DE102017117829A1 - Method for testing a short circuit of an electric motor driving a hydraulic clutch actuator - Google Patents

Abstract

The invention relates to a method for testing a short circuit of a hydraulic clutch actuator controlling electric motor, in which a current of the electric motor (4) is measured. In a method in which even short circuits can be detected reliably, which have only a small current, the current in at least one of the phases (U, V, W) of the electric motor (4) is detected and evaluated by a short circuit diagnosis, which during a snooping operation of the hydraulic clutch actuator (4, 5, 7) is performed.

Description

The invention relates to a method for testing a short circuit of a hydraulic clutch actuator driving electric motor, in which a current of the electric motor is measured.

From the DE 10 2014 215 263 A1 a method for maintaining a safe driving condition of a motor vehicle by an actuator is known in which, for example, a clutch actuator has an electric motor which is controlled by a control unit. The controller includes a microcontroller for processing a software program for controlling the electric motor, which is connected via a driver stage with a power semiconductor having power amplifier, wherein the power semiconductors are connected via three phases with the electric motor.

It is known to perform a short circuit diagnosis of the electric motor during operation, but which has a very high threshold, so that all possible currents that can occur in the electrically commutated electric motor, can be covered. This has the disadvantage that short circuits, which have only a smaller current size, can not be detected.

The invention has for its object to provide a method for testing a short circuit of a hydraulic clutch actuator driving electric motor, in which short circuits of different sizes of the current can be reliably detected.

According to the invention the object is achieved in that the current is detected in at least one of the phases of the electric motor and evaluated by a short circuit diagnosis, which is performed during a sniffing operation of the hydraulic clutch actuator. Since the clutch actuator is in a no-load position during the snooping process, in which the electric motor is not operated, thus even the smallest currents that flow as a short-circuit current in the electrical wiring of the clutch actuator can reliably detect.

Advantageously, during the short-circuit diagnosis, the current measured in the phase is compared with a short-circuit threshold which is lower than a system short-circuit threshold to be used for determining the short circuit during normal operation of the electric motor, and if the short-circuit threshold is exceeded, a short-circuit is detected by the measured current. Since all signals that are associated with the commutation of the electric motor during standstill of the electric motor, even a small short-circuit current can be reliably determined, since disturbances are suppressed.

In one embodiment, after the start of the sniffing operation by taking a snooping position by a master cylinder of the hydraulic clutch actuator, the short circuit diagnosis is started, set the short-circuit threshold from the Systemkurzschlussschwellwert and measured the current in the at least one phase of the electric motor, wherein when exceeding the short-circuit threshold on a short between the electric motor and a Motoransteuerschaltung comprehensive housing of a control unit is closed. With this very simple method, a short-circuit situation is reliably detected even with small short-circuit currents.

In a further development, after the short circuit diagnosis has been completed, the short-circuit threshold value is reset to the system short-circuit threshold value by triggering a value which is above the system short-circuit threshold, from which the system short-circuit threshold is lowered. This jump to an inflated value speeds up the leveling of the system shorting threshold.

In one variant, the short-circuit threshold value is predetermined by a microcontroller, which is connected via a low-pass filter to the motor drive circuit of the electric motor, wherein a settling time of the low-pass filter for setting the short-circuit threshold is less than a duration of the snoop operation. Since the low-pass filter always requires a predetermined period of time to set a new threshold, the execution of the adjustment of the short-circuit threshold during the sniffing operation of the clutch actuator is particularly advantageous because the setting of the threshold values, the movement of the clutch actuator is not affected.

The invention allows numerous embodiments. One of them will be explained in more detail with reference to the figures shown in the drawing.

• 1 eine Prinzipdarstellung eines hydrostatischen Kupplungsbetätigungssystems mit einer hydrostatischen Übertragungsstrecke,
• 2 eine Prinzipdarstellung einer Ansteuerung eines elektrisch kommutierten Elektromotors eines Kupplungsaktors.

Show it:

• 1 a schematic diagram of a hydrostatic clutch actuation system with a hydrostatic transmission path,
• 2 a schematic diagram of a control of an electrically commutated electric motor of a clutch actuator.

In 1 is an embodiment of a structure of a hydrostatic clutch actuation system 1 for use in a motor vehicle. The hydrostatic clutch actuation system 1 includes on the donor side 2 a clutch control unit 3 that has an electric motor 4 via a gearbox 5 with a piston 6 a master cylinder 7 kinematically connected. When the position of the clutch actuator changes 1 and thus the piston 6 in the master cylinder 7 along the Aktorweges to the right is a volume of the master cylinder 7 changed, creating a pressure p in the master cylinder 7 is built, which has a pressure medium 8th via a hydraulic line 9 to the recipient side 10 is transmitted. On the taker side 10 causes the pressure p of the pressure medium 8th in a slave cylinder 11 a change of direction acting on the clutch 12 is transmitted to operate this.

The master cylinder 7 is with a surge tank 13 connected, wherein a connection opening 14 of the master cylinder 7 through the piston 6 of the master cylinder 7 is released when the piston 6 is in a predetermined position. The piston 6 reaches this position by moving further from the position shown to the left. In this position is the pressure medium 8th usually unconfirmed and the pressure p in the master cylinder 7 minimal. By releasing a pressure and / or volume and / or temperature compensation of the pressure medium 8th allows. This process is also referred to as sniffing and the position of the piston 6 in which the connection opening 14 is released is called a snoop position.

In 2 is an embodiment of the clutch control unit 3 shown. The clutch control unit 3 includes a microcontroller 15 which has a low pass filter 16 with a motor drive circuit 17 connected is. The motor drive circuit 17 is over three phases U, V, W with the electric motor 4 coupled. In the microcontroller 15 are a system short-circuit threshold for the operation of the electrically commutated electric motor 4 as well as a short-circuit threshold for determining a short circuit between a housing 18 of the clutch control unit 3 and the electric motor 4 specified. The short-circuit threshold is smaller than the system short-circuit threshold.

After the piston 6 the master cylinder 7 has been moved to its sniffer position is due to the electric motor 4 No load, so that a short circuit diagnosis can be activated, by means of which it is detected, whether a short circuit between the housing 18 of the clutch control unit 3 and the electric motor 4 is present. During the short circuit diagnosis, the short-circuit threshold value goes to the low-pass filter 16 output, which settles and sets the appropriate passage conditions. The settling time of the low-pass filter 16 must be less than the duration of the sniffing process, so that the short circuit diagnosis can take place in a state in which the electric motor 4 is not active.

After the low pass filter 16 is settled, is a measurement of the motor current at least one of the phases U . V . W of the electric motor 4 started. The at least one phase U . V . W measured current is compared with the short-circuit threshold. If the short-circuit threshold is exceeded by the on the phases U . V . W measured current is due to a short circuit between the housing 18 of the clutch control unit 3 and the electric motor 4 recognized. When the short circuit diagnosis is finished, the short-circuit threshold on the low-pass filter becomes 16 replaced again by the system shorting threshold. This is done so that the low-pass filter 16 first a value is created which is higher than the system short-circuit threshold. Subsequently, this higher value is used to reduce back to the system short-circuit threshold. This variant offers a fast adjustment of the low-pass filter 16 to the system shortcut threshold.

Due to the described solution, a short circuit also occurs at high impedance of the phases U . V . W of the electric motor 4 reliably detected.

LIST OF REFERENCE NUMBERS

1

Clutch actuation system

2

donor side

3

Clutch control unit

4

electric motor

5

transmission

6

piston

7

Master cylinder

8th

lever

9

hydraulic line

10

recipient side

11

slave cylinder

12

clutch

13

surge tank

14

connecting opening

15

microcontroller

16

Low Pass Filter

17

motor drive circuit

18

Housing of the clutch control unit

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely 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.

Cited patent literature

• DE 102014215263 A1 [0002]

Claims (5)

Method for testing a short circuit of a hydraulic clutch actuator controlling electric motor, in which a current of the electric motor (4) is measured, characterized in that the current in at least one of the phases (U, V, W) of the electric motor (4) detected and from a short circuit diagnosis is performed, which during a Schnüffelvorganges of the hydraulic clutch actuator (4, 5, 7) is executed. Method according to Claim 1 , characterized in that during the short circuit diagnosis of the current measured in the phase is compared with a Kurzschlussschwellwert, which is lower than a short-circuit determination during normal operation of the electric motor (4) approaching System Kurzschlussschwellwert, wherein when exceeding the short-circuit threshold by the measured current to a short circuit is recognized. Method according to Claim 1 or 2 , characterized in that after the start of the sniffing operation by taking a snooping position by a master cylinder (7) of the hydraulic clutch actuator (4, 5, 7), the short circuit diagnosis is started, the short-circuit threshold adjusted from the Systemkurzschlussschwellwert and the current in the at least one phase (U , V, W) of the electric motor (4) is measured, wherein when the short-circuit threshold is exceeded, a short circuit between the electric motor (4) and a housing (18) of a motor drive circuit (17) comprising control unit (3) is concluded. Method according to Claim 1 . 2 or 3 characterized in that upon completion of the short circuit diagnosis, the short circuit threshold is reset to the system shorting threshold by driving a value which is above the system shorting threshold from which the system shorting threshold is lowered. Method according to at least one of the preceding claims, characterized in that the short-circuit threshold is predetermined by a microcontroller (15) which is connected via a low-pass filter (16) to the motor drive circuit (17) of the electric motor (4), wherein a settling time of the low-pass filter ( 16) for setting the short-circuit threshold is smaller than a period of the snooping operation.

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