DE3307833C2 - Method for displaying and / or storing errors in sensor arrangements on internal combustion engines - Google Patents

Description

The invention is based on a method according to the genus Main claim. Especially with 5-cylinder internal combustion engines for electronic ignition systems for cylinder recognition except one of the reference mark signal taken from the crankshaft Phase signal necessary. The phase signal generator is with the Coupled camshaft and usually as inductive, optical or Hall sensors designed in ignition distributor. About these encoder arrangements then often comes a speed sensor, whose signals through a gear coupled to the crankshaft are generated. Such Complicated encoder systems can also be used for complex ones Fuel injection systems or other control systems use Find.

If an error occurs in the system, it is often difficult determine on which error which encoder arrangement this Error is due. By recognizing the right error can then an unnecessary encoder replacement, an unnecessary cable repair or an unnecessary replacement of the control unit in the workshop be avoided. For example, if a reference mark signal during a phase signal should appear if it functions properly, but it only appears afterwards, this can have various causes have: loose contact of the phase signal or loose contact of the Reference mark signal or rotation of the distributor.  

In the generic JP-OS 142 233/80 is a simple one Diagnostic device for an encoder arrangement, the rotational movement detects the crankshaft of an internal combustion engine, described. The Encoder arrangement consists of a speed encoder and a Reference markers. The speed sensor gives the at one revolution Crankshaft an angular pulse every 2 °. The reference mark giver gives one after every revolution of the crankshaft after 120 ° Base pulse. These basic pulses become a first counter fed. The angle pulses are generated by a 60: 1 coaster reduced. The reduced angular pulses are from a second Counter counted. The counting results of both counters become one Comparator fed. The comparator places a deviation between the two meter readings, he gives a corresponding one Signal to an AND gate. Another input of the AND gate a base pulse is applied. With the help of the AND gate that is logical product of the input signals of the AND gate formed. The signal present at the output of the AND gate is considered as Evaluation size used for the encoder arrangement. If due non-regular base or angular pulses are the output variables of the Counter does not match or the crankshaft is stationary the signal present at the output of the AND gate is low Level state on. By using this signal to control a Display means can be used in a simple manner diagnosed whether the encoder arrangement works regularly or Not.

From DE-OS 32 73 913 is a system for detection, storage and display of various errors from encoders and switching devices in Motor vehicles known. However, there are only mistakes made by individuals Components displayed by limit value queries, but not the Causes of errors, especially when several work together Components (e.g. encoder arrangements, especially pulse generators).

The inventive method with the characterizing features of The main claim has the advantage that when a Error this not only appears, but initially its possible causes are examined. Only when the cause is identified the error can then be clearly identified, d. H. especially when several components interact that component (encoder arrangement) are designated that is responsible for the error. So besides total defects, such as short circuits or interruptions Loose contacts and angular errors of the encoder arrangements to each other be recognized. Reading or reading the stored errors in the workshop, this makes it easier to correct the error and avoids the unnecessary replacement of components.

By the measures listed in the subclaims advantageous developments and improvements in the main claim specified procedure possible.  

An embodiment of the invention is in the drawing shown and in the description below explained in more detail. Show it

Fig. 1 is a schematic diagram of a control unit for an internal combustion engine, which is connected to various rotating encoder arrangements, Fig. 2 is a signal diagram for explaining proper signal sequences of the encoder arrangements, Fig. 3 is a flow chart for explaining the error check and Fig. 4 Flow chart for a more detailed representation of the error check of speed signals.

In the exemplary embodiment shown in FIG. 1, a control device 10 designed as a microcomputer is shown, which controls ignition and injection output stages 11 on the output side. On the input side to this control are device 10 rotational speed signals n a speed sensor 12, reference mark signals r of the crankshaft and coupled to the speed sensor 12, reference marks encoder 13 and phase signals p of the cam shaft of the internal combustion engine connected to the phase sensor 14 is supplied. These sensors can be inductive, optical or Hall sensors. The control device 10 not only contains the control functions for the ignition and / or the fuel injection of the internal combustion engine, but also also contains a diagnostic system for the sensor arrangements 12 to 14 . The result of the diagnosis is stored in one of the memories of the microcomputer and can be identified immediately or later in the factory instead of on the display device 15 . The display device 15 can consist of control lamps for the various types of errors, a display for direct identification of the errors, a measuring instrument or another device for differentiating the various errors. Methods for storing errors and displaying errors are described in more detail in the prior art specified at the outset and are therefore not described again in detail.

The signal diagram shown in FIG. 2 shows the position of the various encoder signals relative to one another. In this case, the speed sensor 12, in particular a tooth sensor, generates a large number of speed signals per revolution of the crankshaft, for. B. 135. The reference mark generator 13 generates a reference mark signal r per revolution of the crankshaft, so that the distance between two reference mark signals corresponds to a number Z of speed signals n. The coupled with the camshaft phase signal generator also generates a phase signal P per revolution of the camshaft, so that this phase signal P occurs once every second crankshaft revolution and then - if it functions properly - must coincide with a reference mark signal r.

The phase signal has a signal width of Zp Speed signals. This is usually in the distributor arranged phase signal generator is for cylinder detection required for five-cylinder engines.

By logically combining the three signals n, r and p with each other it is possible, except for the absence these impulses or pulse sequences are also the right ones Position of the signals r and p to each other and thus the rich Detect and display the current setting of the distributor demonstrate. There may also be a loose contact on the encoder cables in addition to the static error of the respective Pulse train recognized and displayed again accordingly will. This test can be logically linked in an existing microcomputer of a control unit self-diagnosis in the program sequence contains queries according to the specified state of the art. The test procedure can precede the actual control gear (ignition, injection) upstream, the test procedure or the test program and the main program can be nested, or the test program can be run cyclically during the main pro gramms can be called.

In the flow chart shown in Fig. 3, the test sequence is explained, the most important criterion is that certain errors in the timing of the signal sequences can have multiple causes and therefore an error is only stored and displayed if it is clearly a certain signal or can be assigned to a specific cause. After the start ( 20 ) of the test sequence in the microcomputer 10 , initialization ( 21 ) takes place in the usual way, ie all errors are cleared and all registers, flip-flops and counters are reset. Then a speed error ( 22 ) is set in advance. This speed error is referred to as n-error 1 , which is cleared again after the appearance of an n-edge ( 23 ) ( 24 ). A special error possibility for the n signal is still checked in a special test sequence ( 68 ), which is described in more detail in FIG. 14.

After the n-error 1 has been deleted ( 24 ), an "n-counter" in the microcomputer 10 is set to the value zero ( 25 ) for testing the phase signal. This counter - four more are required - can also be registers of the microcomputer, but the summation can also take place in the accumulator, with the results being stored in memory cells. Now the n-counter is increased by the value 1 ( 26 ). An edge of a phase signal is then waited for ( 27 ). If there is no p-edge, a query is made as to whether the n-counter contains a value that is greater than 4Z + K ( 28 ). 4Z corresponds to four crankshaft revolutions, ie two phase signals should occur in this interval, the absence of a p-signal being initially tolerated for the test. If there is no such tolerance, the value 2Z would have to be requested instead of 4Z. K is a tolerance factor. If the condition ( 28 ) is not met, the n-counter is increased again by the value 1 ( 26 ). As long as there is no p-edge, this process continues until the value 4Z + K is reached, as a result of which a phase error signal (p-error 1) is stored ( 29 ) and possibly displayed. This error signal indicates that either the phase signal generator 14 is defective or that there is an open circuit or a line short circuit. It is then not possible to control the ignition and / or injection.

If, on the other hand, a p-edge occurs ( 27 ), the system waits until the phase signal assumes the value 0 ( 30 ), ie until the beginning of a phase signal is reached (the phase signal is a 0 signal). It is now checked whether a reference mark signal r is present. To do this, the n-counter is set to the value 0 ( 31 ) and then increased by the value 1 ( 32 ). It will now appear that a reference mark signal r is queried ( 33 ). If there is no reference mark signal r, this query takes place while the n-counter ( 32 ) is continuously increased as long as the phase signal ( 34 , p = 0) is present. First of all, it is assumed that a reference mark signal r appears correctly during this phase signal ( 33 ).

It is now checked whether there is a loose contact (p-error 2 ) of the phase signal. For this purpose, it is checked whether the following reference mark signal r is properly present by the phase signal generator 14 , that is, the phase signal does not have the value 0. To do this, the n counter is first set to zero ( 35 ). The n-counter is then increased by the value 1 ( 36 ) until the value ZK is reached ( 37 ), that is to say a numerical value which corresponds to the distance between two reference mark signals r minus a correction factor K. If this value is exceeded, the appearance of a reference mark signal r is awaited ( 38 ). This is done by continuously running the loop ( 36 to 39 ) and increasing the n-counter ( 36 ) until the value Z + K ( 39 ) is exceeded. If no reference mark signal r has appeared between ZK and Z + K, then there is an error that cannot be examined in this test step (i.e. it cannot be clearly determined whether a reference mark is missing or whether speed impulses are missing due to a loose contact) and the test procedure continues with procedural step 24 . On the other hand, if a reference mark signal r ( 38 ) appears in the specified interval, the signal level present at the phase signal generator 14 is examined ( 40 ). If this signal level is properly equal to 1, then in a manner that is not shown in more detail with the main program, ie with the program for generating ignition, injection or other control signals. If, on the other hand, there is a signal level of 0, a phase error signal (p-error 2 ) is generated ( 41 ), which indicates that an incorrect phase signal is present, which is very likely to be due to a loose contact.

The following description starts again at loops 32 to 34 . If there is still no reference mark signal r at the end of a phase signal ( 34 ), it is checked whether there is a reference mark error. For this purpose, the n-counter, which currently contains the value Zp, is further increased by the value 1 ( 42 ). The occurrence of a reference mark signal r ge is then checked again ( 43 ). A loop ( 42 to 44 ) is used to wait until the numerical value 2Z + Zp is reached ( 44 ). This numerical value corresponds to twice the distance between two reference mark signals plus the numerical value Zp, which corresponds to the signal width of a phase signal. Here again, the absence of a reference mark signal is initially tolerated. If such a tolerance is not to take place, the loop ( 42 to 44 ) only remains up to the numerical value Z + Zp. If the numerical value is reached, a reference mark error signal ( 45 ) is stored and, if necessary, displayed, which indicates the defect in the reference mark generator. A possibly saved angular error is then deleted ( 46 ), which will be discussed later.

If, on the other hand, a reference mark signal r occurs during a passage through the loops 42 to 44 ( 43 ), it is now more checked whether there is an angular error, that is to say whether the reference mark signal is incorrectly rotated angularly relative to the phase signal. This can e.g. B. include a rotation of the distributor. First, another n1 counter is set to the value 0 ( 47 ). Then it is queried whether the first n counter has exceeded the value Zp ( 48 ). This should actually be the case since this counter has already counted signals during the past phase. If there is a value smaller than Zp, there must be another error and the test starts again at step 24 . If, on the other hand, the numerical value Zp is exceeded, the occurrence of a reference mark signal r is again waited for ( 49 ). This wait is carried out in a loop ( 49 to 51 ), increasing the n1 counter by the value 1 ( 50 ) until the numerical value 2Z + K is exceeded ( 51 ). If this is the case, there is a reference mark error that is being saved ( 45 ). On the other hand occurs during the passage of the loop (49 to 51), a reference mark signal r in (49), so it is queried whether this reference mark signal has occurred at the correct distance to the previous (52). The correct distance is Z, again allowing a tolerance of at least ± 1. If the correct distance is not given, there is another error and the test starts again at step 24 . If, on the other hand, the distance is correct, a query is made as to whether a phase signal p = 0 is present at the same time ( 53 ). Since the previous reference mark signal ( 43 ) had not coincided with a phase signal, a phase signal should now be present if it functions properly. Consequently, if there is no phase signal ( 53 ), an angular error (α error) is stored and possibly displayed ( 54 ), which indicates that there is an angular error between the reference mark and the phase, which is in particular due to a rotation of the distributor.

In the flowchart shown in FIG. 14, the test sequence ( 68 ) schematically shown in FIG. 3 for detecting a speed signal error is shown in more detail. The purpose of this arrangement is to store a further speed error (n-error 2 ) and to maintain the storage even when a speed signal occurs later, if immediately after switching on the power supply a regular sequence of p and r signals but no speed signal n occurs. It can happen that when the power supply is switched on by signal bouncing or other switch-on disturbances, reference mark and phase signals are fooled without speed signals already being available at this time. If, on the other hand, the speed signals are actually only used after a few periods of correct reference mark and phase signals, then there is a speed error that initially appears to have been remedied when speed signals reappear, but basically contains an error in the speed sensor that must be followed up. For this purpose, a certain number of reference marks and phases are checked for their correct sequence and a speed error is only stored if no speed signal has still occurred in this correct sequence.

If a speed signal edge ( 23 ) is not present, a phase signal edge is therefore initially waited for ( 55 ), specifically a phase signal edge at the beginning of a phase signal ( 56 ). Then a phase signal counter is incremented by the value 1 ( 57 ). Then the state of the phase signal generator 14 is queried ( 58 ), which has a 0 signal at this point in time. Then a loop ( 59 to 63 , 58 ) waits for the occurrence of a reference mark signal r ( 59 ). If a speed flank occurs during such a run ( 62 ), no speed error signal is additionally stored and, in the manner already described, step 24 clears the already set speed error signal (n-error 1 ). If a reference mark signal now occurs ( 59 ), a reference mark counter which only counts when p = 0 is ( 64 ) increased by the value 1. If in one of the subsequent runs of the described loop ( 58 to 63 ) the phase signal ends ( 58 ), then a reference mark signal r is again waited in the test step ( 65 ). The waiting loop now consists of steps 60 to 63 , 58 , 65 . If such a reference mark signal now occurs, a reference mark counter which only counts when p = 1 ( 66 ) is increased by the value 1. This alternating traversal of the two loops described continues until the condition specified in step 60 is fulfilled, ie until the reference mark counter (p = 0) has the value 2 and the reference mark counter (p = 1) has the value 1 and the phase signal counter ( p-counter) has the value 3. The phase signal counter ( 57 ) is increased whenever a p-edge occurs during a loop pass ( 63 ). If the condition set in step 60 is met - it has been achieved with the proper sequence of signals p and r according to FIG. 2 at time t1 - then a speed error signal 2 is stored ( 67 ) which, in contrast to speed error signal 1 ( 22 ), is no longer is deleted by step 24 . It indicates that when the control device 10 is switched on, an irregular speed of the speed signals is present or that the speed signal has been missing for a certain time when the motor is running due to a loose contact. If, on the other hand, this prescribed sequence of the p and r signals according to FIG. 4 is not adhered to, then it must be interference and bounce signals, the speed error signal 2 is not generated and a speed edge ( 23 ) is still waited for.

It should also be pointed out that the transmitters 13 and 14 described can emit several signals per revolution instead of one signal. In the case of multi-cylinder internal combustion engines in particular, this depends on whether further signals required are to be generated internally electronically or by the transmitter arrangements. Furthermore, it should also be mentioned that the control device 10 for calculating control signals can of course also be supplied with other required parameters in a known manner. This is symbolically represented by the arrow PM Darge.

Claims (14)

1. A method for displaying and / or storing errors in sensor arrangements on internal combustion engines, wherein at least one reference mark (r) is generated per revolution by a first signal transmitter ( 13 ) coupled to a shaft, and wherein at least one second signal transmitter ( 14 ) generates further signals are generated, which are in a fixed association with the signals of the first signal generator ( 13 ), deviations from a prescribed sequence and prescribed intervals of reference marks (r) and further signals (p, n) are detected and then at least one error signal is generated , which is stored and / or fed to a display device ( 15 ), characterized in that the cause of the error is determined by evaluating the deviation from the prescribed sequence and prescribed intervals of reference marks (r) and further signals (p, n) and that Error signal is specified, which component of the encoder arrangement for the au error is responsible. 2. The method according to claim 1, characterized in that the first signal generator ( 13 ) is coupled to the crankshaft of the internal combustion engine and the second signal generator ( 14 ) for generating phase signals with the camshaft. 3. The method according to claim 1, characterized in that every nth (n2) Reference mark signal during a relatively longer one Phase signal is generated and that if there is a deviation from this prescribed coincidence outside a predeterminable tolerance Error signal is generated.   4. The method according to any one of the preceding claims, characterized in that the signal distance between two signals with the aid of speed signals (n) higher frequency of a speed increment encoder ( 12 ) is counted and that an error signal for the signal to be tested is generated when a predetermined numerical value is exceeded . 5. The method according to claim 4, characterized in that for Verification of a phase signal (p), which after a coincidence with a reference mark signal (r) on the subsequent reference mark signal speed signals must not occur from the first Reference mark signal are counted and that at the following Reference mark signal and simultaneously occurring phase signal Phase error signal is generated. 6. The method according to any one of claims 3 to 5, characterized characterized in that speed signals (n) from the first edge of a Phase signal (p) are counted and that when a Reference mark signal (r) before reaching a numerical value (Zp), the corresponds to the length of a phase signal, no error signal generated and advance to the next test step. 7. The method according to claim 6, characterized in that at Reaching a predeterminable numerical value that is at least that Signal distance (Z) between two reference mark signals (r), without a reference mark signal occurring, a Reference mark error signal is generated. 8. The method according to claim 7, characterized in that the Occurrence of a reference mark signal before reaching the predeterminable Numerical value another counting process of speed signals is initiated, and that when another numerical value is reached, the at least the signal distance between two reference mark signals corresponds without another reference mark signal (r) having occurred would be, a reference mark error signal is generated.   9. The method according to claim 8, characterized in that the Occurrence of a reference mark signal at the intended distance during the further counting process and the simultaneous absence of one Phase signal an angle error signal is generated. 10. The method according to any one of the preceding claims, characterized characterized in that at the beginning of the test process Speed error signal is generated that when a Speed signal edge is deleted again. 11. The method according to claim 10, characterized in that the Occurrence of phase and reference mark signals and missing Speed signals a prescribed order of phase and Reference mark signals are queried and that when these are present prescribed sequence another speed error signal is produced. 12. The method according to claim 11, characterized in that the further speed error signal even when Speed signals is retained. 13. The method according to any one of the preceding claims, characterized by the implementation in a microcomputer ( 10 ). 14. The method according to claim 13, characterized in that a shared microcomputer for review and / or storage and the control functions for the internal combustion engine are provided becomes.