GB2030790A - Holding and mounting device for heat-dissipating components in rotating electrical machines - Google Patents

Abstract

The device is a slip ring end frame of a vehicle three-phase generator and mounts diodes (37) in groups on three heat sinks (9a, 9b, 9c). Each heat sink has at either end a lug (14a, 14b) having a through bore to receive a bolt (18), by which the heat sinks are secured on ribs (7) of a base plate (4) of the end frame, the ribs being distributed circumferentially round the inner periphery of a rim portion 5 of the plate so that the heat sinks follow in succession round the plate. Bus bar holders (16a, b, c and d) are also secured by the bolts (18) to provide, radially inwardly of the heat sinks, grooves (29a, b and c, Fig. 6, not shown) to support sections of the bus bars (11a, 11b) and diode leads (51, 52, 53). This arrangement provides a compact assembly but one in which the component parts are readily accessible. The heat sinks are cooled by air flow through plate apertures (10a, b, c). <IMAGE>

Description

SPECIFICATION Holding and mounting device for heat-dissipating components in rotating electrical machines The present invention relates to a holding and mounting device for inter alia heat-dissipating components in rotating electrical machines.

Such a device is exemplified by a slip-ring end frame for mounting of rectifier diodes and their heat sinks, and terminal connections in three-phase generators; the end frame serving to mount the diodes with their heat sink and terminal connections in a vibration free manner and to render them convenient to mount and repair, and also to ensure satisfactory dissipation of heat. Hereinafter, for convenience, the invention will be described with reference to a slip-ring end frame.

A "slip-ring end frame" has a plurality of mutually electrically insulated cooling arrangements which support the rectifier diodes and which, together with insulating holders for receiving bus bars, are distributed around the periphery of a base plate of the frame and are secured to the same location. The bus bars are staggered relative to one another in an axial direction and a radial direction and are inserted into engagement means in the holders.

The basic construction of a three-phase generator includes a three-phase stator winding acting as a normally fixed member, and a rotor on the shaft of which are mounted the magnetic poles and the excitation winding and, in most cases, two slip-rings. The rotor shaft is journalled in two bearings, one of which is provided by the slip-ring end frame since the brush-holder is disposed adjacent to this bearing and can be fixed in the same bearing spigot which also accommodates the roller bearing bore for the shaft.

Carbon brushes press against the two sliprings and thus transmit the excitation current, originating from the stator winding, to the rotating excitation winding. When the threephase generator is intended for motor vehicles or other mobile units, connection terminals are provided on the generator for the electrical connection of the latter to a regulator which adjusts the excitation current according to the power requirement placed on the three-phase generator.

Since the voltage of the electrical system of a motor vehicle or some other unit is usually and chiefly direct current owing to the battery provided, the three-phase alternating current generated in the stator winding of the generator has to be rectified, this usually being effected by means of rectifier diodes.

Six power diodes, and three excitation diodes separated therefrom for generating the excitation current, are provided. Alternatively, in the case of a very high current requirement, each of the six power diodes can be a parallel combination comprising a desired number of diodes which are then connected identically.

Since the semi-conductor diodes may be heated only up to specific temperatures, the heat due to energy losses has to be reliably dissipated, so that the diodes are normally fitted in so-called heat sinks. Larger threephase generators can be provided with a rectifier system which comprises three heat sinks and in which the diodes are combined in three groups of three, each group comprising a positive diode, a negative diode, and an excitation diode, and a heat sink being associated with each group. The heat sinks can be provided with cooling fins owing to the high currents which a three-phase generator of corresponding design can produce.

A need exists for a vibration-proof, exchangeable rectifier system which is associated with the slip-ring end frame and which is convenient to repair and mount and which ensures a high degree of operational reliability.

There is provided by the present invention a holding and mounting device for the mounting of rectifier diodes, their heat-sinks and terminal connections in a rotating electrical machine, wherein the device comprises a base plate, and a plurality of mutually electrically insulated heat-sinks having support extensions, for mounting the rectifier diodes, which support extensions, together with insulating holders for receiving bus bars are secured to location points distributed around the circumference of the base plate; the latter being provided with a central bearing bore for the rotor shaft.

The holding and mounting device in accordance with the invention has the advantage that a balanced cooling action with respect to the diodes is ensured even in the case of three-phase generators having a very high construction, and optimisation of the thermal conditions being ensured. Furthermore, it is advantageous that a balanced cooling action is ensured by the fact that the heat is also dissipated from the diode connection wires directly to the bus bars which are also arranged in the flow of cooling air.

A considerable saving on assembly ensues, since the bus bars are merely inserted into engagement means in insulating holders without a further working operation are then reliably and securely held by a locating device, particularly since the diode connection wires can be connected directly to the bus bars without other electrical connection members, cable shoes or the like by, for example, a softsoldering operation.

The short connection path between the respective diode and the bus bar results in a compact construction of the entire system, even when a large number of diodes are used, for example, up to seven diodes per heat sink in a preferred embodiment, three of which heat sinks are provided. At the same time a high degree of operational reliability is obtained.

The mounting device, in accordance with the invention, in conjunction with the rectifier system is satisfactorily vibration-proof and even allows individual diodes to be changed in the case of repairs without dismantling the entire system. Finally, the entire rectifier system is exchangeable and, if required, can also be used in existing three-phase generators and can replace the versions used hitherto.

It is particularly advantageous that the two bus bars which are normally used are off-set relative to one another in an axial direction and in a radial direction, so that the individual diode connections are readily accessible.

An embodiment of the invention is illustrated in the accompanying drawings, in which: Figure 1 is a plan view of a mounting device, namely a slip-ring end frame having a rectifier system, Figures la to 1c show details at the points at which the heat sinks and the holders are secured to the actual base plate, Figure 2 is a section taken on the line 2-2 of Fig. 1, and Figure 2a shows a detail of a heat sink which is equipped with diodes and which shows the possibilities for the electrical connection of this heat sink, Figures 3 to 5 are various views of the heat sink, Fig. 4 being a section taken on the line 4-4 of Fig. 3, Figure 6 is a section through an insulating holder or an insulator used for mounting the bus bars, Figure 7 is a plan view of one of the bus bars which is used, and Figure 7a is a section taken on the line 7 > 7aof Fig. 7.

The present invention entails securing, preferably bolting, three identical heat sinks, together with a respective insulator for mounting the holding bars, to four points on the base plate which accommodates that bearing of the armature shaft which is located at the slip-ring end. Each insulator has two rest grooves, which are staggered axially and radially relative to one another with respect to the slip-ring end frame, for receiving a respective bus bar, and optionally a further engagement means for receiving an electrical lead in a vibration-proof manner.

The mounting device is designated 1 in Fig.

1 and comprises a slip-ring end frame formed with an aperture 2 which accommodates the bearing (normally in the form of a roller bearing) at the slip-ring end and which, if required, at the same time acts as a contact surface for a brush-holder housing (not illustrated); and a rectifier system which is generally designated 3.

The mounting device has a base plate 4 formed by an outer ring 5 and an inner hub region 6 which is held by the outer ring 5 by means of intermediate rib portions 7 (see also Figs. lato 1 cm.

The mounting device is suitable for use in high-output three-phase generators which can be claw-pole machines or single-pole machines, both provided with slip-rings. The ring 5 5 of the base plate 4 can then be bolted, or secured in some other manner, to the external housing of the particular generator by means of the bores 8 distributed around the circumference, and a cover, optionally provided with air intake fittings and a distributor tube, can be provided.

The base plate 4 supports a plurality of heat sinks 9a, 9b, 9c, that is to say, in the present embodiment, three heat sinks which in turn can accommodate and support a predetermined number of diodes. The special wiring arrangement of the preferably identical heat sinks 9ato 9c is shown in greater detail in Figs. 3 to 5.

Otherwise, the base plate 4 can also be formed such that it has axial openings 10a, 10b, 10where the main parts of the heat sinks 9a to 9c are located, the heat sinks and the diodes carried thereby thus being arranged in the flow of cooling air, likewise bus bars 1 1 a and 1 1 b which are disposed further inwardly and are electrically and mechanically directly connected to the connection wires, generally designated 12, leading from the diodes.

In order to obtain an adequate number of degrees of freedom for effecting electrical connections in the case of the diodes, the heat sinks 9 a to 9 c, and the two bus bars 1 1 a and 11 b provided in the present embodiment, are insulated from one another, and also with respect to the base plate. In plan view, as is shown in Fig. 5, each heat sink 9 is of substantially crescent-shaped configuration and, as seen in the plan view of Fig. 1, each heat sink encompasses a quadrant of the base plate 4 and is thus connected to the base plate 4 at support points 13a, 13b, 1 3c and 1 3dwhich are offset by 90 relative to one another. The support point 1 3a, the support point 1 3b and the support point 13care again shown in detail in Figs. 1 b, 1 a and 1 c respectively, so that the connection of the fastening extensions 14a and 14b (Fig. 5) ant their correlation to the fastening points 1 3a to 13dank insulating holders 1 6 a to 1 6 d also secured at these locations for the bus bars 11 a, 11 b, may also be seen. Fig. 6 otherwise shows, in the form of a cross-section, the construction of an insulating holder 16 of this kind in greater detail.

Fig. 3 shows that the lateral support extensions 14a, 14b, each provide a fastening bore, and that the extensions are staggered vertically relative to one another, so that, for example, as is shown in Fig. 1 b, the first heat sink 9 a viewed in a clock-wise direction has its lower support extension 14a secured to the fastening location 13a by means of a screwthreaded bolt 18 which at the same time clamps the first insulating holder 16a viewed in a clock-wise direction, for the bus bars.

Securing of the heat sink and holder to the fastening location 13a is effected with interposed insulating washers 19 and an insulating tube 20 surrounding the bolt 18, and a further, larger diameter insulating sleeve 21 serving as a spacer. The holder 16a is itself made from an insulating material such as a thermoplastic and, as is also shown in the cross-sectional illustration of Fig. 6, has an extrusion-coated disc 22 of solid material such as metal, so that the nut 1 8 a associated with the bolt 18 can be tightened without damaging the plastics holder 16.

As shown in Fig. 1a, two support extensions 14b originating from different heat sinks 9aand 9b, that is, in this instance a support extension 14 b originating from the heat sink 9a and a support extension 14a originating from the heat sink 9b, together with the bus bar holder 1 6b located at this point, are held by the same bolt 18 at the fastening locations 1 3 b, likewise with interposed insulating washers 19 and an interposed insulating tube 20.

Support extensions of the heat sinks 9b and 9care then mounted in a corresponding manner at the fastening location 13c, whilst the fastening location 13tis shown in Fig. 1 c.

The only difference between this arrangement and the fastening location 13a shown in Fig.

1 b is that, in the present instance, the last support extension 14b is elevated, so that mounting is carried out either with an intermediate sleeve 21 or with an extended guide post 25 for the fastening bolt 18.

It will be seen that a total of three heat sinks 9ato 9cuniformly disposed around the circumference at intervals of 90 , and four insulating holders 1 6 a to 16dforthe bus bars 11 a, 11 b can be mounted by means of four fastening locations 13ato 13d, the heat sinks and the holders being optimally located in the flow of cooling air for the three-phase generator which is guided through corresponding cut-away portions or ventilation openings 1 0a to lOcin the base plate 4.

As is shown in Fig. 6, each insulating holder 16 has a rear fastening region 26 provided with a reception bore 27 for the bolt, and a widened portion 27a for receiving the head of the bolt and having a polygonal configuration complementary to the exterior configuration of the head of the bolt, whereby the bolt is secured against turning during assembly when the nuts 18 a are tightened. A forward reception region 28 extends substantially at right angles to the rear fastening region 26, both the regions being united to form a single part. The reception region 28 has engagement means or rest grooves 29a, 29band 29ceach having a rear wall formed by the material of the reception region 28, and a wall formed by a forward resilient tongue 30, the top end of the tongue having a barb-like configuration 31.

Each of the two rest grooves 29a and 29b serves to receive a bus bar which is shown in greater detail in Figs. 7 and 7a and which, in the illustrated embodiment, is fixed a total of four times by the holders 16ato 16d. As is shown in Fig. 7, the bus bars 11 define a polygonal form and are composed of short straight portions 32 and longer straight portions 33. The shorter straight portions 32 serve to mount the bus bars on the insulating holders 1 6 a to 16d, merely by inserting the shorter straight portions 32 of the bus bars into the rest grooves 29 and pressing them downwardly to such an extent that the barblike shape 31 springs forwardly from its pressed-back position which it assumed during insertion, and engages behind, and fixes, the inserted bus bar in a secure manner.

Thus, the bus bars are secured in one working operation and without further measures for securing them. The two bus bars are staggered axially and radially relative to one another by virtue of the different heights of the rest grooves 29a and 29 b receiving the bus bars, so that, in addition to the savings of space achieved thereby, the terminal wires 1 2 of the diodes inserted into the heat sinks 9a to 9care secured in a manner which does not present any problems.These diode terminal wires are connected directly to the bus bars without further electrical connection members or rigid or flexible leads and without cable shoes and without welded or pinched joints, by virtue of the fact that they are inserted into cut-away portions 33a in the longer straight portions 33 of the bus bars and are softsoldered directly at these locations. The soldered joints are designated 34 in Fig. 1.

The construction of the heat sinks shown in Figs. 3 to 5 will now first be discussed in detail. Each heat sink 9 has a central support region 35 which serves to receive, if desired, a number of diodes which are pressed directly into reception bores 36 which are drilled with high precision into the support region 35, one terminal of each diode thus also being directly and electrically connected. The diodes can be in the conventional form of so-called cup-type diodes and can be seen in greater detail at 37 in Fig. 2. They have a lower, optionally milled rim region which can be formed by a copper plate and which is press-fitted in the reception bores in the central support region 35 of the heat sinks.

In the illustrated embodiment, the support region 34 has six reception bores 36 for six power diodes, the terminal wires of half the diodes, that is to say, three power diodes in the present embodiment being electrically connected to one of the bus bars 11 a or 11 b and thus to a further three diodes on each of the other heat sinks. The correlation of the electrical polarities is in itself of little importance. However, the bus bars 11 a and 11 b can constitute the positive and negative bars respectively, so that the terminal wires of all the positive diodes are connected to the positive bar, and the terminal wires of all the negative diodes are connected to the negative bars. Two different types of diodes are located in each heat sink, namely diodes whose cathodes are connected to the outer diode housing and cathodes whose anodes are thus connected.A respective heat sink 9a, 9b, 9cis then provided for receiving the rectifier diodes for one phase of the stator winding and has three parallel-connected negative diodes and three parallel-connected positive diodes. Fig.

3 shows, as is also shown by broken lines as 38 in Fig. 2, that a reception bore 39 for an additional diode 40 is provided which, in the case of specific circuits, is in the form of a socalled excitation diode and is also connected in each case to one phase of the stator winding. Three excitation diodes are then provided, one terminal of each of which diodes (normally the cathode) is connected to the respective stator winding and its other terminal (normally the anode) being connected to the terminal D + of the regulator. Consequently, each heat sink is connected to the terminal of a phase winding U.V.W. of the star-connected or delta-connected stator winding, namely, as is shown in Fig. 5, by way of a connection lead 55 whose cable shoe 56 is, for example, screwed into a screw-threaded bore of the heat sink, as is shown at 57.A further reception bore for a bolt is designated 44 in Fig. 3 and, as is shown in Fig. 2a, serves, for example, for leading out a phase (W) by way of a connection lead 41 for connection of a tachometer.

In the lower portion as viewed in Fig. 3, the support region 35 of the heat sink 9 merges into a cooling fin portion 45 which has a large numer of individual cooling fins 46 which, as will be seen in Fig. 5, are of differing dimensions. The cooling fins 46 also extend at right angles to the support region towards the bus bars 11 a, 1 1 b which, as is shown in Fig. 1, are arranged further inwardly, so that the cooling fins and the bus bars are located in the most favourable region of the flow of cooling air.

The overall space-saving compact construction of the rectifier system ensures optimisation of the thermal conditions and a balanced cooling action even in the case of a large number of diodes which may be required in the case of three-phase generators having a "high" and a "very high" output.

As a result of the space-saving construction it is possible to combine a large number of terminal connections in the free circular segment formed between the heat sinks 9a and 9 C and, for example, as is shown by the hexagonal bolt 46, to connect them in an electrically conductive manner to the support plate 4 or to build up insulated intermediate fastening points to which external terminal connections, such as are designated 47, 48 and 49, are then connected. Furthermore, it is possible to dispose conventional suppressor capacitors at 50 which are also able to block peak loads for the diodes. Since the present invention chiefly involves the mechanical conditions of the arrangement of the rectifier system, there is no need to show the electrical connections in detail. Electrical leads 51, 52 and 53 coming from the heat sinks, and which also can be the terminal wires of the separate excitation diodes 40, are pressed into the bottom rest grooves 29 C additionally provided in the insulating holders, and are retained therein in a vibration-proof manner.

The axial and radial offset of the bus bars 11 a and 11 b renders it possible to provide a more compact construction and, nevertheless, to ensure optimum accessibility. Furthermore, these bus bars are also disposed within the flow of cooling air, so that they can draw heat from the diode terminal wires in order to obtain a balanced cooling action on the diodes.

Fig. 7 shows that at least one of the bus bars 11 has an outwardly bent-back portion 32a which can be used for the securing of continuing leads, as is indicated at 54 in Fig.

Claims (14)

1. Holding and mounting device for the mounting of rectifier diodes, their heat-sinks and terminal connections in a rotating electrical machine, wherein the device comprises a base plate, and a plurality of mutually electrically insulated heat-sinks having support extensions, for mounting the rectifier diodes, which support extensions together with insulating holders for receiving bus bars are secured to location points distributed around the circumference of the base plate; the latter being provided with a central bearing bore for the rotor shaft.

2. A device as claimed in claim 1, wherein three heat sinks are used each equipped with a plurality of diodes, and four fastening points are uniformally distributed around the periphery near to the outer circumference of the base plate, between which fastening points are disposed holes of such shape and size that the heat sinks extending from fastening point to fastening point, and bus bars, are located in the path of the holes.

3. A device as claimed in claim 1 or 2, wherein holders are provided for the bus bars and have a fastening region which incorporates a reception bore and by means of which the holders are secured to the fastening loc; tions together with the support extensions, and a reception region which has a plurality of rest grooves into which the bus bars are engaged.

4. A device as claimed in claim 3, wherein the rest grooves have forward, resilient tongues whose upper portions have a barblike configuration such that the tongues, after an initial yielding thereof, engage behind the bus bars inserted into the rest grooves.

5. A device as claimed in any of the claims 1 to 4, wherein the bus bars mounted in the rest grooves in the holders are offset inwardly relative to the heat sinks containing the diodes, such that the connection leads of the diodes abut against their associated bus bars.

6. A device as claimed in claim 5, wherein the bus bars have notches into which the connection leads of the diodes are inserted and soft-soldered.

7. A device as claimed in any of the claims 1 to 6, wherein the bus bars define a polygonal form comprising alternate short and long sides with the former being seated in the rest grooves in the holders.

8. A device as claimed in any of the claims 1 to 7, wherein -the reception region of the holders has at least one further rest groove for receiving electrical leads which originate from the heat sink and/or from special diodes inserted into the heat sinks, and which are connected to a further connection point.

9. A device as claimed in any of the claims 1 to 8, wherein a support region of each heat sink has a plurality of reception bores into which are pressed diodes whose connection leads are connected directly to the two bus bars, two rows of three diode reception bores are formed in each heat sink, and the bus bars are staggered in an axial and in a radial direction relative to one another such that a top row of three diodes is connected to a a nearer and higher bus bar, and a bottom row of three diodes per heat sink is connected to a remoter and lower bus bar.

10. A device as claimed in any of the claims 1 to 9, wherein a suppressor capacitor is secured in the space between a first heat sink and a third heat sink, which heat sinks occupy a respective quadrant of the base plate and between which is located a further quadrant occupied by a central heat sink.

11. A device as claimed in any of the claims 1 to 10, wherein there is arranged in the space between the first heat sink and the third heat sink at least one support point to which are secured electrical leads which originate from the heat sinks and/or the special diodes let into the heat sinks.

12. A device as claimed in any of the claims 1 to II, wherein the fastening location for the heat sinks or the bus bar holders incorporate bores which are optionally surrounded by upwardly drawn flanges on the base plate and through which bores are guided bolts which, by means of insulating sleeves and insulating washers, simultaneously clamp and fix the support extensions of the heat sinks and the rear fastening regions of the holders.

13. A device as claimed in claim 9 or any of claims 10 to 12 as dependent thereon wherein there is disposed in each heat sink a further reception bore in which is arranged a diode having a separate lead.

14. A holding and mounting device substantially as hereinbefore described with refer- ence to the accompanying drawings.