EP0366743B1 - Regulating device for injection pump for injection engines, in particular diesel engines - Google Patents

Abstract

The regulating device described comprises an element (51) which senses the rotational speed of the injection pump shaft (1) and controls the pump rack (6). The movement of said rack is limited mechanically (61, 62, 63, 64, 65, 67), in a known manner, in function of the position of the accelerator pedal (67). The degree of movement of the rack (6) is therefore proportional to the distance travelled by the accelerator pedal (67). The essence of the invention is a d.c. generator the rotor (2) of which is mounted on the shaft (1) of the injection pump. The stator (4) of the generator is torsionally mounted on the pump against the force of a spring (41) and is linked by a mechanical transmission (43, 45) to a forked stop (46) which prevents further movement. The element (51) which senses the rotational speed of the pump shaft (1) regulates the excitation voltage of the stator (4) by means of a control unit (5).

Description

The invention relates to a control device of a fuel injection pump of an injection engine, in particular a diesel engine, with an electrical speed sensor which detects the speed of the drive shaft of the injection pump, which has a pump toothed strip which adjusts the amount of fuel conveyed by it and has a stop ring arranged thereon cooperates with a stop that is controlled adjustable via a control unit to which the speed sensor is connected.

Regulators are required for the smooth idling, the limitation of the highest speed, the adjustment of the engine power to the current load, and the automatic adjustment of the excess starting of an engine provided with a metering device, in particular a diesel engine. The need for regulation is due to the parameters of the engine on the one hand and the injection pump on the other. Without a control device or control, the injection pump would deliver the charge quantity - regardless of the engine speed - that belongs to the position of the toothed rack set by the accelerator pedal, which either leads to damage due to excessive engine speed or to uneconomical, smoking engine operation, which is caused by the additional supply, which arises due to the decreasing speed due to increasing load.

According to their operating principle, the regulators can be divided into pneumatic regulators with centrifugal weight, vacuum regulators and hydraulic regulators.

The known controllers generally have two separate zones, namely the idle zone and the end controller zone. Between these zones, the amount of fuel fed into the engine by the known control devices unaffected.

All known regulators have in common that they ensure the starting charge when starting and keep the idle speed by regulating the amount of charge at a constant value. At the same time, they reduce the amount of charge when the maximum engine speed is reached, thereby preventing the engine from rotating at too high a speed, and finally cut off the fuel supply when the engine is braking.

The known regulating devices are generally connected to the injection pump toothed strip in such a way that the external change in the charging is possible without the regulation from the outside being prevented. For this purpose, a rotatable adjusting shaft is mounted in the controller housing. The actuating shaft is connected to the component which changes the external charge, generally adjustable on the accelerator pedal by means of a linkage. On this actuating shaft, which rotates due to external influences, a control arm is supported via an eccentric shaft, which is connected on the one hand to the pump toothed strip and on the other hand to the output of the control device. As a result of the possibility of twisting the control arm twice, the control device does its job independently of the accelerator pedal position.

The simplest control devices are the flyweight controllers. In such a control device, the deflection of the centrifugal weights rotating as a function of the engine speed is transferred to the linearly movable pump toothed strip via lever arms. In the case of a stationary engine, the toothed bar is held in the position corresponding to the full charge by a spring. After starting the engine, its engine speed increases until the centrifugal weights - overcoming the spring force - begin to regulate the charge. As a result, the amount of charging decreases as long as the state of equilibrium between that by the accelerator pedal set engine speed and the amount of charge does not come about. Although the centrifugal speed governors are fairly common, they require frequent maintenance and care due to the numerous components subject to wear. Failure of maintenance can lead to damage, for example, due to excessive engine speed. Another disadvantage of these regulating devices is that their readiness to regulate depends on the characteristic of the spring which places the toothed rack on a full charge.

The control of a diesel engine can also be carried out with the vacuum created in the intake manifold of the engine using a pneumatic controller. The pneumatic control enables the pressure of the inflowing air to gradually decrease with increasing flow speeds in the intake manifold of the engine, that is to say with increasing engine speeds, that is to say a negative pressure is created.

The construction of the pneumatic controller is extremely simple. In this case, the charging bar that sets the charge is generally connected to a membrane that closes the end face of a closed vessel attached to the injection pump. The closed vessel is connected to the intake manifold of the engine, which creates a pressure difference on the surface of the membrane that is dependent on the negative pressure occurring in the intake manifold. The pressure difference is gradually increased with increasing speeds. When the engine is stopped, a spring arranged in the closed vessel pushes the membrane outwards, which means that the toothed rack is always pressed in the direction of full charging. When the motor is operating, the position of the toothed rack is determined by the balance of the pressure difference acting on the membrane and the spring force. Accordingly, the preload of the spring determining the end control should be set so that when the maximum engine speed is reached, the force resulting from the pressure difference is in equilibrium with the tension of the spring. After reaching the highest speed, due to the effects of increasing speed Decrease in pressure, the membrane and the toothed rack connected to it are increasingly moved back towards the zero charge against the compressive force of the support spring, that is to say the end control takes place.

In the case of an injection pump equipped with a pneumatic regulator, the linkage of the accelerator pedal must not be connected to the toothed rack, so that regulation from the outside is not prevented by the accelerator pedal. For this reason, the accelerator pedal is connected to the throttle valve arranged in the inflow cross section of the intake manifold. When the throttle valve is opened and closed, the vacuum generated in the intake manifold can be changed independently of the rotational speed, that is to say any charge can be brought about by a corresponding change in the force acting on the membrane.

A pretty big advantage of the pneumatic regulator, that is, the vacuum regulator, is the simple construction and the low cost. However, its disadvantage is that the motor can rotate at an impermissibly high speed if the membrane is damaged, which leads to damage to the motor.

Recently, the extremely reliable hydraulic regulators have spread more and more. With these regulators, the regulation is carried out on the basis of the fluid pressure which changes as a function of the speed. The fluid pressure, which changes as a function of the speed, is generated by a rotary wheel or rotary vane pump.

The fuel of the engine is generally used as the regulator working medium. As the speed of the engine increases, the gear pump delivers an increasingly larger quantity of fuel from the working cylinder to a pressure-compensating control piston, which is supported on the outside by a spring that can be tensioned by the accelerator pedal and is provided with a through hole. The fuel that forms the working medium flows through the bore in the space behind the regulator piston, and from there into the work area in front of a working piston that belongs to another working cylinder and is mechanically connected to the toothed rack of the injection pump. The working piston is moved under the effect of the working medium pressure, causing it to move the toothed rack towards full charge. In view of the fact that the amount of the working medium supplied by the gear pump increases proportionally to the engine speed, the flow resistance in the bore also increases and consequently the working medium pressure at the regulator piston increases proportionally. The increasing pressure moves the control piston against the spring force determined by the position of the accelerator pedal. As a result of this movement, the control piston closes the channel leading to the working space in front of the working piston connected to the rack and opens the outflow opening of the same working chamber and the opening of the channel introducing the working medium into the working space behind the working piston. Now the working piston moves the toothed rack towards zero charging. In the meantime, the liquid pressure on both sides of the regulator piston comes into equilibrium and the pressure force of the spring supported on the accelerator pedal pushes the regulator piston back into its starting position. This regulation lasts until the pressure force of the spring, which excites the regulator piston, and the pressure of the working medium, which is dependent on the engine speed, come into equilibrium. The final control is also ensured by a valve which opens at a pressure value corresponding to a certain engine speed and discharges the working medium.

The hydraulic regulator is much more complicated than any other known regulator. In addition, the small-sized controller or servo piston requires very precise machining and adjustment. The manufacture and adjustment of the regulator valve, as well as the assembly and adjustment of the spring that biases the regulator piston, can only be carried out by special machines. These additional costs are offset by the fact that Scheme is very reliable.

The common disadvantage of these controllers is that they only perform a starter, idle or end control. It follows that if the engine speed decreases due to a load, more fuel can be fed into the engine by depressing the accelerator pedal, which then - apart from the fuel waste - leads to the formation of polluting exhaust gas smoke. Finally, these controllers have the common disadvantage that if the controller fails, the motor can rotate at too high a speed, which can damage the motor. In motors with controllers of this type, this must be prevented by a special measure.

These disadvantages are already avoided by the hydraulic control device described in HU-B-194 598. Here, regulation takes place over the full speed range of the engine and it is ensured that fuel is always injected into the engine at the respective optimum engine speed. In addition, it is prevented under all circumstances that the motor rotates at an excessively high speed which leads to damage. Depending on the requirement, it is possible to prevent a predetermined speed from being exceeded, by means of which the economy, traffic safety and the service life of the motor vehicle are reduced. HU-B-194 598 namely proposes a regulator that feeds the fuel into the fuel using a feed pump that delivers a constant amount of fuel irrespective of the engine speed, through a magnetic bleed valve that is arranged in the suction line and that is electrically controlled by a control device that detects the engine speed Working cylinder of the control device leads. Accordingly, the regulation is carried out by drawing off the fuel as required.

From DE-A-2804038 is a control device of an injection pump of an injection engine with one Injection quantity controlling, displaceable control rod known. In this embodiment, a stop is arranged on the control rod and the displacement of the control rod by means of a control lever is limited by an adjustable full-load stop which interacts with the stop of the control rod. The position of the full-load stop is determined by a control unit via a stroke-controlled electromagnet depending on various operating variables of the engine, such as the engine speed. When the electromagnet is de-energized, the full-load stop is moved into its basic position by a spring.

AT-A-290212 also describes a control device of an injection pump of a diesel engine. The injection pump has a displaceable actuator which controls the injection quantity and is actuated by an operating lever which is elastically coupled to the latter. The actuator has an extension which engages in the recess of a rotatably mounted cam which limits the displacement of the actuator in both directions. The cam disc is rotated as a function of speed by an electric motor, which in turn is operated with the differential voltage between a generator which outputs a voltage proportional to the speed of the motor shaft and a device which generates a voltage proportional to the position of the cam disc. In this embodiment, the actuator is limited in its speed depending on the speed of the cam track on the cam.

The object of the invention is to provide such a control device which controls the injection pump of an engine in its entire speed range due to different operating parameters of the engine or its environment such that an adequate optimal amount of fuel is introduced into the engine at each speed value and that the exceeding a predetermined speed value that leads to damage to the engine is prevented. The control device should also be cheap and simple require minimal maintenance.

This is achieved according to the invention in that the control device has a generator controlled by the control unit with a rotor attached to the drive shaft and a stator rotatably mounted on it, rotatable against the force of a spring element and mechanically connected to the stop.

According to the invention, it is advantageous if the control unit is connected to further signal transmitters, which detect the operating parameters of the engine and / or its surroundings, and the generator is also controlled on the basis of the signals from these signal transmitters.

Furthermore, it is advantageous if the stator or the rotor of the electrical generator according to the invention is short-circuited.

Finally, it is advantageous if the generator according to the invention is self-exciting and the control unit is switched into the self-exciting circuit.

The invention is essentially based on the knowledge that when the rotor of a direct current dynamo or generator is driven by the resulting electromagnetic force, the stator also moves in the direction corresponding to the direction of rotation of the rotor, if the possibility exists. The possibility of this movement is ensured according to the invention in that the stator is rotatably arranged on the drive shaft of the injection pump with the interposition of a bearing, as a result of which the stator can rotate under the action of the electromagnetic force. The size of the electromagnetic force is regulated by an electronic control device in such a way that it only supplies the generator for generating the electromagnetic force with such a high electrical voltage that ensures the rotation of the stator by a predetermined corresponding amount.

• Die Drehzahl- und Drehmomentregelung ist im gesamten Drehzahlbereich des Motors sichergestellt.
• Auch im Falle veränderter Motorbelastung kann jedwelche vorbestimmte Motordrehzahl stets aufrechterhalten werden.
• Im Betrieb von mehreren Diesel-Motoren auf denselben Abtrieb kann der Drehzahl- und Drehmomentzusammenklang zwischen den Motoren sichergestellt werden.
• Eine zuverlässige Drehzahlendregelung ist gewährleistet. - Auch im Falle von Beschädigungen der Regelvorrichtung wird verhindert, daß der Motor sich mit zu Schädigungen führender Drehzahl dreht.
• Das Überschreiten einer vorbestimmten Geschwindigkeit des Kraftfahrzeuges ist verhindert.
• Eine analoge Regelung ist verwirklicht, die Pulsationen der Drehzahl ausschließt.
• Die Regelung kann den jeweiligen Anforderungen entsprechend angepaßt und weiterentwickelt werden. Zum Beispiel kann mithilfe von unterschiedlichen Sensoren, z.B. einem Wärmeüberschuß-Sensor, einem Luftüberschuß-Sensor, einem den äußeren atmosphärischen Druck erfassender Sensor usw., die mit der Steuereinheit verbunden sind, die Kraftstoffeinspritzmenge sowohl in negativer als auch in positiver Richtung den Anforderungen entsprechend korrigiert werden.
• Die "Rauchwirkung" des Motors ist wesentlich vermindert. Diese kann mithilfe der bereits erwähnten weiteren Sensoren weiter vermindert werden, wodurch der Motor im Betrieb auch die in den strengsten Normen vorgeschriebenen Werte befriedigt.
• Ein aus dem Gesichtspunkt des Umweltschutzes günstiger Motorbetrieb ist gewährleistet und die Verschmutzung der Luft ist vermindert.
• Die Regelungsvorrichtung kann an jedwelcher bereits funktionierender Einspritzpumpe nachträglich anmontiert werden.
• Die Regelvorrichtung kann in Serienproduktion billig hergestellt werden.

The advantages of the control device according to the invention can be summarized as follows:

• The speed and torque control is ensured in the entire speed range of the engine.
• Even if the engine load changes, any predetermined engine speed can always be maintained.
• When several diesel engines are operated on the same output, the speed and torque correlation between the engines can be ensured.
• A reliable final speed control is guaranteed. - Even in the event of damage to the control device, the engine is prevented from rotating at a speed that leads to damage.
• Exceeding a predetermined speed of the motor vehicle is prevented.
• An analog control is implemented, which excludes pulsations of the speed.
• The regulation can be adapted to the respective requirements and further developed. For example, with the aid of different sensors, for example an excess heat sensor, an excess air sensor, a sensor that detects the external atmospheric pressure, etc., which are connected to the control unit, the fuel injection quantity can be corrected in both negative and positive directions according to the requirements will.
• The "smoke effect" of the engine is significantly reduced. This can be further reduced with the help of the other sensors already mentioned, which means that the engine satisfies the values specified in the most stringent standards.
• A motor operation that is favorable from the point of view of environmental protection is guaranteed and the pollution of the air is reduced.
• The control device can be retrofitted to any already functioning injection pump.
• The control device can be cheap in series production getting produced.

Finally, the control device according to the invention does not require any maintenance because it has no components that are exposed to wear.

The invention is explained in more detail below using an exemplary embodiment with the aid of the drawing. The drawing shows a schematic diagram of the control device according to the invention.

In the illustrated embodiment, a drive shaft 1 of an injection pump, not shown, is mechanically connected to the main shaft of the engine, also not shown. The drive shaft 1 of the injection pump forms a unit with the shaft of a short-circuited rotor 2 of the direct current generator. A stator of the direct current generator containing an armature core 3 and excitation windings 31 is rotatably mounted on the shaft of the rotor 2 in bearings 42 against the force of a spring 41, in the exemplary embodiment of a tension spring. The stator 4 of the generator is connected via an articulated linkage 43 connected to the stator 4 and a swivel arm 45 rotatably mounted about a bolt 44 to a freely rotatable fork stop 46, on the fork part of which a pump toothed strip 6 movable in the longitudinal direction is guided. A stop ring 47 is adjustably arranged on the pump toothed strip 6, between the fork stop 46 and the end of the toothed strip 6 facing away from the injection pump. The pump toothed strip 6 is connected with its named end in an articulated manner to one end of an eccentric arm 61 which is mounted on a shaft which has an eccentric part which engages in the eccentric arm. At the other end of the eccentric arm 61 a linkage 62 is also connected in an articulated manner, the free end of which is connected to a compression spring 63. A linkage 64 is connected in an articulated manner to an arm fixed to the shaft of the eccentric arm 61, the other end of the linkage being connected to an accelerator pedal which can be pivoted about a shaft 66 against a spring 65 67 is connected in an articulated manner. A control unit 5 is arranged in or in the stator 4. The control unit 5, together with the speed sensor 51 which detects the rotational speed, the signal transmitters which are not shown in the example and which, in other exemplary embodiments, detect the operating parameters of the engine (such as the temperature of the engine, the oil, the cooling water), furthermore the operating parameters of the surroundings of the engine ( for example, temperature sensors, air pressure) detecting signal transmitters and has the electrical signals of these signal transmitters processing and evaluating circuits, as well as reference circuits and control circuits. The control unit 5 is also connected to a voltage source. In the exemplary embodiment, the speed sensor 51 is realized with a magnetic signal transmitter arranged on the shaft 1 and a winding which detects the pulses generated due to the rotation of the shaft 1. The transmitter is connected to the processing and evaluating circuits of the control unit 5. The electrical signals from the sensors pass through the reference circuit, in the exemplary embodiment through the reference circuit monitoring the speed, into the control circuit. Finally, the control circuit regulates the strength of the current flowing in the excitation windings 31 and belonging to the respective speed.

When the engine is out of operation, the control device according to the invention is in a de-energized state. The stator 4 of the generator is in a rest position due to the action of the spring 41, in the exemplary embodiment of the tension spring. The fork stop 46 is pivoted via the linkage 43 by the swivel arm 45 against the stop 47 and holds the pump toothed strip 6 in zero charge, that is to say in the closed position, regardless of the extent to which the accelerator pedal 67 is depressed. If, in this position, the accelerator pedal 67 is pressed down against the force of the tension spring 65, the linkage 64 is moved by rotating the shaft 66 and the eccentric arm 61 can only rotate on the eccentric part because the pump toothed strip 6 with its stop 47 on the fork stop 46 is present. Accordingly, the Eccentric arm 61 together via the linkage 62 only the compression spring 63, without the pump toothed strip 6 being moved.

When the engine is started, the control unit 5 is energized by turning the ignition key. Then, when the engine is started, the main shaft of the engine, the drive shaft 1 of the injection pump connected to it and thereby also the rotor 2 are set in rotation. Now the excitation winding 31 receives such a high predetermined voltage from the control unit 5 that the electromagnetic force which arises between the rotor 2 and the armature core 3, or the excitation winding 31 surrounding it, forces the stator 4 to an angular rotation of a predetermined magnitude against the force of the spring 41 . The stator 4 pushes the linkage 43 in proportion to the angular rotation, as a result of which the swivel arm 45 is pivoted about the bolt 44 and the fork stop 46 is moved in the direction of the greatest charge. This enables the pump toothed strip 6 to be moved in the direction of maximum charging in proportion to the angular rotation of the stator 4 when the accelerator pedal is depressed.

After the engine is started, the accelerator pedal 67 is returned to the idle position. The control unit 5 regulates the idling speed of the engine to the predetermined constant value under all circumstances using the speed sensor 51. This is made possible by the voltage control circuits installed in the control unit 5 and monitoring the speed, the control pulses being supplied to these circuits by the speed sensor 51 which detects the speed in accordance with the respective engine speed.

With the aid of the control described, an optimal amount of supercharging can be set for each speed of the engine, which is required for the smoke-free, complete combustion of the injected fuel. This so-called "smoke limit" is - considering the characteristic ones Requirements for the different engines - determined empirically.

The control device according to the invention also ensures that the circuit detecting the speed in the region below the so-called "smoke limit", taking into account the respective load on the engine, can only inject such a quantity of fuel that is absolutely necessary to maintain the given speed.

In the case of a motor vehicle on a downward slope, the injection of the fuel is interrupted by the accelerator pedal 67 being raised, the electromagnetic control device also interrupts the injection of the fuel until the decreasing engine speed reaches the idling speed. At the idling speed, the injection starts again automatically, which prevents the engine from stalling.

When the engine brake is used, the fuel injection is interrupted in that, after the accelerator pedal 67 is raised, a toggle circuit of the circuit of the control unit 5 which detects the speed switches over to the function monitoring the idling speed, as a result of which the power supply to the excitation winding 31, that is to say the control of the generator, is interrupted becomes. Now the stator 4 of the generator is retracted into its basic position by the force of the spring 41 and thus also the linkage 43 and the swivel arm 45 are retracted, which is pivoted about the bolt 44 and strikes with the fork stop 4 against the stop 47, whereby the Pump rack 6 is pushed back towards zero charging.

If the engine speed exceeds the idling speed, the breakover circuit of the circuit detecting the speed of the control unit 5 switches over to the function monitoring the maximum speed. When the engine speed reaches the predetermined maximum value, it is determined by the Control unit 5 stabilized in the manner already described and a further increase in speed is not permitted under any circumstances.

Claims (4)

1. Regulating device for a fuel injection pump of an injection motor, in particular a diesel engine, comprising an electrical speed transducer (51) detecting the rotational speed of the drive shaft (1) of the injection pump, the injection pump comprising a pump rack (6) setting the amount of fuel supplied by the pump and having an abutment ring (47) arranged on the rack, the abutment ring (47) cooperating with an abutment member (46) displaceable under control of a control unit (5) to which the speed transducer (51) is connected, characterised by a generator controlled by the control unit (5) and comprising a rotor (2) mounted to the drive shaft (1) and a stator (4) rotatably supported on the drive shaft (1), the stator (4) being rotatable against the force of a return spring (41) and mechanically linked to the abutment member (46).
2. Regulating device according to claim 1, characterised in that the control unit (5) is connected to other transducers detecting the operating parameters of the engine comprising the injection pump, and/or of its environment.
3. Regulating device according to claim 1 or 2, characterised in that the stator (4) or the rotor (2) of the electric generator is short-circuited.
4. Regulating device according to any of claims 1 to 3, characterised in that the generator is self-excited and the control unit (5) is inserted in the self-exciting circuit.

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