Combined control device for the parking brake and park lock function of motor vehicles

The combined control unit is designed with a manual drive stage input unit (2) for the vehicle gear setting and an electronic selection signal unit (5) connected at vehicle control bus (1) also electronic gearbox control (7) connected to bus, which controls the actuators (8,9) for adjusting the gearbox in the respective desired gear stage signaled by the selection unit. An electronic hand brake unit (10) is provided with an electronic hand braking function control unit (11), also hand brake input unit (12) for deactivating-activating the hand braking function and an actuator (13) for the vehicle brake. A brake pedal sensor (14) is coupled to the control bus across an interface (15). The running control of the various components is carried out, so that with the choice of the parking setting at the drive stage input unit is established across the selection signaling unit and the control bus, activates the hand brake unit and the vehicle brake.

BACKGROUND OF THE INVENTION

The invention relates to a combined control device for the parking brake and park lock function of motor vehicles with automatic transmission or automated manual transmission. Parking brake function is to be understood here not only as the function of the parking brake which can conventionally be activated by a separate brake pedal on the left next to the customary configuration of pedals, but also the hand brake which can be activated by means of a stick lever on the center console.

With respect to the background of the invention it is to be noted that the aforementioned automatic transmissions provide various driving positions which are abbreviated with the letters P, R, N and D (P: Park, R: Reverse, N: Neutral, D: Drive). These driving positions are selected using a selector lever in the vehicle and correspond to the actual state of the transmission. Here, in the position D in, for example, a six-gearspeed automatic transmission, the various gearspeeds in the transmission are switched hydraulically. The actuation is carried out here by means of valves which are in turn actuated by an electronic transmission controller.

In the transmission designs which are currently used in series-produced vehicles, the connection between a participating hydraulic selector slide in the transmission and the selector lever in the interior of the vehicle is implemented by means of a linkage or a Bowden cable.

In order to secure the parked vehicle in the position P (parked position), what is referred to as park lock or shift lock is provided which prevents the parked vehicle from rolling away. The function of this park lock allows a driving position R or D to be selected from the selector lever position P only if the brake pedal and the ignition key are activated. In known automatic transmissions, this park lock is integrated into the transmission and acts on what is referred to as the notched plate. In fact a detent engages in the notched plate in the position P with spring force and thus prevents the activation of the selector lever. By activating the brake pedal and the ignition key, the detent is disengaged with a Bowden cable, and the notched plate is released. After it has left the selector lever position P, the detent can no longer engage as there are no corresponding latching recesses provided in the edge of notched plate. In this position, the Bowden cable is tensioned between the detent and brake pedal and releases the second Bowden cable to the ignition lock by means of a release lever on the brake pedal. As a result, the ignition key is prevented from being withdrawn by a locking slide in the ignition lock in the driving mode. In contrast, the ignition key can be withdrawn only if the Bowden cable is tensioned between the steering lock and brake pedal and releases the ignition key via the locking slide. This tensioning of the Bowden cable is carried out with the aforementioned tensioning lever by means of the second Bowden cable as soon as the detent has latched into the notched plate.

A known alternative to mechanically configuring the park lock is implemented using an integrated transmission controller, a separate actuator, e.g. a slide valve, electrically engaging the park lock and releasing it again. In this version, the aforementioned tensioning lever and the Bowden cable assigned to it can be dispensed with but an actuator and a mechanical tensioning device are still necessary.

Modern transmission designs such as will be included in the series production of vehicles in the short to medium term provide, for reasons of cost and quality, for the transmission electronics to be integrated directly into the transmission, which is referred to as “mechatronic transmission control”. The mechanical connection between the transmission and selector lever is dispensed with here. Instead, the position P, R, N or D of the selector lever in the interior of the vehicle is communicated to the transmission via electrical connections. This concept is referred to as “shift-by-wire”.

SUMMARY OF THE INVENTION

The invention is then based on the object of implementing a park lock function of an automatic transmission on the basis of the mechatronic transmission control and of the shift-by-wire concept and further vehicle functions.

This object can be achieved by means of a combined control device for the parking brake and park lock function of motor vehicles with automatic transmission or automated manual transmission, comprising:a manual driving-position input unit for the driving position of the vehicle,an electronic selection signaling unit which is connected thereto and is coupled to a vehicle control bus,an electronic transmission controller which is also connected to the vehicle control bus and drives actuators for placing the transmission in the respectively desired driving position which is signaled by the selection signaling unit,an electronic parking brake device comprisingan electronic parking brake function controller,a manual parking brake input unit, connected thereto, for deactivating/activating the parking brake function, andan actuator, also connected to the controller, for the vehicle brake,a brake pedal sensor, coupled to the vehicle control bus via an interface, for monitoring the activation of the brake pedal, anda sequence controller of the above components which, by means of the selection signaling unit and the control bus, activates the parking brake device and thus puts on the parking brake when the parked position is selected on the driving-position input unit.

Another embodiment is a control device for the parking brake and park lock function of motor vehicles comprising a manual driving-position input unit for the driving position of the vehicle, an electronic transmission controller which is also connected to a vehicle control bus and drives actuators for placing the transmission in the respectively desired driving position, an electronic parking brake device comprising an electronic parking brake function controller, and an actuator for the vehicle brake which is connected to the brake function controller, and a sequence controller coupled with the above components which, by means of the selection signaling unit and the control bus, activates the parking brake device when the parked position is selected on the driving-position input unit.

In this embodiment, the control device may further comprise an electronic selection signaling unit which is connected to the manual driving-position input unit and is coupled to the vehicle control bus and a manual parking brake input unit which is connected to the manual driving-position input unit for deactivating/activating the parking brake function. Furthermore, a brake pedal sensor can be provided, coupled to the vehicle control bus via an interface, for monitoring the activation of the brake pedal.

In all embodiments, when the parking brake is activated, the sequence controller can carry out electronic locking of the parked position, which can be released only be activating the brake pedal. When the parked position is activated, the sequence controller may also carry out electronic locking of the parking brake, which may be released only by deactivating the parked position. The manual driving-position input unit can be formed by a driving-position selector lever on the center console of the vehicle or a momentary-switch input unit on the steering wheel of the vehicle. The brake pedal sensor and its interface with the vehicle control bus can be part of the antilock brake system of the vehicle. When the ignition is switched off, the sequence controller can automatically activate the parked position. The sequence controller can also carry out a hill start aid function by automatically activating and deactivating the parking brake function.

A method of operating the parking brake and park lock function of motor vehicles according to the present invention comprises the steps of:monitoring a manual driving-position input unit for the driving position of the vehicle,activating a parking brake the parked position is selected on the driving-position input unit.

The method may further comprise the step of signaling the manual driving-position and can also comprise the step of monitoring the activation of a brake pedal. When the parking brake is activated, the sequence controller may carry out electronic locking of the parked position, which may be released only be activating the brake pedal. When the parked position is activated, the sequence controller can carry out electronic locking of the parking brake, which may be released only by deactivating the parked position. The method can further comprise the step of activating the parked position when the ignition is switched off. The method can further comprise the step of carrying out a hill start aid function by automatically activating and deactivating the parking brake function.

Basically, on the basis of the sequence control above, when the driving position P (park) is selected the vehicle brake is put on and the vehicle is thus prevented from rolling away.

Further blocking mechanisms, such as unintentional release of the brake or selection of driving positions in undefined vehicle states, can be prevented by some of the other features of the inventions.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In a shift-by-wire concept of an automated manual transmission or automatic transmission, the “backbone” is the vehicle control bus1which is implemented, for example, by a CAN bus. Not only the components, to be explained below, of the control device according to the invention but also other electronic controllers, for example what is referred to as the “keyless-go-system”, are also connected to this control bus1. A corresponding immobilizer function can be integrated into this system, said immobilizer function accessing the control bus1in precisely the same way as various diagnostic or safety-related systems.

On the one hand various components which are assigned to the actual transmission are relevant for the parking brake and park lock function, as is apparent from FIG.1. Thus, a driving-position input unit2is provided which comprises, for example, momentary switches on the steering wheel of the vehicle. Firstly, the desired driving position P, R, N or D is selected by means of these momentary switches. In addition, by means of these momentary switches3,4of the driving-position input unit the various gearspeeds 1-5 in a 5-gearspeed transmission are selected within the driving position D. In order to connect it to the vehicle control bus1, the driving-position input unit2is coupled to an electronic selection signaling unit5which transfers the information relating to the selected driving position/gearspeed, encoded in accordance with the bus protocol used, to the control bus1. In addition, the selection signaling unit5drives a display device6, for example in the form of a LCD display in the dashboard of the vehicle. There, the respectively selected driving position/gearspeed is displayed, as is indicated inFIG. 1by means of an arrow at the park position P.

The transmission complex also includes an electronic transmission controller7which is likewise connected to the vehicle control bus1. Said transmission controller7drives actuators8,9which set the selected driving position P, R, N or D and the corresponding gearspeed.

In addition, an electronic parking brake device is included in the entire control device, said parking brake device being in the present case a hand brake device10and an electronic hand brake function controller11which is connected to the vehicle control bus1. A manual hand brake input device12, which replaces the customary hand brake stick lever between the front seats of a vehicle, is assigned to this hand brake function controller11. The hand brake function is activated and deactivated by the driver by means of this hand brake input device12. The vehicle brake is put on by means of a hand brake actuator13which puts on the vehicle brake and releases it again by being driven by the hand brake function controller11.

Finally a brake pedal sensor14is provided which monitors the activation of the brake pedal and outputs a corresponding signal. The brake pedal sensor14is integrated here into the control device via the ABS system15which is likewise connected to the vehicle control bus1. Said ABS system15practically constitutes the interface between the vehicle control bus1and the brake pedal sensor14.

The sequence control of the components mentioned above, which is implemented in the combined control device for the hand brake and park lock function will now be explained with reference toFIG. 2as follows:Step20: There is an interrogation to determine whether the park position P has been selected on the driving-position input unit2by the driver; if yes (“y” in FIG.2), the currently desired driving position P is transferred to the electronic transmission controller7and the hand brake function controller11by the selection signaling unit5via the vehicle control bus1;Step21: The hand brake actuator13is then driven via the hand brake function controller11and the hand brake of the vehicle is continuously activated;Step22: A marker “locking of the hand brake” is set in the hand brake function controller11, i.e. the hand brake is electronically locked and can no longer be released via the hand brake input unit12using the two momentary switches16(“hand brake on”) and17(“hand brake off”);Step23: The parked position P is electronically locked in the selection signaling unit5so that the selection of a driving position R, N, D which differs from the driving position P is prevented;Step24: There is an interrogation via the vehicle control bus1to determine whether the brake pedal sensor14has set the brake signal and the brake is therefore depressed; if this is the case (“y” in FIG.2), the sequence controller moves on;Step25: The driving position P is released in the selection signaling unit5, i.e. the driver can input a different driving position R, N or D via the driving-position input unit2;Step26: There is an interrogation to determine whether a driving position which differs from P has been selected; if this is the case (“y” in FIG.2), the sequence controller moves on;Step27: The electronic locking of the hand brake in the hand brake function controller11is reset, i.e. so that the driver can release the hand brake again by means of the hand brake input unit12.

If the interrogation steps20,24and26receive as a result a “no” (“n” in FIG.2), the entire sequence routine is exited and restarted with a defined clock.

As optional functions it is also possible to implement what is referred to as an “auto-P function” and an “automatic” hill start aid function (referred to as “auto-hill-holder function”) on the basis of the control device according to the invention.

In the case of the auto-P function, an interrogation routine is used to determine whether the ignition of the vehicle is switched off. If this is the case, the driving position P is automatically engaged and the hand brake is activated.

The automatic hill-holder function is implemented in automatic transmissions by virtue of the fact that, as it were, a slow forward travel is initiated on gradients to counteract backward rolling of the vehicle. This is to be implemented in automated manual shift transmissions per se only by means of a slipping activation of the clutch, which is undesired for reasons of wear. On the basis of the present control device according to the invention it is now possible to implement an automatic hill-holder function by the control device activating the parking brake function by putting on the parking brake. As a result, the vehicle is held while the parking brake can be correspondingly released when the accelerator is depressed and forward travel is started.

In summary, the combined control device according to the invention for the parking brake and park lock function of motor vehicles with automatic transmission or automated manual shift transmission has various advantages:The components which are necessary for mechanically implementing the park lock function in the transmission, such as mechanical and hydraulic components with corresponding actuators and their drive electronics, can be dispensed with.The control device can also be used in vehicles with automated manual transmissions, while the park lock function which is implemented in customary transmission technology only in “genuine” automatic transmissions due to the design can be simulated without appreciable additional expenditure.Correspondingly, the modules for inputting the driving position which is desired by the driver or the desired gearspeed in the form of, for example, momentary switches on the steering wheel can be used as an equivalent of an automatic transmission and automated manual transmission.The hand brake can be engaged by selecting the park position by means of the driving-position input unit, in particular its gearspeed momentary switches. An additional manual activation can be dispensed with.The combined control device can also be implemented with an isolated transmission controller, that is to say one which is located for example in the engine compartment and is not integrated into the transmission.