Cooling pipe assembly for linear motor

Abstract

The invention relates to a cooler (1) for a linear motor (19), to a primary part (9) for a linear motor (19) having such a cooler (1), and to a linear motor (19) having such a primary part (9). In order to achieve more uniform cooling of the primary part, the cooler (1) comprises a cooling channel (14) for the passage of a liquid cooling medium, wherein the cooling channel (14) is divided into a feed portion (3) having an inlet opening (6) for the introduction of the cooling medium into the feed portion (3) and a return portion (4) having an outlet opening (7) for the discharge of the cooling medium from the return portion (4), wherein the feed portion (3) extends helically from the outside to the inside in the flow direction of the cooling medium and the return portion (4) extends helically from the inside to the outside in the flow direction of the cooling medium in such a way that pipe portions of the return portion (4) are situated directly adjacently between two pipe portions of the feed portion (3).

Description

[0001] COOLING PIPE ARRANGEMENT FOR LINEAR MOTOR

[0002] The invention relates to a cooler for a linear motor, a primary part for a linear motor with such a cooler and a linear motor with such a primary part.

[0003] A linear motor comprises at least one primary part and at least one secondary part, which is separated from the primary part by an air gap. The primary part has a multi-phase, often three-phase, winding that generates a magnetic field. This exerts a force component across the air gap on the secondary part to enable translational movement. The secondary part often comprises permanent magnets, whose magnetic field interacts with the magnetic field of the primary part to generate said force component. Instead of permanent magnets, the secondary part can also carry a coil winding that serves to generate the corresponding magnetic field.In addition, linear motors are known in which the primary part is equipped with both a multi-phase coil winding and permanent magnets, while the secondary part is free of magnetic field generating components, but is simply manufactured as a toothed structure made of ferromagnetic material.

[0004] Linear motors are not free from ohmic conduction losses and magnetic iron losses, which lead to motor overheating. The coils of the primary section, in particular, are the dominant heat source. To prevent excessive heating of the linear motor and / or adjacent components, the heat generated in the linear motor, and especially in the primary section, must be dissipated. The more effective the motor's heat dissipation is, the higher the achievable power density.

[0005] For cooling the primary part of a linear motor, coolers with cooling channels for the passage of a liquid coolant are known. The cooling medium can be water or oil, for example. The cooling channels are often integrated directly into a laminated core of the primary part, which also supports the primary coils. Alternatively, the cooler with these channels can be designed as a separate component that is thermally coupled to the laminated core of the primary part.

[0006] To avoid hot spots, the aim is always to achieve the most homogeneous temperature distribution possible in the primary part. To this end, EP 2 720 351 B1 discloses a device for cooling a laminated core of a dynamoelectric machine by means of a first cooling coil and at least one further cooling coil. The first and further cooling coils have meander-shaped sections connected to one another via spacer sections for cooling individual, non-adjacent regions of the laminated core. The spacer sections of the first cooling coil are provided for bridging the regions for whose cooling the meander-shaped section of the further cooling coil is provided, and the spacer sections of the further cooling coil are provided for bridging the regions for which cooling is provided by the meander-shaped sections of the first cooling coil.

[0007] CN 102158043 B shows a liquid-cooled linear motor with a reduced temperature difference between a front and a rear end of its primary part. A cooling tube consists of a water inlet tube and a water outlet tube, wherein the water inlet tube consists of a plurality of parallel cooling sections and a plurality of curved connecting sections. Any two adjacent cooling sections are connected to each other by the connecting sections. The water outlet tube consists of a plurality of parallel cooling sections and a plurality of curved connecting sections. Two adjacent cooling sections are connected to each other by the connecting sections. The cooling sections of the water inlet tube and the cooling sections of the water outlet tube are arranged alternately. At the rear end of the primary part of the motor, the water inlet tube and the water outlet tube are connected to each other to form a passage.A water outlet of the water outlet pipe and a water inlet of the water inlet pipe are arranged at the front end of the primary part of the engine.

[0008] The invention is based on the object of enabling even more uniform heat dissipation in a linear motor. This object is achieved by a cooler having the features of claims 1 or 2. Advantageous embodiments of the invention can be found in the dependent patent claims.

[0009] The cooler according to the invention comprises a cooling channel for the passage of a liquid cooling medium. This can be, for example, oil or water. The cooling medium can be introduced through an inlet opening into a flow section of the cooling channel and discharged through an outlet opening from a return section of the cooling channel. The discharged cooling medium can be cooled again via a heat exchanger, which can be part of a closed cooling circuit, and then fed back into the cooler through the inlet opening.

[0010] The cooling channel is thus divided into a supply section, which, viewed from the inlet opening, occupies approximately half the length of the cooling channel in the direction of flow, and a return section, which runs from the end of the supply section in the direction of flow to the outlet opening and thus comprises approximately the second half of the cooling channel. From the inlet to the outlet opening, the cooling medium is continuously heated by the losses generated by the linear motor. The supply section and return section can be sections of a single-piece cooling channel. However, they can also be designed as separate, interconnected channel sections.

[0011] The invention is based on the finding that a particularly homogeneous temperature distribution can be achieved by arranging the flow section in a spiral shape from the outside to the inside in the direction of flow of the cooling medium, and the return section in a spiral shape from the inside to the outside in the direction of flow of the cooling medium, such that pipe sections of the return section are arranged directly adjacent between two pipe sections of the flow section. The inlet and outlet openings for the cooling medium are located in the outer region of the spiral cooling channel.

[0012] The same inventive concept underlies a cooler in which the supply section runs spirally from the inside out in the direction of flow of the cooling medium, and the return section runs spirally from the outside in the direction of flow of the cooling medium, such that pipe sections of the return section are arranged directly adjacent between two pipe sections of the supply section. The inlet and outlet openings for the cooling medium are located in the inner region of the spiral cooling channel.

[0013] In both cases, the cooling channel layout is bifilar and spiral. The flow direction of the cooling medium is always opposite between two adjacent pipe sections. The spiral, bifilar layout of the cooling channels leads to excellent homogenization of the temperature distribution within the cooler. The averaged cooling medium temperature across two adjacent pipe sections is essentially the same, which cannot be achieved to the same extent with prior art coolers for linear motors.

[0014] In an advantageous embodiment of the invention, the cooling channel is embedded in an aluminum plate. A laminated core of the primary part can be mounted directly on the aluminum plate to ensure good heat transfer. However, an embodiment of the invention is also conceivable in which the cooling channel is integrated directly into the yoke of the laminated core, thus allowing the laminated core of the primary part itself to function as a cooler. Alternatively, a copper plate can also be used.

[0015] The inlet opening can be arranged directly next to the outlet opening so that the coolant connection between the linear motor and any heat exchanger provided can be designed to be particularly compact.

[0016] The cooler advantageously comprises thermal insulation on one mounting side of the cooler. This mounting side is, for example, a side facing away from the primary part of the linear motor, with which the linear motor including the cooler can be mounted on a production system or machine tool. The thermal insulation can be implemented in the form of individual insulation pads made of material with poor thermal conductivity. The insulation pads can create an air layer with excellent insulating properties between the mounting side of the cooler and adjacent components. If a cooler according to one of the previously described embodiments is mounted on the yoke back of a laminated core of a primary part that has teeth wound with coils, a linear motor with particularly homogeneous heat distribution can be realized.

[0017] The invention is explained in more detail below with reference to the exemplary embodiments illustrated in the figures. Functionally equivalent elements are provided with the same reference numerals, even if their specific design differs.

[0018] They show:

[0019] FIG 1 schematically shows a meandering cooling channel course according to the prior art,

[0020] FIG 2 is a three-dimensional representation of a cooling channel according to the scheme shown in FIG 1,

[0021] FIG 3 schematically shows a spiral and bif ilar cooling channel course according to an embodiment of the invention,

[0022] FIG 4 is a three-dimensional representation of a cooling channel according to the scheme shown in FIG 3,

[0023] FIG 5 shows a cooler in the form of an aluminum plate according to an embodiment of the invention,

[0024] FIG 6 a primary part I of a linear motor according to an embodiment of the invention,

[0025] FIG 7 shows a secondary part for a linear motor according to an embodiment of the invention and

[0026] FIG 8 is a schematic representation of a linear motor according to an embodiment of the invention.

[0027] FIGS. 1 and 2 show the meandering cooling channel of a cooler for linear motors, as is known from the prior art. The meandering cooling channel 14 can be designed either in the direction of movement of the linear motor or transversely thereto. The cooling channel 14 comprises an inlet opening 6 for a liquid cooling medium and an outlet opening 7 through which said cooling medium is discharged from the cooling channel 14 to be cooled again in a heat exchanger (not shown).

[0028] In FIG 1, pipe sections of the cooling channel are provided with numbers which indicate the order in which the cooling medium flows through the pipe sections. As the number increases, the temperature in the pipe sections increases due to the heat introduced, for example, by a primary part of a linear motor. Due to the meandering layout of the cooling channel 14, the temperature therefore increases continuously from right to left in FIG 1. This has the consequence that a cooler in which the illustrated cooling channel 14 is integrated heats up inhomogeneously. It will be significantly warmer in the left-hand area than in the right-hand area with reference to the illustration in FIG 1. If such a cooler is installed in an industrial plant, for example, this inhomogeneous heat distribution will also be transferred to it, which is undesirable in many applications.

[0029] The above statements apply analogously to the 3-dimensional representation in FIG 2, although here the left and right sides are reversed compared to FIG 1, since here the meandering cooling channel runs from left to right in the flow direction.

[0030] FIG. 3 schematically shows a spiral-shaped and bifilar cooling channel pattern according to one embodiment of the invention. FIG. 4 shows a three-dimensional representation of a cooling channel realized according to the scheme shown in FIG. 3.

[0031] Here, too, a liquid cooling medium enters the cooling channel 14 via an inlet opening 6 and is discharged from it again via an outlet opening 7. Similar to FIG. 1, in FIG. 3, the pipe sections of the cooling channel 14 are numbered consecutively in the flow direction of the cooling medium.

[0032] The cooling channel is divided into a supply section 3, which is fed with the cooling medium through the inlet opening 6, and a return section 4, which ends at the outlet opening 7. A transition point 21 can be defined, which is located approximately in the middle of the length of the entire cooling channel 14 and separates the supply section 3 from the return section 4. In this context, it is important to understand that the separation into supply and return sections is not necessarily associated with a two-part design of the cooling channel, but merely serves to conceptually separate the supply and return sections 3, 4. The supply and return sections 3, 4 can very well be elements of a cooling channel 14 in a one-piece form.

[0033] The cooling channel is bifilar and spiral-shaped. This means that pipe sections of the supply section 3 and immediately adjacent pipe sections of the return section 4 run in a spiral pattern from the outside to the inside. This results in the temperature of the cooling medium averaged over two adjacent pipe sections being significantly more homogeneous than in the meandering design shown in FIGS. 1 and 2.

[0034] The inlet opening 6 is located in the radially outermost region of the spiral-shaped cooling channel 14, and the outlet opening 7 is immediately adjacent to it, offset inward by one radial position. Of course, the radial positions of the inlet opening 6 and outlet opening 7, and thus the positions of the pipe sections of the flow section 3 and the return section 4, can also be swapped by this one radial position.

[0035] FIG 5 shows a cooler in the form of an aluminum plate 5 according to one embodiment of the invention. The illustrated aluminum plate 5 is intended for mounting on the yoke of a primary part of a linear motor in order to effectively dissipate heat from the motor.

[0036] Finally, FIG. 6 shows a primary part 9 of a linear motor according to an embodiment of the invention, with the aluminum plate 5 shown in FIG. 5, which is mounted on a yoke back 12 of a laminated core 10 constructed from bonded motor laminations in order to dissipate heat therefrom. A bifilar and spiral cooling channel 14 integrated into the aluminum plate is fed with a liquid coolant via a cooling water connection 15. Coils 11 concentrically enclose teeth of the laminated core 10 and form a 3-phase tooth-wound coil winding for generating the armature field. The coils 11 are supplied with power via a cable outlet 16. To improve heat conduction within the coils 5, a vacuum potting 13 is provided. The aluminum plate 5 is equipped with thermal insulation pads 8 on one mounting side. These reduce the heat input from the primary part or its cooler to adjacent components.

[0037] FIG. 7 shows a secondary part 20 for a linear motor according to an embodiment of the invention and FIG. 8 finally schematically shows such a linear motor 19.

[0038] The secondary part essentially consists of a base plate 17 which is equipped with permanent magnets 18.

[0039] List of reference symbols

[0040] cooler

[0041] linear motor

[0042] Preliminary section

[0043] Return section

[0044] aluminum plate

[0045] Inlet opening

[0046] Outlet opening

[0047] Thermal insulation pads

[0048] Primary part

[0049] Sheet metal package

[0050] Sink

[0051] yoke ridge

[0052] Vacuum casting

[0053] cooling channel

[0054] Cooling water connection

[0055] Cable outlet

[0056] Base plate

[0057] permanent magnet

[0058] linear motor

[0059] Secondary part

[0060] Transition point

Claims

Patent claims 1. Cooler (1) for a linear motor (2) with a cooling channel (14) for the passage of a liquid cooling medium, wherein the cooling channel (14) is divided into a supply section (3) with an inlet opening (6) for introducing the cooling medium into the supply section (3) and a return section (4) with an outlet opening (7) for discharging the cooling medium from the return section (4), characterized in that the supply section (3) runs spirally from the outside to the inside in the flow direction of the cooling medium and the return section (4) runs spirally from the inside to the outside in the flow direction of the cooling medium in such a way that pipe sections of the return section (4) are arranged directly adjacent between two pipe sections of the supply section (3).

2. Cooler (1) for a linear motor (2) with a cooling channel (14) for the passage of a liquid cooling medium, wherein the cooling channel (14) is divided into a supply section (3) with an inlet opening (6) for introducing the cooling medium into the supply section (3) and a return section (4) with an outlet opening (7) for discharging the cooling medium from the return section (4), characterized in that the supply section (3) runs spirally from the inside to the outside in the flow direction of the cooling medium and the return section (4) runs spirally from the outside to the inside in the flow direction of the cooling medium in such a way that pipe sections of the return section (4) are arranged directly adjacent between two pipe sections of the supply section (3).

3. Cooler (1) according to claim 1 or 2, wherein the cooling channel (14) is embedded in an aluminum plate (5).

4. Cooler (1) according to one of claims 1 to 3, wherein the inlet opening (6) is arranged directly next to the outlet opening (7).

5. Cooler (1) according to one of the preceding claims with a thermal insulation (8) on a mounting side of the cooler (1).

6. Primary part (9) with a laminated core (10) which has teeth wound with coils (11) and a yoke back (12) for forming a magnetic return path, wherein the yoke back (12) is mounted on a cooler (1) according to one of claims 1 to 5.

7. Linear motor (19) with a primary part (9) according to claim 6 and a secondary part

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