DE102019124372A1 - Expansion tank for a hydraulic brake system of a motor vehicle - Google Patents

Abstract

The invention relates to an expansion tank (10) for a hydraulic brake system of a motor vehicle, comprising a housing (12) with a housing base (14) having at least one connection bore (16) and with a housing base (14) extending from the housing base (14) in the vertical direction of the housing (GH) and a surge rib (24) running perpendicular to the vertical direction of the housing (GH). The invention is characterized in that the expansion tank (10) also has a baffle (26) which, viewed in the vertical direction of the housing (GH), is arranged at a distance from the housing base (14) and extends in the direction perpendicular to the surge rib (24) and covers the connection bore (16). includes.

Description

The invention relates to an expansion tank for a hydraulic brake system of a motor vehicle according to the preamble of the patent claim 1 specified type.

Hydraulic brake systems today have expansion tanks with filling level warning devices that sense the brake fluid level or switch a warning lamp in the cockpit of the motor vehicle when the level falls below a certain level. Due to accelerations acting on the brake fluid, for example caused by cornering, braking, accelerating, slopes, banked bends, or the like, the brake fluid moves to the sides of the expansion tank. In order to make the sensing of the brake fluid level less sensitive to such accelerations, it is known to provide the expansion tanks with vertical surge ribs, that is to say extending in the vertical direction of the tank. Corresponding expansion tanks are sufficiently known from the prior art. The EP 2 566 731 B1 referenced.

• • kein zusätzlicher Druck aufgebaut werden kann und somit die mögliche maximale Verzögerung nicht abrufbar ist
• • aufgrund angesaugter Luft das Bremssystem in den Fehlermodus (Rückfallebene) degradiert wird, was den Kunden u.U. zum Abstellen des Kraftfahrzeugs oder zu einem Werkstattaufenthalt zwingt
• • ein zu geringer Bremsflüssigkeitsstand detektiert wird, obwohl im System eigentlich noch genügend Bremsflüssigkeit vorhanden ist, mit der Konsequenz, dass der Fahrer u.U. in fälschlicher Weise mit einer Warnung „Fehler Bremssystem“ bewarnt wird, was wiederum eine Verunsicherung des Fahrers und damit eine Unfallgefährdung bedeuten könnte.

The vertical surge ribs ensure that the brake fluid moves more slowly in the expansion tank, which counteracts an accumulation of brake fluid on one side of the expansion tank. If, on the other hand, the acceleration is sufficiently long, the situation is the same as without the vertical surge ribs, ie the brake fluid collects on one side of the expansion tank. In the worst case, this can lead to insufficient brake fluid being available in the area of the connection bores via which the brake system is connected to the expansion tank by means of corresponding hydraulic lines to adequately supply the hydraulic brake system and / or to prevent air from entering. The consequence of this can be that

• • no additional pressure can be built up and thus the possible maximum delay cannot be called up
• • The brake system is degraded to the failure mode (fall-back level) due to the sucked in air, which may force the customer to park the motor vehicle or to visit the workshop
• • A brake fluid level that is too low is detected, although there is actually still enough brake fluid in the system, with the consequence that the driver may be incorrectly warned with a warning "Brake system fault", which in turn creates uncertainty for the driver and thus a risk of accident could.

The invention is based on the object of developing an expansion tank according to the type specified in the preamble of claim 1 in such a way that it is more difficult to move the brake fluid to a tank wall even with long acceleration processes and thus the risk of a malfunction of the brake system is reduced.

This object is achieved by the characterizing features of claim 1 in conjunction with the features of the preamble.

The subclaims represent advantageous developments of the invention.

In a known manner, the expansion tank for a hydraulic brake system of a motor vehicle comprises a housing, the housing bottom of which has at least one connection bore for connecting a hydraulic line. Furthermore, the expansion tank comprises a vertically aligned surge rib, that is to say extending from the housing bottom in the vertical direction of the housing, which preferably completely encompasses the housing when viewed in a direction perpendicular to the vertical direction of the housing.

The expansion tank is characterized by the fact that it now also comprises a baffle that is essentially horizontally aligned, that is, when viewed in the vertical direction of the housing, at a distance from the bottom of the housing, extends in the direction perpendicular to the surge rib and covers the connection bore, which preferably completely covers the housing in the longitudinal direction of the surge rib through.

The embodiment according to the invention has the effect that, due to the essentially horizontally aligned baffle covering the connection hole and the associated baffle rib, a complete displacement or flow away of brake fluid from the area of the expansion tank covered by the baffle is prevented, with the result that even with there is a sufficient volume of brake fluid in the area of the connection bore for longer acceleration processes. This advantageously ensures that the braking and suction functions can always be displayed in all driving situations, thus avoiding the risk of insufficient braking power and / or the entry of air into the braking system.

According to a particularly advantageous embodiment, the expansion tank also comprises a level warning device which — extending in the vertical direction of the housing — is designed to penetrate the baffle. Since the If the fill level warning device penetrates the baffle and is thus arranged in the area of the connection bore covered by the baffle, it is advantageously ensured that the disadvantage known from the prior art, namely that a too low brake fluid level is falsely detected, although there is actually still enough brake fluid in the system is present, is avoided. In other words, the risk of the driver becoming unsettled by an incorrect warning is almost eliminated.

Particularly preferably, it is provided that, viewed in the direction perpendicular to the surge rib, the fill level warning device is arranged between the surge rib and the at least one connection bore. Due to the arrangement of the level warning device in the immediate vicinity of the connection bore, namely between the surge rib and the connection bore, a particularly high level of reliability is guaranteed in the detection of the actual brake fluid level in the area under the surge wall.

The transition area from the surge rib to the surge wall is preferably designed without gaps. This means that the surge rib merges directly or without any gaps into the surge wall. The gap-free transition area ensures particularly effective inclusion of brake fluid in the area below the baffle and thus the presence of a sufficiently high volume of brake fluid in the area of the connection bore.

In order to enable a simplified flow of brake fluid into the housing section enclosed by the surge rib and the surge wall, a further particularly advantageous development of the invention provides that the surge wall, starting from the surge rib, viewed in the direction perpendicular to the longitudinal direction of the surge rib, in a gap dimension ( s) ends at a distance from the housing.

wobei mit L die in Richtung senkrecht zur Längsrichtung der Schwallrippe betrachtet maximale Erstreckung Gehäuses bezeichnet ist.According to initial attempts, the following should apply to the gap dimension s: $$0.1\le \text{s / L}\le 0.3$$

where L denotes the maximum extent of the housing, viewed in the direction perpendicular to the longitudinal direction of the surge rib.

A further advantageous embodiment of the invention provides that the baffle is provided with several passage openings. This advantageously enables a further, targeted influencing of the run-on property of the brake fluid.

The surge rib and the surge wall are preferably arranged with respect to one another in such a way that the surge rib and the surge wall enclose an angle α of 80 ° α 100 °.

und
wenn die Länge I der Schwallwand so gewählt ist, dass $$\mathrm{0,2}\le \text{I/L}\le \mathrm{0,6}$$

wobei mit H die in Gehäusehochrichtung GH betrachtet maximale Höhe des Gehäuses und mit L die in Richtung senkrecht zur Längsrichtung der Schwallrippe betrachtet maximale Erstreckung des Gehäuses bezeichnet ist.Obviously, both the distance a between the housing bottom and the underside of the baffle and the length I of the baffle, viewed perpendicular to the longitudinal direction of the baffle rib, have an influence on the possible retention volume. As initial tests have shown, there are particularly advantageous arrangements when
the distance a is chosen so that $$0.25\le \text{Ah}\le 0.5$$

and
if the length I of the baffle is chosen so that $$0.2\le \text{I / L}\le 0.6$$

with H denotes the maximum height of the housing viewed in the vertical direction GH of the housing and L denotes the maximum extension of the housing viewed in the direction perpendicular to the longitudinal direction of the surge rib.

Further advantages and possible applications of the present invention emerge from the following description in conjunction with the exemplary embodiment shown in the drawing.

• 1 eine schematische Schnittdarstellung eines Ausgleichsbehälters nach dem Stand der Technik;
• 2 der Ausgleichsbehälter aus 1 unter der Annahme einer länger einwirkenden Beschleunigungsphase;
• 3 eine schematische Schnittdarstellung eines erfindungsgemäßen Ausgleichsbehälters, und
• 4 der erfindungsgemäße Ausgleichsbehälter aus 3 unter Annahme einer länger einwirkenden Beschleunigungsphase.

In the drawing means:

• 1 a schematic sectional view of a surge tank according to the prior art;
• 2 the expansion tank off 1 assuming a longer acting acceleration phase;
• 3 a schematic sectional view of an expansion tank according to the invention, and
• 4th the expansion tank according to the invention from 3 assuming a longer acting acceleration phase.

1 shows in a schematic sectional view a whole with the reference number 10 designated expansion tank for a hydraulic brake system of a motor vehicle.

The expansion tank 10 includes a housing 12th , its case back 14th three connection holes 16 having. Via the connection holes 16 is the one with brake fluid 18th filled expansion tanks 10 by means of appropriate - not here - Hydraulic lines can be connected to the braking system of the motor vehicle. The brake fluid level in the reservoir 10 is by the dash-dotted line 20th symbolizes.

The expansion tank 10 also includes one in the area of the connection bores 16 arranged with the reference number 22nd labeled level warning device as well as one, from the housing base 14th surge rib extending vertically in the vertical direction of the housing GH 24 .

The maximum housing height, viewed in the vertical direction of the housing GH, is H and that perpendicular to the longitudinal direction of the surge fin 24 considered maximum extension of the housing 12th is denoted by L.

Now lies, as in 2 shown, a longer lasting, here to the left acceleration, this leads to the fact that the brake fluid due to the inertia 18th moves in the opposite direction - here to the right. In extreme cases, this can lead to - as in 2 shown - above the connection holes 16 no brake fluid 18th more is available, with the result that no additional pressure can be built up in the brake system and thus the maximum deceleration cannot be represented and that air is sucked in, which can lead to the brake system being degraded to the failure mode (fall-back level), and may force the driver to park the vehicle or to visit the workshop.

• Erfindungsgemäß umfasst der Ausgleichsbehälter 10 eine zusätzliche Schwallwand 26, die - wie 3 zeigt - in Gehäusehochrichtung GH betrachtet im Abstand a beabstandet zum Gehäuseboden 14 angeordnet und sich in Richtung senkrecht zur Schwallrippe 24, die Anschlussbohrungen 16 vollständig überdeckend, erstreckend ausgebildet ist. Die Länge der Schwallwand 26 ist mit dem Bezugszeichen I und das Spaltmaß zwischen Gehäuse 12 und Schwallwand 26 ist mit dem Bezugszeichen s bezeichnet.

This is where the invention comes in:

• According to the invention, the expansion tank comprises 10 an additional baffle 26th who - like 3 shows - viewed in the vertical direction of the housing GH at a distance a from the housing base 14th arranged and in the direction perpendicular to the surge rib 24 , the connection holes 16 is designed to cover completely, extending. The length of the baffle 26th is with the reference symbol I and the gap between the housing 12th and baffle 26th is denoted by the reference symbol s.

Due to the configuration according to the invention, it is now ensured in an advantageous manner that even in the case of a prolonged acceleration process, cf. 4th , due to the baffle 26th and the surge rib 24 in the area of the connection bores 16 sufficient brake fluid 18th is available so that the braking and suction functions are enabled. In other words, the configuration according to the invention prevents air from getting into the system and increases the availability of the brake system.

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• EP 2566731 B1 [0002]

Claims (10)

Expansion tank (10) for a hydraulic brake system of a motor vehicle, comprising a housing (12) with a housing base (14) having at least one connection bore (16) and with a housing base (14) extending in the vertical direction of the housing (GH) and perpendicular to the vertical direction of the housing (GH) extending surge rib (24), characterized by a surge wall (26) which, viewed in the vertical direction of the housing (GH), is arranged at a distance from the housing base (14) and extends in the direction perpendicular to the surge rib (24) and covers the connection bore (16). Expansion tank (10) Claim 1 , wherein the expansion tank (10) comprises a level warning device (22), characterized in that the level warning device (22) extends in the vertical direction of the housing (GH) and is designed to penetrate the baffle (26). Expansion tank (10) Claim 2 , characterized in that, viewed in the direction perpendicular to the surge rib (24), the fill level warning device (22) is arranged between the surge rib (24) and the at least one connection bore (16). Expansion tank (10) according to one of the preceding claims, characterized in that the surge rib (24) has a transition region in which the surge rib (24) merges into the surge wall (26), the transition region being free of gaps. Compensating tank (10) according to one of the preceding claims, characterized in that the surge wall (26), starting from the surge rib (24) in the direction perpendicular to the longitudinal direction of the surge rib (24), ends at a gap (s) spaced from the housing (12) . Expansion tank (10) Claim 5 , the housing (12) having a maximum extension (L), viewed in the direction perpendicular to the longitudinal direction of the surge rib (24), characterized in that, based on the maximum extension (L) for the gap dimension (s), the following applies: $$0.1\le \mathrm{I.}\text{/ L}\le \mathrm{0.3.}$$

Compensating tank (10) according to one of the preceding claims, characterized in that a plurality of passage openings are made in the surge wall (26). Compensating tank (10) according to one of the preceding claims, characterized in that the surge rib (24) and the surge wall (26) enclose an angle (a) of 80 ° ≤ α ≤ 100 °. Expansion tank (10) according to one of the preceding claims, the housing (12) having a maximum height (H) viewed in the vertical direction of the housing (GH) and the baffle (26) at a distance (a) from the housing base (14), characterized in that In relation to the maximum height (H) for the distance (a) between the housing base (14) and the baffle (22), the following applies: $$0.25\le \text{Ah}\le \mathrm{0.5.}$$

Expansion tank (10) according to one of the preceding claims, wherein, viewed in the direction perpendicular to the longitudinal direction of the surge rib (24), the housing (12) has a maximum extent (L) and the surge wall (26) has a length (I), characterized in that that in relation to the maximum extension (L) for the length (I) of the baffle wall (26) applies: $$0.2\le \text{I / L}\le \mathrm{0.6.}$$

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