Machine element or mechanism – Gearing – Interchangeably locked
Reexamination Certificate
2000-11-27
2002-05-07
Wright, Dirk (Department: 3681)
Machine element or mechanism
Gearing
Interchangeably locked
Reexamination Certificate
active
06382041
ABSTRACT:
BACKGROUND AND SUMMARY OF THE INVENTION
This application claims the priority of German patent document 199 57 151.1, filed Nov. 27 1999, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a gearshift device for a motor vehicle.
In modern motor vehicles, the demands on gearshift devices are steadily increasing with respect not only to comfort, but also reliability, constructional space and weight, and with regard to supporting a driver of a motor vehicle. An advantageous effect can frequently be achieved by replacing mechanical components or assemblies by electronic components and assemblies.
As a rule, a gearshift device has an input unit for receiving input data or, a driver's request. In most cases, the input unit is constructed as a gearshift lever which is connected to a gearbox via a rod linkage.
U.S. Pat. No. 4,790,204, discloses a generic gearshift in which a mechanical connection between an input unit and an automatic gearbox is replaced by an electronic assembly, making it possible to reduce components, weight, constructional space and assembly effort. The input unit has an input device with pushbuttons for selecting from amongst various gearshift positions, such as, for example, a park position P, a neutral position N, a drive position D, etc. The input device is electrically connected via a controller to an actuating unit which is mounted on an outer side of a gearbox housing and acts on an actuating lever. When an accelerator pedal is completely pushed down, a second controller receives a signal and drives a kick-down lever on the gearbox by means of the actuating unit.
One object of the present invention is to provide a gearshift device of the generic type which achieves enhanced reliability and comfort.
This and other objects and advantages are achieved by the gearshift device according to the invention, in which an input unit for receiving input data is connected via at least one data line to a first controller for controlling an actuator unit for adjusting a gearbox (such as an automatic gearbox of a motor vehicle). At least one second controller is also provided, which is independent of the first controller, and is also connected to the input unit via at least one data line. In the case of a fault in the first controller, the actuator unit can be controlled by the second controller at least partially correspondingly to the first controller. Due to the second controller, a high reliability can be achieved without any additional mechanical assembly. Advantageously, the second controller is also used for monitoring the first controller; it receives at least in part (and preferably completely) the same input data as the first controller and performs at least partly (and preferably entirely) the same evaluation and comparing the output variables for the purpose of monitoring. This saves an additional monitoring unit.
In the case of a fault, and an unacceptable deviation of the output variables, the second controller deactivates the first controller and at least partially takes over the operation of the first controller, making it possible to avoid having an additional unit for disconnecting the first controller. In this arrangement, the controllers are advantageously connected to the actuator unit via tristate lines, which supply information and electrical power for the actuator unit. Having a direct data line between the controllers can be avoided. Furthermore, the tristate lines can be advantageously used for deactivating the first controller by means of the second controller, in that the tristate lines of the controllers are connected to one another; in the case of a fault, the second controller short-circuits at least one tristate line, thereby deactivating the first controller via a current limiter. A current limiter which, as a rule, already exists, can be additionally used for disconnecting the first controller, wherein the current limiter can be integrated in the controller or also constructed as a separate unit.
If a fault occurs while the controller (or the first controller) is in a deactivated state, the activator unit assumes or maintains a position in which a flow of force between the gearbox and an internal combustion engine is interrupted. Accordingly, it is always possible to achieve a safe state for the gearbox and, especially, for the motor vehicle and its passengers. This can be achieved by means of various known actuators; for example by means of a hydraulic actuator which, in the deactivated state, moves into an initial position by means of a spring force or, advantageously, by means of an electromagnetic actuator comprising a spring mechanism which, in the deactivated state, holds an armature in a neutral position between two pole faces of electromagnets. Starting with a safe state, the second controller can subsequently take over the control of the actuator unit.
The controllers are advantageously connected to a data network of the motor vehicle, as a result of which vehicle data such as speed, speed sense, temperature, etc. can be taken into consideration in controlling the actuator unit. It is possible to use existing sensors and avoid using additional sensors at least to a large extent. It is also possible to transmit information from the controllers to other controllers via the data network, for example the power of the internal combustion engine can be advantageously reduced in a deactivated state of the actuator unit in order to avoid unwanted high idling revolutions.
Apart from the control functions of the gearbox, one or both controllers can be used for other operations, for example for an engine control, etc., as a result of which additional components and constructional space can be saved.
In one embodiment of the invention, the actuator unit has at least one first actuator and one second actuator, which is independent of the first actuator. The first actuator is used, in normal operation, for setting a drive position and a neutral position at the gearbox, and the second actuator is used for operating a parking lock in a park position of the gearbox. In an automatic gearbox, a selector slide can be advantageously constructed with only three positions instead of four positions, which makes it possible to save costs and constructional space. Furthermore, additional degrees of freedom are obtained in the driving and in the arrangement of the actuators. The actuators can be advantageously driven independently of one another in various situations; for example a drive position D or R can be set at the gearbox by means of the first actuator when starting on an incline and the parking lock can only be released via the second actuator from a certain engine power on. This makes it possible to prevent a rolling movement of the motor vehicle in an unwanted direction and to save energy and reduce wear.
The second actuator can be constructed, for example, as an electric motor or electro-hydraulically.
If the second actuator is arranged in a housing of the gearbox, a compact assembly can be achieved which can be separately manufactured and checked for its operations. However, the second actuator and, in particular, the parking lock can also be arranged advantageously outside the gearbox housing, as a result of which the gearbox can be constructed in an especially space-saving manner. The second actuator can be integrated in a wheel hub of the motor vehicle or advantageously mounted on a chassis part. As a rule, a motor vehicle chassis is connected to wheels of the motor vehicle via a spring system, as a result of which the mass of the second actuator mounted on the chassis part advantageously belongs to the spring-mounted mass.
Furthermore, a parking brake can be preferably operated by means of a second actuator which is arranged outside the gearbox housing. It is possible to use one actuator for operating the parking brake and the parking lock and, as a result, to save one actuator. In an embodiment according to the invention, it is also proposed that the parking lock and the parking brake be con
Burgbacher Martin
Grieb Martin
Kroeger Torsten
Schmitfranz Bernd-Heinrich
Crowell & Moring LLP
DiamlerChrysler AG
Wright Dirk
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