US3886922A

US3886922A - Engine speed governor with peak load control

Info

Publication number: US3886922A
Application number: US397964A
Authority: US
Inventors: Charles H Frick
Original assignee: Motors Liquidation Co
Current assignee: Motors Liquidation Co
Priority date: 1973-09-17
Filing date: 1973-09-17
Publication date: 1975-06-03
Anticipated expiration: 1992-06-03

Abstract

A mechanical governor for a compression-ignition engine is provided in a preferred embodiment with separate springs for idle and maximum speed control plus a load control spring which modifies the effective rate of the maximum speed spring near the maximum speed range so as to flatten the engine peak load curve. A wave spring washer placed between the high speed spring plunger flange and its seat may be used as the load control spring.

Description

United States Patent Frick June 3 1975 [54] ENGINE SPEED GOVERNOR WITH PEAK 3,566,849 3/1971 Prick 123/140 R LOAD CONTROL 3,707,144 12/1972 Galis et a1. 123/140 R [75] Inventori Charles H. Frick, Pontiac, Mich. FOREIGN PATENTS OR APPLICATIONS [73] Assigneez General Motors Corporation, 847,463 9/1960 United Kingdom 123/140 R Detroit, Mich. Primary Examiner-Charles .1. Myhre [22] Filed: Sept. 17, 1973 Assistant Examiner-Paul Devinsky NO: Attorney, Agent, or Firm-Robert Outland 57 ABSTRACT [52] US. Cl. 123/140 R; 123/140 11 C 1 [51 1 Int Cl Fozd 1/04 A mechanical governor for a compression-ignition en- [58] Fieid MC 140 J gine is provided in a preferred embodiment with separate springs for idle and maximum speed control p1us [56] References Cited a load control spring which modifies the effective rate of the maximum speed spring near the maximum UNITED STATES PATENTS speed range so as to flatten the engine peak load 2,669,983 2/1954 Reddy ct a1 123/140 R curve A wave spring washer placed between the high speed spring plunger fiange and its seat may be used 3:139:875 7/1964 Link 123 140 R as the load control Sprmg' 3,530,895 9/1970 Staudt ct a1 123/140 R 3 Claims, 5 Drawing Figures PATENTED JUN 3 i975 X42 .0 .rZmUmma mw oammmOI ENGINE R.P.M. PERCENT OF MAX. f, 5 J6? ENGINE SPEED GOVERNOR WITH PEAK LOAD CONTROL BACKGROUND OF THE INVENTION This invention relates to mechanical engine governors for internal combustion engines and, more particularly, to the provision of load control spring means for flattening the high speed portion of the engine horsepower curve in combination with a maximum-idle speed governor of a type used on diesel engines for automotive vehicles.

It is known in the art relating to governors for compression ignition engines to provide a mechanical governor having means for controlling the engine idle speed as well as preventing operation above a preset maximum speed range. One type of governor used for such purposes includes centrifugal flyweights which act through a linkage against an idle speed spring and, upon its full compression, on a high speed spring which controls maximum speed. Between idle and maximum speeds the fuel input is controlled manually by the operator of the engine or vehicle over a normal load, or horsepower output, curve which increases with engine speed up to the maximum speed setting. At this point the governor reduces fuel input to prevent overspeeding the engine.

The rising torque and horsepower curve characteristic of such engine-governor arrangements has led to the development of truck transmissions, for example, hav ing many gear ratio selections so that the operator can select for any given condition a ratio which will permit operation of the engine at or near its maximum horsepower range. In some cases, the numerous gear changes used to operate a truck at maximum power over varying highway speeds have involved excessive shifting which tends to actually reduce overall operating efficiency of the vehicle. To overcome this, engine and control developments have been made to provide a more constant horsepower output over a wider speed range than was previously available.

Such developments have included the use of a spring device called a power control spring on the injector rack actuating mechanism within the engine which tends to resist the last portion of the movement of the injector racks toward the full or maximum fuel position. With this device, when the engine is at full throttle or full rack, the power control spring opposes the force of the high speed spring in the governor so that maximum engine output is reduced and the upper end of the load curve is flattened. The effect of the arrangement is lessened or eliminated, however, when the engine is operated at other than full rack. In addition, the position of such power control springs within the engine enclosure makes them susceptible to tampering and readjustment by the vehicle operator, leaving the possibility that the engine may be readjusted to permit excessive horsepower output leading to excessive wear.

SUMMARY OF THE INVENTION The present invention provides a mechanical governor for a compression-ignition engine in which a load control spring for cutting off the peak of the engine horsepower curve, thus flattening the curve, is provided within the governor enclosure where it is less susceptible to tampering by the operator. In addition, the load control spring is provided in the form of a simple wave-type washer which is placed between the shoulder of the plunger that is acted upon by the governor high speed spring and the stop for the plunger, so that the load control spring opposes the high speed spring only during the initial portion of the plunger movement as it compresses the high speed spring. This places the peak load control spring in the governor speed control portion where it effectively flattens the load curve near the maximum speed setting of the governor under any degree of mechanical setting of the injector racks from full rack to the lowest rack setting at which maximum speed may be attained.

A result of the use of a power control spring according to the invention, as in some other power-controlled arrangements, is to permit the provision of higher output injectors in an engine without increasing its maximum horsepower output, while allowing the maximum horsepower to be attained over an extended speed range. This, in turn, allows practical use of a transmission in the vehicle having fewer gear ratio changes, thus simplifying operation of the vehicle.

Other features and advantages of the arrangement will be more fully understood from the following de scription ofa specific embodiment, taken together with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING In the drawing:

FIG. 1 is a cross-sectional view of a portion of the mechanism of a mechanical engine governor formed according to the invention;

FIG. 2 is a cross-sectional view of the governor of FIG. 1, taken generally in the plane indicated by the Line 2-2 of FIG. 1;

FIG. 3 is a fragmentary view of a portion of FIG. 2 enlarged to show certain details of the mechanism;

FIG. 4 is a pictorial view of a peak load control spring in the form of a wave washer as used in the illustrated embodiment of the invention; and

FIG. 5 is a graphical illustration of characteristic horsepower-speed curves showing the effect of the load control spring in flattening the engine power curve at various fuel rack settings.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENT Referring now to the drawings in detail, numeral 10 generally indicates a mechanical engine governor for a compression ignition engine including a housing 12 having a mounting surface 14 which is adapted to be secured to the end face of the blower housing or other suitable portion of a compression ignition engine.

Within the housing 12 is a rotatable shaft 16 having a splined end portion 18 that is adapted to be connected to the rotating blower shaft or other suitable portion of the engine for driving the shaft 16 at a speed proportional to engine speed. Shaft 16 carries a pair of pivotally mounted flyweights 20 which, upon increasing speed, are increasingly urged outwardly by centrifugal force around pivots 22. Fingers 24 extending from the flyweights engage a sleeve 26 which acts through a bearing 28 on an operating fork 30. The fork 30 is connected to an operating shaft 32, that is mounted for oscillation in bearings, only one of which 34 is shown. Operating shaft 32 is fixed to an operating shaft lever 36 having a pair of angularly disposed arms 38, 40.

At the end of arm 40 of the operating lever, a differential lever 42 is piv'otably mounted intermediate its ends on a pivot pin 43. One end of arm 42 is bifurcated at 44 to receive the end of a pin 46 extending from operating mechanism 48 adapted to be connected through an external lever 50 with the accelerator pedal, not shown, ofa vehicle or other means for manual control of the engine by the operator. At its other end, differential lever 42 is pinned to a link 52 which is, in turn, connected to an oscillating lever 54 having an end portion 56 connectible with engine fuel rack actuating means, not shown, for moving the engine injector racks between their maximum and minimum fuel positions.

The other arm 38 of operating shaft lever 36 carries an adjusting screw 58 which engages a cup-shaped cap 60 carried for reciprocation within a recess 62 of a cylindrical plunger 64. A low (idle) speed spring 66 extends between the cap 60 and a seat 68 connected to the plunger 64 by adjustable means for setting the spring preload. A flange stop 70 on the cap 60 is engagable with the end of the plunger 64 to limit compression of the spring 66 and provide a solid connection thereafter between the lever 36 and plunger 64.

An adjustable cup-like retainer 72, surrounding one end of plunger 64, receives and supports one end of a high speed spring 74. The other end of the spring 74 acts against a flange 76 on the plunger 64, biasing the plunger to the right as viewed in FIG. 2. Plunger 64 is reciprocably supported in the bore 78 of a support member 80 which forms a portion of the housing 12. An annular abutment 82 surrounds the bore 80 and is located in opposition to the flange 76 of the plunger, which is biased toward the abutment by the high speed spring 74.

An annular wave washer 84 is disposed between abutment 82 and the plunger flange 76, forming a peak load control spring in accordance with the invention. Wave washer 84 preferably takes a form as shown in FIG. 4 having generally the form of a flat annular steel blank with, in this instance, three wave portions 86a, b and c spaced equally around the annulus and being deformed in the same direction from the flat base to provide a compressible spring of predetermined rate. Alternatively, other suitable forms of spring washers or springs could be used as load control springs.

Upon operation of an associated engine, not shown, shaft 16 of the governor will be rotated at a speed proportional to engine speed, causing the flyweights to move outwardly and apply a force proportional to speed, tending to rotate the operating shaft lever 36 in a counter-clockwise direction as viewed in FIG. 2. Such movement of the speedresponsive means (which includes lever 36) moves the pivot pin 43 downwardly, causing the differential lever 42-to swing in a clockwise direction, as shown in FIG. 2, around the pin 46. This movement, in turn, moves the internal actuating means comprising link 52 and lever 54 in a direction tending to move the external fuel rack actuating mechanism of the engine toward the minimum fuel position.

The force generated by the flyweights is opposed initially by the bias of low speed spring 66, together with the high speed spring 74. At low engine speeds, high speed spring 74 overcomes spring washer 84, causing it to be flattened between the plunger flange 76 and abutment 82, thereby holding plunger 64 in its farthest rightward position, as viewed in FIG. 2. At idle speeds, low speed spring 66 extends cap 60 against adjusting screw 58 in the lever 36 and controls the engine idle speed by yielding or extending as necessary to permit the flyweight force to control fuel flow at the required amount for maintaining idle speed.

Actuation of the accelerator by the operator to increase speed moves the lever 50 so that pin 46 is moved generally downwardly, as shown in FIG. 2, pivoting lever 42 and the internal actuating means toward a position of increased injector rack, thus increasing the engine speed. This results in an increased force from the flyweights which completely compresses spring 66, causing the stop flange of the cap to engage the end of plunger 64, thus providing a non-yieldable connection between the lever 36 and the plunger.

Between idle and the maximum controlled engine speed, the rack position is set manually by the engine operator. However, when the maximum controlled speed range is reached, the force of the flyweights 20 becomes high enough to begin compressing the high speed spring 74 which yields, as necessary, to reduce the injector output by moving the racks toward the minimum fuel position so that the maximum controlled speed is not exceeded. The range of maximum controlled speeds is shown in FIG. 5 to extend from the maximum controlled speed at no load down to about percent of the maximum controlled speed at no load when the engine is operated under full load.

FIG. 5 compares the effect on engine horsepower and speed of two similar governors, one with and one without a peak load control spring 84. The solid line 88 represents the maximum load-speed curve of the governor without the load control spring. It shows a generally rising horsepower curve which peaks near 90 percent of the maximum speed, at which point further speed increase causes reduction of the engine fuel input until at the maximum speed position, fuel input is completely shut off.

The addition of the load control spring 84 to the combination causes the speed and load-speed curve to follow the dashed line in the portion of the speed range from about 70 to percent of the maximum speed, changing the increasing horsepower curve in this area to a relatively flatter curve in which the change in horsepower with speed is minimized. In FIG. 5, the upper set of

lines

88, 90 represent engine output at full rack, while the lower set of lines 92, 94 represent the corresponding output figures at a reduced manual rack setting.

The effect of the peak load control spring is to reduce the effective rate of the spring combination acting on the plunger 64 in the initial portion of the compression of the high speed spring as it moves away from the abutment 82 to control maximum speed. This effect causes movement of the plunger to begin at a lower speed than otherwise and to continue at a faster rate in proportion to increasing speed until the end of the travel of the wave washer 84 is reached. Further compression of the high speed spring thereafter follows the same diagonal line as would be the case if the wave washer were not present in the combination.

Although the embodiment described utilizes a wavetype washer for the peak load control spring, it would be possible within the scope of the invention to utilize other forms of short travel springs which might be applied in suitable manner to modify the effective spring rate of the high speed spring as it acts on the plunger in the initial portion of its travel. Since these and other modifications may be made within the scope of the invention as described, it is intended that the invention not be limited except by the language of the following claims.

I claim:

1. A maximum-minimum speed limiting governor in combination with a compression-ignition engine having a fuel rack actuator for varying fuel input to the cylinders, said governor comprising a housing,

first actuating means in said housing and connectible with such fuel rack actuator, said actuating means being movable between maximum and minimum fuel positions,

engine speed responsive means in said housing and connected with said first actuating means, said speed responsive means being movable between maximum and minimum speed positions and arranged such that movement thereof toward said maximum speed position moves said first actuating means toward its minimum fuel position and movement of said speed responsive means toward its minimum speed position moves said first actuating means toward its maximum fuel position,

support means in said housing and having a cylindrical bore with an annular abutment surrounding said bore at one end thereof,

a cylindrical plunger received for reciprocating movement in said bore, said plunger having an annular flange extending axially opposite said abutment,

a cap member reciprocably received within a recess in said plunger and low speed spring means in said recess and biasing said cap member outwardly therefrom and into engagement with and urging said speed responsive means toward its maximum speed position, said cap member having a flange stop thereon engagable with the end of said plunger to limit compression of said low speed spring and provide a non-yielding connection between said plunger and said speed responsive means at operating speeds above a preset engine idle speed,

a high speed spring received on said plunger and acting between said annular flange and said housing so as to bias said annular flange toward said support abutment, and

a peak load control spring acting between said abutment and said annular flange and opposing the bias of said high speed spring during the initial portion of the travel of said plunger flange away from said abutment,

said speed responsive means being operable to apply a force increasing with increasing engine speed against said low and high speed springs through said abutment and annular flange without permanent deformation of said washer.

3. A governor for limiting the maximum speed of a compression-ignition engine operable at varying speeds and loads and having a fuel rack actuator for varying fuel input, said governor comprising a housing enclosing first actuating means connectible with such fuel rack actuator, said means being movable between maximum and minimum fuel positions,

second actuating means in said housing and movable between first and second positions, said first and second actuating means being connected, at least during engine operation above idle speed, such that movement of said second means toward said first position moves said first means toward its maximum fuel position,

a first spring in said housing and biasing said second means toward its first position over the full range of travel of said second means,

a second spring in said housing and acting on said second means in opposition to said first spring during a portion of the travel of said second means adjacent its first position, said second spring being weaker than said first spring and acting therewith to provide a reduced spring rate for travel of said second means over said portion of such travel near its first position, and

engine speed responsive means in said housing and connected with said first and second actuating means at least during engine operation above idle speed such that said speed responsive means applies a force against said first and second means, said force increasing as a function of increased engine speed and acting in a direction opposing the bias of said first spring and, upon yielding of said first spring at a predetermined engine speed range, moving said first means toward its minimum fuel position.

Claims

1. A maximum-minimum speed limiting governor in combination with a compression-ignition engine having a fuel rack actuator for varying fuel input to the cylinders, said governor comprising a housing, first actuating means in said housing and connectible with such fuel rack actuator, said actuating means being movable between maximum and minimum fuel positions, engine speed responsive means in said housing and connected with said first actuating means, said speed responsive means being movable between maximum and minimum speed positions and arranged such that movement thereof toward said maximum speed position moves said first actuating means toward its minimum fuel position and movement of said speed responsive means toward its minimum speed position moves said first actuating means toward its maximum fuel position, support means in said housing and having a cylindrical bore with an annular abutment surrounding said bore at one end thereof, a cylindrical plunger received for reciprocating movement in said bore, said plunger having an annular flange extending axially opposite said abutment, a cap member reciprocably received within a recess in said plunger and low speed spring means in said recess and biasing said cap member outwardly therefrom and into engagement with and urging said speed respoNsive means toward its maximum speed position, said cap member having a flange stop thereon engagable with the end of said plunger to limit compression of said low speed spring and provide a non-yielding connection between said plunger and said speed responsive means at operating speeds above a preset engine idle speed, a high speed spring received on said plunger and acting between said annular flange and said housing so as to bias said annular flange toward said support abutment, and a peak load control spring acting between said abutment and said annular flange and opposing the bias of said high speed spring during the initial portion of the travel of said plunger flange away from said abutment, said speed responsive means being operable to apply a force increasing with increasing engine speed against said low and high speed springs through said cap member and plunger such that said low speed spring is partially compressed in the idle speed range and said high speed spring is partially compressed in the maximum speed range, said peak load control spring acting to reduce the maximum engine fuel input near the maximum speed range so as to maintain a relatively constant maximum engine horsepower over a range of operating speeds adjacent the maximum speed range.

2. The combination of claim 1 wherein said peak load control spring comprises an axially yieldable washer adapted to be compressed to a flat condition between said abutment and annular flange without permanent deformation of said washer.