Detachable plug and track receptacle for electrical connections

A plug is coupled to a receptacle by means of a projecting rim on the base of the plug which engages a flange of the receptacle. The receptacle contains at least two electric current conductors extending in a longitudinal direction. Contact pins in the plug are mounted on a contact pin support which is spring loaded in the plug housing. The housing base can be inserted in the receptacle when the housing is oriented transverse to the longitudinal direction. Supporting blocks on the contact pin support then engage the flanges on the receptacle to cause the pins to recess in the housing against the spring forces. Upon rotating the housing 90.degree., the projecting rim of the base engages the flanges of the receptacle and the supporting blocks enter the receptacle, due to the springs, causing the contact pins to engage the current conductors.

BACKGROUND OF THE INVENTION 
The invention relates to a combination of a plug, suitable for connection 
to a current-consuming device, for example a lamp, and a track receptacle 
having at least two mutually insulated current conductors. The plug is 
provided with at least two electrical contact pins for contacting the 
conductors in the receptacle and comprises a first part and a second part 
which is movable relative thereto. These parts are held in a first 
relative position by at least one spring. When the plug is coupled to the 
receptacle the force of the spring also provides the contact pressure 
between the contact pins and the current conductors. The receptacle 
encloses a space which is accessible via an opening extending in a 
longitudinal direction of the receptacle. The opening is bounded by two 
flanges. The plug includes electrically insulating supporting blocks 
arranged in such a manner that, when the plug is coupled to the voltage 
rail, these blocks are located between the facing edges of the two flanges 
and close fit each of two facing edges of the flanges in at least two 
different places. 
Such a combination is disclosed, for example, in Netherlands Patent 
Application No. 7113699. An advantage of this known combination is that 
the moment of force which may be exerted by the current-consuming device 
connected to the plug is exerted only on the first part of the plug and 
the contact pressure between the contact pins and the current conductors 
obtained by spring action is not influenced by it. Furthermore, when the 
plug is coupled to the receptacle, the plug cannot be rotated about an 
axis perpendicular to the receptacle. 
The disadvantage of the known combination is that upon coupling the plug to 
the receptacle, the contact pins can contact the current conductors before 
the current collector has reached its fixed final position with respect to 
the voltage rail. 
SUMMARY OF THE INVENTION 
In order to avoid this disadvantage, the invention provides a combination 
of the kind described above which is characterized in that upon coupling 
the plug to the track receptacle, the supporting blocks in the first 
relative position of the plug bear on or against the flanges of the 
receptacle and the first part of the plug includes a base member which can 
be inserted against the force of the spring into the space enclosed by the 
receptacle. Insertion of the base causes the second part of the plug to 
move relative to the first part from the first relative position to a 
second relative position. With the base inserted, and during rotation of 
the plug with respect to the receptacle to cause the base member to engage 
and lock behind the flanges, the first and second parts are held in their 
second relative position until a rotational position is reached when the 
blocks are able to, under the restoring force of the spring, enter the 
space between the facing edges of the flanges. At this point, the first 
and second parts reassume their first relative position with the contact 
pins contacting the current conductors under the force of the spring. 
An advantage of this combination is that contact between contact pins and 
current conductors cannot occur until the final coupled position has been 
reached. A further advantage is that the supporting blocks also serve to 
position the plug relative to the receptacle.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
In FIG. 1, A denotes a track receptacle, in which 1 is an aluminium housing 
whose flanges 2 bound an opening 3 extending over current conductors 6a, 
6b, and 6c in a longitudinal direction of the receptacle. The opening 3 
gives access to the space 1c enclosed by the receptacle. A conductor 4, 
for grounding the receptacle, is provided in one of the flanges. 
A holder 5 of synthetic resin is clamped against one side of the aluminum 
housing by means of locking ribs 1a. Holder 5 is provided with three 
mutually insulated current conductors 6a, 6b and 6c at mutually equal 
distances. The central current conductor 6b lies in the plane of symmetry 
of the holder 5 of synthetic resin. 
The receptacle can be secured, for example, to a wall or ceiling via an 
aperture 1b provided in the aluminum housing 1. 
The letter B denotes the plug, 10 denoting a first part of the plug, the 
plug housing. The first part 10 has a base 11 comprising projecting rims 
11a on either side. The base 11 has a recess 12 through which contact pins 
15 project. The base 11 further comprises two diametrically opposed 
contact points 4a one of which cooperates with the conductor 4 of the 
receptacle when coupled to the plug. 
Together with supporting blocks 16, which each comprise a supporting face 
16a, and grips 17, the contact pins 15 form part of a second part 18 (FIG. 
2), a contact pin support of the plug. In the situation shown in FIG. 1 
the second part 18 is in the first position relative to the first part 10, 
the contact pins extending out of the recess in the base and the 
supporting blocks extending out of the recesses in the housing. 
The first part 10 of the current collector has a cylindrical portion 20 to 
which a current-consuming device, for example a lamp, can be connected. A 
cover 21 is also connected to the first part by means of screw 23. 
In FIG. 2, which shows the construction of the plug B, it can be seen that 
the cover 21 has two supporting points 24 on which one end of springs 25 
bear. The other ends of the springs 25 press against bosses 26 in the 
second part 18 of the plug. Since the cover 21 is secured to the first 
part 10 by screw 23, the second part 18 can be moved relative to the first 
part 10 against the force of the springs 25. 
The coupling of the plug B to the receptacle A will be explained in FIGS. 3 
to 5. In FIG. 3, the plug is placed on the rail in an initial position in 
which the supporting faces 16a of the supporting blocks 16 bear on the 
flanges 2 of the receptacle. Both the contact pin support and the plug 
housing are oriented transverse to the longitudinal direction of the 
receptacle. The second part 18 of the plug is in the first position 
relative to the first part 10. A lamp 29 is connected to the first part 10 
of the plug. 
By moving the first part 10 of the plug in the direction denoted by the 
arrow 30, the second part 18 of the plug is moved to a second position 
relative to the first part 10. This situation is shown in FIG. 4. In this 
situation the base 11 is now projecting through the opening 3 into the 
space 1c enclosed by the receptacle A. 
The plug B is then moved to a final position, the coupled position, by a 
rotating it through approximately 90.degree. about axis 40 through base 
11. Both the contact pin support and the plug housing are now oriented 
along the longitudinal direction of the receptacle. The coupled condition 
is shown in FIG. 5. In this coupled condition the second part 18 of the 
plug again assumes the first position relative to the first part 10, since 
blocks 16 now enter space 1c under the force of springs 25. The contact 
pins 15 now contact two current conductors 6b and 6c, while the supporting 
blocks 16 are substantially entirely within the enclosed space 1c and each 
closely fit one of the two facing edges of the flanges 2. As a result of 
this, further rotation of the plug B about the axis 40 is not possible. 
The projecting rims 11a of the base 11 cooperate with the flanges 2 in 
such manner that movement of the plug as a whole in a direction 
perpendicular to the receptacle is not possible. However, it is possible 
to slide the plug along the longitudinal direction of the receptacle. 
For uncoupling the plug B, first the second part 18 will have to be moved 
against the spring force into the second relative position by means of the 
grips 17. The plug can then be rotated as a whole about the axis 40 to its 
initial position, after which the second part 18 will be moved by the 
spring pressure to the first position relative to the first part 10, 
during removal of the plug from the receptacle. 
As a result of the asymmetric location of one of the contact pins of plug B 
it is also possible to couple the plug in a position rotated 180.degree. 
about an axis perpendicular to the receptacle. The advantage of this is 
that the plug can be connected with one of its contact pins 15 to either 
one of the two conductors 6a and 6c which can be switched independently of 
each other, the conductor 6b constituting the common return current lead. 
Although in this embodiment a plug has been described which is suitable for 
coupling to a receptacle having three mutually insulated current 
conductors, it will be obvious that the plug embodying the invention may 
alternatively be used in a receptacle having two or more than three 
mutually insulated current conductors. 
Finally it is to be noted that in this embodiment a lamp 29 is connected to 
the plug by way of example. It is alternatively possible, however, to 
connect other types of current-consuming devices to the plug either 
directly or via an electric cable.