DE10312712A1 - Control device and computer program for controlling a fuel valve of an internal combustion engine - Google Patents

Abstract

The invention relates to a control device and a computer program for controlling at least one fuel valve (300) with a piezo drive (100) of an internal combustion engine with direct petrol injection via a coupling element (200). The transmission behavior of the hydraulic coupling element (200) depends on various influencing factors, in particular on the period of the activation, on the activation period of the fuel valve (300) or on its load force. In order to compensate for an inaccuracy resulting from these negative influencing factors in the control of the fuel valve (300) by the piezo drive (100), it is proposed according to the invention that a stationary stroke loss characteristic of the coupling element (200) as a fault variable when the fuel valve (300) is controlled consider.

Description

The invention relates to a control device and a Computer program for controlling at least one fuel valve with piezo drive of an internal combustion engine with direct petrol injection Coupling element.

State of technology

It is from the state of the art known that in fuel valves with a piezo actuator the needle stroke on Valve seat due to charge applied to the piezo element as an actuator or voltage can be set. In the state of the art the fuel valve is usually not controlled by a direct connection to the actuator, but through a between the actuator and the fuel valve-connected hydraulic coupling element. This serves to measure temperature expansions and strains due to compressive forces as well Wear too compensate.

The disadvantage is the behavior this hydraulic coupling element depending on the Period of the control, that is, in particular of the speed the internal combustion engine, on the actuation duration of the fuel valve (Injection duration), from the load force of the fuel valve, which depends on the pressure in a fuel accumulator and on the damping constant of the hydraulic coupling element, which is not least of the Temperature of the hydraulic medium used depends.

Depending on the above negative influences turns up during the operation of the hydraulic coupling element a so-called "stationary stroke loss", which, if it is disregarded, leads to incorrect control of the fuel valve. More accurate said it can lead to an incorrect setting of the needle stroke of the Fuel valve and therefore an incorrect setting of the injection quantity of the fuel valve.

Based on this state of the art it is the object of the invention to provide a known control device for actuation a fuel valve over to further develop a coupling element and a computer program for such a control device, that they're a more precise Enable control of the fuel valve.

This task is accomplished by the subject of claim 1 solved. Accordingly, the task for the well-known control unit solved in particular by that it is designed to have a stationary stroke loss as one for the coupling element characteristic error size in the Control of the fuel valve to compensate.

Advantages of invention

Advantageously, this Compensation ensured according to the invention, that the stationary stroke loss no negative effects on the accuracy of the control of the fuel valve. Possible from the stationary stroke loss resulting errors or inaccuracies according to the invention the control unit compensated in advance of activation.

According to one embodiment the invention it is advantageous to the effects of the steady stroke loss as error size on the Stroke of the fuel valve and / or on the injection quantity in the in the control unit stored formulas, characteristic curves or maps for control of the fuel valve. By calculating the coupling behavior the effects are in the control parameters of the fuel valve of the stationary Errors due to speed, injection time, system pressure or valve temperature minimized on the needle stroke and / or the injection quantity. The valve stroke and the injection quantity can so be set more precisely.

Further advantageous configurations of the control unit are the subject of the subclaims.

The above task continues through a computer program for a control unit solved. The Advantages of this computer program correspond to those mentioned above on the control unit advantages mentioned.

drawings

The invention is a total of three Attached drawings, in which

1 a hydraulic coupling element;

2 the temporal relationship between the aforementioned injections and the size of the gap of the coupling element; and

3 shows a control device according to the invention.

description of the embodiments

1 shows the arrangement underlying the invention of a control device 50, a piezo drive 100 to control a fuel valve 300 in accordance with injection commands issued by the control unit 50 , In 1 can be seen that the piezo drive 100 not directly on the fuel valve 300 acts, but that between these two components, a hydraulic coupling element 200 is switched. This hydraulic coupling element is used to compensate for temperature expansions and expansions as a result of compressive forces and to compensate for wear.

2 shows a detailed view of such a coupling element 200 , It can be seen that the coupling element is essentially formed by a piston-cylinder arrangement, the piston being the reference symbol 220 and a cylinder for guiding the piston 210 Has. The piston 220 comes in with a hydraulic fluid 220 filled cylinder 210 guided. From the piezo drive 100 forces output to adjust the fuel valve 300 are according to 2 first on the piston 220 and from this via the hydraulic fluid 230 on the guide cylinder 210 before being transferred from there to the fuel valve 300 to get redirected. To realize a bidirectional power transmission between piezo drives 100 and fuel valve 300 is the coupling element 200 preferably evacuated inside.

As already mentioned in the introduction, the behavior of the hydraulic coupling element is 200 dependent on numerous above-mentioned influencing factors, which lead to the fact that during the operation of the coupling element 200 a so-called stationary stroke loss sets. This stationary stroke loss is in 2 denoted by the reference _symbol h _V.stat . It represents the path error caused by the interposition of the coupling element when the fuel valve is activated 300 through the piezo drive 100 can arise due to the influences mentioned.

In 3 is the general behavior of the coupling element 200 during its operation and the stationary stroke loss are graphically displayed as errors. In 3 the black rectangles shown on the lower timeline represent the controls of the piezo drive 100 through the control unit 50 and consequently also the injections E. The gaps between the injections represent the respective control pauses or the fillings B. From the graphic in 3 it can be seen that the coupling gap KS, plotted on the ordinate, in each case during the actuation times due to the piezo drive 100 applied pressure on the piston 220 drops significantly in order to then rise again with an e-function in the subsequent control pauses. These respective increases therefore result in no pressure from the piezo drive on the piston during the control pauses 220 and thus on the hydraulic fluid 230 is exercised. In 3 it can also be seen that the stationary stroke loss h _V.stat already mentioned occurs after a certain operating time.

wobei
r_k die Dämpfungskonstante des Kopplungselementes [N/(m/s)];
t_i die Ansteuerzeit;
F_S die Schaltkraft;
c_v die Steifigkeit des Ventils;
t_B die Dauer der Ansteuerpause (Befüllphase); und
h_v.stat den stationären Hubverlust repräsentiert.The stationary stroke loss h _V.stat can be calculated mathematically as follows:

in which
r _k the damping constant of the coupling element [N / (m / s)];
t _i the activation time;
F _S the switching force;
c _v the rigidity of the valve;
t _B the duration of the control pause (filling phase); and
h _{v.stat represents} the stationary stroke loss.

This steady stroke loss is shown by the fact that with continued operation of the coupling element the coupling gap KS is no longer able to regenerate itself completely during the control pauses B of the internal combustion engine, that is to say to grow back to its original value h ₀ . This original position h ₀ represents a distance between the pistons 220 from the bottom surface of the cylinder 210 , please refer 2 , The piston returns due to the steady stroke loss 220 as I said, no longer at its original distance h ₀ from the bottom of the cylinder 210 Rather, it only manages to _{move itself} from the bottom of the cylinder during the control _pause B by a distance of h ₀ - h _V.stat 210 to remove NEN; when he has reached this position, the drive pause for the internal combustion engine has already ended. The piston 220 is then activated again by the piezo element 100 caused to reverse its direction of movement and get back to the bottom of the cylinder 210 to approach, which results in a rapid shortening of the coupling gap KS.

Will this stationary stroke loss of the coupling element 200 when controlling the fuel valve 300 not taken into account, this leads to control errors; more precisely to an imprecise control.

To such, from the stationary stroke loss of the coupling element 200 resulting errors in the control of the fuel valve 300 To avoid, it is proposed according to the invention to compensate for this steady stroke loss during activation. More specifically, this stationary stroke loss can be taken into account when adjusting the stroke of the fuel valve and / or when adjusting its injection time. Advantageously, the known stationary stroke loss h _{V.stat of} the coupling _element used 200 already in the in a storage element 52 of the control unit stored formulas, characteristic curves or characteristic curve fields for controlling the fuel valve 300 considered.

The control of the piezo drive 100 and the fuel valve 300 is preferably carried out in accordance with a in the control unit 50 deposited computer program. This computer program regularly evaluates those in the storage element 52 stored formulas and characteristic curves for controlling the fuel valve. According to the invention, the computer program is designed such that it takes into account the steady stroke loss when the fuel valve is actuated.

The computer program can optionally together with other computer programs for controlling and / or regulating the internal combustion engine 50 be stored on a computer-readable data carrier. The data carrier can be a floppy disk, a compact disc, a flash memory or the like. The program code stored on the data carrier can then be sold to a customer as a product.

It is also possible that the computer program, possibly together with other computer programs without the aid of an electronic storage medium via a electronic communication network, in particular the Internet transferred to a customer as a product and is sold.

Claims (6)

Control unit for controlling at least one fuel valve ( 300 ) with piezo drive ( 100 ) an internal combustion engine ( 50 ) with gasoline direct injection via a coupling element ( 200 ), characterized in that the control unit ( 50 ) is designed to have a stationary stroke loss as one for the coupling element ( 200 ) characteristic error size when controlling the fuel valve ( 300 ) to compensate. Control unit according to Claim 1, characterized in that the control unit is designed to measure the stationary stroke loss when the stroke of the fuel valve is actuated and / or during the injection time for the fuel valve ( 300 ) to be included. Control unit according to claim 1 or 2, characterized in that the effects of the stationary stroke loss on the stroke of the fuel valve and / or on the amount of fuel to be injected into the internal combustion engine are taken into account in formulas, characteristic curves or characteristic curve fields, as used for the purpose of controlling the fuel valve ( 300 ) in a storage element ( 52 ) of the control unit ( 50 ) are saved. Control device according to one of the preceding claims, characterized in that the control device ( 50 ) is designed, the stationary stroke loss H _{Vstat of} the coupling _element ( 300 ) to be calculated as follows:

where r _{k is} the damping constant of the coupling element [N / (m / s)]; t _i the activation time; F _S the switching force; c _v the rigidity of the overall valve; t _B the duration of the control pause (filling phase); and h _{v.stat represents} the stationary stroke loss. Computer program for a control device ( 50 ) to control at least one fuel valve ( 300 ) an internal combustion engine via a coupling element ( 200 ), characterized by a program code which is designed for a stationary stroke loss of the coupling element ( 200 ) when controlling the fuel valve ( 300 ) to compensate. Computer program according to claim 5, characterized in that its program code is stored on a mobile data carrier is.