourths by the
cylinder bore 8 or the piston run surface 9, while approximately
one-fourth of the piston lateral surface protrudes out of the
cylinder bore 8, i.e., is not guided by the cylinder housing 3.
[0054] There are multiple design possibilities to change the
working volume, which is delimited by the valve plate 16 (not shown
in FIG. 8) and the front side 6a of the piston 6, within the
cylinder housing 3. The working volume can be established as a
function of the characteristics of a particular refrigerant
compressor model via a variation of the position of the piston 6 or
the position of the piston run surface 9 in the piston bore 8.
[0055] The working volume or the position of the piston 6/the
piston run surface 9 is preferably changed by a variation of the
length of the connecting rod 7 or the connecting rod shaft 7c.
[0056] A change of the working volume or the position of the piston
6/the piston run surface 9 in the piston-cylinder configuration 28
shown in FIG. 8 may also be performed in that the geometry of the
crankshaft 5 is changed, for example, in that the eccentricity of
the crank pin 19 or the distance of the axis 20 of the crank pin
19, which is situated on the eccentric cheek 18, to the rotational
axis 11 of the crankshaft 6 is increased or decreased. In such a
case, the length of the piston stroke x would also change.
[0057] A change of the working volume or the position of the piston
6/the piston run surface 9 could also be performed by a
modification of the piston geometry or by a change of the piston
length (measured parallel to the cylinder axis 12).
[0058] Independently of the concrete component modifications by
which a change of the working volume is performed, the piston run
surface 9 of the cylinder bore 8 is also displaced or it is
shortened or lengthened similarly to the change of the working
volume.
[0059] Solely as an example, a piston-cylinder configuration 28 is
shown in FIG. 8 having a relatively large longitudinal extension z
of the working volume measured along the cylinder axis 12, while a
piston-cylinder configuration 28 having a relatively small working
volume longitudinal extension z measured along the cylinder axis 12
is shown in FIG. 10.
[0060] For example, if the longitudinal extension z of the working
volume of the piston-cylinder configuration 28 shown in FIG. 8 were
changed in such a manner that a longer connecting rod 7 was used
and also the distance of the axis 20 of the crank pin 19 situated
on the eccentric cheek 18 on the crankshaft 5 was also adapted to
the rotational axis 11 of the crankshaft 5, this would have the
result that the piston 6 would also plunge deeper into the piston
bore 8 during its bottom dead center position and the entire
lateral surface of the piston 6 would be enclosed by the piston
bore 8 in this case.
[0061] It is obvious that a modification or expansion of the
working volume provided inside the cylinder housing 3 can still
also be performed by a corresponding variation of the piston bore
diameter 8' or by boring out the piston bore 8.
[0062] As already described in the introduction, however, a contact
of the entire piston lateral surface by the cylinder housing 3
would be disadvantageous with respect to friction efficiency, since
it would suffice in the bottom dead center position of the piston 6
if the piston 6 were only lowered partially into the piston bore 8
of the cylinder housing 3.
[0063] It is provided according to the invention that the piston
bore 8 has a free run section 10, which adjoins the piston run
surface 9 and is situated in the second end area 8b of the piston
bore 8 facing toward the crankshaft 5, and whose clear opening
width or whose diameter 10' is greater than the diameter 9' of the
piston run surface 9.
[0064] The diameter 8' of the piston bore 8 or the diameter 9' of
the piston run surface 9 is thus expanded in the second end area 8b
by a free run section 10, in which the cylinder housing 3 is not
contacted by the piston 6 during the piston oscillation, which is
executed in its operating state (see FIG. 10 and FIG. 11).
[0065] The free run section 10 according to the invention can be
implemented, for example, as a recess in the cylinder housing 3
which is rotationally symmetric to the cylinder axis 12 (thus
obvious in FIG. 10 or FIG. 11).
[0066] Instead of a concentric configuration of the free run
section 10 to the piston bore 8, any other desired configuration
and geometric design of the free run section 10 can also be
performed. The free run section 10 can also be implemented as a
chamfer on the inner side of the cylinder housing 3 corresponding
to the piston bore 8.
[0067] In any case, the piston bore 8 has an expanded section in
the second end area 8b facing toward the crankshaft 5, whose clear
cross-sectional width 10' is greater than the piston bore diameter
8' in the area of the piston run surface 9 or than the piston run
surface diameter 9'.
[0068] The free run section 10 is preferably situated in the
cylinder housing 3 so that the piston run surface 9 has a minimal
guide length (measured in the direction of the piston oscillation
or parallel to the cylinder axis 12). In case of such a minimal
guide length, the piston 6 is only lowered, in its bottom dead
center position, far enough into the area of the piston bore 8
corresponding to the piston run surface 9 that the piston 6 is
prevented from falling out of the piston bore 8 and a sufficient
sealing action of the piston 6 in relation to the piston run
surface 9 is provided, i.e., a reliable seal of the cylinder
chamber delimited by the front side 6a of the piston 6 and the
valve plate 16 is ensured. The piston 6 is prevented from falling
out of the piston bore 8 as long as at most half of the axial
length of the piston 6, in its bottom dead center position,
protrudes beyond the piston run surface 9.
[0069] Through the provision of the free run section 10 according
to the invention, whose longitudinal extension 10'' measured in the
oscillation direction of the piston 6 or parallel to the piston run
surface 9 is thus selected so that the piston run surface 9 is
reduced to a minimum guide length, the lateral surface of the
piston 6 is in turn partially exposed in its bottom dead center
position. In the case of a piston-cylinder configuration 28
according to FIG. 10, in which the piston 6 is plunged relatively
deep into the piston bore 8 and the piston run surface 9 is
adjacent to the first end area 8a of the piston bore 8 on the
cylinder head side, the same friction advantage results as in the
case of a configuration according to FIG. 8, in which the piston
run surface 9 overlaps the second end area 8b of the piston bore 8
and the piston partially protrudes out of the cylinder housing
3.
[0070] The distance of the beginning of the piston run surface 9,
facing toward the crankshaft 3, to the rotational axis 11 of the
crankshaft is thus no longer constant (as in the prior art), but
rather variable as a function of the positioning of the free run
section 10 according to the invention.
[0071] Is thus possible to provide a cylinder housing 3, which is
oversized with respect to its axial longitudinal extension, or a
standard mounting body 2, having such a cylinder housing 3, for a
plurality of refrigerant compressor models which differ from one
another through a differing working volume of their piston-cylinder
configurations 28. The cylinder housing 3 or mounting body 2 may
further be adapted in each case so that the lateral surface of the
piston 6 is partially exposed in its bottom dead center position
using the free run section or the piston run surface 9 is reduced
to the minimal guide length.
[0072] It is to be noted that the illustration of the cylinder head
15 and the valve plate 16 situated in the first end area 8a of the
piston bore 8 was dispensed with.
[0073] The production of the free run section 10 or the expansion
of the piston bore 8 can be performed by suitable machining methods
such as boring, turning, or milling. The free run section 10 is
preferably produced by simple boring out of the piston bore 8 to an
enlarged diameter.
[0074] The clear cross-sectional width 10' of the free run section
10 is greater in this case by more than 2/100 mm, preferably by
more than 1/10 mm than the piston bore diameter 8'. A simple
installation of the piston 6 in the cylinder housing 3 from the
side of the crankshaft-side second end area 8b of the piston bore 8
is made possible in that the clear cross-sectional with 10' of the
free run section 10 is preferably greater by more than 1 mm than
the piston bore diameter 8'.
[0075] Furthermore, the installation of the piston 6 from the
second piston bore end area 8b in the cylinder housing 3 is
promoted by the design of a corresponding transition between the
free run section 10 and the piston run surface 9 of the cylinder
housing 3. Such a transition is preferably implemented using a
chamfer 38 (shown by dashed lines in a detail view according to
FIG. 11) or a radius 39. The chamfer 38 or the radius 39 preferably
runs concentrically to the cylinder axis 12.
[0076] It is to be noted that the cylinder housing 3 can also be
implemented in multiple parts, to achieve manufacturing economy
advantages. Thus, for example, insert elements provided for
accommodating the piston 6 may be provided, which are inserted into
corresponding recesses (following the cylinder axis 12) in the
cylinder housing 3, preferably pressed in or also fixed by another
type of fastening technology. Such insert elements can be
cylindrical bushes, for example, whose axial length is dimensioned
so that all configurations of the piston-cylinder configuration 28
according to the invention as described above and shown in FIGS.
1-11 may be implemented. Such insert elements have a hole (running
along the cylinder axis 12 in the installed position in the
cylinder housing 3), by which the piston run surface 9 is formed.
The insert element can either form only the piston run surface 9 or
also the free run section 10, i.e., it can have a corresponding
transition or step jump.
[0077] A particularly advantageous installation of the
above-mentioned piston bolt 23, which links the piston 6 on the
connecting rod 7, in a corresponding piston bolt hole 22 of the
piston 6, is achieved in that the piston bolt 23 is inserted into
the piston bolt hole 22 in a position in which the piston 6 was
displaced in the direction of the cylinder head 15 in relation to
its bottom dead center position (see FIG. 1).
[0078] In this case, the cylinder housing 3 has a first
installation opening 24, which runs essentially perpendicularly to
the cylinder axis 12 and is best visible in FIG. 3, the central
axis 25 of this first installation opening 24 being displaced by a
distance amount y (shown in FIG. 1) in the direction of the first
end area 8a of the piston bore 8 to the piston bolt axis 21 of the
piston 6, which is located in its bottom dead center position.
[0079] A counter holding tool (not shown) can be inserted into this
first installation opening 24, this tool penetrating up to a
particular desired depth or end position into the piston bolt hole
22 and offering a stop for the piston bolt 23, which is inserted
from a diametrically opposing side of the cylinder housing 3 into
the piston bolt hole 22 and into the second connecting rod eye 7b
of the connecting rod 7. The connecting rod 7 or its second
connecting rod eye 7b is lowered in this case into a connecting rod
receptacle 36 provided inside the piston 6.
[0080] In that the counter holding tool, which is inserted into the
first installation opening 24 or into the piston bolt hole, fixes
the piston 6 in a position inside the cylinder housing 3, in which
the piston bolt axis 21 is aligned with axis 25 of the first
installation opening 24, the piston bolt 23 can be brought into its
operating position according to FIG. 3 or pressed into the cylinder
housing 3 from the side of a second installation opening 37, which
is diametrically opposite to the first installation opening 24. The
stop formed by the counter holding tool is further required for the
purpose of fixing the piston bolt 23 in its operating position
using a fixing pin (optionally provided, not shown).
[0081] The second installation opening 37 can be a through hole in
the cylinder housing 3 running orthogonally to the cylinder axis 12
or also any other desired opening. It is to be noted that the first
installation opening 24 can also be used for inserting the piston
bolt 23 into the piston bolt hole 22.
[0082] Through an installation according to the invention of the
piston bolt 23 into a piston 6 located above its bottom dead center
position, greater design freedom is made possible for the
constructive design of the piston-cylinder configuration 28 or for
situating the free run section 10 according to the invention and
the piston run surface 9 inside the cylinder housing 3.
LIST OF REFERENCE NUMERALS
[0083] 1 refrigerant compressor [0084] 2 mounting body [0085] 3
cylinder housing [0086] 4 main bearing for crankshaft [0087] 5
crankshaft [0088] 6 piston [0089] 6a front side of the piston
[0090] 6' piston length [0091] 7 connecting rod [0092] 7a first
connecting rod eye [0093] 7b second connecting rod eye [0094] 7c
shaft section of the connecting rod [0095] 8 piston bore [0096] 8a
first end area of the piston bore [0097] 8b second end area of the
piston bore [0098] 8' diameter of the piston bore [0099] 9 piston
run surface [0100] 9' diameter of the piston run surface [0101] 10
free run section [0102] 10' clear opening width of the free run
section [0103] 10'' longitudinal extension of the free run section
[0104] 11 crankshaft axis [0105] 12 cylinder axis [0106] 13
electric motor [0107] 13a stator [0108] 13b rotor [0109] 14
compressor housing [0110] 15 cylinder head [0111] 16 valve plate
[0112] 17 fixing elements for cylinder head [0113] 18 eccentric
disc [0114] 19 crank pin [0115] 20 axis of the crank pin [0116] 21
piston bolt axis [0117] 22 piston bolt hole [0118] 23 piston bolt
[0119] 24 first installation opening [0120] 25 axis of the
installation opening [0121] 26 holding element [0122] 27 mounting
unit for electric motor [0123] 28 piston-cylinder configuration
[0124] 29 screw elements [0125] 30 through hole [0126] 31 first
support base element [0127] 31a first bearing pedestal of the first
support base element [0128] 31b second bearing pedestal of the
first support base element [0129] 32 second support base element
[0130] 32a first bearing pedestal of the second support base
element [0131] 32b second bearing pedestal of the second support
base element [0132] 33 threaded holes [0133] 34 upper winding head
of the motor winding [0134] 35 supply and drain lines [0135] 36
connecting rod receptacle [0136] 37 second installation opening
[0137] 38 chamfer [0138] 39 radius [0139] x piston stroke [0140] y
distance amount between the central axis 25 of the installation
opening 24 and the piston bolt axis 21 [0141] z longitudinal axis
of the working chamber
* * * * *