DE102016105148A1 - Piston compressor with closing device for the outlet line - Google Patents

Abstract

Piston compressor for compressing a gas, which is optionally separable by means of a coupling of a drive device. The reciprocating compressor has an intake valve disposed between a gas to be compressed inlet line and a compression space of the reciprocating compressor, and an exhaust valve disposed between the compression space of the reciprocating compressor and a compressed gas discharge line. Furthermore, the piston compressor has a closing device which closes the outlet line with respect to the compression space.

Description

The invention relates to a piston compressor for compressing a gas, which is optionally separable by means of a coupling of a drive device, with an inlet valve which is arranged between an inlet line for gas to be compressed and a compression chamber of the piston compressor and an outlet valve, which between the compression chamber of the piston compressor and a compressed gas outlet pipe.

Such compressors are used for example for the compressed air supply of commercial vehicles, in particular for the compressed air supply of the brake system. The drive of the compressor is carried out via the drive train of the internal combustion engine. There are known applications in which between the compressor and the drive connection, a clutch is arranged to separate the compressor from the drive when the compressed air system of the commercial vehicle is filled with compressed air. In known embodiments, the discharge line of the compressor is emptied simultaneously with the opening of the clutch. When restarting the compressor, the pressure in the then pressure-free outlet line must first be rebuilt before compressed air can be supplied to the compressed air system. To avoid such efficiency losses, solutions are also known in which the outlet line is not switched pressure-free, while the reciprocating compressor is not driven.

In reciprocating compressors of the type mentioned there is the danger that an exhaust valve is leaking due to contamination such as deposits by lubricating oil residues or in particular of such dissolved particles. In this case, the exhaust valves often have a valve tongue, between which and the valve seat such contaminants can get there and prevent the complete closing of the valve. For example, in the event of a leakage of an exhaust valve resulting therefrom in conjunction with a pressurized exhaust line during separation of the compressor from the engine, compressed air may return to the compression space of the compressor. The pressure in the compression chamber of a reciprocating compressor in a 12.5 bar system can then rise to up to 6 bar. When restarting the reciprocating compressor with such a high pressure in the compression chamber results in the first compression stroke of the piston, a compression of the gas in the compression chamber up to about 60 bar. The torque occurring here is far too high for the clutch, which slips in this case, overheated and excessively excessive wear. In addition, such a high pressure in the compression chamber can also lead to damage to the compressor itself.

The invention is therefore based on the object to provide an improved reciprocating compressor, which avoids the aforementioned disadvantages and the resulting undesirable effects.

To solve this problem, a reciprocating compressor according to claim 1 and a method for operating a reciprocating compressor according to claim 8 is proposed. Further developments of the reciprocating compressor and the method are the subject of the dependent claims.

To solve the problem, a piston compressor for compressing a gas is proposed, which is optionally separable by means of a coupling of a drive device, with an inlet valve which is arranged between an inlet line for gas to be compressed and a compression chamber of the reciprocating compressor and an outlet valve, which between the Compression space of the reciprocating compressor and a discharge line for compressed gas is arranged. The reciprocating compressor has a separate closing device arranged behind the outlet valve in the flow direction of the gas, by means of which the outlet line can be closed off during the separation of the reciprocating compressor from the drive device with respect to the compression space.

Such a reciprocating compressor has an inlet line, which is in particular part of an inlet system and through which a gas to be compressed is guided to a compression space of the reciprocating compressor. In this case, an inlet valve is arranged between the inlet line and the compression space, which during the intake of gas to be compressed into the compression space (the pressure in Compaction space is less than the pressure in the inlet line) is open. During the compression of the gas in the compression space (the pressure in the compression space is higher than the pressure in the intake pipe), the intake valve closes the compression space opposite to the intake pipe.

Between the compression space and the outlet conduit, an outlet valve is arranged which is open when the compressed gas is expelled from the compression space (the pressure in the compression space is higher than the pressure in the outlet conduit), thus defining a connection between the compression space and the outlet conduit. The exhaust valve closes the connection between the compression space and the outlet line during the suction of gas to be compressed into the compression space (the pressure in the compression space is lower than the pressure in the outlet line) to prevent backflow of compressed gas from the discharge line into the compression space.

Both intake and exhaust valves of reciprocating compressors often employ valves having a closing body that is forced against the valve seat depending on the pressure difference on either side of the valve thereby closing or lifting the valve from the valve seat, thereby opening the valve , A common type of such valves has a serving as a closing body valve tongue. However, it is also known for piston compressors to use inlet and outlet valves, which have switched valve bodies.

The piston compressor according to the invention has a separate closing device arranged behind the outlet valve in the flow direction of the gas. This locking device is designed so that it is suitable for the particular gas-tight closing of the outlet to the exhaust valve out. A return flow of compressed gas from the outlet line back into the compression chamber through a possibly not reliably closed exhaust valve can thus be prevented by the closed locking device. The closing device is a separate device relative to the outlet valve, which is arranged independently of the outlet valve and is not in operative connection with it. The closing device is arranged in particular adjacent to the outlet valve at the beginning of the outlet line facing the compression chamber. A risk of backflow of pressurized, compressed gas from the discharge line back into the compression space exists especially during a separation of the reciprocating compressor from the drive device and in particular when the outlet line is filled. Therefore, in particular during the separation of the piston compressor from the drive device by means of the closing device, the outlet line can be closed off from the compression space. This prevents pressurized compressed gas during a separation of the piston compressor from the drive device in particular passes through an incomplete closing exhaust valve from the outlet line back into the compression space and there can cause an increase in pressure with the consequences described above.

In one embodiment of the reciprocating compressor, the closing device closes the outlet line depending on the pressure difference applied to both sides of the closing device. The closing device is designed so that it closes when the pressure in the outlet in the flow direction of the gas after the closing device is higher than the pressure in the outlet before the closing device, ie in the direction of the compression chamber of the reciprocating compressor. This is especially the case when the exhaust valve does not close reliably, so that compressed gas from the exhaust pipe can flow back into the compression space. In this case, a pressure drop occurs on the side of the closing device facing the compression chamber, which then leads to closing of the closing device.

In one embodiment of the reciprocating compressor, a check valve forms the closing device. Check valves also switch depending on the applied pressure difference on both sides of the check valve. In check valves, the closing element is usually biased so that the valve remains closed at the same pressure on both sides of the valve or one to a compensatable by the bias pressure difference. To open a check valve, therefore, a pressure difference between the two sides of the valve is required, as is present in particular during the compression operation of the reciprocating compressor. As soon as the reciprocating compressor is no longer driven-in particular during a separation of the reciprocating compressor from the drive device-there is no longer sufficient pressure difference at the stop valve, so that the stop valve closes the outlet line with respect to the compression chamber. A suitable type of stop valve suitable for the present purpose is a check valve.

In one embodiment of the reciprocating compressor, a switchable valve device forms the closing device. In this embodiment, the switching position of the closing device is freely controllable, in particular depending on various parameters, such as depending on the switching state of the coupling between the drive device and the reciprocating compressor or depending on the pressure difference between the compressed gas system and the compression chamber.

In one embodiment of this piston compressor, the switchable closing device is designed so that it can be switched simultaneously with the opening of the clutch in a closed position. A circuit of the closure device simultaneously with the opening of the clutch in a closed position offers the advantage that the outlet line is always completed with respect to the compression chamber as soon as the reciprocating compressor is not driven. In this way, the risk of unrecognized leakage of compressed gas back into the compression chamber in non-driven reciprocating compressor can be prevented with the negative effects described above, since in this embodiment, the outlet when open Clutch is closed regardless of leakage of the exhaust valve.

In one embodiment of this reciprocating compressor, a 2/2-way valve forms the switchable valve device. Such a valve represents a convenient and reliable embodiment of a switchable locking device.

An embodiment of the reciprocating compressor has a control device which is signal-connected both with the coupling and with the switchable valve device. Such a control device may be formed by the control device of the compressed gas system, which takes over the control of the switchable valve device with. Alternatively, it is also possible that the reciprocating compressor for this purpose has a separate from the control device of the compressed gas system control device which serves to switch the closing device.

To solve the problem, a method for operating a reciprocating compressor for compressing a gas is also proposed. The piston compressor is optionally separable by means of a clutch of a drive device, and has an inlet valve, which is arranged between an inlet line for gas to be compressed and a compression chamber of the piston compressor and has an outlet valve which between the compression chamber of the piston compressor and an outlet for compressed gas is arranged. Furthermore, the piston compressor has a separate switchable closing device arranged downstream of the outlet valve in the flow direction of the gas, by means of which the outlet line can be closed off during the separation of the piston compressor from the drive device with respect to the compression chamber, and a control device which can be connected to both the clutch and the switchable Valve device is signal connected. In the method for operating the reciprocating compressor, the control device switches the switchable valve device into a closed position when the coupling between the reciprocating compressor and the drive device is open.

Characterized in that the closing device is switched with the clutch open between the reciprocating compressor and the drive means in a closed position, the outlet line to the compression chamber with non-driven piston compressor is always completed. In this way, even in the case of a non-reliably closing exhaust valve no compressed gas can go back into the compression chamber with non-driven piston compressor and cause the negative effects described above.

In one embodiment of the method for operating a reciprocating compressor, the control device switches the switchable valve device into an open position when the coupling between the reciprocating compressor and the drive device is closed. This process step ensures that the outlet line is always open with respect to the compression chamber of the reciprocating compressor as soon as the reciprocating compressor is driven in order to prevent the build-up of a backpressure at the outlet with respect to the compression chamber, which has a negative effect on the compression output of the reciprocating compressor or even to one Damage to the piston compressor and / or the clutch could result.

In one embodiment of the reciprocating compressor, which is operated by the proposed method, the closing device is designed so that it can be switched simultaneously with the opening of the clutch in a closed position. The switchable closing device can be formed for example by a 2/2-way valve.

Further advantages, features and applications of the present invention will become apparent from the following description taken in conjunction with the figures.

In the figures show:

1 a schematic representation of an exemplary piston compressor of the prior art;

2 a representation of an exemplary exhaust valve as used in piston compressors in the prior art;

3 a schematic representation of a first exemplary embodiment of a piston compressor according to the invention, in which a check valve forms the locking device; and

4 a schematic representation of a second exemplary embodiment of a piston compressor according to the invention, in which a switchable valve device forms the closing device.

1 shows a schematic representation of an exemplary reciprocating compressor 10 as known in the art. The crankshaft 11 of the reciprocating compressor 10 is about a clutch 3 with a drive device (not shown, here an internal combustion engine) connected and by means of the coupling 3 optionally separable from this drive device. With the clutch open 3 Thus, no torque is applied to the crankshaft 11 of the reciprocating compressor 10 transfer, so that the crankshaft 11 during the separation of the reciprocating compressor 10 from the drive device stands still.

The crankshaft 11 is with an eccentrically mounted connecting rod 12 connected to which a piston 13 is stored. The piston 13 is axially movable in a cylinder 14 of the reciprocating compressor 10 stored. The at least one crankshaft 11 , a connecting rod 12 and a piston 13 having crank mechanism 15 is in a crankcase 16 arranged, which firmly with the cylinder 14 connected is. By a rotary motion of the crankshaft 11 becomes the piston 13 from the connecting rod 12 so in the cylinder 14 moves that it performs a lifting movement.

Above the piston 13 is the cylinder 14 through a valve plate 20 locked. This defines the cylinder 14 , The piston 13 and the valve plate 20 the compression space 17 in the cylinder 14 , At the valve plate 20 is an inlet valve 21 arranged between an inlet pipe 22 and the compression room 17 is arranged. The inlet pipe 22 is part of an intake system 23 , the fresh air from the environment through a filter (not shown) sucks and the inlet line 22 through the cylinder head (not shown) the compression space 17 supplies. The cylinder head is above the valve plate 20 arranged and has a cylinder head volume 24 on, which via the inlet valve 21 with the compression space 17 communicates. The inlet valve 21 is designed as a check valve, which is a suction of fresh air in the compression chamber 17 allows, but a back flow over the inlet line 22 in the compression room 17 sucked air prevented.

At the valve plate 20 is also an exhaust valve 26 arranged between the compression space 17 and an outlet conduit 27 is arranged. Via the outlet pipe 27 is compressed gas, here air, fed to a compressed air storage, not shown here. The outlet valve prevents this 26 , which is also designed as a check valve, a back flow of compressed air from the outlet pipe 27 in the compression room 17 ,

2 shows a representation of an exemplary exhaust valve 26 as in piston compressors 10 is commonly used in the art. The outlet valve 26 is on the valve plate 20 of the reciprocating compressor 10 above the compression chamber 17 arranged. The valve plate 20 has an outlet opening 28 on which the compression space 17 with one in valve plate 20 and cylinder head of the reciprocating compressor 10 arranged cylinder head volume 27a connects, which with the outlet 27 connected is.

The outlet valve 26 has a valve tongue as a valve body 26a which, starting from a predetermined pressure difference between the compression space 17 and the outlet pipe 27 from the valve seat 26b releases and a flow of air from the compression chamber 17 in the outlet pipe 27 allows. The outlet valve 26 also has a above the outlet opening 28 arranged investment element 26c on, on which the valve tongue 26a in the open state is present. Once the valve tongue 26a from the valve seat 26b releases the pressurized air from the compression chamber 17 through the lateral open areas on the valve tongue 26a and the contact element 26c past the outlet pipe 27 stream.

Get impurities out of the compression chamber 17 or from the cylinder head volume 27a , for example, of forming deposits by residues in the air flowing through the hot top of the piston 13 , the valve plate 20 or the cylinder head volume 27a release, between the valve tongue 26a and the valve seat 26b , there is a risk that the exhaust valve 26 no longer completely closes. In this case, compressed air may be discharged from the outlet pipe 27 in the compression room 17 flow back as soon as the pressure in the compression chamber 17 under the pressure in the outlet pipe 27 sinks. In a 12.5 bar compressed air system of a commercial vehicle, the compression chamber 17 of the reciprocating compressor 10 For example, be acted upon by the back-flowing air at a pressure of up to 6 bar. Will the piston compressor 10 then reconnected to the drive means, the piston compressor generates 10 at the first stroke an internal pressure of up to 60 bar. Unless the compression space 17 withstand this enormous internal pressure, this is on the crankshaft 11 resulting torque for the clutch 3 usually much too high, so that it slips, overheats and excessively fast wears.

3 shows a schematic representation of a first exemplary embodiment of a piston compressor according to the invention 10 , The construction of the reciprocating compressor 10 in 3 corresponds largely to the structure of in 1 shown and described for this purpose piston compressor 10 , so that same elements of the reciprocating compressors 10 be denoted by the same reference numerals. Below are just the differences of the reciprocating compressor 10 out 3 opposite the piston compressor 10 out 1 explained.

The in 3 illustrated piston compressor 10 has a closing device in the form of a check valve, which downstream of the outlet valve 26 is arranged separately. The check valve is as a check valve 31 formed with biased valve body. This check valve 31 then opens when the pressure from the piston compressor 10 expelled air from the compression chamber 17 through the outlet valve 26 flows to an amount higher than the pressure of the air, which is in the outlet pipe 27 located. The amount of pressure difference is at least so great that the bias of the check valve 31 is overcome, so the check valve 31 opens.

During standstill of the reciprocating compressor 10 there is no compressed air in the compression chamber 17 , Even if the exhaust valve 26 can not reliably close, can no compressed air from the pressurized outlet pipe 27 back to the compression room 17 flow as the outlet line through the check valve 31 opposite the compression chamber 17 is completed. In the compression mode of the reciprocating compressor 10 becomes compressed air, which is under a higher pressure than the compressed air in the outlet pipe 27 through the outlet valve 26 promoted. Due to the pressure difference from the compression chamber 17 discharged air against the pressure in the outlet pipe 27 the check valve opens 31 , and the compressed air becomes the outlet pipe 27 and thus supplied to the compressed air system.

4 shows a schematic representation of a second exemplary embodiment of a piston compressor according to the invention 10 , Also the construction of the piston compressor 10 in 4 corresponds largely to the structure of in 1 shown and described for this purpose piston compressor 10 , so that same elements of the reciprocating compressors 10 be denoted by the same reference numerals. Below are just the differences of the reciprocating compressor 10 out 4 opposite the piston compressor 10 out 1 explained.

The in 4 illustrated piston compressor 10 has a closing device in the form of a switchable valve device 32 on, in the flow direction behind the exhaust valve 26 is arranged separately. The switchable valve device 32 is executed in the exemplary embodiment as a 2/2-way valve, which is switchable from a closed position to the illustrated open position. The switchable valve device 32 is via a control line 32a with a control device 33 connected, which is the switchable valve device 32 via via the control line 32a transmitted switching signals opens and closes. The control device 33 In the exemplary embodiment, it is also over a control line 3a with the clutch 3 connected, via the control line 3a Signals relating to the switching position of the clutch 3 to the controller 33 be transmitted. Optionally, the control device 33 via a control line 33a connected to the control of the compressed air system.

During standstill of the reciprocating compressor 10 - The coupling between the drive device and the reciprocating compressor 10 is open - is the switchable valve device 32 switched to the closed position. Even if the exhaust valve 26 can not reliably close, can no compressed air from the pressurized outlet pipe 27 back to the compression room 17 flow as the outlet pipe 27 in the closed position of the switchable valve device 32 opposite the compression chamber 17 is completed. When closing the clutch 3 at the beginning of the compression operation of the reciprocating compressor 10 becomes the switchable valve device 32 in the in 4 shown open position switched. This allows compressed air that is under a higher pressure than the compressed air in the outlet pipe 27 , through the exhaust valve 26 and by the switchable valve device located in the open position 32 in the outlet pipe 27 be promoted and supplied to the compressed air system. Optionally, in a variant in which the control device 33 connected to the control of the compressed air system, the opening of the clutch 3 simultaneously with the switching of the switchable valve device 32 in the closed position and the closing of the clutch 3 simultaneously with the switching of the switchable valve device 32 done in the open position.

LIST OF REFERENCE NUMBERS

3

clutch

3a

control line

10

piston compressor

11

crankshaft

12

pleuel

13

piston

14

cylinder

15

crankshaft

16

crankcase

17

compression chamber

20

valve plate

21

intake valve

22

inlet line

23

intake system

24

Cylinder head volume (inlet)

26

outlet valve

26a

valve tongue

26b

valve seat

26c

contact element

27

outlet pipe

28

outlet

31

check valve

32

switchable valve device

32a

control line

33

control device

33a

control line

Claims (9)

Piston compressor for compressing a gas, optionally by means of a coupling ( 3 ) is separable from a drive device, with an inlet valve ( 21 ), which between an inlet line ( 22 ) for gas to be compressed and a compression chamber ( 17 ) of the reciprocating compressor ( 10 ) is arranged and an exhaust valve ( 26 ), which between the compression space ( 17 ) of the reciprocating compressor ( 10 ) and an outlet line ( 27 ) is arranged for compressed gas, characterized in that the piston compressor ( 10 ) one in the flow direction of the gas behind the outlet valve ( 26 ) arranged separate locking device ( 31 . 32 ), by means of which the outlet line ( 27 ) during the separation of the reciprocating compressor ( 10 ) from the drive device with respect to the compression space ( 17 ) is lockable. Piston compressor according to claim 1, characterized in that the closing device ( 31 ) the outlet pipe ( 27 ) depending on the on both sides of the locking device ( 31 ) adjoining pressure difference closes. Piston compressor according to one of the preceding claims, characterized in that a check valve ( 31 ) forms the locking device. Piston compressor according to claim 1, characterized in that a switchable valve device ( 32 ) forms the locking device. Piston compressor according to claim 4, characterized in that the switchable closing device ( 32 ) is designed so that this simultaneously with the opening of the clutch ( 3 ) is switchable in a closed position. Piston compressor according to claim 4 or 5, characterized in that a 2/2-way valve, the switchable valve device ( 32 ). Piston compressor according to one of claims 1 or 4 to 6, characterized by a control device ( 33 ), which both with the clutch ( 3 ) as well as with the switchable valve device ( 32 ) is signal-connected. Method for operating a piston compressor according to claim 7, characterized in that the control device ( 33 ) the switchable valve device ( 32 ) then switches to a closed position when the clutch ( 3 ) between the piston compressor ( 10 ) and the drive device is open. Method for operating a reciprocating compressor according to claim 8, characterized in that the control device ( 33 ) the switchable valve device ( 32 ) then switches to an open position when the clutch ( 3 ) between the piston compressor ( 10 ) and the drive device is closed.

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