EP3516232A1

EP3516232A1 - Screw compressor system for a utility vehicle

Info

Publication number: EP3516232A1
Application number: EP17769062.5A
Authority: EP
Inventors: Gilles Hebrard; Jean-Baptiste Marescot; Jörg MELLAR; Thomas Weinhold; Engelbert KÖCK
Original assignee: Knorr Bremse Systeme fuer Nutzfahrzeuge GmbH
Current assignee: Knorr Bremse Systeme fuer Nutzfahrzeuge GmbH
Priority date: 2016-09-21
Filing date: 2017-09-19
Publication date: 2019-07-31
Also published as: WO2018054856A1; DE102016011439A1; CN109790840A; KR20190044682A; JP2019529794A; BR112019005063A2

Abstract

The present application relates to a screw compressor system (100) for a utility vehicle having at least one screw compressor (10) and at least one open-loop and/or closed-loop control unit (130) for open-loop and/or closed-loop drive control of the screw compressor (10), wherein the screw compressor (10) comprises at least one air outlet (51) having at least one minimum pressure valve (50) for controlling the operating pressure at the air outlet (51) and at least one relief valve (80), wherein the screw compressor (10) can be switched off by means of the open-loop and/or closed-loop control unit (130) such that, by opening the relief valve (80), the operating pressure within the screw compressor (10) is reduced for a predetermined period of time, in order to make it possible to close the minimum pressure valve (50).

Description

DESCRIPTION

The present invention relates to a screw compressor system for a commercial vehicle having at least one screw compressor with at least one control and / or regulating unit for drive control and / or regulation of the vehicle

Screw compressor. Screw compressors for commercial vehicles are already known from the prior art. Such screw compressors are used to provide the necessary compressed air for, for example, the braking system of the commercial vehicle.

In this context, in particular oil-filled compressors, especially screw compressors are known. The lubrication concept of such

Screw compressors provides that for lubrication of the screws

necessary oil is first transported with the compressed compressed air. Before the compressed air can be supplied to the air treatment device, the oil is separated from the compressed air in an oil separation device and from there e.g. returned to the integrated oil reservoir or screws of the screw compressor.

Since the air treatment device must be regenerated at regular intervals by venting, for this purpose, the operation of the

Screw compressor stopped (above a certain cut-off pressure). to

Securing the pressure in the screw compressor against the

Air treatment device has this a minimum pressure valve. During regeneration, there is usually a rapid pressure drop in the

Air treatment device until the closing pressure of the minimum pressure valve is reached. The pressure differential between the screw compressor and the air treatment unit temporarily causes oil from the oil separator to accidentally enter the oil separator

Air treatment device passes. Another unwanted effect of the rapid pressure reduction is a foaming of the oil contained in the screw compressor, whereby damage can be caused in particular by lack of lubrication on exposed components of the screw compressor such as bearings or screws.

To avoid the unwanted oil transfer usually additional pressure holding valves between screw compressor and air treatment device are provided, however, u.a. additional manufacturing, assembly and

Cause development costs.

A generic screw compressor is already known, for example, from DE 10 2004 060417 [34.

It is the object of the present invention to further develop a screw compressor system of the type mentioned in an advantageous manner, in particular

in that the drive control and / or regulation of the

Screw compressor simplified and can be configured reliably.

This object is achieved by a screw compressor system with the features of claim 1. Thereafter, it is provided that a

Screw compressor system for a commercial vehicle with at least one

Screw compressor and with at least one control and / or

Control unit for drive control and / or regulation of the

Screw compressor is provided, wherein the screw compressor at least one air outlet with at least one minimum pressure valve for controlling the

Operating pressure at the air outlet and at least one relief valve, wherein the screw compressor can be switched off by means of the control and / or regulating unit, so that by opening the relief valve, the working pressure within the

Screw compressor for a predetermined period of time is lowered, so that a closing of the minimum pressure valve is made possible.

The invention is based on the basic idea, the regeneration of downstream pneumatic elements (eg the air treatment device) only after a after a stop of the drive of the screw compressor, so that the pressure in the screw compressor slowly over the

Relief valve has dropped such that foaming of the oil or leakage of oil through the air outlet is reliably prevented. This is achieved by leaving the relief valve open until the pressure in the

Screw compressor has dropped so much that the minimum pressure valve due

Below the minimum pressure for opening or closing the

Minimum pressure valve closes. Due to the fact that in certain

Operating situations, the line connected to the air outlet, for example, for the regeneration of downstream elements and pneumatic systems of the

Commercial vehicle must be vented, it is important to ensure that in such a condition is not due to excessive prevailing working pressure in the

Screw compressor oil is introduced from the screw compressor into the air outlet inside and thus leads to contamination of downstream or connected to the screw compressor elements. In addition, it may also come to such an exit to an oil leakage from the commercial vehicle systems in the area, which should be avoided. By opening the

Relief valve is achieved that in any case the pressure in

Screw compressor may drop below the minimum pressure at which the

Minimum pressure valve closes. This reliably prevents the escape of oil into the air outlet.

For example, it can be provided that the control and / or regulating unit is part of the screw compressor. As a result, a compact structure is formed and it is not necessary to have access to external components.

In principle, however, it is also conceivable that the control and / or regulating unit is part of an air treatment device of the commercial vehicle. Here is already a corresponding control available, which can be easily shared.

It is also conceivable that the control and / or regulating unit is part of an engine or vehicle control of the commercial vehicle. Again, it would be possible to access an already existing component of the commercial vehicle. In principle, however, it is also conceivable that the control and / or regulating unit is designed as a separate control and / or regulating unit. This allows, for example, a simple installation and also a simple exchange or

simple upgrades.

It is also conceivable that the control and / or regulating unit is part of a drive of the screw compressor. In this case, it would also be possible to rely on the already provided by the drive control and / or

Control infrastructure.

It is conceivable that the predetermined period of time is at least about 10 seconds, in particular at least about 15 seconds. Such a period is sufficient in the conventional vent valves to ensure a safe drop in the

Operating pressure or prevailing pressure in the screw compressor to a pressure level to reach, which is below the pressure level at which the

Minimum pressure valve would open or a pressure level at which the minimum pressure valve transferred from the open position to a closed position.

Furthermore, it is conceivable that the screw compressor system at least one

Has air outlet closure valve. This valve increases the reliability of the screw compressor system by preventing air from flowing back through the air outlet of the screw compressor.

Incidentally, it may be provided that the Luftauslassverschlussventil is part of the screw compressor. Due to the integrated arrangement of the

Air outlet shut-off valve e.g. In the housing of the screw compressor, a particularly compact design can be realized.

Furthermore, it is also conceivable that the Luftauslassverschlussventil is part of the air treatment device. Depending on the application, the air outlet valve in the air conditioning device be integrated, which also leads to a particularly compact design and functional integration.

Furthermore, it can be provided that the minimum pressure valve and the

Air outlet valve as a combined Mindestdruckventil- and / or

Air outlet valve unit are formed. This achieves a compact design. Overall, space can thus be saved, whereby the screw compressor system can be designed to be smaller overall construction. In addition, it can be provided that the minimum pressure valve below a voltage applied to the minimum pressure valve of about half to three quarters of

Working pressure of the screw compressor closes. Due to the opening of the minimum pressure valve at half to three quarters of the working pressure, in particular during the initial pressure build-up, the oil can first be pressurized. As a result, first of all, reliable lubrication can take place during the start-up phase of the screw compressor until the minimum pressure valve is opened independently of the pressure of downstream pneumatic elements.

Further details and advantages of the invention will now be explained in more detail with reference to an embodiment shown in the drawings.

Show it:

Fig. 1 is a schematic sectional view through an inventive

Screw compressor; and

Fig. 2 is a schematic drawing of the screw compressor system according to the present invention. Fig. 1 shows a schematic sectional view of a screw compressor 10 in the sense of an embodiment of the present invention. The screw compressor 10 has a mounting flange 12 for mechanical attachment of the screw compressor 10 to a drive not shown here in detail in the form of an electric motor. Shown, however, is the input shaft 14, via which the torque from the electric motor to one of the two screws 16 and 18, namely the screw 16 is transmitted.

The screw 18 meshes with the screw 16 and is driven by this. The screw compressor 10 has a housing 20 in which the essential components of the screw compressor 10 are housed.

The housing 20 is filled with oil 22. Air inlet side is on the housing 20 of the screw compressor 10 a

Inlet port 24 is provided. The inlet nozzle 24 is designed such that an air filter 26 is arranged on it. In addition, an air inlet 28 is provided radially on the air inlet pipe 24. In the area between inlet port 24 and the point at which the inlet port 24 attaches to the housing 20, a spring-loaded valve core 30 is provided, designed here as an axial seal.

This valve insert 30 serves as a check valve.

Downstream of the valve core 30, an air supply channel 32 is provided, which supplies the air to the two screws 16, 18.

On the output side of the two screws 16, 18, an air outlet pipe 34 is provided with a riser 36.

In the region of the end of the riser 36, a temperature sensor 38 is provided, by means of which the oil temperature can be monitored. Furthermore, a holder 40 for an air de-oiling element 42 is provided in the air outlet area.

The holder 40 for the air de-oiling element has in the assembled state in the area facing the bottom (as shown in Fig. 1), the air de-oiling element 42.

It is further provided in the interior of the Luftentölelements 42 a corresponding

Filter screen or known filter and Ölabscheidevorrichtungen 44, which are not specified in detail.

In the central upper area, relative to the assembled and ready-to-use state (ie as shown in FIG. 1), the holder for the air de-oiling element 40 has a

Air outlet opening 46, which lead to a Luftauslassverschlussventil 48 and a minimum pressure valve 50. According to this embodiment is thus the

Air outlet valve 48 Part of the screw compressor 10.

However, the Luftauslassverschlussventil 48 also part of the

Air treatment device 120 be. However, the air outlet closure valve 48 need not necessarily be part of the screw compressor 10 or the air conditioning device 120. Rather, it is generally conceivable that the screw compressor system 100 is the

Air outlet closure valve 48 has. Thus, it can be decided depending on the application, where the Luftauslassverschlussventil 48 within the

Screw compressor system 100 is to be arranged.

The Luftauslassverschlussventil 48 and the minimum pressure valve 50 may also be formed in a common, combined valve. Following the Luftauslassverschlussventils 48 of the air outlet 51 is provided.

The air outlet 51 is connected to correspondingly known compressed air consumers in the rule. In order to return the oil 22 located and separated in the air de-oiling element 42 back into the housing 20, a riser 52 is provided which has the outlet of the holder 40 for the air de-oiling element 42 when passing into the housing 20 a filter and check valve 54.

Downstream of the filter and check valve 54, a nozzle 56 is provided in a housing bore. The oil return line 58 leads back approximately in the middle region of the screw 16 or the screw 18 to supply oil 22 again.

Within the assembled state of the bottom portion of the housing 20, an oil drain plug 59 is provided. About the oil drain plug 59, a corresponding oil drain opening can be opened, via which the oil 22 can be drained.

In the lower region of the housing 20 and the projection 60 is present, to which the oil filter 62 is attached. Via an oil filter inlet channel 64, which is arranged in the housing 20, the oil 22 is first passed to a thermostatic valve 66. Instead of the thermostatic valve 66, a control and / or

Regulation means may be provided by means of which the Öttemperatur of the oil 22 located in the housing 22 can be monitored and adjusted to a desired value.

Downstream of the thermostatic valve 66 is then the oil inlet of the Ötfilters 62, which leads via a central return line 68, the oil 22 back to the screw 18 or the screw 16, but also to the oil-lubricated bearing 70 of the shaft 14. In the region of the bearing 70, a nozzle 72 is provided, which is provided in the housing 20 in connection with the return line 68. The cooler 74 is connected to the projection 60. In the upper region of the housing 20 (relative to the mounted state) there is a safety valve 76, via which an excessive pressure in the housing 20 can be reduced. In addition, the housing in the upper area (relative to the mounted

State) on a relief valve (80). Before the minimum pressure valve 50 is a bypass line 78, which leads to the relief valve 80. About this

Relief valve 80, which is controlled by means of a connection to the air supply 32, air can be returned to the region of the air inlet 28. In this area, a vent valve not shown in detail and also a nozzle

(Reduction in diameter of the feeding line) may be provided.

In addition, approximately at the level of the conduit 34 in the outer wall of the

Housing 20 an oil level sensor 82 may be provided. This oil level sensor 82 may, for example, be an optical sensor and designed and set up so that it can be determined from the sensor signal whether the oil level is above the oil level sensor 82 during operation or if the oil level sensor 82 is free and the oil level has dropped accordingly. In connection with this monitoring, an alarm unit can also be provided which outputs or forwards an appropriate error message or warning message to the user of the system.

The function of the screw compressor 10 shown in FIG. 1 is as follows:

Air is supplied via the air inlet 28 and passes through the check valve 30 to the screws 16, 18, where the air is compressed. The compressed air-oil mixture, which rises by a factor of between 5 and 16 times compression after the screws 16 and 18 through the outlet conduit 34 via the riser 36, is blown directly onto the temperature sensor 38. The air, which still partially carries oil particles, is then guided via the holder 40 into the air de-oiling element 42 and, provided the corresponding minimum pressure is reached, enters the air outlet line 51. The oil 22 in the housing 20 is conveyed via the oil filter 62 and possibly kept at operating temperature via the heat exchanger 74.

If no cooling is necessary, the heat exchanger 74 is not used and is not switched on.

The corresponding connection is made via the thermostatic valve 68. After the purification in the oil filter 64, oil is supplied via the line 68 to the screw 18 or the screw 16, but also to the bearing 72. The screw 16 or the screw 18 is supplied via the return line 52, 58 with oil 22, here is the purification of the oil 22 in the air de-oiling 42nd

About the electric motor not shown in 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.

About the relief valve 80 is not shown in detail ensures that in the [region of the supply line 32 is not the high pressure prevailing in the operating state, for example, the output side of the screws 16, 18, can be locked, but that in particular at the start of the compressor in the supply line 32nd always a low inlet pressure, in particular atmospheric pressure exists. Otherwise, with a start-up of the compressor, a very high pressure would initially arise on the output side of the screws 16 and 18, which would overload the drive motor.

Incidentally, during the temporary stop of the screw compressor 10, the relief valve 80 has the task of lowering the pressure exerted on the output side with respect to the screws 16, 18 via the bypass line 78 until the minimum pressure valve 50 (at approximately one half to three quarters of the working pressure ) for sure closes. The least! jerk valve (50) serves to control the working pressure at the air outlet (51).

Only after the closing of the minimum pressure valve 50 can the regeneration of, for example, the air treatment device 120 (cf., Fig. 2) be started without the risk that oil from the screw compressor 10 in the

Air treatment device 120 could arrive.

Fig. 2 shows a schematic representation of an inventive

Screw compressor system 100 with the screw compressor 10 shown in FIG. 1, the air outlet 51, a compressed air line 110 connected to the air outlet 51 and an air conditioning device (EAC) 120.

In addition, a control and regulation unit 130 is provided.

The control and regulation unit 130 is here as part of the

Screw compressor 10 is formed.

Basically, however, it can be provided that the control and

Control unit 130 part of the drive of the screw compressor 10, part of the air conditioning device 120, part of the engine control of the commercial vehicle, part of the vehicle control of the commercial vehicle or as a separate control and regulation unit 130 is formed

The screw compressor 10 is turned off by means of the control unit 130 so that opening the relief valve 80 lowers the working pressure within the screw compressor 10 for a predetermined period of time to allow closure of the minimum pressure valve (50). This time span is about 15 seconds in the example shown. But it can for example be in a range between 10 and 15 seconds or even more. In principle, it can be provided that the minimum pressure valve 50 and the Luftauslassverschlussventil 48 as a combined Mindestdruckventil- and

Air outlet valve unit are formed.

Basically, it is provided, as shown in the embodiment as shown in Fig. 1 and Fig. 2, that the minimum pressure valve 50 below an am

Minimum pressure valve 50 applied pressure of about half to three quarters of the working pressure of the screw compressor 10 closes.

LIST OF REFERENCE NUMBERS

10 screw compressor

12 mounting flange

14 input shaft

16 screws

18 screws

20 housing

22 oil

24 inlet ports

26 air filters

28 air intake

30 valve insert

32 air supply duct

34 air outlet pipe

36 riser

38 temperature sensor

40 holder for an air de-oiling element

42 air deoiling element

44 filter screen or known filter or Ölabscheidevorrichtungen

46 air outlet opening

48 Air outlet valve

50 least! jerk valve

51 air outlet

52 riser

54 Filter and check valve

56 nozzle

58 oil return line

59 Oil drain plug

60 approach

62 oil filter

64 oil inlet channel

66 thermostatic valve 68 return line

70 bearings

72 nozzle

74 coolers, heat exchangers

76 safety valve

78 bypass line

80 relief valve

82 oil level sensor

100 screw compressor system

110 compressed air line

120 air treatment device (EAC)

130 control and / or regulating unit

Claims

A screw compressor system (100) for a utility vehicle having at least one screw compressor (10) and at least one control and / or

Control unit (130) for controlling and / or regulating the drive

Screw compressor (10), wherein the screw compressor (10) at least one Luftausiass (51) with at least one minimum pressure valve (50) for controlling the working pressure at Luftausiass (51) and at least one relief valve (80), wherein the screw compressor (10) by means of Control and / or

Control unit (130) is abgeschaitbar, so that by opening the discharge valve (80), the working pressure within the screw compressor (10) is lowered for a predetermined period of time, so that a closing of the minimum pressure valve (50) is made possible.

2. Screw compressor system (100) according to claim 1,

characterized in that

the control and / or regulating unit (130) is part of the

Screw compressor (10) is.

3. screw compressor system (100) according to claim 1,

characterized in that

the control and / or regulating unit (130) is part of a

Air treatment device (120) of the utility vehicle is.

4. screw compressor system (100) according to claim 1,

characterized in that

the control and / or regulating unit (130) is part of an engine or vehicle control of the commercial vehicle.

5. screw compressor system (100) according to claim 1,

characterized in that

the control and / or regulating unit (130) is a separate control and / or regulating unit (130).

6. screw compressor system (100) according to claim 1,

characterized in that

the control and / or regulating unit (130) is part of a drive of the screw compressor (10).

7. screw compressor system (100) according to one of the preceding claims, characterized in that

the predetermined period of time is at least about 10 seconds, in particular at least about 15 seconds.

8. screw compressor system (100) according to one of the preceding claims, characterized in that

the screw compressor system (100) has at least one air outlet closure valve (48).

9. screw compressor system (100) according to claim 8,

characterized in that

the air outlet closing valve (48) is part of the screw compressor (10).

10. screw compressor system (100) according to claim 8,

characterized in that

the air outlet plug valve (48) is part of the air treatment unit (120).

11. Screw compressor system (100) according to one of the preceding claims, characterized in that

the minimum pressure valve (50) and the Luftauslassverschlussventil (48) are designed as a combined minimum pressure valve and Luftauslassverschlussventileinheit.

12. screw compressor system (100) according to one of the preceding claims, characterized in that the minimum pressure valve (50) below a at the minimum pressure valve (50) applied pressure of about half to three quarters of the working pressure of

Screw compressor (10) closes.