Cooling device for a flow channel

Abstract

The invention relates to a cooling device (8) for a flow channel (6) through which a gaseous fluid can flow, wherein the flow channel (6) is formed radially inside a bushing (10) which has a substantially hollow-cylindrical wall (11) with a radial inner surface (13), a radial outer surface (12), and two axially open end faces (14, 15), and which can be interlockingly and pressure-tightly inserted into an opening (4) of a component (3) or of a sleeve. In order to effectively cool a fluid that is capable of flowing through the flow channel (6), according to the invention the radial inner surface (13) of the bushing (10) has a double conical geometry (30) along its longitudinal extent, the smallest inner diameter of said geometry being located within the maximum longitudinal extent of the bushing (10).

Description

[0001] Cooling device for a flow channel

[0002] The invention relates to a cooling device for a flow channel through which a gaseous fluid can flow, wherein the flow channel is formed radially inwardly on a bushing which has a largely hollow cylindrical wall with a radial inner side, a radial outer side and two axially open end faces, and which can be installed in a receiving opening of a component or a sleeve in a form-fitting and pressure-tight manner.

[0003] DE 10 2017 002 499 A1 discloses a pneumatic reed valve arrangement comprising a reed valve arranged between two pressure chambers. The reed valve has a valve plate resting on one end face of a flow channel connecting the two pressure chambers. A valve opening for a flowing gaseous fluid is formed in the valve plate. An elastic valve reed is attached to the valve plate and is adjustable between a closed position covering the valve opening and an open position uncovering the valve opening. The reed valve acts as a one-way valve or check valve. When excess pressure occurs in the first pressure chamber, it lifts off the valve plate, allowing fluid to flow through the flow channel, and blocks fluid flow in the opposite direction from the second pressure chamber.

[0004] The problem with this known reed valve arrangement, as well as with other similarly constructed reed valve arrangements that connect or separate two pressure chambers, is that a gaseous fluid can heat up considerably during compression and subsequent pressurization in a pressure chamber. The hot fluid flowing through the flow channel connecting the two pressure chambers or being discharged at an outlet can cause the flow channel or outlet and its immediate surroundings, as well as the valve itself, to heat up to such an extent that the maximum service life of the valve is shortened and damage to adjacent components occurs.

[0005] In addition, an increase in the temperature of a gaseous fluid reduces its density, resulting in less fluid flow through a flow channel. In the case of an air compressor, a high outlet temperature can adversely reduce the compressor's flow rate.

[0006] Air compressors with cooling systems are also known. DE 10 2021 121 424 A1, for example, shows such a system. However, it does not provide for direct cooling of a compressed air outlet or a compressed air flow channel.

[0007] Against this background, the invention is based on the object of presenting a cooling device for a flow channel that enables effective cooling of a flowing gaseous fluid. Furthermore, the cooling device is to be formed on or in the region of a hollow cylindrical bushing that can be installed in a compressed air supply system with an air compressor or in the compressor itself, and that radially defines the flow channel.

[0008] This object is achieved with a cooling device having the features of the independent claim. Advantageous embodiments and further developments of this cooling device are defined in the dependent claims.

[0009] In addition, a hollow cylindrical bushing is presented on which this cooling device is formed or arranged.

[0010] The invention accordingly relates to a cooling device for a flow channel through which a gaseous fluid can flow, wherein the flow channel is formed radially on the inside of a bushing which has a largely hollow-cylindrical wall with a radial inner side, a radial outer side, and two axially open end faces, and which can be installed in an opening of a component or a sleeve in a form-fitting and pressure-tight manner. To achieve this object, the radial inner side of the bushing has a double-conical geometry over its longitudinal extent, the smallest inner diameter of which is formed within the maximum longitudinal extent of the bushing.The invention is based on the finding that a compressed, hot, gaseous fluid flowing from a pressure chamber through a flow channel to an outlet or a second pressure chamber hardly cools down without further measures before exiting the outlet or entering the second pressure chamber. As a result, a fluid compressor, i.e., a compressor, can also heat up undesirably over time. The invention solves this problem behind the outlet of the first pressure chamber in a surprisingly simple manner by means of the cooling device comprising a bushing, as described below.

[0011] The bushing can, for example, be a cast part, or manufactured on a lathe or using a conventional 3D printer. For the intended cooling effect, it is advantageous if the bushing is made of a material with a comparatively high thermal conductivity.

[0012] Such a bushing can be installed in an opening of a component, such as an existing flow channel, an outlet channel, or an outlet opening of an air compressor. Alternatively, the bushing can also be initially mounted in a sleeve, which is then installed together with the bushing into the flow channel, the outlet channel, or the outlet opening of an air compressor. Known methods are available for a positive-locking and pressure-tight installation of the bushing in the aforementioned component, such as bonding, pressing, friction welding, or friction stir welding.

[0013] According to the invention, as mentioned, the bushing has a double-conical geometry radially on the inside, radially delimiting the flow channel formed there, the smallest inner diameter of which is formed within the maximum longitudinal extent of the bushing. Accordingly, the bushing can be designed on its inside as a hollow double cone with two conical inner wall sections which face towards each other. From a geometric perspective, the two inner wall sections form two truncated cones whose smaller ends point towards each other. The narrowest inner diameter of the bushing, from a geometric perspective therefore the point at which the two cover surfaces of the truncated cones meet, is preferably located approximately in the middle of the bushing at the transition from the first inner wall section to the second inner wall section. The inner diameter of the bushing continuously widens towards the two axial end faces of the bushing.Surprisingly, this geometry of the bushing has proven to be particularly effective with regard to the intended temperature reduction of a compressed gaseous fluid flowing through this bushing.

[0014] In a basic fluid mechanics analysis of the geometric shape of the flow channel of such a bushing, the first hollow cone section of the double cone, viewed in the flow direction, can be compared in its effect to a subsonic nozzle. The second hollow cone section can be viewed as a subsonic diffuser. In the subsonic nozzle, which tapers in diameter downstream, the flow velocity increases and the pressure of the gaseous fluid decreases. In the subsonic diffuser, which widens further downstream, i.e., in the area of ​​the second hollow cone section, the velocity decreases again and the pressure of the fluid increases.

[0015] The angle of attack α, at which the fluid enters the bushing or its subsonic nozzle, is important. The angle of attack is defined here as the angle between the geometric longitudinal axis of the bushing and the slope of the inner wall of the hollow cone on the inlet side for the flowing fluid. If the angle of attack is greater than a critical angle, the flow breaks off at the inner wall and becomes turbulent. As a result, a highly turbulent flow develops inside the bushing, i.e. in its double-cone-shaped flow channel, with an advantageously selected angle of attack α on the inlet side. Due to this turbulence, the heat exchange of the gaseous fluid increases during its interaction with the inner surface of the double-cone-shaped inner wall of the bushing.Another advantage is that the radially inner double conical shape of the bushing has a larger inner surface for heat exchange than a straight, i.e. purely cylindrical, inner surface.

[0016] According to a very advantageous development of the bushing, it is provided that this and / or the component and / or the sleeve into which the bushing is installed has at least one helical coolant channel which is radially open or radially closed between its two open ends. This enables very different variants, each of which has particular advantages. According to this embodiment of the invention, the bushing can be cooled by means of a coolant which flows through the aforementioned coolant channel. Through the heat exchange of the gaseous fluid flowing through the bushing with the wall of the bushing, which, thanks to the coolant, has a lower temperature than the fluid, heat is extracted from the fluid. The fluid therefore exits the bushing at a reduced temperature.

[0017] Already upstream, i.e., in the area of ​​the subsonic nozzle of the bushing, a temperature reduction of the fluid swirling in the bushing was observed, particularly at supercritical flow angles, due solely to the aforementioned geometric shape of the bushing's inner surface. However, heat dissipation via the coolant channel proves to be particularly advantageous as a complementary feature.

[0018] If, according to another embodiment, the described double-conical inner geometry of the bushing is to be dispensed with in favor of a straight, purely hollow-cylindrical radial inner side of the bushing, a reduction in the gas temperature at the outlet of the bushing can be achieved solely by forming a coolant channel on the bushing through which a coolant flows.

[0019] According to a further development of the double-conical geometry of the radial inner side of the bushing, at least one of the two conical inner wall sections of the bushing can be provided with a radial step, i.e., a radially stepped design. It has been shown that, in particular, a stepped design of the first conical inner wall section, as seen in the flow direction, can further improve the heat exchange between the fluid and the inner wall of the bushing.

[0020] According to one embodiment of the invention, it can be provided that the at least one coolant channel is radially divided into two parts, wherein the bushing has a first surface on its radial outer side with a first channel section formed therein, which is semicircular in cross-section and radially open, and a component surface facing the radial outer side of the bushing with a second channel section formed therein, which is semicircular in cross-section and radially open. In this case, the first channel section on the bushing and the second channel section on the component surface or on the sleeve are arranged in the installed state of the bushing in such a way that they together form the coolant channel with a circular cross-section and radially closed.

[0021] As mentioned, two mutually complementary, i.e. geometrically supplementing, cooling channel sections, namely a first cooling channel section formed on the radial outer side of the bushing and a second cooling channel section formed on the radial inner side of a wall of a component, for example on the inner wall of a receiving bore of an air compressor into which the bushing is to be installed, make it easy to produce a radially closed coolant channel. For this purpose, a helical, radially open first channel section can be formed on the radially outer surface of the bushing. A geometrically matching second helical channel section can be formed on the radially inward-facing wall of the component that is directly adjacent to it when installed. The number of turns of the helix can advantageously be adapted to the geometric dimensions of the bushing or the component.

[0022] The bushing can be firmly integrated into the component in question using conventional joining techniques such as friction welding, press fitting, or bonding, creating a pressure-tight, radially closed, and open-ended coolant channel. These joining techniques have the advantage of securely and permanently connecting two components made of the same or different materials.

[0023] It should be noted at this point that a circular cross-section of the coolant channel, while advantageous from a manufacturing perspective, is not absolutely necessary. Alternatively, other cross-sectional shapes can also be used, such as a rectangular or V-shaped cross-sectional geometry.

[0024] According to another embodiment of the cooling device having the features of the invention, it can be provided that the at least one coolant channel is radially formed in one piece, wherein the bushing has a surface on its radial outer side with a channel section formed therein that is semicircular in cross-section and radially open, and wherein a flat surface of the component or sleeve facing the radial outer side of the bushing covers the semicircular channel section radially outward. As a result, the channel section on the bushing and the flat surface of the component or sleeve together form the coolant channel that is semicircular in cross-section and radially closed when the bushing is installed.

[0025] The semicircular cross-section of the coolant channel formed on the bushing requires no additional machining of the existing component to which the bushing is to be attached, for example, when installed in the outlet port of an air compressor. Installation of the bushing is simple because there are no two channel sections that need to be precisely aligned. This reduces costs both in the manufacturing of the component and in the assembly of the bushing.

[0026] According to a further variant, it can be provided that the at least one coolant channel is designed as a radially closed channel, i.e., as a tubular or hose-like channel arranged on the radial inside of the bushing. Accordingly, the coolant channel can be formed or attached directly on the radial inside of the bushing. As a result, heat transfer from the gaseous fluid to the coolant advantageously takes place directly via the coolant channel. Furthermore, the exposed windings of the coolant channel can advantageously enhance the generation of turbulence in the flow channel of the bushing.

[0027] Another embodiment of the bushing provides that the at least one coolant channel, which is radially closed between its axial ends, has the smallest possible distance from the radial inside of the bushing with regard to its axial and radial course in the material of the bushing. The coolant channel arranged in this way can therefore bring the coolant as close as possible to the flowing gaseous fluid. Because the coolant channel is arranged as close as possible to the radial inside of the bushing, an almost direct and particularly effective heat transfer of the fluid in the region of the inside of the bushing is achieved. In particular, in a design of the bushing with a double-conical internal geometry, the arrangement of the coolant channel can be adapted axially and radially, i.e. it can also run in a double-conical shape.

[0028] According to a further embodiment of the cooling device according to the invention, which is technically very easy to implement, it can be provided that the at least one coolant channel is formed radially in one piece, that the bushing has a flat surface on its radial outer side, and that a component surface facing the radial outer side of the bushing has a channel section formed therein that is semicircular in cross-section and open radially inward. As a result, the channel section of the component or sleeve and the flat surface of the bushing together form the coolant channel with a semicircular cross-section and radially closed when the bushing is installed. The coolant channel with the semicircular cross-section formed only on the component eliminates the need for corresponding complementary machining of the bushing.Mounting the bushing into a receiving opening in the component is therefore simple because there are no two channel sections that need to be precisely aligned. This also reduces costs in the manufacturing of the component and in the assembly of the bushing.

[0029] Furthermore, it can be provided that the bushing has a lamella valve arranged on one of the two axial end faces of the bushing. The lamella valve has a valve opening at which a lamella is arranged, which is resiliently preloaded in the closing direction of the lamella valve. This ensures that the lamella can be pivoted up from the valve opening by a pressure force of a gaseous fluid acting on the lamella counter to the closing direction, which pressure force at least exceeds the spring force of the lamella, in order to open the valve opening for a gaseous fluid flowing through it, and otherwise rests against the valve opening and keeps it closed.

[0030] Accordingly, the bushing with the cooling device can advantageously be arranged between two pressure chambers or in an outlet opening of a pressure chamber and provided with a valve arrangement, such as a reed valve. The bushing with the cooling device can, for example, be installed in an air compressor with a pressure-controlled one-way valve on the outlet side in order to reduce the temperature of the gas compressed therein at the outlet. The previously described turbulence effect on heat transfer can advantageously be further enhanced by the fact that, due to a reed of a reed valve that is pre-tensioned against the valve opening, a spring force opposing the pressure force of the fluid and possibly also a counterpressure in the second pressure chamber must first be overcome before the reed can lift off from the valve opening.In this context, it can be provided that the reed valve has a valve seat in the form of an annular, axial and radial enlargement of the bushing, such as a flange and / or in the form of an elastic sealing element arranged on the bushing or on a component into which the bushing can be installed.

[0031] In principle, a special valve seat can be dispensed with in the reed valve. However, in the pre-tensioned state, the reed can rest against a wall that defines the valve opening. Nevertheless, it is advantageous if the reed valve has its own, integrated valve seat in order to achieve the lowest possible leakage rate of the valve and to minimize noise development and friction of the reed during operation. For this purpose, for example, a flange with a sealing surface can be formed on the end face of the bushing, against which the reed rests tightly in its closed position. The sealing surface can be made of a sound-insulating material. Alternatively, a sealing element made of a vulcanized elastomer or a polymer can be provided. Such a sealing element can, for example, be an O-ring, which can be inserted into a groove on the end face that defines the valve opening.

[0032] Also claimed is a bushing advantageously designed for the described cooling device. This bushing has a largely hollow-cylindrical wall with a radial inner side, a radial outer side, and two axially open end faces, which can be installed in a receiving opening of a component or a sleeve in a form-fitting and pressure-tight manner. According to the invention, this bushing is characterized in that it has a double-conical geometry on the radial inside, the smallest inner diameter of which is formed within the maximum longitudinal extent of the bushing. The advantages of this double-conical geometry of the inner surface of the bushing with regard to heat transfer from the gaseous fluid to the material of the bushing have been described in detail above.

[0033] Also claimed is a further bushing advantageously designed for the described cooling device, which has a largely hollow-cylindrical wall with a radial inner side, a radial outer side, and two axially open end faces, which can be installed in a receiving opening of a component or a sleeve in a form-fitting and pressure-tight manner. This bushing is characterized in that it has at least one helical coolant channel, which is radially open or radially closed between its two open ends. Its advantages have also been described many times above.

[0034] Finally, the invention also relates to an air compressor for a compressed air supply system of a vehicle, having a compressed air outlet for discharging the air compressed in the air compressor, wherein the compressed air outlet has a cooling device on or in the region of the bushing according to at least one of the device claims.

[0035] The invention will be further explained below with reference to some embodiments shown in the accompanying drawings.

[0036] Fig. 1 is a schematic longitudinal section through a region of an air compressor with a cooling device for a flow channel, which is formed in a bushing, according to a first embodiment of the invention, Fig. 2 is an enlarged perspective view of the bushing according to Fig. 1, Fig. 3 is the air compressor according to Fig. 1 with a cooling device and bushing according to a second embodiment, Fig. 4 is the air compressor according to Fig. 1 with a cooling device and bushing according to a third embodiment, Fig. 5 is the air compressor according to Fig. 1 with a cooling device and bushing according to a fourth embodiment, Fig. 6 is the air compressor according to Fig. 1 with a cooling device and bushing according to a fifth embodiment, Fig. 7 is the air compressor according to Fig. 1 with a cooling device and bushing according to a sixth embodiment, and Fig. 8 is the air compressor according to Fig. 1 with a cooling device and bushing according to a seventh embodiment.

[0037] Some components in the figures are the same, so they are given the same reference numerals.

[0038] Accordingly, Fig. 1 shows a portion of an air compressor 1 in which a bore-like receiving opening 4 is formed in a wall of its component 3. The air compressor 1, shown only in a schematically simplified form and in a section, can be, for example, a scroll compressor for generating compressed air in a compressed air supply system of a commercial vehicle. Such a pressure supply system serves, for example, to supply compressed air for a pneumatic braking system and / or for an air suspension device.

[0039] The operation of scroll-type air compressors is well known. In a common design, two spirals are arranged axially and radially within one another, one of which can move around the other in an orbit. The movable spiral, which can orbit the stationary spiral, is deflected by an eccentric drive in a plane perpendicular to a central axis. The two spirals mesh with each other, with spiral flights formed between the spirals narrowing progressively radially inward. As the drive rotates, gas drawn in from the outside is further compressed within the spiral flights, and the compressed gas is finally discharged through a central outlet for further use.

[0040] According to Fig. 1, the air compressor 1 has a first pressure chamber 2, for example in the form of a partially illustrated spiral passage, in which air drawn in from the outside is continuously compressed during operation of the air compressor 1 and inevitably heats up in the process. The first pressure chamber 2 is delimited by a component 3 of the air compressor 1 (not described in detail). Formed in this component 3 is the aforementioned receiving opening 4, through which the compressed air can flow out in known air compressors. In this example, a second pressure chamber 5 is provided downstream outside the air compressor 1. The two pressure chambers 2, 5 are pneumatically connectable to one another via the aforementioned receiving opening 4 and a reed valve 16 (to be described later). A bushing 10 designed according to the invention is firmly and pressure-tightly installed in the receiving opening 4, for example by means of a friction welding process.

[0041] As can be seen more clearly in Fig. 2, the bushing 10 has a largely hollow-cylindrical wall 11 with a radial outer side 12, a radial inner side 13, an axially open first end face 14 facing the first pressure chamber 2, and an axially open second end face 15 facing the second pressure chamber 5. The cavity of the bushing 10, defined by the radial inner side 13 of the bushing 10, forms a flow channel 6, more clearly visible in Fig. 1, for compressed air flowing out of the air compressor 1. The bushing 10 will be described in more detail below.

[0042] The reed valve 16 is arranged on the second end face 15 of the bushing 10 on the side of the second pressure chamber 5. The second end face 15 of the bushing 10 forms a valve opening 17 for the reed valve 16. In the example shown in Fig. 1, the bushing 10 has an annular enlargement 18 in the form of a flange at the valve opening 17, which delimits the latter and extends radially outward. The free end of the annular enlargement 18 on the end face is designed as a valve seat 19 for a reed 20 of the reed valve 16.

[0043] The lamella 20 is designed as a thin, elastic plate, which is fastened on one side by its radial edge section 21 to the annular enlargement 18 of the bushing 10, radially outside the valve opening 17. Furthermore, a rigid lamella retainer 22 is fastened to the component 3, which limits the pivoting path of the lamella 20 in the opening direction. In the closed position shown in Fig. 1, the lamella 20 rests tightly against the valve seat 19 with preload, thereby closing the valve opening 17. Also shown in dashed lines is an open position of the lamella valve 16, in which the lamella 20 rests against the lamella retainer 22. A small arrow drawn there illustrates an opening path of the lamella 20.

[0044] Not shown is an optional elastomeric sealing element, such as an O-ring, which can be inserted into a groove formed in the annular enlargement 18. In its closed position, the lamella 20 can rest against such an elastomeric sealing element with preload. This can increase the tightness of the lamella valve 16 in the closed position and minimize the noise generated when the lamella 20 springs back from the open position to the closed position.

[0045] The lamella valve 16 functions as follows: When there is excess pressure in the first pressure chamber 2, the compressed air generated in the air compressor 1, flowing from left to right in Fig. 1, lifts the lamella 20 from the valve seat 19 and releases the valve opening 17, allowing the compressed air to flow unhindered. When the air compressor 1 is switched off or when there is excess pressure in the second pressure chamber 5, the lamella 20 is pressed against the valve seat 19 by its preload and, if applicable, by the pressure in the second pressure chamber 5, so that the valve opening 17 is closed and an air flow from right to left in Fig. 1 would be blocked.

[0046] Without further measures, the compressed air generated in the air compressor 1 and significantly heated by compression could, over time, significantly heat up a compressed air outlet of the air compressor 1 and its adjacent surroundings. Furthermore, extremely heated compressed air can be detrimental to devices that come into contact with it. The invention addresses this issue by cooling the flowing compressed air using a special cooling device.

[0047] According to the first embodiment of the cooling device 8.1 shown in Fig. 1, the radial inner side 13 of the bushing 10 has a double-conical geometry 30 with a first conical inner wall section 31 in a region facing the first pressure chamber 2 and a second conical inner wall section 32 in a region facing the second pressure chamber 5. The smallest inner diameter of this double-conical geometry 30 is preferably located approximately centrally within the longitudinal extent of the bushing 10. The two inner wall sections 31, 32 each have an opening angle α with respect to the geometric longitudinal axis 33 of the bushing 10. The opening angle α is particularly important on the compressor side and is selected such that a turbulent flow of the fluid is generated or at least intensified within the double-conical geometry 30.

[0048] The cooling function of the bushing 10 shown is therefore as follows: The compressed air generated in the air compressor 1 flows through the bushing 10 from left to right in Fig. 1, with the lamella 20 of the lamella valve 16 having lifted off the valve opening 17 due to the pneumatic pressure force. The double-conical geometry 30 on the radial inner side 13 of the bushing 10 makes the flow turbulent, or at least further intensifies existing turbulence. Due to the turbulence and the enlarged inner wall surface compared to a purely cylindrical inner side 13 of a bushing 10, the heat transfer of the fluid into the material of the bushing 10 and from there into the wall 3 of the air compressor 1 is increased, whereby the fluid is cooled more than previously possible. To further improve the cooling effect, the cooling device 8.1 according to Fig.1, in addition to the special geometry of the radial inner side 13 of the bushing 10, has a coolant channel 25 that is radially closed between its two open ends. The open ends of the coolant channel 25 can be connected, for example, to a cooling system of a commercial vehicle, and the coolant can flow continuously through it. The coolant channel 25 preferably has a helical or screw-shaped geometry.

[0049] In the embodiment shown in Fig. 1, the coolant channel 25 is radially formed in two parts. The bushing 10 has, on its radial outer side 12, a first channel section 26 which is semicircular in cross-section and open radially outwards. In addition, a second channel section 27 which is compatible with the first channel section 26 and has a semicircular cross-section and is open radially inwards is formed on the radially inward-facing component surface 28 of the receiving opening 4 of the component 3. When the bushing 10 is installed, the first channel section 26 on the bushing 10 and the second channel section 27 on the receiving opening 4 of the component 3 together form the coolant channel 25 which is circular in cross-section and radially closed. During operation, the coolant flowing through the coolant channel 25 absorbs heat from the bushing and the component 3 and conducts it to a cooler, where the heat is dissipated into the ambient air.

[0050] Fig. 3 shows the air compressor 1 according to Fig. 1 with a substantially identical second bushing 40 and cooling device 8.2. The bushing 40 is formed without the annular radial enlargement 18 with the valve seat 19. Instead, the lamella 20 of the lamella valve 16 simply rests against a flat edge surface 41 at a front end of the component 3 radially outside the bushing 40.

[0051] Fig. 4 shows a further embodiment of a cooling device 8.3 with a bushing 45. This cooling device 8.3 has the described two-part cooling channel 25, the double-conical geometry of the radial inner side 13 of the bushing 45, and additionally a radial step 48 of the two conical inner wall sections 46, 47. Not shown is an alternative embodiment in which only the first, inlet-side conical inner wall section 46 is stepped. The gaseous fluid flows, as already described, from left to right over this step 48. At the radial step 48, the flow is additionally strongly swirled, further improving the heat exchange.

[0052] Fig. 5 shows another embodiment of the air compressor 1 with a cooling device 8.4, which has a bushing 50 with a double-conical radial inner side 13 and a special cooling channel 51. This cooling channel 51 also extends helically on the radial outer side 12 of the bushing 50, but has a semicircular cross-sectional geometry. This cooling device 8.4 therefore only has the previously described first channel section 26, which is semicircular in cross-section and radially open, on the radial outer side 12 of the bushing 50. A second radial channel section is therefore not present here. When this bushing 50 is installed in the component 3 of the air compressor 1, the channel section 26 of the bushing 50, which is open radially outwards, is covered by a radially flat surface 52 of the receiving opening 4 of the component 3, so that the bushing-side coolant channel 51, which is semicircular in cross-section, is radially closed in a pressure-tight manner.

[0053] Fig. 6 shows a further embodiment of the air compressor 1 with a cooling device 8.5, which has a bushing 70 with a double-conical radial inner side 13 and a separate, circular-cross-sectionally fifth coolant channel 71. This coolant channel 71 is arranged on the radial inner side 13 of the bushing 70, where it is in direct contact with the gaseous fluid flowing out of the air compressor 1 or the first pressure chamber 2. Furthermore, in this embodiment, the bushing 70 is sealed in the receiving opening 4 of the component 3 with a first O-ring 72 against the first pressure chamber 2 and with a second O-ring 73 against the second pressure chamber 5.

[0054] Fig. 7 shows an air compressor 1 with a cooling device 8.6, in which a bushing 60, as already described, has a double-conical radial inner side 13. In this embodiment, the coolant channel 61 of the cooling device 8.6 is completely integrated into the wall 11 of the bushing 60 and is arranged as radially inward as possible without penetrating the wall 11 of the bushing 60. The radially outer side 12 of the bushing 60 and the radially inner surface 52 of the receiving opening 4 are flat. Fig. 8 shows a final embodiment of the air compressor 1 with a cooling device 8.7, which has a bushing 80 with a double-conical radial inner side 13. The bushing 80 has a flat surface 57 on its radially cylindrical outer side 12.However, a helical coolant channel 56 with a semicircular cross-section and radially inwardly open is formed on the radially inward-facing component surface 29 of component 3. When this bushing 80 is installed in the receiving opening 4 of component 3 of the air compressor 1, the radially inwardly open channel section 56 in the receiving opening 4 of component 3 is radially covered by the radially outer flat surface 57 of the bushing 80, so that the component-side coolant channel 56, which has a semicircular cross-section, is radially closed in a pressure-tight manner.

[0055] List of reference symbols (part of the description)

[0056] 1 air compressor

[0057] 2 First pressure chamber

[0058] 3 Component of the air compressor

[0059] 4 Receiving opening in component 3

[0060] 5 Second pressure chamber

[0061] 6 flow channel

[0062] 8.1 Cooling device (first embodiment)

[0063] 8.2 Cooling device (second embodiment)

[0064] 8.3 Cooling device (third embodiment)

[0065] 8.4 Cooling device (fourth embodiment)

[0066] 8.5 Cooling device (fifth embodiment)

[0067] 8.6 Cooling device (sixth embodiment)

[0068] 8.7 Cooling device (seventh embodiment)

[0069] 10 socket (first embodiment)

[0070] 11 Wall of the socket

[0071] 12 Radial outside of the bushing

[0072] 13 Radial inside of the bushing

[0073] 14 First end face of the socket

[0074] 15 Second end face of the socket

[0075] 16 lamella valve

[0076] 17 Valve opening

[0077] 18 Ring-shaped enlargement of the socket 10

[0078] 19 Valve seat of bushing 10

[0079] 20 slats

[0080] 21 Edge section of the slat

[0081] 22 slat retainers

[0082] 25 Coolant channel of bushing 10

[0083] 26 First radial channel section of the coolant channel 25

[0084] 27 Second radial channel section of the coolant channel 25

[0085] 28 Component surface with radial channel section 26 of the coolant channel 25

[0086] 29 Component surface with coolant channel 56

[0087] 30 Double-conical geometry of the bushing

[0088] 31 First conical inner wall section of the bushing 10 32 Second conical inner wall section of the bushing 10

[0089] 33 Geometric longitudinal axis of the bushing

[0090] 40 socket (second embodiment)

[0091] 41 Flat front edge surface on component 3

[0092] 45 socket (third embodiment)

[0093] 46 First conical inner wall section of the bushing 45

[0094] 47 Second conical inner wall section of the bushing 45

[0095] 48 Gradation of the inner wall sections 46, 47 of the bushing 45

[0096] 50 socket (fourth embodiment)

[0097] 51 Coolant channel of the bushing 50

[0098] 52 Flat surface at the receiving opening 4

[0099] 56 Coolant channel of the bushing 80

[0100] 57 Flat surface on the socket 80

[0101] 60 socket (sixth embodiment)

[0102] 61 Coolant channel of the bushing 60

[0103] 70 socket (fifth embodiment)

[0104] 71 Coolant channel of the bushing 70

[0105] 72 First O-ring

[0106] 73 Second O-ring

[0107] 80 Bushing (seventh embodiment) a Angle of attack, opening angle

Claims

Patent claims 1. Cooling device (8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7) for a flow channel (6) through which a gaseous fluid can flow, wherein the flow channel (6) is formed radially inwardly on a bushing (10, 40, 45, 50, 60, 70, 80) which has a largely hollow cylindrical wall (11) with a radial inner side (13), a radial outer side (12) and two axially open end faces (14, 15), and which can be installed in a receiving opening (4) of a component (3) or a sleeve in a form-fitting and pressure-tight manner, characterized in that the radial inner side (13) of the bushing (10, 40, 45, 50, 60, 70, 80) over whose longitudinal extent has a double-conical geometry (30), the smallest inner diameter of which is formed within the maximum longitudinal extent of the bushing (10, 40, 45, 50, 60, 70, 80).

2. Cooling device (8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7) according to claim 1, characterized in that the bushing (10, 40, 45, 50, 60, 70, 80) and / or the component (3) and / or the sleeve has at least one helical coolant channel (25, 51, 56, 61, 71) which is designed to be radially open or radially closed between its two open ends.

3. Cooling device (8.3) according to claim 1 or 2, characterized in that at least one of the two conical inner wall sections (46, 47) of the bushing (45) has a radial step (48).

4. Cooling device (8.1, 8.2, 8.3) according to one of claims 1 to 3, characterized in that the at least one coolant channel (25) is radially divided into two parts, wherein the bushing (10, 40, 45) has on its radial outer side (12) a first surface with a first channel section (26) formed therein, which is semicircular in cross section and radially open, and a component surface (28) facing the radial outer side (12) of the bushing (10, 40, 45) with a second channel section (27) formed therein, which is semicircular in cross section and radially open, wherein the first channel section (26) is arranged on the bushing (10, 40, 45) and the second channel section (27) is arranged on the component surface (28) or on the sleeve in the installed state of the bushing (10, 40, 45) in such a way that they together form the coolant channel which is circular in cross section and radially closed. (25) form.

5. Cooling device (8.4) according to one of claims 1 to 3, characterized in that the at least one coolant channel (51) is formed radially in one piece, wherein the bushing (50) has on its radial outer side (12) a surface with a channel section (26) formed therein that is semicircular in cross section and radially open, and wherein a flat surface (52) of the component (3) or of the sleeve facing the radial outer side (12) of the bushing (50) covers the semicircular channel section (26) radially outwards, so that the channel section (26) on the bushing (50) and the flat surface (52) of the component (3) or of the sleeve, when the bushing (50) is installed, together form the coolant channel (51) that is semicircular in cross section and radially closed.

6. Cooling device (8.5) according to one of claims 1 to 3, characterized in that the at least one coolant channel (71) is designed as a tubular channel which is arranged on the radial inner side (13) of the bushing (70).

7. Cooling device (8.6) according to one of claims 1 to 3, characterized in that the at least one coolant channel (61) which is radially closed between its axial ends has the smallest possible distance from the radial inner side (13) of the bushing (60) with regard to its axial and radial course in the material of the bushing (60).

8. Cooling device (8.7) according to one of claims 1 to 3, characterized in that the at least one coolant channel (56) is radially formed in one piece, that the bushing (80) has a flat surface (57) on its radial outer side (12), that a component surface (29) facing the radial outer side (12) of the bushing (80) has a channel section (27) formed therein, which is semicircular in cross section and open radially inwards, so that the channel section (27) of the component (3) or of the sleeve and the flat surface (57) of the bushing (80) together form the radially semicircular in cross section and coolant channel (56) in the installed state of the bushing (80).

9. Cooling device (8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7) according to one of claims 1 to 8, characterized in that the bushing (10, 40, 45, 50, 60, 70, 80) has a lamella valve (16) which is arranged on one of the two axial end faces (14, 15) of the bushing (10, 40, 45, 50, 60, 70, 80), wherein the lamella valve (16) has a valve opening opening (17) on which a lamella (20) is arranged, which is resiliently prestressed in the closing direction of the lamella valve (16), so that the lamella (20) can be pivoted up from the valve opening (17) by a pressure force of a gaseous fluid acting on the lamella (20) counter to the closing direction, which pressure force at least exceeds the spring force of the lamella (20), in order to open the valve opening (17) for a gaseous fluid flowing through, and otherwise rests against the valve opening (17) and keeps it closed.

10. Cooling device (8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7) according to claim 9, characterized in that the lamella valve (16) has a valve seat (19) in the form of an annular axial and radial enlargement (18) of the bushing (10, 45, 50, 60, 70, 80) or on a component 3 into which the bushing (10, 45, 50, 60, 70, 80) can be installed.

11. Bushing (10, 40, 45, 50, 60, 70, 80), having a largely hollow cylindrical wall (11) with a radial inner side (13), a radial outer side (12) and two axially open end faces (14, 15), which can be installed in a form-fitting and pressure-tight manner in a receiving opening (4) of a component (3) or a sleeve, characterized in that the bushing (10, 40, 45, 50, 60, 70, 80) has a double-conical geometry (30) radially on the inside, the smallest inner diameter of which is formed within the maximum longitudinal extent of the bushing (10, 40, 45, 50, 80, 60, 70).

12. Bushing (10, 40, 45, 50, 60, 70, 80), having a largely hollow cylindrical wall (11) with a radial inner side (13), a radial outer side (12) and two axially open end faces (14, 15), which can be installed in a positive-locking and pressure-tight manner in a receiving opening (4) of a component (3) or a sleeve, characterized in that the bushing (10, 40, 45, 50, 60, 70) has at least one helical coolant channel (25, 51, 56, 61, 71) which is designed to be radially open or radially closed between its two open ends.

13. Air compressor (1) for a compressed air supply system of a vehicle, with a compressed air outlet for discharging the air compressed in the air compressor (1), wherein the compressed air outlet has a cooling device (8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7) according to one of the device claims.

Images