EP0742357B1 - Injection regulating device for injection nozzles and method of adjustment - Google Patents

Abstract

The setting device consists of an injection setting mechanism, a setting drive (20) and a control unit. The setting drive consists of a translational element (19), an electrical setting member (21) and a position sensor. The setting member has an electric motor (40) which pushes the translational element along a thread (44,45) on which it is self-locking. The position sensor (55) produces a pulse when a shoulder (53) connected to the translational element passes it. There is also a pulse sensor (58) producing counting pulses. The sensors and the motor are connected to the control unit. From the pulses produced, this produces the actual position of the mechanism, compares this with a required position, and from this, produces control signals for the motor.

Description

The invention relates to a spray adjustment device for injection pump nozzles, consisting of an injection-adjusting Mechanism, one acting on it Adjustment drive and a control unit for the adjustment drive, the adjustment drive from a translational Element, an electrical actuator and one Position sensor exists.

There are different ways to adjust the start of injection, for pump nozzles are known: rotatable eccentric Rocker arm shaft or sliding control rod for each one or for all pump nozzles. With all such Mechanisms find one of an electrical Actuator driven translational element use.

A generic adjustment device is from the AT-B 377 581 known. With this one finds an eccentric one Rocker arm use by an electric Actuator is operated via a transmission. At this also attacks a position sensor that is in the rotational position gives the corresponding rocker arm signal. First is the direct attack of a gear on the Rocker arm axis problematic because of it forces to be absorbed their position during the injection stroke can adjust. Because of the small adjustment angle can neither the setting nor the position signal be exact, the device is therefore made for that Precise required to minimize emissions Spray adjustment not suitable.

A particularly big problem is the adjustment the spray adjustment device when assembling the unit and when they are installed in the internal combustion engine. Also in the course of the service life, due to wear, readjustment sometimes required.

According to the state of the art are in the assembly of the internal combustion engine first camshaft and rocker arm axis with respect fixed reference surfaces on the cylinder head by means of Teach to position accurately and in a particular Stake out the angular position. Only then can the assigned one Nominal pre-stroke (this is the stroke at which the injection begins when this is neither early nor late is adjusted) of the pump nozzle. That requires further manipulation with calibers or the like, because the rocker arm axis corresponds to that of the nominal forward stroke Position. After setting the Adjusting screw between pump element and rocker arm must be the position sensor must also be calibrated. To it is brought into two defined positions and the Both measured values are saved in the control unit. This Manipulations are very time consuming and cause in series production and later replacement, high costs.

In addition, the accuracy of the sensors and the Accuracy of assignment is slowly lost due to wear. A later re-calibration or replacement of the Pump nozzle is only possible with a similar amount of work.

The invention is therefore based on the object Spray adjustment device to be designed so that it high accuracy easy to install and adjust is to be specified, as well as a procedure according to which this adjustment with the highest throughout their lifespan Accuracy can be achieved in the shortest possible time is.

For this purpose, the device according to the invention has the characteristic Features specified in the first claim on. The fact that the electric actuator is a motor is the translatory element via a gear moves, the adjustment is very precise. The one in the transmission occurring friction acts to adjust the Mechanism during the pressure peaks of the injection stroke opposite. Therefore and because of the special control can found enough with a normal electric motor it is no longer an expensive stepper motor necessary.

The pulse sensor responsive to the rotation of the motor delivers very much because of the gearbox for a small stroke many, and therefore precise, high-resolution counting pulses, thereby the very necessary to minimize emissions fine adjustment of the translatory link achievable is. Game in the gearbox and any other games on The way to the injection mechanism could be accuracy adversely affect the setting, which is why in the case of known constructions, one strives for the Position sensor at the end of the impact chain and thus the game chain, so to arrange on the adjustment mechanism itself. Due to the short distance on this one only gets inaccurate low resolution signals. By using a barrier sensor and thanks to the adjustment method according to the invention However, the games cannot affect the accuracy of the adjustment. Moreover the barrier sensor speaks when passing the shoulder precise, which gives it a very precise and thereby suitable pulse as a calibration pulse.

The control unit can use the counting pulses and the calibration pulse then clearly determine the actual position and from it and from the target position an actuating signal for the Generate electric motor that is unaffected by games and dead times is because the counts also come directly from come to him. Finally, that the control unit In addition to the counting pulses, the calibration pulse is always available is counted each time the Barrier sensor automatically re-calibrated, so that counting errors or faults in the electric motor are corrected.

This also results in a considerable simplification of assembly, because the assignment between nominal advance and the Adjustment mechanism no precise mounting of camshaft and rocker arm axle requires more, but itself automatically sets.

The barrier sensor is a further development of the invention a HALL sensor that fits into the housing of the adjustment drive is used (claim 2). By using it a HALL sensor is even minimal Passing speed of the shoulder an undiminishedly accurate and strong calibration pulse. Due to the dimensionally accurate Installation in the housing according to the nominal stroke are all tolerances influencing the spray adjustment on a single easy-to-machine component - the housing - summarized what the manufacture and Assembly further simplified and cheaper.

In a particularly simple and inexpensive embodiment the HALL sensor is a fork barrier and that Shoulder is formed by a sheet metal plate, which in the fork is immersed (claim 3).

In another embodiment of the invention, the Motor via a worm gear a spindle nut that with a threaded spindle of the translatory element interacts. The spindle nut also forms the Friction brake. So in the simplest way is a high reduction ratio achievable which is the choice of one high-speed and therefore very small electric motor allowed. The relatively larger game of a worm gear does not fall thanks to the calibration method according to the invention Weight. The one with a worm gear and one Self-locking of the threaded spindle is a special one strong effect of the friction that occurs, leading to Absorption of the peak load on the injection stroke is desirable can be.

The invention also relates to a method for adjustment a spray adjustment device according to one of the previous claims that a simple and accurate Setting the injection pump after it has been installed in a Internal combustion engine and also later permitted. It is that the translational element from the engine the actuator is driven until the Shoulder has reached the barrier sensor and the motor is switched off when crossing the barrier and then the count of the pulse counter in the control unit is set to zero in this position (claim 4). This automatically, quickly and simultaneously does two things reached: The control unit knows which count pulse corresponds to the nominal advance stroke and the injection adjustment mechanism is in the range corresponding to the nominal preliminary stroke Position.

In a particularly advantageous development of the method the barrier sensor for adjustment is only ever happens in a specified direction (claim 5). Thereby all games in the adjustment mechanism are switched off and the adjustment is invariably accurate, too if the games grow over their lifespan.

To automatically ensure that this happening independently from the current position always in the same Direction takes place from the status of the barrier sensor decided in which direction the translational Element to move first is around the barrier sensor to happen in the specified direction, being in the case the barrier sensor has already passed the shoulder first moved past it in the opposite direction and only then drive in the specified direction will (claim 6).

To drive automation even further, can be provided be that the control unit makes the adjustment automatically triggered when the quantity-determining link Position taken to adjust the quantity assignment has (claim 7). When a pump unit is renewed or is reinstalled after repair, the Assignment between a certain control rod position and the position of a quantity-determining member of Pump can be set, which is usually unplugged the control rod becomes. From this position the control unit recognizes that it is a readjustment and sets this also automatically adjusts the spray adjustment in progress.

Finally, the process can also show signs of wear and other adjustments throughout Life cycle can be compensated for by the control unit Readjustment automatically at defined intervals triggers (claim 8). These distances can be on most simply defined by the number of starts be with every or every hundredth.

Fig.1:

einen Querschnitt durch die Kopfregion eines Dieselmotors,

Fig.2:

vergrößert das Detail A der Fig.1 als erfindungsgemäßer Teil der Verstelleinrichtung in einer Stellung,

Fig.3:

Ansicht B zu Fig.2,

Fig.4:

wie Fig. 2, jedoch in einer anderen Stellung,

Fig.5:

Wie Fig.4, jedoch einer anderen Ausführungsform,

Fig.6:

Schnitt nach VI-VI in Fig.5,

Fig.7:

Schaltschema der erfindungsgemäßen Einrichtung,

Fig.8:

Ablaufdiagramm zum erfindungsgemäßen Verfahren.

The invention is described and explained below with the aid of figures. They represent:

Fig.1:

a cross section through the head region of a diesel engine,

Figure 2:

1 enlarges detail A of FIG. 1 as part of the adjusting device according to the invention in one position,

Figure 3:

View B to Fig. 2,

Figure 4:

like FIG. 2, but in a different position,

Figure 5:

As in FIG. 4, but with a different embodiment,

Figure 6:

Section according to VI-VI in Fig. 5,

Figure 7:

Circuit diagram of the device according to the invention,

Figure 8:

Flow chart for the method according to the invention.

Only the top part of a diesel engine is shown in Fig.1 of the cylinder head 1 can be seen on which a camshaft housing 2 screwed on and closed with a valve cover 3 is. Inside there is a cam shaft 4, in addition to the unmarked valves also drives a pump nozzle 5. There is also a rocker arm 6 provided by an adjusting screw 7 on the piston foot 8 of the pump nozzle 5 attacks. The pump nozzle also has via a quantity-determining link 9, here a control rod. The rocker arm 6 is on a rocker arm axis 10 stored, the geometric axis 11 to the bearing means 12 in the camshaft housing 2 is eccentric. On the Rocker arm axis 10 is a clamp 13 for each pump nozzle screwed by means of a bolt 14, the eccentric lever 15 via a first pin 16 on a push rod 17 acts, which again with a second pin 18 is connected to a translatory element 19. This is part of the adjustment drive 20.

Fig. 2 and 3 shows the adjustment drive in more detail. On the camshaft housing 2 is an approach 30 formed and with a Bore 38 provided in the translational element 19 is performed. At the neck 30 is a base plate 31 attached and opposite by means of a centering 32 positioned this. Resting on the base plate 31 a housing 33 in which the adjustment drive 20 is accommodated is. It has three holes 34 through which it screwed together with the base plate 31 on the neck 30 is. It is on one side with a motor flange 35 provided and on its the camshaft housing 2 opposite end with a cover flange 36 on the a lid 37 is attached (removed in Figure 3).

An electric motor 40 is screwed onto the motor flange 35, its controlled power supply is not shown. Its shaft protrudes into the housing 33 and carries there a worm 41 which is connected to a worm wheel 42 combs. This is by means of the bearings 43 in the base plate 31 and mounted in the housing 33, its hub is a spindle nut 44. Their internal thread acts with a threaded spindle 45 together, firmly with the translational Element 19 connected or part of it. The threaded spindle 45 is limited by a stop collar 46, the stroke of the spindle nut 44 in its end position limited. The threaded spindle 45 sits on the Camshaft end facing away in a threaded extension 47 continues, on which a sleeve 48 by means of a Mother 49 is tightened.

The sleeve 48 carries a sensor plate 51 on one Friction brake 50 acts to damage the plate 51 to prevent during assembly. For the same purpose a guide rod 52 can also be provided. The Sensor plate 51 is folded (Fig.2) at its end and forms a shoulder 53 with a position sensor 55 cooperates. In the present embodiment is a HALL sensor that is dimensionally accurate in the Housing 33 is attached and a very accurate response barrier forms what is indicated by the dashed line 56 is. A sensor line 57 leads from the sensor path. Furthermore, a pulse sensor 58 is provided, which via line 59 is connected. This pulse sensor 58 interacts with the shaft of the electric motor 40. The Motor 40 is a very simple controllable electric motor at high speed, which is why it is sufficient to Wave to apply a single brand for pulse generation. In this Fig.2 is the adjustment drive 20 in an extreme position, corresponding to the latest possible start of injection.

In Figure 4, the same actuator 20 is in its other Extreme position corresponding to the largest possible pre-injection shown. It can be observed that the Shoulder 53 of the sensor plate 51 in this position is very far from the barrier 56, whereas in 2 the shoulder 53 has passed the barrier 56 and the bent part of the sensor plate 51 die Barrier also interrupts.

The variant shown in Fig.5 and Fig.6 differs differs from the previous one in that instead of Screw and screw spindle, from the motor - with or without intermediate reduction gear - a pinion 80 is driven, which in a toothing 81 of engages translatory element 19, which of a brake shoe 82 serving as a friction brake its movement is dampened. Preferably, that of Disc springs 83 force exerted on the element 19 by means of a screw 84 adjustable. Means can also be used be provided when driving the electric motor cause the friction shoe to lift off.

7 shows a circuit diagram of the invention Injection adjusting. The adjustment drive 20 is as Drawn box that contains the electric motor 40. The Control unit is designated 65, it contains an adjustment control 66 and a target value determination 67. Der Adjustment control 66 is via line 57 from the position sensor 55 emitted position signal and over the line 59 counts generated by the pulse sensor fed. The setpoint calculator 67 determines from various Input signals 68, e.g. Speed, accelerator pedal position, Engine temperature, a setpoint for the start of injection. This is also the adjustment control unit via a line 69 66 fed. From this is via lines 70 the engine operated controlled.

The adjustment method is now described with reference to FIG. 8: When assembling the internal combustion engine finally the camshaft 4, the pump nozzle 5, the Rocker arm axis 10 with the rocker arms 6, the clamp 13 with the eccentric lever 15, the push rod 17 with the entire Adjustment drive 20 mounted, see Fig.1. At this Assembly does not need any special adjustment procedures or gauges are used because thanks to the invention Process these settings only after and done automatically. Then the quantity assignment, which is not part of the invention in known or arbitrary made otherwise. In any case, it must the control rod 9 (Fig.1) staked out, that is in one specific position relative to the camshaft housing 2 be fixed.

The motor assembly is symbolized in FIG. 8 by box 80, staking out the control rod through the box 81. Now the control unit is switched on (box 82), which is the turning of a motor in the vehicle Means that the control unit recognizes that with the control device not subject to the invention that the control rod works together for quantity control is unplugged and triggers the adjustment process.

When the control unit is switched on, the Sensors activated. Since the spray adjustment device yes somehow installed, must first be determined what position it is in. This will be done first queried whether the position sensor 55 is in the position "EARLY" is located, see diamond 83. This is the case when the shoulder 53 of the sheet 51 not in the Barrier immersed. If it plunges, the adjustment device is So on "LATE", the electric motor is in Direction set to "EARLY" (box 85) and meanwhile continuously asked whether the position "EARLY" has already been reached, diamond 86 and loop 87. As soon as shoulder 53 has left the barrier is the nominal advance stroke (This is the basic position in which the spray starts is neither "EARLY" nor "LATE", so the electric motor turned a few more turns (e.g. 10) and then shut down. If already found in diamond 83 was that the position "EARLY" is present you are already in the position you have now reached, which is indicated by arrow 84.

Now the electric motor is switched on in the "LATE" direction (Box 89) until shoulder 53 crosses the barrier reached again. To do this, the position sensor is repeated interviewed, diamond 90 loop 91. If now the position of the Nominal advance stroke (in the always constant direction) reached is, the electric motor is stopped and the Pulse counter in the control unit, which receives the signals from the pulse sensor 58 counts, set to zero (box 92). Now is the position of the adjusting device is clear from the nominal advance stroke assigned (dashed box 93). Then it will be by means of the adjusting screw 7 and possibly one Teach the piston foot 8 to the adjusting screw 7 and the adjustment is finished.

For the re-calibration during the operating life is similar procedure, but only boxes 82 to 92 go through.

Claims (8)

1. An injection adjusting device for injection pump nozzles comprising an injection-adjusting mechanism (10, 13, 17), an adjusting drive (20) acting thereon and a control unit (65) for the adjusting drive, wherein the adjusting drive comprises a translatory element (19), an electrical setting member (21) and a position sensor, wherein

   a) the electrical setting member (21) has an electric motor (40) which displaces the translatory element (19) by way of a transmission (41, 42, 44, 45; 80, 81),

   b) the position sensor (55) produces a pulse when the translatory element (19) passes,

   c) there is further provided a pulse sensor (58) which is responsive to rotation of the motor and which delivers counting pulses,

   d) the position sensor (55), the pulse sensor (58) and the electric motor (40) are connected to the control unit (65) which produces setting signals for the electric motor (40) from the actual position of the injection-adjusting mechanism (10, 13, 17) and from a reference position,
   and wherein moreover

   e) the position sensor (55) is a barrier sensor which delivers a calibration pulse when a shoulder (53) connected to the translatory element (19) passes,

   f) the control unit (65) is connected to the barrier sensor (55) and to the pulse sensor (58) and from the calibration pulses and the counting pulses ascertains the actual position of the injection-adjusting mechanism (10, 13, 17), and

   g) the electric motor (40) co-operates by way of a pinion (81) with the translatory element (19), for which there is provided a friction brake (82).
2. An injection adjusting device according to claim 1 characterised in that the barrier sensor (55) is a Hall sensor and is fitted in accurately measured relationship into the housing (33) of the adjusting drive.
3. An injection adjusting device according to claim 2 characterised in that the barrier sensor (55) is a fork barrier and the shoulder (53) is formed by a small sheet metal plate which engages into the barrier sensor (55).
4. A method of adjusting an injection adjusting device according to one of the preceding claims after installation of the pump nozzles (5) in an internal combustion engine characterised in that the translatory element (19) is displaced driven by the electric motor (40) of the adjusting drive (20) and stopped when the shoulder (53) passes through the barrier sensor (55) and the counter condition of the pulse counter in the control unit (65) is set equal to zero in that position.
5. A method according to claim 4 characterised in that the shoulder (55) only ever passes the barrier sensor (55) for adjustment purposes in an established direction.
6. A method according to claim 4 characterised in that for that purpose the status of the barrier sensor (55) is used to decide in what direction the translatory element (19) is firstly to be moved to pass the barrier sensor in the established direction, wherein in the situation where the barrier sensor has already been passed the shoulder is moved therepast in the opposite direction and is only then moved in the established direction.
7. A method according to one of claims 4 to 6 characterised in that adjustment is automatically triggered by the control device when the quantity-determining member (9) is blocked in the position assumed for setting the quantity association.
8. A method according to one of claims 4 to 6 characterised in that the control device (65) also automatically triggers a post-adjustment at defined intervals after the first adjustment upon assembly.

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