US3489912A - Safety control - Google Patents

Description

Jan. 13, 1970 H. HOFFMAN, JR

SAFETY CONTROL 3 Sheets-Sheet 1 Filed Dec. 7. 1967 F l G. 2. 3 4

oERou VENYILATE SAFE DAN E T A L T N E V INVENTOR HOWARD HOFFMAN JR.

ATTORNEY Jan. 13, 1970 Filed Dec. '7, 1967 3 Sheets-Sheet 2.

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12 VOLT 24 BATTERY INVENTOR H. HOFFMAN, JR

SAFETY CONTROL HOWA-RD HOFFMAN JR.

BY M "7 ATTORNEY Jan. 13, v H, HOFF JR D SAFETY CONTROL Filed D60. '1, 1967 I 3,Sheets-heet 3 FIG.6.

l 62 DOUBLE ENGINE INSTALLATION 64 I00 P-m/"q G EGEEE TDA 42 EMERJGN. CONTROL 66 BILGE OR ENGINE i OFF r COMPARTMENT ONT T i BLOWER I N I I I FOUR POLE I ga 68 DOUBLE THROW: 7 LEVER LOCK i i/ i wi m T'" F i -1 W 1 i i I i i l L ma ma Tc" 8 E a 0 IGNITION CIRCUIT -r"": 5 i I i I k f L I w fil 7 d FOUR POLE DOUBLE 'rnnow RELAY L... J ea 54 -f- IBOSECOND I AMBER uems TIME DELAY RELAY 1 ass/W VENTILATE 82 GREEN\\'/L|6HTS I I 38 Q J 32 ,34 U n SAFE 78 I I 1 L I 1 q To sznsms RED fibusms =,---i- ELM.

M IE] 302) i I Mm COMBUSTIBLE VAPOR DETEcTdR F; :13 WW [2 VOLT 24 BATTERY i INVENTOR HOWARD HOFFMAN JR.

A'E'TORNEY United States Patent 3,489,912 SAFETY CONTROL Howard Hoffman, Jr., 350 Minute Arms Road, Union, NJ. 07083 Filed Dec. 7, 1967, Ser. No. 688,887 Int. Cl. 1363 2/06 US. Cl. 307-9 12 Claims ABSTRACT OF THE DISCLOSURE Apparatus for preventing the starting of machinery, for example, electrically started machines, such as internal combustion engines situated in a potentially explosive atmosphere until the area surrounding the machinery has been subjected to a predetermined period of ventilation, the apparatus including a time delay relay connected in parallel with the ventilating means and switch means for interrupting the power supply or ignition circuit of the machinery which operates in response to the time delay relay, the apparatus further comprising a combustible vapor detector which prevents arming of the time delay relay and thus prevents completion of the power supply or ignition circuit after the predetermined ventilation period if a safe atmosphere does not yet exist.

BACKGROUND OF THE INVENTION Field of the invention The present invention relates to a safety control for machinery. More particularly, the present invention is directed to the prevention of operation of machinery situated in a potentially explosive environment at all times when that environment includes a dangerous concentration of combustible vapors and, in any event, until such time as a preliminary period of ventilation has been performed. Accordingly, the general objects of the present invention are to provide new and improved methods and apparatus of such character.

Description of the prior art While not limited thereto in its utility, the present invention is particularly well suited for use on boats. A typical pleasure craft will be powered by an internal combustion engine which will generally be located in a closed compartment in order to isolate passengers from dirt, noise and noxious fumes. As is well known, a substantial problem is presented by the potential accumulation of combustible vapors in the engine compartment. Severe damage and personal injury as a result of the explosion of such accumulated combustible vapors upon engine start-up is not an uncommon occurrence.

Combustible vapor detectors for shipboard and other uses have been available for some time. Such detectors, when they are functioning properly, merely provide an indication as to whether or not a potentially explosive atmosphere exists in the remotely located engine compartment. In the case of a component failure in the detector or, as is more likely, the lack of attention on the part of the operator, an attempt may :be made to start the engine regardless of the fact that combustible vapors have accumulated in the engine compartment to a dangerous concentration.

Previous attempts have been made to combine safety devices such as combustible vapor detectors with engine accessories so as to prevent engine operation when an unsafe condition exists. Such prior art devices have, however, not been particularly successful. One of the principal reasons for such lack of success resides in the fact that available combustible vapor detector devices will provide only a single output which typically will be commensurate with a dangerous or near dangerous con- 3,489,912 Patented Jan. 13, 1970 dition. Accordingly, prior art safety controls have not prevented starting of engines located in a compartment wherein combustible vapors have accumulated to a degree where, while an explosion may not be imminent, the accumulation of a relatively small additional amount of combustible vapors might precipitate an explosion.

SUMMARY OF THE INVENTION The present invention overcomes the above-discussed and other disadvantages of the prior art by providing a safety control that, when properly installed in a vessel powered with an internal combustion engine, will tend to minimize or eliminate the ever present hazard of an explosion or fire due to the accumulation of highly explosive gasoline or other combustible vapors in the bilge or engine compartment of such vessel. In accomplishing the foregoing and other objects, the present invention employs switch means for interrupting the ignition circuit of the engine until a sequence of events has occurred and a safe atmospheric condition exists in the engine compartment. The switch means for completing the engine ignition circuit operates in response to both a time delay relay and a second switch means which is controlled by a combustible vapor detector, the detector having its sensing element disposed within the engine compartment. The time delay relay is connected in parallel with the explosion proof motor of an engine compartment blower. Accordingly, when it is desired to start the engine or engines, it is first necessary to energize the time delay relay and thus the blower. The blower will thereupon ventilate the engine compartment for a period determined by the control element of the time delay relay, after which time, if the combustible vapor detector senses a safe condition within the compartment, the ignition circuit for the engine or engines will be completed and the engines may be started. The present invention also comprises visual and audible warning devices which operate synchronously with the various elements of the control system and means for overriding the control system and completing the ignition circuit in the case of a control system component failure.

BRIEF DESCRIPTION OF THE DRAWING The present invention may be better understood and its various advantages will become apparent to those skilled in the art by reference to the accompanying draw ing wherein like reference numerals refer to like elements in the various figures in which:

FIGURE 1 is a schematic view of the present invention installed on a vessel employing a single internal combustion engine;

FIGURE 2 is a front view of the control panel of a preferred embodiment of the present invention as it might be installed in the cabin of the vessel shown in FIGURE 1;

FIGURE 3 is a side view of the cabin installed control unit of FIGURE 2;

FIGURE 4 is a front view of a remote indicator panel as might be installed on the bridge of the vessel of FIGURE 1;

FIGURE 5 is a schematic of a preferred embodiment of the present invention; and

FIGURE 6 schematically depicts the preferred embodiment of FIGURE 5 as it may be modified for use on a twin screw vessel.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIGURE 1, a single screw vessel is indicated generally at 10. Vessel 10 is powered by a single internal combustion engine 12 which is located in the bilge or engine compartment, indicated generally at 14 of vessel 10. The batteries 16 which provide current for the starting of motor 12 are also usually located in compartment 14. In accordance with the present invention, also located in engine compartment 14 are an exhaust fan 18, which is driven by an explosion proof motor, and a sensing element 20 of a combustible vapor detector.

Sensing element 20 is connected to the safety control of the present invention, which is mounted in the cabin of vessel 10 and indicated generally at 22, by means of a two conductor cable 24. The driving motor for exhaust fan 18 is also connected to control 22 by means of a two conductor cable, not shown. Also connected to control 22, by means of cable 26, are the positive and negative terminals of battery 16.

As may be seen from FIGURE 2, safety control unit 22 provides the captain of the vessel with visual and audible indications of the operative mode of the control and of the condition of the atmosphere in the engine compartment 14. An amber ventilate light 28 will be illuminated during such times that exhaust fan 18 is operated. At all times when sensor element 20 is exposed to a dangerously high concentration of gasoline vapors, a red warning light 30 will be illuminated and a warning horn or siren 32 will be energized. During normal operating conditions when exhaust fan 18 is deenergized and the atmosphere in engine compartment 14, as sampled by sensor 20, does not contain a potentially explosive concentration of gasoline vapors, a green or safe condition light 34 will be illuminated. The safety control unit 22 of the present invention also presents to the vessel captain, via meter 36 of a combustible vapor detector which is indicated generally at 38, an indication of the degree of concentration of explosive vapors in compartment 14. Also mounted on the front panel of control 22 is the control lever 40 of a master control switch 42 (FIGURE Lever 40 of switch 42 has an off position, a control on position and an emergency ignition position. As will be explained in the discussion of FIGURE 5, control lever 40 of switch 42 must be placed in either the control or emergency position to complete the ignition circuit for engine 12.

FIGURE 3 is a side view of the control unit shown in FIGURE 2 with the wiring which interconnects the various components of the control eliminated in the interest of clarity. In both FIGURES 2 and 3, lever 40 of switch 42 is shown in the emergency ignition position. In FIG- URE 3, the additional components which comprise the safety control are mounted in a plug-in type unit indicated generally at 44.

Since vessel will often be operated from the bridge rather than from within the cabin, it is desirable to provide a remote indicator unit for control 22 at the bridge. In FIGURE 1, the remote indicator unit is indicated at 48. Indicator unit 48 is connected to the safety control 22 of the present invention by means of a four conductor cable 50. As may be seen from FIGURE 4, remote indicator unit 48 comprises a red danger lamp 52, an amber ventilate lamp 54 and a green safe condition lamp 56. Lamps 52, 54 and 56 of remote indicator unit 48 are, as may be seen from FIGURE 5, respectively connected in parallel with lamps 30, 28 and 34 of the main safety control unit 22.

Turning now to FIGURE 5, safety control 22 is shown schematically. In addition to combustible vapor detector 38, switch 42 and the warning lamps, the main elements of safety control 22 are a time delay relay 58 and a three pole, double throw relay, indicated generally at 60. Relays 58 and 60 will typically be mounted within plug-in unit 44 (FIGURE 3). Switch 42, as indicated above, has a neutral or off position and control on and emergency ignition positions. Switch 42 comprises a four pole, double throw, lever lock switch. The use of a lever lock type switch is dictated by the fact that, as will be explained below, the ignition circuit for the engine cannot be completed unless switch 42 is closed to either the control on or emergency ignition positions. Accidental opening of switch 42 as could occur if a lever lock switch were not employed, during operation of the engines would cause engine shut-down and thus would be highly undesirable. To operate on emergency ignition the safety control switch must be pulled out from its lever lock position and placed in the emergency ignition position.

The preferred embodiment of FIGURE 5 may best be understood from a description of the operation of the control system. When it is desired to start engine 12, under normal operating conditions, lever 40 of switch 42 will be moved to the control on position thereby closing the circuits between intermediate contacts, a, b, c, d and corresponding contacts a, b, c d (shown at the right in FIGURE 5). The closing of contacts a-a of switch 42 permits current to flow via cable 26 from the positive terminal of battery 16 through fuse 62 and, via initially closed contacts e-f of relay 60, to a first terminal of the motor of exhaust fan 18. The other terminal of the motor of exhaust fan 18 is connected via a conductor 64 and one conductor of cable 26 to the negative terminal of battery 16. Accordingly, the initial closing of switch 42 to the control on position energizes the exhaust fan 18 in engine compartment 14. At this time, the ignition circuit for engine 12 is interrupted by virtue of contacts h of relay 60 being initially in the open condition. Accordingly, engine 12 may not be started and ventilation of engine compartment 14 will occur.

Amber ventilate lights 28 and 54, respectively mounted on the panel of control unit 22 and remote indicator unit 48, are connected in parallel with the motor of exhaust fan 18 via conductor 66. Accordingly, closing of switch 42 to the control on position will provide the vessel captain with a visual indication that the engine compartment is being ventilated.

Also connected in parallel with the motor of exhaust fan 18, via conductor 68, is the control element 70 of time delay relay 58. Thus, current will begin to flow through control element 70 simultaneously with the energization of the exhaust fan. After a predetermined time, three minutes in a preferred embodiment, the temperature of control element 70 will have increased sutficiently so as to cause closing of a pair of bimetallic contacts n-o of relay 58.

The closing of switch 42 to the control on position also connects, via fuse 72 and contacts 0-0 of switch 42, combustible vapor detector unit 38 to the positive terminal of battery -16. Combustible vapor detector 38, which is permanently connected to the negative terminal of the battery, may be a Heathkit model 25 vapor detector unit which includes warning horn 32, meter 36 and the remotely located sensor 20. Vapor detector 38 also includes a solenoid operated relay, indicated generally at 74, having contacts p, q and r. As shown in FIGURE 5, the solenoid of relay 74 is deenergized thereby indicating the presence of a potentially dangerous concentration of explosive vapors in engine compartment 14. It is to be understood, however, that the absence of dangerous accumulation of gasoline vapors could also be indicated by the energized condition of relay 74.

As shown in FIGURE 5, when vapor detector 38 senses a dangerous condition it generates a signal commensurate therewith; in the embodiment of FIGURE 5 such signal being indicated by the closing of contacts p-q of relay 74. Horn 32 will then be energized via conductors 76 and 78 to provide an audible warning to the vessel captain. Simultaneously, warning lights 30 and 52 will be energized via conductors 76, 80 and 82 and contacts d-d of switch 42 to provide a visual warning that a dangerous condition exists. As long as the dangerous condition in engine compartment 14 persists, contacts p-r of relay 74 will not close and thus time delay relay 58 will not be armed since contact n of relay 58 will not be connected to the positive terminal of battery 16. The time delay relay 58 is, under normal conditions, armed via conductor 84,

contacts p-r of vapor detector relay 74 and conductor 86 which connects the vapor detector to the positive terminal of battery via contacts c-c' of switch 42. It should be noted that contact of time delay relay 58 is connected to the positive side of solenoid 88 of relay 60, the other side of solenoid 88 being permanently connected to the negative terminal of battery 16. Accordingly, since relay 58 cannot be armed until such time as a safe condition is sensed in the engine compartment, relay 60 will not operate even though the contacts of relay 58 are closed indicating a three minute ventilation of engine compartment 14 by exhaust fan 18. Accordingly, the exhaust fan 18 will continue to operate as long as the unsafe condition persists in engine compartment 14.

Considering now the condition where the atmosphere within engine compartment 14 contains a low concentration of gasoline vapors and vapor detector 38 thus generates a signal which energizes the solenoid of relay 74, contacts p-r of relay 74 will be closed thus arming contact n of time delay relay 58. Simultaneously, the positive terminal of battery 16 will be connected to contact k of relay 60 via conductor 90. When the three minute ventilation period has occurred, contacts no of time delay relay 58 will close thereby permitting current to flow through solenoid 88 of relay 60 thus operating the relay. The closing of contacts hof relay 60 will complete the ignition circuit for engine -12 thereby permitting the starting of engine 12 in the usual manner. The closing of contacts k-m of relay 60 will establish, via conductor 92, a path for current flow through solenoid 88 of relay 60 and thus relay 60 becomes self-latched. The opening of contacts e-f of relay 60 will deenergize the motor of exhaust fan 18 and ventilate lights 28 and 54 which are connected in parallel therewith. The closing of contacts p-r of vapor detector relay 74 will, of course, deenergize warning horn 32 and lamps 30 and 52. The closing of contacts k-m of relay 60 will also via conductors 92 and 94, energize safe condition lamps 34 and 56 thus providing the vessel captain with a visual indication that the ignition circuit for engine 12 has been completed and he may now attempt to start the engine.

Considering now the condition when the engines have been started and are operating. If a dangerous concentration of combustible vapors accumulates in engine compartment 14, a signal will be provided by combustible vapor detector 38 which will cause deenergization of the solenoid of vapor detector relay 74 thereby opening its contacts pr and closing contacts p-q. As explained above, the closing of contacts pg of vapor detector relay 74 will energize warning horn 32 and danger lights 30 and 52. Simultaneously, since terminal k of relay 60 will no longer be connected to the positive terminal of battery 16, current will no longer flow through solenoid 88 and relay 60 will be unlatched and its contacts will return'to the position shown in FIGURE 5. Accordingly, the ignition circuit established by the closing of contacts hof relay 60 will be interrupted and engine 12 will be shut down. Simultaneously, in the manner above-described, the motor of exhaust fan 18 will be energized as will ventilate lamps 28 and 54. Forced ventilation of engine compartment 14 will thus be initiated. At the same time, current will resume flowing through control element 70 of time delay relay 58. Thus, every three minutes, the contacts n-o of time delay relay 50 will be closed and the state of vapor detector relay 74 will be sampled to determine whether a safe condition exists in the engine compartment. Exhaust fan 18 will continue to run until such time as the sensing of a safe condition causes energization of vapor detector relay 74 and the arming of time delay relay -8.

In order to enable operation of the vessels engine in the event that there is a component failure in the control systern, the preferred embodiment of FIGURE 5 is provided with an override or emergency ignition operational mode. Should the boat engine shut down, and after a thorough visual inspection it be determined that the shut down was caused by a component failure in the safety control itself, the lever 40 of master control switch 42 may be moved to the emergency ignition position (shown in broken lines on FIGURE 5). In the emergency ignition position, contacts 11-11 of switch 42 will be closed thus completing the ignition circuit for the engine. Also, the red or danger lamps 30 and 52 will be illuminated, current being supplied to the lamps via fuse 72, contacts 0! and d of switch 42. In addition, the exhaust fan 18 and amber ventilate lights 28 and 54 will be energized through the closing of contacts aa" of switch 42. Accordingly, in the emergency ignition operational mode, the ventilate and danger lights will be on, the exhaust fan will operate and the ignition circuit will be completed for the purpose of allowing the vessel to be returned to its home base or the nearest safe anchorage until the necessary repairs to the safety control can be made. Illumination of the danger lights 30 and 52 is to remind the operator that the safety control is inoperative and that extra caution and safe operating procedures must be observed.

The embodiment of the present invention shown schematically in FIGURE 6 is designed for employment on a twin engine vessel. The circuitry shown in FIGURE 6 is similar to that of FIGURE 1 with the exception that three pole, double throw relay 60 of FIGURE 5 has been replaced by a four pole, double throw relay 100. The extra pair of contacts on relay provide means for interrupting and completing the ignition circuit for a second engine. The exercise of control over a second engine also requires that the connections to master switch 42 be rewired as shown to provide for the completion of the ignition circuit for the second engine via contacts c-c" in the emergency position, and to contacts s and u in the relay 100; and current is supplied through fuse 72 and contacts d, d and d" to the lines 86 and 82. This rewiring of the circuit results in danger lights 30 and 52 being energized only when the control system is in the emergency mode of operation. Thus, under emergency conditions, the vapor detector is not operative and the vessel operator must himself take care of possible dangerous conditions. The red warning lights 30 and 52 will keep the operator aware of the potential emergency condition. Under the normal control mode of operation, the audible alarm 32 will be energized whenever a dangerous condition in the engine compartment is sensed by combustible vapor detector 38.

While preferred embodiments have been shown and described, various modifications and substitutions may be made thereto without departing from the spirit and scope of the present invention. Accordingly, it is to be understood that the present invention has been described by way of illustration and not limitation.

What is claimed is:

1. Apparatus for the remote control of the operation of machinery situated in a compartment wherein an explosive atmosphere may accumulate, the apparatus comprismg:

means for ventilating the compartment wherein the machinery is situated;

means for sensing the condition of the atmosphere in the compartment and for generating a signal commensurate with the combustibility thereof;

time delay switch means;

means for simultaneously energizing said ventilating means and said time delay switch means;

means responsive to a signal generated by said sensing means and indicative of a non-combustible atmosphere in the compartment for applying power to a first terminal of said time delay switch means whereby said time delay switch means will be armed only when a safe atmosphere exists in the compartment; and

second switch means connected to a second terminal of said time delay switch means and to said means for applying power to a first terminal thereof, said second switch means being responsive to the operation of said time delay relay and the generation of a signal indicative of a non-combustible atmosphere for completing a power supply circuit to the machinery whereby the machinery may be operated only after an enforced ventilating period determined by said time delay relay arming of which is controlled by said means responsive to a signal generated by said sensing means providing for operation of said machinery only when said atmosphere in the compartment is non-combustible.

2. The apparatus of claim 1 wherein said second switch means comprises:

a self latching relay having its solenoid connected to the second terminal of said time delay relay, a first pair of contacts of said relay being connected to a supply circuit for the machinery, said first pair of contacts being closed as a result of current flow through said solenoid as a result of the operation of said time delay relay and said means for applying power thereto.

3. The apparatus of claim 2 wherein said time delay relay has its control element connected in parallel with said ventilating means.

4. The apparatus of claim 3 wherein said self-latching relay further comprises:

a second pair of contacts connected in series with said parallel connected ventilating means and time delay relay, said second pair of contacts being opened in response to energization of said solenoid of said self-latching relay, whereby said ventilating means will be deenergized when the starting circuit for the machinery is completed.

5. The apparatus of claim 4 wherein said self-latching relay further comprises:

a third pair of contacts connected in parallel with said contacts of said time delay relay whereby a path for current through said solenoid will be maintained after deenergization of said time delay relay.

6. The apparatus of claim 1 wherein said second switch means comprises:

a self-latching relay having its solenoid connected to the second terminal of said time delay relay, a first pair of contacts of said relay being connected to a supply circuit for the machinery, said first pair of contacts being closed as a result of current flow through said solenoid as a result of the operation of said time delay relay and said means for applying power thereto and with the addition of first indicator means connected in series with said means for applying power to said time delay relay first terminal.

7. The apparatus of claim 6 further comprising:

second indicator means connected in parallel with said ventilating means.

8. The apparatus of claim 7 further comprising:

third indicator means connected in parallel with said second switch means.

9. The apparatus of claim 1 wherein said second switch means comprises:

a self latching relay having its solenoid connected to the second terminal of said time delay relay, a first pair of contacts of said relay being connected to a supply circuit for the machinery, said first pair of contacts being closed as a result of current flow through said solenoid as a result of the operation of said time delay relay and said means for applying power thereto, said self-latching relay further comprises a second pair of contacts connected in series with said parallel connected ventilating means and time delay relay, said second pair of contacts being opened in response to energization of said solenoid of said self latching relay, whereby said ventilating means will be deenergized when the starting circuit for the machinery is completed.

10. The apparatus of claim 9 further comprising:

first indicator means connected in series with said means for applying power to said time delay relay first terminal.

11. The apparatus of claim 10 further comprising:

second indicator means connected in parallel with said ventilating means.

12. The apparatus of claim 11 further comprising:

third indicator means connected in parallel with said second switch means.

References Cited UNITED STATES PATENTS 2,526,446 10/1950 Zurit et al. -.5 X 2,569,252 9/1951 Omeron.

3,292,568 12/1966 Morrell 115-.5 3,315,584 4/1967 Van Ranst.

ROBERT K. SCHAEFER, Primary Examiner T. B. JOIKE, Assistant Examiner Us. (:1. X.R.

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