DE2107371A1 - Fuel control system - Google Patents

Description

PATENT Attorneys .. '.:': 2107371 Dipi.-chem. Dr. D. Thomsen Dipi.-mg. H. Tiedtke
Dipi.-chem. G. Bühling oipt.-mg. R. Kinne MUNICH tS
KAISER-LUDWIQ-PLATZ
TEL. 0 * 11/530211
530212
CABLES: THOPATENT
TELEX: FOLQT Dipi.-mg. W. Weinkauff FRANKFURT (MAIN) 50
FUCHSHOHL 71
TEL. 0S11 / S1 <WM

Reply requested to: Please reply to:

8000 some 15 February 16, 1971

Nippondenso Kabushiki Kaisha Kariya-shi (Japan)

and

Toyota Jidosha Kogyo Kabushiki Kaisha Toyota-shi (Japan)

Fuel control system

The invention relates to fuel control systems having a distributor type fuel injection pump, and more particularly on a power control system in which the fuel supply by an electromagnetic on-off valve operated in accordance with timing pulses from an electrical control circuit is controlled.

In fuel control systems with common rail fuel injection tracks a mechanical regulator is used in which the fuel supply to a plunger pump

Oral agreements, especially by telephone, require written confirmation Bank (Munich) Account 100103 · Deutsche Bank (Munich) Account 21/39231 ■ Vereinsbank (Munich) Account 3313M · Hypo-Banfc (Munich) Account 3I121SS

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by changing the cross-sectional area of the fuel passage to the inlet port of the plunger pump in accordance with FIG Position of an inlet throttle valve is controlled by the centrifugal weight coupled to the pump drive shaft centrifugal force exerted on it and the spring force of a governor spring is determined.

To achieve an engine characteristic compliant However, fuel control characteristics must be one in such conventional fuel control systems with a mechanical regulator empirical adjustment of the controller components can be made. In addition, it is extremely difficult to obtain highly precise conformity of the fuel control map for any given engine map to reach.

The invention provides a fuel control system which has one plunger pump, the single one Plunger for distributing and pushing out the fuel while rotating and at the same time reciprocating the plunger, owns an electromagnetic valve control circuit with a control voltage generator for generating a control voltage representing an engine operating condition and a one-shot timer circuit for generating timing pulses whose pulse width is in accordance with the control voltage is determined, and an electromagnetic valve in the leading to the inlet port of the plunger pump Fuel line is provided and in on-off operation for

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Determining the amount of fuel that is admitted in accordance with the pulse width of the timing pulses works.

According to the invention, the fuel control is achieved by an electromagnetic valve which is provided in the fuel line leading to the inlet port of the plunger pump and which operates in on-off mode in accordance with time pulses whose pulse width is in accordance with an engine operating condition via a control circuit for the electromagnetic valve is changed to control the amount of fuel supplied to the plunger pump which distributes the supplied fuel to fuel injection nozzles provided in the respective engine cylinders, thus controlling the fuel injected into each cylinder. It is different from the mechanical governor of the conventional distributor type fuel injection pump ^; used fuel control system possible, the fuel | Control characteristics can be easily preset in accordance with the engine parameters. In addition, increased accuracy of fuel control to meet engine requirements can be ensured. Furthermore, the fuel control characteristic can be changed simply by changing the control voltage characteristic of the control voltage generator in controlling the electromagnetic valve, for example, by adjusting a variable element such as a variable resistor.

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The invention is illustrated in the following with the aid of a schematic Drawings of exemplary embodiments explained in more detail.

Fig. 1 shows a sectional view substantially the mechanical parts of a preferably selected embodiment of the invention Figure 3 illustrates a fuel control system additionally showing in block form an electromagnetic control valve;

Fig. 2 shows a circuit diagram of the controller

of the electromagnetic valve together with a sectional view of the electromagnetic Valve;

3 shows a graph of the control voltage characteristics the control voltage generator;

Fig. 4 is a diagram showing the relationship between the temporal width of the monostable Timing circuit represents generated timing pulses and the control voltage;

Fig. 5 shows an arrangement of inlet and outlet channels in the pump plunger and a distributor drum the plunger pump; and

Fig. 6 is a graph showing the fuel control characteristics of the fuel control system according to the invention.

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In Fig. 1, the reference numeral 1 denotes an electromagnetic valve. It is in the closed state
with no current through its solenoid coil 11
flows. In this state of the valve, a valve head 14 formed on the lower end of a movable iron core 13 is pressed against a valve seat 15 by the restoring force
a spring device 12 held, whereby the valve is closed- 'j sen. With the electromagnetic valve 1 thus closed, the fuel, which is at a constant pressure of several atmospheres, cannot pass through a valve inlet 10
reach. If the solenoid coil 11 is energized when a time pulse voltage from a control circuit 2 for the electromagnetic valve (described in detail below) is applied to it, the electromagnetic attraction force overcomes the spring force of the spring 12 and moves the iron core 13 upwards, releasing the valve head 14 from the valve seat 15 and thus opens the valve 1. In this state of the valve, the fuel | left through valve 1 on the valve inlet 10 side. When the solenoid coil 11 is deenergized, the time pulse from the control circuit 2 for the electromagnetic valve disappears, the movable iron core 13 is moved downwards by the restoring force of the spring 13 and brings the valve head 14 into contact with the valve seat 15, whereby the flow of fuel from the valve inlet IO is cut off. As long as the delay in the action of the electromagnetic valve 1 is negligible, the changes

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Amount Q ^ of the fuel passed therethrough substantially proportional to the pulse width T of the timing pulse voltage applied to the solenoid coil 11, where Q = Q (Q _m is the minimum amount of fuel) when T = T (T is the minimum pulse width), and Q = Q., (Q _M is the maximum amount of fuel) when T = T ^ (T _M is the maximum pulse width).

The control circuit 2 for the electromagnetic valve generates timing pulses, the width of which varies in accordance with various engine operating parameters to meet given Hotor operating requirements changes.

Fig. 2 shows in detail the control circuit 2 for the electromagnetic valve. It has a control voltage generator 21, a one-shot timer circuit

22, a current amplifier 23 and a trigger signal generator 46.

The control voltage generator 21 generates a control voltage that changes in accordance with engine operating variables such as the engine speed and the amount of operation of a fuel control device (for example, the amount of depression of the accelerator pedal). In this embodiment , the fuel control is to be achieved at full load and part load, which is the most essential function for diesel engines; such critical control functions as the

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Fuel increase when starting the engine and the correction the maximum amount of fuel to be injected in low-speed and high-speed operation are omitted. The generator 21 has a Uotordrepeedometersdetektor 26, which is an alternating current generator with a rotor, which rotates with rotates at a constant speed ratio to the engine cube shaft. Its output voltage is rectified by a rectifier diode 27 J and by one of capacitors 23 and 29 and a resistor 30 formed smoothing circuit. The smoothed voltage is determined by »Inen voltage divider 31 divided to provide a DC voltage (hereinafter referred to as motor speed voltage VS) at points A and B, which is proportional to the engine speed. A voltage divider 32 determines the actuation quantity of a fuel control device, such as the amount of depression

of the accelerator pedal, and supplies a corresponding direct voltage (hereinafter referred to as B = pull voltage VF) between point .Ί A and a ground point Έ. Furthermore, a transistor 34 is provided, the base of which is connected to a point B via a constant voltage diode 33 and the emitter and collector of which are connected to corresponding resistors 35 and 36, respectively. If the forward voltage drop at the base-emitter junction of transistor 34 is neglected, the sum of the motor speed voltage VS at points A and B and the reference voltage VF at points A and E is applied to the base of transistor 34 via constant voltage diode 33 . If the voltage drop across the constant voltage diode 33 is denoted by Vz and

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when VS + VP = Vz, no forward bias (turn-on voltage) is applied to the base of transistor 34, which therefore carries no current. At this time, the control voltage Vc at point C takes a maximum value Vc. When VS + VF = Vz, a forward bias voltage equal to the difference between (VS + VP) and Vz is applied to the base of transistor 34, thereby causing collector current. At this time, the control voltage Vc at the point C takes an appropriate intermediate value between the maximum value Vc _r and the minimum value Vc. The minimum control voltage Vc results when the transistor 34 is completely in the conductive state. The voltage between points C and E, that is, the control voltage Vc, changes in accordance with engine operating parameters such as the engine speed N and the degree of release 0 (amount of depression) of the accelerator pedal and follows one

course shown in FIG. 3.

The one-shot timer circuit 22 generates timing pulses whose pulse width varies in accordance with that in FIG the control voltage Vc generated in the manner described above changes. In this embodiment, as a timer element a resistor-capacitor coupled monostable multivibrator that uses a resistor 40, a capacitor 41, transistors 38 and 39 and resistors 42, 43 and 44. The reference numeral 46 denotes a trigger circuit, the resistors 47, and 48, a capacitor 49 and a

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Diode 50 on v / eist. In the stable state the monostable When the timer circuit 22 has the structure described above, the transistor 38 is in the conductive state and the transistor 39 in the off state. If a trigger signal reaches the trigger circuit 46, the timer circuit is 22 is converted to the unstable state for a constant period of time during which the transistor J. 38 current leads and dpr transistor 39 is kept blocked. During this period, a time pulse with positive polarity is generated at the collector of transistor 31. The control voltage Vc of control voltage generator 21 appears at node C, which is across collector resistor 42 is connected to the collector of transistor 38, which is in the

stable state of the timer circuit is locked; v / ground the forward voltage drop across the base-emitter junction of transistors 38 and 39 and the collector-emitter saturation voltage at one of these transistors when it is conducting " state (lower than 1 volt for each transistor) ignored, witfd the pulse width T of the time pulse approximated as follows:

V.
T = RCIn (I + v | -) ,

where R is the resistance (in ohms) of resistor 40 of the time element, C is the capacitance (in farads) of the capacitor of the time element, Vc is the control voltage (in volts) at point C. and VD is the voltage (in volts) at the end of the resistor

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40, which faces away from the base of transistor 39. If R and C in equation (1) are assumed to be constant, the Pulse width T of the timing pulse can be changed as the puncture of the control voltage Vc. If Vc <r < VD, equation (1) can be approximated by the following equation:

V.
= RC —S-, ^ sec ^ / (2)

VD

If equation (2) is satisfied, the pulse width T is proportional to the control voltage V _c as long as the other factors are constant. An example of this relationship is shown in FIG. The constant factors are appropriately preset so that T = T when Vc = Vc and T = T _fl when Vc = Vc ".

The current amplifier 23 amplifies the time pulse of the monostable timer circuit 22 in terms of current to a sufficient one Level for actuating the electromagnetic valve 1. It has an amplifying transistor 51 and resistors 52, 53 and 54. Resistor 54 connected to the collector of transistor 51 is in series with the solenoid coil 11 of the electromagnetic valve 1. The time during which the electromagnetic valve 1 is in operation or is open is substantially proportional to the pulse width of the timing pulses, and therefore that is let through valve 1 Fuel quantity essentially proportional to the pulse

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- Il -

broad.

The reference numeral 55 denotes a trigger signal generator, the breaker contacts 59 has through
a cam 58 is actuated in an on-off mode which rotates at a constant primary rotation ratio to the engine crankshaft. The trigger signal generator provides the trigger signal for triggering the monostable ä Seitgeberschaltung 22 His cam 58 is connected to the drive shaft 60 of the plunger 3
(Pig. 1) connected so that it generates a trigger pulse for every quarter turn of the drive shaft 6O.

If the electromagnetic valve 1 is open, is
Fuel into plunger pump 3 through an inlet port
drawn.

As shown in Fig. 1, the plunger pump 3 includes a face cam € 1 that rotates with the drive shaft 60. The face cam 61 has four cam sections 62. A compression spring 61b is provided for cam operation.
A pump controller 64, which is integrally connected to the end cam 61 via a driven shaft 61c, can simultaneously rotate and reciprocate through the cam action between the end cam 61 and rollers 63 supported by a stationary roller ring 62 thereby the

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Distribute fuel and use it in accordance with the opening time between a distributor drum 65 and a lower cylinder Pull 66 into the pump. Fig. 5 shows an opening arrangement in a fuel distribution chamber for a Four cylinder engine. In this arrangement the distributor drum 65 has an inlet port 70 and four outlet ports 71, 72, 73 and 74, while the pump plunger 64 has four inlet ports 75, 76, 77 and 70 and one outlet port 79 having. The inlet openings 75 to 78 and the outlet openings 79 in the pump plunger 64 are in communication with a central channel 80 which leads into the plunger chamber 81 of the lower cylinder 66 opens. The pump plunger 64 reciprocates with every quarter turn of the drive shaft 60 The cam portions 61a of the end cam 61 become in rolling contact rotate with the corresponding rollers 63, the

Front cam 61 in the direction of arrow a against the restoring force of the compression spring 61b until the rollers 63 roll on the head of the cam link 61a, and then in the opposite direction shown by the arrow b by the restoring force of the spring 61b back to that in FIG retracted initial position shown, whereby a reciprocating movement of the pump plunger 64 is caused. During this iSince a quarter turn over the end cam 61 and transmit the driven shaft 61c to the pump plunger 64. The plunger 64 completes four reciprocations during

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one turn within the distributor flow 65. On this Thus, the fuel supplied by the electromagnetic valve 1 is drawn into and out of the plunger chamber 81 the corresponding outlet opening in the distributor drum 65 by the reciprocating movement of the pump plunger 64 pushed out. Leaving the fuel leakage between the pump plunger 64 and the distributor drum 65 and the pump 'J pen plunger 64 and the lower cylinder 66 out of consideration, the amount of from one of the outlet ports 71 to 74 is the Distributor drum 65 has a drain cycle equal to the amount of fuel drained by the electromagnetic valve 1 was fed in a fuel feed cycle. The of each outlet port 71 to 74 of the Distributor drum 65 discharged fuel is via a dispensing valve, provided at each exhaust port and an associated high pressure fuel line to an injector which is provided on the corresponding engine cylinder * and from which the fuel is injected.

It is now assumed in the operation of the above-described fuel control system that the angle Θ representing the amount of engine accelerator operation (depression of the accelerator pedal) is equal to Q ₁ . Under this condition, if the engine speed N is greater than N ₁ , the sum of the engine speed voltage VS and the reference voltage VF is less than Vz, so that that of the control voltage generator

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generated control voltage Vc the maximum value Vc ,. owns. In this case, the pulse width T of the timing pulse generated by the one-shot timer circuit 22 has the maximum value T 1, and the amount of fuel supplied via the electromagnetic valve 1 in one fuel supply cycle is Q _fl (maximum). The fuel thus supplied is drawn into the plunger pump 3 via the inlet opening 7O and then pressed out and distributed by the pump plunger 64 and thus forms the quantity Q of the fuel which is to be injected for the corresponding engine cylinder. If the engine speed N is at an average value between N, and N, the sum (VS + VF) is greater than Vz, so that the control voltage Vc has an average value which depends on the difference between (VS + VF) and Vz. In this case, the amount Q ^{1 of} the force released by the electromagnetic valve 1

substance and therefore the amount Q of the fuel to be injected has a mean value between O and Q. If the engine speed N is not less than N. ', the control voltage Vc has the minimum value Vc. In this case Q is ¹ or Q = O (minimum). m π

If the aforementioned angle θ is zero (minimum) or Θ _Η (minimum), the relationship between the amount Q ^{1 of} the fuel allowed by the electromagnetic valve 1 in a fuel supply cycle or the amount Q of the fuel to be injected in this period is for Engine speed N whole

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same; the diagram for θ = O or θ = θ., is the same like the diagram for θ = Θ, with the exception that the coordinate is shifted by N along the abscissa, as shown in FIG. The fuel injection characteristic 6 is completely analogous to the basic diesel engine fuel control sequence according to FIG. 3.

The foregoing has only been one embodiment of the fuel control system according to the invention described; however, numerous modifications are possible, some of which are listed below:

1) In the embodiment described above, the control voltage generator 21 is only used the essentials for fuel control of a diesel engine

To perform functions. It can be replaced by a control voltage generator which in addition performs a correction of the i fuel injection characteristic after starting of the engine and at no-load, slow speed and high speed running motor operation. Furthermore, factors such as the engine temperature and the atmospheric pressure can be detected. This can get the motor needs more precisely corresponding _"v control characteristics. _t

2) The drive shaft 60 of the plunger pump 3 can thus be arranged to be used with both the AC motor speed detector generator 26 as well as with the cam 58

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cooperates, which in on-off operation the breaker contacts 59 of the trigger signal generator 55 actuated.

3) A rotary fuel supply pump can also be installed in the plunger pump 3, such as a vane pump, which is driven by the drive shaft 60, and the Pressure of some of the fuel dispensed by the fuel supply pump may be constant on the order of a few Atmospheres, for example, by means of a relief valve are made ge, which is at the fuel inlet 10 of the electromagnetic Valve 1 is applied.

4) Furthermore, part of the fuel supply pump dispensed fuel can be used to operate a hydraulic timer of the same type

is like that in the conventional distributor type fuel injection pump used to automatically control the fuel injection time of the plunger pump.

5) Furthermore, the fuel supply pump can be used to obtain a constant fuel pressure of about several atmospheres for application to the fuel inlet of the electromagnetic Valve 1 instead of through the drive shaft 60 of the plunger pump 3 by a separate drive source, such as a Electric motor.

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6) Less than a constant amount of fuel dispensed by the plunger pump in one dispensing cycle Amount regardless of the amount of fuel admitted through the electromagnetic valve In the plunger pump 3, a shut-off drum having the same structure as that in the conventional distributor type injection pump may be used be provided; shut-off grooves can also be formed in the lower cylinder G6 and others required components, such as a smoke-setting screw and an under plunger.

7) A known analog function generator can be used as the control voltage generator in the control circuit for the electromagnetic valve. It is thus possible to set the control voltage characteristic following the engine operating states, ie to preset the control voltage curve. Thus, a desired fuel control pattern can be obtained. *

8) Although the embodiment described above deals with a distributor type fuel injection pump, in which the controlled amount of the fuel let through the electromagnetic valve 1 of the plunger chamber 81 is supplied via the inlet ports provided in the distributor drum 65 and the pump plunger 64, it is possible, the controlled amount of the fuel let through the electromagnetic valve 1 directly to the P lunger chamber

81 by making such an order,

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■ - 18 -

that the outlet of the electromagnetic valve 1 communicates with an inlet port formed in the sub-cylinder ζS is formed, and is open to the plunger chamber 81, In this Arrangement, the electromagnetic valve 1 must be operated so that it is for a certain period during the Fuel Föidehübs of the pump plunger 64 is closed. With this arrangement, it is not necessary to open fuel inlet ports in the distributor drum 65 and the PuranemrLunger 64 to form.

The invention thus provides a fuel control system formed using a plunger pump that has a single plunger that distributes and pushes out of the fuel to a number of hot water cylinders both rotated and reciprocated, and in which an electromagnetic on-off valve (open-close valve) is operated in accordance with a timing pulse voltage. from a control circuit which is in the fuel line is provided leading to the inlet of the plunger pump.

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Claims (1)

Claim Fuel control system characterized by a plunger pump (3), which has a single pump plunger (64) which simultaneously performs rotary motion and reciprocating motion for distributing and forcing out the fuel drawn into the plunger pump (3), through a control circuit (2) for a electromagnetic valve (1) which has a control voltage generator (21) for generating a control voltage following the engine operating states and a monostable timer circuit (22) for generating time pulses, the pulse width of which is determined by the control voltage, and an electromagnetic valve (1), which is provided in the line leading to the inlet of the plunger pump (3), fuel line and the i in a Kraftstofförderzyklus the electromagnetic VEN is TILs (1) in which in accordance with the pulse width of the timing pulses for controlling the amount of the fuel to and operated Plunger pump (3) is left. 109839/1084