Cooling tube arrangement for linear motor

Abstract

The present invention relates to a cooler (1) for a linear motor (19), a primary component (9) of the linear motor having said cooler (1), and a linear motor (19) having said primary component (9). To achieve more uniform heat dissipation of the primary component, the cooler (1) includes a cooling channel (14) for conducting liquid cooling medium, wherein said cooling channel (14) is divided into: a supply section (3) having an inlet opening (6) to introduce said cooling medium into said supply section (3), and a return section (4) having an outlet opening (7) to discharge said cooling medium from said return section (4), wherein said supply section (3) extends spirally from the outside to the inside along the flow direction of said cooling medium, and said return section (4) extends spirally from the inside to the outside along the flow direction of said cooling medium, such that the pipe segments of said return section (4) are arranged adjacent to each other between the two pipe segments of said supply section (3).

Description

Technical Field

[0001] The present invention relates to a cooler for a linear motor, a primary component of a linear motor having said cooler, and a linear motor having said primary component. Background Technology

[0002] A linear motor includes at least one primary component and at least one secondary component separated from the primary component by an air gap. The primary component has multiphase (typically three-phase) windings that generate a magnetic field. This magnetic field applies a force component to the secondary component through the air gap, thereby achieving linear motion. The secondary component typically includes a permanent magnet whose magnetic field interacts with the magnetic field of the primary component to generate the aforementioned force component. Alternatively, the secondary component may carry coil windings for generating the corresponding magnetic field. Furthermore, linear motors are known in which the primary component is equipped with both multiphase coil windings and a permanent magnet, while the secondary component does not have a component for generating a magnetic field but is only composed of a toothed structure made of ferromagnetic material.

[0003] Linear motors suffer from ohmic conductivity losses and magnetic ferro losses, which cause the motor to heat up. The coils in the primary component, in particular, can be considered the dominant heat source. To avoid unacceptable overheating of the linear motor and / or adjacent components, the heat generated in the linear motor, especially in the primary component, must be dissipated. The more effective the motor's thermal design, the higher the power density the motor can achieve.

[0004] To dissipate heat from the primary components of a linear motor, it is known to use a cooler having cooling channels for conducting a liquid cooling medium. The cooling medium can be, for example, water or oil. In this case, the cooling channels are typically integrated directly into the lamination stack of the primary components, which also carries the primary coil. Alternatively, it is also known to manufacture the cooler with the channels as a separate component thermally coupled to the lamination stack of the primary components.

[0005] To avoid hot spots, efforts are made to achieve the most uniform temperature distribution possible in the primary components under all circumstances. To this end, EP 2 720 351 B1 discloses a device for cooling a lamination stack of a generator motor, which is implemented by a first cooling coil and at least one further cooling coil, wherein the first cooling coil and the further cooling coil have serpentine sections connected to each other by distance segments for cooling non-adjacent areas of the lamination stack, wherein the distance segments of the first cooling coil are used to span those areas to be cooled by the serpentine sections of the further cooling coil, and the distance segments of the further cooling coil are used to span those areas to be cooled by the serpentine sections of the first cooling coil.

[0006] CN 102158043 B discloses a liquid-cooled linear motor with reduced temperature difference between the front and rear ends of its primary component. A cooling pipe includes an inlet pipe and an outlet pipe, wherein the inlet pipe consists of multiple parallel cooling sections and multiple curved connecting sections. Adjacent cooling sections are connected to each other by connecting sections. The outlet pipe also includes multiple parallel cooling sections and multiple curved connecting sections. Adjacent cooling sections are connected to each other by connecting sections. The cooling sections of the inlet pipe and the outlet pipe are arranged alternately. At the rear end of the motor primary component, the inlet pipe and the outlet pipe are connected to each other to form a channel. The outlet of the outlet pipe and the inlet of the inlet pipe are located at the front end of the motor primary component. Summary of the Invention

[0007] The purpose of this invention is to achieve more uniform heat dissipation in a linear motor.

[0008] This objective is achieved by a cooler having the features of claim 1 or 2. Advantageous embodiments of the invention are derived from the dependent patent claims.

[0009] The cooler according to the invention includes a cooling channel for conducting a liquid cooling medium. The cooling medium may be, for example, oil or water. The cooling medium can enter the supply section of the cooling channel through an inlet opening and can be discharged from the return section of the cooling channel through an outlet opening. The discharged cooling medium can be cooled again by means of a heat exchanger that can be part of a closed cooling loop, and then supplied back to the cooler through the inlet opening.

[0010] Therefore, the cooling channel is divided into a supply section, which extends from the inlet opening and occupies approximately half the length of the cooling channel along the flow direction, and a return section, which extends from the end of the supply section along the flow direction to the outlet opening, and thus approximately comprises a second half of the cooling channel. From the inlet opening to the outlet opening, the cooling medium continuously heats up due to losses generated by the linear motor. The supply section and the return section can be segments of a single cooling channel. They can also be constructed as independent channel segments connected to each other.

[0011] The present invention recognizes that a particularly uniform temperature distribution can be generated by the following arrangement: the supply section extends spirally from the outside to the inside along the flow direction of the cooling medium, and the return section extends spirally from the inside to the outside along the flow direction of the cooling medium, such that the pipe segments of the return section are arranged adjacent to each other between the two pipe segments of the supply section. Here, the inlet and outlet openings for the cooling medium are located in the outer region of the spirally extending cooling channel.

[0012] The same inventive concept also applies to a cooler in which the supply section extends spirally from the inside to the outside along the flow direction of the cooling medium, and the return section extends spirally from the outside to the inside along the flow direction of the cooling medium, such that the pipe segments of the return section are arranged adjacent to each other between the two pipe segments of the supply section. Here, the inlet opening and outlet opening for the cooling medium are located in the inner region of the spirally extending cooling channel.

[0013] In both cases, the cooling channels are arranged in a double-strand, spiral pattern. For two adjacent pipe sections, the flow direction of the cooling medium is always opposite. The spiral double-strand arrangement of the cooling channels results in excellent homogenization of the temperature distribution inside the cooler. The average temperature of the cooling medium obtained for two adjacent pipe sections is essentially equal, which cannot be achieved in the same way in known coolers used for linear motors.

[0014] In an advantageous improvement of the invention, the cooling channel is embedded in an aluminum plate. The laminations of the primary component can be directly mounted on the aluminum plate to ensure good heat transfer. It is also conceivable that the cooling channel be directly integrated into the yoke of the laminations, thereby allowing the laminations of the primary component to act as a cooler themselves. Alternatively, a copper plate can be used.

[0015] The inlet opening can be directly adjacent to the outlet opening, allowing for a particularly compact design of the cooling water connection between the linear motor and any potential heat exchanger. Advantageously, the cooler includes a heat insulation element on its mounting side. This mounting side is, for example, the side opposite the primary components of the linear motor, through which the linear motor and cooler can be mounted on a production device or machine tool. The heat insulation element can take the form of a single heat-insulating gasket made of a material with low thermal conductivity. This heat-insulating gasket creates an air layer with excellent thermal insulation between the mounting side of the cooler and adjacent components. If the cooler according to any of the above embodiments is mounted on a yoke back having a lamination stack of primary components having teeth wound with coils and having a yoke back for forming a magnetic circuit, a linear motor with particularly uniform heat distribution can be realized. Attached Figure Description

[0016] The present invention will now be described in detail with reference to the embodiments shown in the accompanying drawings. Elements with the same function are denoted by the same reference numerals, even if their specific constructions differ.

[0017] The accompanying drawings show: Figure 1 schematically illustrates the serpentine cooling channel layout in the prior art; Figure 2 shows a three-dimensional representation of the cooling channel according to the scheme in Figure 1; Figure 3 schematically illustrates the direction of a spiral and double-stranded cooling channel according to an embodiment of the present invention; Figure 4 shows a three-dimensional representation of the cooling channel implemented according to the scheme in Figure 3; Figure 5 shows a cooler in the form of an aluminum plate according to an embodiment of the present invention; Figure 6 shows the primary components of a linear motor according to an embodiment of the present invention; Figure 7 illustrates a secondary component for a linear motor according to an embodiment of the present invention; and Figure 8 shows a schematic representation of a linear motor according to an embodiment of the present invention. Detailed Implementation

[0018] Figures 1 and 2 show the serpentine cooling channel layout for a cooler used in a linear motor, as known in the prior art. The serpentine cooling channel 14 can be implemented along the direction of motion of the linear motor or transverse to that direction.

[0019] The cooling channel 14 includes an inlet opening 6 for a liquid cooling medium and an outlet opening 7 for discharging the cooling medium from the cooling channel 14 so that it may be cooled again in a heat exchanger (not shown).

[0020] In Figure 1, the pipe segments of the cooling channel are numbered, indicating the order in which the cooling medium flows through each segment. As the number increases, the temperature in the pipe segment rises due to heat introduced, for example, by the primary components of a linear motor. Due to the serpentine layout of the cooling channel 14, the temperature rises continuously from right to left in Figure 1. Therefore, in a cooler integrating the cooling channel 14 shown, the temperature rise is uneven. Referring to Figure 1, the left-hand area will be significantly hotter than the right-hand area. If such a cooler is installed, for example, in an industrial installation, this uneven temperature distribution will also be transmitted to the installation, which is undesirable in many applications.

[0021] The above discussion also applies to the three-dimensional representation of Figure 2. However, compared to Figure 1, the representations on the left and right sides are interchanged here because the serpentine cooling channel extends from left to right along the flow direction.

[0022] Figure 3 schematically illustrates the spiral, double-stranded cooling channel configuration according to an embodiment of the present invention. Figure 4 shows a three-dimensional representation of the cooling channel implemented according to the scheme shown in Figure 3.

[0023] Here, the liquid cooling medium also enters the cooling channel 14 through the inlet opening 6 and is discharged from it through the outlet opening 7. Similar to Figure 1, the pipe sections of the cooling channel 14 shown in Figure 3 are also numbered according to the flow direction of the cooling medium.

[0024] The cooling channel is divided into a supply section 3, which supplies the cooling medium through an inlet opening 6, and a return section 4, which terminates at an outlet opening 7. A transition point 21 can be defined, located approximately midway along the length of the entire cooling channel 14, separating the supply section 3 from the return section 4. In this context, it is important to understand that dividing it into supply and return sections does not necessarily imply that the cooling channel is a two-piece configuration, but is merely a conceptual distinction between the supply and return sections 3 and 4. The supply and return sections 3 and 4 can be integral components of a single, monolithic cooling channel 14.

[0025] The cooling channel is arranged in a double-strand, spiral shape. That is, the pipe section of the supply section 3 and the adjacent pipe section of the return section 4 extend together from the outside to the inside in a spiral manner. As a result, compared with the serpentine implementation shown in Figures 1 and 2, the average temperature of the cooling medium on the two adjacent pipe sections is significantly more uniform.

[0026] The inlet opening 6 is located in the radially outermost region of the spiral-extended cooling channel 14, while the outlet opening 7 is adjacent to its inner side and offset radially inward. Of course, the radial positions of the inlet opening 6 and the outlet opening 7, and thus the pipe sections of the supply section 3 and the return section 4, can also be interchanged through this radial position.

[0027] Figure 5 shows a cooler constructed in the form of an aluminum plate 5 according to an embodiment of the present invention. The aluminum plate 5 shown is used to be mounted on the yoke of the primary component of a linear motor for effective heat dissipation.

[0028] Figure 6 finally shows the primary component 9 of a linear motor according to an embodiment of the present invention, which has an aluminum plate 5 as shown in Figure 5, which is mounted on the yoke 12 of a lamination stack 10 made of motor steel sheets sintered and bonded together for heat dissipation. A liquid cooling medium is supplied through a double-stranded, spiral cooling channel 14 integrated in the aluminum plate via a cooling water connector 15. A coil 11 concentrically surrounds the teeth of the lamination stack 10 and forms a three-phase toothed winding for generating an armature field. Power is supplied to the coil 11 through a cable outlet 16. A vacuum potting 13 is provided to improve the thermal conductivity inside the coil 5.

[0029] The aluminum plate 5 is equipped with a heat insulation element 8 on its mounting side. This reduces the heat input from the primary component and / or its cooler to adjacent components.

[0030] Figure 7 shows a secondary component 20 for a linear motor according to an embodiment of the present invention, and Figure 8 finally shows such a linear motor 19 in a schematic manner. The secondary component is mainly composed of a substrate 17 on which permanent magnets 18 are mounted.

[0031] Explanation of reference numerals in the attached figures 1. Cooler 2. Linear motor 3. Supply Section 4. Recirculation Section 5 Aluminum Plate 6. Entrance opening 7. Exit opening 8. Thermal insulation components 9. Primary Components 10-Laminated Sheet 11 coils 12. Yoke back 13 Vacuum potting 14 Cooling Channels 15 Cooling water connector 16 Cable outlet 17 substrate 18 permanent magnets 19 Linear Motors 20 secondary components 21 Transition Point

Claims

1. A cooler (1) for a linear electric machine (2) having a cooling channel (14) for conducting a liquid cooling medium, the cooling channel (14) being divided into a supply section (3) having an inlet opening (6) for introducing the cooling medium into the supply section (3) and a return section (4) having an outlet opening (7) for discharging the cooling medium from the return section (4), characterized in that: Along the flow direction of the cooling medium, the supply section (3) extends spirally from the outside to the inside, and along the flow direction of the cooling medium, the return section (4) extends spirally from the inside to the outside, so that the pipe section of the return section (4) is arranged adjacent to the two pipe sections of the supply section (3).

2. A cooler (1) for a linear electric machine (2) having a cooling channel (14) for conducting a liquid cooling medium, the cooling channel (14) being divided into a supply section (3) having an inlet opening (6) for introducing the cooling medium into the supply section (3) and a return section (4) having an outlet opening (7) for discharging the cooling medium from the return section (4), characterized in that: Along the flow direction of the cooling medium, the supply section (3) extends spirally from the inside to the outside, and along the flow direction of the cooling medium, the return section (4) extends spirally from the outside to the inside, so that the pipe section of the return section (4) is arranged adjacently between the 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 the aluminum plate (5).

4. The cooler (1) according to any one of claims 1 to 3, wherein The inlet opening (6) is directly adjacent to the outlet opening (7).

5. The cooler (1) according to any of the preceding claims, wherein a heat insulation element (8) is provided on the mounting side of the cooler (1).

6. A primary component (9) having a lamination stack (10) with teeth to which coils (11) are wound and yoke backs (12) for forming a magnetic circuit, wherein The yoke (12) is mounted on the cooler (1) according to any one of claims 1 to 5.

7. A linear motor (19) comprising a primary component (9) as claimed in claim 6 and a secondary component (20).

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