WO2018177821A1

WO2018177821A1 - Multistage compressor

Info

Publication number: WO2018177821A1
Application number: PCT/EP2018/057058
Authority: WO
Inventors: Günther MAYER
Original assignee: Mahle International Gmbh
Priority date: 2017-03-29
Filing date: 2018-03-20
Publication date: 2018-10-04
Also published as: US20200040879A1; EP3601800B1; DE102017205366A1; CN110462214A; EP3601800A1; CN110462214B

Abstract

The invention relates to a multistage compressor (1), comprising - at least one high-pressure stage (2) and at least one low-pressure stage (3), - at least two pistons (6) which are driven via a common crankshaft (8) mounted in a crankcase (7) and which are guided in corresponding cylinders (5), said pistons forming the at least one high-pressure stage (2) and the at least one low-pressure stage (3), and - a line assembly (9) which communicates with the individual cylinders (5) for supplying and discharging air to and from the cylinders (5), wherein - a switchable valve device (10) is arranged in the line assembly (9), said valve device being designed such that the high-pressure stage(s) (2) is/are paired with different cylinders (5) according to the switch position of the valve device (10).

Description

Multi-stage compressor

The present invention relates to a multi-stage compressor. The invention also relates to a compressor with such a multi-stage compressor and an operating method of such a multi-stage compressor.

Multi-stage compressors or multi-stage compressors are well known and usually have at least one low pressure stage and one high pressure stage, wherein the high pressure stage is exposed to increased wear and thereby often represents a weak point of such a multi-stage compressor.

Multistage compressors may, for example, have a plurality of piston-cylinder units, of which, for example, a piston-cylinder unit forms a high-pressure stage and a piston-cylinder unit forms a low-pressure stage. In the low-pressure stage, the gas to be compressed, for example air, is (pre-) compressed to a first pressure stage and then fed to the at least one second piston-cylinder unit, consequently the high-pressure stage. In between, of course, can still be a charge air cooler.

A disadvantage of the multistage compressors known from the prior art, however, is that, in particular, the piston rings in the high-pressure stage wear out more quickly due to the higher load, so that a failure of the multistage compressor can even occur due to a worn high-pressure stage even with properly working low-pressure stages. The present invention therefore addresses the problem of providing a multi-stage compressor which overcomes the disadvantages known from the prior art.

This problem is solved according to the invention by the subject matter of independent claim 1. Advantageous embodiments are the subject of the dependent claims.

The present invention is based on the general idea to provide a multi-stage compressor with at least one high-pressure stage and at least one low-pressure stage, which is switched in operation such that not only a single piston-cylinder unit constantly forms the high-pressure stage, but the high-pressure stage over all Piston-cylinder units migrate, whereby a uniform wear and thus a longer life can be achieved. For this purpose, a so-called "clocking" valve device is used, which, depending on the switching position, passes on the high-pressure stage at each cycle one position, that is, assigns to each subsequent piston-cylinder unit. The multistage compressor according to the invention has at least two pistons which are driven via a common crankshaft mounted in a crankcase and which are guided in associated cylinders of a respective piston-cylinder unit and which form the at least one high-pressure stage or the at least one low-pressure stage. Of course, a total of three or more piston-cylinder units can be provided, of which one each form a high-pressure stage and the two or more others each form the upstream low-pressure stages. In addition, provided is a communicating with the individual cylinders line arrangement for supplying and discharging air to and from the individual cylinders. According to the invention, in this line arrangement, the switchable valve device is arranged, which is designed such that the high-pressure stage is assigned to different cylinders depending on the switching position, in particular that the At least one high-pressure stage at each cylinder power stroke a cylinder or a piston-cylinder unit moves on.

In this case it is also conceivable, not with every working stroke, but e.g. only to change the high pressure stage every tenth stroke. That is, over a time interval t would still load all piston-cylinder units in the same way and therefore be worn. Likewise, a change of the high-pressure stage at each restart / start of the compressor is conceivable.

The valve device can be performed mechanically, electrically, pneumatically or in other ways. The inventive embodiment of the multi-stage compressor, it is possible to use piston-cylinder units with the same dimensions, where contrary, for example, in multi-stage compressor known from the prior art, a high-pressure stage is carried out in each case with a smaller volume. By now in the multi-stage compressor according to the invention for the first time the same dimensions standard parts can be used, which can reduce the variety of parts and thus also the storage and logistics costs and installation costs. Another advantage of the multi-stage compressor according to the invention is that it is still possible to provide high-density air through the traveling high-pressure stage, even if a piston-cylinder unit fails. This can be detected, for example, via corresponding sensors, whereupon a control of the multi-stage compressor no longer controls and skips the damaged or incorrectly operating piston-cylinder unit. In known from the prior art multistage compressors a failure such as the high-pressure stage always leads to failure of the entire compressor. In an advantageous development of the solution according to the invention, one of the at least one low-pressure stage downstream and the at least one high-pressure stage upstream Vorverdichtungskühler is provided. About such a precompression cooler, the thermal energy that is supplied to the air during compression, withdraw again, whereby a further compression is easily possible. Of course, a Hochverdichtungskühler the high-pressure stage be followed, for example, before the introduction of the now highly compressed charge air in a pressure accumulator, whereby the storage capacity can be increased.

In a further advantageous embodiment of the solution according to the invention, a high-pressure stage and three low-pressure stages are provided, as well as four on a common and mounted in a crankcase crankshaft driven piston, which are guided in associated cylinders in each associated piston-cylinder units and a high-pressure stage and three Form low pressure stages. Such a compressor can be driven, for example, by an electric motor. Of course, alternative embodiments of the multi-stage compressor according to the invention may also be considered, with for example a total of five, six or more compressor stages, of which e.g. two act as high pressure stages and the remaining as low pressure stages. Due to the fact that in the multi-stage compressor according to the invention all compressor stages, that is all piston-cylinder unit, have the same dimensions, almost any scaling is possible. If, for example, a higher volume flow is required, the number or volume of the compressor units can simply be increased.

The present invention is further based on the general idea of equipping a compressor, in particular an oil-free compressor, with an interconnection described in the previous paragraphs, whereby a per se long can be achieved vivid and reliable functioning, since the multi-stage compressor according to the invention not only wears less strong and thus longer-lasting, but purely theoretical with appropriate detection devices and sensors and control devices and the failure of at least one pressure level can easily compensate.

The present invention is further based on the general idea to provide an operating method of the above-described multi-stage compressor in which a switchable valve device is switched such that the high-pressure stage depending on the switching position of the valve device is assigned to different cylinders, in particular that the at least one high-pressure stage at each power stroke that is, in an up and down movement of an associated piston in an associated piston-cylinder unit, a cylinder moves on. Again, it is conceivable not at every stroke, but e.g. only to change the high pressure stage every tenth stroke. That is, over a time interval t would still load all piston-cylinder units in the same way and therefore be worn. Due to the continuous migration of the at least one high-pressure stage, the wear phenomena that have hitherto occurred in only a single piston-cylinder unit forming the high-pressure stage can now be uniformly distributed to all piston-cylinder units, as a result of which they wear out less and thus have a higher total for the compressor Life expectancy is achieved.

Other important features and advantages of the invention will become apparent from the dependent claims, from the drawings and from the associated figure description with reference to the drawings.

It is understood that the features mentioned above and those yet to be explained not only in the combination specified in each case, but which can be used in other combinations or alone, without departing from the scope of the present invention.

Preferred embodiments of the invention are illustrated in the drawings and will be described in more detail in the following description, wherein like reference numerals refer to the same or similar or functionally identical components.

Show, in each case schematically,

Fig. 1 is a sectional view through a multi-stage according to the invention

Compressor without further illustration of an associated valve device according to the invention,

2 shows an associated valve device in a first switching position,

3 shows a representation as in FIG. 2, with a valve device in a second switching position, FIG.

4 shows a possible embodiment of a valve body of the valve device,

5 shows an upper part of the valve body in the intake stroke,

Fig. 6 is a lower part of the valve body in the exhaust stroke.

According to FIGS. 1 to 3, an inventive multistage compressor 1 has at least one high-pressure stage 2 and at least one low-pressure stage 3. According to FIG. 2, the multi-stage compressor 1 according to the invention has a total of four pressure stages, one of which as a high-pressure stage 2 and three as Low pressure stages 3 are formed. Each pressure stage 2, 3 has its own piston-cylinder unit 4 with a cylinder 5 and a translationally displaceably mounted piston 6 therein, wherein the piston 6 via a common and in a crankcase 7 (see Fig. 1) mounted crankshaft are driven. Also provided is a communicating with the individual cylinders 5 line assembly 9 for supplying and discharging air to and from the cylinders 5. In the line assembly 9 (see, in particular, Figs 2 and 3), a switchable valve device 10 is arranged according to the invention, the is formed such that the high-pressure stage 2 is assigned depending on the switching position of a valve body 1 1 of the valve means 10 different cylinders 5 or is, in particular that the at least one high-pressure stage 2 at each power stroke of a piston 6 a cylinder 5 moves on. Alternatively, it is also conceivable not to change the high-pressure stage 2 at every power stroke, but only at every tenth power stroke, for example. That is, over a time interval t would still load all piston-cylinder units 4 in the same way and therefore also be worn.

According to FIG. 2, the valve device 10 is shown in an intake position, in which the low-pressure stages 3 suck in air from the crankcase 7 via the valve body 11 of the valve device 10. The suction can also be done directly from the ambient air or an interposed filter. Likewise, pre-compressed and cooled over the Vorverdichtungskühler 12 air is sucked and fed via the valve body 1 1 of the valve means 10 of the high-pressure stage 2, that is so the left above shown piston-cylinder unit 4 already in a previous cycle. In a next work cycle, in a thus subsequent rotation of the valve body 1 1 of the valve device 10 in a clockwise direction, the high-pressure stage 2 would go from top left to top right and in the same way the low pressure stages 3 to each piston-cylinder unit 4 in or against the clock be twisted. Of course, other movements of the valve body 1 1 are conceivable, for example, translational.

Looking at FIG. 3, one can see there an exhaust stroke, in which the now pre-compressed air from the three low-pressure stages 3 via the valve body 1 1 of the valve device 10 is supplied to the first precompression cooler 12. Likewise, in the high-pressure stage 2, highly compressed charge air is supplied via the valve body 11 of the valve device 10, for example to a second high-compression cooler 13 and / or finally to a pressure accumulator 14. By turning the valve body 1 1 clockwise or in the opposite direction is achieved with the valve device 10 and the associated line assembly 9 according to the invention a wandering of the respective high pressure stage 2 on the individual piston-cylinder units 4, whereby the increasingly occurring in the high-pressure stage 2 signs of wear evenly can be distributed to all piston-cylinder units 4 and whereby the life expectancy of the multi-stage compressor 1 according to the invention increases significantly.

According to FIG. 2, for the sake of clarity, only the inlet lines of the line arrangement 9 are shown in the respective piston-cylinder units 4, while according to FIG. 3 only the outlet lines are shown. Of course, however, the line arrangement 9 always has an inlet and outlet line to and from the respective piston-cylinder unit 4.

In the compressor 1 shown in FIGS. 2 and 3, a total of three low-pressure stages 3 and only one single high-pressure stage 2 are provided, it being understood that other low-pressure stages 3 or high-pressure stages 2 can be provided. The multi-stage compressor 1 according to the invention is operated in which the switchable valve device 10 is switched such that the high-pressure stage 2 is assigned to different cylinders 5, that is different piston-cylinder units 4, depending on the switching position, so that the at least one high-pressure stage 2 at Each working cycle of the piston 6 or at each switching cycle of the valve device 10 a cylinder 5 and a piston-cylinder unit 4 moves on. Alternatively, it is also conceivable not to change the high-pressure stage 2 at every power stroke, but only at every tenth power stroke, for example. That is, over a time interval t would still load all piston-cylinder units 4 in the same way and caused by the high-pressure stage 2 increased signs of wear can be applied evenly to all piston-cylinder units 4. The multi-stage compressor 1 according to the invention also has the great advantage that, for example, by the failure of a single low-pressure stage 3 can be turned off by detecting, for example by means of a corresponding control device, so that the multi-stage compressor 1 of the invention even in the event of failure of a single or more low-pressure stages. 3 or high-pressure stages 2 continues to work, since the high-pressure stage 2 is not bound to only one or at least fixed to each piston-cylinder units 4.

The valve device 10 has, according to FIG. 4, a rotatable cylindrical valve body 11 having an upper part 17 and a lower part 18 and may be pneumatically, electrically or hydraulically switchable. In this case, in the valve body 1 1 on the lateral surface of different inputs 15 and 16 outputs are arranged, which can also change their inlet function or outlet function depending on the switching position. Of course, the inputs 15 and the outputs 16 may also be arranged reversed. According to FIG. 5, an upper part 17 of the valve body 1 1 is shown in an intake position, in which the low-pressure stages 3 suck air from the crankcase 7 or from the environment, in particular via a filter device. In this case, an intake of air via three inputs 15a. The sucked air is supplied via the outputs 15a associated with the outputs 16a designed as a low-pressure stages 3 piston-cylinder units 4 and after the compression stroke the Vorverdichtungskühler 12. The term "precompression cooler 12" is based on the cooling after the low-pressure compression and before the high-pressure compression. Likewise, pre-compressed and cooled over the Vorverdichtungskühler 12 air is sucked through the input 15b and the valve body 1 1 of the valve means 10 and the input 15b associated output 16b of the high-pressure stage 2, that is so the above left piston Cylinder unit 4 supplied.

Looking at Fig. 6, one can see there a lower part 18 of the valve body 1 1 at an exhaust stroke, which runs simultaneously with the intake stroke of the upper part 17 and in which the now pre-compressed air from the three low-pressure stages 3 via the inputs 15 a and the associated outputs 16 a of the valve body 1 1 of the valve device 10 is supplied to the first precompression cooler 12. Likewise, in the high pressure stage 2 highly compressed charge air via the input 15b of the valve body 1 1 of the valve means 10 and the associated output 16b, for example, a second high-compression cooler 13 and / or finally fed to a pressure accumulator 14. By turning the valve body 1 1 clockwise or in the opposite direction is achieved with the valve device 10 and the associated line assembly 9 according to the invention a wandering of the respective high pressure stage 2 on the individual piston-cylinder units 4, whereby the increasingly occurring in the high-pressure stage 2 signs of wear evenly on all piston Cylinder units 4 can be distributed and whereby the life expectancy of the multi-stage compressor 1 according to the invention increases significantly.

The two parts 17, 18 are rotatable relative to each other or together. The intake stroke is controlled via the lower part 17. The exhaust stroke over the upper part 18, or vice versa. Both parts 17, 18 move simultaneously clockwise or counterclockwise to allow precise timing while maintaining a robust design. But there is no connection of the channels or

Fräessen between the upper part 17 and the lower part 18th

Can be driven, the crankshaft 8 and thus the multi-stage compressor 1, for example via an electric motor, not shown.

*****

Claims

claims

1 . Multi-stage compressor (1),

with at least one high-pressure stage (2) and at least one low-pressure stage (3),

- With at least two via a common and in a crankcase (7) mounted crankshaft (8) driven piston (6) which are guided in associated cylinders (5), and at least one high pressure stage (2) and the at least one low pressure stage ( 3) form,

- With a with the individual cylinders (5) communicating line arrangement (9) for supplying and discharging air to and from the cylinders (5),

- wherein in the line arrangement (9) a switchable valve device (10) is arranged, which is designed such that the at least one high-pressure stage (2) depending on the switching position of the valve device (10) is assigned to each different cylinders (5).

2. Compressor according to claim 1,

characterized in that

the at least one high-pressure stage (2) continues to move a cylinder (5) at each cylinder power stroke or shift position.

3. Compressor according to claim 1 or 2,

characterized in that

is formed during a time interval t of each of the piston-cylinder units (4) for an equal number of cylinder power strokes as a high pressure stage (2) and as a low pressure stage (3).

4. Compressor according to one of the preceding claims,

characterized in that

one of the at least one low-pressure stage (3) downstream and the at least one high-pressure stage (2) upstream Vorverdichtungskühler (12) is provided.

5. Compressor according to one of the preceding claims,

characterized in that

the valve device (10) has a rotatable cylindrical valve body (1 1).

6. Compressor according to one of claims 1 to 5,

characterized in that

the valve device (10) is pneumatically, electrically or hydraulically switchable.

7. A compressor according to any one of claims 1 to 6,

characterized in that

a high-pressure stage (2) and three low-pressure stages (3) are provided,

four pistons (6) driven by a common crankshaft (8) mounted in a crankcase (7) and located in associated cylinders (5); leads, and which form a high-pressure stage (2) and the three low-pressure stages (3).

8. A compressor (19), in particular an oil-free compressor, with a multi-stage compressor (1) according to one of the preceding claims.

9. Operating method of a multi-stage compressor (1) according to one of claims 1 to 6, wherein the switchable valve device (10) is switched such that the at least one high-pressure stage (2) depending on the switching position of the valve device (10) respectively different cylinders (5 ) is assigned, in particular that the at least one high-pressure stage (2) on each cylinder power stroke a cylinder (5) moves on.