Parking brake with a release device

Abstract

The invention relates to a parking brake with a device for releasing the parking brake, in particular automatically, upon the presence of certain sensor and / or control input signals at a control unit, wherein, in order to release the parking brake, in particular automatically, at least one first input signal representing an ignition being switched on and at least one further input signal must be present at the control unit. The device is characterized in that the further input signal is alternatively either an actuation signal of a service brake or a signal for an open starting clutch or for an engaged parking lock of an automatic transmission.

Description

[0001] The invention relates to a parking brake with a device for releasing it, in particular automatically, when certain sensor and / or control input signals are present at a control unit.

[0002] Electrically controlled parking brakes with safety devices are already known. DE 41 29 502 A1 describes such a device, which prevents the parking brake from being actuated by the controls when the vehicle's electrical system is switched on via the ignition switch. This means that the parking brake cannot be actuated when the ignition is switched on, but after the vehicle's electrical system is switched off (i.e., when the ignition is off), the parking brake can be actuated freely and arbitrarily by the operator. One or two switches are provided as controls. The parking brake can only be released if the service brake is simultaneously applied, which is detected by a brake light switch. However, it is now common practice to also allow the parking brake to be released, particularly automatically, only when the ignition is switched on.Furthermore, it is common practice in electronic control systems to also use information available at the control unit, such as sensor status and / or signal status evaluations, for control decisions.

[0003] For the parking brake to be released, especially automatically, it is necessary to design the control system to be very restrictive against unwanted release, while at the same time it should also be possible to avoid having to tow the vehicle in the event of signal or sensor failures, for example.

[0004] The object of the invention is to provide a parking brake with such a device for releasing it, in particular automatically.

[0005] The problem is solved by the features of the first and second claims. Preferred embodiments of the invention are described in the dependent claims.

[0006] According to the invention, a parking brake of a motor vehicle with a manual transmission has a device for releasing it, in particular automatically, when certain sensor and / or control input signals are present at a control unit. For the parking brake to release, in particular automatically, at least one first input signal indicating that the ignition is switched on and at least one further input signal must be present at the control unit. The device is characterized in that the further input signal is alternatively either an actuation signal of a service brake or a signal for an open starting clutch.

[0007] In a motor vehicle with an automatic transmission, the parking brake also has a device for releasing it, in particular automatically, when certain sensor and / or control input signals are present at a control unit. For the parking brake to release, in particular automatically, at least one first input signal indicating that the ignition is switched on and at least one further input signal must be present at the control unit. The device is characterized in that the further input signal is alternatively either an actuation signal of a service brake or a signal for an engaged parking lock of an automatic transmission.

[0008] Both systems for releasing the parking brake, particularly automatically, have the advantage that the parking brake is released when one of two alternative signals from two different vehicle components is present. The control unit can query and evaluate the presence of the corresponding input signals from both vehicle components—service brake and launch clutch, or service brake and automatic transmission—sequentially or simultaneously. Should querying one vehicle component result in the parking brake not being released due to missing sensor signals, this decision can be immediately reversed by querying the other component, provided all query conditions for releasing the parking brake are met. Advantageously, the input signals from the service brake and the input signals from the launch clutch, respectively, are available simultaneously.The automatic transmission can be used redundantly by the control unit to prevent the vehicle from breaking down due to sensor failures or failures in signal transmission.

[0009] In an advantageous embodiment of the invention, the control unit also outputs a signal to release the parking brake when both other input signals are present at the control unit. Conversely, the parking brake is not released if the control unit does not output a signal to release the parking brake, that is, when neither of the other input signals is present at the control unit.

[0010] The probability of a vehicle breaking down due to a defect in the signal chain concerning the brake status and a defect in the signal chain concerning the clutch status or the automatic transmission status is very low because the control unit redundantly uses the input signals from the service brake and the input signals from the starting clutch or automatic transmission. Therefore, a control program branch that releases the parking brake, especially automatically, even though no information about the brake status or the clutch / automatic transmission status is available, is unnecessary.In this case, a further advantageous embodiment of the invention can be applied, namely, if neither of the other input signals is present at the control unit, the control unit requests and / or evaluates at least one additional input signal, and, if at least one additional input signal is present, outputs a signal to release the parking brake. This additional input signal can be entered by a driver via a control device. However, it can also be present in and / or evaluated by another control unit, resulting in an output signal to release or engage the parking brake.

[0011] If a fault occurs that prevents the control unit from receiving input signals regarding the brake, clutch, or automatic transmission status, the additional input signal prevents the vehicle from breaking down. The control unit can request this additional input signal from the driver via a display or from another control unit. It can also delegate the evaluation to another control unit.

[0012] Two preferred embodiments of the invention are described in more detail in the following description and the accompanying drawing. They show: Fig. 1: A flowchart of a parking brake control system according to the invention for a motor vehicle with a manual transmission and Fig. 2: a flowchart of a parking brake control system according to the invention for a motor vehicle with an automatic transmission.

[0013] In the Fig. In the flowchart shown for the release of an electrically controlled parking brake of a vehicle with a manual transmission, a parking brake release command is entered via a control element of the electric parking brake (EPB). A control unit that processes this input signal checks whether the ignition is switched on or off. In the latter case, the parking brake remains engaged, and the system is inactive. In the former case, with the ignition switched on, the operating states of the two vehicle components, the service brake and the starting clutch, are queried in parallel. The control unit first checks whether any operating state signals are present from the service brake or the clutch. If none are present, neither from the service brake nor from the starting clutch, which will likely be rare, the parking brake remains engaged. If one or both operating state signals from the service brake or the starting clutch are present, this or that signal is then used to release the parking brake.These conditions are evaluated in the control unit. As a result, the parking brake remains engaged if neither the clutch nor the service brake is depressed. If one or both conditions are answered with "yes," the parking brake is released.

[0014] It is taken for granted that, according to the invention, the two vehicle components, the starting clutch and the service brake, can also be evaluated one after the other by the control unit, in the event that the evaluation of the first vehicle component does not lead to the release of the parking brake.

[0015] In the Fig.In the flowchart shown in Figure 2 for the release of an electrically controlled parking brake of a motor vehicle with an automatic transmission, a parking brake release command is entered via a control element of the electric parking brake (EPB). A control unit that processes this input signal checks whether the ignition is switched on or off. In the latter case, the parking brake remains engaged, and the system is inactive. In the former case, with the ignition switched on, the operating states of the two vehicle components, the service brake and the automatic transmission, are queried in parallel. The control unit first checks whether any operating state signals are present from the service brake or the automatic transmission. If none are present, neither from the service brake nor from the automatic transmission, which will likely be rare, the parking brake remains engaged. If one or both operating state signals from the service brake or the automatic transmission are present, the corresponding signal is then released.These signals are evaluated in the control unit. As a result, the parking brake remains engaged if neither the automatic transmission is in Park (P) nor the service brake is applied. If one or both conditions are answered with "yes," the parking brake is released.

[0016] Here too, it is taken for granted that the two vehicle components automatic transmission and service brake can also be evaluated one after the other by the control unit according to the invention, in the case that the evaluation of the first vehicle component does not lead to the release of the parking brake.

[0017] Furthermore, if the parking brake is not released, the system may provide the driver with information, either audible or visual, indicating which operation to perform to release the parking brake. For example: "Please engage gear P" or "Please depress the clutch."

Claims

[1] Parking brake with a device for releasing it when certain sensor and / or control input signals are present at a control unit, wherein at least one first input signal representing an ignition being switched on and at least one further input signal must be present at the control unit to release the parking brake, characterized by that the further input signal is alternatively either an actuation signal of a service brake or a signal for an open starting clutch. [2] Parking brake with a device for releasing it when certain sensor and / or control input signals are present at a control unit, wherein at least one first input signal indicating that the ignition is switched on and at least one further input signal must be present at the control unit to release the parking brake, characterized bythat the further input signal is alternatively either an actuation signal of a service brake or a signal for an engaged parking lock of an automatic transmission. [3] Parking brake according to claim 1 or 2, characterized by , that the device for releasing the parking lock causes it to release automatically. [4] Parking brake according to one of claims 1 to 3, characterized by , that the control unit also outputs a signal to release the parking lock when both other input signals are present at the control unit. [5] Parking brake according to one of claims 1 to 4, characterized by , that the control unit does not output a signal to release the parking brake if neither one nor the other of the further input signals is present at the control unit. [6] Parking brake according to any one of claims 1 to 5, characterized by, that if neither one nor the other of the further input signals is present at the control unit, at least one additional input signal is requested and / or evaluated, and if at least the additional input signal is present, an output signal is issued to release the parking brake. [7] Parking brake according to claim 6, characterized by that the additional input signal can be entered by a driver via an operating device. [8] Parking brake according to claim 6 or 7, characterized by , that the additional input signal is present in another control unit and / or evaluated by it, to produce an output signal for releasing or engaging the parking brake.

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