Reversing contactor for a three-phase motor

This invention pertains to a three-phase reversing contactor with fixed-mounted contact parts serving the input and the output, and a connection by contact bridges from the input to the output. A common drive mechanism is provided for all the contact bridges, and a shift mechanism to change the configuration of the contact bridges, while in the OPEN position, relative to the fixed-mounted contact parts is also provided. Through the application of the two independently movable contact bridge carriers, which by use of an auxiliary magnet can be selectively brought into functional contact with the common drive mechanism by a reversing yoke, the drive output for the auxiliary magnets can be kept low. As there is a fixed configuration of contact bridges to the fixed-mounted contact parts, the major wiring work can be performed in the shop by the use of correspondingly formed fixed-mounted contact parts.

BACKGROUND OF THE INVENTION 
This invention relates to the field of three-phase contactors and more 
particularly to such contactors for use with electric motors which provide 
for the reversing of rotational direction from right to left or from left 
to right, having fixed-mounted contact parts serving the input and output 
lines, contact bridges connecting the input and output lines, equipped 
with a drive, and a positioning mechanism to shift the input and output 
lines between configurations with respect to another. 
In a known reversing contactor disclosed in DE-OS 23 14 597, an additional 
rotary drive for the contactor bridges, which can be driven by a toothed 
rack, is provided. Such a contactor represents a relatively complicated 
design incurring high material costs and high assembly costs during 
manufacture. 
It is an object of this invention to simplify substantially the known 
reversing contactor in terms of design and expense. 
SUMMARY OF THE INVENTION 
Briefly stated, in accordance with the invention, the foregoing objects are 
achieved in a simple fashion by providing contact bridges which are held 
grouped in place in two separate contact bridge carriers and which can be 
selectively coupled to a drive mechanism by a positioning mechanism. The 
activation of the positioning mechanism requires only slight activating 
forces. A further advantage of this invention is that the drive mechanism 
does not have to accelerate unnecessarily large masses. 
In another aspect of the invention, the positioning mechanism is 
constructed of a yoke which can be reversed by use of an auxiliary magnet 
and is connected in a rotating fashion to the switching magnet whose free 
end can mesh selectively with the parallel-aligned, shiftable, contact 
bridge carriers, then this positioning mechanism only needs to rotate the 
reversing yoke which has a relatively low mass since the switch-over must 
take place while the contactor is off. To prevent any actuation of the 
individual contact bridge carriers when the reversing yoke is not in the 
above-described position, it is advantageous to provide locking lugs on 
the contact bridge carriers which mesh with the cutouts in a locking bar, 
shiftable by the reversing yoke. The locking bar has the additional 
advantage that the reversing yoke is forced back into its rest position 
when the auxiliary magnet is not energized. Additionally, in order to 
permit an electrical interlock it is further advantageous if the locking 
bar has an integral auxiliary contact. Manual actuation of the positioning 
mechanism and also external indication of this position can be attained if 
the locking bar has an extension protruding beyond the outer body of the 
contactor. 
In a further aspect of the invention, the relatively high assembly costs 
incurred during installation or pre-wiring of the reversing contactor is 
reduced if fixed-mounted contact parts are bridged within the contactor 
housing, and only one terminal provided per line connection which is 
accessible from the exterior of the contactor housing. The wiring expense 
is further reduced by having a lock-type NOC (normally open contact) 
actuated by the drive independently of the positioning mechanism connected 
at one end of the left and right-turning common output line within the 
contactor and having its other side to a connecting terminal accessible 
from the exterior of the contactor housing. The wiring expense is further 
reduced and lesser actuation forces required for the positioning mechanism 
when reciprocal interlocking contacts are connected within the contactor 
before the connecting terminals for right and left rotation.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
In the schematic according to FIG. 1, motor 1 with connection U, V, W is 
connected through bridges 2, 3 and 4 to phases T, S, R. The switching 
force is generated by the switching magnet 5. The positioning of the 
contact bridges 3 and 4 is performed by magnetic drive 6. The 
fixed-mounted contact parts which are essential for the generic invention, 
are designated by reference symbols 7 to 11. In the position shown in FIG. 
1, the fixed-mounted contact parts 7, 8 are bridged by contact bridge 4 
and the fixed-mounted contact parts 9 and 10 by contact bridge 3, i.e., 
connection U of motor 1 are connected to phase R, and connection V of 
motor 1 is connected to phase S of the switch input. If magnet drive 6 is 
electrically energized, then the contact bridges are shifted in the 
direction shown by arrow 12 so that the fixed-mounted contact parts 8, 9 
are bridged by contact bridge 4 and the fixed-mounted contact parts 10, 11 
are bridged by contact bridge 3 so that connection U of the motor passes 
through to phase S, and connection V of the motor through to phase R. The 
only wiring cost is the bridge from the fixed-mounted contact parts 7 to 
the fixed-mounted contact part 11. The arrangement for right rotation of 
the bridges in reference to the fixed-mounted contact parts can be seen in 
FIG. 2. 
FIG. 3 shows a contemplated embodiment having bridges 3 and 4 as U-shaped 
contact bridges with the fixed-mounted contact parts 7 through 11. In this 
design the fixed-mounted contact parts 7 to 11 correspond to the normal 
fixed-mounted contact parts of five adjoining individual contacts of a 
standard contactor. Only the contact bridge carrier has been modified as 
shown in FIG. 4. Part 14 of the contact bridge carrier connected to the 
armature 13 bears the movable part 15 in whose cutouts 16 contact bridges 
3 and 4, respectively are held in place with the legs of the U in the 
normal fashion using contact pressure springs. The forks 17, 18 and a 
slide pin 19 control the movable mount. The prongs of forks 17, 18 at the 
same time provide the stops for the movable mount. The movable coupling of 
the movable part 15 to magnetic drive 6 can be seen in FIG. 6. This is 
handled by a spring member 20 which meshes at one end with the armature 21 
of the magnetic drive 6 and at the other end with the ends 22 in a keyway 
23 of the movable part 15 in order to thereby bring about movement. 
In the embodiment shown in FIG. 7 the entire armature 13 is shifted 
sideways by the core 24 of the magnetic drive 6 with the contact bridge 
carrier 25. The shift is provided for by alignment case 26 for the 
transverse motion. The motion is limited in such a fashion that armature 
13 does not make contact with core 24. In ordr to have the complete 
switching capability available, core 27 of switching magnet 5 is wider 
than armature 13. To prevent the contact bridges 3, 4 from making contact 
with the fixed-mounted contact parts 7 through 11 during transit positions 
when switching on the switching magnet, an alignment pin 28, shown in FIG. 
8, is mounted in the movable part 15 of the contact bridge carrier for a 
mechanical interlock with the pin, penetrating into one connecting member 
29 of the contactor housing. The connecting member has the U-shape as seen 
in FIG. 8 with the legs or end sectors 30, 31 and the oblique surface 34, 
with the length 32 of the end sector 31 being greater than the NOC 
penetration pressure. Depending upon the time factor between the 
transverse motion, i.e. start-up of the positioning mechanism by magnetic 
drive 6 and initiation of the switching motion, i.e. electrically 
energizing the switching magnet 5 due to the tolerances, temperature, 
varying accelerations, etc., the free area designated as 33 in the 
connecting member through which aligning pin 28 is passed. Thereby the 
switching time is reduced. The end sector 30 corresponds to the right 
rotating position of the contact bridges in accordance with FIG. 1. End 
sector 31 corresponds to the left rotating position as can be seen from 
FIG. 2, i.e., when magnetic drive 6 is switched on. 
In the embodiment shown in FIG. 9, a wire-formed reversing yoke 35 having 
one end 36 is movably connected to the common drive 5 which is comparable 
to the switching magnet in standard contactors. Free end 37 can 
selectively slide into a cutout 38 or 39 in two separately movable contact 
bridge carriers 40 or 41 aligned within the housing. The positioning 
mechanism handles that task with magnetic drive 6 functioning as the 
auxiliary magnet. 
In the embodiment shown in FIGS. 10 and 11 the contact bridge carriers 40 
and 41 are equipped with extensions 42 into which the cutouts 38 or 39 are 
incorporated. The contact bridge carrier shown in FIG. 12 is the one shown 
on the right hand side of FIG. 11. The left contact bridge carrier 41 is 
inserted at a 180-degree rotated alignment so that both extensions 42 are 
more or less facing each other and enclose between them cutouts 38, 39. 
Free end 37 of the reversing yoke 35 is captured in these cutouts. Each of 
the contact bridge carriers has four access slots 43 in this embodiment, 
wherein the contact bridges 44 with the non-depicted contact pressure 
springs are housed in a standard fashion. The access slots 43 are 
positioned in pairs beside and above each other. By designing the 
reversing yoke 35 as a wire yoke, it is possible to align the magnetic 
drive 6 between the switching magnet 5 and the contact bridge carriers 40, 
41. The armature 21 of the magnetic drive 6 meshes with a cutout 45 of a 
locking bar 46, which is movable and can reset the reversing yoke 35 into 
both end positions using the carriers 47. The end position shown in FIG. 
10 is attained by the counter-pressure spring 48 which meshes with the 
movably aligned locking bar 46. This predetermined positioning is always 
maintained when magnetic drive 6 is not excited. If armature 13 is drawn 
down towards the not depicted core 27 by electrically charging the 
switching magnet 5, then contact bridge carrier 41 is carried along 
towards switch-on via the reversing yoke 35. The contact bridges 44 
thereby come in contact with the stationary contact parts, as will be 
further elaborated below. Thereby, a locking lug 49 on extension 42 mates 
with a blocking cutout 50 in the locking bar 46 so that any motion of the 
locking bar 46 by magnetic drive 6 is excluded. If magnetic drive 6 is 
electrically energized, then the locking bar 46 shifts counter to the 
force of spring 48 until the free end 37 of the reversing yoke 35 meshes 
with cutout 38 and locking lug 49 of the other contact support 41 mates 
with the other locking cutout 50 in locking bar 46. If then switching 
magnet 5 is activated, contact bridge carrier 41 is attracted and the 
corresponding contacts--to be further explained below--are established. 
As FIGS. 13 through 15 show, not every contact bridge is allocated a 
connecting terminal on the facing sides of the contactor. Rather, only the 
necessary main terminals and, if necessary, usable auxiliary switch 
terminals are routed to the outside. The terminals are indicated by a 
square and can be seen in FIG. 15 as a screw-in connection. FIG. 16, for 
example, depicts the fixed dual contact piece of the middle fixed contact 
part of the lower level in accordance with FIG. 14. The square depicted 
opens eyelet 51, for example, or the combination connecting screw 52. FIG. 
17 depicts the dual fixed contact piece of the two middle contact 
locations of the upper level. Bridging of the fixed contact pieces in the 
manner shown is indicated by the lines 53. The lines 54 in FIG. 13 show 
the internal cross-over wiring between the fixed contact pieces on two 
levels. Here the contact piece combination, as shown in FIG. 18, is 
utilized. As can be seen here as well, connector terminals are only 
present in the lower level. 
To determine the individual contact bridges or terminal connections 
corresponding to the respective input and output line, please refer to 
FIG. 20. The non-reversible contact bridge 2 in this instance is 
positioned at phase T (see also FIGS. 1 and 2). Independently of the 
reversing yoke 35, the contact bridge is brought into functional 
connection with the switching magnet 5 so that the terminals designated 56 
and 57 in the lower portion of the reversing contactor are electrically 
connected. The contact bridges 3 and 4 are positioned in the two interior 
access slots of the contact bridge carrier 41 laying one upon the other in 
two levels, i.e., facing the other contact bridge carrier. The contact 
bridges 54, 55 mounted in adjacent slots of the contact bridge carrier 40 
which can be independently moved, are in the above-described manner 
completely interlocked. The input line or connecting terminal for the 
fixed contact parts in reference to contact bridge 3 or 55 is designated 
by number 52. The corresponding output line, which was also bridged as 
described above in greater detail, is designated 58 as the connector 
terminal. The connector terminal for the common input line for contact 
bridges 4 and 54, which was also bridged in the above-described fashion, 
is designated 59, and the joint output line is designated 60 as the 
connctor terminal. No designation was given to the connecting terminals 
for the external auxiliary contact circuits. 
The control with the corresponding interior wiring can be seen in FIG. 19. 
The on-switch or on-key for the right rotation is designated 61, and the 
one for left rotation is designated 62. The off-key 63 designed as a 
normally closed contact (NCC) is positioned with both on-keys at the input 
line 64. The left on-key 62 is connected at its other end over an 
interlock NCC 65 to the coil of magnetic drive 6 and to an NOC 66 actuated 
by the magnetic drive; this NOC connects the core of switching magnet 5 
via terminal 67 to the output line 68 of the power system. The coil of the 
magnetic drive 6 is connected by a self-cleaning contact 69 to terminal 67 
which is required as long as the coil for magnetic drive 6 is not sized 
for 100% switch-on duration. The self-cleaning contact 69 is actuated by 
the switching magnet 5. The end of the coil for a switching magnet 5 
facing the input line is connected on the one side with the other end of 
the NOC contact 66, with the one end of the interlocking contact 70 
opposing the interlocking NCC contact 65, and with a self-locking contact 
71 activated by the switching magnet 5. The other end of the self-locking 
contact 71 is connected to terminal 72 of the reversing contactor so that 
it can be brought into contact with the off-key 63. The connector 
terminals passing to the outside, which ought to be connected to the 
on-key 61 or on-key 62, are identified as 73 and 74. 
It is clear based on FIG. 9 in conjunction with FIGS. 13 and 15 that the 
reversing contactor in accordance with this invention can be installed 
with very little assembly labor when connecting the contactor, since the 
internal wiring can be handled in the shop which, given mechanized 
fabrication, is substantially more cost-effective than on-site wiring. 
As will be evident from the foregoing description, certain aspects of the 
invention are not limited to the particular details of the examples 
illustrated, and it is therefore contemplated that other modifications or 
applications will occur to those skilled in the art. It is accordingly 
intended that the claims shall cover all such modifications and 
applications as do not depart from the true spirit and script of the 
invention.