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DE-102024133225-A1 - Procedure for putting a vehicle, braking system and vehicle into operation

DE102024133225A1DE 102024133225 A1DE102024133225 A1DE 102024133225A1DE-102024133225-A1

Abstract

In a method for limiting the maximum brake pressure during vehicle start-up, when a driver brake pressure is detected during a parking phase (P1) of the vehicle for starting the vehicle, the maximum brake pressure is electronically limited to an initial pressure (p1) that is lower than the maximum brake pressure when the vehicle is in motion (p3). The invention further relates to a brake system with a control unit configured to execute such a method, and to a vehicle with such a brake system.

Inventors

  • Christian Freund

Assignees

  • ZF ACTIVE SAFETY GMBH

Dates

Publication Date
20260513
Application Date
20241113

Claims (13)

  1. Method for limiting a maximum brake pressure when starting up a vehicle (10), in particular with an automatic transmission, comprising the step: a) when a driver brake pressure is detected in a parking phase (P1) of the vehicle (10) for starting the vehicle (10), the maximum brake pressure is electronically limited to an initial pressure ( p1 ) which is lower than a maximum brake pressure when the vehicle is moving ( p3 ).
  2. Procedure according to Claim 1 , characterized in that the initial pressure (p 1 ) to which the maximum brake pressure is limited is at least 25% lower than the maximum brake pressure when the vehicle is moving (p 3 ).
  3. Procedure according to Claim 1 or 2 , characterized in that the brake pressure, after being limited to the initial pressure (p 1 ), is increased to an intermediate pressure (p 2 ) after a defined period of time (Δt), in particular measured from the detection of an initial driver braking request, wherein the intermediate pressure (p 2 ) is lower than the maximum brake pressure when the vehicle is moving (p 3 ), in particular by at least 20%.
  4. Procedure according to Claim 3 , characterized in that the time period (Δt) is between 1 and 3 seconds.
  5. Procedure according to Claim 3 or 4 , characterized in that the initial pressure (p 1 ) is increased steadily and continuously to the intermediate pressure (p 2 ), in particular linearly.
  6. Procedure according to one of the Claims 3 until 5 , characterized in that an activated parking brake (24) of the vehicle (10) is only released when the maximum brake pressure is limited to the intermediate pressure (p 2 ).
  7. Procedure according to one of the Claims 3 until 6 , characterized in that the maximum brake pressure is increased to the maximum brake pressure when the vehicle starts moving ( 10 ) and/or as soon as an acceleration request from the driver is detected.
  8. Procedure according to one of the Claims 3 until 7 , characterized in that the intermediate pressure (p 2 ) is determined as a function of the inclination (α) of the vehicle (10).
  9. Procedure according to one of the Claims 3 until 8 , characterized in that the intermediate pressure (p 2 ) remains constant until the vehicle starts moving (10) and/or remains until a driver's acceleration request is detected.
  10. Method according to one of the preceding claims, characterized in that the initial pressure (p 1 ) is determined as a function of the inclination (α) of the vehicle (10).
  11. Method according to one of the preceding claims, characterized in that the method is carried out in a brake-by-wire braking system.
  12. Braking system (20) for a vehicle (10), in particular with automatic transmission, comprising a control unit (28) configured to perform the method according to one of the preceding claims, in particular with a brake-by-wire braking system.
  13. Vehicle (10), in particular with automatic transmission, with a braking system (20) according to Claim 12 , in particular a brake-by-wire braking system.

Description

The invention relates to a method for starting up a vehicle, in particular one with an automatic transmission. The invention further relates to a braking system for a vehicle, in particular one with an automatic transmission, comprising a control unit configured to perform such a method. The invention further relates to a vehicle, in particular one with an automatic transmission, comprising such a braking system. To start a vehicle with an automatic transmission, it is usually necessary to press the brake pedal so that the ignition can be triggered and the vehicle or its engine can start. Driven by an irrational need for safety, drivers often apply the brakes unnecessarily hard to ensure the vehicle remains stationary. This subjects the braking system to unnecessarily high stress, which can lead to increased wear. The object of the invention is to provide a method for starting a vehicle that reduces wear on the braking system. A further object of the invention is to provide a braking system and a vehicle with such a braking system in which the wear on the braking system is reduced when starting the engine. The problem is solved by a method for limiting the maximum brake pressure during the start-up of a vehicle, especially one with an automatic transmission, by the step: a) If a driver brake pressure is detected during a parking phase of the vehicle in order to start the vehicle, the maximum brake pressure will be electronically limited to an initial pressure that is lower than a maximum brake pressure when the vehicle is moving. For the purposes of the invention, maximum brake pressure is understood to be the maximum pressure applied to the vehicle's brakes at a given time, regardless of the driver's brake pressure or braking request, which is detected, for example, by actuating the brake pedal. During the parking phase, the vehicle is stationary and the vehicle's parking brake is engaged. It was discovered according to the invention that high brake pressures are not required to hold the vehicle stationary during the parking phase. By limiting the maximum brake pressure to a correspondingly low initial pressure during commissioning, regardless of whether the driver's braking request would actually correspond to a higher brake pressure, the loads to which the braking system is subjected are also effectively limited. In this way, the braking system is only subjected to a maximum load that prevents unnecessarily high wear of the braking system, regardless of the level of driver braking pressure, i.e., regardless of how hard the driver presses the brake pedal. According to one embodiment, the initial pressure to which the maximum braking pressure is limited is at least 25% lower than the maximum braking pressure when the vehicle is in motion, in order to effectively reduce the load and thus the wear of the braking system. According to a further embodiment, after being limited to the initial pressure, the brake pressure is increased to an intermediate pressure after a defined period, in particular measured from the detection of an initial driver braking request. This intermediate pressure is lower than the maximum brake pressure when the vehicle is moving, in particular by at least 20%. Thus, even in the phase after the vehicle has been started but is still stationary, the load on the brake system is limited and its wear is reduced accordingly. This period can range from 1 to 3 seconds. This corresponds to the length of time a driver typically maintains excessive pressure on the brake pedal after ignition before regaining the confidence that the vehicle can be held stationary even with less brake pressure. Additionally or alternatively, the initial pressure can be increased steadily and continuously to the intermediate pressure, particularly linearly. This ensures that the maximum braking pressure also increases steadily and continuously, thus preventing sudden load changes that could cause excessive wear. In one embodiment, an activated parking brake of the vehicle is only released when the maximum brake pressure is limited to the intermediate pressure. This ensures that the brake pressure is sufficiently high to reliably hold the vehicle stationary even when the parking brake is deactivated. Furthermore, it may be provided that the maximum brake pressure is applied when the vehicle starts moving and/or as soon as the driver requests acceleration. The system detects the vehicle's speed and increases the brake pressure to the maximum level while it is in motion. This ensures that full brake pressure is available as soon as the vehicle starts moving. In another embodiment, the intermediate pressure is determined based on the vehicle's inclination. The inclination corresponds to the gradient of the road surface or the standing surface on which the vehicle is parked. In this way, the brake pressure is sufficiently high to reliably hold the vehicle stationary on an inclined plane with the parking brake deactivated.