US3750633A

US3750633A - Electronic governor for fuel-injection type internal combustion engines

Info

Publication number: US3750633A
Application number: US00122473A
Authority: US
Inventors: Y Ohtani; T Kakijiama
Original assignee: Diesel Kiki Co Ltd
Current assignee: Bosch Corp
Priority date: 1970-03-14
Filing date: 1971-03-09
Publication date: 1973-08-07
Anticipated expiration: 1990-08-07
Also published as: JPS4946003B1

Abstract

An electronic governer for fuel-injection type internal combustion engines in which the speed regulation and ''''ungleich'''' effect may be achieved by means of control circuit and ''''ungleich'''' setting circuit, and there may be obtained a stable engine output characteristic for the full range of engine speeds from the low- speed to the high- speed by providing antioverrun circuit and anti-hunting circuit, so that the possibility of hunting under low-speed operating conditions is completely avoided.

Description

United States Patent 1191 1111 3,750,633 ()htani et a1. 1 Aug. 7, 1973 [S4] ELECTRONIC GOVERNOR FOR 3,630,177 12/1971 123/32 EA FUEL-INJECTION TYPE INTERNAL COMBUSTION F E Pi 3:372:680 3/1968 Schoil.....................:.:::.:: tbs/3212A [75] Inventors: Yoshio Ohtani, Higash i I g: :i: g%% Primary Examiner-Laurence M Goodridgje p Attorney-'Larson, Taylor & Hinds 731 Assignee: Diesei Kiki Kabhsiiiiikfisii,

Tokyo,Japan 221 Filed: Mar. 9, 1971 [57] ABSTRACT 2 122,473 An electronic governer for fuel-injection type internal 7-7m v r combustion engines in which the speed regulation and Foreign Application Priority Data ungleich" effect may be achieved by means of control Mar, 4 7 Jap n 45 R121 5 circuit and ungleich setting circuit, and there may be obtained a stable engine output characteristic for the [52] U.S. Cl 123/102, 123/140 MC full range of engine speeds from the lowspeed to the [51 Int. Cl. F02d 11/10 highspeed by providing anti-overrun circuit and antii58l Field 01 Search 123/32 15A, 102, 140 MC, hunting circuit, 110 that the possibility of hunting under l23/I3) E iow-spced'opcrating conditions is completely avoided.

i561 Reierences Cited 4 Claims, 7 Drawing Figures UNITED STATES PATENTS 3,659,571 5/1972 Lang 123/102 PATENTEL 7 I975 (Tis) Vmox PATENTED AUG 7 I975 SHEE120F3 ELECTRONIC GOVERNOR FOR FUEL-INJECTION TYPE INTERNAL COMBUSTION ENGINES This invention relates to an electronic governor for fuel-injection type internal combustion engines.

Electronic circuits in governors of this type have heretofore produced an output current for actuating an electromagnetic mechanism to control the fuel regulating rod, according to whose position the fuel injection pump delivers more or less fuel to the engine. Said output current is produced by first applying the output voltage of an oscillating circuit to a monostable multivibrator of a known type. Said oscillator consists of a capacitor and a variable inductance whose inductance value corresponds to the position of the accelerator lever. The output voltage of said multivibrator is then integrated by an integrating circuit and comes out as a DC voltage. On the other hand, a signal is generated by an electromagnetic mechanism coupled to the rotating shaft of the fuel injection pump. This signal, corresponding to the rotational speed of the engine, is applied to a monostable multivibrator of a known type, whose output voltage is then integrated by an integrating circuit and therewith converted into a DC voltage. This DC voltage is compared against the other DC voltage mentioned above to produce the afore-mentioned output current, which is proportional to the difference between said two DC voltages and which is used to actuate the electromagnetic mechanism as stated. In this method, the former DC voltage'is proportional to the frequency of the oscillating circuit, whereas the latter DC voltage is proportional to the rotational speed of the engine, so that the resultant control output current as a function of the rotational speed of engine generally takes a constant gradient over the entire range of engine speeds. In other words, the speed regulation of the engine is constant for the entire speed range from lowspeed region to high-speed region. Although a smallv speed regulation is generally desired of the engine, the regulation in the low-speed region needs to be set relatively high with a view to preventing the engine from hunting. Because of this requirement, it has been proposed to feed integrated pulse signals from the input and output of said monostable multivibrator to a differential amplifier circuit in order to change the degree of conduction through a transistor according as the output voltage of said differential amplifier stays below or rises above a certain fixed value, whereby the speed regulation for the low-speed region will differ from that for the high-speed region, but such circuits have failed to satisfy the requirement fully.

An object of this invention is to provide an improved electronic governor for fuel-injection type internal combustion engines including a circuit means by which the frequency of oscillator circuit is caused to change in accordance with the displacement of fuel regulating rod, thereby expanding the speed regulation for the low-speed range of the engine in order to avoid engine hunting" when the engine is running in that range of speeds.

Another object of this invention is to provide an improved electronic governor for fuel-injection type internal combustion engines including a circuit means which is connected in parallel with the comparison circuit for comparing the output voltage of the oscillator circuit with another output voltage proportioned to the rotational speed of the engine, and which is arranged to produce an output signal in proportion to the rotational speed of the engine or the position of accelerator lever, the output voltage of which is superimposed on the output voltage of the comparison circuit thereby obtaining the ungleich" effect.

A further object of this invention is to provide novel and improved electronic governor for fuel-injection type internal combustion engines in which the speed regulation and ungleich effect may be achieved by means of a control circuit and ungleich" setting circuit, and there may be obtained a stable engine output characteristic for the full range of engine speeds from the lowspeed to the highspeed by providing antioverrun circuit and anti-hunting circuit, so that the possibility of hunting under low-speed operating conditions is completely avoided.

In order that this invention may be more readily understood, a preferred embodiment of this invention will now be described, by way of example only, with reference to the accompanying drawings in which:

FIG. 1 is a block diagram for an electronic governor according to this invention for fuel-injection type internal combustion engines;

FIG. 2 is a circuit diagram representing a preferred embodiment of this invention;

FIG. 3 is a graph showing the output curves derived from the circuit of FIG. 2',

FIG. 4 is similar to the graph of FIG. 3 but refers to a conventional electronic circuit;

FIG. 5 is a longitudinal cross section showing a control section according to this invention as installed on a fuel injection pump;

FIGS. 6 and 7 both graphs showing output curves available from the electronic circuit arranged to this invention.

Referring to the block diagram of FIG. 1, A is a constant-voltage circuit. Output voltage of oscillator circuit 8" is passed onto Schmitt circuit C, and is then fed through differential circuit D" and detector circuit E" to monostable multivibrator circuit F. Said multivibrator circuit F delivers its output voltages to voltage comparison circuit l-I," on the one hand, through integrating circuit G and to feedback circuit 1 on the other hand. Output voltage of circuit I is fed back to said oscillator circuit B. One of the two output voltages coming out of electromagnetic rotary voltage. converter circuit I(" is amplified by amplifier circuit L" and is led to monostable multivibrator circuit 0" through differential circuit "M" and detector circuit N. Multivibrator circuit 0" gives its output voltage to said voltage comparison circuit I-I" through integrating circuit P," and outputvoltage of comparison circuit H is fed to fuel regulating rod control circuit R through amplifier circuit Q." The other output voltage developed by integrating circuit P" is led to said circuit 0" through ungleich" set ting circuit T." The other output voltage of electromagnetic rotary voltage converter circuit K"'is led to said fuel regulating rod control circuit R through an- 4 ti-overrun circuit 8. The signal emerging from circuit R is fed back to said converter circuit K through the engine U. Thus, a closed loop is formed by these component circuits.

In FIG. 2, T, through T are transistors; D, through D,,, diodes; C, through C capacitors; R, through R resistors; VR, through VR-,, variable resistors; VL,, a variable inductance associated with the position of accelerating lever of the internal combustion engine; VL a variable inductance associated with the position of fuel regulating rod, VL a movable coil in fuel regulating rod control mechanism for moving the fuel regulating rod of the fuel injection pump in accordance with the output current produced by the electronic circuit network; r,, a relay; 1, a positive conductor; and 2, a negative conductor.

The circuits named above will be functionally described by referring to the same FIG. 2. Circuit A is a known constant-voltage circuit using a Zener diode and utilizing the Zener characteristic. Circuit B is an oscillator including transistor T resistors R through R variable inductance VL and capacitors C C The oscillating frequency is varied by varying the inductance of VL,, whose coil has a core. This variation is accomplished by coupling said core to the accelerator lever. The sinusoidal output voltage of oscillator 8" is led to Schmitt circuit C comprising transistors T T and resistors R, through R and is changed thereby to a square-wave pulse signal. Differenctial circuit D," formed by resistor R, and capacitor C forms, out of the square-wave signal coming from circuit C, a trigger pulse signal, which enters detector circuit E to be changed thereby to a negative trigger pulse signal. This negative trigger pulse signal is transformed into a consta'nt-width square-wave pulse signal by monostable multivibrator circuit F" comprising transistors T T load resistorsR R bias resistor R,,,; base resistor R,,,; time-constant setting resistor R and capacitor C The output signal of .multivibrator F undergoes integration in integrating circuit G comprising resistor R and capacitor C and comes out of circuit-G as a DC voltage proportional to the pulse density representing the position of the accelerator lever. This DC voltage is fed into one of the inputs of comparison circuit H. v

Electromagneticrotary voltage converter circuit K comprises an assembly of permanent magnet 3 and detector coils 3a, 3b, which is located close to a toothedwheel magnetic body 4a coupled to injection-pump camshaft 4. Rotation of body 40 induces voltage in detector coils 3a, 3b wound on permanent magnet 3 as the teeth or peripheral protrusions of body 4a move in succession past the permanent magnet. Voltage induced in this manner in coil 3a is applied for amplification to amplifier circuit L" comprising transistor T capacitors C C and resistors R through R The amplified voltage signal undergoes differentiation in differentiation circuit M" comprising capacitor C and resistor R and emerges as a trigger pulse signal, which is then detected by detector circuit N having diode D Detector N" eliminates positive pulses from this signal, so that a negative trigger pulse signal appears from its output and applies to monostable multivibrator circuit O," wherein it is transformed into a constant-width square-wave pulse signal. Circuit 0 is constituted by transistors T T load resistors R R bias resistor R base resistor R capacitor C time-constant setting resistor R and capacitor C The output signal of multivibrator 0" is finally converted into a DC voltage proportional to the rotational speed of the engine by integrating circuit P" having resistor R and capacitor C,,. This DC voltage is the other input signal of said voltage comparison circuit iHIDS Comparison circuit H" is constituted by transistors T T resistors R through R and R through R and variable resistor VR Emitters of transistors T and T are both connected to negative conductor 2 through resistor R Transistor T, has its collector connected to positive conductor 1. Transistor T has its collector connected to positive conductor 1 through resistor R Resistors R R and variable resistor VR serve as a bias resistance for use in setting the operating point of transistor T changing ohmic value of VR for adjustment changes the operating point tochange the rotational speed of the engine in idling condition. in comparison circuit H, the output signal of said oscillator circuit B, varying with variable inductance in this circuit, applies to the base of transistor T to switch on this transistor, thereby admitting current into resistor R Consequently, the potential of the emitter of transistor T rises in proportion to the voltage change representing a displacement of said accelerator lever, thereby making transistor T less conductive than before. In other words, the case of conduction through transistor T varies with the output voltage of integrating circuit P, which is proportional to said rotational speed of the engine, but the difficulty of conduction varies with the output voltage of oscillator circuit 8" which is proportional to the position of accelerator lever, represented by L through L in FIG. 3. The output voltage of circuit H, being therefore representative of the difference between the two voltage signals, is next amplified by circuit .Q having variable resistor VR for setting speed regulation. it is by this resistor that the input voltage of transistor T is controlled to vary the rate of change (or gradient of the curve) in output voltage for changes in the rotational speed of engine as indicated by dotted lines L through L in FIG. 3. Since the output voltage of transistor T- applies to movable coil VL of the fuel regulating rod control mechanism, said rate of change determines the speed regulation of the engine. Resistor VR; is to be so set as to'provide the smallest possible regulation not entailing the'possibility of engine hunting, for a small regulation is generally desirable in applications. Once so set, resistor VR is very unlikely to require a change of its setting later. The DC output voltage of integrating circuit P, proportional to the rotational speed of the engine, is led through a branched path to the collector of transistor T in amplifier circuit Q," through ungleich" setting circuit T" comprising variable resistors VR VR transistors T T,,,, resistors R through R and diodes D-,, D,;. it follows that a rise in the rotational speed of engine raises the base potential of transistor T to switch on thistransistor and, while it is conducting, the base potential of transistor T is down, so that the collector current of this transistor is low. This decreased collector current in turn decreases the collector current of transistor T in amplifier circuit "Q." Therefore, the output current of power amplifier circuit R decreases, as representedby line VR in FIG. 3, to effect so-called ungleich action on fuel supply.

It is possible to make a setting at any point, as desired, between the lines VR, and VR' in FIG. 3 by means of variable resistor VR i, in circuit T. Similarly, the gradient of the 'ungleich" curve can be varied at will between the lines VR, and VR., as shown in FIG. 3, by means of variable resistor VR,. A word on the meaning of ungleich here may be in order: this term refers to the fact that, in an internal combustion engine,

the amount of air the engine draws for each intake stroke of the piston decreases as the rotational speed of engine rises, and means the automatic action calculated to decrease or lower the maximum fuel supply to the engine cylinders progressively from low to high over the range of engine speeds.

The feedback circuit l" according to this invention will now be described. Detector coil VL. for sensing the position of fuel regulating rod is electrically connected in series to coil VL of oscillator circuit B," and the core of this coil is mechanically connected with fuel regulating rod 5 as shown in FIG. 5. A change in inductance of detector coil VL therefore affects the oscilating frequency of circuit "B." Thus, when hunting" occurs, the fuel regulating rod will rock to and fro; in this rocking motion, suppose the fuel regulating rod displaces itself in the direction for increasing fuel supply. The oscillator frequency will then rise in circuit 8" to increase the current flowing in movable coil VL in the injection-pump fuel regulating rod control mechanism, so that the fuel regulating rod 5 displaces subsequently in the direction for increasing supply.

if the fuel regulating rod 5 in rocking motion moves in the direction for decreasing fuel supply, a chain of events opposite in sense to those mentioned above takes place. This is because, as will be noted in the block diagram of FIG. 1, the signal in fuel regulating rod control circuit "R" is fed back through the circuits HU'1IlbK,l1HL"7HM,H uNn no," P, "H" nd Q. and also through the other loop formed by 'l," "B," NC," ttDn E's! up," HG," HI, and no." not i cluding circuit U" (engine), which minimizes the time delay in the flow of signal to stabilize the engine speedily.

By this feedback signal, the speed regulation in lowspeed region can be made wider to minimize the possibility of hunting, as will be later seen. The output current of power transistor T used in said control circuit "R" is derived from the difference in output voltage between transistors T, and T in comparison circuit l-l." Therefore, assuming a given position of accelerator lever, a rise in rotational speed of engine due to a fall in engine load will move fuel regulating rod 5 in the direction for decreasing fuel supply, causing the core to be pushed into said coil VL, and thereby increasing its inductance. Hence the oscillating frequency of circuit 8" will fall to raise the output voltage of transistor 7 in comparison circuit H." For this reason, the difference between said two output voltages diminishes to raise the rotational speed of engine, whereby the control output current is increased until the engine output power balnces with engine load. In FIG. 6, this relation is illustrated by curves plotted in a graph with the output voltage of transistor T (collector voltage v.) taken on the vertical axis and the rotational speed of engine "N" taken on the horizontal axis, the parameters being the emitter voltages of transistors T and T in the absence of a feedback signal arising from detector coil VL control output voltage V,., is obtained at engine speed N with parameter T as will be noted in FIG. 6, but, when a feedback signal occurs, it will be seen that output voltage of transistor T comes into play to produce control output voltage V at engine speed N This relation means a widening of speed regulation. Similarly, for falling engine speed, V will not be avilable unless the engine speed goes down from N, to N,. The feedback signal need to be eliminated if the speed regulation has to be small in the normal load and speed ranges. To meet this requirement, such an arrangement is included in the circuit network according to this invention as will remove the signal when the running engine is accelerated by means of the accelerator lever. In this arrangement to be explained hereunder, the output voltage of monostable multivibrator circuit F is integrated by means of resistor R and capacitor C and the integrated voltage signal is applied to the input of transistor T This input voltage varies with the position of the accelerator lever, so that, as the lever is moved in the direction for increasing fuel supply, the base potential of transistor T, rises to switch on this transistor. According as transistor T is more or less conductive, transistor T similarly conducts more or less to decrease the current flowing in coil V1. thus eliminating the feedback signal. Thus, moving the accelerator lever in the direction for decreasing fuel supply,the base potential of transistor T, falls to switch off this transistor and also transistor T so that a current flows in coil VL, to lntroduce a feedback signal.

Anti-overrun circuit S will next be considered. This circuit is a known Schmitt circuit, whose input receives voltage from coil 3b of electromagnetic rotary detector circuit K." With the power-source voltage applying between positive conductor 1 and negative conductor 2, transistor T becomes conductive on ac-- count of dividers R and R to energize the coil of relay r connected to the collector of transistor T This energization closes, in relay r,, contact r which is connected to the input side of movable coil VL, in the fuel regulating rod control mechanism. As engine speed rises to and over the maximum level, the basepotential of transistor T rises to switch this transistor on, so that, in turn, the base potential of transistor T falls to switch this transistor off, thereby interrupting, in relay r,, the excitation current flowing in the relay coil, which is connected to the collector of transistor T This interruption opens said contact r, in relay r, to shut off the current flowing in said movable coil'Vl. to allow the fuel regulating rod 5 to shift, under the urging force of spring 6, in the direction for decreasing fuel supply, thereby preventing any abnormal rise of engine speed. Fuel regulating rod 5 is constantly urged by spring 6 in said direction so that, even when the control circuit network fouls up for one reason or another to become inoperative, no overrunning condition of the engine can occur; the engine is prevented from overrunning and will stop running by itself.

The governor actions described thus far will be viewed again but in relation to the control of the engine.

Turning on the starter switch initiates the flow of current in movable coil VL, to shift fuel regulating rod 5 to the position QM: of fuel supply, FIG. 7. With the rod in this position, the engine fires up more easily. Upon starting up, suppose the engine is carrying a steady partial load represented by point 5,, FIG. 7: if the load decreases under this condition, the engine speed rises as limited by the speed regulation there. Consequently, the pulse density in the output pulse signal of detector circuit K" applying to monostable multivibrator circuit "0" increases to raise the output voltage of integrating circult P." This raised output voltage decreases the output current of power amplifier circuit Q, whereby the excitation current in movable coil VL decreases to allow the fuel regulating rod to be pulled back in the direction for decreasing fuel supply until engine output power balances with the load at point 5,, FIG. 7. Conversely, an increase of load in the above-mentioned condition of the engine results in a chain of similar events opposite in sense to what has just been described, thereby moving the fuel regulating rod in the direction until the system resumes another balanced state.

When it is desired to increase the engine output power during normal operation, the usual practice is to move the accelerator. When the accelerator lever of oscillator circuit B is moved to change the inductance of VL,, the excitation current flowing in movable coil VL increases, so that the fuel regulating rod will move in the direction until point 8;, (FIG. 7') is reached. There may be cases in which a smaller speed regulation is desirable. In such a case, the setting of variable resistor VR is to be brought down to a lower value to obtain a modified characteristic curve represented by the dotted line VR',. if a greater un'gleich" effect is desired, the line VR is to be repositioned to shift the gradient of the curve to the dotted line VR',,, and the line VR is to be repositioned to bring the operating point to the dotted line VR 7 From the foregoing description, the excellence of the governor according to this invention will be noted to lie in that the governor permits both thespeed regulation and the "ungleich" effect to be adjusted, includes a new and anti-overrun circuit and an anti-hunting circuit and therefore assues a stable engine output characteristic for the full range of engine speeds from the lowspeed to thev high-speed region, and that the governor in given an added function of completely eliminating the possibility of hunting under low-speed operating conditions.

While this invention has been described in detail with respect to its preferred embodiment it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of this invention and it is intended, therefore, to cover all such changes and modifications in the appended claims.

What is claimed is:

1. An electronic governor for a fuel-injection type internal combustion engine, comprising variable frequency oscillator means for producing a first, reference signal, means for generating asecond, d.c. voltage signal related to the rotational speed of the engine, comparison circuit means for comparing the signal produced by said oscillator means and said d.c. voltage signal produced by said generating means, and for producing a control signal in accordance therewith, fuel regulating rod control means for controlling the displacement of the fuel regulating rod, means, including a power amplifier circuit, for connecting the control signal output of said comparison circuit means to said fuel regulating rod control means, and feedback circuit means responsive to the position of the fuel regulating rod for controlling the frequency of said variable frequency oscillator circuit means in accordance with the displacement of the fuel regulating rod, said power amplifier circuit including means for setting the speed regulation provided by the governor and said governor further comprising means responsive to a signal related to? said d.c. voltage signal for decreasing the current output of said power amplifier-circuit in response to an in crease in the rotational speed of the engine so as to am tomatically decrease the fuel supply to the engine prog-j,

gressively from low to high over the engine speed range.

of the accelerator operating lever.-

3. An electronic governor as claimed in claim 1 wherein saidfuel regulating rod controlmeans includes an electromagnetic control coil, said governor further comprising anti-overrun circuit means for providing a stable engine output characteristic over the full engine speed range and comprising relay 'means responsive to said d.c. voltage signal for terminating the current flow to said electromagnetic control coil when the engine speed reaches a predetermined value so that the fuel regulating rod moves in a direction to decrease the fuel supply to the engine.

- 4. An electronic governor for a fuel-injection type internal combustion engine, comprising variable frequency oscillator means for producing afirst, reference signal, means for sensing engine rotational speedand for generating a second, d.c. voltage signal the magnitude of which is related to the rotationalspeed of the engine, comparison circuit means for comparing said first signal produced by said oscillator means and said d.c. voltage signal produced by said generating means and for producing a control signal in accordance therewith, electromagnetic fuel regulating rod control means for controlling the displacement of the fuel regulating rod, means for connecting the control signal out put of said comparison circuit means to said electromagnetic fuel regulating rod control means, circuit means responsive to the position of the fuel regulating rod for controlling the frequency of said variable frequency oscillator circuit means in accordance with the displacement of said fuel regulating rod, and antioverrun circuit means for providing a stable engine output characteristic over the full engine speed range and comprising relay means responsive to said dc. voltage signal for terminating the current flow to said electro' magnetic control means when the engine speed reaches a predetermined value so that the fuel regulating rod moves in a direction to decreasethe fuel supply to the engine, said connecting means including power amplifier circuit means including means for setting the speed regulation provided by the governor, and said governor further comprising means responsive to a signal related to said d.c. voltage signal for decreasing the current output of said power amplifier circuit means in response toan increase in the rotational speed of the engine so as to automatically decrease the fuel supply to the engine progressively from low to high over the engine speed range.

* it i

Claims

1. An electronic governor for a fuel-injection type internal combustion engine, comprising variable frequency oscillator means for producing a first, reference signal, means for generating a second, d.c. voltage signal related to the rotational speed of the engine, comparison circuit means for comparing the signal produced by said oscillator means and said d.c. voltage signal produced by said generating means, and for producing a control signal in accordance therewith, fuel regulating rod control means for controlling the displacement of the fuel regulating rod, means, including a power amplifier circuit, for connecting the control signal output of said comparison circuit means to said fuel regulating rod control means, and feedback circuit means responsive to the poSition of the fuel regulating rod for controlling the frequency of said variable frequency oscillator circuit means in accordance with the displacement of the fuel regulating rod, said power amplifier circuit including means for setting the speed regulation provided by the governor and said governor further comprising means responsive to a signal related to said d.c. voltage signal for decreasing the current output of said power amplifier circuit in response to an increase in the rotational speed of the engine so as to automatically decrease the fuel supply to the engine progressively from low to high over the engine speed range.

2. An electronic governor as claimed in claim 1 further comprising override means for overriding said feedback circuit means in accordance with the position of the accelerator operating lever.

3. An electronic governor as claimed in claim 1 wherein said fuel regulating rod control means includes an electromagnetic control coil, said governor further comprising anti-overrun circuit means for providing a stable engine output characteristic over the full engine speed range and comprising relay means responsive to said d.c. voltage signal for terminating the current flow to said electromagnetic control coil when the engine speed reaches a predetermined value so that the fuel regulating rod moves in a direction to decrease the fuel supply to the engine.

4. An electronic governor for a fuel-injection type internal combustion engine, comprising variable frequency oscillator means for producing a first, reference signal, means for sensing engine rotational speed and for generating a second, d.c. voltage signal the magnitude of which is related to the rotational speed of the engine, comparison circuit means for comparing said first signal produced by said oscillator means and said d.c. voltage signal produced by said generating means and for producing a control signal in accordance therewith, electromagnetic fuel regulating rod control means for controlling the displacement of the fuel regulating rod, means for connecting the control signal output of said comparison circuit means to said electromagnetic fuel regulating rod control means, circuit means responsive to the position of the fuel regulating rod for controlling the frequency of said variable frequency oscillator circuit means in accordance with the displacement of said fuel regulating rod, and anti-overrun circuit means for providing a stable engine output characteristic over the full engine speed range and comprising relay means responsive to said d.c. voltage signal for terminating the current flow to said electromagnetic control means when the engine speed reaches a predetermined value so that the fuel regulating rod moves in a direction to decrease the fuel supply to the engine, said connecting means including power amplifier circuit means including means for setting the speed regulation provided by the governor, and said governor further comprising means responsive to a signal related to said d.c. voltage signal for decreasing the current output of said power amplifier circuit means in response to an increase in the rotational speed of the engine so as to automatically decrease the fuel supply to the engine progressively from low to high over the engine speed range.