Fault detection for a torque converter

Abstract

A monitoring device and a method for operating an idling automatic transmission of a motor vehicle having a torque converter which includes at least one pump wheel and a turbine wheel that are designed to transmit torque hydrodynamically from one to the other. The method includes at least the following steps of: determining a rotational speed of the turbine wheel; determining a load on the motor of the motor vehicle; and recognizing whether there is a blockage in the drive-train of the motor vehicle or whether the torque converter is running dry, as a function of the turbine rotational speed and the motor load detected.

Claims

1. A method of operating an idling automatic transmission of a motor vehicle which has a monitoring device and a torque converter, wherein the torque converter comprises at least one pump wheel and a turbine wheel which are designed to transmit torque hydrodynamically from one to the other, the method comprises at least the following steps: determining, with the monitoring device, a rotation speed of the turbine wheel; determining, with the monitoring device, a load on a motor of the motor vehicle; and recognizing, with the monitoring device, whether there is a blockage in a drive-train of the motor vehicle or whether the torque converter is running dry, as a function of the turbine rotation speed and the motor load determined; and emitting a signal with the monitoring device to control a transmission of torque via at least one of the torque converter and the automatic transmission based on a recognition of the blockage in the drive-train, a recognition that the torque converter is running dry and a recognition of a normal condition of the drive-train.

2. The method according to claim 1, further comprising recognizing, as the function of the turbine rotation speed and the motor load, whether the drive-train is in the normal condition; and when the normal condition of the drive-train is recognized by the monitoring device, functionally connecting the pump wheel and the turbine wheel to transmit torque via the torque converter, and actuating a transmission shifting element to engage a gear in the automatic transmission and transmit torque via the automatic transmission to permit starting off of the motor vehicle.

3. The method according to claim 1, further comprising recognizing, with the monitoring device, the blockage in the drive-train of the motor vehicle or the torque converter is running dry only when the rotation speed of the turbine wheel is equal to or lower than a predetermined threshold value.

4. The method according to claim 1, further comprising recognizing, with the monitoring device, the blockage in the drive-train of the motor vehicle or the torque converter is running dry only when the motor vehicle is at rest.

5. The method according to claim 1, further comprising recognizing, with the monitoring device, that the torque converter is running dry when the load on the motor is below a threshold value.

6. The method according to claim 1, further comprising, when it is recognized that the torque converter is running dry, producing a no fault signal with the monitoring device.

7. The method according to claim 1, further comprising, when it is recognized that the torque converter is running dry, producing a wait signal with the monitoring device and preventing a gear engagement in the automatic transmission until the torque converter is filled with a liquid transfer medium.

8. The method according to claim 7, further comprising, when it is recognized that the torque converter is running dry, allowing the gear engagement in the automatic transmission as a function of a subsequently determined rotation speed of the turbine wheel.

9. The method according to claim 1, further comprising, when the blockage in the drive-train is detected by the monitoring device, producing with the monitoring device a fault signal to control transmission of torque via at least one of the torque converter and the automatic transmission.

10. The method according to claim 1, further comprising providing the torque converter with an open liquid reservoir.

11. A monitoring device for an automatic transmission of a motor vehicle having a torque converter, wherein the torque converter comprises at least one pump wheel and a turbine wheel which are designed to transmit torque hydrodynamically from one to the other, and the transmission has a drive input, a drive output and at least one shifting element which is actuatable to engage and disengage the drive input and the drive output, wherein the monitoring device is designed, when the automatic transmission is idling, to: determine a rotation speed of the turbine wheel; determine a load on the motor of the motor vehicle; and as a function of the turbine rotation speed and the motor load determined, to recognize a blockage in a drive-train of the motor vehicle or the torque converter is running dry; the monitoring device is designed to emit a signal when the blockage in the drive-train is recognized, and emit another signal when the torque converter is running dry is recognized; the pump wheel and the turbine wheel are functionally connectable and disconnectable to control torque transmission therebetween, and the at least one shifting element is actuatable to engage and disengage the drive input and the drive output of the automatic transmission, based on the signal emitted by the monitoring device.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) FIG. 1 is a schematic view illustrating a method for operating an automatic transmission of a motor vehicle, which method is implemented at least partially by a monitoring device of the transmission.

DETAILED DESCRIPTION OF THE INVENTION

(2) FIG. 1 is a schematic view illustrating a monitoring device 10 for an automatic transmission of a motor vehicle. The automatic transmission comprises a torque converter. The torque converter comprises at least one pump wheel and a turbine wheel. The pump wheel and the turbine wheel are designed to transmit torque hydrodynamically from one to the other. The monitoring device 10 is designed, when the automatic transmission is idling, to determine, as a first step 12 of a method for operating the automatic transmission, the rotation speed of the turbine wheel. In the illustrated example, this determination is carried out by a sensor connected to the monitoring device 10. The monitoring device 10 is designed, when the automatic transmission is idling, to determine, as a step 14 of the said method, a load on the motor of the motor vehicle. For this, in the illustrated example, the value is communicated to the monitoring device 10 by way of a CAN bus of the motor vehicle. In a further step 16 of the method, as a function of the rotation speed of the turbine and the load on the motor detected, the monitoring device 10 recognizes whether there is a blockage in the drive-train of the motor vehicle or whether the torque converter is running dry, or whether the drive-train of the motor vehicle is in a normal condition. The method is carried out when the motor vehicle has first been started up from a standstill but has not yet moved off.

(3) In the illustrated example, a blockage is recognized if the turbine rotation speed detected is zero and the motor load is elevated compared with an expected threshold value which, for example, is stored as a function of other consumers or is a fixed value. In such a case, a fault signal 18 is emitted, which indicates the blocking of other control units. The control units can then control the automatic transmission or the motor vehicle as a function of the said fault signal 18. In the illustrated example, a dry-running torque converter is recognized if the rotation speed of the turbine is zero and the load on the motor is equal to or less than the expected threshold value. In such a case a signal 20 is emitted, which indicates that the torque converter is running dry. In other embodiments, it is also possible for no signal to be emitted or for a signal to be emitted which indicates that the automatic transmission is in the normal condition. In the illustrated example, the normal condition is recognized when the turbine rotation speed is above zero. In such a case, a signal 22 is emitted, which indicates that the automatic transmission is in a normal condition. In other embodiments, it is also possible for no signal to be emitted for the normal condition. The respective signals 18, 20, 22 can be emitted by the monitoring device 10 to the CAN bus.

INDEXES

(4) 10 Monitoring device 12 Determination of a rotation speed of the turbine wheel 14 Determination of a load on the motor 16 Recognition whether there is a blockage or whether the torque converter is running dry 18 Fault signal due to a blockage 20 Signal that the torque converter is running dry 22 Signal indicating a normal condition