Connector for a power supply

Details Connector for a power supply Connector for a power supply

1998-12-21

2001-02-27

Abrams, Neil (Department: 2839)

Electrical connectors

With supporting means for coupling part

Coupling part or mating part extending into panel opening

Reexamination Certificate

active

06193548

ABSTRACT:

FIELD OF THE INVENTION
This invention relates generally to a connector for a power supply such as a welding power supply and, in particular, to a connector that reduces the likelihood of shorting out or breaking over or arcing from the internal or external electrical connection (which may be electrically hot) to the power supply chassis.
BACKGROUND OF THE INVENTION
Power supplies such as welding power supplies are used to provide high amperage current. Typically, in a welding power supply, a pair of output terminals is provided. A welding cable connected to the welding torch (or stinger, drive assembly or welding circuit) is inserted into one of the two output terminals. The other output terminal receives a welding cable which is connected to the workpiece being welded. Typically, the connectors are twist lock type connectors (also called international connectors), the power supply has a female connector, and the welding cable has a mating male connector. In some designs the cable has a female connector and the power supply a male connector.
One prior art twist lock connector is shown in
FIGS. 1-3
. The prior art connector, as shown in
FIG. 3
, includes a twist lock receptacle
101
, a front bulkhead insulator
102
, a rear bulkhead insulator
103
, a lock washer
104
, a nut
105
, a washer
106
, a lock washer
107
and a hex bolt
108
. Hex bolt
108
and washers
104
,
106
and
107
are comprised of zinc plated steel, and twist lock connector
101
and nut
105
are comprised of brass. The front and rear bulkhead insulators,
102
and
103
are phenolic. The steel and brass components are used to provide for adequate electrical contact. A phenolic is typically used because it is a good insulator, flame-retardant, and will not melt.
Referring now to
FIG. 1
, a view of the prior art connector from outside the power supply is provided. Front bulkhead insulator
102
includes a ridge, as depicted by the concentric circles of FIG.
1
. The inner perimeter of front bulkhead insulator
102
is hexagonal in shape. A twist lock receptacle
101
has a hexagonal outer perimeter and fits tightly within front bulkhead insulator
102
. Twist lock receptacle
101
includes a circular opening
116
having an axial notch
115
. A circumferential, slightly helical, notch
117
, within twist lock receptacle
101
, may be seen in
FIGS. 2 and 3
. When the welding cable is connected, a key on the male connector attached to the welding cable mates with notch
115
, and when the cable connector has been inserted all of the way, the cable connector is rotated and the key turns in circumferential notch
117
. The male connector is pulled tightly to the face of the female connector by the action of the helical-shaped notch. Thus, the cable connector is locked into place and the desired electrical contact is obtained.
Referring now to
FIG. 2
, front bulkhead insulator
102
is inserted into a hole in a power supply chassis
112
. The hole in power supply chassis
112
includes a notch which receives a key
119
on front bulkhead insulator
102
. Thus, front bulkhead insulator
102
does not twist when the male connector on the welding cable is being rotated to lock it into place.
An end
120
of twist lock receptacle
101
extends within the welding power supply and rear bulkhead insulator
103
is mounted thereon. Rear bulkhead insulator
103
and front bulkhead insulator
102
are designed to mate and welding power supply chassis
112
is sandwiched between them. Also, the notch on front bulkhead insulator
102
is received in a similarly and oppositely notched portion
122
of rear bulkhead insulator
103
, to prevent the inner portion of the connector from rotating.
Inner end
120
of twist lock receptacle
101
is threaded and nut
105
has mating threads to allow nut
105
to be threadedly mounted on twist lock receptacle
101
. Thus, nut
105
and lock washer
104
are used to maintain contact between front bulkhead insulator
102
, welding power supply chassis
112
and rear bulkhead insulator
103
.
End
120
of twist lock receptacle
101
is hollow, and its inner surface is threaded. The threaded interior portion receives hex bolt
108
, about which washer
106
and lock washer
107
are disposed. As shown in
FIG. 2
, an internal electrical connection
110
is placed between the inner end of twist lock receptacle
101
and washer
106
. The internal electrical connection
110
may be a copper lug, an aluminum bus bar, or any other internal electrical connection. Some prior art connectors include a gas fitting that replaces hex bolt
108
, and an O ring disposed within twist lock receptacle
101
near notch
117
that seals the gas flow path (through the connector and into the cable).
Thus, it may be seen that the prior art connectors provided for a secure and locking electrical connection between an internal electrical connection and the welding cable.
It is not unusual for welding power supplies to be used outside, for example at construction sites. Thus, they are often exposed to rain or may otherwise get wet. Also, to obtain IEC certification.(or other certifications such as UL, CSA, NEMA etc.), welding power supplies must be subjected to a “rain test”. In such a test, the power supply will be subjected to water, to ensure that premature failures in the field will not occur.
However, in the prior art connectors water sometimes seeps between front bulkhead insulator
102
and welding chassis
112
. The water then seeps down between front bulkhead insulator
102
and rear bulkhead insulator
103
. The potential water leakage path is labelled
118
, and is shown as a solid black line. As water leaks in along path
118
, it may provide a conductive path from twist lock receptacle
101
, which is electrically hot, to chassis
112
, which should be grounded. Thus, this path may provide an undesirable short.
It is typical to provide a welding power supply with a high frequency arc starter. A high frequency arc starter provides a low current, but high voltage, high frequency signal. Such a high voltage signal can arc along path
118
from twist lock receptacle
101
to welding power supply chassis
112
. This problem is exacerbated when water seeps into path
118
.
One prior art attempt to solve the problems of water leakage and high frequency arcing is to apply a RTV (room temperature vulcanizing) compound in an attempt to seal path
118
. However, such a compound is difficult to apply and does not adequately solve the problem. Additionally, a second potential water seepage path
118
A may be found between twist lock receptacle
101
and front bulkhead insulator
102
.
Accordingly, it is desirable to provide a power supply connector that will reduce the likelihood of water leaking into the power supply and causing a short therein, or to have a short during high frequency arc starting. Such a connector should preferably be a locking cable receptacle, with an anti-rotational fitting and relatively simple and easy to manufacture.
SUMMARY OF THE PRESENT INVENTION
One aspect of the invention is a power supply connector that includes a cable receptacle. A front bulkhead insulator and a rear bulkhead insulator are mounted on the cable receptacle. At least one O ring is disposed between the front and rear bulkhead insulators, to seal out water. In alternative embodiments the front bulkhead insulator includes a stepped portion that mates with a stepped portion on the rear bulkhead insulator. The front bulkhead insulator may provide for an elongated path from the chassis to the cable receptacle. Also, an O ring may be disposed between the cable receptacle and the front bulkhead insulator, to seal out water. The connector may be a twist lock connector, and the chassis may be placed between the bulkhead insulators.
Another aspect of the invention is a power supply connector including a cable receptacle. A front bulkhead insulator mounts on the cable receptacle, and on the welding power supply chassis. A rear bulkhead insulator is also mounted on the cable receptacle and the welding power supply ch

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