U.S. patent application number 16/333574 was filed with the patent office on 2019-10-10 for screw compressor for a utility vehicle.
This patent application is currently assigned to KNORR-BREMSE Systeme fuer Nutzfahrzeuge GmbH. The applicant listed for this patent is KNORR-BREMSE Systeme fuer Nutzfahrzeuge GmbH. Invention is credited to Gilles HEBRARD, Jean-Baptiste MARESCOT, Joerg MELLAR, Thomas WEINHOLD.
Application Number | 20190309747 16/333574 |
Document ID | / |
Family ID | 59969134 |
Filed Date | 2019-10-10 |
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United States Patent
Application |
20190309747 |
Kind Code |
A1 |
HEBRARD; Gilles ; et
al. |
October 10, 2019 |
Screw Compressor for a Utility Vehicle
Abstract
A screw compressor for a utility vehicle has a rotor housing, in
which screw rotors of the screw compressor are arranged, a housing
cover, and an air outlet pipe arranged on an output side of the
housing cover and having a riser. The air outlet pipe has at least
one oil separator.
Inventors: |
HEBRARD; Gilles; (Muenchen,
DE) ; MARESCOT; Jean-Baptiste; (Muenchen, DE)
; MELLAR; Joerg; (Muenchen, DE) ; WEINHOLD;
Thomas; (Muenchen, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KNORR-BREMSE Systeme fuer Nutzfahrzeuge GmbH |
Muenchen |
|
DE |
|
|
Assignee: |
KNORR-BREMSE Systeme fuer
Nutzfahrzeuge GmbH
Muenchen
DE
|
Family ID: |
59969134 |
Appl. No.: |
16/333574 |
Filed: |
September 19, 2017 |
PCT Filed: |
September 19, 2017 |
PCT NO: |
PCT/EP2017/073573 |
371 Date: |
May 23, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F04C 29/02 20130101;
F04C 2/04 20130101; F04C 2/22 20130101; F04C 18/16 20130101; F04C
29/12 20130101; F04C 29/0092 20130101; F04C 29/026 20130101 |
International
Class: |
F04C 2/22 20060101
F04C002/22; F04C 2/04 20060101 F04C002/04; F04C 29/00 20060101
F04C029/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 21, 2016 |
DE |
10 2016 011 506.8 |
Claims
1-7. (canceled)
8. A screw compressor for a utility vehicle, comprising: a housing
cover in which screws of the screw compressor are arranged; and an
air outlet pipe which is arranged at an outlet side of the housing
cover and includes a riser line, wherein the air outlet pipe has at
least one oil separator.
9. The screw compressor as claimed in claim 8, wherein the oil
separator comprises an oil return opening.
10. The screw compressor as claimed in claim 9, wherein the oil
return opening connects an interior of the air outlet pipe to the
oil sump.
11. The screw compressor as claimed in claim 10, wherein the air
outlet pipe has an attachment piece by which the air outlet pipe is
connected to the housing cover, and the oil return opening is
arranged in a region of the attachment piece or adjacent to the
attachment piece.
12. The screw compressor as claimed in claim 9, wherein the oil
return opening is a bore.
13. The screw compressor as claimed in claim 10, wherein the air
outlet pipe is at least partially of conical form.
14. The screw compressor as claimed in claim 13, wherein the riser
line is of conical form at an end side.
Description
BACKGROUND AND SUMMARY OF THE INVENTION
[0001] The present invention relates to a screw compressor for a
utility vehicle.
[0002] Screw compressors for utility vehicles are already known
from the prior art. Such screw compressors are used to provide the
compressed air required for the brake system of the utility
vehicle, for example.
[0003] In this context, in particular oil-filled compressors, in
particular also screw compressors, are known, in the case of which
it is necessary to regulate the oil temperature. This is generally
realized by virtue of an external oil cooler being provided which
is connected to the oil-filled compressor and to the oil circuit
via a thermostat valve. Here, the oil cooler is a heat exchanger
which has two mutually separate circuits, wherein the first circuit
is provided for the hot liquid, that is to say the compressor oil,
and the second circuit is provided for the cooling liquid. As
cooling liquid, use may for example be made of air, water mixtures
with an antifreeze, or another oil.
[0004] This oil cooler must then be connected to the compressor oil
circuit by means of pipes or hoses, and the oil circuit must be
safeguarded against leakage.
[0005] This external volume must furthermore be filled with oil,
such that the total quantity of oil is also increased. The system
inertia is thus increased. Furthermore, the oil cooler must be
mechanically accommodated and fastened, either by means of brackets
situated in the surroundings or by means of a separate bracket,
which necessitates additional fastening means and also structural
space.
[0006] U.S. Pat. No. 4,780,061 has already disclosed a screw
compressor with an integrated oil cooling arrangement.
[0007] Furthermore, DE 37 17 493 A1 discloses a screw compressor
installation which is arranged in a compact housing and which has
an oil cooler on the electric motor of the screw compressor.
[0008] A generic screw compressor is already known for example from
DE 10 2004 060 417 B4.
[0009] It is therefore the object of the present invention to
advantageously further develop a screw compressor for a utility
vehicle of the type mentioned in the introduction, in particular
such that an initial oil separation can take place already before
the fluid, in particular air, compressed by the screw compressor
reaches the oil separator.
[0010] This object is achieved according to the invention by a
screw compressor for a utility vehicle equipped with a rotor
housing in which the screws of the screw compressor are arranged.
An air outlet pipe is arranged at the outlet side of the housing
cover and has a riser line, wherein the air outlet pipe has at
least one oil separator.
[0011] The invention is based on the underlying concept, in the
case of a screw compressor, of performing an initial oil separation
already at the outlet side of the housing cover and of the screws
which serve for the compression for example of the air or of some
other fluid. This initial oil separation is realized not by way of
a conventional oil separator but rather already by way of the air
outlet pipe through which the compressed fluid, in particular the
compressed air, is discharged out of the rotor housing or, after
the compression by the screws, onward in the screw compressor.
[0012] By means of this oil separation that takes place already in
the air outlet pipe, it is made possible for the efficiency of the
oil separation to be considerably improved. In this way, it is also
achieved that the oil separator may possibly be dimensioned and
configured differently, because an initial oil separation takes
place already upstream thereof.
[0013] Provision may furthermore be made for the oil separator
means to have an oil return opening. Such an oil return opening may
for example be an opening in a wall of the air outlet pipe, through
which opening the oil that precipitates on the walls of the air
outlet pipe can run out.
[0014] In particular, provision may be made for the oil return
opening to connect the interior of the air outlet pipe to the oil
sump. By means of this alone, a simple return of oil is
achieved.
[0015] Provision may furthermore be made for the air outlet pipe to
have an attachment piece by means of which the air outlet pipe is
connected to the housing cover, wherein the oil return opening is
arranged in the region of the attachment piece or adjacent to the
attachment piece. It is thus made possible for the oil return
opening to be arranged so as to relatively directly follow the
outlet of the housing cover, that is to say at the location
adjoined by the air outlet pipe. Any oil that has already
precipitated there can thus be directly discharged out of the air
outlet pipe.
[0016] The oil return opening may be formed by a simple bore. This
permits simple assembly and at the same time also simple
positioning of the oil return opening.
[0017] Provision may furthermore be made for the air outlet pipe to
be at least partially of conical form. By means of a conical form
of the air outlet pipe, it is made possible for oil particles to be
separated out of the air, and for these to be prevented from
exiting the air outlet pipe, owing to the action of gravitational
force.
[0018] In particular, provision may be made for the riser line to
be of conical form at an end side. By means of such a conical
widening of the riser line, it is made possible for the effect of
separating oil particles and droplets out of the air under the
action of gravitational force to be improved. The oil particles
separated out in this way fall back into the air outlet pipe and
collect in the region adjacent to the attachment piece of the air
outlet pipe, and there, can flow via the oil return opening back
into the oil sump.
[0019] Further details and advantages of the invention will now be
discussed in more detail on the basis of an exemplary embodiment
illustrated in the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 shows a schematic sectional drawing through a screw
compressor according to the invention;
[0021] FIG. 2 shows a perspective detail view of the rotor housing
of the screw compressor, with air outlet pipe of the screw
compressor, as per FIG. 1, and
[0022] FIG. 3 shows a perspective sectional drawing through the air
outlet pipe as per FIG. 2.
DETAILED DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1 shows, in a schematic sectional illustration, a screw
compressor 10 in the context of an exemplary embodiment of the
present invention.
[0024] The screw compressor 10 has a fastening flange 12 for the
mechanical fastening of the screw compressor 10 to an electric
motor (not shown in any more detail here).
[0025] What is shown, however, is the input shaft 14, by which the
torque from the electric motor is transmitted to one of the two
screws 16 and 18, specifically the screw 16.
[0026] The screw 18 meshes with the screw 16 and is driven by means
of the latter.
[0027] The screw compressor 10 has a housing 20 in which the main
components of the screw compressor 10 are accommodated.
[0028] The housing 20 is filled with oil 22.
[0029] At the air inlet side, an inlet connector 24 is provided on
the housing 20 of the screw compressor 10. The inlet connector 24
is in this case designed such that an air filter 26 is arranged at
said inlet connector. Furthermore, an air inlet 28 is provided
radially on the air inlet connector 24.
[0030] In the region between the inlet connector 24 and the point
at which the inlet connector 24 joins to the housing 20, there is
provided a spring-loaded valve insert 30, which is designed here as
an axial seal.
[0031] This valve insert 30 serves as a check valve.
[0032] Downstream of the valve insert 30, there is provided an air
feed channel 32 which feeds the air to the two screws 16, 18.
[0033] At the outlet side of the two screws 16, 18, there is
provided an air outlet pipe 34 with a riser line 36.
[0034] In the region of the end of the riser line 36, there is
provided a temperature sensor 38 by means of which the oil
temperature can be monitored.
[0035] Also provided in the air outlet region is a holder 40 for an
air deoiling element 42.
[0036] In the assembled state, the holder 40 for the air deoiling
element has the air deoiling element 42 in the region facing toward
the base (as also shown in FIG. 1).
[0037] Also provided, in the interior of the air deoiling element
42, is a corresponding filter screen or known filter and oil
separation devices 44, which will not be specified in any more
detail.
[0038] In the central upper region in relation to the assembled and
operationally ready state (that is to say as shown in FIG. 1), the
holder for the air deoiling element 42 has an air outlet opening 46
which leads to a check valve 48 and a minimum pressure valve 50.
The check valve 48 and the minimum pressure valve 50 may also be
formed in one common combined valve.
[0039] The air outlet 51 is provided downstream of the check valve
48.
[0040] The air outlet 51 is generally connected to correspondingly
known compressed-air consumers.
[0041] In order for the oil 22 that is situated and separated off
in the air deoiling element 42 to be returned again into the
housing 20, a riser line 52 is provided which has a filter and
check valve 54 at the outlet of the holder 40 for the air deoiling
element 42 at the transition into the housing 20.
[0042] A nozzle 56 is provided, downstream of the filter and check
valve 54, in a housing bore. The oil return line 58 leads back into
approximately the central region of the screw 16 or of the screw 18
in order to feed oil 22 thereto again.
[0043] An oil drain screw 59 is provided in the base region, in the
assembled state, of the housing 20. By means of the oil drain screw
59, a corresponding oil outflow opening can be opened, via which
the oil 22 can be drained.
[0044] Also provided in the lower region of the housing 20 is the
attachment piece 60 to which the oil filter 62 is fastened. Via an
oil filter inlet channel 64, which is arranged in the housing 20,
the oil 22 is conducted firstly to a thermostat valve 66.
[0045] Instead of the thermostat valve 66, it is possible for an
open-loop and/or closed-loop control device to be provided by means
of which the oil temperature of the oil 22 situated in the housing
20 can be monitored and set to a setpoint value.
[0046] Downstream of the thermostat valve 66, there is then the oil
inlet of the oil filter 62, which, via a central return line 68,
conducts the oil 22 back to the screw 18 or to the screw 16 again,
and also to the oil-lubricated bearing 70 of the shaft 14. Also
provided in the region of the bearing 70 is a nozzle 72, which is
provided in the housing 20 in conjunction with the return line
68.
[0047] The cooler 74 is connected to the attachment piece 60, as
will be discussed in more detail below in FIGS. 2 to 4.
[0048] In the upper region of the housing 20 (in relation to the
assembled state), there is situated a safety valve 76, by means of
which an excessively high pressure in the housing 20 can be
dissipated.
[0049] Upstream of the minimum pressure valve 50, there is situated
a bypass line 78, which leads to a relief valve 80. Via said relief
valve 80, which is activated by means of a connection to the air
feed 32, air can be returned into the region of the air inlet 28.
In this region, there may be provided a ventilation valve (not
shown in any more detail) and also a nozzle (diameter constriction
of the feeding line).
[0050] Furthermore, approximately at the level of the line 34, an
oil level sensor 82 may be provided in the outer wall of the
housing 20. Said oil level sensor 82 may for example be an optical
sensor, and may be designed and configured such that, on the basis
of the sensor signal, it can be identified whether the oil level
during operation is above the oil level sensor 82 or whether the
oil level sensor 82 is exposed, and thus the oil level has
correspondingly fallen.
[0051] In conjunction with this monitoring, it is also possible for
an alarm unit to be provided which outputs or transmits a
corresponding error message or warning message to the user of the
system.
[0052] The function of the screw compressor 10 shown in FIG. 1 is
as follows.
[0053] Air is fed via the air inlet 28 and passes via the check
valve 30 to the screws 16, 18, where the air is compressed. The
compressed air-oil mixture, which, having been compressed by a
factor of between 5 and 16 downstream of the screws 16 and 18,
rises through the outlet line 34 via the riser pipe 36, is blown
directly onto the temperature sensor 38.
[0054] The air, which still partially carries oil particles, is
then conducted via the holder 40 into the air deoiling element 42
and, if the corresponding minimum pressure is attained, passes into
the air outlet line 51.
[0055] The oil 22 situated in the housing 20 is kept at operating
temperature via the oil filter 62 and possibly via the heat
exchanger 74.
[0056] If no cooling is necessary, the heat exchanger 74 is not
used and is also not activated.
[0057] The corresponding activation is performed by means of the
thermostat valve 66. After purification in the oil filter 62, oil
is fed via the line 68 to the screw 18 or to the screw 16, and also
to the bearing 70. The screw 16 or the screw 18 is supplied with
oil 22 via the return line 52, 58, and the purification of the oil
22 takes place here in the air deoiling element 42.
[0058] By means of the electric motor (not shown in any more
detail), which transmits its torque via the shaft 14 to the screw
16, which in turn meshes with the screw 18, the screws 16 and 18 of
the screw compressor 10 are driven.
[0059] By means of the relief valve 80 (not shown in any more
detail), it is ensured that the high pressure that prevails for
example at the outlet side of the screws 16, 18 in the operational
state cannot be enclosed in the region of the feed line 32, and
that, instead, in particular during the start-up of the compressor,
there is always a low inlet pressure, in particular atmospheric
pressure, prevailing in the region of the feed line 32. Otherwise,
upon a start-up of the compressor, a very high pressure would
initially be generated at the outlet side of the screws 16 and 18,
which would overload the drive motor.
[0060] FIG. 2 shows, in a perspective view, the housing cover 20a
of the screw compressor 10 as shown in FIG. 1.
[0061] The housing cover 20a has an outlet which is adjoined by the
air outlet pipe 34.
[0062] Here, the air outlet pipe 34 has an attachment piece 34a, by
means of which the air outlet pipe 34 is connected to the housing
cover 20a.
[0063] The air outlet pipe 34 furthermore has a riser line 36.
[0064] Here, the riser line 36 is of conically widened form,
specifically in the end-side region 36a.
[0065] The air outlet pipe 34 furthermore has an oil return opening
100 in the region of its attachment piece 34a.
[0066] Here, the oil return opening 100 is formed as a bore.
[0067] The oil return opening 100 connects the interior of the air
outlet pipe 34 to the oil sump 22a.
[0068] By means of the conical widening and the oil return opening
100, the air outlet pipe 34 has, altogether, an oil separator which
serves for the initial oil separation even before the air
compressed by the screw compressor 10 is conducted through the oil
separator.
[0069] Here, the oil separation occurs in that, owing to the
conical widening and the reduction of the flow speed that is also
achieved as a result in this region, oil particles situated in the
air stream can fall back again owing to the action of gravitational
force, can precipitate on the walls in the interior of the air
outlet pipe 34, and can then flow back through the oil return
opening 100 into the oil sump 22a.
[0070] FIG. 3 shows a perspective sectional drawing through the air
outlet pipe as per FIG. 2.
LIST OF REFERENCE DESIGNATIONS
[0071] 10 Screw compressor [0072] 12 Fastening flange [0073] 14
Input shaft [0074] 16 Screws [0075] 18 Screws [0076] 20 Housing
[0077] 20a Housing cover [0078] 22a Oil sump [0079] 22 Oil [0080]
24 Inlet connector [0081] 26 Air filter [0082] 28 Air inlet [0083]
30 Valve insert [0084] 32 Air feed channel [0085] 34 Air outlet
pipe [0086] 34a Attachment piece [0087] 36 Riser line [0088] 36a
End-side region [0089] 38 Temperature sensor [0090] 40 Holder for
an air deoiling element [0091] 42 Air deoiling element [0092] 44
Filter screen or known filter or oil separation devices [0093] 46
Air outlet opening [0094] 48 Check valve [0095] 50 Minimum pressure
valve [0096] 51 Air outlet [0097] 52 Riser line [0098] 54 Filter
and check valve [0099] 56 Nozzle [0100] 58 Oil return line [0101]
59 Oil drain screw [0102] 60 Attachment piece [0103] 60a Outer ring
[0104] 60b Inner ring [0105] 62 Oil filter [0106] 64 Oil filter
inlet channel [0107] 66 Thermostat valve [0108] 68 Return line
[0109] 70 Bearing [0110] 72 Nozzle [0111] 76 Safety valve [0112] 78
Bypass line [0113] 80 Relief valve [0114] 82 Oil level sensor
[0115] 100 Oil return opening
* * * * *