WO2008034682A1

WO2008034682A1 - Assembly for cooling a liquid-cooled electrical machine with corrosion protection achieved by means of high-temperature zinc plating

Info

Publication number: WO2008034682A1
Application number: PCT/EP2007/058700
Authority: WO
Inventors: Christian Markert; Markus Oestreich
Original assignee: Siemens Aktiengesellschaft
Priority date: 2006-09-22
Filing date: 2007-08-22
Publication date: 2008-03-27
Also published as: DE102006044785A1; WO2008034682A8

Abstract

The invention relates to an assembly for cooling a liquid-cooled electrical machine using a cooling system. Said system has a cooling base body and a cooling jacket body and a cooling structure is situated between the cooling base body and the cooling jacket body. The cooling structure has a corrosion-resistant surface coating.

Description

description

Arrangement for cooling a liquid-cooled electric machine with corrosion protection by high-temperature tines

The invention relates to an arrangement for cooling a liquid-cooled electric machine with a cooling system, wherein the cooling system has a cooling base body and a cooling jacket body and wherein a cooling structure is arranged between the cooling base body and the cooling jacket body.

Cooling systems are used to protect components from thermal overload by dissipating the excess heat. The cooling system includes, for example, a liquid ^¬ cooling, wherein the heat-dissipating coolant is, for example, water. The resulting heat is absorbed by the cooling medium ^¬ and discharged for example via a Wärmetau ^¬ shear or heat exchanger or radiator, for example to the ambient air. The cooling device can also have, for example, a pump for a pump-controlled forced circulation cooling.

Cooling systems for liquid-cooled electrical machines are made, for example, of iron or steel. By using, for example, water as a coolant, the cooling system is exposed to corrosion, whereby damage to the destruction of the component, ie the cooling system, takes place. The corrosion product, which is made of iron or steel together with water and oxygen, is called rust. A component, for example, as long as possible the cooling system, it is necessary for reasons of host ^{¬-effectiveness} and environmental protection in terms of ^¬ to gangs of natural resources, protect the component by coating against corrosion and rust.

Previous cooling systems or heat sinks of electric motors, for example, by a cooling medium, such as acted upon, wherein the cooling medium corresponding inhibi ^¬ tors, ie corrosion-inhibiting substances are added. Oxygen corrosion in closed cooling systems is limited by the successive consumption of oxygen. The disadvantage here is that such inhibitors for Kühlsyste ^¬ me, which are operated for example with well or seawater, are not suitable for environmental reasons.

Object of the present invention is to provide a cooling system for a liquid-cooled electric machine bereitzustel ^¬ len having sufficient corrosion protection, and wherein the anticorrosive is as simple as possible to manufacture.

This object is solved by the features of patent claim 1. Advantageous developments can be found in the dependent claims.

By arranging a cooling system overheating of the electrical machine during operation is avoided. A Überhit ^¬ tion is not desirable because this burdened the components and their life shortened. This leads to additional costs for the repair or new acquisition of the components.

According to the invention, the arrangement for cooling a liquid-cooled electric machine includes a cooling system, wherein the cooling system has a cooling base body and a cooling jacket body. Between cooling body and cooling jacket body, a cooling structure is arranged. The cooling structure has a corrosion-resistant surface layer.

When using the cooling system for a rotary machine of the cooling base body is formed for example as a cylindrical hollow body, wherein on the outer surface of the hollow cylinder, the cooling structure is arranged. On or on the cooling structure of the cooling jacket body is arranged. The cooling system is arranged on the stator of the electrical machine, ie the cooling system encloses the stator of the electrical machine. see machine, the electric machine is preferably designed as an internal rotor machine. The cooling system is thus designed as a surface cooling, wherein the stator is flowed around by the coolant.

The entire cooling system is also hollow cylindrical ^{ausgebil ¬} det. The cooling system, which is designed as a cooling jacket system, is applied as a whole by shrinking onto the stator. The cooling jacket system is heated, causing it to expand and, with appropriate expansion, pushed onto the stator. After cooling, the cooling system is firmly attached to the stator.

The cooling structure preferably has a helical groove or the cooling structure itself is designed as a helical groove. The

Spiral groove is helically or radially encircling around the outer surface of the cooling base body, which is formed at ^{¬ play, for} example, as a hollow cylinder on the cooling body, where ^¬ in the helical groove in the direction of the cooling jacket body is open. Cooling base body and cooling structure can be formed in one or two parts. With a one-piece design of the cooling base body and the cooling structure, the helical groove can be produced, for example, by mechanical processing, for example by turning or milling. The cooling spiral groove could also be produced by forming the cooling base body. In the case of a two-part design, a helical groove can be formed, for example, by a circumferential web which is welded to the cooling main body. In the interstices of the individual web sections, a groove inevitably arises.

The radially ausgebil ^¬ an end in the circumferential direction of the heat sink body Kühlwendelnut can also be designed such that the helical groove extends in the axial direction (with respect to the rotary shaft of the electric machine). The cooling coil could, for example, be arranged meandering around the cooling base body. Also, the cooling coil may have different slopes and / or different axial distances. Is beispielswei ^¬ se a high cooling demand, the axial distance between the individual Wendelnutabschnitten is formed small, that the individual groove portions are located axially close to each other.

Advantageously, the corrosion-resistant surface ^¬ layer is formed as a zinc layer by means of high-temperature galvanizing (HTV).

High Temperature Galvanizing (HTV) is a special form of hot dip galvanizing. Among hot-dip galvanizing is meant the over ^¬ pull of steel parts with a massive, metallic zinc plating by immersing the pretreated steel parts in egg ne melt of liquid zinc. The galvanizing itself takes place in a zinc bath whose operating temperature is between 440 ⁰ C and 460 ⁰ C. Since the melting temperature of zinc at 419 ° C, this value is generally suffi ^¬ accordingly.

The durability distinguishes the hot-dip galvanizing from other corrosion protection methods. Even under extreme conditions, hot-dip galvanizing protects the steel for decades. The reason for the longevity of a hot-dip galvanizing is the inseparable connection that zinc and steel undergo. During hot dip galvanizing, a metallurgical reaction takes place in which steel and zinc form common iron-zinc alloy layers, over which, as a rule, a pure zinc coating is laid. The layer thickness is usually between 50 .mu.m and 150 .mu.m. The alloy makes this corrosion protection unrivaled hard, abrasion-resistant and resistant and therefore withstands even heavy mechanical loads effortlessly.

High-temperature galvanizing offers decisive advantages over conventional galvanizing. It is a dip-galvanizing process in which the special properties of the alloy phases zinc (Zn) and iron (Fe) at temperatures of 530 ⁰ C to 620 ⁰ C are exploited. By the high temperatures changes the structure of the alloy layers. It comes to a homogeneous layer growth. The resulting surface is characterized by a high micro-hardness. Further, a particularly thin and uniform alloy layer is provided ^¬ guaranteed by the high temperatures.

The well-known quality features of hot dip galvanizing such as longevity, catholic self-healing effect and price-worthiness are also given to HTV.

As already described, the cooling system has a hard to access internal cooling structure with complex geometry. According to the specification of the coolant, namely water, results in a high corrosive stress for the cooling system.

The cooling system is preferably a mechanically closed and thus liquid-tight welded construction made of steel, in particular St52, with a complex and difficult to access, ie internal, cooling structure. The cooling system is initially manufactured with cooling body, cooling structure and cooling jacket body. Subsequently, the entire cooling system is immersed in a high-temperature zinc bath. Since the cooling system, in particular the cooling jacket body, has an inlet and a drain for the coolant, this inlet and outlet can simultaneously serve as inlet and outlet for the liquid zinc. The liquid zinc which has a very low viscosity ^¬ passes through the inlet into the cooling structure, a, coated, the cooling structure and then passes out through the outlet from the cooling system.

The cooling system may also consist of two parts, wherein the cooling system, for example by an axial section (in loading train to the rotary shaft of the electric motor) in two parts ge ^¬ is divided. The advantage is that a coating of the cooling structure in the zinc bath is easier, since the cooling coil ^¬ nut is more easily accessible for the coating material. However, a disadvantage is that the parts must be assembled later at a cooling ^¬ system, for example by welding, thereby galvanizing but may be damaged.

Due to the high temperature galvanizing (HTV), it is possible to coat the complex inner contour continuously and due to the low viscosity of the coating material down to the smallest cavities. In conventional hot-dip galvanizing, the melt would solidify early in the passage through the long Kühlwendelnut and cause clogging of these grooves.

Surface refinement with a zinc coating ensures temporary corrosion protection. This results in an extended life of the cooling system at a ^¬ set in a closed cooling circuit.

The advantage of the HTV lies in the short process time and the low cost of the process. The principal advantage of galvanizing is the so-called self-healing process of the surface layer. Any damage (defects) of the surface layer would close itself within certain limits due to the potential differences (zinc less noble than steel).

Advantageously, the coolant is water, as in ^¬ example cold city water or filtered well, lake or river fresh water. The coolant can also be any other coolant.

Preferably, the cooling system for flow systems is appro ^¬ net. Flow systems are characterized by the fact that not only pure or distilled water but also well, lake or river water can be used as the coolant, ie water, which usually contains dirt particles. The coolant is directed through an inlet into the cooling system ^¬ into it, then flows through the Kühlwendelnut and absorbs the heat loss of the electric machine and then exits from a drain from the Kühlsys ^¬ tem. The cooling water releases the heat via a Wärmetau ^¬ shear or radiator to the ambient air. The now cooled water again passes through the cooling system, for example, a pump provides for water circulation.

The arrangement for cooling the liquid-cooled electric motor may also have a plurality of separate cooling systems, for example when the electric motor has a large axial length. The plurality of cooling systems are then arranged side by side in axial length and connected to each other, wherein the cooling systems can be connected in parallel and / or in series ^¬ Kings.

In a further embodiment, the cooling system is simultaneously formed as a housing for the electric machine. A housing protects the electric machine before Umwelteinflüs ^¬ sen, such as dirt. As already described, the cooling system encloses the stator of the electric machine, wherein the electric machine is preferably designed as an internal rotor machine. In an advantageous ^{Ausgestal ¬} tion, the cooling system is now formed in its axial extent, that it is designed to be longer than the stator and also, if present, winding heads of the stator over ^¬ covers. Thus, the winding heads are simultaneously protected and cooled by the cooling system. An additional housing ^¬ component is therefore not necessary, which material is ^¬ saves and the production costs are reduced.

The electric machine is preferably designed as a rotary permanent-magnet synchronous motor or servo-synchronous motor, wherein the synchronous motor can be designed as an internal rotor or external rotor machine.

The cooling system of the water-cooled electric machine is designed to be an operation of the electric machine or the electric motor can be operated in a flow-through system with protection against corrosion.

In the following description, further features and details of the invention in conjunction with the accompanying drawings will be explained in more detail by means of exemplary embodiments. In this case, features and relationships described in individual variants can in principle be applied to all exemplary embodiments. In the drawings show:

1 shows a perspective view of an inventive ^¬ Shen arrangement for cooling an electric machine;

2 shows a sectional view of the arrangement according to FIG. 1; 3 shows a first embodiment of a cooling coil ^¬ nut; and

4 shows a second embodiment of a Kühlwen ^¬ delnut.

1 shows a perspective view of a cooling system 1 for cooling an electric machine, not shown. The cooling system 1 has the cooling base body 2 and the cooling jacket body 4. Between cooling base body 2 and cooling jacket body 4, a cooling structure 3 is arranged, which is surface-coated corrosion-resistant.

According to FIG 1, the cooling system 1 is provided for a rotary machine, not shown. The cooling base body 2 is formed as a cylindrical hollow body, wherein on the outer surface 2 a of the hollow cylindrical cooling base 2, the cooling structure 3 is arranged. On or on the cooling structure 3, the cooling jacket body 4 is arranged. The cooling system 1 is arranged on a stator (not shown) of an electric machine (not shown), ie the cooling system 1 encloses the stator of the electric machine. The complete cooling system 1 is also formed as a hollow cylinder. The cooling structure 3 is formed as Kühlwendelnut 3a. The helical groove 3a is arranged on the cooling base body 2 in a helical or radially encircling manner around the outer surface 2a of the cooling base body 2, the helical groove 3a being open in the direction of the cooling jacket body 4. Cooling body 2 and cooling structure 3 are formed in one piece. The cooling structure 3 is made by me ^¬ chanical processing, for example by turning or frae ^¬ sen. The cooling structure 3 or the cooling coil 3a has a corrosion-resistant zinc layer, which is formed by means of high-temperature galvanizing (HTV).

The cooling system 1, in particular the cooling jacket body 4, also has an inlet 5a and a drain 5b for a coolant. Of course, the inlet 5a can also serve as the outlet 5b and the outlet 5b as the inlet 5a. Furthermore, inlet and outlet 5a, 5b can simultaneously serve as inlet and outlet for the high-temperature galvanizing, ie for the liquid zinc. The liquid zinc which has a very low viscosity ^¬ occurs, for example, through the inlet 5a in the cooling spiral groove 3a, a coated them, then comes out through the outlet 5b of the cooling system. 1

2 shows a sectional view of the arrangement according to FIG. 1. The representation according to FIG. 2 shows an axial section through the cooling system 1 parallel to a not shown

Rotary shaft of an electric machine, not shown. FIG. 2 shows that cooling base body 2 and cooling structure 3, which is designed as a cooling spiral groove 3 a, are formed in one piece. Above the cooling coil groove 3a, the cooling jacket body, which is designed, for example, as a simple sheet metal, is arranged on ^¬ and thus closes off the cooling system 1 to the outside. The cooling system 1 is shrunk onto the indicated stator 6 of an electric motor, not shown. The electric drive is designed for example as a permanent-magnet synchronous motor or servo-synchronous motor.

FIG 3 and FIG 4 show exemplary embodiments of a cooling ^¬ structure 3. FIG 3 shows a radially encircling Kühlwendelnut 3a, as shown in FIG. The radially in the circumferential direction of the heat sink body 2 formed cooling coil ^¬ groove 3a shown in FIG 3 can also be designed such that the helical groove 3a extending in the axial direction with respect to the adequacy pointed rotating shaft 7 of an electrical machine not shown in detail (FIG 4) , The cooling coil 3a according to FIG. 4 is arranged in a meander shape around the cooling base body 2. Furthermore, FIG. 3 and FIG. 4 show an indicated rotary shaft 7 of an electric motor and also indicated inlet and outlet 5a, 5b for the coolant.

Claims

claims

1. Arrangement for cooling a liquid-cooled electric machine with a cooling system (1), wherein the cooling system (1) has a cooling base body (2) and a cooling jacket body (4) and wherein between cooling base body (2) and cooling jacket body (4) has a cooling structure (3 ) is arranged, ^{¬ characterized in} that the cooling ^¬ structure (3) has a corrosion resistant surface layer.

2. Arrangement for cooling according to claim 1, characterized in that the cooling structure (3) for ^{¬ at} least one Kühlwendelnut (3a).

3. Arrangement for cooling according to claim 1 or 2, characterized in that the corrosi ^¬ onsbeständige surface layer is a zinc layer, wherein the zinc layer by high temperature galvanizing (HTV) is formed.

4. Arrangement for cooling according to one of claims 1 to 3, characterized in that the cooling ^¬ system (1) is a liquid-tight welded construction.

5. Arrangement for cooling according to one of claims 1 to 4, d a d u r c h e c e n e c e s in that the cooling jacket body (4) has at least one inlet (5a) and a drain (5b) for a coolant.

6. Arrangement for the cooling according to one of claims 1 to 5, d a d u c h e c e n e c i n e s in that the cooling system (1) has water as a coolant.

7. Arrangement for cooling according to one of claims 1 to 6, characterized in that the cooling system (1) is simultaneously formed as a housing for the electric machine.

8. Arrangement for cooling according to one of claims 1 to 7, characterized in that the e-lektrische machine is designed as a rotary permanent-magnet syn ^¬ chronmotor.