DE102018130764A1 - Method for reducing the power consumption of a parking lock actuator - Google Patents

Abstract

The invention relates to a method for reducing the power consumption of a parking lock actuator, which is supplied with current by power electronics which are controlled by a microcontroller, the power electronics and the microcontroller forming a power unit. In a method in which the power consumption of the parking lock actuator is reduced, the parking lock actuator is put into a low-power mode, from which it is retrieved depending on a vehicle speed.

Description

The invention relates to a method for reducing the power consumption of a parking lock actuator, which is supplied with current by power electronics which are controlled by a microcontroller, the power electronics and the microcontroller forming a power unit.

Vehicles usually have a parking lock, which has a parking pawl and a parking lock wheel. By engaging the parking lock in a tooth gap of the parking lock wheel, a positive connection between the drive train of the vehicle and the transmission housing is produced. The vehicle is thus secured. By removing the parking pawl from the tooth gap, the drive train of the vehicle and thus the vehicle are unlocked. Such a parking lock is exemplary from the DE 102 59 893 A1 known.

In addition, it is known that the parking lock actuator has a power management integrated unit in which a power unit and a microcontroller are integrated. The silicon temperature of the microcontroller and the power unit exceeds a permissible upper limit at maximum ambient temperatures solely due to the power unit's power loss without motor movement. This heating is derived via a thermal connection of the electronics to a metal housing.

In certain cases, the self-heating of the power unit and the microcontroller can exceed the respective junction temperature of the components due to a high current consumption in the operating mode of the parking lock actuator.

The invention has for its object to provide a method for reducing the power consumption of a parking lock actuator, in which the current consumption is reduced and thus the self-heating of the power unit and the microcontroller is reduced.

According to the invention, the object is achieved in that the parking lock actuator is put into a low-power mode, from which it is retrieved as a function of a vehicle speed. This has the advantage that the parking lock actuator is only actuated at the beginning and at the end of the journey of the vehicle. The parking pawl must not engage while the vehicle is moving, which is why the parking lock actuator is not activated. The fact that the parking lock actuator is put into a low-power mode as a function of the vehicle speed significantly reduces the power loss of the critical components, such as the microcontroller and power unit, which is why the component temperature limits can be maintained.

A wake-up timer is advantageously set as a function of the vehicle speed. This is done by the microcontroller, which measures the vehicle speed and thus specifies the period for the low-power mode.

In one embodiment, the microcontroller is put into a sleep mode, from which it is retrieved after the wake-up timer has expired. During sleep mode, it is assumed that the vehicle is in motion and therefore no activation of the parking lock actuator is necessary. The microcontroller is only automatically woken up by the wake-up timer if the vehicle speed indicates that the vehicle is about to come to a standstill.

In one variant, the microcontroller remains active below a predetermined vehicle speed. This ensures that the microprocessor can always operate the parking lock actuator when the vehicle is about to come to a standstill.

The invention permits numerous embodiments. One of these will be explained in more detail with reference to the figure shown in the drawing.

• 1 ein Ausführungsbeispiel des erfindungsgemäßen Verfahrens.

It shows:

• 1 an embodiment of the method according to the invention.

In 1 An embodiment of the method according to the invention is shown, which in block 100 is started. In the block 110 a microcontroller of a power management unit controlling the parking lock is put into normal operation. Then in the block 120 checked whether the vehicle is in motion. If this is not the case, it becomes a block 110 declined. Will be in the block 120 determined that the vehicle is moving, it is checked whether the vehicle speed v greater than a predetermined threshold S is (block 130 ). If this is not the case, it becomes a block 110 declined. Exceeds the vehicle speed v the threshold S in the block 130 , so in the block 140 a wake-up timer depending on the vehicle speed v set. The faster the vehicle travels, the longer the time-out may take t _WAKE , which is specified by the wake-up timer. Then in the block 150 the microcontroller is put into sleep mode, since it was determined on the basis of the measurement of the vehicle speed that the vehicle is in motion and actuation of the parking lock actuator is not necessary. After the wake-up timer has expired, the microcontroller is automatically woken up and is active again around its periphery or the to analyze messages on a CAN bus, including the vehicle speed. Depending on the current vehicle speed, the process described begins again.

The microcontroller remains active below a minimum speed of the vehicle. It is also possible to wake up the microcontroller via the CAN bus using a receive interrupt, which can be done depending on the system architecture.

wobei s den Anhalteweg bei einer Vollbremsung des Fahrzeuges und v die aktuelle Fahrzeuggeschwindigkeit darstellt.With the proposed method, the time-out t _WAKE of the wake-up timer is calculated using the following formula: $${\text{t}}_{\text{WAKE}}=\mathrm{2nd}*\text{s}/\text{v},$$

where s is the stopping distance when the vehicle brakes fully and v represents the current vehicle speed.

In an exemplary calculation of the stopping time s of the vehicle, approximately 8.3 m / s are covered at the average speed of 30 km / h. This results in a stopping distance s at full braking of 9 m. The stopping time is 2.16 s. The resulting active / pause ratio is 1:20, which means that the microcontroller only has to be active for about 5% of the total time, which greatly reduces the power consumption of the parking lock actuator.

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 10259893 A1 [0002]

Claims (4)

Method for reducing the power consumption of a parking lock actuator, which is supplied with current by power electronics which are controlled by a microcontroller, the power electronics and the microcontroller forming a power unit, characterized in that the parking lock actuator is switched to a low-power mode, from which it is retrieved depending on a vehicle speed. Procedure according to Claim 1 , characterized in that a wake-up timer is set depending on the vehicle speed. Procedure according to Claim 1 or 2nd , characterized in that the microcontroller is put into a sleep mode, from which it is retrieved after the wake-up timer has expired. Procedure according to Claim 1 , 2nd or 3rd , characterized in that the microcontroller remains active below a predetermined vehicle speed.

Images