Information
-
Patent Grant
-
6648692
-
Patent Number
6,648,692
-
Date Filed
Monday, September 30, 200221 years ago
-
Date Issued
Tuesday, November 18, 200320 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Reichard; Dean A.
- Lee; Jinhee J
Agents
- Quarles & Brady
- Gerasimow; Alexander M.
- Walbrun; William R.
-
CPC
-
US Classifications
Field of Search
US
- 439 621
- 439 716
- 439 622
- 439 620
- 337 33
- 361 41
- 361 833
-
International Classifications
-
Abstract
An in-plane fuse adapter provides a conductive extension that may be received by a standard terminal of a terminal block relay or the like to present side surfaces conforming substantially to the width of the terminal block relay allowing other terminal blocks to be closely abutted to the left and right side of the terminal block relay when it is attached to a connector rail. A wire terminal is held by the housing and attached to the second socket positioned to receive and retain an external electrical conductor of a type normally received by the plurality of terminals of the terminal block relay.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
BACKGROUND OF THE INVENTION
The present invention relates to narrow-profile, terminal block relays and in particular to a method of adding electrical fuses to such relays.
“European style” terminal blocks provide a method of electrical interconnection of industrial control components. These terminal blocks have a narrow and flat shape that allows them to be stacked together in close proximity when mounted on a DIN rail. When so stacked, wires may be received at terminals along the upper and lower edge of the terminal blocks.
The terminals allow connection to other wires connected to other terminals or to the leads of electrical components supported by the terminal block. Such electrical components may include fuses, indicator lights, and relays.
For a terminal block holding a relay (“a terminal block relay”) or a fuse (“a terminal block fuse”), the relay or fuse is typically received by a socket at the front edge of the terminal block. The housings holding the relay or fuse are designed to have a width no greater than that of the terminal block, typically between 5 to 14 mm, to minimize space occupied on the DIN rail.
Programmable logic controllers (PLCs) are industrial computers used for the control of machines and processes. A PLC has input and output circuits that may connect to sensors and actuators on controlled machines and by executing a standard control language, such as relay ladder language, the PLC may read the inputs and according to the execution of the control program, provide outputs controlling the machine.
Terminal block relays are often used with a PLC, the latter which may be attached to the same DIN mounting rail on which the terminal block relays are mounted. Outputs from the PLC are connected to the coils of terminal block relays whose contacts in turn connect to the desired machine actuator to provide a form of isolation.
When the contacts of a terminal block relay are connected, for example, to an inductive load, a fuse may be placed in series with those contacts. This normally entails placing a fuse terminal block adjacent to each terminal block relay doubling the required space needed on the mounting rail. When many outputs to inductive loads are required, the amount of space on the rail is quickly exhausted.
SUMMARY OF THE INVENTION
The present invention provides a fuse adapter for adding a fuse to a terminal block relay without using additional space on the mounting rail. The fuse adapter also minimizes the wiring required to add a fuse to a terminal block relay.
Generally, the fuse adapter has a narrow housing holding a fuse and providing a conductive extension that may engage a terminal of the terminal block relay to mechanically and electrically fix the fuse adapter to the terminal block. When so fixed, the fuse adapter lies within the width of the terminal block relay so as not to interfere with adjacent terminal blocks. The fuse adapter provides an additional terminal that may receive a wire to connect the internal fuse in series between the received wire and the conductive extension. The fuse adapter also has the benefit of allowing the fuse to be replaced in the future, by providing a means of entry to the fuse adapter in the event it ‘open” or warrants replacement in the circuit.
Specifically then, the present invention provides an in-plane fuse adapter for use with a terminal block relay, the terminal block relay being of a type mountable at its rear surface on a laterally extending rail to present a substantially constant lateral thickness between left and right planar walls each which may abut corresponding planar walls of adjacent terminal blocks mounted on the rail. The terminal block relay may provide a plurality of terminals accessible at upper and lower edges of the terminal block relay for receiving electrical connectors communicating electrical signals to a relay of the terminal block relay.
The fuse adapter comprises an insulating housing supporting a fuse holder within the housing. The fuse holder has a first and second socket receiving corresponding ends of a standard electrical fuse.
The fuse
64
may be replaced by prying it away from the sockets
60
and
66
, which provide a spring clamping through their metallic elements.
A conductive extension is connected at a first end within the housing to the first socket. A second end of the conductive extension extends from the housing in an engagement direction so that it may be received and retained by a terminal of the terminal block relay. A wire terminal is supported by the housing and attached to the second socket so that it may receive and retain an external electrical conductor of a type normally received by the terminals of the terminal block relay. When the conductive extension is retained by a terminal of the terminal block relay, the housing lies substantially between planes of the left and right planar walls of the terminal block relay.
Thus, it is one object of the invention to provide a method of adding a fuse to a terminal block relay without using additional space along the mounting rail.
It is yet another object of the invention to provide a method of adding a fuse to a terminal block relay that reduces the number of terminal connections that must be made and eliminates a jumper. The present invention requires only two terminal attachments compared to three terminal attachments required when a jumper is used between a terminal block fuse and a terminal block relay.
It is yet another object of the invention to provide a convenient system for isolating outputs of programmable logic controllers using fuses and relays.
When the conductive extension is attached to a conventional terminal block relay, the left and right walls of the housing of the in-plane fuse adapter may be co-planar with the left and right planar walls of the terminal block relay.
Thus, it is another object of the invention to provide an assembled unit that retains substantially planar left and right walls minimizing areas that could catch debris or interfere with wiring operations.
The housing of the fuse adapter may include at least two retention surfaces that are not parallel to each other and that abut corresponding surfaces of the terminal block relay to resist torsion of the fuse adapter when it is installed in the terminal block relay. Alternatively or in addition, the housing of the fuse adapter may include a key portion fitting within a corresponding keyway of the terminal block relay to resist torsion of the fuse adapter with respect to the terminal block relay.
Thus, it is an object of the invention to provide a fuse adapter providing improved mechanical termination of a connecting wire.
The wire terminal may be positioned in the housing of the fuse adapter to receive an external electrical conductor along the engagement direction.
Thus, it is another object of the invention to allow wiring of the terminal block along the same axis and in a manner similar to that which would be used without the fuse adapter.
The wire terminal may operate to releasably retain the electrical conductor and in one embodiment, may be a screw and clamp terminal.
Thus, it is another object of the invention to preserve the benefits of being able to rewire the terminal block relay.
The extension may include a surface embossment.
It is therefore another object of the invention to provide increased mechanical retention of the fuse adapter as well as electrical connection.
The housing of the fuse adapter may include a door, or a hinged lever, providing access to the fuse holder.
It is thus another object of the invention to allow the fuse to be replaced without affecting the mechanical integrity of the connection between the wire and the terminal block relay.
The first and second socket of the fuse holder may be opposed about an access perpendicular to the extension direction and parallel to the left and right planar wall of the terminal block relay when the conductive extension is retained by a terminal of the terminal block relay.
Thus, it is another object of the invention to accommodate standard glass fuses without unduly increasing the cantilever of the fuse adapter.
The substantially constant lateral thickness of the terminal block is in most cases 6.2 mm.
Thus, it is another object of the invention to provide a system that works with standard European-type terminal blocks.
The fuse adapter may include an indicator lamp connected electrically in parallel with the sockets to light when the fuse is absent or open. The lamp may be an LED or neon and may be exposed through the housing along a front edge of the housing away from the rail when the conductive extension is retained by a terminal of the terminal block relay.
Thus, it is another object of the invention to provide a fuse adapter that provides features normally found in a terminal block fuse.
These particular objects and advantages may apply to only some embodiments falling within the claims and thus do not define the scope of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is a perspective view of a standard terminal block relay mounted at its rear on a DIN rail (inverted from normal mounting to show the latching mechanism) with the fuse adapter of the present invention attached at a lower edge;
FIG. 2
is an exploded view of the fuse adapter and terminal block relay of
FIG. 1
rotated by 90 degrees and in partial cross-section showing a conductive extension of the fuse adapter received by a screw terminal of the terminal block relay to provide mechanical and electrical connection to the terminal block relay, and showing a screw terminal, internal fuse, and indicator lamp of the fuse adapter;
FIG. 3
is a perspective view of the fuse adapter of
FIG. 2
showing the orientation of the fuse in phantom and the opening of a door for replacing the fuse without mechanical disconnection of an external wire; and
FIG. 4
is a fragmentary, side elevational view of the terminal block relay of
FIG. 1
(inverted with respect to
FIG. 1
) with the fuse adapter attached to terminal of the terminal block relay and showing the abutment of two surfaces of the fuse adapter to resist torsion and further showing the use of a key received in a keyway of the fuse adapter to provide increased mechanical stability and showing the forward facing screw terminal and indicator lamp.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to
FIG. 1
, a standard terminal block relay
10
may include a rear surface
12
having a channel
14
for receiving a DIN rail
16
. Left side
20
and right sides
22
of the terminal block relay
10
are substantially planar so as to abut corresponding left or right sides of other similar terminal blocks that may also be placed on the DIN rail
16
and stacked together against the terminal block relay
10
with no wasted space. The terminal block relay
10
may be releasably retained on the DIN rail
16
by operation of a catch (not shown) retractable by a slide
18
.
The upper and lower edges of the terminal block relay
10
support terminals
24
, such as screw terminals, for receiving and electrically connecting to wires
26
, free from interference from adjacent terminal blocks.
The front edge
32
of the terminal block relay
10
includes a socket
34
holding a narrow profile electrical relay
36
whose left and right sides are coplanar with left side
20
and right side
22
of the terminal block relay
10
, and whose front edge is flush with the front edge
32
of the terminal block relay
10
, the relay
36
may be removed from the terminal block relay
10
for repair or to change the relay type as may be desired.
As is understood in the art, contacts and coil of the relay
36
are connected through the socket
34
to the various ones of the terminals
24
via conductors internal to the terminal block relay
10
. The terminal block relay
10
thus providing a simple method of connecting to the relay
36
mechanically and electrically.
Terminal block relays
10
of this kind ,may be commercially purchased from a variety of vendors including the Allen-Bradley brand from Rockwell Automation of Milwaukee, Wis.
According to the present invention, a fuse adapter
40
may be attached at one of the terminals
24
of the terminal block relay
10
. Generally, the fuse adapter
40
allows a fuse to be incorporated into the circuit of the relay
36
of the terminal block relay
10
so that a first external wire
26
from a line source L
1
(possibly connected through shutoff switches and the like), may connect to one side of the terminal block relay
10
and, via internal conductors, to a contact of the relay
36
. A return from the contact of the relay
36
may pass through other internal conductors to a terminal
24
of the terminal block relay
10
and then through the fuse adapter
40
containing a fuse (not shown). From the fuse adapter
40
, the conductive path may proceed to an inductive load
47
to return to the remaining side of the line L
2
.
Referring now to
FIGS. 1 and 2
, the fuse adapter
40
may have a generally block-shaped outer housing
42
molded of an electrically nonconductive plastic. The housing
42
provides left and right sides
43
and
44
that are coplanar with left side
20
and right side
22
of the terminal block relay
10
when the fuse adapter
40
is attached to the terminal block relay
10
.
Joining the left and right sides
43
and
44
of the housing
42
are opposed terminal wall
44
and conductive extension wall
46
, and opposed front and rear wall
48
and
50
, respectively, each named according to the orientation of the fuse adapter
40
when it is engaged with the terminal block relay
10
.
Passing out of the extension wall
46
is a conductive extension
52
that may be received by terminal
24
of the terminal block relay
10
. Specifically, the conductive extension
52
fits into a stirrup
56
of the terminal
24
and is pulled against an internal conductor
54
by one wall of the stirrup
56
which compresses the extension
52
against the internal conductor
54
driven by action of a captive screw
30
. Such screw terminals
24
are well known in the art.
The conductive extension
52
as held by the extension wall
46
also extends into the housing
42
of the fuse adapter
40
to connect to a first socket
60
positioned near the rear wall
50
. Socket
60
provides a spring clamp sized to receive one end cap
62
of a standard electrical fuse
64
. Positioned within the opposite side of the housing
42
near front wall
48
of the housing is a second socket
66
for receiving the second end cap
68
of the fuse
64
. The fuse
64
is thus held along an axis extending generally from the front to the back of the terminal block relay
10
when the fuse adapter
40
is installed.
The socket
66
connects to internal conductor
70
which is received within a stirrup
72
of a terminal
74
similar to terminal
24
. A screw
76
, accessible through the front wall
48
of the housing
42
, may tighten the stirrup
72
to compress the internal conductor
70
into electrical contact with an external wire
26
inserted into the stirrup
72
. Alternatively, a screwless type clamp, well known in the art, may be used
A front facing indicator lamp
82
, preferably a light emitting diode (LED) or neon lamp, is connected in parallel across sockets
66
and
60
with one lead of the lamp
82
connecting through resistor
84
to socket
60
and a second lead connecting directly to socket
66
. When the fuse
64
is absent or open, the application of a voltage across the extension
52
and terminal
74
will cause the lamp
82
to light indicating the fuse
64
needs to be replaced. Such a circuit is adequate for low voltage AC and DC applications and may be modified as is understood in the art for higher voltage applications or polarity sensitive applications.
In the preferred embodiment, an insertion direction
85
along which the external wire
26
is inserted into the terminal
74
will be the same as the insertion direction along which the extension
52
is inserted into the terminal
24
. In addition, the screw
76
is accessible by a screwdriver
90
in the same direction as the screws
30
of the other terminals (as shown in FIGS.
2
and
4
). In this way, the orientation of external wiring is not significantly altered when the fuse adapter
40
is added.
Referring now to
FIG. 3
, the housing
42
may include a door
86
that may hinge to an open position (shown in phantom) to allow access to the fuse
64
for replacement. The door may be hinged by means of a living hinge formed in the plastic of the housing
42
. As will be understood, the orientation of the fuse
64
allows the height of the fuse adapter
40
measured away from the terminal block relay
10
to be minimized reducing torque on the extension
52
. The surface of the extension
52
such as engages the stirrup
56
and/or the internal conductor
54
of terminal
24
of the terminal block relay
10
may include a series of sharpened ridges
53
or embossment to present slippage between these surfaces.
Referring now to
FIG. 4
, preferably, the wire
26
is attached to the fuse adapter
40
before the fuse adapter
40
is attached to the terminal block relay
10
. In this way, any twisting by screwdriver
90
on the housing
42
is not transmitted to the connection between the fuse adapter
40
and the terminal block relay
10
.
Twisting of the fuse adapter
40
caused by the external wire
26
may be absorbed by the abutment of surfaces of the housing
42
of the fuse adapter
40
and the housing of the terminal block relay
10
. Preferably, at least two perpendicular surfaces, for example, the conductive extension wall
46
and the rear wall
50
of the fuse adapter
40
may abut corresponding surfaces on the terminal block relay
10
. The extension
52
holds these surfaces tightly against the terminal block relay
10
allowing these abutting surfaces to convert torque to the housing
42
to tension on the conductive extension
52
which is more readily accommodated by the terminal
24
.
The housing
42
of the fuse adapter
40
may further include a key section
92
interfitting within a keyway
94
such as may be intentionally added to the terminal block relay
10
or may be fortuitously existing for other purposes, in this case, for a jumper connector channel. The housing
42
may also include a post on the rear surface interfitting with the opening of the terminal block relay screw terminal below.
It is specifically intended that the present invention not be limited to the embodiments and illustrations contained herein, but include modified forms of those embodiments including portions of the embodiments and combinations of elements of different embodiments as come within the scope of the following claims.
Claims
- 1. An in-plane fuse adapter used with a terminal block relay of a type mountable at a rear surface on a laterally extending rail to present a substantially constant lateral thickness between left and right planar walls that may abut corresponding planar walls of adjacent terminal blocks mounted on the rail, the terminal block relay further providing a plurality of terminals accessible at upper and lower edges of the terminal block relay for receiving electrical conductors communicating electrical signals to a relay of the terminal block relay, the fuse adapter comprising:an insulating housing; a fuse holder within the insulating housing having a first and second socket receiving corresponding ends of a standard electrical fuse; a conductive extension having a first end within the housing attached to the first socket, and a second end extending from the housing in an engagement direction to be received and retained by a terminal of the terminal block relay; and a wire terminal held by the housing and attached to the second socket positioned to receive and retain an external electrical conductor of a type normally received by the plurality of terminals of the terminal block relay; wherein when the conductive extension is retained by a terminal of the terminal block relay, the housing lies substantially between planes of the left and right planar walls of the terminal block relay.
- 2. The in-plane fuse adapter of claim 1 wherein when the conductive extension is retained by the terminal of the terminal block relay, the fuse adapter has left and right planar walls that are co-planar with the left and right planar walls, respectively, of the terminal block relay.
- 3. The in-plane fuse adapter of claim 1 wherein the housing includes at least two surfaces that are not parallel to each other and that abut corresponding surfaces of the terminal block relay to resist torsion of the fuse adapter with respect to the terminal block relay when the conductive extension is retained by the terminal of the terminal block relay.
- 4. The in-plane fuse adapter of claim 1 wherein the housing includes a key portion fitting within a corresponding keyway on the terminal block relay to resist torsion of the fuse adapter with respect to the terminal block relay.
- 5. The in-plane fuse adapter of claim 1 wherein the wire terminal is positioned within the housing to receive the external electrical conductor along the engagement direction.
- 6. The in-plane fuse adapter of claim 1 wherein the wire terminal operates to releasably retain the electrical conductor.
- 7. The in-plane fuse adapter of claim 1 wherein the wire terminal is selected from the group consisting of :a screw and clamp terminal and a screwless clamp.
- 8. The in-plane fuse adapter of claim 1 wherein the extension includes surface embossments to resist slippage of the extension when retained by the terminal of the terminal block relay.
- 9. The in-plane fuse adapter of claim 1 wherein the housing includes an opening providing access to the fuse holder.
- 10. The in-plane fuse adapter of claim 1 wherein the first and second socket are opposed about an axis perpendicular (or at an angle) to the extension direction and parallel to the left and right planar walls of the terminal block relay when the conductive extension is retained by a terminal of the terminal block relay.
- 11. The in-plane fuse adapter of claim 1 wherein the substantially constant lateral thickness is substantially from 5 to 8 mm.
- 12. The in-plane fuse adapter of claim 1 further including an indicator lamp connected electrically in parallel with the sockets to light when the fuse is absent or open.
- 13. The in-plane fuse adapter of claim 12 wherein the indicator lamp is selected from the group consisting of a light emitting diode and a neon lamp.
- 14. The in-plane fuse adapter of claim 12 wherein the lamp is exposed through the housing along a front edge of the housing opposite to the rail when the conductive extension is retained by the terminal of the terminal block relay.
- 15. A terminal block relay comprising:a housing having a rear surface including a channel allowing the housing to be mounted on a laterally extending rail to present a substantially constant lateral thickness between left and right planar walls that may abut corresponding planar walls of adjacent terminal blocks mounted on the rail; a plurality of terminals accessible at upper and lower edges of the terminal block relay for receiving electrical conductors communicating electrical signals to a relay of the terminal block relay; an in-plane fuse adapter including: (a) an insulating housing; (b) a fuse holder within the insulating housing having a first and second socket receiving corresponding ends of a standard electrical fuse; (c) a conductive extension having a first end within the housing attached to the first socket and a second end extending from the housing in an engagement direction to be received and retained by a terminal of the terminal block relay; and (d) a wire terminal held by the housing and attached to the second socket positioned to receive and retain an external electrical conductor of a type normally received by the plurality of terminals of the terminal block relay; wherein when the conductive extension is retained by a terminal of the terminal block relay, the housing lies substantially between planes of the left and right planar walls of the terminal block relay.
US Referenced Citations (3)
Number |
Name |
Date |
Kind |
4968269 |
Urani et al. |
Nov 1990 |
A |
5515023 |
Marach et al. |
May 1996 |
A |
5616054 |
Quinlan |
Apr 1997 |
A |