Electromechanical switching unit for a motor vehicle and method for determining a switching position of at least one electromechanical switch of such an electromechanical switching unit

Abstract

An electromechanical switching unit (1) for a motor vehicle comprising at least one electromechanical switch (2) and an actuator unit for switching the at least one electromechanical switch into at least two switching positions, namely a closed switching position and an open switching position, wherein the actuator unit comprises an electric motor (3) rotatable in two directions of rotation, namely in a first direction of rotation and in a second direction of rotation opposite to the first direction of rotation, a stepping gear (4) and a switching shaft (5), wherein the electric motor (3) is connected to the switching shaft (5) via the stepping gear (4) in a position-effective manner and the switching shaft (5) is connected to the at least one electromechanical switch (2) in a position-effective manner, as well as a method for determining the position of the switching shaft (5) and thus a switching position of the at least one electromechanical switch (2) of such an electromechanical switching unit (1).

Description

[0001] The invention relates to an electromechanical switching unit for a motor vehicle, in particular a hybrid or electric motor vehicle, comprising at least one electromechanical switch and an actuator unit for switching the at least one electromechanical switch in at least two switching positions, namely a closed switching position or an open switching position, wherein the actuator unit comprises an electric motor rotatable in two directions of rotation, namely in a first direction of rotation and in a second direction of rotation opposite to the first direction of rotation, a stepping gear and a switching shaft.

[0002] The invention further relates to a method for determining the position of a switching shaft and thus for determining a switching position of at least one electromechanical switch of such an electromechanical switching unit when the motor vehicle is stationary and / or in the event of a fault in a motor vehicle. State of the art

[0003] Electromechanical switching devices, which use an electric motor to determine the position and control switching shafts, are widely used in modern motor vehicles. These systems are fully functional under normal operating conditions and ensure precise control of the switching positions. However, malfunctions in the processing units of control units or voltage drops in the vehicle's electrical system can lead to a loss of important position data. In such cases, a "reset event" is typically triggered via a safety mechanism, restarting a software sequence on the control unit's processing units at a defined and safe point. This often results in the loss of values ​​for variables stored in volatile memory, such as the current position of a switching shaft in an electromechanical switching unit.

[0004] Due to the gear ratio between an electric motor and a shifting system, absolute referencing of a shift shaft's position via a position signal from the electric motor is no longer possible. A technical solution to this problem would be to use an additional absolute position sensor on a gearbox output, but this would incur additional costs.

[0005] The precise position of a switching shaft is fundamental to the control and safety of the system. Deviations in positioning inevitably lead to operational risks in an electromechanical switching unit. For example, insufficient contact pressure of electromechanical switches can result in high contact resistance. In extreme cases, a persistent gap between the contacts can cause an arc, leading to contact burn-off.

[0006] One object of the invention is to provide an improved electromechanical switching unit suitable for use in a motor vehicle.

[0007] Secondly, the invention aims to provide a simple and economically optimized method for determining the position of a switching shaft of the electromechanical switching unit. Description of the invention

[0008] The problem is solved by an electromechanical switching unit with the features according to claim 1 and further by a method for determining the position of a switching shaft and thus a switching position of at least one electromechanical switch of an electromechanical switching unit according to claim 5.

[0009] The electromechanical switching unit according to the invention for a motor vehicle comprises at least one electromechanical switch and an actuator unit for switching the at least one electromechanical switch in at least two switching positions, namely a closed switching position and an open switching position.

[0010] According to the invention, the actuator unit comprises an electric motor rotatable in two directions of rotation, namely in a first direction of rotation and in a second direction of rotation opposite to the first direction of rotation, a stepping gear and a switching shaft.

[0011] According to the present invention, the electric motor is connected to the switching shaft via the stepping gear in an adjustment-effective manner, and the switching shaft is connected to the at least one electromechanical switch in an adjustment-effective manner.

[0012] According to the invention, the stepping mechanism comprises a drive wheel with a pin effectively connected to the electric motor and a stepping gear wheel with at least two grooves effectively connected to the switching shaft, wherein the stepping mechanism is designed such that when the drive wheel rotates, the pin periodically engages in the grooves of the stepping gear wheel, thus causing an intermittent rotational movement of the stepping gear wheel and thus of the switching shaft.

[0013] Furthermore, according to the invention, at least one groove of the stepping gear wheel is designed to be closed, so that the pin of the drive wheel cannot engage in this groove and thus at least one end stop is created in each direction of rotation of the electric motor.

[0014] In an advantageous embodiment of the present invention, the stepping gear wheel has four grooves distributed evenly around its circumference, wherein one of the four grooves is closed and the other three of the four grooves are not closed.

[0015] The switching shaft preferably has at least one switching cam which is connected to the electromechanical switch in an adjustment-effective manner.

[0016] Particularly preferably, the switching shaft has a number of switching cams corresponding to the number of electromechanical switches of the electromechanical switching unit, wherein each switching cam is assigned to an electromechanical switch in an adjustment-effective manner.

[0017] The method according to the invention serves to determine the position of a switching shaft and thus to determine a switching position of at least one electromechanical switch of an electromechanical switching unit according to the invention when the motor vehicle is stationary and / or in the event of a fault in a motor vehicle and comprises the following steps: - Approaching the end stop in the first direction of rotation of the electric motor, - Detecting the reaching of the end stop in the first direction of rotation of the electric motor by detecting an increase in the current consumption of the electric motor and detecting a rotational speed of an output shaft of the electric motor that is equal to zero, - Activating an incremental counter to count the increments detected during the following movement of the electric motor, - Approaching the end stop in the second direction of rotation of the electric motor, - Detecting the reaching of the end stop in the second direction of rotation of the electric motor by detecting an increase in the current consumption of the electric motor and detecting a speed of the output shaft of the electric motor that is equal to zero, - Deactivating the incremental counter and recording the counted increments of the incremental counter, and - Comparing the number of increments counted by the incremental counter with the number of increments intended by the electric motor, whereby if the number of increments counted and the number of increments intended by the electric motor match, the desired switching position is engaged and the position of the switching shaft is stored in a non-volatile memory, and if the number of increments counted and the number of increments intended by the electric motor do not match, an error condition is output.

[0018] By means of the design of the electromechanical switching unit according to the invention, a precise and reliable method for controlling an electromechanical switch of the electromechanical switching unit can be easily implemented. Description of the characters

[0019] The underlying concept of the invention will be explained in more detail below with reference to the embodiment shown in the figures. These show: Fig. 1 A schematic sectional view of an electromechanical switching unit. Fig. 2a a schematic view of a stepping mechanism, wherein the drive wheel is rotated in a first direction of rotation. Fig. 2b a schematic view of a stepping mechanism, wherein the drive wheel is rotated in a second direction of rotation. Fig. 3 schematically illustrates the process flow of a procedure for determining the position of a switching shaft.

[0020] An electromechanical switching unit 1 for a motor vehicle, in particular for a hybrid or electric motor vehicle, comprises at least one electromechanical switch 2 and an actuator unit for switching the electromechanical switch 2 into two switching positions, namely a closed switching position and an open switching position.

[0021] The actuator unit comprises an electric motor 3, a stepping gear 4, and a switching shaft 5. The electric motor 3 is connected to the switching shaft 5 via the stepping gear 4, and the switching shaft 5 is connected to the at least one electromechanical switch 2, also with respect to adjustment.

[0022] The electric motor 3 is designed to rotate in two directions: a first direction and a second direction opposite to the first. The electric motor 3 thus provides the driving force in the electromechanical switching unit 1. It rotates continuously in its respective direction and supplies the necessary energy to operate the stepper motor 4.

[0023] The stepping mechanism 4 has a drive wheel 6 with a pin 7 and a stepping gear wheel 8, wherein the drive wheel 6 is effectively connected to an output shaft 11 of the electric motor 3 and the stepping gear wheel 8 is effectively connected to the switching shaft 5. The drive wheel 6 rotates continuously in accordance with the continuous rotary motion of the electric motor 3.

[0024] The stepping gear wheel 8 has four grooves 9a, 9b evenly spaced around its circumference, one groove 9a of the four grooves 9a, 9b being closed and three grooves 9b of the four grooves 9a, 9b being open.

[0025] The indexing mechanism 4 is designed such that when the electric motor 3 and thus the drive wheel 6 rotates, the pin 7 of the drive wheel 6 periodically engages in the open, i.e., unclosed, grooves 9b of the indexing gear 8, thereby generating an intermittent rotary motion of the indexing gear 8 and thus of the switching shaft 5. The switching shaft 5 thus moves in discrete steps, corresponding to the motion of the indexing gear 8.

[0026] The pin 7 of the drive wheel 6 cannot engage in the closed groove 9a of the stepping gear wheel 8, and the stepping gear wheel 8 is not rotated further. The closed groove 9a thus forms an end stop in both the first and second directions of rotation of the electric motor 3.

[0027] If a groove 9a of the indexing gear 8 is blocked, the pin 7 of the drive gear 6 cannot engage in this groove 9a. This prevents the indexing gear 8 from rotating further when the pin 7 reaches the position of the blocked groove 9a. The movement of the indexing gear 8 is blocked, and it remains in its current position. Thus, if a groove 9a is blocked, the intermittent movement is interrupted. The indexing gear 8 does not rotate further through the intended angle, and the shift shaft 5 also remains in its current position.

[0028] In Fig. Figure 3 schematically illustrates a procedure for determining the position of the switching shaft 5. Fig. 3 uses the symbol “-” for “no” and the symbol “+” for “yes”.

[0029] An unclear position of switching shaft 5 (S) triggers the process.

[0030] At the start of the process, the vehicle's operating status is checked in a first query block A, specifically whether the vehicle is moving (+) or not (-). A positive answer (+) results in a loop back to the first query block A. A negative answer (-) triggers a second query block B, which checks whether the vehicle is in charging mode. A negative answer (-) to the second query block B leads to a second function block D, in which the electric motor 3, and thus the drive wheel 6 of the stepper motor 4, is activated in the first direction of rotation. A positive answer (+) to the second query block B leads to a first function block C, in which the vehicle's charging process is terminated. Only after the vehicle's charging process has finished is the second function block D started.

[0031] In a third query block E, it is checked whether the end stop in the first direction of rotation has been reached, i.e., whether the pin 7 of the drive wheel 6 rests against the closed groove 9a of the indexing gear 8 in the first direction of rotation. This is detected by recording an increase in the current draw of the electric motor 3 and by recording the rotational speed of the output shaft 11 of the electric motor 3, which is zero when the end stop is reached.

[0032] If no impact on the end stop could be detected (-) when querying the third query block E, the second function block D is repeated.

[0033] If, when querying the third query block E, a strike against the end stop in the first direction of rotation is detected (+), an incremental counter is activated in a third function block F to count the increments of the electric motor 3, which records the angular increments during the subsequent movement of the electric motor 3 in the second direction of rotation.

[0034] In a fourth functional block G, the electric motor 3 is actuated in the second direction of rotation.

[0035] In a fourth query block H, it is checked whether the end stop in the second direction of rotation has been reached, i.e., whether the pin 7 of the drive wheel 6 rests against or strikes the closed groove 9a of the indexing gear 8 in the second direction of rotation. This is detected by recording an increase in the current draw of the electric motor 3 and by recording the rotational speed of the output shaft 11 of the electric motor 3, which is zero when the end stop is reached.

[0036] If no impact on the end stop could be detected (-) when querying the fourth query block H, the fourth function block G is repeated.

[0037] If, when querying the fourth query block H, a strike against the end stop in the second direction of rotation is detected (+), the incremental counter is read in a fifth function block I and the number of counted increments of the electric motor 3 since activation of the incremental counter is stored in order to compare this with the number of intended increments of the electric motor 3 in a fifth query block J (plausibility check).

[0038] If the number of counted increments matches the number of planned increments of the electric motor (+), the stop positions have been validated. If the plausibility check is positive (+), a sixth function block K is executed, in which a difference between the current position of the switching shaft 5 and an ideal position of the switching shaft 5 is determined and stored in a non-volatile memory. Thus, the position of the switching shaft 5 is known.

[0039] If the plausibility check is negative (-), a seventh function block M is executed, which leads to an error entry (in the system). Reference sign 1 Electromechanical switching unit 2 Electromechanical switches 3 Electric motor 4-step gearbox 5 shift shaft 6 drive wheel 7 pen 8 Step gear wheel 9a Sealed groove 9b Unclosed (open) groove 10 Switch cam 11 Output shaft S Start of the procedure (triggering event; error case) A First query block B Second query block C First Function Block D Second Functional Block Third query block F Third functional block G Fourth Functional Block H Fourth query block I Fifth Functional Block J Fifth query block K Sixth Functional Block M Seventh Functional Block Yes - No

Claims

Electromechanical switching unit (1) for a motor vehicle comprising at least one electromechanical switch (2) and an actuator unit for switching the at least one electromechanical switch into at least two switching positions, namely a closed switching position and an open switching position, wherein the actuator unit comprises an electric motor (3) rotatable in two directions of rotation, namely in a first direction of rotation and in a second direction of rotation opposite to the first direction of rotation, a stepping gear (4) and a switching shaft (5), wherein the electric motor (3) is connected to the switching shaft (5) via the stepping gear (4) in a way that allows adjustment, and the switching shaft (5) is connected to the at least one electromechanical switch (2) in a way that allows adjustment.wherein the indexing mechanism (4) has a drive wheel (6) with a pin (7) effectively connected to the electric motor (3) and an indexing gear wheel (8) with at least two grooves (9a, 9b) effectively connected to the switching shaft (5), wherein the indexing mechanism (4) is designed such that when the drive wheel (6) rotates, the pin (7) periodically engages in the grooves (9a, 9b) of the indexing gear wheel (8) and thus causes an intermittent rotational movement of the indexing gear wheel (8) and thus of the switching shaft (5), wherein at least one groove (9a) of the indexing gear wheel (8) is closed so that the pin (7) of the drive wheel (6) cannot engage in this groove (9a) and thus at least one end stop is created in each direction of rotation of the electric motor (3). Electromechanical switching unit (1) according to claim 1, characterized in that the stepping gear wheel (8) has four circumferentially evenly distributed grooves (9a, 9b), wherein one groove (9a) of the four grooves (9a, 9b) is closed and three grooves (9b) of the four grooves (9a, 9b) are not closed. Electromechanical switching unit (1) according to claim 1 or 2, characterized in that the switching shaft (5) has at least one switching cam (10) which is connected to the electromechanical switch (2) in an adjustment-effective manner. Electromechanical switching unit (1) according to claim 3, characterized in that the switching shaft (5) has a number of switching cams (10) corresponding to the number of electromechanical switches (2), wherein each switching cam (10) is assigned to an electromechanical switch (2) in an adjustment-effective manner. Method for determining the position of a switching shaft (5) and thus a switching position of at least one electromechanical switch (2) of an electromechanical switching unit (1) according to one of claims 1 to 4 when a motor vehicle (A) is stationary and / or in the event of a motor vehicle (S) malfunction, comprising the following steps: - Approaching the end stop in the first direction of rotation of the electric motor (3) (D), - Detecting that the end stop has been reached in the first direction of rotation of the electric motor (3) by detecting an increase in the current consumption of the electric motor (3) and detecting a rotational speed of an output shaft (11) of the electric motor (3) that is zero (E), - Activating an incremental counter to count the increments detected during the subsequent movement of the electric motor (3) (F), - Approaching the end stop in the second direction of rotation of the electric motor (3) (G),- Detecting the reaching of the end stop in the second direction of rotation of the electric motor (3) by detecting an increase in the current consumption of the electric motor (3) and detecting a rotational speed of the output shaft (11) of the electric motor (3) that is zero (H), - Deactivating the incremental counter and recording the counted increments of the incremental counter (I), - Comparing the number of counted increments of the incremental counter with the number of intended increments of the electric motor (3) (J), wherein if the number of counted increments and the number of intended increments of the electric motor (3) match, the desired switching position is engaged and the position of the switching shaft is stored in a non-volatile memory (K), and if the number of counted increments and the number of intended increments of the electric motor (3) do not match, an error condition is output (M).

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