US3545421A - Engine control system - Google Patents

Description

I United States Patent [111 3,5 5,

3,153,403 10/1964 Dobbs l23/198(D2)X [72] Inventor Don S. Strader San Lake cityutah 3,199,523 8/1965 McEatheron l23/41.15 [21] Appl. No. 738,706 FORElGN PATENTS Continuation-impart of Ser. No. 729,653, 246,580 1/ 1963 Australia ..1.23/198(D2)UX May 16, 1968, abandoned. 693,873 7/1953 Great Britain l23/41.15 [22] June Primary Examiner-Wendell E. Burns [45] Patented l9 Attorney-Robert R. Finch [731 Assignee EnvlrotechCorporation Palo Alto, California acorporafion Elawaraby ABSTRACT: A control system for automatically reducing assignments speed of an overheated internal combustion engine. The system includes gas-operated normally closed fuel and air valves which are urged to the open position by control gas 54 ENGINE CONTROL SYSTEM maintained at operative pressure. A conduit for conducting 10 ,8 i m control gas to the valves is provided and has associated therewith control elements that are in heat exchange relation- [52] US. Cl. 123/198, ship with the engine-exhaust and which vary the rate of control 123/4L15 gas flow to the valves inversely to variations in the engine ex- [51] 1nt.Cl. Folp 11/14 I haust temperature Means are alsoprovided to reduce g Fozb 77/ 08 pressure as gas flow rate reduces thereby allowing the fuel and [50] Field of Search 123/ 198(D2), air valves to move toward the closed position h the engine 5 overheats. When the engine cools, full control gas flow is restored to completely reopen the fuel and air valves. The [56] References Cited system may be arranged to operate the valves sequentially so UNITED STATES PATENTS the air valve closes last and opens first thus reducing fire 1,869,429 8/ 1932 King et al 123/4115 danger. The system also provides basic cooling means com- 2,687,008 8/1954 Van Vactor.. 123/ 198(D2)X prising water injection into the exhaust gases from each 3,107,693 lO/1963 Puster et al 123/ 198(D2)X cylinder at a rate proportional to engine speed.

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DON S. STRADER ATTORNEY PATENTEI] nan 8l97fl 8.545421 sum 2 BF 4 INVENTOR.

DON STRADER QM ATTORNEY This is a continuation-in-part of my copending application US. Pat. SerfNo. 729,653, filed May 16, 1968 for Engine Control System, now abandoned.

BACKGROUND OF THE INVENTION This invention relates generally to apparatus for automatically decelerating or stopping an internal combustion engine whenever its temperature exceeds a predetermined maximum. It is of particular-application to engines used in closelyconfined operations, such as underground mining, where safety requirements dictate that the exhaust manifolds be maintained below a specified temperature.

Control of the exhaust temperatures is effected by injection of water into the exhaust gases in the manifold at avolume rate proportional to the engine speed. This is a successful system but there are cases where overwork or failure of the water injection system may cause or allow overheating. It is desirable, indeed, often required, that provision be made to slow down or stop as required to avoid dangerous overheating. This invention provides an automatic control system meeting such requirements. I

SUMMARY OF THE IN VENTION This invention provides an apparatus for automatically reducing the fuel and/or air supply to an overheated engine to slow down or stop the engine until it cools to a safe temperature.

In a specific modification of theinvention, basic control of the engine temperature is effected by water injection separately into the gases exhaustingfrom each cylinder rather than just into the exhaust manifold.

The invention includes on and off valves for the fuel and air lines. Each valve is constructed, usually be spring loading, to be normally off or closed. A control system-is associated with the valves and includes for each valve a gas operated valve actuator, means for supplying control gas at operative pressure.

.gas flow rates whereby gas pressure on the actuator reduces below the full open operative level whereby the valve moves toward the closed position when the engine temperature exceeds a predetermined maximum.

A bleed orifice or vent is located in the conduit ahead of the valves. Control gas is continuously supplied to the system at a rate to maintain operative pressure in the conduit and to satisfy thecapacity of the orifice. So long as the gas flow is adequate to maintain full operative pressure on the valves while satisfying demands of the bleed orifice the valves will remain open. If gas flow reduces below the rate required to satisfy the orifice, gas already in the system will flow to the orifice to make up the deficit, pressure on the valve actuator will reduce and the valves will move toward the closed position to restrict fuel and air.

As used in this specification, the term standard gas means control gas at the temperature and pressure at which it reports to the bleed orifice and/or valve actuators during normal engine operation.

For purposes of this invention the important measure is the rate of supply of standard gas from control elements in the engine to the valve actuators and/or the bleed orifice. If this rate is reduced, the engine will slow down.

In accordance with this invention, control gas flow is reduced inversely to engine temperature increases by heating the gas or by bleeding the gas from the system or physical throttling of its flow. In any case, the supply of standard gas is reduced below that needed to keep the fuel and air valves open.

In one form of the invention the control gas flows through a control element of high thermal conductivity maintained in heat exchange relationship with the engine exhaust whereby the gas temperature varies directly with engine temperature. In another modification the control element may include valving to throttle or restrict gas flow as temperature increases and vice versa, and a further modification includes a temperature responsive vent valve for each cylinder in heat exchange relationship to gases exhausting therefrom. Control gas passes successively through each of these valves en route to the actuators on the fuel and air valves. If the vent valve overheats, it

opens to vent gas from the system thereby closing the fuel and air valves.

A specific modification of the invention includes special valving whereby the air and fuel valves are operated sequentially sothat on overheating the fuel valve closes ahead of the air valve; and after the engine cools, the air valve opens ahead of the fuel valve.

BRIEF DESCRIPTION OF THE DRAWINGS So that the invention maybe more: readily understood and carried into effect, reference is made to the accompanying drawings which are offered by way of example only and are not be to be taken as limiting the invention:

FIG. 1 is a side elevational view of a mining machine embodying the invention.

FIG. 2 is :a top view of an internal combustion engine equipped with the control system of this invention.

FIG. 3 is an elevational view of a control element equipped with an internal water injection nozzle. The view shows in dotted lines the internal passage through which the control gas passes.

FIG. 4 is a sectional view taken in the plane of line 4-4 of FIG. 3 looking in the direction of the arrows.

FIG. 5 is a schematic representation of a control system embodying the invention.

FIG. 6 is a sectional view of gas operated valve adapted for use in this invention.

FIG. 7 is a schematic representationof a control system embodying a form of the invention employing vent'valves on each cylinder.

FIG. 8 is a sectional view of a heat responsive vent valve mounted in the gas discharge conduit from a cylinder.

BRIEF DESCRIPTION OF PREFERRED EMBODIMENT FIG. 1 illustrates a mining machine 11 equipped with a bucket 12 and traction wheels 13 and driven by a diesel or ignition-type internal combustion engine Mequipped with all usual controls.

As shownin FIG. 2, exhaust gases discharge through an intermediate housing 16 hereinafter referred to as a control element, into manifolds 17 thence to a final exhaust pipe 18.

Basic control of the exhaust gas temperature is effected by injection of water into the gases through a nozzle 19 (see FIG. 3) mounted in each control element 16. The water is supplied from a reservoir 21 via a pump 22 and suitable conduits 23.

To accommodate the higher exhaust temperatures resulting from increased engine speed, the water pump 22 is belt driven from a pulley 24 mounted directly on the crankshaft whereby the quantity of water injected into the exhaust gases varies directly with engine speed.

The water injection system is usually adequate to maintain engine exhaust temperature within safe limits during normal operation, but it makes no provision for cutting off the engine in case overheating occurs due to abnormal work loads or failure of the water injection system.

As described below, the control system of the present invention will throttle down the engine whenever overheating occurs for any reason.

As illustrated, the control system includes a control element 16 connected between each cylinder and the exhaust manifolds 17. A gas passage 26 is formed within the wall of the control element 16, and control gas, which is usually air, is supplied from-a pressured tank 27 via a pressure regulator 30 and conduit 25 to the first one of the control elements 16. After passing successively through all the control elements, the control gas flows on to the air and fuel valves. The internal passages 26 of the several control elements 16 are connected in series by short pieces of conduit 25. Since the control elements are connected in series overheating of any single engine cylinder will actuate the control system to throttle down the engine.

As shown in FIG. 5, after passing through the several serially connected control elements 16, the control gas stream from conduit 25 splits: One portion flows through a branch conduit 28 connected to the actuator section of the fuel valve 29. Another portion flows through a branch conduit 31 to the actuator section of the air valve 32, and a final portion escapes through ableed orifice 33 located in the main conduit 25. In connection with the bleed orifice, it should be noted that the fuel and air valves 29 and 32 are normally closed but during operation, they are urged open by the pressured control gas and the gas must be supplied at a rate sufficient to maintain operative pressure on the valves 29 and 32 and also to satisfy the demands of the bleed orifice 33.

For additional safety, the system is arranged to open the air valve ahead of the fuel valve on startup; and to close the fuel valve ahead of the air valve on throttling down. This is effected by a valving system that on startup provides a relatively free flow of gas to the air valve while restricting flow to the fuel valve and, on shutdown, provides a restricted flow of gas from the air valve and a relatively free flow from the fuel valve. This system includes restrictions 34 and 36 in conduits 28 and 31 respectively leading to the air and fuel valves. Each of these restrictions permits relatively more gas flow than does the main bleed orifice 33 at the same pressure so that, in operation, control gas will flow to the valves preferentially to the bleed orifice.

In connection with location of the air and fuel valves, the fuel valve may be located close to the point of injection to the carburetor, or injection nozzles if they be used, while the air valve should be located adjacent the intake manifold.

A bypass conduit 37 leads around the restriction 34 in the conduit 28 and a check valve 38, permitting gas flow only away from the fuel valve, is located in this bypass conduit.

Another bypass conduit 39 leads around. the restriction 36 on the control gas conduit 31 leading to the air valve. This bypass is equipped with a check valve 41 permitting gas flow only toward the air valve.

Thus, on startup, gas flows more freely to the actuator for the air supply valve than it does to the fuel valve actuator. This opens the air valve ahead of the fuel valve. If the engine overheats, the flow of control gas reduces below that needed to satisfy the entire demand of the bleed orifice 33. When this happens, gas flows away from both valves but it flows more freely away from the fuel valve than from the air valve so that fuel flow is reduced faster than is air flow.

Variation of control gas flows inversely to the engine exhaust temperature is accomplished by flowing the gas in indirect heat exchange relationship to the engine exhaust gases and, where desired, by physically throttling the gas flow.

As shown in FIGS. 3 and 4, both of these steps may be achieved in a control element 16 having thick walls of a material having a high coefficient of thermal expansion and of high thermal conductivity. Increased exhaust temperatures heat the gas. Increased gas temperature reduces the flow of standard gas from the orifice. At the same time, the cross-sectional area of the passage 26 is reduced thus restricting gas flow. When gas flow falls below the capacity of the bleed orifree 33 in terms of standard gas, gas will escape from the fuel and air. valve actuators to make up the deficit thereby reducing pressure and throttling down the engine.

Although the system as described is quite satisfactory it sometimes hunts as it hovers near the critical temperature. This may be minimized by a quick acting valve such as provided by a bimetallic diaphragm 43 mounted in a chamber 42 cut into the control element 16 in the path of the gas passage 26. The diaphragm forms one wall of the passage 26 and when it overheats, it snaps inwardly of the chamber to sharply reduce the flow area and the flow of control gas.

FIG. 6 illustrates a simple gas pressure actuated air valve 32 employed in the system of FIG. 5.

The valve 32 comprises a body 44 divided into a closed pressure or actuator chamber 46 and a flow chamber 47. Fluid, such as air or fuel, is admitted to the flow chamber via an inlet 48 whence it flows through an internal port 49 thence to outlet 51. The port 49 is normally closed by a plug 52 that is urged into the port by a diaphragm spring 53.

An impervious flexible diaphragm 54 is mounted in the actuator chamber 46 and a stiff rod 56 interconnects the plug 52 and the diaphragm. Control gas enters the actuator chamber 46 from the conduit 31, as hereinbefore explained. When gas pressure on the diaphragm is sufficient, the diaphragm spring 53 is overcome whereby the plug 52 moves out of the port 49 thus allowing air to flow from the air line 48 through the valve to the outlet 51. If the pressure in chamber 46 falls below operative pressure, as will occur on engine overheating, the spring-loaded plug 52 moves into the port 49 thus restricting flow.

The fuel valve 29 is identical in construction and operation to the air valve 32 and operates in response to gas supplied by conduit 28 to control fuel flow to the engine through the fuel line 58.

When the engine has been idle, it is possible that the control gas tank 27 will be empty. To enable startup under these conditions the valves 29 and 32 may be provided with an external control 59 for opening the valves manually until control gas pressure builds up to take over. Alternatively, the valves may be bypassed by manually valved conduits 61.

In operation, when control gas pressure is up and the engine is below the specified safe temperature, the fuel valve 29 and the air valve 32 are both urged to the full open position by gas acting on the diaphragm 54 in each valve body 44.

The control gas flows serially through the passages 26 in the control elements and is supplied at such a rate and pressure that the valve is held open while some gas escapes continuously through the bleed orifice 33. If the engine temperature rises, the control elements get hotter thus reducing control gas flow. As the gas flow reduces, gases escape from the valves through the bleed orifice 33. Thus pressure is lost, the valves move toward the closed position and the engine throttles down.

The check valve 38 on the bypass 37 of the gas line 28 to the fuel valve allows gas to flow freely away from the fuel valve. On the other hand, the check valve 41 in the bypass conduit 39 for the gas line 31 to the air valve blocks gas flow and forces it to escape only through the restriction 36 at a relative ly slow rate. This insures that the fuel flow will be restricted ahead of air flow valve so that no unconsumed raw fuel will be left in the engine.

When full flow of control gas resumes, the check valve 41 allows free gas flow to the air valve thus opening it immediately. On the other hand, check valve 38 blocks gas shunting it through the restriction 34 to the fuel valve. Thus, the fuel valve opens slowly relatively to the air valve. This avoids flooding of the engine.

Although the invention has been described in connection with an embodiment in which the control gas passing through the control elements works directly on the gas operated valves it is obvious that other arrangements may be made within the scope of this invention. For instance, two sources of control gas may be employed. A low-pressure source may pass through the control elements to actuate an on-ofi' pilot valve which may be similar to the valve shown in FIG. 6. This valve controls the flow of a high-pressure gas stream that in turn operates a separate on-off valve on the air and/or fuel lines. In this way a stronger valve may be used on the air and fuel line. In any such arrangement a bypass or escape port 45 will be provided in valve 32which will open when the valve is closed to enable gas loss from the air or fuel valve. to allow them to move to the closed position. t

In place of the above-described arrangement employing separate bypass conduits 37, 39, check valves 38, 41, and restrictions 34, 36, it is within the scope of the invention to utilize the soscalled fluidic diode 71 (see FIG. 7) which combines the functions of the aboveelements and permits free gas flow in one direction and reduced flow in the reverse direction (see FIG. 5). Obviously one such unit may be placed in the air line and another in the fuel line. Fluidic diodes of the type above mentioned can be obtained from Norgren Fluidics, a division of the CA. Norgren Company and are described in their publication identified as NFSS- l /1 0M/9-67/Rv FIGS. 7 and 8 illustrate a form of the invention in which.

vent valves are employed to regulate control gas flow. The system illustrated in FIG. '7 follows the same general layout as that shown in FIG. hence similar parts are designated by the same reference numerals and their description is not repeated except where necessary for clarity.

In this modification, the control elements comprise temperature responsive vent valves 62 mounted one in each of the exhaust pipes from a single cylinder and in heat exchange relationship withthe gases therefrom. Control gas flows to the valve via conduit 25, passing into inlet 63 through upper chamber 64 to exit from outlet 65. The valve is provided with a vent 66 that may communicate with the upper chamber 64 through a port 67; The port is normally closed by springloaded cover 68 to which is secured an adjustable pushrod 69. An expansion element 70 is secured in the lower part of the valve to be acted on by exhaust gases. When the expansion element is heated beyond a predetermined level, it acts on the ps pushrod to move the cover 68 thereby uncovering port67 to allow gas to escape from vent 66. This results in a loss of control gas flow with the result that the fuel and air valves close as hereinafter described.

When the vent valves 62 are inserted in the system shown in FIG. 7 they will function similarly to the throttling valve. That is, overheating will result in a reduction of gas flow toward the fuel and air valves. i I

The system illustrated in FIG 7 is generally similar to that of FIG. 5 but employs fluidic diodes 71 in place of the check valve circuits of the system shown in FIG. 5. The diodes permit unrestricted flow in one direction but restricted back flow exactly as do the check valve circuits. x

In the system shown in FIG. 7, more positive actuation of the fuel and air valves 72 is obtained by use of pilot valves 73. These pilot valves may be identical in construction and operation to hereinbefore described valves 32 but are used tocontrol the flow of high pressure air supplied from the tank 27 via regulating valve 74 and conduits 75. The high-pressure air acts on the spring-loaded pistons 76 to move the fuel and air valves to the open position and hold them there so long as operative control gas pressure is in the system. When the vent valve 62 opens and pressure is lost, the fuel and air valves close. The diodes 71 are arranged to effect sequential closing of the fuel and air valves as hereinbefore described in connection with the check valve system.

Iclaim:

1. In combination with an internal combustion engine, a control system comprising a first open-close valve on the engine fuel supply line, a second open-close valve on the engine air supply line, a source of pressure gas for actuating said valves, a heat sensitive control means responsive to engine operating temperature, and valve control means responsive to said heat sensitive control means for sequentially closing said first valve then said second valve when the temperature of the engine exceeds a predetermined range and for sequentially opening said valves in reverse order when the engine temperature falls below said predetermined range.

2. Apparatus according to claim 1 including actuators for normally holding said valves closed and adapted when acted pressure to open said valves, said source of control gas including means adapted to provide a continuous supply of control gas at said operative pressure, abranched conduit for conducting gas from said gas source to each of said actuators to maintain operative pressure thereon for holding said valves open, said heat sensitive control means includes a vent in said conduit between said gas source and said actuators for releasing gas from said conduit, means associated with said control means for normally closing said vent and for opening the same in response to temperatures above a predetermined level, and means for mounting said heat sensitive control means in heat exchange relationship to gases from said engine.

3. Apparatus according to claim 1 including actuators for normally holding said'valves closed and adapted when acted on by control gas maintained at a predetermined operative pressure to open said valves, said source of control gas including means adapted to provide a continuous supply of control gas at said operative pressure, a branched conduit for conducting gas from said gas source to each of said actuators to maintain operative pressure thereon for holding said valves open, and means guiding said conduit in heat exchange relationship with said engine at a location between said gas source and said actuators to vary the flow of control gas through said conduit toward said actuators inversely to variation in engine temperature.

4. Apparatus according to claim 1 including actuators for normally holding said valves closed and adapted when acted on by control gas maintained at a predetermined operative pressure to open said valves, said source of control gas including means adapted to provide a continuous supply of control gas at said operative pressure, a branched conduit for conducting gas from said gas source to said] actuators, a bleed orifice in said conduit of capacity such that at a given rate of gas flow operative gas pressure is maintained in said conduit between said orifice and actuators simultaneously with a continuous flow of gas outwardly from said orifice, and a heat sensitive gas flow controller in heat exchange relationship with said engine and operative in said conduit between said gas source and-said orifice, said gas flow controller being adapted to regulate the rate of flow of gas through said conduit inversely to changes in engine temperature and when the engine temperature exceeds a predetermined level to reduce said gas flow below said given rate required to maintain operative pressure in said conduit between said orifice andactuators.

5. Apparatus according to claim 4 in which said gas flow controller comprises a section in said main conduit in heat exchange relationship to the engine and a valve operative in said section of conduit to vary gas flow therethrough.

6. Apparatus according to claim 4 in which said gas flow controller comprises a heat responsive vent valve in said conduit adapted to be normally closed and to open for releasing gas from the conduit in response to "temperatures above a predetermined level.

7. Apparatus according to claim 5 in which said valve comprises a bimetallic diaphragm arranged to expand into the path of gas flow on temperature increase.

8.. Apparatus according to claim 4 wherein said valve control means comprises supplemental flow controllers on said conduit leading to said fuel valve between said bleed orifice and said valve, said supplemental controllers being adapted to restrict gas fiow toward said valve and provide relatively unrestricted gas flow away from said valve, and supplemental flow controllers on said conduit leading to said air valve adapted to provide relatively unrestricted gas flow toward said second valve and to restrict gas flow away from said second valve.

9. Apparatus according to claim 4 wherein the engine has a plurality of separate combustion'chambers, and said heat sensitive gas flow controller comprises a conduit mounted to pass in heat exchange relationship successively to all of said chambers.

10. Apparatus according to claim 9 with the addition of a on. by control gas maintained at a predetermined operative 75 plurality of nozzles, one nozzle being provided for each combustion chamber and being mounted to inject water into the exhaust gases from its respective combustion chamber, and

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