Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates to instrument panel assemblies and in
particular to means for permitting selective testing of the operability
of the indicating means thereof.
In instrument panel assemblies of the prior art7 a plurality
of indicating lamps or the like may be mounted to a panel for indicating
different conditions of associated equipment. Illustratively~ in a
vehicle, the instrument panel may include a plurality of indicating lamps
arranged to indicate abnormal conditions, such as high oil temperature, etc.
In the commercial automobile field, such indicator lamps are
considered to be somewhat unreliable relative to protecting the associated
equipment in that a burnout or loose connection of the particular indicator
lamp causes a failure of indication to the driver of a malfunction of the
apparatus of the vehicle. Illustratively, where the indicator lamp
provided to signal a low oil level condition burns out, the driver of the
vehicle may not be properly apprised of such condition, causing serious
and costly damage to the engine.
The present invention comprehends the provision in such an
instrument panel assembly of an improved means for facilitated testing of
the indicator means of the instrument panel.
According to one aspect of the invention, there is provided a
vehicle fitted with an instrument panel assembly, the assembly having a
plurality of electrical indicator lamps mounted in a display panel to be
replaceable forwardly thereof and viewable from forwardly thereof, an
electrical power source, means connecting the lamps in parallel to one
terminal of the power source, and control switches each connected in
series with a respective one of the lamps and in parallel to the opposite
terminal of the power source; wherein a lamp testing circuit comprises
a normally open test switch connected to the opposite terminal; and a
plurality of diodes each connected to a point between a respective
connected lamp and control switch and through the test switch to the
opposite terminal and, mounted to a carrier removably carried rearwardly
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on the display panel, all of the diodes he:ing arranged to permit current
flow in the same d:irection relative to the test switch whereby closing of
the test switch causes concurrent energization of each operati.ve lamp.
According to another aspect of the invention, there is provided ;~
a vehicle fitted with an instrument panel assembly having a display panel
having a vertical portion carrying first instrumentation and a plurality
of electrical indicator lamps adjacent said first instrumentation, said
panel further having a downwardly facing portion spaced from said vertical
portion, an electrical power source having first and second terminals, means
connected the lamps in parallel to said first terminal of the power source,
and control switches connected one each in series with the respective lamps
and in parallel to said second terminal of the power source for providing
selective energization of said lamps from said power source, an improved
lamp testing circuit comprising: a normally open manually operable test
switch carried by said panel downwardly facing portion in adjacent spaced
relation to said indicator lamps, said switch being electrically connected
to said second terminal; lenses covering said lamps on said panel, said . ?
lenses being removable from forwardly of the panel to permit replacement of ~ :
each lamp from forwardly of said panel; and a plurality of diodes carried
on the rear of said panel in rearwardly spaced relation to said indicator
lamps, said diodes being electrically connected one each to between the ~
respective connected lamps and control switches and through said test ~ ;:
switch ~co said second terminal, all of said diodes being arranged to permit
current flow in the same direction relative ~o said test switch, whereby .
closing of the test switch causes concurrent energization of each operative ;
lamp from said power source, said test switch having a moving contact
connected solely to said second terminal and a fixed contact connected .
solely to said diodes whereby closing of said switch makes an electrical
connection from said second terminal solely to said diodes thereby
effectively positively providing an indication of the operative condition
of each lamp. '~ ;~
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Other features and advantages of the invention will be
apparent from the following description taken in connection with the
accompanying drawing wherein:
FIGURE 1 is a side elevation of a vehicle in which an instru-
ment panel assembly of the present invention may be installed;
FIGURE 2 is a front elevation of the instru~ent panel;
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FIGURE 3 is a vertical section taken substantially
along the line 3-3 of Figure 2;
FIGURE 4 is a schematic wiring diagram illustrating the
improved lamp testing circuit of the instrument panel assembly; and
FIGURE 5 is a fragmentary schematic wiring diagram
illustrating the use of a battery as the power source.
DESCRIPTION OF TE E PREFERRED EMBODIMENT
In the exemplary embodiment of the invention as dis-
closed in the drawing, an instrument panel generally designated
lO is adapted for use in a vehicle, such as a loader, generally
designated 11, and more specifically may be arranged to be
mounted in the cab 12 thereof adjacent the steering wheel 13
for monitoring of the vehicle components by the driver when the `
vehicle is in use. Such instrument panels conventionally in- ~;
clude a plurality of indicators 14 having a corresponding plur-
ality of indicator lamps 15 which are selectively illuminated ~-
such as for indicating malfunctioning or other conditions of
the vehicle components. ~-
The instrument panels may include other instrumenta-
tion, such as instrumentation 16 shown in Figure 2. The presentinvention, however, is directed to an improved means for testing
the lamps 15 of the indicators 14 to effectively avoid a failure
of indication as by a burnout or malfunction of the indicator
lamps.
Referring now to Figures 3 and 4, instrument panel 10
comprises an assembly having a front panel portion 17 through
which indica$or lamps 15 may be selectively viewed. The indi- ~,
cator lamps are connected in a circuit generally designated 18
and are arranged to be energized therein from a power source,
which illustratively may include a transformer l9 which may have
a low voltage secondary 20 connected at one end to ground 21.
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The other end of transformer secondary 20 may be connected
to each of the indicator lamps 15 so as to provide a parallel
connection therebetween. Each of the indicator lamps, in turn,
may be controlled by a suitable normally open switch 22 con-
nected between the respective lamps 15 and ground 21.
A test circuit generally designated 23 for testing
the lamps 15 when desired by the user, includes a normally open
switch 24 having its moving contact 24a connected to ground 21
and its fixed contact 24b connected to a parallel arrangement
of a plurality of diodes 25 connected one each to between the
respective indicator lamps 15 and control switches 22. Two ;
such lamps and associated control diodes are showng it being
understood that the invention comprehends the provision of any
number of such lamp and diode combinations in parallel.
More specifically, each lamp 15 is connected to its `~
associated control switch by a connection 26. Diodes 25 are ~
connected one each to the respective connections 26 so as to ;
be connected in series one each with the respective lamps. The
diodes, in turn, are connected to a common connection 27 to
which fixed contact 24b of switch 24 is connected.
As shown in Figure 5, the power supply to control
circuit 18 may comprise a direct current power supply, such as
a conventional battery 28 connected between ground 21 and the
common connection 29 to each of the indicator lamps 15.
As shown in Figure 3, diodes 25 may be mounted on a
panel 30 carried on the rear of instrument panel 17.
When it is desired to test the operability OI' the
indicator lamps 15, the user need merely close control switch
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24, which, as shown in ~igure 2, may be provided with a manual
actuator 31, disposed for facilitated selective manipulation
by the user such as at a lower portion 32 of the instrument
panel 10. Closing of switch 24 completes a circuit through
each of the operable lamps 15 and diodes 25, through the
switch to ground 21. Thus, each operable lamp 15 is concur-
rently energized so as to provide an immediate indication to
the user of the operability of the lamps. Any lamp which is
not so illuminated upon the closing of switch 24 may be
readily replaced by the removal of the lens 33 of the indi-
cator 14 with which the defective lamp is associated, from
forwardly of the instrument panel 10. In the event the re~ ;
placement of the bulb does not effect illumination thereof upon
retesting of the circuit by reclosing switch 24, the user is
apprised of a malfunctioning of that particular portion of
the control circuit 18 so that suitable servicing can be
effected to remedy the defect.
Diodes 25 prevent spurious parallel operation of the
lamps as by the closing of any one single control switch 22 as
20 a result of the parallel connection of each of the lamps to
the single test switch 24. Thus, each of the diodes 25 broadly
comprehends a unidirectional current element which prevents back-
feed from one lamp 15 circuit to another lamp 15 circuit while
yet permitting facilitated rapid testing of the individual lamps
by one single pole, normally open switch.
Thus, the instrument panel assembly test means is extremely -~
simple and economical of construction while yet providing an i~
improved rapid testing of the indicating lamps of the instrument `
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panel, thereby avoiding the serlous problem of failure of the individual
lamps to prpperly indicate a malfunction of the vehlcle component because
of a burnout or other inoperable condition of the particular lamp
circuit portion. ~
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