Liquid level sensor, pump system means and circuit means

A plurality of probes are situated as to experience being touched by the liquid being monitored; when at least one of such probes is touched by the liquid related electrical circuit means becomes energized as to cause related pumping means to be activated thereby pumping some of the monitored liquid to, in turn, reduce the level of such monitored liquid; when the level of the monitored liquid decreases to a predetermined level, the pumping means is automatically de-activated; during periods wherein there might occur a momentary splashing or sloshing of the monitored liquid, time delay means serves to correspondingly delay activation of said pumping means thereby preventing unnecessary activation of the pumping means.

BACKGROUND OF THE INVENTION 
Generally, the invention relates to the monitoring of liquid levels and to 
the automatic pumping of such liquid levels as to thereby, generally, be 
capable of maintaining the level of such monitored liquid below a 
preselected maximum level, or when considered from yet another point of 
view, maintaining the level of such monitored liquid within a preselected 
range of levels. As will become apparent, even though the invention was 
first conceived in the course of desiring to solve the prior art problems 
as relate to boat and/or ship bilge pumping systems, the invention, as 
conceived, and as hereinafter more fully disclosed has applications to 
fields other than such bilge pumping systems. However, to better 
appreciate the significance of the invention, the background of the 
invention will be set forth as it applies to the heretofore prior art 
proposed bilge pumping systems. 
As is well known and recognized, almost without exception, water craft 
and/or vehicles, for varying reasons, accumulate liquids in the bilge 
area. In some cases such liquid may be water while in other cases the 
bilge liquid may even be comprised of oil, gasoline or other substances, 
singly or in any combination, which may also be mixed with water. Often, 
such bilges also contain various bits of debris which may or may not float 
in the liquid but which is, nevertheless, movable therewithin. 
Further, since the bilge is generally at the lower part of the hull (or 
body) of the water craft and since hulls are somewhat streamlined or 
otherwise non-uniform longitudinally along the keel, it is apparent that, 
for example, the same level of liquid along the length of the hull does 
not denote the same unit of volume of such liquid if measured at regular 
intervals longitudinally along the hull. In other words, the hull may be 
considered as a vessel of irregular configuration containing therein the 
bilge liquid. Consequently, if the hull is at rest and not moving with 
respect to the water, the level of the bilge liquid may be at a first 
elevation and span the entire distance from the stem to the stern; 
however, if the hull is then somewhat tilted as to have, for example, the 
stem or prow become relatively elevated, the level and relative attitude 
of that same quantity of bilge liquid will change and, quite possibly, 
will no longer span the entire distance from stem to stern. 
Further, during operation of the water craft, the bilge liquid often 
undergoes sloshing due to, for example, the water craft executing turns or 
experiencing waves. This, in turn, causes the surface of the bilge liquid 
to rapidly and randomly change in configuration and relative location. 
Heretofore, the prior art bilge pumping systems, which were considered to 
be automatic, employed such devices as float members to sense, by buoyant 
displacement, the presence of bilge liquid. Such float members, in turn, 
were employed to open and close related electrical switch means in order 
to thereby deenergize and energize electrical motors means for driving 
related pump means. However, as should be apparent, the prior art float 
members were totally responsive to level of the bilge liquid even if that 
level was momentary or a false indication of the actual quantity of bilge 
liquid carried by the water craft. That is, if the relative level and 
attitude of the bilge liquid was changed for a short period of time, as 
during turns, etc., the prior art float would respond to the resulting 
presence or absence of the bilge liquid and accordingly activate or 
de-activate the pumping means. The same situation would occur when the 
bilge liquid experienced sloshing. 
Also, as the water craft experienced water or wave pounding and reacted as 
by rolling or pitching, the prior art float members would also become 
unstable, due to inherent inertia, again resulting in undesired activation 
and de-activation of relating pumping means. 
The prior art floats were often associated with related moving linkage 
means in order that relative motion of the float could be sensed as to 
thereby activate and de-activate associated pumping means. This raisd 
other problems associated with dirt and corrosion which often prevented 
such linkage means from having the freedom of relative motion necessary to 
permit the float to move in response to changes in level of the bilge 
liquid. 
Accordingly, the invention as herein disclosed is primarily directed to the 
solution of the foregoing as well as other related and attendant problems 
whether in the art of bilge pumping systems or in other applications of 
pumping and/or liquid level sensing systems. 
SUMMARY OF THE INVENTION 
According to the invention, a liquid pumping system comprises at least one 
electrical probe means, electrical circuit means associated with said 
probe means, and liquid pumping means, said probe means being effective 
when in the presence of said liquid to generate related electrical signal 
means, said electrical circuit means being effective to in turn create an 
electrical output in response to said electrical signal means, and said 
liquid pumping means being activated in response to said electrical output 
in order to thereby pump said liquid from a first area to a second 
discharge area. 
Various general and specific objects, advantages and aspects of the 
invention will become apparent when reference is made to the following 
detailed description considered in conjunction with the accompanying 
drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now in greater detail to the drawings, FIG. 1, in simplified 
form, illustrates, in generally longitudinal cross-section, a boat or 
water craft 10 having a hull 12 with a prow or stem 14 and stern 16 along 
with related decking 18. The bilge area 20 is shown as containing bilge 
liquid 22. Suitable liquid pumping means 24, carried as within the hull 
12, has an intake or inlet conduit means 26 and an outlet or discharge 
conduit means 28. Intake conduit 26 may extend, as generally depicted, to 
any desired area within the bilge and be situated as to be quickly 
submerged as by the accumulation of even a relatively slight amount of 
bilge liquid. Further, if desired, the intake end of inlet conduit means 
26 may be provided with suitable screen or filter means as to thereby 
guard against foreign matter becoming lodged therewithin. 
Suitable suppport or platform means 30 serves to support electrical control 
means 32 while support member 34 and 36 respectively hold probes 38 and 40 
at preselected elevations. Related sensory signal or warning means 42, 
carried as on instrument panel means 44, serves to provide desired sensory 
signals to the water craft operator. 
Referring to FIG. 2, the electrical circuitry 32 is illustrated as 
comprising a plurality of C-MOS type integrated circuit NAND gates 46, 48, 
50, 52, 54, 56, 58 and 60. The output terminal 62 of gate 46 is 
electrically connected via conductor means 64 to both input terminals 66 
and 68 of gate 46; the output terminal 70 of gate 48 is connected as via 
conductor means 72, 74 and 76, series resistor means 78 and diode means 
80, and branch conductors 82 and 84 to both input terminals 86 and 88 of 
gate 50. 
Conductor means 90 comprising series resistance means 92 serves to 
electrically connect output terminal 94 of gate 50 with input terminal 96 
of gate 52. A diode 98 is placed electrically in parallel with resistance 
92. Gate 52, in turn, has its output terminal 100 electrically connected 
to input terminal 102 of gate 54 as by conductor means 104. 
Conductor means 106, 108 and 110 along with series resistance means 112 and 
diode means 114 as well as branch conductor means 116 and 118 serve to 
electrically interconnect both input terminals 120 and 122 of gate 56 to 
conductor 72 and the output terminal 70 of gate 48. 
The output terminal 124 of gate 56 is electrically connected via conductor 
means 126 and series resistance means 128 to an input terminal 130 of gate 
58. A diode 132 is placed in parallel with resistance 128. Output terminal 
124 is also electrically connected as by conductor means 134 to the second 
input terminal 136 of gate 52. 
Conductor means 138 serves to electrically connect the output terminal 140 
of gate 58 to the second input terminal 142 of gate 54. Similarly, the 
output terminal 144 of gate 54 is electrically connected to the second 
input terminal 146 of gate 58 as by conductor means 148 electrically 
connected to terminal 146 as through conductor means 150 and resistance 
means 151 leading to a Darlington circuit 152. 
The output terminal 140 of gate 58 is also electrically connected as 
through conductor means 138, 154, series resistance 156, conductor 158 and 
branch conductors 160 and 162 to both input terminals 164 and 166 of gate 
60. A diode 168 is placed electrically in parallel to resistance 156. 
The output terminal 170 of gate 60 is connected as by conductor means 172 
and series resistance means 174 to a second Darlington circuit 176. As 
illustrated, the Darlington circuit 152 comprises a first NPN transistor 
178 which has its base electrode 180 electrically connected to the other 
end of resistor 151 while its emitter 182 is connected to the base 183 of 
a second NPN transistor 184. The emitter 186 of transistor 184 is 
connected to ground 188 as by conductor means 190 while the collector 192 
is connected as by conductor means 194 to the field winding 196 of an 
associated relay assembly 198 comprising openable and closeable electrical 
contacts 200 and 202 responsive to the energization and de-energization of 
winding 196. The collector 204 of transistor 178 is also connected to 
conductor means 194 and collector 192, while a zener diode 206 is placed 
in parallel with the emitter-collector circuit of transistor 184. 
Similarly, Darlington circuit 176 comprises a first NPN transistor 208 
which has its base electrode 210 electrically connected to the other end 
of resistance 174 while its emitter 212 is connected to the base 214 of a 
second NPN transistor 216. The emitter 218 of transistor 216 is connected 
to ground 219 as via conductor means 220 while the collector 222 is 
connected as by conductor means 224 to associated output or sensory signal 
producing means 226 which may be, in turn, electrically connected to 
conductor means 294 as by conductor means 228. The collector 230 of 
transistor 208 is also connected to conductor means 224 and to collector 
222 of transistor 216 while a zener diode 232 is placed in parallel with 
and across the emitter-collector circuit of transistor 216. 
The upper or higher elevation probe 40 is electrically connected as through 
conductor means 234 to conductor means 74 as at a point generally between 
resistance 78 and diode 80. Further, resistance means 240 is placed 
generally in parallel with diode 80. 
The lower or lesser elevation probe 38 is electrically connected as through 
conductor means 242 to conductor means 108 as at a point generally between 
resistance 112 and diode 114. Further, resistance means 246 is placed 
generally in parallel with diode 114. 
Capacitor means are provided as at 248, 250, 252 and 254 respectively 
grounded as at 256, 258, 260 and 262. The other electrical sides of such 
capacitors are respectively electrically connected to conductor means 76, 
90, 110 and 126. If it should be desired, further capacitor means may be 
provided as at 264 and 266, respectively grounded as at 268 and 270 and 
having their other electrical sides respectively electrically connected to 
conductor means 104, as generally between output terminal 100 and input 
terminal 102, and conductor means 126, as generally between where 
capacitor 254 is connected and input terminal 130. 
A suitable source of electrical potential 272, grounded as at 274, has its 
other terminal electricaly connected to conductor means 280, in turn, 
connected means 282 leading to relay contact 200 and conductor means 284 
leading to a diode 286. 
A resistor 288 is connected in series with diode 286 and a zener diode 290 
which, in turn, is grounded as at 292. Conductor means 294, electrically 
connected to resistor 288 as at a point generally between diode 286 and 
resistor 288 is connected to the other end of relay field winding 196 
while a second conductor 296 electrically connected as at a point 
generally between resistor 288 and zener diode 290 is electrically 
connected to gates 46 and 52 as at respective terminals 298 and 300 as by 
conductor portions 299 and 301. Gates 46 and 52 have their respective 
other terminals 302 and 304 connected to ground as at 306 and 308. In the 
embodiment shown, gates 46, 48, 50 and 56 may comprise a first quad-chip 
and, therefore, the logic power may be supplied to all through one 
connection as depicted with respect to gate 46. Similarly, gates 52, 54, 
58 and 60 may also comprise a second quad-chip and, therefore, the logic 
power may be supplied to all through one connection as depicted with 
respect to gate 52. 
A capacitor 310 has its one electrical side electrically connected to 
conductor 158 while its other electrical side is connected to conductor 
296 as via conductor means 312. 
With reference to gates 46 and 48, it can be seen that through branch 
conductor means 314 and 316, both input terminals 318 and 320 of gate 48 
are electrically connected to conductor means 322 which, in turn, is 
electrically connected to one side of capacitor means 324 the other 
electrical side of which is electrically connected to conductor means 106 
and, therethrough, to output terminal 70 of gate 48. A resistor 326 has 
one end connected to conductor 322 while its other end is connected to 
conductor 64. A capacitor 328, grounded as at 330, is preferably connected 
to conductor means 296 to filter any electrical noise therein. Also, as 
can be seen, relay contact 202 is electrically connected as by conductor 
means 332 as to motor-pump assembly 24 which may be grounded as at 334. 
General Operation of Invention 
As should be apparent, diode 286, resistance 288, zener 290 and capacitor 
328 comprise a regulated power supply means with, of course, the voltage 
on conductor means 294 being relatively greater than the voltage on 
conductor means 296. 
Gates 46, 48, 50 and 56 both amplify and invert. Further, gates 46 and 48 
along with resistance 326 and capacitor 324 comprise and function as 
oscillator means having an output, at terminal 70 of gate 48, of fixed 
frequency. The output from terminal 70 is fed through resistor 78 and 
conductor 234 to probe 40 as well as though conductor 106, resistor 112 
and conductor 242 to probe 38. Further, probe 40, generally, acts as a 
voltage divider in conjunction with resistance 78. Resistor 240, diode 80 
and capacitor 248 combine to function as detector means 340. That is, when 
probe 40 is out of the bilge liquid, it creates, effectively, what can be 
thought of as a relatively high resistance causing the detector means to 
provide an "on" signal resulting in input terminals 86 and 88 of gate 50 
having applied thereto a "high" signal. Similarly, when probe 38 is out of 
the bilge liquid, it, too, creates what can be thought of as a relatively 
high resistance causing the associated detector means 342, comprised of 
resistor 112, diode 114 and capacitor 244, to provide an "on" signal 
resulting in input terminals 120 and 122 of gate 56 having applied thereto 
a "high" signal. Whenever the input signals on both inputs 86 and 88 are 
"high", the signal at the output 94 of gate 50 is "low"; likewise, when 
the input signals on both inputs 120 and 122 are "high", the signal at the 
output 124 of gate 56 is "low". Consequently, it can be seen that in the 
logic of the circuitry gates 50 and 56 act as amplifying inverters and 
provide no NAND gate function at all. 
Now, let it be assumed that both probes 40 and 38 are immersed in the bilge 
liquid. As a consequence of this the relative apparent resistance of 
probes 40 and 38 diminish to a point that such appear as respective short 
circuits to detector means 340 and 342. As a result thereof, the input 
signals on input terminals 86 and 88 of gate 50 go "low" and, likewise, 
the signals on input terminals 120 and 122 of gate 56 go "low". Since 
gates 50 and 56 invert, the output signals on each of the respective 
output terminals 94 and 124 then become "high". 
As can be seen, the outputs of gates 50 and 56 are applied to the 
respective input terminals 96 and 136 of NAND gate 52 and, since each of 
such input signals is "high" the inverting function of gate 52 causes its 
output at terminal 100 to go "low" which, in turn, causes the signal at 
input terminal 102 of NAND gate 54 to also be "low". At the same time, the 
"high" output signal from gate 56 is applied to the input terminal 130 of 
NAND gate 58. Consequently, the output at terminal 140 of gate 58 becomes 
"low" and such is applied to the input 142 of NAND gate 54. With both 
inputs 102 and 142 of gate 54 being "low", the gate 54 is turned on and 
the signal at the output 144 becomes "high". As should be noted, the 
"high" output on conductor 150 is fed back to input terminal 146 of NAND 
gate 58 which becomes a latching arrangement in that now both inputs 146 
and 130 of gate 58 are maintained at a "high" signal, thereby maintaining 
gate 54 on, for as long as the lower probe 38 is engaged with the bilge 
liquid. 
The thusly established "high" output signal from output 144 is applied to 
the base-emitter diode of transistor 178 causing such to be turned on, or 
made conductive, and, in turn, causing transistor 184 to be likewise made 
conductive. The circuit through conductor means 294 then becomes closed 
causing energization of the field relay winding 196 and consequent closure 
of contacts 200 and 202. With contacts 200 and 202 thusly closed, the 
motor-pump means 24 is energized and the bilge liquid pumped from the 
intake 26 to and through the outlet 28 thereby lowering the level of the 
bilge liquid 22 (FIG. 1). 
When the level of the bilge liquid reduces itself to an elevation below 
that of upper probe 40, the apparent resistance of such probe 40, as far 
as detector means 340 is concerned, becomes relatively great thereby 
causing the input terminals 86 and 88 of gate 50 to experience relatively 
"high" input signals which, in turn, cause output terminal 94 to produce a 
"low" signal as an input to input terminal 96 of gate 52. However, since 
both input terminals 96 and 136 where previously experiencing "high" input 
signals and since the input signal on terminal 136 still remains "high", 
the signal on the output terminal 100 of gate 52 will remain "low" thereby 
enabling gates 58 and 54 to remain latched and continuing energization of 
pumping means 24 to further reduce the level of the bilge liquid. This 
latched condition will continue until, generally, the level of the bilge 
liquid is reduced to below that of the lower probe 38. 
When the level of the bilge liquid is thusly sufficiently reduced and probe 
38 is out of the liquid, the apparent resistance of the probe 38, as far 
as detector means 342 is concerned, appears to be relatively high thereby 
causing the signals applied to both input terminals 120 and 122 of gate 56 
to become "high" and the output at terminal 124 to become "low" which, in 
turn, is applied to input terminal 136 of gate 52 thereby now causing the 
output signal at terminal 100 of gate 52 to become "high". Generally, at 
the same time, the "low" output signal at terminal 124 is also applied via 
conductor means 126 to input terminal 130 of gate 58 causing: the output 
at terminal 140 to go "high"; the input at terminal 142 of gate 54 to go 
"high"; the output at terminal 144 of gate 54 to go "low" and the input at 
terminal 146 of gate 58 to go "low". Consequently, gates 54 and 58 become 
unlatched from each other and since the output of gate 54 is "low" the 
forward biasing of the Darlington circuit 152 is eliminated and the 
circuit through the emitter-collector diode of transistor 184 is in effect 
opened thereby causing de-energization of the field winding 196 and the 
pumping means 24. 
Now, after the pumping means 24 has been de-energized as already discussed, 
let it be assumed that for some reason, as for examples hull leakage, 
etc., the level of the bilge liquid again starts to increase. As it 
increases and first causes the lower probe 38 to be in contact therewith, 
the resulting apparent short circuit (apparent to detector means 342) of 
probe 38 results in a "low" signal to be experienced by input terminals 
120 and 122 of gate 56 thereby causing output signal on terminal 124 to 
become "high" which, in turn, causes a "high" input signal to be placed on 
terminal 136 of gate 52 and terminal 130 of gate 58. However, since 
immediately preceding, both input terminals 96 and 136 of gate 52 and both 
input terminals 146 and 130 of gate 58 had "low" input signals thereon, 
the outputs at terminals 100 and 140 of gates 52 and 58, respectively, 
will continue to have a "high" output. Therefore, both inputs to terminals 
102 and 142 of gate 54 remains "high" and the output signal at terminal 
144 of gate 54 also remains "low" thereby not placing the Darlington 
circuit 152 into conduction. 
When the level of the bilge liquid increases sufficiently to contact upper 
probe 40, the resulting apparent short circuit (apparent to detector means 
340) of probe 40 results in a "low" signal to be experienced by input 
terminals 86 and 88 of gate 50 thereby causing output signal on terminal 
94 to become "high" which, in turn, causes a "high" signal to be placed on 
input terminal 96 of gate 52. Consequently, since both input terminals 96 
and 136 are now at a "high" input signal, the output signal at terminal 
100 of gate 52 becomes "low" which, in turn, is applied to input terminal 
102 of gate 54. With this, gates 54 and 58 undergo latching by having: the 
output terminal 144 of gate 54 go "high"; the input terminal 146 of gate 
58 go "high"; the output terminal 140 of gate 58 go "low" and the input 
terminal 142 of gate 54 go "low". As a result, and as previously 
explained. Darlington 152 is made conductive and pumping means 24 
energized. 
Generally, in an arrangement as described, it can be seen that the lower 
probe means 38 serves, as the liquid level is rising, as a condition 
sensor placing the overall circuitry in a state of readiness to be 
triggered by the upper probe means 40 when such is brought into contact 
with the liquid. Further, as the level of the liquid gradually lowers, the 
probe means 38 in effect serves to assure that a sufficient quantity of 
such liquid is pumped as to assure the liquid level attaining at least a 
predetermined lower level. 
In view of the preceding, it should be apparent that the logic disclosed by 
the teachings of the invention could be employed, for example, in having 
three or more probe means for sensing the existance of various attained 
levels of liquid and, in turn, causing, for example, related sequential 
energization of a series of pumping means. This could especially be useful 
in, for example, large ships where first pumping means may not be able to 
handle hull seepage above a particular flow rate (as may be experienced 
during storms with little or no cargo) and wherein second pumping means 
may be able to provide the additional pumping capacity for such conditions 
but not for other seepage conditions as may be experienced during violent 
storms with full cargo. In the last exemplory condition, third pumping 
means would be energized. This would mean that smaller capacity pumps, at 
lower costs, could be employed and energized as needed and in response to 
continued rising of liquid level past a series of probe means. 
As illustrated, the invention may preferably be provided with time delay 
means comprised of resistor 92 and capacitor 250 and comprised of resistor 
128 and capacitor 254. That is, first considering resistor 128 and 
capacitor 254, as the water or liquid initially contacted probe 38, 
capacitor 254 became charged and such charge remained there through the 
entire described cycle of pumping means energization to shut-down. When 
the liquid level finally drops below the lower probe 38, capacitor 254 
starts to discharge through the resistor 128 and diode 132 and in so 
doing, continues the application of the "high" signal to input terminal 
130 of gate 58 thereby continuing the latched condition of gates 58 and 54 
and maintaining the pumping means 24 energized. Capacitor means 254 and 
resistor means 128 define an R-C circuit which, in one successful tested 
embodiment, delayed the de-energization of pump means 24 for approximately 
ten seconds after the level of the liquid decreased below the level of 
probe 38. This effectively prevents the premature de-energization of the 
pumping means 24 as may otherwise occur due to sloshing or the like of the 
liquid causing a very brief interruption of contact as between the lower 
probe 38 and the sloshing liquid. 
Similarly, considering resistor 92 and capacitor 250, when the level of the 
liquid rises sufficiently to contact upper probe 40, the initial current 
flow from output terminal 94 is ineffective to cause a "high" signal to 
occur at input terminal 96 of gate 52 until after capacitor 250 first 
becomes charged. Therefore, the R-C circuit comprised of resistor 92 and 
capacitor 250 is effective for causing a time delay between the time that 
the liquid first contacts the upper probe 40 and the time that input 
terminal 96 experiences a "high" input signal to ultimately energize 
pumping means 24. Consequently, such a "turn-on" time delay serves to 
prevent premature energization of the pumping means 24 due to, for 
example, sloshing or the like of the liquid causing a very brief contact 
as between the liquid and the upper probe 40. In one successful tested 
embodiment of the invention, the time delay provided by R-C network 92, 
250 was in the order of ten seconds. However, as should be apparent, if 
time delay means are employed for delaying the turning on and/or off of 
pumping means 24, the magnitude of such time delay may be selected to be 
any desired value. Further, it is contemplated that when such time delay 
means are employed for delaying both the energization and de-energization 
of the pumping means, the magnitudes of such respective time delays need 
not be even substantially equivalent to each other and, in fact, may be at 
substantial variance with respect to each other. It is also contemplated 
that resistance means 92 and/or resistance means 128 may be variably 
adjustable resistance means as to enable, if desired, selective adjustment 
thereof when installed within, for example, a water craft as to 
accommodate for possibly unique conditions of that water craft and/or 
surface conditions of the water in which that water craft is situated. 
In the preferred embodiment of the invention, related signal means 226 are 
provided in order to produce an output signal to indicate that the pumping 
means 24 has been energized for a preselected length of time. That is, in 
any particular situation given the volume of bilge liquid to be pumped-out 
and the pumping rate of the associated pumping means 24, it becomes 
possible to then determine the length of time that the pumping means must 
be energized in order to pump that given volume of bilge liquid to be 
pumped. If in that situation the pumping means continues to be energized 
especially for an extended time beyond that in which the pumping means 
should have been de-energized, such could be, for example: (a) the result 
of more bilge liquid having been originally present then normally expected 
and, therefore, the condition of the water craft hull should be checked in 
order to determine if unknown damage has been inflicted thereupon; (b) the 
result of internal damage in the pumping means and, therefore, the pumping 
means should be inspected; and/or (c) the result of the pumping system 
becoming clogged by dirt or the like. 
In any event, it is preferred that the operator be notified that a 
predetermined length of energized pump time has elapsed so that related 
inspection and/or maintenance relative thereto can be performed. 
To this end, referring to FIG. 2, the preferred embodiment of the invention 
provides suitable signal means 226 and associated circuit means. For 
example, when the output at terminal 140 of gate 58 goes "low", as 
previously described, capacitor 310 starts to charge and when it becomes 
sufficiently charged, both input terminals 164 and 166 receive a "low" 
input signal thereby causing the output at terminal 170 of gate 60 to go 
"high" resulting in transistors 208 and 216 being made conductive and 
enabling source 272 to energize the signal means 226. The charging time of 
capacitor 310, determined as by the R-C network of resistor 156 and 
capacitor 310, serves to establish the desired length of time after which 
the signal means 226 is activated. Preferably, zener diodes 232 and 375, 
as zener diode 206, are provided for transient protection. 
FIG. 3 illustrates a modification of the invention. Only those elements 
believed necessary to illustrate the modified form are illustrated and, 
further, such, if similar to those of preceding are identified with like 
reference numerals provided with a suffix "a". Otherwise, for purposes of 
discussion, the remainder of the modification of FIG. 3 may be considered 
as identical to the related remaining portion as shown in FIG. 2. 
In the embodiment of FIG. 3, collector 192a of transistor 184a is 
electrically connected as via conductor means 360 to one end of a voltage 
divider, comprised of resistance means 362 and 364, which, at its other 
end, is connected as by conductor means 366 to terminal 280a. A PNP power 
transistor 368 has its base 370 connected to the voltage divider as at 372 
and its emitter 374 connected to conductor means 366. The collector 376 of 
transistor 368 is connected as by conductor means 378 to pumping means 
24a. 
In the arrangement of FIG. 3, when Darlington 152a is made conductive, in 
the manner previously described with reference to Darlington 152 of FIG. 
2, current flow through the voltage divider causes power transistor 368 to 
become conductive thereby completing the circuit to and energizing pumping 
means 24a. In such an embodiment, the conductor means 294 of FIG. 2 is not 
needed. Further, in the preferred arrangement, suitable signal means, such 
as, for example, visual signal means as in the form of bulb means 380 is 
electrically connected as to conductor means 378 and grounded as at 382. 
Such bulb means 380 is generally diagrammatically depicted as being 
located as at 42 of FIG. 1. Accordingly, whenever pumping means 380-42 
indicates to the craft operator that the pumping means 24a is in an 
energized condition. Similarly, visual signal means in the form of bulb 
means may be provided as at 384, of the embodiment of FIG. 2, and 
connected to conductor means 332 while being grounded as at 386. 
It is further contemplated, referring to FIG. 2, that the signal means 226 
may in fact be auditory signal means as disclosed in, for example, U.S. 
Pat. No. 3,810,149 dated May 7, 1974, which is hereby incorporated by 
reference. If such auditory signal means as shown in, for example, FIGS. 
1, 2 and 3 of said U.S. Pat. No. 3,810,149 were to be employed, electrical 
terminal means 66 and 94 thereof could be respectively electrically 
connected to conductor means 228 and 224 of FIG. 2 of the invention. 
It should, of course, be apparent that the pumping means 24 may comprise a 
generally unitized electric motor and pump assembly or it may comprise 
separate electric motor means operativelyf connected to separate related 
pump assembly means. The specific form thereof forms no part of the 
invention and any suitable overall pumping means may be employed. 
It is also contemplated that pumping means may be driven as by, for 
example, engine means employed for propelling the water craft. For 
example, FIG. 4 illustrates an arrangement wherein the water craft 
propelling motor means is shown at 400 with related power take-off and 
transmission means 402 having one portion 404 of clutch means 406 
operatively secured thereto and driven thereby. Related bilge pump means 
408, having an inlet conduit 410 and outlet conduit 412, has shaft means 
414 which carries, as by a splined connection or the like, the second 
cooperating clutch portion 416 of clutch means 406. Suitable thrust 
bearing means 418, operatively connected to clutch member 416, is, in 
turn, operatively engageable by suitable lever-like means 420 so that as 
the lever 420 is rotated generally counterclockwise about pivot 422, lever 
420, through bearing means 418, moves clutch member 416 into operative 
engagement with clutch member 404 thereby enabling motor 400 to drive pump 
408 through take-off transmission 402 and shaft 414. A solenoid assembly 
424, having a movable armature 426 operatively connected to lever 420, 
when actuated causes the lever 420 to thusly move counterclockwise about 
pivot 422. As depicted, solenoid assembly 424 may be grounded as at 428 
while its other terminal is electrically connected as to conductor means 
332 of FIG. 2 and, of course, in such an arrangement, the pumping means 24 
are generally depicted in FIG. 2 would not be employed. Accordingly, in 
the modification contemplated in FIG. 4, when contacts 200 and 202 are 
closed (as previously described with reference to FIG. 2) solenoid 
assembly 424 becomes energized causing operative engagement of clutch 
members 404 and 416 and consequent activation of pump means 408. 
FIGS. 5, 6, 7 and 8 illustrate one specific embodiment of the invention. 
Referring in greater detail first to FIGS. 5 and 6, the assembly 440 is 
illustrated as comprising a housing 442 and a cover 444 with a printed 
circuit board assembly 446 situated generally within the housing and 
operatively connected to the cover 444 as through probes 40 and 38. As can 
be seen, the cover 444 is received within a complementary opening 448 and 
abuts against a peripheral-like flange or shoulder 450 of the cover and 
preferably sealed thereagainst as by sonic welding or the like. The lower 
end wall of housing 442 is provided with laterally extending flange-like 
portions 452 and 454 each provided with a slot 456 as to accommodate 
related fastening means 458 in order to secure the assembly 440 as to a 
lower disposed mounting surface 460 of the related water craft. Further, 
as best seen in FIG. 6, additional laterally displaced stabilizing 
abutment means 462 and 464 are preferably integrally formed with housing 
442 as to abut against the coacting mounting surface 460. 
Referring to FIG. 7, the printed circuit board assembly 446 is illustrated 
as preferably comprising a plurality of printed circuit portions 470, 472, 
474, 476, 478, 480, 482, 484, 486, 488, 490, 492, 494, 496, 498, 500, 502, 
504, 506, 508, 510, 512, 514, 516, 518, 520, 522, 524, and 526. Printed 
circuit portion 470 is shown provided with apertures 528, 530, 532, 534, 
536 and 538; portion 472 is shown provided with apertures 540 and 542; 
portion 474 is shown provided with apertures 544, 546, 548, 550, 552, 554, 
556, 558, 560, 562, 564, 566, 568 and 570; portion 476 is shown provided 
with apertures 572, 574, 576, 578, 580, 582, 584, and 586; portion 478 is 
shown provided with apertures 588, 590 and 592; portion 480 is shown 
provided with apertures 594, 596 and 598; portion 482 is shown provided 
with apertures 600, 602 and 604; portion 484 is provided with aperture 
606; portion 486 is shown provided with apertures 608, 610 and 612; 
portion 488 is provided with aperture 614; portion 496 is provided with 
aperture 616; portion 490 is shown provided with apertures 618, 620, 622, 
624, 626 and 628; portion 492 is shown provided with apertures 630, 632, 
634 and 636; portion 494 is shown provided with apertures 638, 640 and 
642; portion 502 is shown provided with apertures 644, 646, 648 and 650; 
portion 498 is shown provided with apertures 652, 654, 656, 658 and 660; 
portion 500 is shown provided with apertures 662 and 664; portion 504 is 
shown provided with apertures 666 and 668; portion 506 is shown provided 
with apertures 670, 672 674 and 676; portion 508 is shown provided with 
apertures 678, 680, 682 and 684; portion 510 is shown provided with 
apertures 686, 688, 690 and 692; portion 512 is shown provided with 
apertures 694, 696, 698 and 700; portion 514 is shown provided with 
apertures 702, 704, 706 and 708; portion 516 is shown provided with 
apertures 710, 712, 714, 716 and 718; portion 518 is shown provided with 
apertures 720, 722, 724 and 726; portion 520 is shown provided with 
apertures 728 and 730; portion 522 is provided with apertures 732, 734 and 
736; portion 524 is shown provided with apertures 738, 740, 742, 744 and 
746; and circuit portion 526 is shown provided with apertures 748, 750, 
752 and 754. 
Referring to both FIGS. 7 and 8, it can be seen that quad-chip 46, 48, 50, 
56 has its electrical leads 830, 832, 834, 836, 838, 840 and 840 
respectively received in apertures 702, 704, 720, 670, 724, 726, and 562 
while its leads 844, 846, 848, 850, 852, 854 and 856 are respectively 
received in apertures 626, 710, 712, 684, 736, 738 and 740. Diode 114 has 
its opposite leads respectively received in apertures 742 and 748; 
resistor 246 has its leads received by apertures 744 and 750; capacitor 
252 has its leads received by aperture 746 and 566; capacitor 328 has its 
leads received by apertures 628 and 570; capacitor 248 has its leads 
received by apertures 718 and 568; capacitor 324 has its leads received by 
apertures 696 and 708; resistor 78 has its leads received by apertures 752 
and 698; resistor 326 has its leads received by apertures 706 and 728; 
resistor 112 has its opposite leads received by apertures 692 and 694; 
diode 80 has its opposite leads received in apertures 690 and 716; 
resistor 240 has its leads received in apertures 688 and 714; resistor 92 
has its leads received in apertures 672 and 734; diode 98 has its leads in 
apertures 670 and 732; capacitor 250 has its leads in apertures 674 and 
560; capacitor 310 has its leads in apertures 624 and 652; capacitor 254 
has its leads in apertures 556 and 650; quad-chips 52, 54, 58 60 has its 
leads 802, 804, 806, 808, 810, 812, 814, 816, 818, 820, 822, 824, 826 and 
828 respectively received in apertures 640, 644, 634, 642, 668, 636, 558, 
622, 660, 658, 664, 666, 676 and 678; diode 132 has its opposite leads 
received in aperture 682 and 648; resistor 128 has its leads received in 
apertures 680 and 646; resistor 156 has its leads received in apertures 
632 and 656; diode 168 has its leads in apertures 630 and 654; diode 232 
has its leads in apertures 612 and 554; resistor 174 has its leads in 
apertures 616 and 662; transistor 208 has its terminals 210, 212 and 230 
received through a common opening 860 and respectively placed in contact 
with printed circuit portions 496, 488 and 486; resistor 288 has its 
opposite leads received in apertures 602 and 620; diode 286 has its leads 
received in apertures 600 and 530; resistor 362 has its leads in apertures 
532 and 592; resistor 364 has its leads received in apertures 588 and 540; 
transistor 368 has its terminals 370, 374 and 376 respectively received in 
apertures 590, 528 and 594; diode 206a has its leads received in apertures 
544 and 542; transistor 152a has its terminals 180a, 186a and 192a 
collectively received through a slot-like opening 862 and respectively 
placed in contact with printed circuit portions 484, 474 and 472; resistor 
151a has its leads received in apertures 606 and 638; zener diode 290 has 
its leads received in apertures 548 and 618; and transistor 216 has its 
terminals 214, 218 and 222 respectively received by apertures 614, 552 and 
608. Further, cable means 864 and 866 are provided with cable 864 being 
comprised of conductor means 334a and 378 while cable 866 comprises 
conductor means 190a, 224 and 284a. Conductor 190a is received in 
aperture 546, conductor 334a is received in aperture 550, conductor 224 is 
received in aperture 610, conductor 378 is received in aperture 598 and 
conductor 284a is received in aperture 534. Also, jumper or bridging type 
conductors 868 and 870 are provided with the opposite ends of conductor 
868 being received in apertures 754 and 586 while conductor 870 has its 
opposite ends received in apertures 686 and 728. Obviously, all of such 
leads and conductors situated generally within the recited apertures and 
openings are suitable electrically connected to the associated printed 
circuit portions as by, for example, soldering. 
As generally indicated, the conductors of cables 864 and 868 are preferably 
individually provided with outer electrically insulating material 872 and 
are, in turn, contained with respective common outer liquid sealing 
sheathing or covering 874. 
Preferably, and as depicted, transistors 216 and 368 are each operatively 
connected to respective generally U-shaped heat sinks 876. As generally 
typically illustrated in FIGS. 9 and 10, the transistor, such as 368, is 
preferably secured to and in intimate contact with the bight portion 878 
of the heat sink 876 as through coacting washer 880 and screw 882 
threadably engaged with bight portion 878. As best seen in FIG. 10, the 
arms 884 and 886 of the heat sinks 876 are preferably formed with slots 
888 as to thereby increase the effective heat dissipating surface area and 
to enhance air flow. 
As also generally depicted in phantom line in FIG. 8, if instead of the 
solid state version of FIG. 3, the relay version of FIG. 2 were to be 
employed, the relay 198 would be situated generally as depicted in phantom 
line, in FIG. 8, replacing the transistor 368 and associated heat sink 
876. 
Referring to FIGS. 5, 6 and 11 in conjunction with FIG. 8, it can be seen 
that wall 890 of housing 442 is provided with apertures 892 and 894 for 
enabling the passage therethrough of cables 864 and 866. Further a 
plurality of tubular-like extensions 896, 898 and 900 are also integrally 
formed in wall 890 and arranged as to be extending generally outwardly 
therefrom and situated as to have their axis generally passing through a 
line of centers determined by the axis of apertures 892 and 894. 
Preferably such extensions are situated on either side of apertures 892 
and 894. A sealing member 902, tightly receiving extensions 896, 898 and 
900 as well as cables 864 and 866 is then preferably tightly pressed 
thereabout and against wall 890 as by a plurality of screws 904, 906 and 
908 respectively threadably engaged with extensions 896, 898 and 900. 
As indicated in both FIGS. 5 and 6, printed circuit assembly 446 comprises 
electrically conductive probes 40, 38 and 910 with probes 40 and 38 being, 
respectively, the upper and lower level sensing probes schematically shown 
in FIGS. 1 and 2 while probe 910 is an electrically grounding probe or 
conductor means. In the embodiment disclosed, upper probe 40 has its one 
or inner end received through aperture 582 as to be in electrical contact 
with printed circuit portion 476 while probe 38 has its inner end received 
through aperture 730 as to be in electrical contact with printed circuit 
portion 520. The ground probe 910, similarly, has its inner end received 
through aperture 564 as to be in electrical contact with circuit portion 
474. 
All of such probes may be substantially identical and, as shown typically 
by probe 38, may be comprised of stainless steel having a major 
cylindrical body 912 with integrally formed annular flanges 914, 916 with 
an inner end 918 mechanically deformable as to lock such end onto the 
printed circuit board. The other end 920 extends beyond cover 444 as to be 
exposed to the bilge liquid. Preferably a boss-like portion 922 is 
provided by cover 444 which serves to coact with flanges 914 and 916, as 
by molding thereagainst and therebetween, to rigidly secure the cover to 
the related probe. It should be pointed out that the plurality of aperture 
572, 574, 576, 578, 580, 582 and 584 are provided in order to enable the 
selective location of the upper probe 40 at any such aperture, in any 
particular embodiment, in order to thereby attain the desired distance 
between the upper and lower probes 40 and 38 and thusly establish the 
bilge liquid level therebetween; that is, the elevation to which such 
liquid has to rise in order to activate the pumping means as previously 
described. 
Further, additional generally cylindrical supports 930 and 932 are provided 
at the other end as to be operatively secured to both the cover 444 and 
the printed circuit board and thereby hold that end of the printed circuit 
board assembly in spaced relationship to the cover 444. 
The embodiment as disclosed in FIGS. 5, 6, 7, 8, 9, 10 and 11 is made to be 
sealed as to prevent any leakage of the bilge liquid into the interior 
thereof thereby permitting such to be mounted in the water craft at any 
desired location without any short circuits occurring due to such leakage. 
As should be apparent, the probes 38 and 40, in the embodiments disclosed, 
employ alternating current; that is the preferred mode of operation. 
However, it should also be apparent that the invention can be practiced by 
having such probes 38 and 40 employ direct current. 
As has been previously stated, it isapparent that the invention, although 
described with reference to a bilge pumping system, is in fact capable of 
being practiced in various different environments and may, for example, be 
employed in situations for detecting a preselected level (or even a series 
of levels) of a particular liquid and to, in response thereto, creating or 
causing selected outputs to occur even to the extent that such outputs 
need not necessarily involve a pumping means. 
Although only a preferred embodiment and selected modifications of the 
invention have been disclosed and described, it is apparent that other 
embodiments and modifications of the invention are possible within the 
scope of the appended claims.