EP3408536A1

EP3408536A1 - Piston compressor having a venting device

Info

Publication number: EP3408536A1
Application number: EP17701320.8A
Authority: EP
Inventors: Gilles Hebrard; Wolfgang Kiener; Jean-Baptiste Marescot; Jörg MELLAR; Michel Saintive; Thomas Weinhold
Original assignee: Knorr Bremse Systeme fuer Nutzfahrzeuge GmbH
Current assignee: Knorr Bremse Systeme fuer Nutzfahrzeuge GmbH
Priority date: 2016-01-27
Filing date: 2017-01-24
Publication date: 2018-12-05
Anticipated expiration: 2037-01-24
Also published as: EP3408536B1; WO2017129553A1; CN108884820B; BR112018015262A2; CN108884820A; JP2019503453A; DE102016201208A1; DE102016201208B4; KR20180105211A; US20180372087A1

Abstract

The invention relates to a piston compressor for compressing a gas, which optionally can be disconnected from a drive device by means of a clutch. The piston compressor 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 an outlet valve, which is arranged between the compression chamber of the piston compressor and an outlet line for compressed gas. Furthermore, the piston compressor has a venting device, by means of which compressed gas can be led out of the compression chamber.

Description

PISTON COMPRESSO WITH BLEEDING DEVICE

The invention relates to a piston compressor for compressing a gas, which is optionally separable by means of a clutch from 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

Piston compressor and a discharge line for compressed gas is arranged.

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 a risk that an exhaust valve through

Contaminants such as deposits by lubricating oil residues or especially of such dissolved particles is leaking. 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 Compression chamber results in the first compression stroke of the piston, a compression of the gas in the compression chamber 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 the aforementioned disadvantages and the resulting undesirable

Avoids effects. To solve this problem, a reciprocating compressor according to claim 1 is proposed.

Further developments of the reciprocating compressor 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 clutch of a drive device, with an inlet valve, which between an inlet line for gas to be compressed and a compression space of

Piston compressor is arranged and an exhaust valve, which is arranged between the compression chamber of the reciprocating compressor and a discharge line for compressed gas. Of the

Piston compressor has a venting device through which compressed gas from the compression space can be discharged, which during the separation of the reciprocating compressor of the

Drive device from the outlet line passes back into 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 is open during the intake of gas to be compressed into the compression space (the pressure in the compression space is lower than the pressure in the inlet line). 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 line, an outlet valve is arranged, which is open when the compressed gas is expelled from the compression space (the pressure in

Compression space is higher than the pressure in the outlet pipe) and so a connection between the Compression space and the outlet defined. 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 with a closing body that is forced onto the valve seat depending on the pressure difference on either side of the valve and thereby closes or lifts off the valve seat, thereby opening the valve. A common type of such valves has a serving as a closing body valve tongue.

The piston compressor according to the invention has a venting device, through which compressed gas from the compression chamber can be discharged in order to lower the pressure therein. In this case, in particular compressed gas is discharged, which passes during a separation of the reciprocating compressor of the drive device in particular by a not completely closing exhaust valve from the pressurized outlet line back into the compression space and there a

Pressure increase caused.

In one embodiment of the reciprocating compressor, the compressed gas is by means of

Venting device from the compression chamber into a region of lower pressure,

in particular ambient pressure dissipated. Thus, the compressed gas can escape into a region which has a lower pressure than the compression space, in which compressed gas has penetrated from the outlet line. As a result of the discharge of the compressed gas, the pressure in the compression chamber decreases. In one embodiment of the reciprocating compressor, the region is formed with the ambient pressure from the environment itself, a gas space connected to the inlet system or the inlet line or the interior of the crankcase of the reciprocating compressor. An area with ambient pressure in the inlet system can be, for example, the inlet line or a gas space connected to it, which is formed, for example, in the cylinder head of the piston compressor and thus also forms part of the inlet line. In an embodiment in which the area is formed with the ambient pressure from the interior of the crankcase of the reciprocating compressor, which is characterized by the

Venting device from the compression chamber of the reciprocating compressor gas flowing into the Crankcase out where in particular first takes place a pressure equalization in the crankcase and then via the venting system with the environment.

In this case, both in a gas space connected to the inlet system and in the

Crankcase of the reciprocating compressor pressure fluctuations occur: in the intake system in particular depending on the Frischgasansaugung - for example, when the intake system is in communication with the intake system of a correspondingly large-sized engine - or due in particular previous crank drive movements in the crankcase. However, since both the intake system and the crankcase are in communication with the environment and there is usually a constant balance of pressure fluctuations with the environment, the pressure prevailing in a gas space connected to the intake system or in the crankcase in the context of this invention is considered as ambient pressure ,

In one embodiment of the reciprocating compressor, a switchable valve device forms the

Venting device by means of which compressed gas from the compression space can be discharged by a connection of the compression chamber with a region of lower pressure, in particular ambient pressure can be produced.

It may be a switchable valve device, by means of which a

For example, in the valve plate or in the cylinder wall arranged vent opening of the compression chamber of the reciprocating compressor is optionally connectable to a region of lower pressure, in particular ambient pressure. For this purpose, in particular a 2/2-way valve can be used which, for example, is so switchable that it opens and closes in particular parallel or offset with the actuation of the clutch and thus enables a pressure equalization in the compression chamber by the discharge of compressed gas, as long as the Piston compressor is not driven. However, it can also be provided to also switch such a valve device dependent on other parameters, such as, for example, the pressure actually prevailing in the compression chamber, which pressure is detected by pressure sensors connected thereto or in another suitable manner. Another embodiment of the reciprocating compressor has a pilot-operated check valve, which also assumes the function of the intake valve. Such a pilot-operated check valve represents a switchable valve device which is located between the inlet line and the compression chamber of the compressor is arranged and the connection between the inlet line and the compression chamber in particular automatically opens and closes according to the function of an inlet valve. In addition, such a pilot-operated check valve is a switchable valve device, by means of which the connection between the inlet line and the compression chamber is optionally openable and closable in order to allow pressure reduction by discharging compressed gas from the compression chamber.

For example, such a releasable check valve as well as the previously described switching valve in parallel or offset from the clutch operation switchable or in response to other, in particular with the pressure in the compression chamber related parameters, which are detected for example by means of sensors. With an opening of the inlet valve in the form of a pilot-operated check valve during a standstill of the compressor, a pressure equalization between the compression chamber and the inlet system take place, so that no significant pressure build-up can take place in the compression chamber.

In a further embodiment of the reciprocating compressor forms a check valve

Venting device by means of which compressed gas from the compression space can be discharged. Such a check valve is particularly designed so that it then opens and the

Compression chamber with a region of lower pressure, in particular ambient pressure connects, when the pressure in the compression chamber due to a compressed during a separation of the piston compressor from the drive device from the discharge line back into the compression chamber compressed gas during a first compression stroke increases so much that damage to the piston compressor or a device connected to the reciprocating compressor threatens. In this case, the check valve establishes a connection of the compression space with a region of lower pressure, in particular ambient pressure, whereby the compressed gas, which has passed from the outlet line back into the compression space during a separation of the piston compressor from the drive device, can be discharged. Thus, the pressure in the compression chamber during the first compression stroke of the reciprocating compressor after closing the clutch despite an increased pressure in the compression chamber by a compressed gas penetrated there does not rise above a set by the check valve maximum value. In a further embodiment, the inlet valve forms the venting device. The inlet valve is designed so that thus a connection between the inlet pipe and the

Compaction space is closed only from a pressure in the compression chamber, which is at least 0.1 bar, preferably at least 0.2 bar and in particular at least 0.5 bar higher than the pressure in the inlet line, which corresponds substantially to the ambient pressure. In this case, at a pressure in the compression chamber, which is below the limit of at least 0.1 bar, preferably at least 0.2 bar and in particular at least 0.5 bar overpressure, there is a continuing connection between the

Inlet pipe and the compression chamber. Thus, a compressed gas that enters the compression chamber during a separation of the piston compressor from the drive device, ie at standstill of the piston compressor, through this opening of the inlet valve in the inlet line can be discharged without a pressure build-up in the compression chamber of the compressor.

In one embodiment of the reciprocating compressor, in which the inlet valve is closed only from a predetermined pressure in the compression chamber, the inlet valve has a concave valve seat in particular on the valve plate and a substantially planar formed valve tongue, so that the valve tongue only after one by a pressure caused in the compression space elastic deformation sealingly against the valve seat. In such a

Embodiment closes the inlet valve only when a sufficiently high pressure acts in the compression space during the compression stroke, which deforms the valve tongue so that it bears sealingly against the concave valve seat. As long as the pressure in the compression chamber is lower than the pressure that causes the inlet valve to close, the inlet valve is open. Thus, by compressed gas, which passes during the separation of the reciprocating compressor from the drive means from the outlet line back into the compression space, no pressure build-up in the compression chamber can be effected.

In another embodiment of the reciprocating compressor, in which the inlet valve can be closed only from a predetermined pressure in the compression chamber, the inlet valve has a flat valve seat and a bent valve tongue. Consequently, the valve tongue is sealingly attached to the valve seat only after an elastic deformation caused by the pressure in the compression space. Also in this embodiment, the inlet valve closes only when during a compression stroke, a sufficiently high pressure acts in the compression space, which deforms the bent valve tongue designed such that it sealingly against the newly formed valve seat is applied. Again, the inlet valve remains open as long as the pressure in the compression chamber has a lower value than the pressure, which leads in particular during a compression stroke to close the inlet valve. Thus, even in this embodiment, a compressed gas that passes from the outlet line back into the compression chamber during the separation of the piston compressor from the drive means, leading to any pressure build-up in the compression chamber.

In another embodiment of the reciprocating compressor forms a venting channel

Venting device. By such a vent channel, which in particular produces a permanent connection to a region with a relation to the compression space lower pressure, in particular ambient pressure, gas from one end of the vent passage in

Compression space, which is under a higher pressure, are discharged through the vent channel in a region of lower pressure, in particular ambient pressure at the other end of the vent channel. As a result, a pressure equalization takes place with the compression chamber. If, therefore, during a separation of the piston compressor from the drive device gas from the pressurized outlet line passes back into the compression space, there can be no increased pressure build up because the gas is discharged through the vent channel.

In one embodiment, at least one end of the vent passage is disposed in the valve plate and in particular establishes a connection of the compression space to the surroundings of the reciprocating compressor or to its inlet system. A disadvantage of a permanently open venting channel is that it also allows for escape of the gas from the compression chamber during a compression stroke, whereby the efficiency of the compressor is reduced. In one embodiment, however, the vent channel has such a small cross-section that a pressure equalization through the vent channel is possible, the throttling action of the small cross-section of the vent passage but prevents the pressure flow of a larger volume flow during a compression stroke.

An alternative design which restricts escape of the gas from the compression space during a compression stroke has a suitable check valve in the vent passage, which closes it from a predetermined overpressure. A suitable check valve is for example a gravity ball valve. Advantageously, such a check valve is robust against a

Contamination caused by lubricating oil contamination. In another embodiment, at least one end of the ventilation channel is arranged in the cylinder wall, for example, a connection with the environment of the

Piston compressor produces. Starting from the outside of the cylinder wall, the

Venting channel having a connection device in the form of a line which serves as an extension of the vent passage and this connects in particular with the inlet system or with the interior of the crankcase of the reciprocating compressor. Such a venting channel also forms an opening in the compression chamber, through which gas can escape from the compression chamber even during the compression stroke, with the result that the efficiency of the piston compressor drops. Of the

Venting channel is therefore designed in particular large enough to equalize the pressure

ensure that gas volume flow, which can thereby be removed from the compression space by the drive device during a separation of the compressor, is at least as large as that in this period of time came from the outlet line back into the compression space

Gas volume flow of compressed gas from the outlet line. In one embodiment, the venting channel is arranged in the cylinder wall so that one end passes from the piston during the compression stroke from a certain piston position and thus is closed. This is the case in particular when the venting channel is arranged between an average stroke position of the piston and its top dead center. By virtue of this arrangement of the venting channel, gas which has returned from the outlet channel back into the compression chamber during a standstill of the piston compressor can be discharged in order to prevent pressure build-up in the compression chamber. At the same time, escape of gas from the compression space is prevented as soon as a piston ring has passed through the opening of the ventilation channel during the movement towards top dead center. In one embodiment of the reciprocating compressor, a check valve or a check valve is arranged in the venting channel or in a connecting device connected thereto. Such check valve or check valve on the one hand avoid escape of gas during a compression stroke of the piston compressor from the compression chamber, on the other hand, such

Check valve or check valve also serve to prevent suction of possibly contaminated gas in particular from the crankcase in the compression chamber. Although the piston, the cylinder, the cylinder head, etc. have been previously addressed in connection with the components of the reciprocating compressor, the characteristics described herein apply to a reciprocating compressor having two or more of these elements, since the present invention is not limited to single-stage reciprocating compressors but also for multi-stage reciprocating compressors can be used.

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 is a schematic representation of an exemplary reciprocating compressor of the state of

Technology;

FIG. 2 is an illustration of an exemplary exhaust valve as used in piston compressors in the prior art; FIG.

3 is a schematic representation of a first exemplary embodiment of a

piston compressor according to the invention, in which the venting device has a switchable valve device;

4 is a schematic representation of a second exemplary embodiment of a

Fig. 5 is a schematic representation of a third exemplary embodiment of a

piston compressor according to the invention, in which the venting device a

Having check valve;

Fig. 6 is a schematic representation of a fourth exemplary embodiment of a

piston compressor according to the invention, in which the venting a

Having venting channel;

Fig. 7 is a schematic representation of a fifth exemplary embodiment of a

piston compressor according to the invention, in which the venting a

Venting channel with check valve has; Fig. 8 is a schematic representation of a sixth exemplary embodiment of a piston compressor according to the invention, in which the venting a

Having venting channel;

9 is a schematic representation of a seventh exemplary embodiment of a

erfindungsge MAESSEN piston compressor, wherein the venting a

Having venting channel;

10 is a schematic representation of an eighth exemplary embodiment of a

piston compressor according to the invention in which the venting a

Having venting channel; and

11 is an illustration of a detail of a ninth exemplary embodiment of a

piston compressor according to the invention, in which the inlet valve, the

Venting forms.

Fig. 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 connected via a clutch 3 to a drive device (not shown, here an internal combustion engine) and selectively separable by means of the clutch 3 of this drive device. When the clutch 3 is opened, no torque is thus transmitted to the crankshaft 11 of the piston compressor 10, so that the

Crankshaft 11 is stopped during the separation of the reciprocating compressor 10 of the drive device.

The crankshaft 11 is connected to an eccentrically mounted thereon connecting rod 12, on which a piston 13 is mounted. The piston 13 is mounted axially movable in a cylinder 14 of the reciprocating compressor 10. The at least one crankshaft 11, a connecting rod 12 and a piston 13 having

Crank drive 15 is arranged in a crankcase 16, which is fixedly connected to the cylinder 14. By a rotational movement of the crankshaft 11, the piston 13 is moved by the connecting rod 12 in the cylinder 14 so that it performs a lifting movement.

Above the piston 13, the cylinder 14 is closed by a valve plate 20. Thus, the cylinder 14, the piston 13 and the valve plate 20 define the compression space 17 in the cylinder 14. On the valve plate 20, an inlet valve 21 is arranged, which is arranged between an inlet line 22 and the compression space 17. The inlet duct 22 is part of an inlet system 23, the fresh air from the environment through a filter (not shown) sucks and via the inlet line 22 through the cylinder head (not shown) to the compression space 17 supplies. The cylinder head is arranged above the valve plate 20 and has a cylinder head volume 24, which communicates via the inlet valve 21 with the compression chamber 17. The inlet valve 21 is designed as a check valve, which allows fresh air to be drawn into the compression space 17, but prevents backflow of the air sucked into the compression space 17 via the inlet line 22.

On the valve plate 20, an outlet valve 26 is further arranged, which is arranged between the compression chamber 17 and an outlet 27. About the outlet 27 compressed gas, here air, a compressed air storage, not shown here supplied. In this case prevents the exhaust valve 26, which is also designed as a check valve, a back flow of compressed air from the

Outlet 27 into the compression chamber 17th

FIG. 2 is an illustration of an exemplary exhaust valve 26 commonly used in piston compressors 10 in the prior art. The outlet valve 26 is attached to the valve plate 20 of the

Piston compressor 10 is disposed above the compression space 17. The valve plate 20 has an outlet opening 28 which connects the compression space 17 with a cylinder head volume 27 a arranged in valve plate 20 and cylinder head of the piston compressor 10, which forms part of the outlet line 27.

The outlet valve 26 has a valve body 26a on a valve tongue, which extends from a

predetermined pressure difference between the compression chamber 17 and the outlet 27 releases from the valve seat 26b and allows a flow of air from the compression chamber 17 into the outlet 27. The outlet valve 26 further has a contact element 26c arranged above the outlet opening 28, against which the valve tongue 26a bears in the opened state. As soon as the

Release valve tongue 26a from the valve seat 26b, the pressurized air from the compression chamber 17 can flow through the lateral open areas on the valve tongue 26a and the contact element 26c over into the outlet 27. Are impurities from the compression chamber 17 or from the cylinder head volume 27a, for example, from 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 solve, - In between the valve tongue 26 a and the valve seat 26 b, there is a risk that the exhaust valve 26 does not close completely. In this case, compressed air from the outlet conduit 27 in the

Compression chamber 17 flow back as soon as the pressure in the compression chamber 17 drops below the pressure in the outlet 27. 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 air flowing back therefrom with a pressure of up to 6 bar. When the reciprocating compressor 10 is then reconnected to the drive means, the reciprocating compressor 10 generates one at the first stroke

Internal pressure of about 60 bar. If the compression chamber 17 withstands this enormous internal pressure, the torque for the clutch 3 that arises on the crankshaft 11 is usually much too high, so that it slips, overheats and wears unacceptably quickly.

3 shows a schematic representation of a first exemplary embodiment of a piston compressor 10 according to the invention. The structure of the piston compressor 10 in FIG. 3 largely corresponds to the construction of the piston compressor 10 shown in FIG. 1 and described in that respect, so that identical elements of the piston compressors 10 are the same Reference signs are designated. In the following, only the differences between the reciprocating compressor 10 from FIG. 3 and the reciprocating compressor 10 from FIG. 1 will be explained.

The piston compressor 10 shown in FIG. 3 has a venting device in the form of a 2/2-way valve 31, which is arranged between the compression chamber 17 and the inlet system 23. The 2/2-way valve is a switchable valve device. In the exemplary embodiment in FIG. 3, the control line 31a of the 2/2-way valve 31 is connected to the control of the clutch 3

signal-connected. If the clutch 3 is opened and the piston compressor 10 is no longer driven therewith, the 2/2-way valve 31 is switched from the illustrated closed position to an open position in order to establish a connection between the compression chamber 17 and the inlet system 23 through which air can flow.

If compressed air enters the compression chamber 17 during standstill of the piston compressor 10, for example in the case of an outlet valve 26 which no longer closes tightly, pressure equalization with the inlet conduit 22 can take place through the open 2/2-way valve 31. Thus, no pressure build-up in the compression chamber 17, which in particular during the first compression stroke of the Piston compressor 10 at its restart could lead to damage to the reciprocating compressor 10 and / or the clutch 3.

FIG. 4 shows a schematic representation of a second exemplary embodiment of a piston compressor 10 according to the invention. The construction of the piston compressor 10 in FIG. 4 corresponds largely to the structure of the piston shown in FIG. 1 and described for this purpose

Piston compressor 10, so that the same elements of the reciprocating compressors 10 with the same

Reference signs are designated. The following are merely the differences of

Reciprocating compressor 10 of FIG. 4 compared to the reciprocating compressor 10 of FIG. 1 explained.

The piston compressor 10 shown in Fig. 4 has a venting device in the form of a pilot-operated check valve 32, which also serves as an inlet valve. Thus, the pilot-operated check valve 32 between the compression chamber 17 and the inlet system 23 is arranged. During the intake of fresh air from the inlet line 22 into the compression chamber 17, the pilot-operated check valve 32 opens automatically due to the applied pressure difference. The unlockable check valve 32 is also also a switchable valve device, which in addition to the automatic opening during the intake of fresh air and by means of a control signal in an open position is switchable. In the embodiment in Fig. 4 is the

Control line 32a of the pilot operated check valve 32 with a not shown

Control device signal connected. Depending on at least one predetermined parameter, such as the pressure in the compression chamber 17, the pilot-operated check valve 32 can be opened in order to establish a connection between the compression chamber 17 and the inlet line 22. If, during the standstill of the piston compressor 10, compressed air enters the compression chamber 17, for example in the case of an outlet valve 26 which no longer closes tightly, the pilot-operated check valve 32 can be opened in order to allow pressure equalization with the inlet line 22. Thus, no pressure build-up in the compression chamber 17 take place, which could lead to damage of the reciprocating compressor 10 and / or the clutch 3 in particular during the first compression stroke of the reciprocating compressor 10 when it is restarted. When restarting the reciprocating compressor 10, the pilot-operated check valve 32 is switched by the control device back to the working position in which it automatically opens when sucking fresh air from the inlet line 22 into the compression chamber 17 due to the pressure difference applied thereto.

5 shows a schematic representation of a third exemplary embodiment of a piston compressor 10 according to the invention. The construction of the piston compressor 10 in FIG. 5 corresponds largely to the construction of the one illustrated in FIG. 1 and described for this purpose

Reference signs are designated. The following are merely the differences of

Piston compressor 10 of FIG. 5 compared to the reciprocating compressor 10 of FIG. 1 explained.

The piston compressor 10 shown in FIG. 5 has a venting device in the form of a check valve 33, which is arranged between the compression chamber 17 and the inlet system 23. The check valve 33 arranged in addition to the inlet valve 21 between the compression chamber 17 and the inlet system 23 blocks in the opposite direction to the inlet valve 21, so that this is closed during the intake of fresh air into the compression chamber 17 and during compression during normal operation of the piston compressor 10. If, in the embodiment shown in FIG. 5, compressed air enters the compression chamber 17 during standstill of the piston compressor 10, for example in the case of an outlet valve 26 which no longer closes tightly, a pressure build-up in the compression chamber 17 first takes place here. The thereby adjusting pressure reaches no higher value than in a compression stroke, so that initially no venting of the compression chamber 17 is required. Only at the first compression stroke of the reciprocating compressor 10 after its recommissioning is due to the precompressed air in the compression chamber 17, a significantly increased pressure, which leads to damage of the

Piston compressor 10 and / or the clutch 3 can lead. The check valve 33 is therefore designed so that it opens a connection between the compression chamber 17 and the inlet line 21 with a sufficiently large cross section to remove air from the compression chamber 17 as soon as the pressure in the compression chamber 17 exceeds a critical value. In the exemplary

Piston compressor 10 for a commercial vehicle is the peak pressure in the compression chamber at

Normal operation between about 16 and 19 bar. An exemplary check valve 33 is therefore so executed that it opens, for example, at a pressure of 20 bar in the compression chamber 17 and thus discharges compressed air from the compression chamber 17.

FIG. 6 shows a schematic representation of a fourth exemplary embodiment of a piston compressor 10 according to the invention. The construction of the piston compressor 10 in FIG. 6 also largely corresponds to the structure of the piston shown in FIG

Kolbenkom ressors 10, so that the same elements of the reciprocating compressors 10 with the same

Reference signs are designated. The following are merely the differences of

Piston compressor 10 of FIG. 6 compared to the reciprocating compressor 10 of FIG. 1 explained.

The piston compressor 10 shown in FIG. 6 has a ventilation device in the form of a ventilation channel 34, which is arranged between the compression chamber 17 and the inlet system 23. The venting channel 34 establishes a connection between the compression chamber 17 and the inlet system 23, through which air can flow, so that during a standstill of the piston compressor, no pressure can build up in the compression chamber 17 which is substantially above the ambient pressure.

In the embodiment shown in FIG. 6, the venting channel 34 is arranged in the region of the valve plate 20 on the upper side of the cylinder 14 so that a continuous pressure equalization with the inlet line 32 of the reciprocating compressor 10 takes place through the venting channel 34. If, during a standstill of the reciprocating compressor 10 compressed air from the outlet 27 passes into the compression chamber 17, takes place through the vent passage 34, a pressure equalization with the inlet line 22 instead, whereby no pressure build-up in the compression chamber 17 can take place. A disadvantage of such a venting channel 34, however, that this is also during a compression stroke of the

Piston compressor 10 is open and escapes to be compressed air from the compression chamber 17 in this phase. This reduces the efficiency of the reciprocating compressor 10. The vent passage 34 is therefore designed so that it has only a small cross section in order to allow a sufficient pressure equalization during the stoppage of the reciprocating compressor 10 with the inlet system 23, but on the other hand has a throttling effect at high pressures, to limit the volume flow of the discharged air. 7 shows a schematic representation of a sixth exemplary embodiment of a piston compressor 10 according to the invention. The construction of the piston compressor 10 in FIG. 7 largely corresponds to the construction of the piston compressor 10 illustrated in FIG. 6 and described in that respect, so that identical elements of the piston compressors 10 are identical Reference signs are designated. In the following, only the differences between the reciprocating compressor 10 from FIG. 7 and the reciprocating compressor 10 from FIG. 6 are explained.

FIG. 7 shows a piston compressor 10, which also has a ventilation device in the form of a ventilation channel 39, which is arranged between the compression chamber 17 and the inlet system 23. In the vent passage 39, a check valve in the form of a gravity ball valve 40 is arranged, which closes the vent passage 39 when the pressure in the compression chamber 17 exceeds a predetermined value, which presses the ball of the gravity ball valve 40 against its gravity on a top of the gravity ball valve 40 arranged valve seat. The check valve thus restricts the escape of compressed air from the compression chamber 17 during a compression stroke.

8 shows a schematic representation of a sixth exemplary embodiment of a piston compressor 10 according to the invention. The construction of the piston compressor 10 in FIG. 8 largely corresponds to the construction of the piston compressor 10 shown in FIG. 6 and described in this regard, so that identical elements of the piston compressors 10 are identical Reference signs are designated. In the following, only the differences between the reciprocating compressor 10 from FIG. 8 and the reciprocating compressor 10 from FIG. 6 are explained.

The piston compressor 10 shown in FIG. 8 also has a ventilation device in the form of a ventilation channel 35, which is arranged between the compression chamber 17 and the inlet system 23. In contrast to the piston compressor 10 from FIG. 6, the ventilation channel 35 is arranged in the upper region of the wall of the cylinder 14. The venting channel 35 also establishes a connection between the compression chamber 17 and the cylinder head volume 24, through which air can flow, which allows pressure equalization between the compression chamber 17 and the inlet system 23.

As shown in Fig. 8, the vent passage 35 may be disposed approximately in the region which the upper piston ring sweeps about 60 ° before the top dead center of the piston 13. This will during the stoppage of the reciprocating compressor 10, a discharge of compressed air from the

Compressing space 17 is reached, which passes from the outlet 27 there, while the

Piston compressor 10 is disconnected from the drive device. At the same time, however, the air in the compression space 17 is prevented from escaping during the final phase of the compression stroke.

9 shows a schematic illustration of a seventh exemplary embodiment of a piston compressor 10 according to the invention. The construction of the piston compressor 10 in FIG. 9 largely corresponds to the structure of the piston compressor 10 illustrated in FIG. 8 and described in this regard, so that identical elements of the piston compressors 10 are identical Reference signs are designated. In the following, only the differences between the reciprocating compressor 10 from FIG. 9 and the reciprocating compressor 10 from FIG. 8 will be explained.

The piston compressor 10 shown in FIG. 9 has a venting device in the form of a venting channel 36, which is arranged between the compression chamber 17 and the interior of the crankcase 16. As in the case of the piston compressor 10 from FIG. 8, the ventilation channel 36 is arranged in the upper region of the wall of the cylinder 14. This one is air-permeable

Connection between the compression chamber 17 and the crankcase 16 ago. Since the crankcase 16 of the reciprocating compressor 10 allows pressure equalization with respect to the environment, there is substantially ambient pressure in its interior. This can be done via the vent passage 36, a pressure equalization between the compression chamber 17 and the crankcase 16.

FIG. 10 shows a schematic representation of an eighth exemplary embodiment of a piston compressor 10 according to the invention. The construction of the piston compressor 10 in FIG. 10 largely corresponds to the structure of the piston compressor 10 shown in FIG. 9 and described in that respect, so that identical elements of the piston compressors 10 are identical Reference signs are designated. In the following, only the differences between the reciprocating compressor 10 from FIG. 10 and the reciprocating compressor 10 from FIG. 9 will be explained.

The piston compressor 10 shown in Fig. 10 has a venting device in the form of a vent passage 37 which, corresponding to the vent passage 36 of FIG. 9 between the

Compression chamber 17 and the interior of the crankcase 16 is arranged. Compared to the

Venting channel 36 of FIG. 9, a check valve 38 is disposed in the vent passage 37, which prevents backflow of air from the crankcase 16 in the compression chamber 17. The check valve 38 may be designed so that it opens at a low pressure difference between the pressure in the compression chamber 17 and the pressure in the crankcase 16 to prevent pressure build-up in the compression chamber 17 during a service life of the reciprocating compressor 10.

11 is an illustration of a detail of a ninth exemplary embodiment of a reciprocating compressor 10 according to the present invention, in which the intake valve 21 constitutes the venting means. The elements of the inlet valve 21 are shown in exploded view in FIG. 11. The

Intake valve 21 forms the upper end of the compression space 17 in the cylinder 14. The valve tongue 21a is formed integrally with a first element of the intake valve 21, which is disposed between the cylinder 14 and a abutment member 21b of the intake valve 21. The exemplified investment element 21b has two valve openings 21c, which depends on the

Pressure difference between the compression chamber 17 in the cylinder 14 and the pressure in the inlet system 23 are closed by the valve tongue 21 a.

The valve tongue 21a has a curvature which is designed such that the valve tongue 21a rests against the contact element 21b from a pressure in the compression space 22 (dashed representation of the valve tongue 21a) which in the exemplary embodiment is 0.4 bar higher than the pressure in the inlet system 23 (FIG. Ambient pressure) while closing the valve openings 21c. At a pressure difference of less than 0.4 bar, the valve tongue 21a always has a curvature that a connection between the inlet system 23 and the compression chamber 17 is made. Thus, a compressed gas that has entered the compression space 17 through the valve openings 21 c of the intake valve 21 in the

Inlet pipe 22 can be discharged without a pressure build-up in the compression chamber 17 of the compressor 10 takes place.

In another, not shown but acting in the same way embodiment of the

Piston compressor 10, the inlet valve 21 may also have a contact element 21b, which has a recess in the region of the valve openings 21c, so that the valve tongue 21a also in this

Execution only from a predetermined pressure in the compression chamber 17 sealingly applied to the contact element 21b. BEZUGSZEICHEIMUSTE

3 clutch

10 piston compressor

11 crankshaft

12 connecting rods

13 pistons

14 cylinders

15 crank drive

16 crankcase

17 compaction space

20 valve plate

21 inlet valve

21a valve tongue

21b contact element

21c valve opening

22 inlet pipe

23 inlet system

24 cylinder head volume (inlet)

26 exhaust valve

26a valve tongue

26b valve seat

26c contact element

27 outlet pipe

27a Cylinder head volume (outlet)

28 outlet opening

31 2/2-way valve

31a control line

32 check valve

32a control line

33 check valve

34 venting channel Venting channel Venting channel Venting channel Check valve Check valve Gravity ball '

Claims

claims

A reciprocating compressor for compressing a gas, which is optionally separable from a drive device by means of a clutch (3), comprising an inlet valve (21) which is arranged between an inlet line (22) for gas to be compressed and a compression space (17) of the reciprocating compressor (10 ) and an outlet valve (26) which is arranged between the compression chamber (17) of the piston compressor (10) and a compressed gas outlet line (27), characterized in that the piston compressor (10) has a venting device (31, 32, 33, 34, 35, 36, 37, 39) through which compressed gas, during the separation of the reciprocating compressor (10) of the

Drive device from the outlet line (27) back into the compression space (17) passes, from the compression space (17) can be discharged.

2. Reciprocating compressor according to claim 1, characterized in that the compressed gas from the compression chamber (17) can be discharged into an area with ambient pressure of the environment itself, a gas inlet connected to the inlet system (23) gas space (22, 24) or the Inside the crankcase (16) is formed.

3. Piston compressor according to one of the preceding claims, characterized in that a switchable valve means (31, 32) forms the venting device.

4. Piston compressor according to one of claims 1 or 2, characterized in that a check valve (33) forms the venting device.

5. Piston compressor according to one of claims 1 or 2, characterized in that the inlet valve (21) forms the venting device, wherein the inlet valve (21) is formed so that a connection between the inlet line (22) and the compression space (17) only from a predetermined pressure in the compression chamber (17) is closable, wherein the predetermined pressure is at least 0.1 bar, preferably at least 0.2 bar and in particular at least 0.5 bar higher than the pressure in the inlet line (22).

6. Piston compressor according to claim 5, characterized in that the inlet valve (21) has a concave valve seat and a substantially planar formed valve tongue, so that the valve tongue sealingly bears against the valve seat only after an elastic deformation caused by the pressure in the compression space (17).

7. piston compressor according to claim 5, characterized in that the inlet valve (21) has a flat valve seat formed and a bent valve tongue, so that the

Valve tongue sealingly engages the valve seat after a by the pressure in the compression chamber (17) caused elastic deformation.

8. Piston compressor according to one of claims 1 or 2, characterized in that a venting channel (34, 35, 36, 39) forms the venting device.

9. Piston compressor according to claim 8, characterized in that at least one end of the venting channel (34, 35, 36, 39) in the valve plate (20) or in the cylinder wall (14) is arranged.

10. Piston compressor according to one of claims 8 or 9, characterized in that in the vent channel (34, 35, 36, 39) a check valve (38) or a check valve (40) is arranged.