EP1484568A2 - Heat exchange apparatus - Google Patents

Abstract

The radiator is provided by a hollow body (10) through which the engine coolant is passed and over which the outside air flows, with the hollow body being rotated about an axis passing through an axial inlet opening (30) and an aligned axial outlet opening (32) for the engine coolant, e.g. via an asynchronous electric motor.

Description

The invention relates to a device for heat exchange between a first fluid medium, preferably a liquid such as B. water, coolant or oil, and a second fluid medium, preferably a gas such as B. ambient air. The device contains one Hollow body through which one of the two media flows and its Outside the other of the two media is exposed.

Such heat exchange devices are, for example, as Radiator used in vehicles. DE-A-101 39 315 describes for example one arranged in an engine cooling circuit Heat exchanger. With such heat exchangers Cooling liquid to be cooled through the pipe system fixed, thin-walled cooler promoted. The cooler is often flat and cuboid and contains Through openings through the means of a fan Ambient air is promoted. The cooler separates the two Media air and coolant. To ensure good heat transfer to achieve is a high flow rate of the two Media coolant and ambient air, good Thermal conductivity of the cooler and a large surface of the Cooler advantageous. Because the heat transfer between one Liquid and a solid usually a great deal is easier than between a gas and one Solid state, the latter determines the one for transferring a certain amount of heat necessary dimensions of the cooler. you will therefore try to rip the surfaces of the radiator and the like to enlarge. That kind of Surface enlargement in particular leads to agricultural applications where the ambient air is very dirty, to the risk that the cooler is relative quickly soiled and thus the heat transfer deteriorated.

To the air through the passage openings of the heat exchanger to promote, for example, a fan is used. The amount of air conveyed, the flow velocity and the Temperature difference between the outside of the radiator and the Ambient air largely determines the thermal output of the Heat exchanger. To the liquid through the heat exchanger too pump is used.

The disadvantage of these heat exchangers is the need for one large surface area in contact with the ambient air standing heat exchanger side. This surface is significant larger than the surface that is in with the liquid Touch. Because of the large surfaces required there is a high space requirement for the heat exchanger. It is also a significant amount of energy is required to power the two Media, especially the ambient air, through the heat exchanger to promote. The risk of contamination is particularly in the agricultural field significantly. There is a big one Construction effort caused by the need for a Pump, a fan and a cooler.

The object underlying the invention is seen in a heat exchanger device of the type mentioned above to train that the problems mentioned are overcome. In particular, the device for heat exchange comparatively small dimensions with high power density exhibit. You should comparatively little operational energy require few inexpensive components and the risk reduce pollution.

The object is achieved by the teaching of Claim 1 solved. Further advantageous configurations and further developments of the invention result from the subclaims out.

The inventive device for heat exchange between a first fluid medium, preferably one Liquid such as B. water, coolant or oil, and one second fluid medium, preferably a gas such as. B. ambient air, contains a hollow body through which Inside one of the two media flows and the outside is exposed to the other of the two media. Even if the Media are freely selectable, that is through the Hollow body flowing medium preferably a liquid and the medium flowing around the hollow body is the outside air. The Invention solves the aforementioned problem in that the Flow velocity of the medium flowing around the hollow body, especially the ambient air compared to the prior art is increased drastically by acting as a hollow body trained cooler is not fixed, but about an axis rotates.

Due to the high possible peripheral speed of around The axis of the rotating hollow body is high Flow velocities in the area of its peripheral surface, whereby an intimate heat exchange takes place. This leaves the performance of the heat exchange increase, so that the heat exchange device according to the invention compared to previously conventional heat exchangers have a reduced surface area at high Has power density, which is also the required Reduced space requirements. The risk of pollution decreases because the dirt particles are no longer in narrow passages fix but be blown away. Due to the structure as rotating structure it will still be possible to use the functions of cooler, pump and fan in one structural unit summarize, which results in a simple construction, separate drives for pumps and fans are not required can and the comparatively low operating energies requires.

The hollow body is used for good heat transfer preferably made of aluminum, for example cast aluminum.

The hollow body preferably has an axial inlet opening and an axial outlet opening for the medium flowing through on, the one medium, especially the cooling or Heating fluid, through a coaxial to the axis of rotation of the Hollow body aligned first tube in the hollow body enters and through a second tube coaxial with the first tube emerges again.

It is advantageous if the inlet opening and / or the outlet opening in a fixed, at least sectionally tubular inlet channel or in a fixed, at least partially tubular trained outlet channel is formed. The hollow body is supported by at least one pivot bearing on the Entry channel and / or on the exit channel rotatable from and is possibly by seals against the Sealed inlet duct and / or the outlet duct. The Seals prevent the fluid flowing through the hollow body Medium escapes from the inside of the hollow body and that the medium flowing around the hollow body penetrates into the hollow body.

According to a further advantageous embodiment of the invention can also replace the first tube and the second tube only undivided tubular component can be used, that extends axially through the hollow body and a entry opening lying outside the hollow body and a Has outlet opening. In its inside the hollow body the tubular component contains passages, through which the medium flowing through the tubular component in can enter and exit the hollow body, so that the interior of the hollow body is washed by the medium.

It can also be advantageous to feed and discharge the Medium flowing through the hollow body coaxially on one side perform. Here is only one seal and one one-sided storage required. For this purpose, a inner and outer tubes are used which are coaxial in the axis of rotation are arranged and between which an annular channel is trained. The medium can be fed via the inner Pipe and the discharge of the medium can be via the ring channel respectively. Of course it is also possible to change the direction of flow reverse to perform.

In the case of one-sided supply and discharge of the medium it be beneficial between the inlet and the outlet Overflow openings or channels to provide a direct Passage of a partial flow of the medium from the Allow entry opening to exit opening. In doing so the cross-sectional areas of inlet and outlet designed so that due to different flow velocities in the Inlet and outlet part of the flowing medium from the Inlet line flows directly into the outlet line and not through the inside of the hollow body. In a particularly advantageous way In this case, at least a section of the return line can be designed as an injector, so that the arrangement as Suction jet pump works. The constructive advantage is an im Area of the bearing and sealing point reduced diameter same volume flow in the outer cooling circuit.

A favorable design detail of the invention is included therein see that in an axially outer region of the hollow body Filling opening is provided by a closure is lockable. The can be filled through the filling opening Fill and empty the hollow body and the entire cooling system. For the purpose of filling, the hollow body is placed in one position rotated in the filling opening essentially upwards shows and thus occupies the highest position. For emptying the hollow body rotates until the filling opening is at the bottom. By appropriate design of the cooling system and the choice of Diameter of the hollow body can be achieved so that a complete filling and emptying with just one opening is possible using only one closure. Around The axial distance between the filling opening can also be adjusted Connection piece between the hollow body and the filling opening to be ordered.

According to a further advantageous embodiment of the invention is an elastic membrane inside the hollow body arranged that part of the enclosed in the hollow body Volume separated from the medium (e.g. liquid). The The membrane may be prestressed. For the preload a spring or a gas filling is suitable, for example. The variable preloaded part serves to change the volume of the to balance medium flowing through the hollow body.

In a preferred development of the invention Inside the rotating hollow body a pump wheel rigid attached. The bearing of the pump wheel is in advantageously with the bearings of the hollow body taken over, so that no additional storage of the pump wheel is required. The pump wheel is used to promote the the flowing medium (e.g. liquid).

Furthermore, it is advantageous to rigidly attach the hollow body with a to connect to the rotating outer fan wheel. Here too can the storage of the fan wheel in an advantageous manner the bearings of the hollow body are taken over, so that too no additional storage is provided for the fan wheel got to. The pump wheel serves to promote the outside of the hollow body flowing medium (e.g. ambient air).

According to a preferred development of the invention inside the hollow body and / or outside the hollow body at least one fixed stator or guide housing intended. The fixed idler wheel or idler housing can for example in the direction of flow in front of or behind the Pump wheel or the fan wheel can be arranged. The guide wheel and the guide housing act with the associated impeller or Fan wheel together for an optimal flow of the to ensure the respective medium. When using a it can be arranged within the hollow body be necessary to form the hollow body in several parts, so that the hollow body can be disassembled in order to assemble the To allow stator.

To increase the surface area involved in heat exchange proposes a preferred development of the invention that on a (preferably cylindrical) outer surface and / or a (preferably cylindrical) inner lateral surface the hollow body elevations and depressions are provided.

It is particularly advantageous to view these surveys as oblique Rotationally arranged (helical) blades train so that they have the function of promoting the respective medium (e.g. ambient air or liquid) for Can take over part or all of it. In this case too a fixed diffuser or diffuser in the direction of flow be arranged in front of and / or behind the blades.

The hollow body can be driven in an advantageous manner known elements such as B. spur gears, flat belts, Timing belts, V-belts, V-ribbed belts or roller chains respectively. For this purpose there are drive means on the hollow body intended to initiate a torque.

According to a further preferred embodiment of the invention it is also possible to electrically drive the hollow body and in particular rigidly with the rotor of an electric motor connect. The task of storing the electric motor can preferably taken over by the bearings of the hollow body become.

In a preferred embodiment of the invention Hollow body connected to the rotor of an asynchronous motor and at the same time forms a short-circuit ring of the asynchronous motor. Furthermore, it is advantageous if an as on the hollow body Short-circuit cage for the asynchronous motor approach is molded. It is advantageous to use the hollow body with the as a short-circuit cage approach in one piece To produce cast aluminum. Furthermore, a second can Short-circuit ring cast at the same time during manufacture become.

The stator of the asynchronous motor is preferably in a housing made of a good heat-conducting material, e.g. B. cast aluminum, used, the housing in good heat-conducting contact with the medium (liquid) flowing through the hollow body. The rotor of the asynchronous motor is connected to the through the medium (liquid) flowing also very much well chilled.

The asynchronous motor can be connected to a device which allows the variable speed asynchronous motor to let it run, to stop completely and / or that Reverse direction of rotation. This device is preferably a Frequency converter.

It is furthermore advantageous to at least maintain the temperature to capture one of the media. For example, the Temperature of the first medium at the entry point of the Hollow body (e.g. at the liquid inlet) and / or at the Exit point of the hollow body (e.g. at the liquid return) are detected by temperature sensors. It is alternative or cumulative also possible the temperature of the second medium, the flows around the outside of the hollow body (e.g. air flow) Detect temperature sensors. The temperature readings will be a control unit supplied depending on the Temperature measured values the speed of the asynchronous motor and thus controls the hollow body.

In a preferred embodiment of the invention Hollow body, possibly with its pump wheel, fan wheel or with its elevations and specializations, in particular Paddle wheels and possibly with the drive means as well with the short-circuit cage and the short-circuit ring one Electric motor essentially formed in one piece. This one-piece component can be by casting, die casting, injection molding, Forging, sintering from a good heat-conducting material, such as Aluminum, an aluminum alloy, copper, a Copper alloy, zinc, a zinc alloy, glass or carbon fiber reinforced plastic or ceramic become.

Based on the drawing, the embodiments of the invention shows, the invention and further advantages are below and advantageous developments and refinements of Invention described and explained in more detail.

Fig. 1

die schematische Schnittdarstellung einer ersten erfindungsgemäßen Wärmeaustauschvorrichtung, welche durch einen Asynchronmotor angetrieben wird,

Fig. 2

die Seitenansicht des Hohlkörpers einer erfindungsgemäßen Wärmeaustauschvorrichtung,

Fig. 3

die schematische Schnittdarstellung einer zweiten erfindungsgemäßen Wärmeaustauschvorrichtung mit einem Lüfterrad,

Fig. 4

die schematische Schnittdarstellung einer dritten erfindungsgemäßen Wärmeaustauschvorrichtung mit einem internen Pumpenrad und

Fig. 5

die schematische Schnittdarstellung einer vierten erfindungsgemäßen Wärmeaustauschvorrichtung mit einseitiger Zu- und Abfuhr des durch den Hohlkörper strömenden Mediums.

It shows:

Fig. 1

2 shows the schematic sectional illustration of a first heat exchange device according to the invention, which is driven by an asynchronous motor,

Fig. 2

the side view of the hollow body of a heat exchange device according to the invention,

Fig. 3

2 shows the schematic sectional illustration of a second heat exchange device according to the invention with a fan wheel,

Fig. 4

the schematic sectional view of a third heat exchange device according to the invention with an internal pump wheel and

Fig. 5

the schematic sectional view of a fourth heat exchange device according to the invention with one-sided supply and discharge of the medium flowing through the hollow body.

For the same or similar in the figures shown Components are given the same reference numbers below used.

1 shows a cylindrical hollow body 10, which has an inlet nozzle 12 and an outlet nozzle 14 contains. The inlet connector 12 is rotatable via a bearing 16 mounted on a fixed tubular inlet channel 18 and by a seal 20 opposite the inlet channel 18 sealed. The outlet connector 14 is via a bearing 22 rotatable on a fixed tubular outlet channel 24 stored and by a seal 26 opposite Outlet channel 24 sealed. So that the hollow body is 10 um the central axis 28 rotatably mounted. In the inlet channel 18 a fixed axial inlet opening 30 formed by the cooling liquid can enter the hollow body 10. in the Outlet channel 24 is a fixed axial outlet opening 32 formed by the cooling liquid from the hollow body 10 can leak.

The hollow body 10 is driven by an asynchronous motor 34 driven. For this purpose, on the exit side of the Hollow body 10 concentric with the hollow body 10 Aligned short-circuit cage 36, which forms the rotor 38 of the asynchronous motor 34 takes. An area of the hollow body 10 serves as short-circuit ring 40. Another short-circuit ring 42 is formed on the short-circuit cage 36. The hollow body 10 with the short-circuit cage 36 and the further short-circuit ring 42 consist of a component made of cast aluminum. The stator 44 of the Asynchronous motor 34 is in a housing 46 made of cast aluminum used. The housing 46 is fixed to the outlet channel 24 connected, which is also made of heat-conducting aluminum consists. Through this training, the components of the Asynchronous motor in good thermal contact with the through the Hollow body 10 flowing liquid and are by the Liquid well chilled. The bearing of the asynchronous motor 34 is taken over by the bearing 24 of the hollow body 10.

The asynchronous motor 34 is with a not shown Control unit connected, which allows the asynchronous motor 34th to run at variable speed. In the fields of Entry opening 30 and exit opening 32 are not temperature sensors for detecting the Inlet temperature and the outlet temperature of the by the Hollow body 10 flowing liquid arranged. Furthermore there is a temperature sensor, not shown in the Area of the peripheral surface of the hollow body which the Hollow body 10 surrounding ambient air detected. The signals of the temperature sensors are detected by the control device and used to control the speed of the hollow body 10.

The outer surface of the hollow body 10 is an air flow exposed. It is the ambient air through which cools the liquid flowing through the hollow body becomes. The cooling effect can be determined by the dimensions, in particular the wall thickness of the hollow body 10 and its Thermal conductivity properties are influenced. Because of the high possible peripheral speed of the rotating hollow body 10 finds an intimate heat exchange on the outside with the Ambient air instead. The heat exchange depends crucially on the size of the outer surface of the cooling air exposed Hollow body 10 from. Therefore, on the outer peripheral surface of the Hollow body 10 a plurality of elevations 48 and in between lying depressions 50 provided with the hollow body 10th are in good heat-conducting contact and preferably in the Hollow body 10 are integrated.

As is apparent from Fig. 2, the elevations 48 are oblique to the axis of rotation 28 arranged blades, which in addition to increasing the cooling effect, the function the promotion of cooling air.

3 shows a hollow body 10 through which a only undivided stationary tubular component (tube 52) extends at one end of an axial Entry opening 30 and at the other end there is an axial Exit opening 32 is located. The tube 52 contains inside of the hollow body 10 at its end facing the entry side Passages 54 that prevent coolant from exiting tube 52 allow in the hollow body 10. The tube 52 contains Inside of the hollow body 10 on its exit side facing end passages 56, which prevent the entry of the Allow coolant from the hollow body 10 into the tube 52. This is illustrated by arrows. To one Liquid flow through the middle, between the Passages 54, 56 lying section of the tube 10 to can avoid this section by a not shown Barrier closed or restricted by a restriction his. The storage and sealing of the hollow body 10 also takes place here (as shown in Fig. 1) by two bearings 16 and 22 and two seals 20 and 22. By using only one continuous tube 10 results in stable storage and reliable seal.

In order for the heat exchange between the hollow body wall and the flowing fluid to increase, it is appropriate involved surface inside the hollow body 10 to enlarge. For this purpose are on the inner wall of the Hollow body 10 a plurality of elevations 58 and in between lying recesses 60 provided with the hollow body in good thermal contact and preferably in the Hollow body 10 are integrated.

It is also of particular advantage here that the elevations 58 as to form blades arranged at an angle to the axis of rotation 28, so they have the function of pumping the liquid in part or can take over entirely.

At the outlet 14 of the hollow body 10 is a non-rotatably V-belt pulley 62 mounted, which is the rotary drive of the Hollow body 10 is used. The bearing of the V-belt pulley 62 is taken over by the bearing 22 of the hollow body 10. As Drive means also replace the V-belt pulley 62 other elements into consideration, such as B. a gear, a Flat belt pulley, a toothed belt wheel, a chain wheel and like.

At the inlet connector 12 of the hollow body 10 is a non-rotatable Fan wheel 64 mounted, which is with the hollow body 10th rotates and has the task of an air flow over the To blow the surface of the hollow body 10 and the hollow body 10 to cool. As a result, a separately driven blower or fan wheel unnecessary. The bearing of the fan wheel 64 is taken over by the bearing 20 of the hollow body 10.

In the flow direction in front of the fan wheel 64 and behind the Fan wheel 64 is a fixed, not rotating Guide housing 66, 68 indicated, which the leadership of Serve air flow. In many use cases it is only one guide housing 66 in front of the fan wheel 64 is sufficient or to provide a guide housing 68 behind the fan wheel 64.

In Fig. 4, a hollow body 10 is shown, on the cylindrical inside in a central area co-rotating impeller 70 is mounted. The impeller 70 can optionally in one piece with the hollow body 10 in one Injection molding process. The storage of the The impeller 70 is supported by the bearings 16, 22 of the hollow body 10 with taken over. The impeller 70 has the task of To promote liquid through the hollow body 10. This will a separate liquid pump is unnecessary.

In the direction of flow in front of the impeller 70 and behind the The impeller 70 is in the hollow body 10 each with the tube 10 connected fixed, non-rotating stator 72, 74 indicated which serve to guide the flow of liquid. In many applications, it is sufficient just one Stator 72 in front of the impeller 70 or a stator 74 behind the To provide impeller 70. The use of idlers 72, 74 may require the hollow body for assembly reasons to train in several parts.

5 shows a hollow body 80 which only opens on one side a concentric to the axis of rotation 81 82 has. Inside the socket 82 are two fixed, pipes 84, 86 not rotating with the hollow body 82 arranged concentrically. Through the inner of the two pipes 84 the coolant is supplied into the hollow body 82 (Entrance opening 85). The coolant is drained through the between inner tube 84 and outer tube 86 trained drain ring channel 87. This is through Arrows made clear. The connecting piece 82 is supported by a bearing 88 the outer tube 86 and a seal 90th sealed against the outer tube 86. Through this Coaxial, one-sided liquid supply and discharge can be bearings and seals are saved.

Radial overflow channels 92 are contained in the inner tube 84, which has a liquid passage between the inlet and the Allow expiration. Because of different Flow velocities in the inlet and outlet flow Part of the liquid from the inlet directly through the Overflow channels 92 in the drain ring channel 87 and not in the Interior of the hollow body 80. Furthermore, the ends of the outer tube 86 expanded conically, so that Return line acts as an injector and thus acts as one Suction jet pump works. This has the advantage of being in the area the bearing and sealing point with a reduced diameter constant volume flow in the outer cooling circuit possible becomes.

5 turned upward outer region of the Hollow body 80 is a filling opening 94 through a plug 96 is closed. The filling opening 94 serves filling and emptying the hollow body 80 and the whole Cooling system with coolant.

According to another design feature shown in FIG. 5 there is an elastic membrane 98 inside the hollow body 80 arranged that a part of the hollow body 80th enclosed volume from the other part of the hollow body separates and is not flowed through by the coolant. The elastic membrane 98 is shown schematically in FIG indicated spring 100 biased and thus leaves Volume changes in the liquid, for example can occur due to different temperatures. As an alternative to the spring 100 or in addition to the spring 100, the part separated by the membrane 98 also with a gas filling be filled.

Even if the invention is based only on a few Exemplary embodiments have been described, open up for the expert in the light of the above description and the Drawing many different alternatives, modifications and variants which fall under the present invention. So can, for example, many of the shown in the figures Features can be optionally combined with each other even if this is is not shown in detail.

Claims (22)

Device for heat exchange between a first fluid medium, preferably a liquid, and a second fluid medium, preferably a gas, with a hollow body (10, 80) through which one of the two media flows and the outside of which is exposed to the other of the two media, characterized in that the hollow body (10, 80) rotates about an axis. Device according to claim 1, characterized in that the hollow body (10, 80) has an axial inlet opening (30, 85) and an axial outlet opening (32, 87) for the medium flowing through. Apparatus according to claim 2, characterized in that the inlet opening (30, 85) and / or the outlet opening (32, 87) is formed in a fixed inlet channel (18, 84) or in a fixed outlet channel (24, 86) and that the hollow body (10, 80) is rotatably supported on the inlet channel (18, 84) and / or on the outlet channel (24) via at least one bearing (16, 22, 88) and possibly with seals (20, 26, 90) the inlet channel (18, 84) and / or the outlet channel (24) is sealed. Device according to one of the preceding claims, characterized in that a tubular component (52) extends axially through the hollow body (10) with an inlet opening (30) and outlet opening (32) lying outside the hollow body (10) and that the tubular component (52 ) in its area within the hollow body (10) has passages (54, 56) through which the medium flowing through the tubular component (52) can enter the hollow body (10) and exit it again. Device according to one of the preceding claims, characterized in that the liquid flowing through the hollow body (80) is supplied and removed coaxially from one side. Apparatus according to claim 5, characterized in that at least one overflow opening (92) is provided in a channel section separating the feed and the discharge, which enables a direct passage of a partial flow of the medium from the inlet opening (85) to the outlet opening (87). Apparatus according to claim 6, characterized in that at least a portion of the return line (86) is designed as an injector. Device according to one of the preceding claims, characterized in that a closable filling opening (94) is provided in an axially outer region of the hollow body (10, 80). Device according to one of the preceding claims, characterized in that an elastic membrane (98) is arranged in the interior of the hollow body (10, 80), which separates part of the volume enclosed by the hollow body (10, 80) from the medium flowing through and the is optionally biased. Device according to one of the preceding claims, characterized in that at least one pump wheel (70) rotating with the hollow body (10, 80) is fastened within the hollow body (10, 80). Device according to one of the preceding claims, characterized in that at least one stationary guide wheel (72, 74) or guide housing (66, 68) is provided inside the hollow body (10, 80) and / or outside the hollow body (10, 80). Device according to one of the preceding claims, characterized in that elevations (48, 58) and depressions (50, 60) are provided on an outer surface and / or an inner surface of the hollow body (10, 80). Device according to claim 12, characterized in that the elevations (48, 58) and depressions (50, 60) form blades arranged obliquely to the axis of rotation (28). Device according to one of the preceding claims, characterized in that a fan wheel (64) is connected to the hollow body (10, 80). Device according to claim 14, characterized in that the hollow body (10, 80) and the fan wheel (64) have at least one common bearing (16). Device according to one of the preceding claims, characterized in that drive means (34, 62) for introducing a torque are provided on the hollow body (10, 80). Device according to one of the preceding claims, characterized in that the hollow body (10, 80) is connected to the rotor (38) of an asynchronous motor (34). Apparatus according to claim 17, characterized in that the hollow body (10, 80) serves simultaneously as a short-circuit ring (40) of the asynchronous motor (34) and that, if necessary, on the hollow body (10, 80) as a short-circuit cage (36) for the asynchronous motor (34 ) serving approach is molded. Apparatus according to claim 17 or 18, characterized in that the stator (44) of the asynchronous motor (34) is inserted into a housing (46) made of a good heat-conducting material which is in good heat-conductive contact with the liquid medium. Device according to one of claims 16 to 19, characterized in that the mounting of the drive means (62) or the asynchronous motor (34) is carried out by at least one bearing (22) of the hollow body (10, 80). Device according to one of the preceding claims, characterized in that the hollow body (10, 80), optionally with its pump wheel (70), fan wheel (64) or with its elevations (48, 58) and depressions (50, 60), in particular its paddle wheels and possibly with the drive means (62) as well as with the short-circuit cage (36) and the short-circuit ring (42) of an electric motor (34) are essentially formed in one piece. Device according to one of the preceding claims, characterized in that the temperature of the inlet flow and / or the outlet flow of at least one of the media is detected and that a control unit controls the speed of rotation of the hollow body (10, 80) depending on the temperature measurement values.

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