DE10237245B4 - Method for gear monitoring for an automatic transmission of a motor vehicle - Google Patents

Abstract

method for gear monitoring for a Automatic transmission of a motor vehicle, in which the individual gears through the combination of two or more switching elements (A, B, C, D, E) are realized, characterized in that each switching element (A, B, C, D, E) a symptom counter (Nx) whose value is given when a malfunction occurs in a gear in which the switching element is involved, is incremented by one, where if a given limit value for the symptom counter (Nx) is reached, this switching element or the corresponding switching system clearly identified as defective and the transmission in a final emergency and where if the default threshold for the symptom counter (Nx) is not reached, is switched to a replacement gear, where only the corridors are switched, where the clearly recognized as defective switching element or the corresponding switching system is not involved.

Description

The The present invention relates to a method of gait monitoring for a Automatic transmission of a motor vehicle according to the preamble of the claim 1.

Safety systems for automatic transmissions are known from the prior art. For example, under the DE 196 01 618 A1 the Applicant proposed to detect malfunctions outside the circuits by monitoring the measured transmission input and output speeds. Subsequently, a change is made from the current gear into a substitute gear which, if possible, is the next higher gear; If the current gear is the highest then it will shift to the next lower gear. As part of the DE 196 01 618 A1 For each gear, a symptom counter is provided, which is incremented by one in the presence of a malfunction, wherein an emergency driving program is activated when a predetermined limit value for the symptom counter is exceeded.

These The prior art approach results in transmission systems, where a clutch or brake in multiple gears in a row is switched, in case of malfunction of one of these switching elements or switching systems in multiple circuits and subsequent detection of malfunctions, before a safe operating condition is achieved. Here is under Switching system the entire chain from the control to one To understand switching element, so that it is a malfunction e.g. to a faulty specification of the control to a faulty Current-pressure conversion to a malfunction in the valve system or also to a malfunction of a component of a switching element or an oil leak can act. The same applies to transmission systems with always recurrent connection of the same switching element in the next gear, in which case for a safe state is achieved for a short time; however, it will be from the system at the next Up or down again tried a switching element with no longer existing function into the power flow.

Of the The present invention is therefore based on the object, starting from the cited prior art, a method for gait monitoring for a Automatic transmission of a motor vehicle indicate which the disadvantages of the prior art avoids. The inventive method should also be for Transmission with multiple use of clutches and brakes and their Activation be used.

Especially is intended as part of the process, a malfunction of a switching element be detected and assigned to this switching element. On this way you can repeatedly occurring safety-critical conditions largely avoided become; Furthermore In this way, the availability of the Vehicle increased.

moreover should ensure a quick response to a malfunction and the transmission are effectively protected from damage or destruction.

These The object is solved by the features of claim 1. Further Variants and advantages will become apparent from the dependent claims.

Therefore It is proposed that each switching element of the transmission a symptom counter Nx whose value should occur in the event of a malfunction Gang, in which the switching element is involved, increments by one where, when a predetermined threshold for the symptom counter Nx is reached, this switching element or the corresponding switching system clearly identified as defective and the transmission in a final emergency switched without participation of this switching element and wherein if the default limit for the symptom counter Nx is not reached, is switched to a replacement gear.

Of the final Emergency gear can according to the invention, if the needed Circuit possible is to be placed directly or via the filing of a secure Condition by a gear layout and opening the transmission and the subsequent Change in the not directly to be switched spare gear by a appropriate gear engagement can be realized.

Should an emergency gear will be necessary, the several gears under the current gear If the malfunction has occurred, the emergency will be activated only after falling below suitable speed thresholds for this Emergency gear engaged to avoid the risk of inadmissible speeds. As long as the speed thresholds are not undershot, is preferably switched to the "neutral" state.

The inventive method has the advantage that in most gears immediately after egg nem recurrence of an error, the defective switching element or switching system is determined and a reaction is initiated. This is the fastest way to determine the defective switching element, since the involvement of two switching elements in each gear requires a further occurrence of a malfunction in order to uniquely determine the defective switching element.

By the assignment of the error to a switching element or switching system is a targeted reaction possible; this is an important difference from the prior art, in which the malfunction is assigned to the gear. The detection of a malfunction in a gear per se can be carried out according to the prior art.

The The invention will be described below by way of example with reference to the accompanying drawings explained in more detail. It represent:

1 : A representation of the most important steps of the method according to the invention with reference to a flowchart;

2 : A schematic representation of a six-speed transmission;

3 : That according to the gearbox 2 corresponding circuit diagram; and

4 : A table containing the replacement gears as a function of the faulty gears.

According to the invention Each switching element is a counter assigned its value - starting at zero - at any occurrence of a malfunction in a corridor in which this Switching element involved is increased by one.

To Each switching element has a limit for its counter, the preferred from the number of involved in a gang switching elements and the number of gears, in which this switching element is involved depends. In other words, corresponds to the limit of the number of gears with malfunction that exist have to, to clearly identify a defective switching element. If For example, a switching element in two gears is involved and for this Gears each two switching elements are activated, then the limit is two, because so the defective switching element is clearly identifiable.

According to 1 , which illustrates the procedure in the event of a malfunction in a forward gear, is provided to increase the counter associated with one of the switching elements associated with the occurrence of a malfunction in a gear. These counters are shown in the figure with Nx, where x denotes the respective switching element.

If the value of the counter Nx for a switching element exceeds the predetermined limit, then a Circuit in a final Emergency started, whereby, depending on the situation, first to "Neutral", inadmissible to avoid high speeds or if a circuit over several Gears necessary is. Optionally, this can be entered in the diagnostics administration.

If the limit for the counter not exceeded was, then a circuit is carried out in a spare gear. Of the Replacement gear is according to the invention the next higher gear with the exception of the replacement gear for the highest gear, the next lower Gear is when the speed allows it. If in the context of the subsequent query according to the driver's request, the driver's request not the malfunction corresponding gear and the driver's request the next higher gear is, then is switched according to the driver's request.

If above conditions not met then the replacement gear is retained until a new driver request is generated; In this case it will be checked again if the Driver's request does not correspond to the malfunctioning having gear and the replacement gear the next higher gear is etc.

Then follows the query of the driving position. If the position is N, P or R, then the normal function is transferred, otherwise, as already explained, the replacement gear with the Driver's request and go through this loop again.

In 2 is a gearbox with a converter 1 , a converter clutch 2 and five switching elements, namely three clutches A, B, E and two brakes C and D shown. The corresponding to this transmission Schematic is the subject of 3 , The circuit diagram can be seen that in each case two switching elements are involved. Here, N1-N6 designate the gear tracking in "neutral." Here, too, the gear is given in accordance with the gear to be engaged in the driving position.

In this transmission is in accordance with 4 if the counter Nx is smaller than its limit value, in position D (forward) for the replacement gear each one gear up GE; From the highest gear is switched according to the invention in the next lower gear. When a clutch error in the position R (reverse) is in only one intended reverse gear no replacement gear possible, so that no adhesion is ensured in this gear.

If the counter a switching element exceeds the limit, then according to the following Table in the final Emergency switched.

Out The table shows that in the nearest higher gear is switched, which does not need the faulty switching element. If this is the next one higher Gang, then this is done directly via a normal upshift. Such a situation results, for example, in a defective Brake D.

Lie one or more courses in between, as for example in case of malfunction of the switching element A is the case in the first, second or third gear, then according to the invention a gear interpretation is carried out, wherein after a time in which the emptying of the switched in the last gear Ensures switching elements is, the emergency gear is engaged.

is an insert of a higher one Ganges not possible as for example for a defective clutch E is the case, then will be a Gangauslegen carried out and as long as electrically neutral, until the insertion of a lower emergency without reaching impermissibly high speeds is possible.

If several directly above each other lying corridors as final Emergency possible are, as for example for the brake D (gears 2-6) or the clutch E (gears 1-3) the Case is, so can this according to the present driver's request for this Gears still allows become.

For the reverse no emergency is possible if a limit for a participating switching element is achieved and, as in the described Wheelset and clutch combination, only one reverse gear is provided. If provided several reverse gears and the wheelset and clutch combination make this possible, then, according to the invention here also the gear monitoring invention carried out will be switched and if necessary an emergency.

1

converter

2

TCC

nx

Counter for the switching element x

A

switching element

B

switching element

C

switching element

D

switching element

e

switching element

Claims (5)

Method for gear monitoring for an automatic transmission of a motor vehicle, in which the individual gears are realized by the combination of two or more switching elements (A, B, C, D, E), characterized in that each switching element (A, B, C, D , E) is associated with a symptom counter (Nx) whose value is incremented by one upon the occurrence of a malfunction in a gear in which the switching element is involved, wherein, when a predetermined limit value for the symptom counter (Nx) is reached, this switching element or the corresponding switching system clearly identified as defective and the transmission is switched to a final emergency and wherein, if the predetermined limit value for the symptom counter (Nx) is not reached, is switched to a replacement gear, wherein only the gears are switched on which the clearly recognized as defective switching element or the corresponding switching system is not involved. Method according to claim 1, characterized in that that for all gears except the highest gear the replacement gear is the next higher gear is and that for the highest Gang the replacement gear the next lower gear is. Method according to claim 1 or 2, characterized that the final one Emergency gear the next higher gear is which does not need the faulty switching element, wherein when inserting a higher one Ganges not possible is carried out a gear laying and as long as neutral is driven until the insertion of a lower Emergency without reaching inadmissible high speeds possible is. Method according to claim 3, characterized that if between the current gear and the emergency gear one or several courses intervening, a gear layout is performed, the emergency gear after a period when the emptying of the last gear switched Ensures switching elements is, is inserted. Method according to one of the preceding claims, characterized marked that for the reverse gear an emergency reverse gear is switched if this is the Radsatz- and Schattelementkombination allows.