Fuel-Air Ratio Control by Sensing Exhaust Temperature

Technical Field

This invention relates generally to inter- nal combustion engines and more particularly to compensating devices for automatic control of fuel- air mixtures in response to exhaust gas temperature.

Background Art

Due to possible malfunctions or to engine lug down caused by engine overloading, proper fuel- air ratios sometimes are not maintained. For example, when engine lug down occurs, associated turbocom- pressor slow down .starves needed air supply to a fuel- air ratio controller. As a result, an associated rack or fuel adjusting member is automatically adjusted to decrease the fuel rate. If the fuel rate were not de¬ creased, engine damaging overheating would occur as well as possible damage to the turbocompressor.

One problem with the above-described auto- matic adjusting is that the response time is slow and in fact is slow enough to permit some damage.

In the past, sensors have been used to sense overheating of engine coolant systems and to actuate automatic fuel-air ratio adjustment. This is bene- ficial but reaction time is slow due to the time re¬ quired for the coolant to overheat and the subsequent sensing.

In view of the above, it would be advanta¬ geous to provide automatic adjusting of fuel-air ratio having relatively fast response time to engine over¬ heating which overcomes the problems associated with the prior art.

Disclosure of the Invention

In one aspect of the present invention, the problems pertaining to the known prior art, as set forth above, are advantageously avoided. 5 This is accomplished by providing fuel-air ratio control by sensing exhaust gas temperature in¬ cluding a temperature sensitive member connected between an exhaust manifold and an exhaust inlet of a compressor. A valve is connected to and is actuated

10 by the temperature sensitive member.

The foregoing and other advantages will become apparent from the following detailed description of the invention when considered in conjunction with the accom¬ panying drawings. It is to be expressly understood,

15 however, that the drawings are not intended as a definition of the invention but are for the purpose of illustration only.

Brief Description of the Drawings In the drawings: 20 FIGURE 1 is a diagrammatic view illustrating this invention; and

FIGURE 2 is a graphic view illustrating this invention.

Best Mode for Carrying out the Invention 25. The fuel-air ratio control apparatus of this invention is illustrated in Figures 1 and 2 and gener¬ ally designated 10. The apparatus includes an internal .combustion engine 12 having inlet 14 and exhaust mani¬ folds 16 connected to the engine 12 as is well known. 30 . A turbocompressor 18 is connected to the engine 12 via an exhaust conduit 20 interconnecting exhaust manifold 16 and exhaust inlet 22 of compressor 18. A stream of exhaust gas flows from manifold 16 via conduit 20

■ O. s, ^l

to inlet 22 for driving compressor 18. The gas then exhausts at exhaust pipe 24.

The compressor 18 being driven by the ex¬ haust gas draws clean air through air cleaner 26 and into the compressor 18, as is well known. The clean air exits the compressor 18 at outlet 28 and a stream of clean air flows from outlet 28 to inlet manifold 14 via conduit 30.

A conventional first means is provided for actuating a rack or fuel adjusting member 52 for con¬ trolling adjustment of the amount of fuel fed or in¬ jected into engine cylinders (not shown) . This first means comprises a fuel-air ratio controller 34 connected to a bleed line 36 which bleeds pressure off clean air stream conduit 30. The controller 34 is connected to rack 32 so that an engine lug down or malfunction resulting in slowdown of turbocompressor 18 will cause a decrease of air pressure in bleed line 36. This decrease will permit spring 38- to urge piston 40 to the left as viewed in Figure 2. As a result, clasp 42 will engage rack 32 and de- creasingly adjust the fuel feed to engine 12.

According to this invention, it is pre¬ ferred that a second means for adjusting rack 32, such as relief valve 44, is connected in fluid com¬ munication with bleed line 36 via conduit 37. Valve 44 includes a relief port 46 and a valve element 48 urged to close port 46 by resilient member or spring 50. A means for sensing exhaust temperature such as ther o expanding rod 52 is connected in conduit 20 between exhaust manifold 16 and exhaust inlet 22. Rod 52 is preferably a type K thermocouple per ANSI-ASTM-E230-77 and ANS-MC96.1 and is inserted

directly into the exhaust stream. One end 51 of the rod 52 is adjustably secured in conduit 20 whereas another end 53 is free to move relative to conduit 20. Rod 52 is adjustably secured to conduit 20 by a nut 54 threaded thereon. In any event, end 53 of the rod 52 is free to move due to expansion in response to being heated and due to contraction in response to being cooled.

Rod 52 is connected to valve element 48 at end 53. Thus, movement of rod 52 due to expansion will extend the length of rod 52 and urge element 48 to the right against spring 50, as viewed in Figure 2. As a result, port 46 is opened and pressure in valve 44 is relieved. This pressure relief has the desired effect of causing piston 40 to move as above-described and decreasingly adjust the fuel feed to engine 12 via movement of rack 32.

Industrial Applicability

With the parts assembled as set forth above, it can be seen that a decrease in pressure in bleed . line 36 permits movement of piston 40 resulting in adjustment of rack 32. Thus, the almost immediately detectable presence of increased temperature in con¬ duit 20 will expand rod 52 and move element 48 away from port 46 to relieve pressure in line 36 via valve 44.

The foregoing has described fuel-air ratio control by sensing exhaust gas temperature with a temperature sensitive member connected between an ^' exhaust manifold and an exhaust inlet of a compressor. A valve is connected to and actuated by the tempera¬ ture sensitive member.

Other aspects, objects and advantages of this invention can be obtained from a study of the drawings, the disclosure and the appended claims.