EP1555433A2 - Dosing pump system and method of operating a dosing pump - Google Patents

Abstract

The dosing pump system has a dosing pump (10) with at least one element (46) movable between two end positions and an associated drive (26,32) with a coil arrangement (26) and a drive arrangement for controlling the coil arrangement during a drive interval corresponding to a dosing pump element movement process in a pulsed manner, at least in respect of phase. An independent claim is also included for a method of operating a dosing pump system.

Description

The present invention relates to a metering pump system, in particular for dosed fuel supply to a vehicle heater, comprising a Metering pump with at least one between two movement end positions movable Dosierpumpenelement and one at least a metering pump element drive associated with a metering pump element, wherein the Dosierpumpenelementenantrieb a coil assembly and a Drive device comprising which for moving the at least one Dosierpumpenelements in at least one direction of movement, the coil assembly to generate a magnetic force interaction.

When used in motor vehicles as auxiliary heaters or Zuheizem Heaters are designed for efficient operation with the lowest possible Pollutant emissions required, which is a heating burner of such heaters To dose exactly to be supplied amount of liquid fuel. When used to Metering pumps is generally a pump piston in a cylinder slidably received. By moving the pump piston back and forth between two movement end positions, the volume a pump chamber are made maximum or minimum. In this manner and, when moving, to maximize the pump chamber volume the fluid to be pumped, so the liquid fuel recorded or sucked. When moving in the direction of minimizing the pump chamber volume This liquid fuel is then out of the pump chamber expelled while consuming towards the fuel consuming System, so the heating burner, promoted. The movement of the pump piston between his two movement end positions can thereby be attained that the pump piston towards one of his End positions is biased, for example, by a biasing spring. To counteract this pump piston then from this movement end position the spring bias out towards the other end position to move is a generally electromagnetically acting pump piston drive available. This can be a surrounding the pump piston Coil, which under the control of a drive device stands. By applying a voltage to this coil, i. excite same, then becomes by magnetic interaction with an anchor the pump piston displaced, contrary to the above already addressed bias. In this movement, but possibly also in the under spring tension then taking place backward movement on exit the excitement of the coil, there is a risk that when reaching a respective Movement end position of the pump piston to generate Noises and stop vibrations at a respective movement stop abuts. This is particularly critical because in such Metering pumps by the magnetic interaction a movement the pump piston is generated at the speed of which is progressive increases. The on reaching a movement end position then generated noises or vibrations are transmitted via the dosing pump on a supporting this support structure arrangement and may optionally in Vehicle interior are perceived. Besides the fact that this can be uncomfortable for vehicle occupants, persists the Danger that the repeated striking of the pump piston a Damage in different system areas of the metering pump, in particular also in the area of the pump piston, can occur.

A problem with the control of dosing pumps or the coil arrangement the same is further that the reaction obtained by this activation, So the displacement of the metering pump element, greatly varies in Dependence on the height of the applied to a coil assembly Tension. Is the voltage present in the vehicle electrical system comparatively high, Thus, a voltage applied over a predetermined period of time causes a voltage other displacement than in a case in which the on-board voltage is low. It should be further considered that the frequency or the Duration of the drive intervals must be varied to the flow rate adjust. Changed now in this variation, even to the Coil arrangement applied voltage, so creates a comparatively high inaccuracy in the adjustment of the flow rate.

From DE 101 03 224 C1 is a metering pump for a vehicle heater known, in which a pump piston in a pump chamber and a providing cylinder is movable back and forth and in the direction Minimization of the pump chamber volume biased by a spring is. The pump piston is not its own example, electromagnetic assigned to effective drive. It is also a valve assembly present, one positioned in extension of the pump piston Valve slide has. This valve spool is in one of his movement end positions biased by a biasing spring. From this Endstellung, the valve spool by excitation of a drive for the spool providing coil to be moved out to reach the other movement end position. In his movement end positions The valve spool once connects an inlet area for under Form fluid standing with the pump chamber, while in the other Movement end position the pump chamber with an outlet connected is. When positioning the valve spool in the former Movement end position is by the in the inlet area under form existing fluid of the pump piston against its spring preload shifted, so that the pump chamber volume increases and the Pump chamber is filled with the fluid to be delivered. By switching the valve spool in the second-mentioned valve position is now with Fluid filled pump chamber with the lower pressure Connected outlet, so that the spring preload following the Pump piston now in the direction of minimizing the pump chamber volume can shift and thereby the contained therein Liquid ejects to the outlet area. Again, there is at by magnetic interaction induced displacement of the valve spool the danger that when reaching a movement end position impact noises and vibrations that feel uncomfortable or to impair functionality can lead to such a metering pump.

It is the object of the present invention to provide a metering pump system and to provide a method for operating a metering pump, with which during the movement of a Dosierpumpenelements the formation of noise or vibrations when reaching a movement end position can be avoided.

According to a first aspect of the present invention, this object is achieved solved by a metering pumping system, in particular for metered fuel supply to a vehicle heater comprising a metering pump at least one dosing pump element movable between two movement end positions and one of the at least one metering pump element associated Dosierpumpenelementenantrieb, wherein the Dosierpumpenelementenantrieb a coil assembly and a drive device comprising, which for moving the at least one metering pump element in at least one direction of movement, the coil arrangement to generate a magnetic force interaction, wherein the Drive device is adapted to the coil assembly during a metering pump element moving operation corresponding Ansteuerintervalls at least phased pulsed approach.

The pulsed driving of the coil assembly becomes a moving state of the metering pump element driven thereby, in which a less abrupt deceleration when reaching a final movement position is obtained.

In the metering pump according to the invention may preferably be provided that the control of the coil assembly by the drive device for generating the magnetic force interaction the Apply one at least in phases during a drive interval pulsed voltage to the coil assembly causes.

To the required movement of the metering pump element in the various Obtain movement directions with the simplest possible structure To be able to, it is suggested that a duty cycle of the pulsed drive during a Ansteuerintervalls at least in phases decreases.

According to another particularly advantageous aspect of the present invention can be provided that a frequency of Dosierpumpenelementenbewegung is in the range of 1 to 20 Hz and that the frequency the pulsed drive is in the range of 200 to 2000 Hz. By the Decreasing the duty cycle toward the end of a movement process, that is, reducing the period in which the voltage is applied is relative to the period in which no voltage is applied is achieved that the speed of the metering pump element at Approach to a movement end position decreases. This contributes considerably further contributing to the generation of impact noise and vibration suppress.

The metering pump element can, for example, a for conveying However, fluid may include displaceable pump pistons a valve spool through which at least one fluid flow path can be locked or released. Of course it is It is also possible to use the principles of the present invention for metering pump elements to use, whose motion mode no Linear displacement, but a rotational movement.

According to another aspect of the present invention, the beginning said object solved by a method for operating a Dosing pump, in particular for supplying fuel to a vehicle heater, which metering pump at least one by exciting a Coil arrangement for generating a magnetic force interaction during a drive interval movable Dosierpumpenelement includes, at which method the coil arrangement during the Ansteuerintervalls is pulsed at least in phases.

In this method can be further provided that a duty cycle the pulsed excitation of the coil assembly during a Ansteuerintervalls at least in phases decreases.

Fig. 1

eine Längsschnittansicht einer Dosierpumpe, bei welcher die vorliegende Erfindung verwirklicht werden kann;

Fig. 2

ein Zeit-Spannungsdiagramm, welches das grundlegende Prinzip der Ansteuerung einer Spulenanordnung der in Fig. 1 gezeigten Dosierpumpe veranschaulicht;

Fig. 3

vergrößert ein im Diagramm der Fig. 2 erkennbares Ansteuerintervall, während welchem die Spulenanordnung der Dosierpumpe der Fig. 1 zum Verschieben eines Dosierpumpenelements erregt wird;

Fig. 4

in zeitlicher Zuordnung zu dem Spannungsverlauf der Fig. 3 die effektiv angelegte Spannung;

Fig. 5

die Verschiebung eines Dosierpumpenelements während des in Fig. 3 gezeigten Ansteuerintervalls;

Fig. 6

eine alternative Ausgestaltungsart einer Dosierpumpe, bei welcher die vorliegende Erfindung verwirklicht werden kann;

Fig. 7

ein der Fig. 3 entsprechendes Diagramm einer anderen Art der gepulsten Ansteuerung.

The invention will be described in detail below with reference to the accompanying drawings with reference to preferred embodiments. It shows:

Fig. 1

a longitudinal sectional view of a metering pump, in which the present invention can be realized;

Fig. 2

a time-voltage diagram illustrating the basic principle of driving a coil assembly of the dosing pump shown in Figure 1.

Fig. 3

increases a recognizable in the diagram of Figure 2 drive interval, during which the coil assembly of the metering pump of Figure 1 is energized to move a Dosierpumpenelements;

Fig. 4

in time allocation to the voltage curve of Figure 3, the effective applied voltage.

Fig. 5

the displacement of a metering pump element during the drive interval shown in FIG. 3;

Fig. 6

an alternative embodiment of a metering pump, in which the present invention can be realized;

Fig. 7

one of the Fig. 3 corresponding diagram of another type of pulsed drive.

In Fig. 1 is a metering pump 10, as used for example in motor vehicles used to convey fuel to a heater, in longitudinal section shown. This metering pump 10 generally includes an inlet area 12, in which liquid fuel is received, as well as a Outlet area 14, in which the funded by the metering pump 10 Fuel is discharged. In the inlet region 12 is an inlet pipe 16 placed on a housing part 18. The through the inlet pipe 16 flowing fuel first passes through a pot sieve 20, before entering a Opening 22 may occur in the housing part 18.

The housing part 18 is further connected to an outer housing 24, which surrounds a coil 26 outside. The coil 26 is on a ring-like yoke 28th wound and via a contact plug connection 30 in conjunction with a Drive device 32.

With the outer housing 24 is at the opposite to the housing part 18 Page a here of several parts assembled outlet 34 is provided, in which a valve ball 36 and a valve spring 38 of an outlet check valve 40 are received. One in the Outlet 34 formed passage opening 42 is in communication with a pump chamber 44. The volume of this pump chamber 44 can by a back in the longitudinal direction of the metering pump 10 and movable Pump piston 46 can be varied. The pump piston 46 is connected with a bolt 48 carried thereon and a gasket 50 which can close the opening 22, by a biasing spring 52 in the Representation of FIG. 1 biased to the right, so that the seal 50 on the housing part 18 is seated and thereby closes the opening 22. By Applying a voltage to the coil 26 and thus energizing the same means the drive device 32, the pump piston 46 together with displaced the armature 48 against the biasing action of the biasing spring 52, to minimize the volume of the pump chamber 44 and thereby eject the fuel contained therein via the check valve 40.

When the energization stops, that is, no voltage is applied to the coil 26 applied, the pump piston 46 moves the biasing action of the spring 52 following again in the positioning shown in Fig. 1. Upon reaching the movement end position shown in Fig. 1, the seal 50 comes in Attachment to the housing part 18, so that by the elasticity of the seal 50th a damping function is fulfilled. In order to move in the other direction, Thus, upon reaching the starting from the recognizable in Fig. 1 Position shifted to the left lying movement end position, a To be able to provide damping function is one made of elastic material trained damping plate 54 is provided.

Although the above-described elements 50 and 54 fulfill a certain damping function when a respective final movement position is reached, there is the problem, in particular when the pump piston 46 is displaced from the movement end position shown in FIG Pump piston 46 noise and vibration that can be felt in the vehicle. This occurrence of noise or vibration is all the more unpleasant, as, as veranschlaulicht in Fig. 2, such a metering pump is operated in clocked for more or less continuous conveying of fuel. Thus, to move the pump piston 46 against the biasing action of the spring in a drive period I _a between two points in time t _a and t _a voltage U _S by the driving device 32 applied to the coil 26, so that by means of the coil then generated 52 26 Magnetic force the mentioned shift occurs. The duration of the drive period _{I, a} is dimensioned such that taking into account the level of the voltage U _{S is} the desired piston displacement is obtained. In general, the duration of this interval is I _a in the range of 25 - ms are 35, wherein the procedure can be so here is that the interval contains a certain safety period, for example, that even at relatively low ambient temperatures, the complete movement of the pump piston 46 during a such interval can be obtained. To push back the pump piston 46, the excitation is then suspended during an interval I _out . In particular, by specifying the length of this interval I _from, in principle, but also by specifying the length of the drive period I _a, the working frequency and thus the delivery rate of the metering pump 10 can be adjusted.

According to the principles of the present invention is now provided that, as is illustrated in Fig. 2 during such a drive period I _a, then a pulsed actuation of the coil 26. This will be described below with reference to Figs. 3-5.

In Fig. 3 is such a drive interval I _a between the switch-on time _t, and off time t _off is. This drive interval I _a of time the voltage U _S is applied to the coil 26, but not in a continuous but in a clocked manner. In this case, the voltage U _S can be obtained from the vehicle electrical system or removed, it preferably being possible for a voltage U _S to be applied to decouple fluctuations in the supply voltage with respect to the on-board voltage, but always to a constant level. Thus, there is a pulsed drive signal or a pulsed voltage with intervals AN-I _a 'and OFF intervals _of I'. The ratio of the time period or intervals I _A 'to I _from' the so-called duty cycle determines the voltage applied to the coil 26 voltage. This duty cycle also essentially determines the voltage applied to the coil 26 effective voltage. The greater the duty cycle, the closer the effective voltage approaches the voltage U _S. The lower the duty cycle, the further the effective applied voltage decreases in comparison to the voltage U _S.

It has been shown that solely by applying a pulsed voltage during such a drive interval I _, the occurrence of impact noises when reaching the movement end position can be largely suppressed.

According to a further in Fig. 3 recognizable aspect of the present invention, a movement end position can be ensured to a further reduction of noises and vibrations stop upon reaching that the above-mentioned duty factor _a decreases over the duration of a drive period of time I. This can be realized, for example, that, as shown in Fig. 3, the time duration of ON-intervals 'is kept substantially constant while the duration of the OFF intervals _of I' I _a increases. This has the result that the frequency of the ON intervals I _A 'decreases, which corresponds to a corresponding decrease in the duty ratio. The consequence of this reduction in the duty cycle is a decrease in the effective voltage U _e , as illustrated in FIG. 4. This decrease in the effective voltage applied to the coil 26 voltage U _e in turn leads to the example illustrated in FIG. 5 movement behavior of the pump piston 46 _a during a drive period I.

In FIG. 5, the actuating path or the actuating position of the pump piston 46 is illustrated on the vertical axis, with 0 referring to the state shown in FIG. 1, for example, while S _{max represents} the other final movement state, that is, starting from the representation of FIG 1 maximum left shifted state. The solid curve k ₁ in FIG. 5 represents the movement of the pump piston 46 when the coil 26 is driven with the signal shown in FIG. 3. It can be seen that the slope of this curve k ₁ decreases as it approaches the final movement position S _max , which means that the speed of the pump piston 46 decreases in a corresponding manner. Here, for example, by suitably changing the duty cycle, it can be provided that an almost asymptotic approach to the final movement state S _max is achieved, so that a very gentle reaching of this position occurs. In contrast, the curve represents k ₂ in Fig. 5 the movement mode, such as is obtained at _a unpulsed, so constant actuation or energization of the coil 26 during a drive period I in the prior art.

Here is a significant increase in the speed of the pump piston when approaching the movement end position S _max recognizable, which has the problems already mentioned result.

The duty cycle reduction discussed above with reference to FIGS. 3-5 may also be achieved by so-called pulse width modulation. In this case, as shown in Fig. 7, be provided that the sum of the immediately successive intervals I _a 'and I _out' is kept constant, which in principle also has a constant pulse frequency result, however, the ratio of these two intervals is varied in such a way that toward the end of a Ansteuerintervalls I _a the ON interval I _a 'decreases while the OFF interval I _out ' increases. Thus, at substantially constant drive frequency or pulse frequency in the range of about 400 hz, a decrease in the effective voltage during a drive interval I _a can also be achieved, which in turn leads to a decrease in the movement speed of the pump piston.

The pulsed actuation of the metering pump 10 according to the invention for displacing the pump piston 46, in addition to avoiding impact noises and stop vibrations, further has the significant advantage that the movement of the pump piston 26 can be reproduced with significantly higher precision. By specifying a defined adjustable and largely uninfluenced by fluctuations in voltage U _S and also prescribing the possibly over a Ansteuerintervall I _a changing duty cycle I _a '/ I _off ', the movement of the pump piston 46 can be specified with high precision, which is a corresponding Precise specification or adjustment of the flow rate entails.

FIG. 6 shows an alternative embodiment of a metering pump. Components which components described above in terms Structure or function correspond, are denoted by the same reference numerals with the addition of an appendix "a".

In the metering pump 10a shown in Fig. 6, the pump piston 46a in a cylinder member 60a movable, in which also the pump chamber 40a is provided. The pump piston 46a is under again Bias of the spring 52a, the pump piston 46a in the direction Minimizing the pump chamber volume 44a biased. It is otherwise However, the pump piston 46a no further controllable drive arrangement assigned.

In the axial extension of the pump piston 46 a is formed like a pin Valve element 62a provided. This is now with the armature 48a firmly connected and is under bias of a biasing spring 64a. The Preload spring 64a acts on the valve element 62a such that this is biased in a movement end position, in which a damping plate 66a rests on the inlet nozzle 16a. Upon energization of the coil 26a by appropriate control by means of the drive device 32a Due to the magnetic interaction, the valve element 62a will collapse with the armature 48a then in the positioning shown in Fig. 6 or movement end position against the bias of the spring 64a moves. In this position, an opening provided on the valve element 62a is oblique extending groove 68a positioned to communicate with the pump chamber 44a with an outlet channel 70a, while an inlet channel 72a is not connected to the pump chamber 44a. Will the arousal the spool 26a terminates, so that the valve member 62a of the in Fig. 6 illustrated position to the right in its other movement end position is shifted, so the groove 68 a connects the inlet channel 72a with the pump chamber 44a ago.

This metering pump 10a shown in Fig. 6 functions such that at in the movement end position not shown in Fig. 6 positioned valve element 62a and then existing connection of the pump chamber 44a with the inlet channel 72a and the inlet portion 12a under admission pressure supplied liquid fuel can flow into the pump chamber 44 a and the pump piston 46a against the biasing action of the spring 52a from the positioning shown in Fig. 6 to the left in the direction of maximization of the pump chamber volume can move. Will then the Coil 26a is energized, the valve element 62a shifts to those in Fig. 6th shown positioning, so that now the connection between the filled with liquid fuel pump chamber 44a and the inlet area 12a is interrupted, while this pump chamber 44a now with the lower pressure outlet area 14a over the Outlet passage 70a is connected. The pump piston 46a can then conditionally by the biasing action of the spring 52a in the pump chamber 44a contained liquid fuel via the outlet channel 70a to Promote outlet 14a.

From the foregoing description, it can be seen that the metering pump 10a shown in FIG. 6 also has a metering pump element that can be moved by energizing a coil 26a, namely the valve element 62a, which is thus moved back and forth between two movement end positions. In principle, there is also the danger here that, when a movement end position is reached, in particular upon reaching the end movement position shown in FIG. 6, striking noises and vibrations are generated. As described above with respect to the metering pump of FIG. 1, in the metering pump 10a shown in FIG. 6, the drive device 32a can be driven pulsed during the drive intervals which are provided for moving the valve element 62a into the movement end position shown in FIG to achieve the effects described above. Again, the duty cycle over the duration of a Ansteuerintervalls away can be varied or reduced, for example by increasing the frequency or by pulse width modulation to obtain the illustrated in Fig. 5 with reference to the curve k ₁ also in the valve element 62a movement mode.

Of course, it is in both Ausgetaltungsformen described above also possible, the duty cycle and thus the effective Voltage over the duration of a move for a Dosierpumpenelements to keep the scheduled drive interval constant.

Claims (9)

A metering pump system, in particular for the metered supply of fuel to a vehicle heater, comprising a metering pump (10; 10a) with at least one metering pump element (46; 62a) movable between two movement end positions and a metering pump element drive (26,32; 26a) associated with the at least one metering pump element (46; 62a) , 32a), wherein the metering pump element drive (26, 32; 26a, 32a) comprises a coil arrangement (26; 26a) and a drive device (32; 32a) which, for moving the at least one metering pump element (46; 62a) in at least one direction of movement coil arrangement (26; 26a) controls to generate a magnetic force interaction, wherein the driving device (32; 32a) is adapted to the coil arrangement (26; 26a) corresponding during a Dosierpumpenelementenbewegungsvorgang drive period to control (I _a) phased pulsed least. Dosing pumping system according to claim 1,
characterized in that the actuation of the coil arrangement (26; 26a) by the driving device (30; 32a) for producing the magnetic force interaction applying a _(a i) at least phased pulsed during a drive period voltage (U _S) to the coil arrangement (26; 26a ) causes. Dosing pumping system according to claim 1 or 2,
characterized in that the at least one metering pump element (46; 62a) is biased to perform a moving action in a first direction of travel, and the driving device (32; 32a) controls the coil assembly (26; 26a) to perform a moving operation of the at least one metering pump element (46; 62a) in a first direction of movement opposite to the second direction of movement drives against the bias voltage. Dosing pumping system according to one of claims 1 to 3,
characterized in that a duty cycle (I _on '/ I _off') of the pulsed actuation decreasing phases _(one I) at least during a drive period. Dosing pumping system according to one of claims 1 to 4,
characterized in that a frequency of the metering pump element movement is in the range of 1 to 20 Hz and that a frequency of the pulsed driving of the coil assembly (26; 26a) is in the range of 200 to 2,000 Hz. Dosing pumping system according to one of claims 1 to 5,
characterized in that the at least one metering pump element (46) comprises a pump piston (46) displaceable for conveying fluid. Dosing pumping system according to one of claims 1 to 6,
characterized in that the at least one metering pump element (62a) comprises a valve slide (62a) displaceable for shutting off / releasing at least one fluid flow path (70a, 72a). Method for operating a dosing pump, in particular for supplying fuel to a vehicle heating device, which dosing pump (10; 10a) at least one by energizing a coil arrangement (26; 26a) for generating a magnetic force interaction during a drive period (I _a) movable Dosierpumpenelement (46; 62a ), comprises in which method the coil arrangement (26; 26a) _a) is energized at least phased pulsed during the drive period (I. Method according to claim 8,
characterized in that a duty cycle (I _on '/ I _off') (26; 26a) the pulsed excitation of the coil assembly during a drive period (I _a) at least in phases decreases.

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