DE102006029349A1 - Anti-lock brake system regulation improving method for use in electronic brake system of passenger motor vehicle, involves determining loss or defect of brake circuit based on driving dynamics information of additional sensors of vehicle - Google Patents

Abstract

The method involves determining a loss or a defect of a brake circuit based on sensoric driving dynamics information of additional sensors of a passenger motor vehicle, where the additional sensors are not primary pressure sensors of a brake circuit (I). An anti-lock brake system (ABS) control program such as ABS wheel pressure controller and/or ABS wheel pressure model, that is utilized in the wheel pressure controller is modified depending on the determination. An independent claim is also included for a computer program product comprising a set of instructions for performing a method of improving a ABS-regulation in an electronic motor vehicle brake system.

Description

The The invention relates to a method according to the preamble of claim 1.

braking systems with ABS functionality are not only well-known in the field of passenger vehicles and widely used. These include in addition to the basic function ABS depending on the equipment variant often even more functions, such as ABSplus, ASR, ESP, ACC, etc., which partly use sub-functions of the ABS control system. The hydraulics Of the braking system is often for reasons of safety in two Broken brake circuits, whereby for cost reasons in only one of these circles (primary circuit) a pressure sensor for measuring the connected to the brake pedal Master cylinder controlled brake pressure is present.

One ABS control system contains usually several sub-functions, which are independent control programs represent. An independent one Control program is the so-called wheel pressure regulator, which of a parent Function which calculates pressure requirements is controlled (The term "program" is generally in the Meaning of a regulatory procedure and therefore not on a programmatic Implementation limited). The wheel pressure regulator then sets the desired wheel pressure as far as possible exactly one. The control quality an ABS control depends in a not to be neglected Measures of the control accuracy of the wheel pressure regulator. Will the printing requirements be inaccurate executed the ABS control can not as far as possible optimize the wheel Keep the slip area. One consequence of this is a loss of braking power, stability and steerability. A largely optimal regulation can be if there is a separate pressure sensor in each wheel brake circuit is. With a view to cost-effective production of the brake control systems However, often there are no Raddrucksensoren so that the for the Regulation necessary current wheel pressure determined via a wheel pressure model must become. To determine the wheel pressure via the wheel pressure model is However, at least information about the attached form needed from the driving times of the intake and exhaust valves on the close current wheel pressure to be able to. The wheel pressure regulator in which the wheel pressure model is realized thus uses the one measured with the sensor on the master cylinder Form as initial value for the determination of the current wheel pressure.

In a corresponding complex interaction of running side by side Regulatory processes, such as an electronically controlled vehicle dynamics control system the case may be especially then problems occur when individual components of the brake system are only partially or no longer available. For example, an inaccurate regulation can occur if a wheel pressure regulator due to a circuit failure in the wheels of a brake circuit no or no significant pressure can build more. In this Case bears only the orderly working Brake circuit for deceleration of the vehicle, whereby the legally prescribed minimum delay can be achieved got to. In case of failure of the primary circuit is also the system pressure information is no longer available. If the driver presses the brake, takes place at the intact brake circuit pressure build-up, while the System pressure sensor in the defective circuit initially indicates a residual pressure, the dependent from the remaining dynamic pressure is. If this one escapes, it becomes essentially no residual pressure is displayed. In today's braking systems it is therefore possible that in this case the brake system is not without doubt between can distinguish a defect of the sensor and a circular failure.

in the Case that the brake circuit comprising the pressure sensor (primary circuit) has failed, is the existing in the intact brake circuit system pressure for the Wheel pressure regulator unknown. If the wheel pressure regulator of a defective Sensor goes out, the pressure model defined in the Raddruckregler tried on a appropriate algorithm the wheel pressure even without the sensory gained Estimate form information. Usually this leads appraisal however, to a lower wheel pressure value.

If in the above-explained Situation where no pre-pressure sensor signal is available, the Driver by strongly entering the braking force increased so far that an ABS regulation begins, or the coefficient of friction suddenly changes towards smaller coefficients of friction The pressure settings of the ABS are not executed correctly because the wheel pressure regulator due to the unknown system pressure insufficient positioning accuracy having. this leads to ultimately to a low-quality ABS control because comparatively high Radgeschwin digkeitsoszillationen take place.

Of the primary circuit a generic, for example dual-circuit brake system is equipped with a pressure sensor, the secondary circuit comprises however, no own pressure sensor. In the event that a failure or defect of the brake circuit not equipped with a pressure sensor present (secondary circuit failure), is the sensory determined form information for the wheel pressure regulator as before available. Therefore, the printing requirements of the ABS the wheels of the undisturbed Braking circuit performed with the necessary quality.

From the WO 98/02339 Although a method for detecting a brake circuit failure using the wheel speed information is known, however, this information is only used to end a currently activated electronic brake force distribution.

The The object of the present invention is to improve the quality of a ABS control to improve if a failure or defect of a brake circuit is detected.

These The object is achieved by the method according to claim 1.

The Invention sets itself among other things the goal, the failure of a brake circuit preferably in the case of motor vehicle brake systems with diagonally split Brake circuits especially during a controlled braking, e.g. during an ABS stunt, too detect. In this way it is possible, preferably at a primary side Brake circuit failure to improve the ABS control.

Preferably is the detection of a failure of the defective circuit alone or together with other criteria based on the wheel and / or controller signals carried out.

When Criterion for a defective brake circuit is preferably alone or in common checked with other criteria, whether the sensed measured form below a predetermined Threshold and at the same time the vehicle deceleration above a predetermined threshold. The vehicle deceleration will preferably from the wheel speeds of all wheels of the Motor vehicle or formed from the vehicle reference speed.

In a brake system with diagonal brake circuit distribution is preferably the detection of a defective brake circuit is based on the front wheel, the in primary-side Brake circuit failure can still build up brake pressure and therefore in the ABS case control cycles passes.

One Another criterion for detecting a defective circuit is preferred checking if the Wheels of the failed brake circuit during a controlled braking with virtually no slippage and no pronounced wheel dynamics roll stable while the wheels have the intact brake circuit, slip, wheel dynamics and control activity.

• – aufeinanderfolgende, tiefe Schlupfeinläufe an einem Rad vorliegen, die bei einem Bremssystem mit ungestörten Brems kreisen in dieser Form nicht vorkommen können und/oder ob
• – gleichzeitig an Rädern des ausgefallenen Bremskreises eine geringe Dynamik und keine Regelaktivität oder nach einem gewissen Zeitraum keine Regelaktivität mehr festzustellen ist. Die Raddynamik und die Schlupfeinläufe können beispielsweise durch Betrachtung der Radbeschleunigungen bewertet werden.

Furthermore, it is additionally tested whether

• - Successive, deep slip enemas on a wheel present, the circuits in a brake system with undisturbed brake can not occur in this form and / or whether
• - At the same time on wheels of the failed brake circuit low dynamics and no rule activity or after a certain period no rule activity is no longer observed. The wheel dynamics and the slip enemas can be evaluated, for example, by considering the wheel accelerations.

Especially preferred according to the inventive method provided that if one or more, in particular all, the listed above Criteria met are, a circular failure is considered likely. In this case can For example, a circuit failure suspect flag may be set.

If, according to the above, the suspicion of a circular failure, for example recognizable that the Kreisausfallverdachts flag is set, preferably in a diagonal brake circuit arrangement in the course of further ABS control cycles of the slip of a front wheel of the intact brake circuit can be considered over a predetermined period. For example, if the maximum value of the relative slip ((V _{ref -V rad} ) / V _ref ) _exceeds a certain predetermined amount, a circular failure is considered to be detected. If this measure is not exceeded, but the conditions for the suspicion flag continue to be met, the suspicion is maintained and the subsequent control cycles are considered further.

To the method is also preferably provided that as soon as during the suspicious phase described above is a condition for setting the circle failure suspect flag is no longer satisfied, this is deleted again.

In addition, can preferably still tested whether an existing ESP system is currently not is active. This will prevent accidental ESP intervention is interpreted as a circular failure.

Farther the detection according to the invention is preferred a brake circuit failure suppressed or suppressed, if additional functions are active, the ratio of Vehicle delay and Affect system pressure, such as an automatic distance control (ACC).

Within of the wheel pressure model, according to the invention, both the wheel pressure, as well as the form modeled model.

Of the Form is preferably with the help of the calculated vehicle deceleration after a vehicle specific pressure / deceleration relationship, for example estimated on the basis of a table.

The Braking system in which the method described above is preferred for Use comes, includes Radausgangsseitige low-pressure accumulator, in the while a pressure reduction brake fluid is discharged, and a return pump, which conveys this fluid out of the low-pressure accumulator. It is appropriate, at a recognized Bremsreisausfall this return pump in particular with maximum To control speed to an intolerable excessive filling of the Low pressure accumulator, which are associated with insufficient pressure reduction would, to prevent.

To successful detection of the said circuit failure according to the invention, the ABS control program the brake system, in particular the ABS wheel pressure regulator and / or the ABS wheel pressure, modified, for example, in the switched to another mode becomes. This other mode of operation is preferably characterized by that a wheel pressure model is used, which is a Raddruckbestimmung not carried out using the sensory obtained form. The Pressure control on the wheel is in this case in particular fully model-based, i. E. There are no sensory gained pressure information by the pressure model processed.

Especially Preferably, the pump control described above with the previously described modification of the ABS control program combined.

The method described above can also be applied if the form sensor is detected as faulty or defective.

Basically it also possible as a result of the detection of a Bremskreisaufalls next to the above Modification of the ABS control also other driving dynamics functions, such as ABSplus, ASR, ACC, ESP, etc., in which the corresponding Function of the form on the basis of a form model based is placed.

The following 1 shows the basic structure of an electro-hydraulic brake control system. The electronic control in electronics unit 7 (ECU) is with a hydraulic unit 8th (HCU) connected such that hydrau likventile 2 . 3 . 3 ' . 4 and 6 can be controlled via valve coils. In hydraulic unit 8th There are control valves for two brake circuits I and II in which, in a diagonal arrangement, the wheels A and C are front wheels and the wheels B and D are rear wheels. circle I includes unlike circle II in the area of the input of the hydraulic circuit, a pre-pressure sensor 9 , form sensor 9 allows the driver's determination via tandem master cylinder 1 Controlled form by electronic unit 7 ,

In the area of the wheels, wheel speed sensors RDS are arranged, which provide wheel speed information to the electronics unit 7 to transfer. By evaluating the wheel speed information in the electronics unit 7 the need for anti-lock control (ABS) is established.

A pressure build-up takes place by pedal operation on a dual-circuit tandem master cylinder 1 (THZ) with upstream servo unit. To the two brake circuits I . II of the master cylinder are two wheel brakes A, B; C, D connected. Each brake circuit contains an electrically operated and electrically controllable hydraulic pump 5 , which serves as a force-fed pressure medium source. The components and the hydraulic circuit of the two brake circuits I . II are up on pressure sensor 9 essentially identical.

In each of the two brake circuits I . II are the wheel brakes A, B; C, D wheel-specific via analogue controllable or analogized intake valves 3 and a - each brake circuit - common isolation valve 2 with the brake pressure transducer 1 hydraulically connected. In addition, each wheel brake A, B; C, D via an outlet valve 4 and a low-pressure accumulator NDS with the suction side of the hydraulic pump 5 and via a normally closed switching valve 6 (SG valve) with the brake pressure transducer 1 connected; over the valve 6 can the hydraulic pump 5 If necessary, eg in the context of a specific traction slip or driving stability control process, suck in pressure medium from the master cylinder.

Claims (7)

A method for improving an ABS control in an electronic motor vehicle brake system, wherein the brake system comprises a plurality of brake circuits, of which at least one circuit has no pressure sensor for the form, characterized in that on the basis of sensory driving dynamics information of one or more other sensors of the motor vehicle a failure or Defect of a brake circuit is detected, the one or more sensors are not pre-pressure sensors of a brake circuit, and depending on this detection, the ABS control program, in particular the ABS wheel pressure regulator and / or the ABS wheel pressure model used in the wheel pressure regulator is modified. Method according to claim 1, characterized in that that the vehicle dynamics information based on the Radsensorsignale be won. A method according to claim 1, characterized in that the vehicle dynamics information based on the Radsensorsignale and the available driving dynamics in an ESP system sensors are obtained. Method according to at least one of claims 1 to 3, characterized in that the pending on the ABS intake valves Form is simulated model. Method according to claim 4, characterized in that that the form or master cylinder pressure with the help of the Wheel speeds calculated vehicle deceleration is estimated. Method according to at least one of claims 1 to 5, characterized in that the estimated pre-pressure or master cylinder pressure within the ABS wheel pressure model and / or within the ABS wheel pressure regulator is used as a form. Computer program product, characterized that this contains an algorithm which follows the procedure at least one of the claims 1 to 6.