Air guiding device for cooling the brakes in a motor vehicle

Abstract

Air guiding device for cooling the brakes in a motor vehicle with adjustable air guiding flaps and with an electronic control unit for controlling the air guiding flaps as a function of the vehicle speed (v) and of the pilot pressure (p) in the braking system triggered by the brake pedal actuation, wherein a first mode and a second mode for opening the air guiding flaps are provided in the control unit by means of a corresponding program module, wherein the second mode is directed towards a desire to prevent acceleration at a relatively low vehicle speed (v) and wherein the first mode is directed towards a desire to decelerate sharply at a relatively high vehicle speed (v) and provides for opening of the air guiding flaps,when the vehicle speed (v) exceeds a defined upper speed threshold (110 km / h) and the pilot pressure (p) is above a defined upper pressure threshold (80 bar) for a predetermined relatively short period of time (3 sec) for the first time or repeatedly, characterized in that in both the first and the second mode, after the air flaps have been opened, they are only closed again after a predetermined cooling period (10 min) has elapsed, starting when the pressure falls below the respective pressure threshold (80 bar; 4 bar).

Description

[0001] The invention relates to an air guiding device for cooling the brakes in a motor vehicle with adjustable air guiding flaps.

[0002] For example, DE 10 2010 037 615 A1 discloses an air guiding device with adjustable flaps for selectively cooling an internal combustion engine or the brakes in a motor vehicle. The exhaust air from the engine compartment is used for cooling. Brake cooling depends in particular on the strength and duration of the braking intervention or the temperature of the brake discs. Typically, a so-called temperature model is created for this purpose, taking into account a large number of parameters, and stored in a control unit for controlling the flaps.

[0003] From GB 2 269 144 A, a brake temperature control by means of controlled air supply is known, which takes place depending on parameter values ​​of certain measured variables.

[0004] The closest prior art, DE 10 2009 050 967 A1, describes a closable air duct cooling system for a motor vehicle brake, wherein the air duct cooling system is arranged on a front wheel housing and comprises at least one brake air duct arranged in a body and opening into the front wheel housing, on which a closing device is arranged, which is movable between a position closing the brake air duct and an opening position and has an actuating device which actuates the closing device as a function of a driving parameter, in particular a vehicle speed, a braking intensity or a brake temperature.

[0005] The object of the invention is to simplify an air guiding device for cooling the brakes.

[0006] This object is achieved according to the invention by the subject matter of patent claim 1. The dependent patent claim is an advantageous development of the invention.

[0007] Basically, the air-guiding device according to the invention for cooling the brakes comprises adjustable air-guiding flaps and an electronic control unit for controlling the air-guiding flaps as a function of the vehicle speed and the pilot pressure in the braking system triggered by the brake pedal actuation. A corresponding program module in the control unit provides a first mode and a second mode for opening the air-guiding flaps. The first mode is directed at a strong deceleration request at relatively high vehicle speeds—particularly on highways and country roads. The second mode is directed at a desire to prevent acceleration at relatively low vehicle speeds—particularly when driving downhill on mountain passes.

[0008] Since open flaps increase drag and fuel consumption, the invention only cools the brakes when there is increased demand. Furthermore, only two operating parameters are used for flap control, making the method very simple and robust to implement.

[0009] The drawing illustrates an embodiment of the invention. It schematically shows a motor vehicle with controllable air flaps K at least at the level of the wheel brakes, optionally also centrally toward the engine compartment.

[0010] The air flaps K are opened or closed by an electronic control unit 2 depending on the vehicle speed v and on the pilot pressure p in the braking system triggered by the brake pedal actuation. In the control unit 2, a corresponding program module provides a first mode "Mode 1" and a second mode "Mode 2" for opening the air guide flaps K. Mode 1 provides for the air flaps K to open when the vehicle speed v exceeds a defined upper speed threshold - here, for example, 110 km / h - and the pilot pressure p is above a defined upper pressure threshold - here, for example, 80 bar - for the repeated - here for the second - time for a predetermined, relatively short period of time - here, for example, 3 seconds.

[0011] Mode 2 provides for the opening of the air flaps K when the vehicle speed v exceeds a defined lower speed threshold value - here, for example, 15 km / h - and the pilot pressure p is above a defined lower pressure threshold value - here, for example, 4 bar - for a predetermined relatively long period of time - here, for example, 20 seconds.

[0012] Preferably, in both the first and second modes, after the air flaps K have been opened, they are only closed again after a predetermined cooling time has elapsed - here, for example, 10 minutes - starting when the pressure falls below the respective threshold value (here 80 bar or 4 bar).

[0013] This air damper control according to the invention is characterized by its reliability and simplicity.

Claims

[1] Air guiding device for cooling the brakes in a motor vehicle with adjustable air guiding flaps and with an electronic control unit for controlling the air guiding flaps as a function of the vehicle speed (v) and of the pilot pressure (p) in the braking system triggered by the brake pedal actuation, wherein a first mode and a second mode for opening the air guiding flaps are provided in the control unit by means of a corresponding program module, wherein the second mode is directed towards a desire to prevent acceleration at a relatively low vehicle speed (v) and wherein the first mode is directed towards a strong deceleration desire at a relatively high vehicle speed (v) and provides for an opening of the air flaps,if the vehicle speed (v) exceeds a defined upper speed threshold (110 km / h) and the pilot pressure (p) is above a defined upper pressure threshold (80 bar) for a predetermined relatively short period of time (3 seconds) for the first time or repeatedly, characterized by that in both the first and second modes, after the air flaps have been opened, they are only closed again after a predetermined cooling time (10 min) has elapsed, starting when the pressure falls below the respective threshold value (80 bar; 4 bar). [2] Air guiding device according to claim 1, characterized by that the second mode provides for the air flaps to be opened when the vehicle speed (v) exceeds a defined lower speed threshold (15 km / h) and the pilot pressure (p) is above a defined lower pressure threshold (4 bar) for a predetermined relatively long period of time (20 sec).

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