DE19653193A1 - Circuit arrangement for detecting position of motor vehicle gear selection lever - Google Patents

Abstract

The circuit arrangement detects the position of a selection lever (15) which is adjustable between several positions. The position of the lever is detected by a detection arrangement (1) and transmitted over a signal line (7) as a position signal to a gearing control mechanism (2), to trigger a function corresponding to the respective position. The position signal is binary coded and comprises an amount of bits necessary for the representation of the possible number of lever positions. The detection arrangement is connected with the gearing control mechanism through an additional output signal line (10), over which a further coded signal is transmitted. This coded signal contains a redundant information about the drive area, and bit errors in the position signal are recognised and corrected by the gearing control mechanism, using an evaluation of the coded signal.

Description

The invention relates to an arrangement according to the preamble of claim 1. Such arrangements are used to detect the Position of a selector lever or shift lever in one force vehicle that can be moved between several positions or is arranged pivotably and its position by a Detection device is detected and via a data line is transmitted to a control unit to one of the respective trigger appropriate function in the current position.

Automatic transmissions of passenger cars are becoming increasingly popular electronically controlled. An important input for the electronic transmission control is that of the car driver using the selector lever. Of the Range selector lever can be between five driving positions, for example area positions are moved back and forth, the assigned detection device between five driving range positions lungs and the intermediate positions (park, Return, Neutral, Drive, Low and intermediate positions Z1 to Z4) must differentiate.

The possible driving ranges are recorded by a so-called position detection switch, the position or the angle of the selector lever or the position of through components operated by the selector lever (for example components transmission hydraulics). By failure functions of the position detection switch it can be a Falsification of the position signal and thus possibly serious malfunction of the electronic gear taxation coming.

With the electromechani used so far on a large scale position detection switches (e.g. DE 34 34 205 A1) there is contamination on the contact-forming or Si  gnale receiving elements to temporary contact errors and thus falsifying the position signal. This temporary Contact errors disappear after some time or after one further actuation of the selector lever.

The invention has for its object a circuit order for detecting a lever position in a motor vehicle create stuff whose function even during temporary Si Signal errors, especially temporary contact errors, largely remains intact. This is supposed to be an emergency operation, for example of an automatic transmission and costly workshop stays are avoided.

This object is achieved by a circuit solved order according to claim 1. Appropriate further training the invention are laid down in the subclaims.

The advantages of the invention are in particular that by an additional output signal line from the position server identifier a redundant code signal that an assignment allows a bit pattern for a driving area, be is provided. Due to a contact error, after as before a bit at the output of the position detection switch falsified, but the control unit cannot do this error only recognize, but also correct, d. H. the actual Detect the driving area. An error diagnosis will result in au It also checked whether the corresponding bit was only temporarily (tem porous error) or is constantly disturbed. Temporary errors can be corrected again and again, only in the case of one permanent fault, the error must be remedied.

An embodiment of the invention will follow hand of the drawing explained. Show it:

FIG. 1 shows a circuit arrangement according to the invention as a block diagram;

Fig. 2: a ver used in the circuit arrangement of Figure 1 position detection switch in a Be tenansicht;

Fig. 3: a contact plate of the position detection switch of FIG. 2;

FIGS. 4 and 5: a contact spring of the position detection tenansicht in the plan view and Be switch of Fig. 2.

A circuit arrangement for detecting the position of a selector lever has a detection device 1 , which is also referred to below as a position detection switch 1 ( FIG. 1). The selector lever itself is not shown in the block diagram of FIG. 1. If nine positions of the selector lever can be seen, the position detection switch 1 is designed to generate a five-bit code signal. This signal is transmitted to an electronic transmission control 2 and arrives there at a filter circuit which is formed as a filter 3 against short-term transients. Such short-term transients can arise, for example, from a contact bounce in the position detection switch 1 .

In addition to the filter 3, the electronic transmission control 2 contains an error detection and correction circuit 4 , a control 5 for controlling transmission functions and an error diagnosis circuit 6 . The output signal of the position detection switch 1 passes via a first or output signal line 7 to the electronic transmission control 2 and in this to the filter 3 . The signal filtered therein then passes via a second signal line 8 to the error detection and correction circuit 4 , and the signal corrected therein reaches the driver 5 via a third signal line 9 . The signal lines 7 and 8 are designed as multiple lines over which a number n bits are transmitted in parallel. In the present example, five bits are transmitted via the signal line 7 (n = 4 + 1 =) and five bits are transmitted via the signal line 8 .

In the control 5 , the corrected signal is linked to other signals influencing the selection of the gear ratio - which are not important in the context of the present invention - and then control signals are generated for the gear which, for example, cause a change in the gear ratio. An additional output signal line 10 is used to transmit a code signal, which contains redundant information about the driving range, to the transmission control 2 .

The electronic transmission control 2 reads the digital output signal of the position detection switch 1 at periodically small time intervals - for example 10 ms. This signal is cleaned of short-term transients ("contact bounces") by filter 3 using known methods. This generally does not affect temporary contact errors.

The filtered signal on the signal line 8 is processed in the error detection and correction circuit 4 . Here, temporary contact errors are recognized and corrected. The corrected signal on the signal line 9 is then available for the control of transmission functions, for this purpose it is transmitted to the control 5 .

The corrected signal generated in the error detection and correction circuit 4 passes through a fourth signal line 19 to the error diagnosis circuit 6 , in which it is checked whether the duration of the occurrence of a contact error lies within predetermined values.

The binary coded output signals (so-called bit pattern Co position detection switch (bit A to bit E) are shown in Table 1. In addition is as a Bit S represents a so-called starter lock signal. This Signal deactivates the starter lock for starting the engine in the Positions P and N of the selector lever and is also used for the mis ler detection and correction used.  

In Table 1:

• 0 a contact is closed to ground
• 1 a contact is open to ground

Table 1

Error detection and correction is carried out using the Table 1 removable signals performed as follows. Con Clock errors can be statistically independent of each bit occur to each other. According to the usual procedure in the Automotive technology only become simple errors (a contact error only occurs with one bit). Through a con clock error occurs in the output signal instead of a "0" (Contact against ground closed) an "l" (contact against Mass open).

The error detection and correction circuit 4 reads the ge filtered signals and implements them in accordance with an assignment rule, which is shown in the following table 2 as an assignment table, in a corrected signal. The assignment table contains all the bit patterns of table 1 and also the bit patterns resulting from contact errors (single error "0" becomes "1").

Table 2

If the bit pattern read corresponds to a driving range, then it is output as a corrected signal. Otherwise a contact error is recognized and this is shown in Table 2 corrected signal output. With some bit patterns must In addition, the bit S can be queried in order to identify a unique Make a decision between two possible cases.

When using this assignment table, this results in the error behavior shown in Table 3 below.

Table 3

Here mean:

LL X a contact error on bit X (bit X becomes 1 = contact open)
0 code word remains the same
- Code word changes to code word for previous position
+ Codeword changes to codeword for the following position
FK corruption of the code word; Errors are recognized and corrected
FKS falsification of the code word; Error is recognized and corrected after evaluating bit S.
FDL corruption of the code word; Fault is recognized, driving range cannot be clearly determined, but can be limited to driving range D or L.

If a bit pattern goes through a contact error in that for the previous or following position, the elec tronic transmission control alone is not a mistake know. Depending on the type of gearbox, however, the diagnosis other transmission signals (e.g. by checking the speeds an error can be detected in the gearbox).

In the event of a contact error on bit D in the "Drive" driving area or by bit E in the "Low" driving range, the elektroni cal transmission control a fault that is not clearly correct can be rigged (a decision between the Fahrbe range D and L is not possible based on the bits alone). In In all other cases, temporary contact errors can be corrected be greeded.

The fault diagnosis circuit 6 is used to check the duration of the occurrence of a contact fault in order to report a possibly permanent fault if a defined period of time is exceeded. A temporary error memory is used for this. A counter is available for each cause of the error (contact error bit AE). Table 4 below shows the structure of the temporary fault memory.

Table 4

If an error is detected, the cause of the error is assigned table and an entry is made to the ent speaking point of the temporary error memory, namely by incrementing the counter reading.  

The counters are set to zero as soon as the corresponding position in the filtered signal is "0". The tough Readings are checked periodically. If exceeded an error message appears if certain limit values are reached. So that will a permanent fault is detected and reported, d. H. the mistake must be repaired in the workshop. On the other hand, tempo Rare errors, as already mentioned, by the invention Circuitry are corrected again and again.

The position detection switch 1 ( FIG. 2) consists of a contact plate 11 , over which a multi-element contact spring 12 is moved back and forth. The contact spring 12 is attached to a sliding carriage 13 , which leads in a housing 14 ge and with a selector slide or selector lever 15 is connected ver. This selector slide or selector lever 15 represents the actuating device with which the driver of the motor vehicle selects the driving range. The reciprocating movement of the selector slide 15 is indicated by a double arrow.

The contact plate 11 consists of an electrically insulating base material 16 , in which contact tracks 17 and 18 are provided made of an electrically conductive material ( FIG. 3). The contact track 17 forms the mass, the six contact tracks 18 are used to generate bits A to E and S.

The contact spring 12 is mehrgliedrig formed (Fig. 4), it has, for each of the contact paths 17 and 18, a contact finger 19, that is, in the present example a total of seven contact fingers 19.

The contact fingers 19 of the contact spring 12 are bent twice, as can be seen from FIG. 5. The contact springs 18 connected by the contact spring 12 depending on their axial position on the contact plate to ground are supplied as bits A to E via the signal line 7 and as bit S via the additional signal line 10 to the filter circuit 3 , in which the signal processing already described takes place .

Claims (5)

1. Circuit arrangement for detecting the position of a selector lever ( 15 ) or shift lever in a motor vehicle,

• - The slidably arranged between a plurality of positions or ver, and
• - whose position is detected by a detection device ( 1 ) and transmitted via a signal line ( 7 ) as a position signal to a transmission control ( 2 ) in order to trigger a function there corresponding to the respective position,
  characterized by
• - That the position signal is binary coded and has a number of bits (AE) necessary to reflect the possible number of lever positions,
• - that the recognition device (1) is connected by an additional output signal line (10) through which a further code signal is transmitted to the transmission control (2),
• - That this code signal contains redundant information about the driving range, and
• - That by the transmission control ( 2 ) on the basis of an evaluation of the code signal, bit errors in the position signal are recognized and corrected.

2. Circuit arrangement according to claim 1, characterized in that the transmission control ( 2 ) with a filter ( 3 ) is seen ver, by the short-term transients occurring on the signal line ( 7 ) from the position signal who filtered out the. 3. Circuit arrangement according to one of the preceding claims, characterized in that the position signal is supplied to an error detection and correction circuit ( 4 ) in which temporary signal errors are recognized and corrected. 4. Circuit arrangement according to one of the preceding claims, characterized in that the transmission control ( 2 ) is provided with a fault diagnosis circuit ( 6 ) by which it is checked whether the duration of the occurrence of a signal error remains within predetermined values. 5. Circuit arrangement according to one of claims 3 or 4, characterized in that by the error detection and correction circuit ( 4 ) the filtered signals according to an order regulation according to the following table are converted into a corrected signal:
wherein:
a bit = 0 a contact closed to ground and
one bit = 1 one contact open to ground
mean.