Method of and Apparatus for Controlling a Plurality of Mutually Communicating Actuators

The present invention relates to a method and an apparatus for controlling a plurality of mutually communicating actuators.

German-"Offenlegungsschrift" 36 28 706 A1 discloses a central locking system in which each actuator of the central locking system is connected via a bus system to a central control unit evaluating a plurality of state parameters of doors registered by signal sensors of a plurality of individual actuators. A plurality of state signals are delivered from the signal sensors which are then converted in the central control unit to control signals for controllers of the actuators in accordance with a stored program. These control signals in turn are fed via the bus system to the controllers.

German-"Offenlegungsschrift" DE 42 19 212 A1 describes furthermore a central locking system in which each actuator has a control unit of its own which is fed both with data signals from signal sensors of the actuator and with selected data signals from signal sensors of other remaining actuators in the central locking system. Each control unit retrieves the signal information of the individual signal sensors of its actuator and, on the basis of these data signals and in accordance with selected data signals of the other actuators, calculates control signals for controllers of the central locking system and a theft protection system which are associated with the respective actuator. For transmitting the selected data signals, there is provided a bus system transmitting signals issued by the actuators in a time-division multiplex transmission mode.

Furthermore, German-"Offenlegungsschrift" DE 195 18 306 A1 discloses an apparatus for controlling a plurality of mutually communicating actuators of a convenience control system for motor vehicles. The convenience control system comprises, in addition to a central locking control system for a plurality of doors and a tailgate of a motor vehicle, a control system for a window lifting mechanism, outside mirrors, a lock/unlock switch on a driver's door, an interior illumination system as well as an overall diagnostic system. Each of the system components has an actuator of its own, whose controller is controlled either by a decentralized control unit of its own or directly by a control apparatus communicating with the decentralized control units.

In case of the known central locking or convenience control systems, a rapid temperature increase up to overheating causing a failure of the individual actuators or control units or of the entire system may occur both in the actuators and in the control units due to a large number of actuations primarily by the user.

According to principles of the present invention, a method of and an apparatus for controlling a plurality of mutually communicating actuators of a central locking or convenience control system are provided by means of which it is possible to prevent overheating of the actuators or a control apparatus in case of a multiplicity of actuations of the actuators.

According to an embodiment of the invention, a temperature of a plurality of individual actuators and/or of a control apparatus cooperating with the actuators is detected. The component (actuator or control apparatus) in which the temperature is measured is dependent upon the temperature sensitivity of the individual components. In case the temperature measured in a component exceeds a first temperature threshold value defined for the particular component, a control signal for non-driving controllers of the mutually communicating actuators is produced until the excessive temperature measured in the actuator or control apparatus has dropped below the first temperature threshold value by a defined temperature value. According to the embodiment of the invention, all controllers belonging to a functional group, for example the actuators of a central locking means, are not driven or operated until the temperature of the corresponding component has dropped below the first temperature threshold value by the defined temperature value.

According to a further embodiment of the invention, a safety actuation is permitted for each actuator while the first temperature threshold value is exceeded in a component. In the case of a central locking system, unlocking of the doors is still possible.

A further embodiment of the invention provides that a second temperature threshold value is defined having a value lower than that of the first temperature threshold value. When the second temperature threshold value is exceeded in an actuator or a control apparatus, a warning signal is generated and possibly displayed. It may be provided, furthermore, that the control of the controllers of the actuators is modified in response to the warning signal. In this respect, a possibility consists in increasing the time intervals between the control signals used for driving the controllers of the actuators.

The temperature is preferably detected directly in the control apparatus, for example by means of a temperature sensor implemented in the control apparatus. The temperature measurement in the actuators can be made by determining the number of actuations per unit of time.

An advantage of the embodiments of the invention resides especially also in that, when the temperature is exceeded in a component (actuator or control apparatus), not only the individual actuator is non-operable, but the entire functional system is put out of operation synchronously for a specific period of time, except for a permissible safety actuation. The vehicle user thus does not have the impression that a failure of the individual actuator is involved.

The invention will now be elucidated in more detail by way of an embodiment with reference to the associated drawings wherein

FIG. 1 is a block diagram of a convenience control system of a motor vehicle according to an embodiment of the invention.

FIG. 2 is a block diagram of a central locking system according to an embodiment of the invention.

FIG. 3 shows a possible pattern of the temperature in a control apparatus according to an embodiment of the invention.

FIG. 4 shows a temperature detection via a number of actuations in an actuator according to an embodiment of the invention.

A convenience control system according to an embodiment of the invention is shown in FIG. 1 containing a central locking system for a plurality of doors FL, FR, RL, RR and a tailgate TG, a control system for two window lifting mechanisms WL, WR, a control system for right and left outside mirrors ML, MR, a control system for a lock/unlock switch 7 on the door FL, an interior illumination IL as well as an overall diagnostic system. Each of the system components has an actuator of its own (FIG. 1 shows only actuators 1 to 4 of the central locking circuit), a controller of which is controlled either by a decentralized control apparatus E1 to E4 or directly by a central control apparatus CCA, with the lock/unlock switch 7 in the instant case being also controlled via the control apparatus E1. A data exchange between the control apparatus E1 to E4 and the central control apparatus CCA, in the embodiment, takes place via a bus system D, with each control apparatus E1 to E4 sending information under a specific identification to the central control apparatus CCA. The latter in turn transmits its data in the form of electrical transmissions associated with the individual actuators to the control apparatus E1 to E4. A temperature sensing circuit T determines the temperature in the control apparatus. The control apparatus CCA delivers an inhibiting signal to each of the controllers E1 to E4 to interrupt the movement of the actuators 1 to 4 when the temperature of any of the actuators or the control apparatus exceeds a first temperature threshold value.

In FIG. 2, an embodiment of the invention is illustrated by way of a control of the central locking system for the individual doors. Each of the doors FL, FR, RL, RR is provided with an electrically or pneumatically driven actuator 1 to 4 designed as a door lock and with the control apparatus E1 to E4 communicating with each other and with the central control apparatus CCA via the bus system D. Each of the actuators 1 to 4, depending on its site of use, has a different number of signal sensors 5a-5e. The signal sensors 5a of actuators 1 and 2 each supply a state signal 11 "open system" and the signal sensors 5b a state signal 12 "close system" to the control apparatus E1 and E2, respectively. They thus serve for control of the central locking system by a user. The signal sensors 5c and 5d of the actuators 1 to 4 each issue a state signal 13, 14 indicating whether the respective door is open or closed. The signal sensors 5e indicate whether a theft protection mechanism is activated through a state signal 15. The doors RL and RR have the actuators 3 and 4 that may not be operated by a user. For this reason, the corresponding signal sensors 5a and 5b are missing there. All signal sensors 5a-5e are provided in the form of Hall sensors or microswitches. Each of the control apparatus E1 to E4 of the actuators 1 to 4 continuously receives the state signals 11 to 15 of its own signal sensors 5a-5e as well as state information from other actuators via control apparatus of the latter and calculates therefrom a plurality of control signals S1, S2 for driving a plurality of motors M1 to M4 associated therewith. In addition thereto, all state signals 11 to 15 are also fed to the central control apparatus CCA which controls further functions, not shown, and is connected to a state display 6. The transmission of the state signals 11 to 15 between the control apparatus E1 to E4 and the central control apparatus CCA takes place in time-division multiplex transmission mode, with the central control apparatus CCA controlling the data traffic on the bus system D. In addition to the actuators 1 to 4, the control apparatus E1 to E4 may also control further actuators. For example, FIG. 2 shows a lock/unlock switch 7 on the door FL, the control of which is taken over by the control apparatus E1 via two additional electrical connections L1 and L2.

Due to a multiplicity of actuations of the individual actuators 1 to 4 effected by the user in a short period of time, overheating of individual actuators or control apparatus and in the extreme case failure of these components may occur. For avoiding overheating of the individual actuators 1 to 4 or the control apparatus E1 to E4, the temperature of these components is detected. This may take place in the control apparatus E1 to E4 via temperature sensors T implemented therein. When the temperature of one of the control apparatus E1 to E4 exceeds a lower temperature threshold value .sub.2 shown in FIG. 3, the control apparatus produces a warning signal which is communicated via the bus system D to all the other control apparatus E1 to E4. Due to the warning signal, the control signals S1 and S2 driving the motors M1 to M4 of the actuators 1 to 4 are modified such that the time interval between the driving operations of the actuators is increased. If the temperature in one control apparatus, e.g., E1, nevertheless exceeds an upper temperature threshold value .sub.1, a signal is fed to all the control apparatus E1 to E4 on the basis of which the actuators 1 to 4 are not driven until the temperature in control apparatus E1 has dropped below the upper temperature threshold limit .sub.1 by a defined temperature value .sub.h However, while the upper temperature threshold limit value .sub.1 is exceeded, it is still possible for safety reasons to operate the actuators once in order to be able to open the doors if necessary.

With respect to the actuators 1 to 4, the temperature may be determined by way of a detection of the number of actuations B per unit of time t. To this end, each actuator 1 to 4 has an actuation counter, C associated therewith, which is provided in the control apparatus E1 to E4. The actuation counter is incremented upon each actuation of the lock/unlock switch 7 when the time interval T.sub.p between actuations is smaller than a predetermined value T.sub.i. When the time interval T.sub.p is above the value T.sub.i, the actuation counter is decremented, in the embodiment shown in FIG. 4, by 2. When the actuation counter reaches the FIG. 50, the actuators 1 to 4 are not driven for a defined period of time T.sub.s. However, one single safety actuation B.sub.s "unlocking" is permitted. In this period of time T.sub.s, the actuation counter is decremented by 12, and driving of the actuators 1 to 4 is released again after expiration of the time period T.sub.s.