DE102016011495A1 - Screw compressor for a commercial vehicle - Google Patents

Abstract

The present invention relates to a screw compressor (10) for a commercial vehicle having at least one housing (20) and a relief valve (80), wherein the relief valve (80) comprises a spring-loaded locking mechanism (100) with at least one spring (102) and at least one closure element (10). 104), the spring (102) having a spring force sized to actuate the closure member (104) when a predefined minimum pressure above atmospheric pressure is reached.

Description

The present invention relates to a screw compressor for a utility vehicle having at least a housing and a relief valve.

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 in which the task is to regulate the oil temperature. This is usually done by having an external oil cooler connected to the oil-filled compressor and the oil circuit via a thermostatic valve. The oil cooler is a heat exchanger which has two separate circuits, wherein the first circuit for the hot liquid, so the compressor oil is provided and the second for the cooling liquid. As a coolant, for example, air, water mixtures can be used with an antifreeze or other oil.

This oil cooler must then be connected to the compressor oil circuit via pipes or hoses and the oil circuit must be secured against leakage.

This external volume must also be filled with oil, so that the total amount of oil is increased. This increases the system inertia. In addition, the oil cooler must be mechanically housed and secured, either by surrounding brackets or by a separate bracket, which requires additional means of improvement, but also space.

From the US 4,780,061 already a screw compressor with integrated oil cooling is known.

Furthermore, the DE 37 17 493 A1 an arranged in a compact housing screw compressor system having an oil cooler on the electric motor of the screw compressor.

A generic screw compressor is for example already out of the DE 10 2004 060 417 B4 known.

It is therefore an object of the present invention to further develop a screw compressor for a commercial vehicle of the type mentioned in an advantageous manner, in particular to the effect that this allows an improved pressure reduction inside the screw compressor.

This object is achieved by a screw compressor for a commercial vehicle with the features of claim 1. Thereafter, it is provided that a screw compressor for a commercial vehicle is provided with at least one housing and a relief valve, wherein the relief valve has a spring-loaded locking mechanism with at least one spring and at least one closure element, wherein the spring has a spring force which is dimensioned such that it actuates the closure element when a predefined minimum pressure above atmospheric pressure is reached.

The invention is based on the idea that the pressure reduction process of the screw compressor is stopped before the internal pressure of the screw compressor has dropped to a pressure equal to or near atmospheric pressure. This makes it possible that there is no blistering or oil foaming inside the housing of the screw compressor or in the oil sump of the screw compressor. By providing a spring-loaded closing mechanism in connection with the relief valve, it becomes possible to find a setting that comparatively easily by means of a spring and at least one closure element, which makes it possible to close the closing mechanism before atmospheric pressure is reached. This can be safely prevented that it comes to foam in the oil inside the housing.

Furthermore, it can be provided that the spring is a helical spring. This allows a simple and inexpensive production. In addition, the handling of such a coil spring is comparatively simple. The design of such a standard component is relatively easy.

The closure element may be a ball. This allows a simple and secure closing of the locking mechanism can be achieved. In addition, balls are comparatively easily available and can also be easily mounted. A spring load by a spring is also easy to implement in a ball. Corresponding surface adjustments need not be made, since the dimensions of the spring and ball can be selected such that they interlock and secure each other.

The spring loaded lock mechanism may be located near the inlet port of the Be arranged screw compressor. Here, a simple integration into the screw compressor, but also at the same time a meaningful ventilation option via the air inlet can be achieved.

In addition, it can be provided that the spring-loaded locking mechanism is arranged in the vent line from the relief valve to the inlet port of the screw compressor. In this area, a simple and safe installation in the example housing of the screw compressor is possible. In addition, safe access to the atmosphere through the air inlet of the screw compressor is ensured.

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:

1 a schematic sectional view through a screw compressor according to the invention; and

2 a schematic sectional view of the spring-loaded locking mechanism of the relief valve for the screw compressor according to 1 ,

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 fastening of the screw compressor 10 on an electric motor not shown here in detail.

Shown, however, is the input shaft 14 , about which the torque from the electric motor on one of the two screws 16 and 18 namely the screw 16 is transmitted.

The screw 18 combs with the screw 16 and is driven by these.

The screw compressor 10 has a housing 20 in which the essential components of the screw compressor 10 are housed.

The housing 20 is with oil 22 filled.

Air inlet side is on the housing 20 of the screw compressor 10 an inlet nozzle 24 intended. The inlet nozzle 24 is designed such that an air filter on it 26 is arranged. There is also a radial air inlet 24 an air intake 28 intended.

In the area between inlet nozzle 24 and the place where the inlet nozzle 24 on the housing 20 attaches, is a spring-loaded valve core 30 provided, designed here as an axial seal.

This valve insert 30 serves as a check valve.

Downstream of the valve core 30 is an air supply duct 32 provided the air the two screws 16 . 18 supplies.

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

In the area of the end of the riser 36 is a temperature sensor 38 provided, by means of which the oil temperature can be monitored.

Further provided in the air outlet area a holder 40 for an air deoiling element 42 ,

The holder 40 for the air de-oiling element has in the mounted state in the area facing the ground (as well as in 1 shown) the Luftentölelement 42 on.

Next is provided inside the Luftentölelement 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 for operation state (ie as in 1 shown), the holder for the Luftentölelement 40 an air outlet opening 46 on that to a check valve 48 and a minimum pressure valve 50 to lead. The check valve 48 and the minimum pressure valve 50 may also be formed in a common, combined valve.

Following the check valve 48 is the air outlet 51 intended.

The air outlet 51 is usually associated with known compressed air consumers.

In the air de-oiling element 42 located and separated oil 22 back in the case 20 due, is a riser 52 provided, the output of the holder 40 for the air deoiling element 42 when crossing into the housing 20 a filter and check valve 54 having.

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

In the assembled state located bottom portion of the housing 20 is an oil drain plug 59 intended. About the oil drain plug 59 a corresponding oil drain opening can be opened, over which the oil 22 can be drained.

In the lower part of the case 20 is also the approach 60 present, at which the oil filter 62 is attached. Via an oil filter inlet channel 64 in the case 20 is arranged, the oil becomes 22 first to a thermostatic valve 66 directed.

Instead of the thermostatic valve 66 a control and / or regulating device may be provided, by means of which the oil temperature of the housing 20 located oil 22 can be monitored and set to a setpoint.

Downstream of the thermostatic valve 66 is then the oil inlet of the oil filter 62 , which has a central return line 68 the oil 22 back to the screw again 18 or to the screw 16 , but also to the oil-lubricated bearing 70 the wave 14 leads. In the area of the warehouse 70 is also a nozzle 72 provided in the housing 20 in connection with the return line 68 is provided.

The cooler 74 is at the beginning 60 connected, as below in the 2 to 4 is explained in more detail.

In the upper part of the case 20 (based on the assembled state) is a safety valve 76 , over which too much pressure in the housing 20 can be reduced.

In front of the minimum pressure valve 50 there is a bypass line 78 leading to a relief valve 80 leads. About this relief valve 80 this by means of a connection to the air supply 32 Air can be controlled in the area of the air intake 28 to be led back. In this area, a vent valve not shown in detail and also a nozzle (diameter reduction of the feeding line) may be provided.

In addition, it can be approximately at the height of the pipe 34 in the outer wall of the housing 20 an oil level sensor 82 be provided. This oil level sensor 82 For example, it can be an optical sensor and can be designed and set up in such a way that it can be detected on the basis of the sensor signal whether the oil level in operation above the oil level sensor 82 or whether the oil level sensor 82 is free and thus the oil level has fallen 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 in 1 shown screw compressor 10 is as follows:
Air gets over the air intake 28 fed and passes through the check valve 30 to the screws 16 . 18 where the air is compressed. The compressed air-oil mixture, with a factor between 5 to 16 times compression after the screws 16 and 18 through the outlet pipe 34 over the riser 36 ascends, is directly on the temperature sensor 38 blown.

The air, which still partially carries oil particles, is then on the holder 40 in the air deoiling element 42 guided and reaches, if the corresponding minimum pressure is reached, in the air outlet pipe 51 ,

That in the case 20 located oil 22 is over the oil filter 62 and optionally via the heat exchanger 74 maintained at operating temperature.

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

The corresponding connection is made via the thermostatic valve 68 , After purification in the oil filter 64 is over the line 68 Oil of the screw 18 or the screw 16 but also the camp 72 fed. The screw 16 or the screw 18 is via the return line 52 . 58 with oil 22 supplied, here is the purification of the oil 22 in the air deoiling element 42 ,

About the electric motor, not shown in detail, the torque on the shaft 14 on the screw 16 transmits, in turn, with the wave 18 combs, the screws are 16 and 18 of the screw compressor 10 driven.

About the relief valve not shown in detail 80 will ensure that in the area of the supply line 32 not the high pressure, in the operating state, for example, on the output side of the screws 16 . 18 prevails, can be locked, but that especially when starting the compressor in the supply line 32 always a low inlet pressure, in particular atmospheric pressure exists. Otherwise, with a start of the compressor would first a very high pressure on the output side of the screws 16 and 18 arise, which would overload the drive motor.

2 shows a schematic sectional view through a spring-loaded locking mechanism 100 for the relief valve of the screw compressor 10 according to 1 ,

The spring-loaded locking mechanism 100 has a spring 102 and a closure element 104 on.

The feather 102 is designed as a helical spring.

The closure element 104 is designed as a sphere.

The spring-loaded locking mechanism 100 is in the area of the air supply of the screw compressor 10 arranged here and in the vent line from the relief valve 80 to the inlet nozzle 24 ,

The feather 102 is here designed such that it has a spring force which is dimensioned such that it the closure element 104 actuated when a predefined minimum pressure above atmospheric pressure is reached.

The function of the spring-loaded locking mechanism 100 can be described as follows:
When stopping the compressor 10 it becomes necessary the inside of the case 20 of the screw compressor 10 to vent and release pressure.

This is done via the relief valve.

In this pressure release but should be stopped before atmospheric pressure is reached. This serves to foam in the oil 22 to prevent.

By means of the spring-loaded locking mechanism 100 it is achieved that the internal pressure remains above the atmospheric pressure.

Here, for example, values between 1.5 to 2.5 bar can be selected. It is conceivable, in particular, to choose a pressure of about 1.5 bar.

The setting of this limit pressure takes place via the setting and selection of the spring 102 and their spring force.

The spring force is dimensioned such that the ball 104 operated the closing mechanism and thus prevents further pressure release when the internal pressure in the housing 20 of the screw compressor 10 no longer sufficient, the closure element 104 against the force of the spring 102 impose.

LIST OF REFERENCE NUMBERS

10

screw compressor

12

mounting flange

14

input shaft

16

screw

18

screw

20

casing

22

oil

24

inlet port

26

air filter

28

air intake

30

valve core

32

air supply duct

34

air discharge

36

riser

38

temperature sensor

40

Holder for an air de-oiling element

42

exhaust filter

44

Filter screen or known filter or Ölabscheidevorrichtungen

46

Air outlet opening

48

check valve

50

Minimum pressure valve

51

air outlet

52

riser

54

Filter and check valve

56

jet

58

Oil return line

59

Oil drain plug

60

approach

62

oil filter

64

Oil filter inlet duct

66

thermostatic valve

68

Return line

70

camp

72

jet

76

safety valve

78

bypass line

80

relief valve

82

Oil Level Sensor

100

spring-loaded locking mechanism

102

feather

104

closure element

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 4780061 [0006]
• DE 3717493 A1 [0007]
• DE 102004060417 B4 [0008]

Claims (5)

Screw compressor ( 10 ) for a commercial vehicle having at least one housing ( 20 ) and a relief valve ( 80 ), the relief valve ( 80 ) a spring-loaded locking mechanism ( 100 ) with at least one spring ( 102 ) and at least one closure element ( 104 ), wherein the spring ( 102 ) has a spring force which is dimensioned such that it the closure element ( 104 ) when a predefined minimum pressure above atmospheric pressure is reached. Screw compressor ( 10 ) according to claim 1, characterized in that the spring ( 102 ) is a coil spring. Screw compressor ( 10 ) according to claim 1 or claim 2, characterized in that the closure element ( 104 ) is a ball. Screw compressor ( 10 ) according to one of the preceding claims, characterized in that the spring-loaded locking mechanism ( 100 ) near the inlet nozzle ( 24 ) of the screw compressor ( 10 ) is arranged. Screw compressor ( 10 ) according to claim 4, characterized in that the spring-loaded locking mechanism ( 100 ) in a vent line from the relief valve ( 80 ) to the inlet nozzle ( 24 ) of the screw compressor ( 10 ) is arranged.

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