EP2344767B1 - Compressor for producing compressed air for a motor vehicle - Google Patents

Description

The invention relates to a compressor for compressed air generation, in particular for a motor vehicle, with a dead space valve to relieve the compressor outside a compressed air delivery phase.

The invention further relates to a method for operating a compressor for generating compressed air, in particular for a motor vehicle, wherein a dead space valve is opened to relieve the compressor outside a compressed air delivery phase.

Compressors for generating compressed air can be relieved of pressure during an air supply phase, while the compressed air is fed into a system downstream of the compressor, in order to save energy. For this purpose, the compressor may include a dead space valve, which connects, for example, a closed dead space with a compression space of the compressor to allow breathing of the compressor in the dead space, or the compression space opens to the environment, to a non-pressurized conveying air into the environment to allow. To control and operate the dead space valve is doing, such as from the DE 39 09 531 A1 known, already used by the compressor compressed air. The AT 152 717 B also describes a reciprocating compressor, which can be relieved with the help of a switchable dead space. The dead space is switchable by a control valve which is electromagnetically controlled.

However, in order to relieve the compressor by means of compressed air, so a pneumatic switching medium, a relatively expensive piping between the compressor and the compressor in a delivery phase downstream compressed air conditioning system is necessary to return compressed air for actuating the dead space valve to the compressor.

The invention is therefore based on the object during the switching of Schadraumventils occurring mechanical loads of air inlet and outlet valves of the compressor to limit.

This object is achieved with the features of the independent claims.

Advantageous embodiments and modifications of the invention will become apparent from the dependent claims.

In the generic compressor is provided that the dead space valve is electrically actuated. By providing an electrical connection, via which the Schadraumventil is electrically actuated, can be dispensed with a complicated pipe guide for a pneumatic pressure medium, for example, processed compressed air. Compared to a pneumatically unloaded compressor, the structural complexity and the space required is reduced.

According to the invention it is provided that a relief hole is provided in a valve body of the dead space valve to relieve the valve body in each switching position of the dead space valve. If the valve body of Schadraumventils relieved in each switching position of Schadraumventils, that is, there are no resulting pressure-related forces on the valve body, the forces necessary for switching the dead space valve forces can be selected low, resulting in an electrical actuation of the dead space valve to a reduction of energy consumption , A pressure relief of the valve body is possible in particular with an electrical actuation of the dead space valve, because no control surfaces for transmitting power from an actuating medium to the valve body are necessary. Furthermore, the switching time of the dead space valve can be reduced in this way, whereby the undesirable mechanical loads occurring during switching of air inlet and outlet valves of the compressor are limited.

Usefully, it can be provided that the dead space valve comprises a lifting magnet and a coil. A combination of a solenoid with a coil for actuating the dead space valve is a mature and reliable way to realize an electrical controllability of Schadraumventils.

However, it is particularly preferred that the dead space valve comprises a piezoelectric actuator. The use of a piezoelectric actuator, which can be constructed, for example, from many individual piezocrystals, also allows the realization of an electrical controllability of the dead space valve. Depending on the design of the piezoelectric actuator, the valve body of the dead space valve can be held in its open or in its closed position solely by the piezoelectric actuator without any further components, in particular without a spring. This allows the construction of a particularly robust dead space valve, which also has very short switching times.

In the generic method it is provided that the dead space valve is electrically operated.

The invention is based on the generic method in that a valve body of Schadraumventils is relieved of pressure via a relief hole in each switching position of the dead space valve.

In this way, the advantages and particularities of the compressor according to the invention are also implemented in the context of a method.

Advantageously, it can be provided that upon actuation of the dead space valve, a change in current in a coil, a movement of a solenoid is induced.

It is particularly preferred that upon actuation of the dead space valve, a change in an electric field, a change in length of a piezoelectric actuator is induced.

The invention will now be described by way of example with reference to the accompanying drawings by way of particularly preferred embodiments.

Figur 1

ein Zylinderkopfgehäuse eines dem Stand der Technik entsprechenden Kompressors;

Figur 2

ein Zylinderkopfgehäuse eines erfindungsgemäßen Kompressors;

Figur 3

einen erfindungsgemäßen Doppelkompressor und

Figur 4

ein System aus einem Antriebsmotor, einem erfindungsgemäßen Kompressor und einer Druckluftaufbereitungsanlage.

Show it:

FIG. 1

a cylinder head housing of a compressor according to the prior art;

FIG. 2

a cylinder head housing of a compressor according to the invention;

FIG. 3

a double compressor according to the invention and

FIG. 4

a system of a drive motor, a compressor according to the invention and a compressed air treatment plant.

In the following drawings, like reference characters designate like or similar parts.

FIG. 1 shows a cylinder head housing of a compressor according to the prior art. The illustrated cylinder head housing 38 is connected via a connecting plate 44 with a housing, not shown, a piston chamber of the compressor. The cylinder head housing 38 has an air inlet 28 and an air outlet 30, through which air is sucked in or ejected during a compressed air delivery phase of the compressor. Furthermore, a dead space 40 and a dead space valve 12 are arranged with a valve body 14 in the cylinder head housing 38, wherein the dead space valve 12 is designed as a pneumatically actuated lift valve. In the illustrated switching position of the dead space valve 12, the valve body 14 of the dead space valve 12 separates the Dead space 40 of a piston chamber of the compressor, not shown, wherein the valve body 14 is seated tightly on a valve seat in the connection plate 44. The air is therefore expelled through an air outlet valve 42 and the air outlet 30 during a compression phase.

FIG. 2 shows a cylinder head housing of a compressor according to the invention. In contrast to FIG. 1 is that in FIG. 2 illustrated Schadraumventil 12 shown in its open switching state, so that the valve body 14 is not seated on its valve seat in the connection plate 44 and the compressor breathes in the dead space 40, wherein neither air sucked through the air inlet 28 is still discharged through the air outlet 30. In contrast to FIG. 1 is that in FIG. 2 illustrated Schadraumventil 12 actuated via an electrical connection 36, wherein a coil 20 of Schadraumventils 12 induces a magnetic field, so that a arranged in the interior of the coil 20 solenoid 18 is moved in the axial direction of Schadraumventils 12 and the Schadraumventil 12 opens or closes. The valve body 14 is guided by a guide ring 46, which can also perform a sealing function. Via a spring 70, the valve body 14 is biased, so that the dead space valve 12 is usually closed in the de-energized state. The valve body 14 furthermore has relief bores 16, by means of which it is ensured that no resulting pressure forces in the axial direction can act on the valve body 14. Therefore, the spring 70 need not be configured to hold the valve body 14 in its closed shift position when a maximum compression pressure in the piston space of the compressor is achieved. Therefore, the necessary for switching the dead space valve 12 force can be relatively small and, for example, about 20 N amount. In order to produce an efficiently working Schadraumventil 12, a holding current reduction can continue to be provided, which reduces the energy consumption of Schadraumventils 12 in its controlled switching state.

FIG. 3 shows a double compressor according to the invention. The illustrated double compressor 10 is arranged in a housing 32 which has a piston chamber 26 and a further piston chamber 26 ', in which in each case a piston 24 or a further piston 24' periodically move up and down, wherein both pistons 24, 24 'are driven by a common shaft 34. During a compressed air delivery phase, not shown, air is sucked in via an air inlet 28 and a further air inlet 28 'into the piston chamber 26 or the further piston chamber 26', compressed and expelled via a common air outlet 30. The illustrated compressor 10 further comprises a dead space valve 12, which valve body 14 which can connect outside of a compressed air delivery phase between the piston chamber 26 and the other piston chamber 26 '. The described dead space valve 12 can be actuated via the electrical connection 36, and comprises a piezoelectric actuator 22, which can be constructed, for example, from many individual piezoelectric elements which undergo a change in length when an electrical voltage is applied, so that the valve bodies 14 are movable in the direction of this change in length. Since the individual Piezzoelelmente are usually crystals which have a high compressive strength, can be dispensed with a separate spring for biasing the valve body 14 in this embodiment. It is also a dead space valve 12 analogous to the in FIG. 2 embodiment shown conceivable, either for each valve body 14 either a separate coil may be provided with a solenoid or both valve body 14 are movable via a common solenoid from a common coil. In an analogous manner can also in the embodiment according to FIG. 2 a piezoelectric actuator may be provided instead of the combination of coil and solenoid.

The illustrated embodiments of the compressors according to the invention are to be understood only as examples. In particular, the valve body 14 can also be realized in the form of a sliding lamella, as for example from the DE 39 09 531 A1 is known.

FIG. 4 shows a system of a drive motor, a compressor according to the invention and a compressed air treatment plant. The illustrated drive motor 48 drives via a drive train to the compressor 10, which in turn supplies compressed air via a cooling line 52 to a compressed air treatment plant 54, which distributes the compressed air to a first load circuit 56, a second load circuit 58 and a third load circuit 60. The control of the compressor 10 and the compressed air treatment system 54 is controlled by a control unit 50, which determines the sensors relevant to the control via sensors 62, 64, 66 and 68. The cooling line 52 serves to cool the still highly heated compressed air generated by the compressor 10 to a temperature which, for example, is smaller by 5 ° C. than the maximum temperature of about 80 ° C. permissible for efficient drying. In addition to the dead space valve, which is indicated in this illustration only on the compressor 10, a clutch may also be provided, wherein the control of the clutch can then be synchronized, for example, with the control of the dead space valve.

The features of the invention disclosed in the foregoing description, in the drawings and in the claims may be essential to the realization of the invention both individually and in any combination.

LIST OF REFERENCE NUMBERS

10

compressor

12

Clearance volume valve

14

valve body

16

relief well

18

solenoid

20

Kitchen sink

22

Piezzoaktor

24

piston

24 '

another piston

26

piston chamber

26 '

another piston chamber

28

air intake

28 '

additional air intake

30

air outlet

32

casing

34

wave

36

electrical connection

38

Cylinder head housing

40

dead space

42

air release

44

connecting plate

46

guide ring

48

drive motor

50

control unit

52

cooling line

54

Compressed air treatment plant

56

first consumer circle

58

second consumer circuit

60

third consumer circle

62

sensor

64

sensor

66

sensor

68

sensor

70

feather

Claims (6)

1. Compressor (10) for producing compressed air for a motor vehicle, comprising air inlet and air outlet valves and an electrically actuable dead space valve (12) for relieving the compressor (10) outside a compressed air delivery phase, characterised in that a relief hole (16) is provided in a valve body (14) of the dead space valve (12) for pressure-relieving the valve body (14) in each switching position of the dead space valve (12).
2. Compressor (10) according to claim 1, characterised in that the dead space valve (12) comprises a solenoid (18) and a coil (20)
3. Compressor (10) according to claim 1, characterised in that the dead space valve (12) comprises a piezoelectric actuator (22).
4. Method for operating a compressor according to claim 1, wherein, for relieving the compressor (10) outside a compressed air delivery phase, an electrically actuated dead space valve (12) is opened, characterised in that a valve body (14) of the dead space valve (12) is pressure-relieved in every switching position of the dead space valve (12) via a relief hole (16).
5. Method according to claim 4, characterised in that a current change in a coil (20) induces a movement of a solenoid (18) on the actuation of the dead space valve (12).
6. Method according to claim 4 or 5, characterised in that a change of an electric field induces a positional change of e piezoelectric actuator (22) on the actuation of the dead space valve (12).

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