WO1998002339A1 - Double circuit braking system equipped with a device for recognising a front axle braking system breakdown - Google Patents
Double circuit braking system equipped with a device for recognising a front axle braking system breakdown Download PDFInfo
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- WO1998002339A1 WO1998002339A1 PCT/EP1997/003403 EP9703403W WO9802339A1 WO 1998002339 A1 WO1998002339 A1 WO 1998002339A1 EP 9703403 W EP9703403 W EP 9703403W WO 9802339 A1 WO9802339 A1 WO 9802339A1
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- brake
- front axle
- axle
- wheel
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
- B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
- B60T8/32—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration
- B60T8/88—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration with failure responsive means, i.e. means for detecting and indicating faulty operation of the speed responsive control means
- B60T8/885—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration with failure responsive means, i.e. means for detecting and indicating faulty operation of the speed responsive control means using electrical circuitry
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
- B60T2270/00—Further aspects of brake control systems not otherwise provided for
- B60T2270/40—Failsafe aspects of brake control systems
- B60T2270/403—Brake circuit failure
Definitions
- the present invention relates to a brake system according to the preamble of claim 1.
- brake systems are used, for example, for electronic brake force distribution.
- Electronic brake force distribution lowers the rear axle brake pressure during pedal-operated braking when the brake slip on the rear axle is excessive in order to prevent the rear wheels from locking in front of the front wheels.
- optimal slip is set, but only a reduced brake pressure. This can mean that the possible braking force on the rear axle may not be optimally used.
- With an intact brake system in which the greatest braking torque is applied anyway by the front axle brakes, this is not critical. However, if the front axle brake circuit fails, the optimum vehicle deceleration must be achieved on the rear axle in order to comply with legal standards.
- the present invention has for its object to provide a brake system of the type mentioned, in which the effort to detect a front axle brake circuit failure is reduced.
- the invention can therefore completely dispense with a pressure switch. Instead of monitoring a pressure switch, the brake circuit is now monitored directly on the software side.
- the invention makes use of the fact that when driving straight ahead, the speed of the rear wheels during braking with the front axle brake circuit intact differs only slightly from that of the front wheels. However, if the slip on the rear wheels exceeds a certain value over a long period of time, even though the independent wheel deceleration of the front wheels essentially corresponds to the vehicle deceleration, this is usually because the front wheels are not braked at all. The front axle brake circuit has therefore failed.
- a simple criterion which can be detected solely on the basis of the wheel sensor signals, is represented by the speed differences between the left and right wheels of an axle. If these speed differences on the front and on the rear axle are rectified and they exceed a certain threshold, then there is a cornering .
- Interventions in the wheel turning behavior that do not make the aforementioned plausibility criteria applicable are also carried out in the case of brake slip control.
- an anti-lock braking system in the brake system has the option of taking action to block the rear wheels in good time.
- the brake pressure can be built up immediately. This means that an immediate exit from the electronic brake force distribution can take place. This is based on the consideration that in the event of a vehicle deceleration, which can also be achieved by the rear axle brake circuit alone, with a maximum brake pressure of around 30 bar, provided the front axle brake circuit is not defective. If, however, a sudden pressure build-up on the rear axle is erroneously carried out in such pressure ranges, no vehicle instabilities are to be expected due to the low brake pressure.
- the first situation is as follows: The vehicle is driving straight ahead and is currently being subjected to pedal-operated braking, the slip values not yet being so critical that brake slip control would be necessary. If the independent wheel deceleration of the front wheels moves within a certain range around the vehicle deceleration, the slip sum of the rear wheels is formed. If this slip sum is greater than 1%, for example, i.e. that the rear axle wheels run deeper in the slip than the front axle wheels, a counter is started to record the time of this state.
- the counter is stopped or not started at all if the amount of vehicle deceleration exceeds 0.5 g. Such a vehicle deceleration can usually only be achieved with two intact brake circuits. The counter only continues counting when this vehicle deceleration threshold is again undershot.
- a front axle brake circuit failure is assumed. If an electronic brake force distribution is currently running, it is switched to phase 3. tet, that is, a quick pressure build-up grid is started in order to adapt the rear axle brake pressure to the uncontrolled brake pressure coming from the master cylinder. This switchover to phase 3 is independent of which phase of the electronic brake force distribution is taking place at the time a front axle brake circuit failure is detected.
- the pressure build-up pulse grid is used to give a device for anti-lock control the possibility of timely intervention when the back pressure is high due to the build-up of brake pressure at high admission pressure, i.e. high unregulated brake pressure.
- a cornering can be detected, for example, by determining the difference in the individual wheel speeds between the left and right wheels for the front axle and the rear axle. If both speed differences are rectified and if both speed differences are, for example, greater than a threshold value of 1 km / h, it can be assumed that a curve is being driven through. In such a case, the criteria for driving straight ahead are not applicable due to the influence of geometry and the rolling movement of a vehicle. For example, 1% slip is often present on the inside rear wheel due to the influence of geometry. Wheel vibrations on the inside of the front wheel are also possible due to the relief on the inside of the vehicle.
- the speed differences on the front and rear axles are compared with each other when cornering. If the front axle brake circuit fails, it can be seen on the rear axle that the rear wheel on the inside of the curve runs in higher slip than the other vehicle wheels. This means that the speed difference of the rear axle is significantly larger than that of the front axle. In this case, the criterion for starting a counter for time recording can be determined with the same speed differences ⁇ v h behind and
- the start of the time counter should be linked to the condition that the vehicle is decelerated more than 0.3 g. If the vehicle deceleration exceeds 0.3 g, the fulfillment of the speed difference criterion cannot be interpreted as a front axle brake circuit failure, since such high delays during cornering usually lead to entry into the brake slip control if a brake circuit has failed. So if the brake system is not in a brake slip control, but the vehicle deceleration is large, it can be concluded that the front axle brake circuit is intact.
- a front axle brake circuit failure is also assumed during cornering. If an electronic brake force distribution is currently running, no pressure build-up pulse grid has to be started but the electronic brake force distribution can be left immediately. The pressure in the rear axle brakes is therefore immediately adapted to the unregulated upstream pressure. This increases the comfort in the driver's pedal feel. This measure is not critical, because if the front axle brake circuit failure is detected incorrectly, the small deceleration, which is a prerequisite for the detection, can be achieved with a low brake pressure. This is around 30 bar. If a brake circuit failure is detected incorrectly, an immediate pressure build-up on the rear axle is harmless to the driving behavior, since such low brake pressures are unable to cause the rear wheels to slip excessively.
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- Transportation (AREA)
- Mechanical Engineering (AREA)
- Regulating Braking Force (AREA)
Abstract
Description
Zweikreisige Bremsanlage mit einer Einrichtung zur Erkennung eines Vorderachs-BremskreisausfallsDouble-circuit brake system with a device for detecting a front axle brake circuit failure
Die vorliegende Erfindung betrifft eine Bremsanlage gemäß dem Oberbegriff des Anspruchs 1. Derartige Bremsanlagen finden beispielsweise Verwendung zur elektronischen Bremskraftverteilung. Eine elektronische Bremskraftverteilung senkt während einer pedalbetätigten Bremsung bei überhöhtem Bremsschlupf an der Hinterachse den Hinterachsbremsdruck ab, um ein Blockieren der Hinterräder vor den Vorderrädern zu verhindern. Dabei wird nicht, wie es bei einer Blockierschutzregelung üblich ist, ein optimaler Schlupf eingestellt, sondern lediglich ein verminderter Bremsdruck. Dies kann dazu führen, daß unter Umständen an der Hinterachse die mögliche Bremskraft nicht optimal ausgenutzt wird. Bei einer intakten Bremsanlage, bei welcher das größte Bremsmoment ohnehin von den Vorderachsbremsen aufgebracht wird, ist so etwas unkritisch. Wenn jedoch der Vorderachsbremskreis ausfällt, so muß an der Hinterachse die optimale Fahrzeugverzögerung erzielt werden, um gesetzlichen Normen gerecht zu werden. Wenn der Vorderachs-Bremskreis ausfällt, so darf also keine elektronische Bremskraftverteilung in Form einer Bremsdrucksenkung oder eines Bremsdruckhaltens an der Hinterachse vorgenommen werden. Eine Bremsschlupfregelung, welche das Blockieren der Hinterräder verhindert, kann und soll nach wie vor auch bei Vorderachs-Bremskreisausfall erfolgen. Um beim Ausfall des Vorderachs-Bremskreises also eine elektronische Bremskraftverteilung auszuschalten bzw. nicht einsetzen zu lassen, ist es notwendig, einen solchen Ausfall zu detektieren. Hierzu gibt es die Maßnahme, daß im Vorderachs-Bremskreis ein Druckschalter angeordnet ist, der einen Bremsdruck erfaßt. Wenn bei betätigtem Bremspedal am Druckschalter kein Brems- druck ansteht, so ist davon auszugehen, daß der Vorderachs- Bremskreis ausgefallen ist. Allerdings ist ein Druckschalter als zusätzliches Bauteil immer auch der Gefahr eines Defektes ausgesetzt. Bei defektem Druckschalter kann allerdings ein Vorderachs-Bremskreisausfall nicht erkannt werden. Es bedarf daher einer zusätzlichen Überwachung des Druckschalters .The present invention relates to a brake system according to the preamble of claim 1. Such brake systems are used, for example, for electronic brake force distribution. Electronic brake force distribution lowers the rear axle brake pressure during pedal-operated braking when the brake slip on the rear axle is excessive in order to prevent the rear wheels from locking in front of the front wheels. It is not, as is customary with anti-lock control, that optimal slip is set, but only a reduced brake pressure. This can mean that the possible braking force on the rear axle may not be optimally used. With an intact brake system, in which the greatest braking torque is applied anyway by the front axle brakes, this is not critical. However, if the front axle brake circuit fails, the optimum vehicle deceleration must be achieved on the rear axle in order to comply with legal standards. If the front axle brake circuit fails, no electronic brake force distribution in the form of a brake pressure reduction or brake pressure maintenance on the rear axle may be carried out. Brake slip control, which prevents the rear wheels from locking, can and should still be done even if the front axle brake circuit fails. In order to switch off or not to use an electronic brake force distribution in the event of failure of the front axle brake circuit, it is necessary to detect such a failure. For this purpose, there is the measure that a pressure switch is arranged in the front axle brake circuit, which detects a brake pressure. If there is no brake pressure is present, it can be assumed that the front axle brake circuit has failed. However, a pressure switch as an additional component is always exposed to the risk of a defect. If the pressure switch is defective, however, a front axle brake circuit failure cannot be detected. Additional monitoring of the pressure switch is therefore required.
Die vorliegende Erfindung hat die Aufgabe, eine Bremsanlage der eingangs genannten Art zu schaffen, bei welcher der Aufwand zur Erkennung eines Vorderachs-Bremskreisausfalls verringert ist.The present invention has for its object to provide a brake system of the type mentioned, in which the effort to detect a front axle brake circuit failure is reduced.
Diese Aufgabe wird gelöst in Verbindung mit den kennzeichnenden Merkmalen des Anspruchs 1. Die Erfindung kann also völlig auf einen Druckschalter verzichten. Anstelle einer Überwachung eines Druckschalters erfolgt nunmehr software- seitig eine direkte Überwachung des Bremskreises. Die Erfindung macht sich dabei zunutze, daß bei einer Geradeausfahrt die Geschwindigkeit der Hinterräder während einer Bremsung bei intaktem Vorderachsbremskreis nur um einen geringen Wert von der der Vorderräder abweicht. Überschreitet jedoch der Schlupf an den Hinterrädern über längere Zeit einen bestimmten Wert, obwohl die Einzelradverzögerung der Vorderräder im wesentlichen der Fahrzeugverzögerung entspricht, so liegt das in der Regel daran, daß die Vorderräder gar nicht gebremst werden. Der Vorderachs-Bremskreis ist also ausgefallen. Diese Betrachtungen gelten zumindest, solange das Fahrzeug sich stabil verhält. Bei beginnender Blockierschutzregelung sind derartige Betrachtungen nicht aussagekräftig, da die einzelnen Fahrzeugräder u.U. bis zu einem Schlupf von 50 % gebracht werden. Bei einer stabilen Bremsung kann zwar auch zeitweilig an der Hinterachse die Schlupfsumme größer als 1 % werden, allerdings hält dieser Zustand bei funktionierender elektronischer Bremskraftverteilung nicht lange vor. Nur dann, wenn der Vorderachs-Bremskreis ausgefallen ist, tritt auch bei Druckabsenkung an der Hinterachse ein signifikanter Schlupf auf, da die Gesamtfahrzeugverzögerung nur über die Hinterachsbremsen erzielt werden muß und über die Hinterräder entsprechend höhere Längskräfte übertragen werden. Dies macht sich die Erfindung zunutze, indem vorzugsweise bei Auftreten von mindestens 1 % Schlupf an der Hinterachse ein Zeitzähler aktiviert wird, der bei Erreichen einer bestimmten Zeitspanne in diesem Zustand einen Vorderachs-Bremskreisausfall annimmt .This object is achieved in connection with the characterizing features of claim 1. The invention can therefore completely dispense with a pressure switch. Instead of monitoring a pressure switch, the brake circuit is now monitored directly on the software side. The invention makes use of the fact that when driving straight ahead, the speed of the rear wheels during braking with the front axle brake circuit intact differs only slightly from that of the front wheels. However, if the slip on the rear wheels exceeds a certain value over a long period of time, even though the independent wheel deceleration of the front wheels essentially corresponds to the vehicle deceleration, this is usually because the front wheels are not braked at all. The front axle brake circuit has therefore failed. These considerations apply at least as long as the vehicle is stable. When the anti-lock control system begins, such considerations are not meaningful, since the individual vehicle wheels may be brought up to a slip of 50%. When the brakes are stable, the total slip at the rear axle can also temporarily exceed 1%, but this state does not last long if the electronic brake force distribution is working. Only if the front axle brake circuit has failed significant slip occurs even when the pressure on the rear axle is reduced, since the total vehicle deceleration only has to be achieved via the rear axle brakes and correspondingly higher longitudinal forces are transmitted via the rear wheels. This makes use of the invention, in that a time counter is activated preferably when at least 1% slippage occurs on the rear axle and assumes a front axle brake circuit failure in this state when a certain time span is reached.
Diese Überlegungen gelten allerdings nur bei Geradeausfahrt. Daher empfiehlt es sich, zwischen Geradeausfahrt und Kurvenfahrt zu unterscheiden. Ein einfaches Kriterium, welches allein anhand der Radsensorsignale erfaßt werden kann, stellen die Geschwindigkeitsdifferenzen jeweils zwischen linkem und rechtem Rad einer Achse dar. Sind diese Geschwindigkeitsdifferenzen an der Vorder- und an der Hinterachse gleichgerichtet und überschreiten sie eine bestimmte Schwelle, so liegt eine Kurvenfahrt vor.These considerations only apply when driving straight ahead. It is therefore advisable to distinguish between driving straight ahead and cornering. A simple criterion, which can be detected solely on the basis of the wheel sensor signals, is represented by the speed differences between the left and right wheels of an axle. If these speed differences on the front and on the rear axle are rectified and they exceed a certain threshold, then there is a cornering .
Bei Kurvenfahrt gibt es andere geeignete Kriterien zur Erkennung eines Vorderachs-Bremskreisausfalls. Naturgemäß läuft ein kurveninneres Rad langsamer als das zugehörige kurvenäußere Rad derselben Achse. Ist allerdings die Geschwindigkeitsdifferenz zwischen den Hinterrädern für eine bestimmte Zeit um ein bestimmtes Maß größer als die Geschwindigkeitsdifferenz der Vorderräder, so ist dies ein Indiz für eine Vorderachs-Bremskreisausfall. Dieser Schluß ergibt sich daraus, daß beim Durchfahren einer Kurve das Fahrzeug eine seitliche Wankbewegung vollzieht. Die kurveninneren Räder werden entlastet, so daß sie nicht so große Bremskräfte übertragen können wie die kurvenäußeren Räder. Wenn diese Geschwindigkeitsdifferenz zwischen linkem und rechtem Rad an der Hinterachse aber deutlich größer ist als an der Vorderachse, so läßt sich daraus schließen, daß lediglich an der Hinterachse Längskräfte in Form einer Brem- sung übertragen werden, während die Vorderräder nur rollen. Das bedeutet also, daß der Vorderachs-Bremskreis ausgefallen ist .When cornering, there are other suitable criteria for detecting a front axle brake circuit failure. Naturally, a wheel on the inside of the curve runs slower than the associated outside wheel on the same axis. However, if the speed difference between the rear wheels is for a certain time larger than the speed difference between the front wheels, this is an indication of a front axle brake circuit failure. This conclusion arises from the fact that the vehicle makes a sideways roll movement when cornering. The wheels on the inside of the curve are relieved, so that they cannot transmit braking forces as great as the wheels on the outside of the curve. If this speed difference between the left and right wheel on the rear axle is significantly larger than on the front axle, it can be concluded that longitudinal forces in the form of a brake only on the rear axle. solution while the front wheels are only rolling. So this means that the front axle brake circuit has failed.
Da all diese Überlegungen Plausibilitätsüberlegungen sind, empfiehlt es sich, bestimmte Zusatzkriterien einzuführen, die den ermittelten Zustand verifizieren. Beispielsweise kann auch bei Erfüllung aller vorgenannter Kriterien der Vorderachs-Bremskreis nicht ausgefallen sein, wenn das Fahrzeug so stark verzögert, wie es nur mit zwei intakten Bremskreisen möglich ist.Since all of these considerations are plausibility considerations, it is advisable to introduce certain additional criteria that verify the determined condition. For example, even if all of the above criteria are met, the front axle brake circuit cannot fail if the vehicle decelerates as much as is possible with only two intact brake circuits.
Auch werden bei einer Bremsschlupfregelung Eingriffe in das Raddrehverhalten vorgenommen, die die zuvor genannten Plau- sibilitätskriterien nicht anwendbar machen.Interventions in the wheel turning behavior that do not make the aforementioned plausibility criteria applicable are also carried out in the case of brake slip control.
Wenn einer dieser beiden zuletztgenannten Fälle zutrifft, so sollte auch bei Erfüllung der anderen Kriterien für die Erkennung eines Vorderachs-Bremskreisausfalls ein solcher Ausfall nicht angenommen werden und entsprechend auch keine Maßnahmen getroffen werden, die die Fahrzeugverzögerung heraufsetzen sollen.If one of the latter two cases applies, then even if the other criteria for the detection of a front axle brake circuit failure are met, such a failure should not be assumed and correspondingly no measures should be taken to increase the vehicle deceleration.
Bei erkanntem Vorderachs-Bremskreisausfall muß in Folge bei Bremsanlagen mit elektronischer Bremskraftverteilung einer Unterbremsung vorgebeugt werden. Während einer Geradeausfahrt empfiehlt sich, den Hinterachs-Bremsdruck durch ein schnelles Druckaufbaupulsraster dem ungeregelten Bremsdruck anzupassen. Durch den gepulsten Druckaufbau hat ein Anti- blockiersystem der Bremsanlage die Möglichkeit, rechtzeitig gegen ein Blockieren der Hinterräder vorzugehen.If a front axle brake circuit failure is detected, braking systems with electronic brake force distribution must be prevented from underbraking. When driving straight ahead, it is advisable to adapt the rear axle brake pressure to the uncontrolled brake pressure using a rapid pressure build-up grid. Thanks to the pulsed build-up of pressure, an anti-lock braking system in the brake system has the option of taking action to block the rear wheels in good time.
Bei Kurvenfahrt kann der Bremsdruck sofort ungepulste aufgebaut werden. Das heißt, daß ein sofortiger Ausstieg aus der elektronischen Bremskraftverteilung erfolgen kann. Dies beruht auf der Überlegung, daß bei einer Fahrzeugverzögerung, die auch durch den Hinterachs-Bremskreis allein erzielt werden kann, höchstens ein Bremsdruck von etwa 30 bar herrscht, sofern der Vorderachs-Bremskreis doch nicht defekt ist. Wird aber in solchen Druckbereichen irrtümlich ein plötzlicher Druckaufbau an der Hinterachse vorgenommen, so sind trotzdem keine Fahrzeuginstabilitäten zu erwarten aufgrund des niedrigen Bremsdruckes.When cornering, the brake pressure can be built up immediately. This means that an immediate exit from the electronic brake force distribution can take place. This is based on the consideration that in the event of a vehicle deceleration, which can also be achieved by the rear axle brake circuit alone, with a maximum brake pressure of around 30 bar, provided the front axle brake circuit is not defective. If, however, a sudden pressure build-up on the rear axle is erroneously carried out in such pressure ranges, no vehicle instabilities are to be expected due to the low brake pressure.
Im folgenden wird die Erfindung näher erläutert anhand der Schilderung von zwei Situationen, von denen sich eine auf eine Geradeausfahrt und eine auf eine Kurvenfahrt bezieht.The invention is explained in more detail below with the aid of the description of two situations, one of which relates to straight-ahead driving and one to cornering.
Die erste Situation ist folgende: Das Fahrzeug befindet sich bei einer Geradeausfahrt und wird gerade einer pedalbetätigten Bremsung unterzogen, wobei die Schlupfwerte noch nicht so kritisch sind, daß eine Bremsschlupfregelung erforderlich wäre. Sofern sich die Einzelradverzögerung der Vorderräder innerhalb einer bestimmten Bandbreite um die Fahrzeugverzögerung herum bewegen, wird die Schlupfsumme der Hinterräder gebildet. Ist diese Schlupfsumme größer als beispielsweise 1 %, d.h., daß die Hinterachsräder tiefer im Schlupf laufen als die Vorderachsräder, so wird ein Zähler zur Zeiterfassung dieses Zustands gestartet.The first situation is as follows: The vehicle is driving straight ahead and is currently being subjected to pedal-operated braking, the slip values not yet being so critical that brake slip control would be necessary. If the independent wheel deceleration of the front wheels moves within a certain range around the vehicle deceleration, the slip sum of the rear wheels is formed. If this slip sum is greater than 1%, for example, i.e. that the rear axle wheels run deeper in the slip than the front axle wheels, a counter is started to record the time of this state.
Der Zähler wird angehalten bzw. erst gar nicht gestartet, wenn die Fahrzeugverzögerung betragsmäßig 0,5 g überschreitet. Eine solche Fahrzeugverzögerung ist in der Regel nur mit zwei intakten Bremskreisen erzielbar. Der Zähler setzt den Zählvogang erst dann fort, wenn diese Fahrzeugverzögerungsschwelle wieder unterschritten wird.The counter is stopped or not started at all if the amount of vehicle deceleration exceeds 0.5 g. Such a vehicle deceleration can usually only be achieved with two intact brake circuits. The counter only continues counting when this vehicle deceleration threshold is again undershot.
Ab einem bestimmten Zählerstand, d.h. nach Ablauf einer bestimmten Zeit ohne Änderung der SchlupfVerhältnisse, wird ein Vorderachs-Bremskreisausfall angenommen. Wenn zu diesem Zeitpunkt gerade eine elektronische Bremskraftverteilung abläuft, so wird diese in die sogenannte Phase 3 umgeschal- tet, d.h., daß ein schnelles Druckaufbaupulsraster gestartet wird, um den Hinterachsbremsdruck an den ungeregelten Bremsdruck, welcher vom Hauptzylinder kommt, anzupassen. Diese Umschaltung auf Phase 3 ist unabhängig davon, welche Phase der elektronischen Bremskraftverteilung zum Zeitpunkt des Erkennens eines Vorderachs-Bremskreisausfalls gerade stattfindet. Das Druckaufbau-Pulsraster dient dazu, bei hohem Vordruck, also hohem ungeregeltem Bremsdruck einer Einrichtung zur Blockierschutzregelung die Möglichkeit eines rechtzeitigen Eingriffs zu geben, wenn die Hinterräder aufgrund des Bremsdruckaufbaus in hohen Schlupf geraten.From a certain counter reading, ie after a certain time without changing the slip conditions, a front axle brake circuit failure is assumed. If an electronic brake force distribution is currently running, it is switched to phase 3. tet, that is, a quick pressure build-up grid is started in order to adapt the rear axle brake pressure to the uncontrolled brake pressure coming from the master cylinder. This switchover to phase 3 is independent of which phase of the electronic brake force distribution is taking place at the time a front axle brake circuit failure is detected. The pressure build-up pulse grid is used to give a device for anti-lock control the possibility of timely intervention when the back pressure is high due to the build-up of brake pressure at high admission pressure, i.e. high unregulated brake pressure.
Für den Fall, daß an der Vorderachse die Einzelradgeschwindigkeiten sich derart stark und asynchron ändern, daß eine schlechte Wegstrecke angenommen werden muß, so wird das jeweils betroffene Rad bzw. werden die betroffenen Räder von der Betrachtung ausgeschlossen, ob sich die Einzelradverzögerung innerhalb des erwähnten Verzögerungsbandes bewegt.In the event that the individual wheel speeds change so strongly and asynchronously on the front axle that a poor path must be assumed, the wheel or wheels concerned are excluded from consideration of whether the single wheel deceleration is within the mentioned deceleration band emotional.
In der zweiten Situation, bei Kurvenfahrt, sieht die Erkennung eines Vorderachs-Bremskreisausfalls anders aus. Eine Kurvenfahrt kann beispielsweise dadurch erkannt werden, daß die Differenz der Einzelradgeschwindigkeiten zwischen linkem und rechtem Rad jeweils für die Vorderachse und die Hinterachse ermittelt wird. Sind beide Geschwindigkeitsdifferenzen gleichgerichtet und sind beide Geschwindigkeitsdifferenzen beispielsweise größer als ein Schwellenwert von 1 km/h, so kann davon ausgegangen werden, daß gerade eine Kurve durchfahren wird. Aufgrund des Geometrieeinflusses und der Wankbewegung eines Fahrzeuges sind in einem solchen Fall die Kriterien für Geradeausfahrt nicht anwendbar. 1 % Schlupf beispielsweise ist am kurveninneren Hinterrad durch den Geometrieeinfluß oft vorhanden. Radschwingungen am kurveninneren Vorderrad sind aufgrund der Entlastung der kurveninneren Fahrzeugseite auch möglich. Daher werden während einer Kurvenfahrt die Geschwindigkeitsdifferenzen an Vorderachse und Hinterachse miteinander verglichen. Bei Ausfall des Vorderachsbremskreises zeigt sich an der Hinterachse, daß das kurveninnere Hinterrad in höherem Schlupf läuft als die übrigen Fahrzeugräder. Damit ist die Geschwindigkeitsdifferenz der Hinterachse merklich größer als die der Vorderachse. Das Kriterium für das Starten eines Zählers zur Zeiterfassung kann in diesem Fall bei gleichgerichteten Geschwindigkeitsdifferenzen Δvh hinten undIn the second situation, when cornering, the detection of a front axle brake circuit failure looks different. A cornering can be detected, for example, by determining the difference in the individual wheel speeds between the left and right wheels for the front axle and the rear axle. If both speed differences are rectified and if both speed differences are, for example, greater than a threshold value of 1 km / h, it can be assumed that a curve is being driven through. In such a case, the criteria for driving straight ahead are not applicable due to the influence of geometry and the rolling movement of a vehicle. For example, 1% slip is often present on the inside rear wheel due to the influence of geometry. Wheel vibrations on the inside of the front wheel are also possible due to the relief on the inside of the vehicle. Therefore, the speed differences on the front and rear axles are compared with each other when cornering. If the front axle brake circuit fails, it can be seen on the rear axle that the rear wheel on the inside of the curve runs in higher slip than the other vehicle wheels. This means that the speed difference of the rear axle is significantly larger than that of the front axle. In this case, the criterion for starting a counter for time recording can be determined with the same speed differences Δv h behind and
Δvv vorn so aussehen:Δv v front look like this:
ΔVv ΔV, > 0,01 x v RefΔVv ΔV,> 0.01 x v Ref
Allerdings sollte das Starten des Zeitzählers an die Bedingung geknüpft sein, daß das Fahrzeug stärker als mit 0,3 g verzögert wird. Wenn die Fahrzeugverzögerung betragsmäßig 0,3 g übersteigt, so kann auch die Erfüllung des Kriteriums der Geschwindigkeitsdifferenzen nicht als Vorderachs-Bremskreisausfall interpretiert werden, da derart hohe Verzögerungen während einer Kurvenfahrt in der Regel zum Eintritt in die Bremsschlupfregelung führen, wenn ein Bremskreis ausgefallen ist. Wenn sich also die Bremsanlage nicht in einer Bremsschlupfregelung befindet, die Fahrzeugverzögerung aber groß ist, so ist darauf zu schließen, daß der Vorderachs- Bremskreis intakt ist.However, the start of the time counter should be linked to the condition that the vehicle is decelerated more than 0.3 g. If the vehicle deceleration exceeds 0.3 g, the fulfillment of the speed difference criterion cannot be interpreted as a front axle brake circuit failure, since such high delays during cornering usually lead to entry into the brake slip control if a brake circuit has failed. So if the brake system is not in a brake slip control, but the vehicle deceleration is large, it can be concluded that the front axle brake circuit is intact.
Tritt diese Situation während eines Zählvorgangs ein, so wird solange rückwärts gezählt, bis der Zählerstand auf Null steht oder der Betrag der Fahrzeugverzögerung unter die 0,3 g-Schwelle sinkt. In letzterem Fall wird in Folge wieder vorwärts gezählt.If this situation occurs during a counting process, counting continues until the counter reading is at zero or the amount of vehicle deceleration drops below the 0.3 g threshold. In the latter case, the number is increased again in succession.
Bei einem bestimmten Zählerstand des Zeitzählers wird auch während einer Kurvenfahrt ein Vorderachs-Bremskreisausfall angenommen. Sofern gerade eine elektronische Bremskraftverteilung abläuft, muß kein Druckaufbaupulsraster gestartet werden, sondern die elektronische Bremskraftverteilung kann sofort verlassen werden. Der Druck in den Hinterachsbremsen wird also sofort dem ungeregelten Vordruck angepaßt. Dies erhöht den Komfort im Pedalgefühl des Fahrers. Diese Maßnahme ist deshalb unkritisch, weil bei möglicherweise fehlerhaft erkanntem Vorderachs-Bremskreisausfall die kleine Verzögerung, welche Voraussetzung für die Erkennung ist, schon mit einem niedrigen Bremsdruck erzielt werden kann. Dieser liegt bei etwa 30 bar. Wird also fehlerhaft ein Bremskreisausfall erkannt, so ist ein sofortiger Druckaufbau an der Hinterachse unschädlich für das Fahrverhalten, da derart niedrige Bremsdrücke nicht in der Lage sind, die Hinterräder in übermäßigen Schlupf zu bringen.At a certain counter reading of the time counter, a front axle brake circuit failure is also assumed during cornering. If an electronic brake force distribution is currently running, no pressure build-up pulse grid has to be started but the electronic brake force distribution can be left immediately. The pressure in the rear axle brakes is therefore immediately adapted to the unregulated upstream pressure. This increases the comfort in the driver's pedal feel. This measure is not critical, because if the front axle brake circuit failure is detected incorrectly, the small deceleration, which is a prerequisite for the detection, can be achieved with a low brake pressure. This is around 30 bar. If a brake circuit failure is detected incorrectly, an immediate pressure build-up on the rear axle is harmless to the driving behavior, since such low brake pressures are unable to cause the rear wheels to slip excessively.
Neben den Maßnahmen zur Erhöhung der möglichen Fahrzeugverzögerung bei erkanntem Vorderachs-Bremskreisausfall sind selbstverständlich auch Warnanzeigen für den Fahrer vorgesehen, welche ihn über den Defekt der Bremsanlage informieren. In addition to the measures to increase the possible deceleration of the vehicle if a front axle brake circuit failure is detected, there are of course also warning displays for the driver, which inform him about the defect in the brake system.
Claims
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| EP97930446A EP0910527A1 (en) | 1996-07-12 | 1997-06-30 | Double circuit braking system equipped with a device for recognising a front axle braking system breakdown |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19628217.9 | 1996-07-12 | ||
| DE1996128217 DE19628217B4 (en) | 1996-07-12 | 1996-07-12 | Dual-circuit brake system with a device for detecting a front-axle brake circuit failure |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO1998002339A1 true WO1998002339A1 (en) | 1998-01-22 |
Family
ID=7799709
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/EP1997/003403 Ceased WO1998002339A1 (en) | 1996-07-12 | 1997-06-30 | Double circuit braking system equipped with a device for recognising a front axle braking system breakdown |
Country Status (3)
| Country | Link |
|---|---|
| EP (1) | EP0910527A1 (en) |
| DE (1) | DE19628217B4 (en) |
| WO (1) | WO1998002339A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102006029349A1 (en) * | 2006-06-27 | 2008-01-03 | Continental Teves Ag & Co. Ohg | Method for improving an ABS control |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19638280B4 (en) * | 1996-09-19 | 2008-04-03 | Robert Bosch Gmbh | Method and device for generating an error signal in a motor vehicle |
| US6167354A (en) * | 1998-10-19 | 2000-12-26 | Alliedsignal Truck Brake Systems Company | Method and apparatus for monitoring brake operation in an anti-lock or electronic braking system |
| JP3872242B2 (en) * | 1999-09-21 | 2007-01-24 | トヨタ自動車株式会社 | Brake control device |
| US20060043790A1 (en) | 2004-08-27 | 2006-03-02 | Spieker Arnold H | Method for detecting brake circuit failure |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2523055A1 (en) * | 1982-03-08 | 1983-09-16 | Honda Motor Co Ltd | ANTI-LOCK BRAKING SYSTEM COMPRISING SEPARATE SAFETY DEVICES FOR FRONT WHEELS AND REAR WHEELS |
| DE3813316A1 (en) * | 1987-04-21 | 1988-11-10 | Toyota Motor Co Ltd | Hydraulic dual-circuit antilock brake system |
| DE3941409C1 (en) * | 1989-12-15 | 1991-04-18 | Mercedes-Benz Aktiengesellschaft, 7000 Stuttgart, De | Hydraulic dual circuit brake installation for motor vehicle - has electronic control stage for pressure modulator with drive pressure chamber for automatic braking force distribution approaching ideal |
| DE4401995C1 (en) * | 1994-01-25 | 1995-04-06 | Daimler Benz Ag | Brake pressure control device |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4224971A1 (en) * | 1992-07-29 | 1994-02-03 | Teves Gmbh Alfred | Method for increasing the functional reliability of a brake system with electronic control of the brake force distribution |
| DE4309243C2 (en) * | 1993-03-23 | 2003-07-03 | Continental Teves Ag & Co Ohg | Brake system with electronic control of the brake force distribution |
| DE4414980A1 (en) * | 1994-04-29 | 1995-11-02 | Teves Gmbh Alfred | Circuit arrangement for a brake system with EBV |
-
1996
- 1996-07-12 DE DE1996128217 patent/DE19628217B4/en not_active Expired - Fee Related
-
1997
- 1997-06-30 WO PCT/EP1997/003403 patent/WO1998002339A1/en not_active Ceased
- 1997-06-30 EP EP97930446A patent/EP0910527A1/en not_active Ceased
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2523055A1 (en) * | 1982-03-08 | 1983-09-16 | Honda Motor Co Ltd | ANTI-LOCK BRAKING SYSTEM COMPRISING SEPARATE SAFETY DEVICES FOR FRONT WHEELS AND REAR WHEELS |
| DE3813316A1 (en) * | 1987-04-21 | 1988-11-10 | Toyota Motor Co Ltd | Hydraulic dual-circuit antilock brake system |
| DE3941409C1 (en) * | 1989-12-15 | 1991-04-18 | Mercedes-Benz Aktiengesellschaft, 7000 Stuttgart, De | Hydraulic dual circuit brake installation for motor vehicle - has electronic control stage for pressure modulator with drive pressure chamber for automatic braking force distribution approaching ideal |
| DE4401995C1 (en) * | 1994-01-25 | 1995-04-06 | Daimler Benz Ag | Brake pressure control device |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102006029349A1 (en) * | 2006-06-27 | 2008-01-03 | Continental Teves Ag & Co. Ohg | Method for improving an ABS control |
| DE102006029349B4 (en) | 2006-06-27 | 2019-10-17 | Continental Teves Ag & Co. Ohg | Method for improving an ABS control |
Also Published As
| Publication number | Publication date |
|---|---|
| EP0910527A1 (en) | 1999-04-28 |
| DE19628217B4 (en) | 2005-03-03 |
| DE19628217A1 (en) | 1998-01-15 |
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