FR2797659A1 - METHOD FOR DETERMINING THE VALVE GAME - Google Patents

Abstract

A gas change valve (5a, 5b, 6a, 6b) of a cylinder of an internal combustion engine is actuated by an adjusting device (2, 3) independently of a camshaft and is controlled by a control device to which are sent a switching signal, which indicates the opening or closing of the gas change valve, and a crankshaft position signal.Depending on the method, the instants of the top dead centers of the cylinder are determined at from one of the two signals, the top dead centers of the cylinder at which a mixture ignites are determined from the other of the two signals and, in at least one of these top dead points of the cylinder to which a mixture s 'lights, the controller takes the valve clearance as the clearance between the adjuster and the gas change valve.

Description

The invention relates to a method for determining the valve clearance in

  a gas change valve, operated independently of a camshaft, an engine

internal combustion.

  Internal combustion engines are known, the gas change valves of which are actuated independently of a camshaft. Unlike gas change valves operated by camshaft, these gas change valves are controlled to open and close according to the angular position of the crankshaft; there is no rigid mechanical coupling with the crankshaft. For example, by DE 297 12 502 U1 or EP 0 724 067 A1, we

  knows electronic type adjustment devices

  mechanical for gas change valves. They have a rest position which is located between a closed position and an open position and of which it is

  possible to separate them by means of electromagnets.

  To open or close a change valve

  gas, a current is sent into the coil of the electro-

  associated magnet, the current required being greater in an initial phase than in a holding phase in which the valve is maintained in an end position. While, in the case of a conventional valve control actuated by camshaft, there is no prescription of control times in the operating control device of the internal combustion engine, it is appropriate, in the case of electromagnetically actuated gas change valves, that suitable control times are calculated

and prescribed.

  If a current is simply sent to the electro-

  With the corresponding magnet, the seat valve plug arrives at the valve seat at a high speed, which produces noise and causes wear. To avoid this, the power supply is subject to

appropriate regulation.

  In such "inlet" regulation, account should be taken of the valve clearance. This is why it is necessary to determine the valve clearance which is present between an adjusting device, and which actuates

  the gas change valve, and this valve.

  To this end, the subject of the invention is a method for determining the valve clearance of a gas change valve of a cylinder of an internal combustion engine which is actuated by an adjustment device independently of a shaft. and which is controlled by a control device to which a switching signal is sent, which indicates the opening or closing of the gas change valve, and a crankshaft position signal from which the position of the crankshaft can be deduced , characterized in that a) the instants of the top dead centers of the cylinder are determined from the crankshaft position signal or the switching signal, b) the top dead centers of the cylinder at which a mixture ignites are determined from the switching signal or crankshaft position signal and, c) in at least one of these top dead centers of the cylinder at which a mixture ignites, the control device takes the valve clearance comm e being the clearance between the adjustment device and the gas change valve. According to the invention, the valve clearance corresponding to that of the top dead centers of the cylinder

  at which a mixture ignites (TDC-ignition) is determined.

  At this time, independently of the actuation of the cylinder gas change valves, these valves are closed under the effect of the high pressure prevailing in the cylinder and remain so if not controlled

  otherwise the adjuster.

  So that the control device which controls the adjustment device actuating the gas change valve knows the top dead centers at which a mixture ignites, a switching signal, which indicates the opening or closing of the corresponding valve, and a crankshaft position signal are analyzed

in an appropriate way.

  The instants of the cylinder top dead center are then determined from the crankshaft position signal or the switching signal. Those of the top dead centers at which a mixture lights up are deduced from the other of these signals, so that the instants at which the valve clearance can be taken as being the clearance between the adjustment device and the

gas change valve.

  In this case it is important that one of the signals (switching signal or crankshaft position signal) indicates the top dead center exactly over time. The other signal should only

  allow recognition of TDC-ignition.

  To this end, advantageously, the adjustment device is released from an end position associated with the top dead center, so that the clearance between the adjustment device and the pressure valve

  gas change can be detected.

  More specifically, the method according to the invention may have the particularity that, at the top dead center, the adjustment device is in an end position and is released from this position

from end to step c).

  In addition, advantageously, a stroke signal, which indicates the stroke of the adjusting member, is produced. From the value of this stroke signal, it is possible to read the valve clearance during a

  release of the adjustment device.

  More specifically, the method according to the invention can also have the particular feature that a stroke signal indicating the stroke of the gas change valve is produced and the valve clearance is

  determined in step c) using the stroke signal.

  According to an advantageous development of the invention, the gas change valve is actuated by electromagnetic means and, for this purpose, there is provided at least one inlet regulator, which controls this gas change valve according to the signal switch, and a communication computer which, from the crankshaft position signal, produces the

  switching for several incoming regulators.

  The inlet regulator smoothly and silently arrives at the gas change valve in the end positions and determines the clearance for this purpose.

valve.

  According to another preferred development of this embodiment, the communication computer and the arriving regulator communicate by means of an SPI bus. SPI communication takes place at specific times. This SPI communication occurs, for a given gas change valve, only once per working cycle (720 of crankshaft angle for an internal combustion engine with 4 cylinders). From this SPI communication representing the switching signal, in common with the crankshaft position signal or a replacement signal produced by the communication computer, the arrival regulator can determine precisely over time and without equivocates the top dead centers to which a mixture

lights up.

  The method according to the invention may also have one or more of the following features: - the inlet regulator takes account of the determined value corresponding to the valve clearance, in order to ensure a smooth and noise-free arrival of the gas change in the end positions, - the crankshaft position signal is derived from a CAN bus signal, - the crankshaft position signal is derived from a SPI bus signal, - a binary signal one of which level change is associated with opening or closing the gas change valve is used as the switching signal, one signal level being associated with a closed gas change valve and the other signal level being associated with an open gas change valve, - the value corresponding to the valve clearance is updated adaptively, - in step a), the top dead centers are determined exactly in the t emps and, in step b), a recognition of those of the top dead centers to which a

mixing lights up.

  The invention is set out below in detail with reference to the drawings. In the drawings, we see: in Figure 1, a schematic representation of the circuit comprising gas change valves with electromechanical actuation for an internal combustion engine with 4 cylinders, in Figure 2, the variation over time of a signal indicating the top dead center and of a switching signal and, in FIG. 3, the variation over time of a crankshaft position signal, of the instants of a communication by SPI bus and of the possible instants of opening of the intake and exhaust valves of a cylinder of a combustion engine

internal 4-cylinder.

  The circuit of Figure 1 is used to control gas change valves 5a, 5b, 6a, 6b with electromechanical drive. Such an electromechanical drive gas change valve is for example described in the German utility model 297 12 502 U1. For the understanding of the present invention, it is only important that the gas change valve is actuated by means of the current supply of two coils, one coil being responsible for closing the valve and the other responsible for opening of it. To maintain the gas change valve in the open or closed position, a holding current is sent to the respective coil. To bring the valve into the open or closed position, a current is sent to the coil whenever necessary, the current in an initial phase being more

  greater than in the following maintenance phase.

  Figure 1 shows schematically the circuit corresponding to an internal combustion engine with 4 cylinders, but this number of cylinders should be taken as an example. In the present example, a cylinder has two intake valves 5a, 5b and two exhaust valves 6a, 6b. There are provided, respectively for the inlet valves 5a, 5b or the exhaust valves 6a, 6b, inlet regulators 2 and 3 respectively which are specific to them. The inlet regulator 2, 3 controls final stages which ensure the application of current to the respective coils of the valves 5a, 5b, 6a, 6b. For example, there is provided, for each coil, a final stage which

is clean.

  The arrival regulator 2, 3 controls the final stages of a gas change valve 5, 6 as a function of duration prescriptions supplied by a communication computer 1 which is yet to be described below. For example, a time control (or synchronization) signal VS can be sent to the inlet regulator 2, 3. For the inlet valves and the outlet valves of each cylinder respectively, there is a specific VS time control signal. In the case of an internal combustion engine comprising more than two gas change valves per cylinder, there may also be provided, for each valve, a signal VS

its own.

  The time control signal VS is for example a rectangular signal in which the falling edge indicates the opening of the associated gas change valve and the rising edge indicates the

  closing it; it is shown in Figure 2.

  The inlet regulator 2, 3 includes a digital processor which regulates the current supply to the coils by means of the final stages in such a way that the valve 5a, 5b, 6a, 6b arrives

  softness in the desired end position.

  Usually, to bring the gas change valve from one end position to the other, the current supply to the coil corresponding to the end position to be left is switched off and the current supply to the coil of the electromagnet corresponding to the new end position to be adopted is switched on. The current is regulated by the processor of the inlet regulator 2, 3 in such a way that the valve arrives smoothly in the new end position. For this regulation of each gas change valve, the arrival regulator 2, 3 uses a stroke signal which provides information on the position of the valve a, 5b, 6a, 6b each time considered. To produce the stroke signal, each electromagnetic drive of the valves 5a, 5b, 6a, 6b is provided with its own position sensor, this being as for example described in the German patent application 197 53 275 or in DE 195 18 056 A1. Alternatively, in place of the travel signal, it is also possible to use any other desired quantity as a guide and regulation quantity of the arrival regulator. The regulation of the coil current for the initial control phase of the gas change valve a, 5b, 6a, 6b is for example described in principle in DE 195 26 683 A1. For this purpose, the incoming regulator measures the actual current flowing in the coil

  and delivers the set value to the final stage.

  However, instead of the current, it is also possible to use another quantity which expresses the actuation of the adjustment device, for example the

  attack voltage of the final stage.

  The communication computer 1 is connected to a CAN bus 8 and ensures by means of this communication with an operating control device 9 of the internal combustion engine. Such a bus connection is for example described in W. Lawrenz, CAN-Controller Area Network, Higig Verlag, 1994, ISBN 3-7785-2263-7. The communication computer 1 also receives the crankshaft position signal and calculates therefrom, and in common with the conditions required by the operating control device 9, the time control signals VS corresponding to the regulators d 2, 3 and it delivers them to these arrival regulators 2, 3 by means of communication lines

unidirectional 4.

  In an alternative embodiment, each arrival regulator 2, 3 receives from the communication computer the duration prescriptions intended for the switching of the gas change valves not by means of a time control signal VS, but by means of a SPI series 7 bus. For this purpose, each arrival regulator 2, 3 also reviews a general CRK crankshaft position signal from which the regulator

  arrival 2, 3 can deduce the position of the crankshaft.

  Therefore, a time control signal for each arrival regulator 2, 3 is not necessary. By means of the SPI bus 7, it then suffices for the communication computer 1 to transmit to the inlet regulators 2, 3 the indication of the crankshaft position in which a gas change valve must be opened or closed. It is sufficient that communication via the SPI bus 7 takes place at a certain minimum interval of time before the valve switching operation to take place. This results in the advantage that the communication computer 1 and the incoming regulators 2, 3 can exchange state information

  or fault information via the SPI bus.

  In order for the inlet regulator 2, 3 to be able to bring the valve smoothly into the end position each time considered, it must be aware of the valve clearance existing between the

  regulator and gas change valve.

  This can take place in three ways: 1. If the duration prescription applied to the arrival regulator 2, 3 by the communication computer 1 takes place by means of a time control signal VS, the top dead center at which a mixture lights up (hereinafter called TDC- ignition) is determined as follows: the communication computer 1 reads the signal from a toothed wheel sensor which examines the passage of a wheel fixed to the crankshaft. From this signal, it produces the crankshaft position signal CRK which is represented by way of example in FIG. 2 and which indicates to the arrival regulator 2, 3, in a precise manner over time, the instants top dead centers of the cylinder for which it controls the gas change valves 5, 6. These moments are indicated in the signal CRK by the rising sides. Descending flanks indicate a low dead center. In the case of the 4-cylinder internal combustion engine shown here, there is a crankshaft angle of 180 between a top dead center and a bottom dead center. A full work cycle covers 720 crankshaft angles, which means that in a full work cycle there are two top dead centers, as shown by the rising edges of the CRK signal in Figure 2. In order to being able to unequivocally determine which of these rising sides is associated with a TDC-ignition, the arrival regulator 2, 3 analyzes in addition the time control signal VS. Since at TDC-ignition, all the gas change valves must be closed, among the two rising sides of the sign CRK which occur over a range of 720 of crankshaft angle, it cannot be a question of a TDC-ignition only for that for which the signal VS has a high level, which, in the example shown, corresponds to a closed gas change valve. Thus, the arrival regulator 2, 3 can unequivocally determine the instant Z-OT of the TDC-ignition. 2. If the duration prescription applied to the arrival regulator 2, 3 by the communication computer 1 takes place by means of a communication by SPI bus, the TDC-ignition is determined as follows: as in the case of the above embodiment, the arrival regulator 2, 3 receives the crankshaft position signal CRK. From this, the arrival regulator 2, 3 determines, here again, the instants of the top dead centers of the cylinder, of which it controls the gas change valves 5, 6. In order to be able to determine unequivocally which top dead center is present, the arrival regulator 2, 3 analyzes in

  supplement the instants of a communication by SPI bus.

  To this end, to allow the presentation, it is shown in Figure 3 a variation over time of the gear signal and the tooth of the wheel to be detected which is associated with it each time. The gear signal is taken to line 10 and the tooth associated to line 11. The top dead centers are precisely associated with a tooth passing from the crankshaft signal; in Figure 3, this is for example the

  tooth 20. If tooth 20 passes, it is either a TDC-

  ignition (Z-OT in Figure 3), or from a top dead center with load change (W-OT in Figure 3). Line 12 indicates which tooth is associated with a top dead center (Z-OT or W-OT) or a bottom dead center (UT). On line 13, the INVOPEN time window is entered in which the inlet valve can be opened. On line 14, the time window EXVCLOSE is carried in

  which the exhaust valve can be closed.

  At line 15, the time window INV_CLOSE is entered in which the inlet valve can be closed. Finally, on line 16, the time window EXV_OPEN is brought in which the exhaust valve can be opened. The representation of FIG. 3 thus covers a working cycle of the internal combustion engine, for which it is, in the present example, a 4-cylinder engine, only the time windows

  corresponding to a cylinder A being shown.

  It can be seen in FIG. 3 that the communication by SPI bus corresponding to the intake valve precedes, by a certain time interval, the possible time window INV CLOSE in which the intake valve can be closed. It takes place in the SPIINV time window located between the passage of teeth 45 and 53. Similarly, the instant of communication by SPI bus used to control the exhaust valve precedes, by a certain value, the EXV OPEN time window in

  which the exhaust valve can be opened.

  This communication by SPI bus takes place in the time window SPI_EXV located between the passage of tooth 59 and

that of tooth 7.

  From the moment of communication by SPI bus, for example corresponding to the intake valve, the arrival regulator 2, 3 can unequivocally determine which of the rising edges of the signal of

  CRK crankshaft position is associated with TDC-

  ignition. It appears for example from FIG. 3 that the second top dead center which follows a communication by bus

  SPI regarding the intake valve is a TDC-

  ignition. Thus, the arrival regulator 2, 3 can

  unequivocally determine the Z-OT instant of the TDC-ignition.

  3. As a variant, the gear wheel signal can be sent directly to each arrival regulator 2, 3. From this signal, the top dead centers can then be determined in an exact manner over time. The VS time control signal or the instants of communication via SPI bus then allow the

recognition of TDC-ignition.

  At time Z-OT, the incoming regulator 2, 3 then causes the current or the coils under consideration to be supplied with current. The gas change valve a, 5b, 6a, 6b remains closed, however, since at TDC-ignition, the pressure in the cylinder is very high. From the stroke signal of the valve adjusting device 5a, 5b, 6a, 6b, the inlet regulator 2, 3 can then read the valve clearance. The value thus determined, corresponding to the valve clearance, is then taken into account when regulating the incoming supply. Optionally, a value which has been determined for the first time can be updated adaptively by means of other controls and, for example when a certain limit value is crossed, a fault signal can be sent to

communication computer 1.

  Advantageously, independent inlet regulators 2, 3 are provided for the intake valves 5a, 5b and for the exhaust valves 6a, 6b of each cylinder, but another distribution is however also possible, a single arrival regulator that can notably meet the required conditions. Furthermore, in addition to a communication computer 1, at least one other communication computer can also be provided, a clean communication computer which can, for example, be provided for all the intake valves 5 and another for all the intake valves. exhaust 6 of the internal combustion engine. This arrangement makes it possible to obtain a certain redundancy, since in the event of failure of one of the communication computers, the other can take

  in charge of the tasks of the faulty computer.

  The invention has been explained with the aid of safety valves.

  change of electromagnetically actuated gases.

  However, it is not limited to such actuation of the valves, but it can also be applied in the case of any other principles of actuation independent of a camshaft, for example in the case of change valves. gas operated hydraulically.

Claims (10)

  1. Method for determining the valve clearance of a gas change valve of a cylinder of an internal combustion engine which is actuated by an adjustment device independently of a camshaft and which is controlled by a device control to which a switching signal is sent, which indicates the opening or closing of the gas change valve, and a crankshaft position signal from which the crankshaft position can be deduced, characterized in that a) the instants the cylinder top dead center is determined from the crankshaft position signal or the switching signal, b) the cylinder top dead center at which a mixture ignites is determined from the switching signal or the position signal crankshaft and, c) in at least one of these top dead centers of the cylinder at which a mixture ignites, the control device takes the valve clearance as being the clearance between the adjustment and gas change valve. 2. Method according to claim 1, characterized in that at the top dead center, the adjustment device is in an end position and is released from   this end position in step c).   3. Method according to any one of   claims 1 and 2, characterized in that a signal   stroke indicating the stroke of the gas change valve is produced and the valve clearance is determined by step   c) using the race signal.   4. Method according to any one of   Claims 1 to 3, characterized in that the pressure valve   gas change is actuated by electromagnetic means and in that there is provided an inlet regulator, which controls at least this gas change valve according to the switching signal, and a communication computer which , from the crankshaft position signal, produces the switching signal intended for the arrival regulator, while the arrival regulator executes steps b) and c). 5. Method according to claim 4, characterized in that the inlet regulator takes account of the determined value corresponding to the valve clearance, in order to ensure a smooth and noiseless arrival of the gas change valve in the positions end. 6. Method according to any one of   Claims 1 to 5, characterized in that the signal   crankshaft position is derived from a CAN bus signal. 7. Method according to any one of   Claims 1 to 4, characterized in that the signal   crankshaft position is derived from a SPI bus signal. 8. Method according to any one of   Claims 1 to 7, characterized in that a signal   binary whose level change is associated with opening or closing of the gas change valve, is used as a switching signal, one signal level being associated with a closed gas change valve and the other level signal   being associated with an open gas change valve.   9. Method according to any one of   claims 5 to 8 when dependent on the   claim 4, characterized in that the value corresponding to the valve clearance is updated by adaptively.   10. Method according to any one of   claims 1 to 9, characterized in that in step a), the   top dead centers are determined exactly over time and, in step b), a recognition of those of top dead centers at which a mixture lights up.