US 3863211 A
A plurality of pressure-activated electric switches are connected to pressures which are variable with an engine's speed of rotation or to comparatively constant fuel pressure, respectively; and an engine speed-of-rotation activated electric switch is connected to said engine which has an associated electrical power supply for use with said switches. Said power supply is connected through one of the constant-fuel-pressure-activated switches and a voltage regulator to electrical input terminals of the remainder of said switches in parallel circuits. These switches are activated in various combinations in accordance with the fuel-pressure/rpm/oil-pressure conditions which exist. A first logic circuit activates an alarm when the switch combination indicates a malfunction in the engine oil pressure. A second logic circuit is connected in parallel with said first logic circuit and is adapted to conduct only when impossible fuel-pressure/rpm/oil-pressure conditions are indicated which indicates malfunctions of said switches. An alarm is energized when said second logic circuit conducts.
Description (OCR text may contain errors)
willie States Patent 1 Latham, Jr.
 ABSTRACT l l DEVICE FOR WARNING OF MALFUNCTIONS OF ENGINE PRESSURE A plurality of pressure-activated electric switches are SYSTEMS AND OF "SELF connected to pressures which are variable with an en-  inventor; Maxwell Lamar, Jr" p BOX gines speed of rotation or to comparatively constant 468, Venice 70091 fuel pressure, respectively; and an engine speed-ofrotation activated electric switch is connected to said  Flled: May 1973 engine which has an associated electrical power sup-  Appi. 3 2 5 5 ply for use with said switches. Said power supply is connected through one of the constant-fuel-pressureactivated switches and a voltage regulator to electrical  U.S. Cl. 340/60, 340/62 input terminais f the remainder of Said Switches in  'f B60! 1/00 B60q 29/04 parallel circuits. These switches are activated in varil Fleld of Search, 340/60 52 240 ous combinations in accordance with the fuel-pressure/rpm/oil-pressure conditions which exist. A first  Refemnces cued logic circuit activates an alarm when the switch com- UNITED STATES PATENTS bination indicates a malfunction in the engine oil pres- 2,5s2.4s3 1/1952 Hallerberg 340/60 sure- A Second logic Circuit is Connected in Parallel 3.431555 3/1969 Leone 340/60 with said first logic circuit and is adapted to conduct 3,648,23 3/ Be 340/52 F only when impossible fuel-pressure/rpmloil-press'ure 3,723,964 3/1973 Lace 340/60 conditions are indicated indicates malfunctions of said switches. An alarm is energized when said sec- Primary ExaminerGlen R. Swann, Ill and logic circuit conducm Attorney, Agent, or Firm-James B. Lake, .lr.
2 Claims, 1 Drawing Figure CON. PRESS. I2 ACT. SW. +5VDC g CON. PRESS. v VOLT. REG. T ACT.SW.- ELEC. 24 J POWER CONDUT AND SUPPLY CONDUIT VAR PRESS. ACT. s w 28 lo CONDUIT 46 48 RPM 9 AND OR ACT. SW ENGINE L i CONDUIT AND WARNING 38 INDICATORS 3O 3! 44 VAR. 66 PRESS. ACT. SW. 50 2Q [60 OR AND 6, AND J- OR OR '52 AND \62 AND DEVICE FOR WARNING OF MALFUNCTIONS OF ENGINE PRESSURE SYSTEMS AND OF ITSELF FIELD OF THE INVENTION The invention relates to warning devices for engines, and more particularly to devices warning of malfunctions in engines lubricating pressure systems, and of its own possible malfunctions.
It is well known that oil pressures in operating engines vary with enginespeed or r.p.m. while fuel pressure remains comparatively constant. In a diesel engine, oil pressure varies with the speed from about 9 lbs. at idling to over 45 lbs at high speeds. The invention was primarily made for use with diesel engines and is so described hereinafter, but it could be easily applied to any variable pressure system.
DESCRIPTION OF THE PRIOR ART It is old in the art to provide warning devices to warn of a drop in oil pressure below that required at idling speeds. However an engine can be damaged seriously by a drop in oil pressure insufficient at high speeds to set off a low speed alarm.
It is an object of the invention to provide a warning device that will warn of insufficient oil pressure at low and high speeds and wherever desired therebetween of an associated engine.
It is also an object of the invention to provide a warning device that will warn of its own possible malfunctions.
Other objects and a fuller understanding of the invention may be had by referring to the following specifica tions, claims and drawings, in which:
BRIEF DESCRIPTION OF THE DRAWING The FIGURE is a block diagram of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the FIGURE, the invention 9 comprises in combination with an engine 10 and an electrical power supply 12, pressure and speed sensing switches 14 connected to said power supply and engine and responsive thereto for said switches to be opened and closed in combinations in accordance with parameters of pressures and speeds sensed. Switches 14 are electrically connected to a first logic circuit 16, which is responsive to malfunctions of said engines pressure systems as electrically disclosed by said combinations to energize a first warning indicator 48. A second logic circuit is connected to said switches 14 in parallel with said first logic circuit 16. This second logic circuit is responsive to malfunctions of switches 14 and probable malfunctioning of both switches and engine pressure systems to energize a second warning indicator 66.
In more particularity, the switches 14 comprise constant pressure activated switches 24 and 26, variable pressure activated switches 28 and 30, and switch 32, all arranged as shown in the FIGURE. Switch 24 electrically connects power supply 12 to a voltage regulator 34 which produces a controlled voltage compatible with logic circuits l6 and 20. Switches 26, 28, 30 and 32 are connected in parallel circuitry to voltage regulator 34. A conduit 36 connects switches 24 and 26 to a comparatively constant pressure fuel system of the engine 10 and closes them to ,on" position when engine 10 is running. A second conduit 38 connects switches 28 and 30 to a variable pressure oil system of engine 10; switch 28 being closed to on position under 15 lbs pressure and open to of position over l5 lbs, and switch 30 being closed to on position by pressures under 45 lbs. Any convenient means for sensing revolutions per minute of engine 10 is connected to switch 32 which is closed to on position by over 1400 rpm and to open to off position by less than 1400 rpm.
First logic circuit 16 comprises three and" gates 40, 42, and 44, and an or" gate 46. Gate 40 is electrically connected to the outputs of switches 26 and 28, gate 42 is electrically connected to output of switches 28 and 32, gate 44 is electrically connected to switches 30 and '32, and gate 46 is connected to the outputs of gates 40,
42, and 44, all as shown in the FIGURE. A first warning indicator 48 is connected to the output of gate 46.
Second logic circuit 20 comprises three or gates 50, 52 and 54 and four and gates 56, 58, 60 and 62. Gates 50 and 56 are respectively connected in parallel circuitry to the outputs of switches 26 and 28 with an inverter 64 inverting the output of switch 28 to gate 50. Gates 52 and 58 are respectively connected in parallel circuitry to the outputs of switches 30 and 32 with inverters 64 inverting the output of switch 30 to both gates 52 and 58, and an inverter 64 inverting the output of switch 32 to gate 58 only. Gate 60 is connected to the outputs of gates 50 and 58, and gate 62 is connected to the outputs of gates 56 and 52. Gate 54 receives the output of gates 60 and 62. A second warning indicator 66 is connected to the output of gate 54.
The device operates as follows. With engine 10 not running there is no constant pressure to activate switch 24 to close, thus there is no voltage applied to the logic circuits of invention 9. When the engine is started, constant pressure activated switches 24 and 26 are activated by engine fuel line pressure through conduit 36 to close to on positions. Power supply 12 supplies Combs.
ac/dc voltage to voltage regulator 34 which generates a voltage that is applied to switches 26, 28, 30 and 32, and is also applied (not shown) to bias gates of logic circuits l6 and 20. The state of each switch either off or on determines whether no voltage or a voltage is supplied the logic circuits by them individually. Switch 26 is adapted to always be closed with the engine running. Therefore only the three remaining switches 28, 30 and 32 are positionable to either of or on positions in various combinations of positions. In all there are nine possible switch outputs to the gates of the logic circuits. These and resulting voltage to warning indicators 48 and 66 can be tabulated as follows in a truth table.
switches lst. W. 2nd. W.
24 26 28 32 3O Ind. Ind. l l 0 0 0 O 0 l 2 l l 0 0 0 0 l 3 l l 0 0 l O O 4 l l 0 l 0 0 0 5 l l 0 l l l 0 6 l l l O 0 l l 7 l l l 0 l l 0 8 l l l l 0 l l 9 l l l l l l I In the above table, the off or open position of switches is indicated by 0, and the on" or closed position by l to represent a no voltage or a voltage output, respectively, of each of said switches.
In combination 1, switch 26 is malfunctioning and the second warning indicator is energized. Both switches 24 and 26 are activated by engine running.
In combination 2, with switch 28 opened by over lbs. pressure and switch32 opened by less than 1400 rpms, switch 30 is malfunctioning by not being closed by less than 45 lbs. pressure for the indicated rpms. Second warning indictor is energized.
In combination 3, normal operation is indicated in the under 1400 rpm speed range and no warning indicators are energized.
In combination 4, normal operation is indicated in the over 1400 rpm range and no warning indicators are energized.
In combination 5, switch 32 indicates rpm over 1400 and switch 30 indicates oil pressure below 45 lbs to energize first warning indicator.
In combination 6, there are two possibilities, either switch 30 is malfunctioning in showing over 45 lbs pressure at low speed of under 1400 rpms to energize the second warning indicator, or the engine is malfunctionig and running with too high oil pressure to energize the first warning indicator. Since engine malfunctions can be readily checked with pressure gauges, determination of which warning is correct is easily ascertainable.
In combination 7, switches 28 and 30 properly indicate low oil pressure below 1400 rpm speed range, and first warning indicator is energized.
In combination 8, either switch 30 or 32 is malfunctioning with switch 32 showing more than 1400 rpms and the oil pressure should be lower than 15 lbs if switches 30 and 32 are normal. Both warning indicators are energized.
And in last combination 9, either obvious switch malfunction or caused by rapid oil pressure drop while running above 1400 rpm to energize both warning indicators.
The number of ranges (rpm/pressure) can be increased as desired by adding switches and gates to the logic circuits.
What is claimed is:
1. In combination with an engine having a variablepressure oil system and an electrical power supply, a warning device comprising:
a. Engine-running sensing means connected to the engine and electrical power supply and responsive thereto for sensing if said engine is running and to provide an electrical output in accordance therewith;
b. Variable-pressure sensing means connected to said engine and electrical power supply and responsive thereto for sensing variations of pressure in said variable-pressure oil system and to provide and electrical output in accordance therewith;
c. Speed sensing means connected to said engine and electrical power supply and responsive thereto for sensing rpm of said'engine and to provide an electrical output in accordance therewith;
(1. First logic circuit means connected to the respective electrical outputs of said engine running sensing means, pressure and speed sensing means for comparison and responsive thereto produce an electrical output indicative of engine malfunctione. Second logic circuit means connected to the respective electrical outputs of said engine running sensing means, pressure and speed sensing means, and in parallel circuit with said first logic circuit means, for comparison and responsive thereto provide an electrical output indicative of said sensing means malfunctioning;
f. And warning indicator means connected to respective electrical outputs of said first and second logic circuit means for energization thereby to warn of malfunctioning.
2. A warning device as described in claim 1 wherein said engine-running sensing means comprises:
constant pressure activated switches connected to the fuel line of said engine and adopted to be switched to on position by the pressure in said fuel lines, and to of position by no pressure.