US3757750A

US3757750A - Electronic governor for injection-type internal combustion engines

Info

Publication number: US3757750A
Application number: US00177377A
Authority: US
Inventors: Y Ohtani
Original assignee: Diesel Kiki Co Ltd
Current assignee: Bosch Corp
Priority date: 1970-09-17
Filing date: 1971-09-02
Publication date: 1973-09-11
Anticipated expiration: 1990-09-11
Also published as: DE2146507C3; FR2108264A5; DE2146507A1; DE2146507B2; SE376044B

Abstract

An electronic governor for injection-type internal combustion engines intended to electrically detect changes in revolution speed, convert the detected information into an electric control current, and therewith operate an electromagnetic actuating section; on the other hand, to similarly detect the displacement of the fuel adjusting rod, feed back the detected information temporarily to the control section through a differentiating circuit, whose time constant corresponds to the engine, thereby stabilizing the engine speed; and, furthermore, to similarly detect also each displacement of the fuel adjusting rod due to a change in engine load, feed back the detected information to the engine speed setting section, in order to provide a control performance that eliminates the engine speed regulation.

Description

United States Patent 1 [111 3,757,750 Ohtani 1 Sept. 11, 1973 [5 ELECTRONIC GOVERNOR FOR 3,651,460 3/1972 Gebelein, Jr 123/102 INJECTION TYPE INTERNAL 3,659,571 5/1972 Lang 123/102 COMBUSTION ENGINES lnventor: Yoshio Ohtani, Higashi- Matsuyama, Japan Filed: Sept. 2, 1971 Appl. No.: 177,377

Primary Examiner-Laurence M. Goodridge Attorney--Larson, Taylor and Hinds [57] ABSTRACT An electronic governor for injection-type internal combustion engines intended to electrically detect changes in revolution speed, convert the detected information into an electric control current, and therewith operate an electromagnetic actuating section; on the other hand, to similarly detect the displacement of the fuel adjusting rod, feed back the detected information temporarily to the control section through a differentiating circuit, whose time constant corresponds to the engine, thereby stabilizing the engine speed; and, furthermore, to similarly detect also each displacement of the fuel adjusting rod due to a change in engine load, feed back the detected information to the engine speed setting section, in order to provide a control performance that [30] Foreign Application Priority Data Sept. 17, 1970 Japan ..45/80999 [52] US. Cl 123/102, 123/32 EA, 123/139 E [51] Int. Cl B60k 31/00 [58] Field of Search 123/32 EA, -32 AE, 123/102, 139 E [561 References Cited UNITED STATES PATENTS eliminates the engine speed regulation. 3,407,793 10/1968 Lang 123/32 EA 3 Chin, 6 Drawing Figures 3,425,401 2/1969 Lang 123/32 EA 3,636,933 l/l972 Ohtani et al. 123/102 A r A A V 1* B I l i I l 1 J*- 1X L1 LI- u l PATENTED SE?! 1 i973 SHEET 1 HF PATENTED SHEET 2 OF 2 ELECTRONIC GOVERNOR FOR INJECTION-TYPE INTERNAL COMBUSTION ENGINES This invention relates to a fuel control device for injection-type internal combustion engines, in which the supply of fuel is controlled electronically.

In electronic fuel control devices hitherto used on injection-type internal combustion engines, particularly those employed as prime movers for electrical power generators, the on-off method of control has been the common practice to meet the need for obtaining the small speed regulation, that is, the variation in rotary speed within close limits for changes in load.

In such devices, however, the feedback mechanism has to be unnecessarily complex in construction and, though the requirements on speed control performance could be satisfied, the cost of manufacturing the device is significantly high. Because of these drawbacks, conventional devices of the kind stated above have not been suitable for use on small-size internal combustion engines.

To overcome these drawbacks, according to this invention it is now proposed to electrically detect changes in revolution speed, convert the detected information into an electric control current by the method to be made clear later, and therewith operate an electro-magnetic actuating section; on the other hand, to similarly detect the displacement of the fuel adjusting rod, feed back the detected information temporarily to the control section through a differentiating circuit, whose time constant corresponds to the engine, thereby stabilizing the engine speed; and, furthermore, to similarly detect also each displacement of the fuel adjusting rod due to a change in engine load, feed back the detected information to the engine setting section, in order to provide a control performance that eliminates the engine speed regulation.

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

FIG. l. is a block diagram of an electronic fuel control device according to this invention for internal combustion engines used for power-generator;

FIG. 2 is a circuit diagram showing one embodiment of the electronic fuel control device;

FIG. 3 is a diagram showing the waveforms of signals at various points of the circuit diagram shown in FIG.

FIG. 4 is a cross sectional view of one embodiment of the control mechanism for the fuel adjusting rod on the engine, which is connected to said electronic circuit; and

FIGS. 5 and 6 are graphs illustrating the manner in which the device according to this invention operates.

In the whole system according to the invention, as

represented by the diagram of FIG. 1, A is a sinusoidaling circuit; H, an amplifier circuit; I, a power amplifier circuit; 1, an electromagnetic control section; 0, an 05 cillator circuit; K, a circuit for detecting displacements of the fuel adjusting rod; M, a differentiating circuit; N, a speed-regulation setting circuit; and SW, a starter circuit. These components are interconnected as shown.

The network shown in FIG. 2 is a typical arrangement for the system, according to the invention, represented by the diagram of FIG. 1, Sinusoidal-wave signal generator A comprises essentially a permanent magnet I, located adjacent to a toothed-wheel magnetic body 2, which is coupled to a cam-shaft 3 of the fuel injection pump, and a detector coil 4 formed on said magnet l by winding, and electro-magnetically generates a sinusoidally varying voltage. As magnetic body 2 rotates, its teeth or protrusions move in succession past permanent magnet 1 to induce voltage in said detector coil 4. One end of the coil 4 is connected to a power-source negative conductor 5. The other end of the coil 4 is connected through capacitor C1 to the negative conductor 5 and, through capacitor C2, also to the base of transistor T1! in the saturable amplifier circuit 8. Power-source positive conductor is shown as 6. Saturable amplifier circuit B is composed of transistor T1 and resistors R1, R2, R3, and changes said induced sinusoidal voltage into a square-wave voltage by way of amplification. Monostable multivibra tor circuit C, having the revolution speed setting section, comprises transistors T2, T3, diodes D1, D2, resistors R4 through R9, inclusive, and capacitors C3, C4. This :multivibrator circuit is triggered into conductive or switched-on state when the output signal of transistor T1 in said saturable amplifier B becomes negative in polarity. Specifically, as transistor T1 starts conducting, the potential of junction point P2 between its collector and load resistor R3 drops, and this drop is differentiated by capacitor C3 and resistor R4 and applied, past the collector of transistor T2 which is currently in switched-off state, to the base of transistor T3 which is in switched-on state, thereby giving a reverse bias to the emitter and base of transistor T3 and switching off this transistor. Thereupon, charging current flows into capacitor C4 through resistor R8 and variable resistor VRI, the potential of the resistor R5 side of capacitor C4 becomes positive after a certain lapse of time, so that said reverse. bias disappears to switch on transistor T3. Thus, it is the output signal B of saturable amplifier circuit B that triggers monostable multivibrator circuit C, from whose output terminals P3 and P4 emerge square pulses Ca and C'b, respectively, equal in cyclic period to those of said signal B. The pulse lengths of square pulses Ca and Ch are equal and shown as :1 in FIG. 3. This pulse length t1 can be varied for adjustement by means of variable resistor VRl in "the revolution speed setting section. Monostable rnultivibrator circuit D is triggered by said circuit C, and monostable multivibrator circuit E is triggered by said circuit D, so that, from their respective output terminals P5 and P6, squarewave voltage signals D and E, shown in F IG. 3, of the same cyclic period T and of given pulse lengths t2 and t3 emerge. Pulse lengths II, t2 and :3 of aforementioned pulses are so selected that the sum of these lengths will be greater than the period ts for the set revolution speed. It follows therefore that, when the actual engine speed is below the set speed, the sum of t1, t2 and :3 is equal to or more than Ts. By symbols, this is expressed as 211 it :2 :3 a is. As actual speed approaches the set speed, the duration in which length tx overlaps length 153 decreases. AND circuit F detects said overlap. This circuit comprises resistor I9 and diodes D5 and D6 connected to output terminals P3 and P6 of said multi-vibrator circuits C and E, respectively, and gives out a square-wave pulse signal F from its output terminal P7. In this signal F, the length of each pulse is equal to the overlapped portion of Ca over E. Integrating circuit G, consisting of resistor R20 and capacitor C7, integrates this output pulse signal F coming from said AND circuit F and feeds the integrated signal to the amplifier circuit H which comprises transistor T6 and resistors R21 through R24, inclusive. In this amplifier circuit H, the degree of amplification is temporarily controlled by the feedback signal arriving at the emitter of transistor T6 from the fuel adjusting rod, the low-level integrated signal is amplified. Power amplifier circuit I comprises transistors T7, T8 and T9, diodes D7 through D10, inclusive, Zener diode ZD and resistors R25 through R28, inclusive. The movable coil 7 of control section J is connected to the emitter of transistor T9. The current in movable coil 7 increases as the pulse length in output signal F of AND circuit F becomes greater. This means that, when the actual speed falls further from the speed level set by means of variable resistor VR 1, in monostable multivibrator circuit C, transistor T9 becomes more conductive to increase said current.

Control section J is an electro-magnetic controller of the type described in U.S. application Ser. No. 40,793, and comprises, as shown in FIG. 4, movable coil 7, a magnetic pole 8, a cylindrical magnetic pole 9 and a permanent magnet 10. A link 11 interconnects coil 7 mechanically to fuel adjusting rod 12. A current flowing in coil 7 develops a control force proportional in magnitude to the current, in the direction perpendicular to the direction of the magnetic field according to Fleming's left hand rule. This control force is counteracted by a restoring spring 13 in controlling the position of said adjusting rod 12 in place. Oscillator circuit is a known relaxation oscillator having a uni-junction transistor T10, a capacitor C8 and resistors R29, R30, R31, and generates a gate signal for square-wave generator circuit to be described hereinafter. Detector circuit K for detecting displacements of said fuel adjusting rod is, as will be noted in FIG. 4, includes a movable core 14 detector coil 15 and, as shown in FIG. 2, transistors T11, T12, T13, T14, resistor R32 through R44, inclusive, and capacitors C9, C10. This circuit generates a square-wave pulse signal whose the pulse length corresponds to the displacement of said fuel adjusting rod. As a signal pulse from said oscillator circuit 0 arrives at the base of transistor T11 in detector circuit K, this transistor T11 switches on to introduce a potential difference across its collector resistor R33. As a result, transistor T12 becomes forwardly biased through its base and emitter and, by this forward biasing, this transistor too switches on, so that a potential difference develops across its collector resistor R36. This potential difference is fed back to the base of said transistor T11 through resistor R37. Thus, once a trigger pulse is applied to the base of transistor T1 1, both transistors T1 1 and T12 conduct and remain in conductive state while the collector potential of transistor T11 rises exponentially due to the current supplied by detector coil 15. Consequently, the base potential of transistor T12 gradually rises to reach the level of emitter potential and, upon so reaching, switches off this transistor, thereby turning off transistor T1 1. In the output voltage of detector circuit K, the pulse length is determined by the inductance of detector coil 15 when the emitter potential of transistor T12 is held at a constant level. It is this output voltage that goes to the base of transistor T13 through reistor R38 to undergo wave shaping and phase inversion before it is integrated by resistor R45 and capacitor C10. The resultant integrated voltage is applied through resistor R41 to the base of transistor T14 for amplification. The function of this part of the network is the outstanding feature of the invention and calls for particular attention. As will be noted in the graph of FIG. 5, when the input speed of the governor rises, transistor T9 in power amplifier circuit J switches off, so that the current in movable coil 7 connected to the load side decreases to reduce the control force, thereby allowing fuel adjusting rod 12 to be displaced in the direction for decreasing fuel supply by the force of restoring spring 13. This displacement increases the inductance of detector coil 15, so that transistor T14 in said detector circuit K becomes reverse-biased to shift into non-conductive state. Differentiating circuit M, having resistor R45 and capacitor C11, differentiates the output voltage of said circuit K and applies it in differentiated form to the emitter terminal of transistor T6 in amplifier circuit H. In other words, the input voltage of said transistor T6 corresponding to the revolution speed is controlled by the signal supplied by differentiating circuit M, so that transistor T9 in power amplifier circuit I switches on instantly to temporarily increase the current, which has just decreased, in movable coil 7. By this temporary increase of current, the movement of movable coil 7 in response to a change in speed is thus retarded to some extent. Conversely, when the input revolution speed falls, a chain of events similar to the foregoing one takes place to retard the movement of coil 7. This juncture explains that, even if the speed regulation should become very small, the stability of the running engine could be upheld. On the other hand, the output voltage of transistor T14 associated with the displacement of fuel adjusting rod is led to speedregulation setting circuit N, which comprises transistor T15, resistors R46, R47, R48 and variable resistor VR2. Emitter resistor R48 of this circuit N has its one end connected to resistor R8, which is in series to variable resistor VRl for revolution speed setting in monostable multivibrator circuit C. Therefore, as shown in the graph of FIG. 6, the governor characteristic, that is, the current i in control section J as a function of engine speed n is such that, when the speed-setting variable resistor VR1 is fixed while the inductance of detector coil 15 is at a value represented by V1.2, a balance exists between output power and load at point a, FIG. 6. Under this condition, should the load tend to increase, engine speed would tend to shift from point a toward b. At.this time the current in control coil 7 increases to move fuel adjusting rod in the direction for increasing fuel supply, so that transistor T14 in displacement detector circuit K switches on to develop an output signal and thereby switches transistor T15 on in circuit N, the circuit controlled by said circuit K. Consequently, resistor R8 of multivibrator circuit C becomes paralleled to transistor TlS and its'emitter resistor R48, whereby transistor T15 gets switched on. The more conductive becomes transistor T15, that is, the greater becomes engine load, the smaller will be the combined resistance of R8, R48 and T15.

In short, the speed setting changes with load. It will be understood, therefore, that a governor with zero per-cent regulation results when variable resistor VR2 in speed-regulation setting circuit N is set to bring the speed to point 0, FIG. 6, at full load. Starter circuit SW comprises resistor R49 and engine starting switch, not shown. One end of this resistor R49 is connected to the base of transistor T6 in amplifier circuit H and the other end to the positive side of the starting switch. Thus, turning on the starting switch sets the starter motor in motion to crank the engine and, at the same time, switches on transistor T6, because this transistor becomes forward-biased through reistor R49. As transistor T6 begins to conduct, transistors T7, T8 and T9 become conductive, so that the control current in said movable oil 7 rises. The increased control current persists as long as the engine starting switch is on.

The circuit arrangement and functions described thus far will be re-considered from the viewpoint of engine control.

Turning on the starting switch increases the control current, as explained above, in said movable coil 7 of the electro-magnetic fuel control mechanism, so that fuel adjusting rod 12 will shift to the position for maximum fuel supply. This condition facilitates the firing up of the engine in starting. As the engine picks up speed after starting up and goes up to and above the speed level set by means ofvariable resistor VRl in said circuitC, the control current in movable coil 7 decreases until the output power of the engine balances with its current partial load to settle the engine revolution speed. As the speed falls under this condition due to a rise in load, the pulse overlap in AND circuit F expands to increase the output current of power amplifier circuit I, thereby increasing the control force and therewith shifting fuel adjusting rod 12 in the direction for increasing fuel supply. At this connection, the speedregulation setting circuit N functions to shift the speed setting in the rising direction, making the speed regulation smaller, regardless of the current setting of said varaible resistor VRl, so that output power now balances with load. Conversely, a reduction in load gives rise to a chain, similar to the above, of events in reverse sense to effect a similar governor action.

When it is desired to increase engine output power, variable resistor VRl is to be re-adjusted to the position for a smaller ohmic value. This repositioning will allow the governor to perform the same action as above, with the engine developing greater output power. If it is desired to alter the speed regulation, variable registor VR2 in speed-regulation setting circuit N is to be readjusted. The hunting phenomenon, which is generally liable to occur under small speed regulation, is totally eliminated in the present device because the displacement, if any, of fuel adjusting rod 12 is detected to produce a signal, which is then differentiated and fed back temporarily. It will be seen from the fore going description that the device according to the invention is characterized by its three feedback schemes for accomplishing the desired ends. Also, in the present control circuit, the revolution at overspeed of the engine upon the fault of the circuit may be avoided. if there is occurred the fault which results in that the pulses t1 :4 are not obtained, e.g. the disconnecting of detector coil 4, in this control circuit, no fuel is supplied to the engine and thus the overspeed revolution of it can be avoided because the fuel supply is performed in proportion to the pulse lenght of output pulses.

While the invention has been described with respect to the illustrated embodiment thereof it is to be understood that various changes and modifications may be made without departing from the spirit and scope of the invention, and it is intended, therefore, to cover all such changes and modifications in the appended claim.

What is claimed is:

1. An electronic governor for a fuel injection type internal combustion engine, said governor comprising a first monostable multivibrator circuit for generating a pulse output in accordance with the rotational speed of the engine and a selected speed setting, a second monostable multivibrator circuit triggered responsive to the output of said first monostable multivibrator circuit, a third monostable multivibrator circuit triggered responsive to the output of said second monostable multivibrator circuit, an AND gate having first and second inputs respectively connected to the outputs of said first and third monostable multivibrator circuits, integrator and amplifier means for integrating and amplifying the output of said AND gate circuit, and means responsive to the output of said integrator and amplifier means for controlling positioning of a fuel regulating rod.

2. An electronic governor as claimed in claim 1 further comprising oscillator circuit means the output frequency of which is varied responsive to the displacement of the fuel regulating rod and means for connecting the output of said oscillator circuit means to control the output of said integrator and amplifier means.

3. An electronic governor as claimed in claim 2 further comprising means for connecting the output of said oscillator circuit means to control the speed setting of said first monostable multivibrator circuit.

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