DE10237245A1 - Gear monitoring process for an automatic drive in a motor vehicle, using combination of switch elements with a symptom counter for each element - Google Patents

Abstract

A gear monitoring process in an automatic motor vehicle drive combines two or more switch elements (A-E) for each gear and comprises a symptom counter (Nx) for each element whose value is incremented through an error function. The gear is switched to a final emergency gear in case of a defect and to a substitute gear if a threshold is not reached.

Description

The present invention relates to a procedure for 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, the DE 196 01 618 A1 proposed by the applicant to detect malfunctions outside of the circuits by monitoring the measured transmission input and output speeds. Then the current gear is switched to a replacement gear, which is the next highest if possible; if the current gear is the highest, then the next lower gear is selected. As part of the DE 196 01 618 A1 a symptom counter is provided for each gear, which is incremented by one if a palling function is present, an emergency driving program being activated when a predetermined limit value for the symptom counter is exceeded.

This procedure according to the state The technology results in gear systems in which a clutch or brake in multiple gears is connected in series, in the event of a malfunction in one of these Switching elements or switching systems in several circuits and one subsequent Detection of malfunctions, before a safe operating state is reached. Here is below Switching system the entire chain from control to one Understanding switching element so that it is a malfunction e.g. an incorrect specification of the control, an incorrect one Current pressure conversion to a malfunction in the valve system or also a malfunction of a component of a switching element or an oil leak can act. The same also applies to gear systems with always recurrent activation of the same switching element in the next gear, in which case for a safe state is reached for a short time; however, from the system at the next Up or down shift tried again a switching element with no longer available function to bring into the flow of power.

The present invention lies therefore based on the task, based on the state of the art Technique a procedure for gait monitoring for a Automatic transmission of a motor vehicle specify the disadvantages avoids the prior art. The method according to the invention should also for Gearboxes with multiple use of clutches and brakes and their Control can be used.

In particular, as part of the process a malfunction of a switching element can be detected and this Switching element can be assigned. In this way, multiple times occurring safety-critical conditions are largely avoided become; Moreover in this way the availability of the Vehicle increased.

It also aims to respond quickly guaranteed for a malfunction and the gearbox is effectively protected against damage or destruction.

This task is due to the characteristics of claim 1 solved. Further variants and advantages emerge from the subclaims.

Accordingly, it is suggested to everyone Assign shift element of the transmission a symptom counter Nx, the Value when a malfunction occurs in a hallway in which the Switching element is involved, being incremented by one, if a predetermined limit for the symptom counter Nx is reached, this switching element or the corresponding switching system clearly recognized as defective and the transmission in a final emergency gear is switched without the involvement of this switching element and, if the specified limit for the symptom counter Nx is not reached, is switched to an alternative gear.

The final emergency gear can, according to the invention, if the needed Switching possible is to be inserted directly or by inserting a safe one Condition by gear selection and opening the transmission and the subsequent Change to the replacement gear that cannot be switched directly by appropriate gear engagement can be realized.

If an emergency is necessary, of several courses is below the current gear in which the malfunction occurred is then the emergency room only becomes suitable after falling below it Speed thresholds for engaged this emergency gear to avoid the danger of impermissible speeds. As long as the speed thresholds are not fallen below, it is preferred in the "neutral" state connected.

The method according to the invention has the advantage on that in most transmissions immediately after a recurrence of a fault determines the defective switching element or switching system and a reaction is initiated. It is the fastest Possibility, to determine the defective switching element because of the involvement of two switching elements in each gear another occurrence of a Misconduct is necessary to clearly identify the defective switching element to determine.

By assigning the error to a Switching element or switching system enables a targeted reaction; this is an important difference from the prior art where the malfunction is assigned to the gear. The detection of a malfunction can be carried out in one course per se according to the prior art.

The invention is illustrated below based on the attached Figures closer explained. They represent:

1 : A representation of the most important steps of the method according to the invention using a flow chart;

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

3 : 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, everyone Switching element a counter assigned whose value - starting at zero - at any occurrence of a malfunction in a passage on which this Switching element involved is increased by one.

There exists for each switching element a limit for its counter, which is preferably based on the number of those involved in a course Shifting elements and the number of gears in which this shifting element is involved depends on is. In other words, the limit corresponds to the number of Gears with Malfunction that must be present in order to be able to clearly identify a defective switching element. If for example, a switching element is involved in two gears and for this Courses each two switching elements are activated, then the limit is two, because with it the defective switching element is clearly identifiable.

According to 1 , which represents the method in the event of a malfunction in a forward gear, is provided to increase the counters assigned to the shift elements involved by one when a malfunction occurs 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 into a final Emergency gear initiated, depending on the situation, first after "neutral" is switched to inadmissible to avoid high speeds or if one circuit over several Gears necessary is. Optionally, this can be entered in the diagnosis management.

If the limit for the counter is not exceeded then a shift to an alternative gear is carried out. 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 after the driver's request, the driver's request not the malfunction Corresponding gear and the driver request the next higher gear is then switched according to the driver's request.

If the above conditions are not met, then the replacement gear is maintained until a new driver request is generated; in this case it is checked again whether the Driver request does not correspond to the gear malfunctioning and the replacement gear the next higher gear is etc.

Then the query follows Driving position. If the position is N, P or R, then the normal function is entered, otherwise, as already explained, the replacement gear with the Compare driver request and run 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 are shown. The circuit diagram corresponding to this gearbox is the subject of 3 , The shift pattern shows that two shift elements are involved in each gear. Here, N1-N6 denote the gear tracking in "neutral". There, too, the gear is specified according to the gear to be engaged in the driving position.

With this gearbox, according to 4 , if the counter Nx is less than its limit value, shifts one gear up in position D (forward) for the spare gear; According to the invention, the highest gear is shifted to the next lower gear. In the event of a clutch fault in position R (reverse), only one intended reverse gear is not possible, so that no frictional engagement is guaranteed at this speed.

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

From the table it can be seen that the gear is shifted into the next higher gear which does not require the faulty shift element. If this is the next higher gear, then this is done directly via a normal upshift. Such a situation arises, for example, at ei a defective brake D.

If there are one or more courses in between, such as in the event of a malfunction of the switching element A is the case in the first, second or third gear, then according to the invention gear selection is carried out, wherein after a time when the emptying shifted in the last gear Guaranteed switching elements the emergency gear is engaged.

Is an engagement of a higher gear not possible, like for example for a defective clutch E is the case, then a gear will disengage carried out and controlled electrically neutral until the insertion of a lower emergency gear is possible without reaching impermissibly high speeds.

If several directly one above the other lying gears as the final Emergency emergency possible are like this for example the brake D (gears 2–6) or the clutch E (gears 1– 3) the case is so can this if the driver wishes to do so Gears still allows become.

For the reverse gear an emergency room is not possible, if a limit for a switching element involved is reached and, as in the described Wheelset and clutch combination, only one reverse gear is provided. If several reverse gears provided and the wheelset and clutch combination make this possible, then, according to the invention, the gait monitoring according to the invention can also be used here carried out and if necessary an emergency gear can be switched.

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 (6)

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 shift elements (A, B, C, D, E), characterized in that each shift element (A, B, C, D , E) a symptom counter (Nx) is assigned, the value of which is incremented by one when a malfunction occurs in a gear in which the switching element is involved, and when a predetermined limit value for the symptom counter (Nx) is reached, this switching element or the corresponding switching system is clearly identified as defective and the transmission is switched to a final emergency gear and, if the predetermined limit value for the symptom counter (Nx) has not been reached, the gear is switched to an alternative gear. A method according to claim 1, characterized in that for all gears Exception of the highest gear the replacement gear the next higher gear is and that for the highest Gear the replacement gear the next is lower gear. A method according to claim 1 or 2, characterized in that the final Emergency gear the next higher gear which does not need the faulty switching element, when inserting a higher one Ganges not possible is carried out gear selection and until neutral is activated until a lower one is inserted Emergency not allowed without reaching high speeds possible is. A method according to claim 3, characterized in that when there are one or more gears between the current gear and the emergency gear, gear shifting performed is, the emergency room after a time in which the emptying of the Switching elements in the last gear is guaranteed. Method according to one of the preceding claims, characterized in that that for the reverse gear an emergency reverse gear is switched if this is the wheelset and shift element combination allows. Method according to one of the preceding claims, characterized in that only the gears are shifted at which the shift element clearly identified as defective or the corresponding shift system is not involved.