EP4150211A1

EP4150211A1 - Reciprocating compressor for generating oil-free compressed air

Info

Publication number: EP4150211A1
Application number: EP21725046.3A
Authority: EP
Inventors: Christian Busch
Original assignee: OET GmbH
Current assignee: OET GmbH
Priority date: 2020-05-11
Filing date: 2021-05-03
Publication date: 2023-03-22
Also published as: DE102020112664A1; WO2021228598A1

Abstract

The invention relates to a reciprocating compressor for generating oil-free compressed air, comprising at least one guide piston (22) and a pressure-generating piston (32). The guide piston (22) is coupled to a swashplate (14), and the pressure-generating piston (32) is guided in a pressure-generating cylinder (31) without oil. The invention is characterized in that the guide piston (22) is guided in a guide cylinder (21) and is connected to the pressure-generating piston (32) via a coupling rod (24), the coupling rod (24) is guided through at least one sealing element (43) which seals the engine compartment (11) and the compression chamber (33) from each other, the guide piston (22) acts as a crosshead guide for the coupling rod (24), and an electric drive (12) is arranged in the engine compartment (11). The invention additionally relates to a compressed air system of a truck, said compressed air system comprising such a reciprocating compressor, and to the use of such a reciprocating compressor in a compressed air system of a truck.

Description

Reciprocating compressor for generating oil-free compressed air

DESCRIPTION

The invention relates to a reciprocating compressor for generating oil-free compressed air according to the preamble of claim 1. Furthermore, the invention relates to a compressed air system of a truck with such a reciprocating compressor and the use of a reciprocating compressor as a compressed air generator in a compressed air system of a truck.

Reciprocating compressors for generating oil-free compressed air are already known from the prior art. For example, EP 0 994 252 B1 and EP 0 859 151 B1 describe reciprocating compressors which comprise a swash plate which is arranged on a shaft and acts on several guide pistons. The guide pistons are directly connected to pressure generating pistons which are guided within a pressure generating cylinder. In order to avoid compressed air from the pressure generating cylinder from reaching an engine room in which the swash plate is arranged, the guide piston is guided by sealing elements.

However, the direct connection between the guide piston and the pressure generating piston has disadvantages. In particular, tilting moments can be exerted on the guide piston by the swash plate, which can lead to greater wear of the sealing elements when the guide piston is moved rapidly and repeatedly by the sealing elements and the resulting slight tilting of the guide piston. Thus, in known reciprocating compressors, the tightness of the pressure generating cylinders cannot be guaranteed over a long period of time.

Another disadvantage of the known reciprocating compressors is that they require a drive which is arranged outside the housing of the reciprocating compressor. This has disadvantages in motor vehicles in which less and less installation space is available, for example due to the large number of exhaust gas cleaning units that have now been required. A reciprocating compressor for generating compressed air is also known from US Pat. No. 3,749,523 A. In this reciprocating compressor, the swash plate is connected to several pressure pistons on both sides. This has the disadvantage that, on the one hand, compressed air can escape past the pressure piston into the area of the swash plate. On the other hand, the known reciprocating compressor requires a large amount of space due to the double number of pressure generating cylinders, which are also opposite one another.

The object of the invention is to provide a reciprocating piston compressor for generating oil-free compressed air, which is compact and ensures a high level of tightness over a long service life. Another object of the invention is to specify a compressed air system of a truck with such a reciprocating compressor and the use of such a reciprocating compressor as a compressed air generator in a compressed air system of a truck.

This object is achieved with regard to the reciprocating compressor by the subject matter of claim 1, with regard to the compressed air system by the subject matter of claim 15 and with regard to the use of a reciprocating compressor by the subject matter of claim 16.

The invention is based on the idea of specifying a reciprocating compressor for generating oil-free compressed air with at least one guide piston and a pressure generating piston, the guide piston being coupled to a swash plate and the pressure generating piston guided oil-free in a pressure generating cylinder. According to the invention, the guide piston is guided in a guide cylinder and connected to the pressure generating piston via a coupling rod. The coupling rod is guided through at least one sealing element which seals off an engine compartment and a compression compartment from one another. The guide piston also acts as a crosshead guide for the piston rod. An electric drive is also arranged in the machine room.

In contrast to the prior art, in the reciprocating piston compressor according to the invention, the pressure generating piston and the guide piston are through a coupling rod connected, the guide piston being guided in a guide cylinder and forming a cross-head guide for the piston rod. This ensures stable guidance of the piston rod, which is guided through the sealing element. Misalignments or any tilting elements that occur do not affect the seal. This reduces the wear on the sealing element and ensures a long service life for the floating piston compressor. In addition, high forces can be transmitted in this way, so that compressed air can be generated permanently at a high pressure.

Another advantage of the invention is achieved by integrating an electric drive into the machine room. In this way, the floating piston compressor according to the invention forms a compact, integrated unit which contains all the components for generating compressed air. This not only reduces the cost of installing a compressed air generator in a vehicle, in particular a truck, but also enables existing vehicles to be easily retrofitted. In addition, such an electrically driven reciprocating compressor, which has a compact design, can also be used well in vehicle trailers. With increasing electrification of the drive train, including in trucks, it is also beneficial if the compressed air generator is operated electrically. To this extent, the reciprocating piston compressor according to the invention offers the prerequisites for use in trucks that are driven electrically or partially electrically, in particular hybrid-electrically.

In a preferred embodiment of the invention, the engine room in which the electric drive is arranged can be enclosed by an engine housing. In this way, the entire engine compartment is hermetically sealed, so that oil can circulate therein to lubricate the moving parts, in particular the guide piston. The engine housing also promotes the simple installation of the reciprocating compressor in a vehicle and also serves as noise insulation.

In a further preferred variant of the reciprocating piston compressor according to the invention, it is provided that the pressure generating cylinder has an inlet valve and an outlet valve on both sides, so that the pressure generating piston is effective in generating pressure on both sides. Through the Pressure generation on both sides increases the efficiency of the reciprocating compressor considerably. In particular, the output of compressed air can thus be generated with a higher degree of continuity, since a compression occurs with each movement of the pressure generating piston, regardless of its direction of movement.

The pressure generating cylinder can be arranged in a cylinder block which is covered on a side facing the engine compartment by a first valve plate and on a side facing away from the engine compartment by a second valve plate. Overall, two valve plates can therefore be provided which cover the cylinder block on both sides. This design has considerable advantages in production, since no individual valves have to be integrated into the cylinder block. Rather, whole valve plates are used which contain all valves for all pressure-generating cylinders arranged in the cylinder block. This ensures a simple and very maintenance-friendly construction of the reciprocating piston compressor.

The pressure generating piston in the pressure generating cylinder preferably delimits two compression spaces, the first valve plate forming a first inlet valve and a first outlet valve which are assigned to a first compression space. The second valve plate can form a second inlet valve and a second outlet valve which are assigned to the second compression chamber. In this respect, each valve plate preferably has an inlet valve and an outlet valve, so that it is ensured that the pressure-generating piston is effective in generating pressure on both sides. It is therefore a doubly effective pressure generating piston. The size of the compression spaces described here can be changed, namely by the movement of the pressure generating piston.

The guide cylinder is arranged in a guide block which is connected to the engine room, in particular the engine housing. The provision of a separate guide block also serves to simplify the construction of the reciprocating compressor and also enables the reciprocating compressor to be manufactured easily. The connection of the guide block to the engine room ensures that oil circulating in the engine room also circulates in the guide block, in particular in the guide cylinder, so that lubrication takes place between the guide piston and the guide cylinder. In this respect, it is preferably provided that the sealing element is arranged between the guide block and the cylinder block, so that no oil penetrates into the cylinder block, in particular into the pressure generating cylinder.

Essentially, the floating piston compressor can be divided into an oil-free side and an oil-carrying side. In any case, the oil-free side includes the pressure generating cylinder. The oil-conducting side comprises at least the engine room and the guide cylinder.

In a preferred embodiment of the floating piston compressor according to the invention, the first valve plate is covered with a first cylinder head and the second valve plate is covered with a second cylinder head, the first cylinder head having at least one first gas collecting chamber and the second cylinder head having at least one second gas collecting chamber. The gas collecting spaces are preferably designed in such a way that they act as air vessels and thus dampen the pulsations that occur as a result of the generation of the compressed air by means of the moving pressure generating pistons. The compressed air generated is therefore collected in the gas collection rooms and is almost continuously released to the other compressed air system.

The cylinder block can also have a connecting space which connects the first gas collecting space of the first cylinder block with the second gas collecting space of the second cylinder block. In this way, the compressed air components generated by the double-acting pressure generating piston are first brought together before they are released from the floating piston compressor into a compressed air system. The connecting space can also provide an air chamber function in order to smooth out the fluctuations in compressed air caused by the pulsed compressed air and thus further contribute to the fact that a substantially continuous flow of compressed air is delivered into the compressed air system.

The second cylinder head preferably has an outlet opening for compressed air and / or an inlet opening for ambient air. Air at low pressure (low pressure air) is supplied to the floating piston compressor via the inlet opening for ambient air Exit opening is released. The inlet opening is not necessarily open to the environment, but can also be connected to a compressed air system if the reciprocating piston compressor is integrated in a closed compressed air circuit.

The first cylinder head can have a first gas intake chamber and the second cylinder head can have a second gas intake chamber, the cylinder block having at least one air supply channel which connects the second gas intake chamber to the first gas intake chamber. The inlet opening for low-pressure air preferably opens into the second gas suction chamber. The second gas suction chamber thus collects low-pressure air, so that sufficient low-pressure air is available for suction via the pressure generating piston. Since the pressure generating piston is preferably doubly effective, the air supply channel is provided which connects the second gas suction space to the first gas suction space, the first gas suction space also collecting low-pressure air in order to make it available for generating compressed air by means of the pressure generating piston. The air supply channel in the cylinder block can be designed as an annular channel.

In a preferred variant of the reciprocating piston compressor according to the invention, it is provided that the engine compartment, in particular at least the engine housing, is liquid-cooled, in particular water-cooled. Specifically, the engine housing can have at least one cooling channel. Furthermore, at least one cooling channel can be provided in the guide block and / or in at least one cylinder head. The cooling channels preferably carry a cooling liquid. The cooling liquid can be water. In this way, good and effective cooling of the reciprocating compressor can be achieved. In addition, the integration of cooling channels in the engine housing and / or the guide block and / or one of the cylinder heads ensures the compact design of the reciprocating compressor.

Furthermore, a cooling sleeve with cooling channels can be provided which encases the engine housing, the guide block, the cylinder block, the first valve plate, the second valve plate, the first cylinder head and / or the second cylinder head. In particular, the cooling sleeve can encase the entire outer circumferential surface of the reciprocating compressor. With this variant cooling ducts in the engine housing can be dispensed with, although these can also be provided.

In a further preferred variant of the reciprocating piston compressor according to the invention, a sound- and / or vibration-absorbing protective cover is provided, which extends around the cooling cover. Such a sound and / or vibration insulation is particularly interesting for the integration of the reciprocating compressor in electrically driven vehicles, since the smallest vibrations appear noticeable here.

It is particularly preferred if, in a variant of the reciprocating piston compressor according to the invention, the first compression chamber and the second compression chamber of the same pressure generating cylinder and / or several first compression chambers and / or second compression chambers of different pressure generating cylinders are fluidly connected to one another in such a way that a two-stage compression is effected. In general, it can be provided that the reciprocating piston compressor has a plurality of pressure generating cylinders which each form a first compression chamber and a second compression chamber.

For example, all of the first compression spaces can precompress the low-pressure air drawn in via the first gas intake duct, so that medium-pressure air (medium-pressure air) is collected in the first gas collection space. The medium-pressure air can then be passed from the first gas collecting space to the second gas suction space. The medium-pressure air then passes from the second gas collecting chamber into the second compression chamber, where it is further compressed to form high-pressure air. The high pressure air reaches the second gas collecting chamber and from there to the outlet opening.

A secondary aspect of the invention relates to a compressed air system of a truck, in particular a hybrid or fully electric truck, with a reciprocating compressor described above. As already explained, the use of the reciprocating piston compressor according to the invention in a compressed air system of an at least partially electrically operated truck is particularly advantageous, since the reciprocating compressor with its electric drive can be integrated into such a truck with little effort. In this respect, according to a further preferred aspect of the invention, a use of a previously described reciprocating piston compressor as a compressed air generator in the compressed air system of a truck, in particular a hybrid or fully electric truck, is disclosed and claimed. The compressed air system can in particular be a compressed air brake system of a truck.

The invention is explained in more detail below using an exemplary embodiment with reference to the accompanying schematic drawings. Show in it:

Fig. 1: an exploded view of an inventive

Reciprocating compressor according to a preferred embodiment;

Fig. 2: a longitudinal section through the reciprocating compressor according to

Fig. 1;

FIG. 3: the detail X of the reciprocating piston compressor according to FIG. 2;

Fig. 4: an exploded view of the first valve plate of the

Reciprocating compressor according to FIG. 1; and

Fig. 5: an exploded view of the second valve plate of the

Reciprocating compressor according to FIG. 1.

1 shows an exploded view of the reciprocating compressor with an engine housing 10, a guide block 20, a first cylinder head 40, a cylinder block 30 and a second cylinder head 50. A first valve plate 60 is arranged between the first cylinder head 40 and the cylinder block 30. A second valve plate 70 is arranged between the cylinder block 30 and the second cylinder head 50. The reciprocating compressor also has an electronics housing 80 which is attached to the engine housing 10. The electronics housing 80 encloses an electronics space 81 which accommodates electronic components, for example an inverter, for the electric drive 12 of the reciprocating compressor. The engine housing 10 encloses an engine compartment which accommodates the electric drive 12, a drive shaft 13 and a swash plate 14. The drive shaft 13 is supported by shaft bearings 15 in the engine room. Guide cylinders 21, in which guide pistons 22 are guided, are arranged in the guide block 20. The guide pistons 22 are also coupled in an articulated manner to the swash plate 14.

In the cylinder block 30, pressure generating cylinders 31 are also provided, in which pressure generating pistons 32 are guided. The pressure generating pistons 32 are each connected to one of the guide pistons 22 by a coupling rod 24. The cylinder block 30 is closed on both sides by valve plates 60, 70. The valve plates 60, 70 comprise a structure of three letters each, which fulfill different functions.

The first valve plate 60 has a first outlet valve disk 61 and a first inlet valve disk 62, which are arranged on opposite sides of a first folded disk 63. The second valve plate 70 comprises a second outlet valve disk 71 and a second inlet valve disk 72, which are arranged on opposite sides of a second folded disk 73.

The second cylinder head 50 has a lateral inlet opening 53. The lateral inlet opening 53 opens into a second gas suction space 51. The second gas suction space 51 is annular and runs around a second gas collecting space 52 which is formed centrally in the second cylinder head 50. The second cylinder head 50 also has an annular air supply duct 36 which extends around the outside of the second gas intake chamber 51.

The construction of the floating piston compressor according to the embodiment described here can be seen clearly in FIG. In particular, it can be seen that the floating piston compressor has a modular design, the individual modules being formed by the engine housing 10, the guide block 20, the first cylinder head 40, the cylinder block 30, the second cylinder head 50 and the electronics housing 80.

The engine housing 10 encloses or delimits an engine compartment 11 in which the electric drive 12, the drive shaft 13 and the wobble screw 14 are arranged. The engine housing 10 is connected directly to the guide block 20, in which guide cylinders 21 and guide pistons 22 guided therein are arranged. The guide pistons 22 extend into the engine compartment 11 and are connected in an articulated manner to the swash plate 14.

The first cylinder head 40 directly adjoins the guide block 20. The first cylinder head 40 has bushings for one coupling rod 24 each, which extends from the guide piston 22 to the pressure generating piston 32 and connects them. A sealing element 43 through which the coupling rod 24 is guided is also arranged in the first cylinder head 40. The sealing element 43 seals the coupling rod 24. In particular, the sealing element 43 ensures an oil-tight and airtight separation between an oil-carrying side of the floating piston compressor and an oil-free side of the floating piston compressor. The oil-carrying side of the floating piston compressor comprises the engine housing 10 and the guide block 20. The first cylinder head 40, the cylinder block 30 and the second cylinder head 50 belong to the oil-free side of the floating piston compressor.

In the first cylinder head 40, a first gas suction space 41 and a first gas collecting space 42 are also formed. The first gas suction space 41 is preferably designed as an annular space and grants access to all pressure generating cylinders 31. Likewise, the first gas collecting space 42 is preferably fluidly connected to all pressure generating cylinders 31.

The cylinder block 30 comprises the pressure generating cylinders 31, in which the pressure generating pistons 32 are guided. Furthermore, a central connecting space 35 is provided in the cylinder block 30, which connects the first gas collecting space 42 of the first cylinder head 40 to the second gas collecting space 52 of the second cylinder head 50. An air supply duct 36 is also formed around the pressure generating cylinder 31 in the cylinder block 30. The air supply channel 36 is preferably designed as a circumferential channel around the circumference of the cylinder block 30. The air supply channel 36 essentially forms an annular channel, this not being completely circular, but rather having corresponding formations for assembly bores, as can be seen in FIG. 1. The air supply channel 36 connects the second gas intake chamber 51 of the second cylinder head 50 to the first gas intake chamber 41 of the first cylinder head 40. The second cylinder head 50 has the second gas intake chamber 51, which is connected to the outside via the inlet opening 53. The inlet opening 53 can be open to the environment or connected to a return of a compressed air system. Furthermore, the second gas collecting chamber 52, which is fluidly connected to an outlet opening 54, is arranged in the second cylinder head 50.

The pressure generating cylinders 31 in the cylinder block 30 each have two variable compression spaces 33, 34. In the operating state of the reciprocating piston compressor, as shown in FIG. 2, the pressure generating piston 32 in the upper pressure generating cylinder 31 is at its top dead center, so that the second compression chamber 34 can no longer be seen. The first compression space 33, however, has its maximum volume. The opposite applies to the pressure generating cylinder 31 shown below in FIG. 2. The first compression chamber 33 cannot be seen because the pressure generating piston 32 has reached bottom dead center. The second compression space 34, however, has its maximum volume.

The first valve plate 60 is arranged between the first cylinder head 40 and the cylinder block 30. The first valve plate 60 comprises a first inlet valve 64, which connects the first gas suction chamber 41 to the first compression chamber 33. Furthermore, a first outlet valve 65, which connects the first compression chamber 33 to the first gas collecting chamber 42, is formed in the first valve plate 60.

The second valve plate 70 is constructed essentially analogously. It has a second inlet valve 74 which connects the second gas collection chamber 51 to the second compression chamber 34. Furthermore, the second valve plate 70 comprises a second outlet valve 75, which connects the second compression chamber 34 to the second gas collection chamber 52.

The cooling channels 16, which are used for cooling the reciprocating piston compressor, can also be clearly seen in FIG. 2. The cooling channels 16 preferably extend annularly over the circumference of the reciprocating compressor. In particular, a cooling duct 16 is formed in the area of the engine housing 10, in particular in the area of the electric drive 12. Another cooling channel 16 is formed in the guide block 20, this cooling channel 16 also extending into the first cylinder head 40.

3 shows a detail of the floating piston compressor in the area of the guide block 20 of the first cylinder head 40 and the cylinder block 30. The connection of the coupling rod 24 to the guide piston 22 can be seen particularly well. The guide piston 22 comprises a threaded bore into which a threaded extension 25 of the Coupling rod 24 engages. The threaded connection is considerably shorter than the guide piston 22, as a result of which misalignments, which may arise when the floating piston compressor is in the lowering position, are automatically compensated for. Furthermore, the coupling rod 24 has an annular notch 26 in the vicinity of the guide piston 22. The annular notch 26 is positioned so that it does not reach the sealing element 43, which is arranged in the first cylinder head 40, during operation. The annular notch 26 also helps to compensate for any misalignment that may occur.

The guide piston 22 slides against the inner wall of the guide cylinder 21. A sealing ring 23, which is arranged in an annular groove of the guide piston 22, is provided for sealing. The sliding connection between the guide piston 22 and the guide cylinder 21, which exists over a considerable length, ensures cross-head guidance for the coupling rod 24. Even in the event of unbalances in the swash plate, it is ensured that hardly any tilting moments act on the coupling rod 24, so that it is well and continuously linear is led. This in turn ensures that the wear of the sealing element 43 is low and that the engine compartment 11 is sealed off from the first compression compartment 33 or between the oil-carrying side and the oil-free side of the reciprocating piston compressor.

In Fig. 4, the first valve plate 60 is shown again in detail. It can be seen that the first valve plate 60 has a first outlet valve disc 61, a first inlet valve disc 62 and a folded disc 63 arranged in between. The folded disk 63 comprises several bores, in particular an inlet bore 29, two outlet bores 28 and a passage 27 for each pressure generating cylinder 31. The passage 27 serves to guide the coupling rod 24 through the first valve plate 60. On the The first inlet valve 64 rests on the inlet bore 29. The first inlet valve 64, like preferably all valves of the two valve plates 60, 70, is designed as a flutter valve. The outlet bores 28 in the first valve plate 60 are each covered by a first outlet valve 65. The first valve plate 60 thus has two first outlet valves 65 for each pressure generating cylinder 31.

An opening is provided in the center of the first valve plate 60 which ensures that the first gas collecting space 42 has access to the connecting space 35.

The second valve plate 70 shown in FIG. 5 has a similar structure. The second valve plate 70 comprises a second outlet valve disk 71, a second inlet valve disk 72 and a second folded disk 73 arranged in between. The second outlet valve disk 71 comprises several second outlet valves 75. In contrast to the first outlet valve disk 61, which provides two first outlet valves 65 for each pressure generating cylinder 31 , the second outlet valve disk 71 has a single second outlet valve 75 for each pressure generating cylinder 31.

The second inlet valve disk 72 comprises a plurality of second inlet valves 74. The folded disk 73 has a plurality of inlet bores 29, which are covered by the second inlet valves 74, essentially analogously to the first folded disk 63. Furthermore, several outlet bores 28, which are covered by the second outlet valves 75, are provided in the second folded disk 73. In contrast to the first folded disk 63, in the second folded disk 73 only one outlet bore 28 is provided for each pressure generating cylinder 31. A passage 27 as in the first folded disk 63 is not required in the second folded disk 73, since the coupling rod 24 ends in front of the second valve plate 70.

The mode of operation of the floating piston compressor is explained particularly clearly with the aid of FIG. 2. The floating piston compressor compresses compressed air that only circulates in the oil-free section of the floating piston compressor.

The compressed air first reaches the second gas suction chamber 51 as low pressure air via the inlet opening 53. The second gas suction chamber 51 collects the Low-pressure air and passes it on to the first gas suction chamber 41 via the air supply duct 36. In the first gas intake chamber 41, in the second gas intake chamber 51 and in the air supply channel 36 there is thus low-pressure air. If the pressure generating piston 32 in the pressure generating cylinder 31 is now guided from one dead point to the next, then on the one hand low-pressure air is sucked in from one of the gas suction spaces 41, 51. In the illustration according to FIG. 2, for example, the upper pressure generating piston has reached its top dead center, so that the first compression chamber 33 is filled with low-pressure air. During the intake process, the corresponding inlet valve 64 opens,

65 and thus allows low-pressure air to flow into the respective compression chamber 33, 34 from the respectively assigned gas suction chamber 41, 51.

When the pressure generating piston 32 moves, low-pressure air is sucked in from the respectively assigned gas suction chamber 41, 51. At the same time, the pressure generating piston 32 displaces low-pressure air previously sucked in the opposite compression chamber 34, thereby generating high-pressure air. In the illustration according to FIG. 2, it can be seen, for example, that the second compression chamber 34 initially contains low-pressure air. As soon as the pressure generating piston 32 is moved from bottom dead center to top dead center, that is to say in the direction of the second cylinder head 50, the compression space 34 is reduced, whereby the low-pressure air contained therein is compressed. This compression creates high-pressure air which reaches the second gas collecting chamber 52 via the second outlet valve 75.

High pressure air, which with a counter-rotating movement of the

Pressure generating piston 32, i.e. in the direction of the first cylinder head 40, is generated via the first outlet valve 65 into the first gas collecting chamber 42. Via the connecting chamber 35, the high-pressure air from the first gas collecting chamber 42 reaches the second gas collecting chamber 52 Collected high pressure air then exits the reciprocating compressor via the outlet port 54.

The reciprocating compressor shown in FIG. 2 is designed essentially as a single-stage reciprocating compressor. This means that the low-pressure air entering via the inlet opening 53 is compressed only once and as High pressure air 52 is output. However, it is also possible to design the reciprocating compressor as a two-stage or multi-stage reciprocating compressor. For example, a total of six pressure generating cylinders 31 can be provided, three pressure generating cylinders 31 performing a pre-compression to a medium air pressure, the other three pressure generating cylinders 31 being supplied with this medium pressure air via the inlet valves 64, 74. The other pressure generating cylinders 31 then compress this medium-pressure air further to form high-pressure air.

Alternatively, it is also possible for each individual pressure-generating cylinder 31 to carry out a pre-compression on the one hand and a post-compression on the other hand. For example, all first compression spaces 33 can compress a low-pressure air to form medium-pressure air and all second compression spaces 34 can then recompress the medium-pressure air to form high-pressure air. The reciprocating piston compressor is preferably designed so that high pressure air can be generated with a pressure of at least 10 bar.

As can also be seen from FIG. 2, the first gas collecting space 42, the connecting space 35 and the second gas collecting space 52 each have comparatively large volumes, whereas the diameter of the outlet opening 54 is smaller, in particular compared to the second gas collecting space 52. As a result, an air chamber effect is achieved in the gas collecting spaces 42, 52 and the connecting space 53. This means that the compressed air ejected in a pulsating manner from the pressure generating cylinders 31 is smoothed with regard to its pressure fluctuations. The wind kettle effect thus ensures that high-pressure air is emitted relatively continuously via the outlet opening 52.

List of reference symbols

10 engine casing

11 machine room

12 electric drive

13 drive shaft

14 swashplate

15 shaft bearings

16 cooling duct

20 guide block

21 guide cylinder

22 guide piston

23 O-ring

24 coupling rod

25 thread extension

26 notch

27 Implementation

28 outlet hole

29 Inlet Hole

30 cylinder block

31 pressure generating cylinder

32 pressure generating pistons

33 first compression area

34 second compression area

35 connecting room

36 air supply duct

40 first cylinder head

41 first gas intake space

42 first gas collection room

43 sealing element 50 second cylinder head

51 second gas intake chamber

52 second gas collection room

53 inlet opening 54 outlet opening

60 first valve plate

61 first exhaust valve disc

62 first inlet valve disc

63 first retaining disk 64 first inlet valve

65 first exhaust valve

70 second valve plate

71 second exhaust valve disc

72 second inlet valve disk 73 second retaining disk

74 second inlet valve

75 second exhaust valve

80 electronics housings

81 electronics room

Claims

EXPECTATIONS

1. Reciprocating compressor for generating oil-free compressed air with at least one guide piston (22) and a pressure generating piston (32), wherein the guide piston (22) is coupled to a swash plate (14) and the pressure generating piston (32) is guided oil-free in a pressure generating cylinder (31) , because the guide piston (22) is guided in a guide cylinder (21) and is connected to the pressure generating piston (32) via a coupling rod (24), the coupling rod (24) being connected by at least one sealing element (43) is guided, which seals an engine room (11) and a compression chamber (33) from one another and the guide piston (22) acts as a cross-head guide for the coupling rod (24), and an electric drive (12) is arranged in the engine room (11).

2. Reciprocating compressor according to claim 1, dad u rch geken nzeich net that the engine room (11) is enclosed by an engine housing (12).

3. Reciprocating compressor according to one of the preceding claims, dad u rch geken nzeich net that the pressure generating cylinder (31) has an inlet valve (64, 74) and an outlet valve (65, 75) on both sides, so that the pressure generating piston (32) generates pressure on both sides is effective.

4. Reciprocating compressor according to one of the preceding claims, dad u rch geken nzeich net that the pressure generating cylinder (31) is arranged in a cylinder block (30) which is on a side facing the engine room (11) through a first valve plate (60) and on a side facing away from the engine compartment (11) is covered by a second valve plate (70).

5. Reciprocating compressor according to claims 3 and 4, dad u rch geken nzeich net that the pressure generating piston (32) in the pressure generating cylinder (31) delimits two compression spaces (33, 34), the first valve plate (60) having a first inlet valve (64 ) and forms a first outlet valve (65), which are assigned to a first compression chamber (33), and wherein the second valve plate (70) forms a second inlet valve (74) and a second outlet valve (75) which are connected to the second compression chamber (34) assigned.

6. Reciprocating compressor according to one of the preceding claims, dad u rch geken nzeich net that the guide cylinder (21) is arranged in a guide block (20) which is connected to the engine room (11), in particular the engine housing (10).

7. Reciprocating compressor according to one of claims 4 to 6, dad u rch geken nzeich net that the first valve plate (60) with a first cylinder head (40) and the second valve plate (70) with a second cylinder head (50) are covered, wherein the first cylinder head (40) have at least one first gas collecting chamber (42) and the second cylinder head (50) have at least one second gas collecting chamber (52).

8. Reciprocating compressor according to claim 7, dad u rch geken nzeich net that the cylinder block (30) has a connecting space (35) which connects the first gas collecting space (42) of the first cylinder head (40) with the second gas collecting space (52) of the second cylinder head (50) connects.

9. Reciprocating compressor according to claim 7 or 8, dad u rch geken nzeich net that the second cylinder head (50) has an outlet opening (54) for compressed air and / or an inlet opening (53) for low-pressure air.

10. Reciprocating compressor according to claim 9, dad u rch geken nzeich net that the first cylinder head (40) has a first gas suction space (41) and the second cylinder head (50) has a second gas suction space (51), the cylinder block (30) having at least one air supply duct (36) which connects the second gas suction space (52) to the first gas suction space (41).

11. Reciprocating compressor according to one of the preceding claims, dad u rch geken nzeich net that at least the engine room (11), in particular at least the engine housing (10), is liquid-cooled, in particular water-cooled.

12. Reciprocating compressor according to claim 11, dad u rch geken nzeich net that a cooling sleeve is provided with cooling channels, which the engine housing (10), the guide block (20), the cylinder block (30), the first valve plate (60), the second Valve plate (70), the first cylinder head (40) and / or the second cylinder head (50), in particular an entire outer circumferential surface of the reciprocating compressor, encased.

13. Reciprocating compressor according to claim 12, dad u rch geken nzeich net that a sound- and / or vibration-absorbing protective cover is provided which extends around the cooling envelope.

14. Reciprocating compressor according to one of the preceding claims, dad u rch geken nzeich net that the first compression chamber (33) and the second compression chamber (34) of the same pressure generating cylinder (31) and / or several first compression chambers (33) and / or several second compression chambers (34) of different pressure generating cylinders (31) are fluidly connected to one another in such a way that a two-stage compression is effected.

15. Compressed air system of a truck, in particular a hybrid or fully electric truck, with a reciprocating compressor according to one of the preceding claims.

16. Use of a reciprocating compressor according to one of the preceding

Claims as a compressed air generator in a compressed air system, in particular a compressed air brake system, of a truck, in particular a hybrid or fully electric truck.