DE102022204267A1 - Insert for a brake fluid expansion tank and brake fluid expansion tank with this insert - Google Patents

Abstract

The invention relates to an insert (1) for a brake fluid expansion tank (23), designed as a cylindrical sleeve (3), which has two bases (5, 7) on the inside spaced apart in the direction of the cylinder axis, each of the two bases (5, 7) having at least one Has a through hole (9, 11) and in which no through hole (9) of the first base (5) is aligned with a through hole (11) of the second base (7) when viewed in the direction of or parallel to the cylinder axis (Z).

Description

The invention relates to an insert for a brake fluid expansion tank for a hydraulic motor vehicle brake. This insert is used in particular in the filler neck of the brake fluid expansion tank.

Hydraulic vehicle brakes for motor vehicles typically have a brake fluid expansion tank, hereinafter also referred to as a compensation tank. This serves to enable temperature-related expansion or evaporation of a brake fluid and to compensate for the fluctuating volume even in the event of temperature expansion. In order to fulfill this function, the expansion tank must not be hermetically sealed, but rather has a vent, for example in the form of a slot closure, to enable pressure equalization with the environment.

If the road is uneven, brake fluid can be accelerated horizontally in the expansion tank as a result of abrupt changes in speed and can unintentionally escape from the expansion tank through the vent. The same applies if you hit a pothole, as brake fluid is then accelerated vertically.

The DE 10 2010 010 412 B3 describes a brake fluid reservoir with a housing that has a lower housing chamber that is filled with brake fluid and an upper housing chamber that is primarily filled with air. The two housing halves are separated from each other by a partition equipped with a valve. This design is intended, among other things, to prevent foam formation.

One object of an embodiment of the invention is to reduce the amount of brake fluid escaping from the expansion tank, particularly when hitting a pothole while driving.

According to a first aspect of the invention, an insert for a brake fluid expansion tank and preferably for its filler neck is proposed to solve the above-mentioned problem. This insert made of a brake fluid-resistant material, for example a plastic such as polypropylene or polyethylene, is designed as a cylindrical sleeve, the inside of which has two floors spaced apart in the direction of the cylinder axis or two floors arranged along the cylinder axis.

When the sleeve is used as intended or when the sleeve is installed in the expansion tank, the cylinder axis is directed in the direction of an outlet opening of the expansion tank, in particular vertically upwards. The cylinder axis of the sleeve preferably coincides with the axis of symmetry of the filler neck of the expansion tank.

At least one of the two floors, in particular the floor facing the brake fluid level in the expansion tank or the bottom floor in the installed position with the cylinder axis aligned vertically, is designed to be completely closed from the starting point and thus prevents fluid from passing through the sleeve. However, each of the two bases has at least one through hole, with no through hole in the first base aligned with a through hole in the second base when viewed in the direction of or parallel to the cylinder axis. This prevents the brake fluid from shooting directly through both openings towards the outlet opening and getting out into the open when the brake fluid accelerates vertically. This at least reduces unwanted brake fluid loss.

Since the geometry and size of the through holes are not initially important, this unwanted loss of brake fluid is also reduced if the through openings of the first and second bases are only partially aligned with each other or partially overlap when looking in the direction of or parallel to the cylinder axis but complete. However, an arrangement without an overlap is preferred.

The through openings serve to equalize the pressure between an inner area of the expansion tank and the external environment and also allow temperature-related expansion of the brake fluid. When the cylinder axis is aligned along the vertical, they enable a flow of brake fluid from below the lower base through its through hole to the space between the two bases and from there through the through hole of the upper base to the area of the outlet opening.

From the above it can be seen that the above formulation that the two floors should be spaced apart is to be interpreted broadly. In a simple case, the two floors are arranged planar and parallel to each other, so that the distance in the direction of the surface normal is constant. However, arrangements should also be included in which not every point on one floor is spaced from the other floor, for example those in which the floors collide locally and, for example, form a so-called kiss point. To avoid an unwanted brake fluid leak, On the one hand, it must be ensured that brake fluid passing through the first through hole hits the second floor and is deflected, and on the other hand, because of a possible increase in volume and also because of pressure equalization, brake fluid can get from the first through hole to the second through hole and from there flow to the area of the outlet opening can.

In a further embodiment, each of the two floors has exactly one through hole. This simplifies the geometry of the sleeve and thus its production.

In an improvement of the embodiment of the last paragraph, the positions of the two through holes, when projected onto a plane perpendicular to the cylinder axis and based on polar coordinates, have an angular difference between 140 ° and 220 ° in this plane, the polar axis coinciding with the cylinder axis. An angle difference between 165° and 195% is preferred and 180° is particularly preferred. Choosing this angle difference increasingly ensures that the two through holes are quite far apart and also that the speed of the brake fluid from the first through hole to the second through hole is reduced, making accidental fluid loss even less likely.

In a further embodiment, the sleeve is produced using a 3D printing process, in particular to form a sleeve made of plastic. This makes it easier to produce the sleeve with its internal bases and through holes compared to conventional plastic production. At the same time, the use of new tools is avoided.

In a further embodiment, when the cylinder axis is aligned along the vertical, the lower of the two bases has an upward indentation. In this way, a sleeve can also be used if the inner wall of the expansion tank has an unfavorable geometry and parts of it, for example reinforcing ribs, especially in a flat design, protrude into the space to be occupied by the sleeve or with the sleeve would collide.

In a further embodiment, an external thread is provided at one end for the sleeve to be arranged in the filler neck. When the cylinder axis of the sleeve is aligned along the vertical and coaxial to the axis of the filler neck, the external thread is located at the upper end of the sleeve and, relative to its mounting position, at the outside end of the filler neck. A closure, for example a bayonet closure, in particular a closure with a slot closure for pressure equalization, can then be screwed onto the external thread in order to close the expansion tank.

Furthermore, an embodiment is conceivable in which the sleeve has one or more areas projecting from the outer wall, which correspond to recessed areas on the inner wall of the filler neck. This provides anti-twist protection, i.e. it prevents the sleeve from rotating when the closure is screwed onto the external thread.

A further aspect of the invention relates to a brake fluid expansion tank with a filler neck, which has an insert according to one or more of the embodiments explained above and which, thanks to the sleeve, is less prone to brake fluid leaking, particularly during vertical accelerations, for example as a result of potholes.

In one embodiment of the expansion tank, it has a filler neck, in particular a cylindrical filler neck, the inner wall of which has recessed areas which correspond to protruding areas on the outer wall of the sleeve in order to prevent the sleeve from rotating by positive locking. This is particularly advantageous if a removable closure is provided for the expansion tank, which is screwed onto the outer thread of the sleeve.

• 1 einen Einsatz gemäß einer Ausführungsform der Erfindung;
• 2 einen Ausgleichsbehälter für Bremsflüssigkeit mit dem Einsatz;
• 3 einen Blick

The invention will be explained in more detail below using an exemplary embodiment with figures that are not to scale, with the same reference numbers showing the same objects. The exemplary embodiment merely serves to illustrate a possible design, whereby the person skilled in the art will determine that the claimed teaching can also be structurally implemented in a different way. Specifically shows

• 1 an insert according to an embodiment of the invention;
• 2 a brake fluid expansion tank with the insert;
• 3 a glance

1 shows an insert 1 with a cylindrical sleeve 3 with a cylinder axis Z, which in this case should run parallel to the vertical or the z direction. As usual, the vertical runs radially outwards from the center of the earth.

The insert 1 has two full-surface and planar bases 5 and 7 on the inside, which are arranged parallel to one another, with the cylinder axis Z as Surface normals. The lower floor 5 has exactly one through hole 9 and the upper floor has exactly one through hole 11.

There is no axis parallel to the cylinder axis Z that passes through both through holes 9 and 11. Relative to the plane of the base 5 or 7, the centers of the two through holes are offset by Δφ = φ2 - φ1 = 180 ° in polar coordinates with respect to a selected radial ray R. This non-alignment of the two through holes 9 and 11 prevents vertically accelerated brake fluid from passing through both through holes 5, 7 to the area 19 when driving a motor vehicle with a brake fluid expansion tank on uneven roads, in which (the in 1 (not shown) outlet opening of the brake fluid container is located.

2 shows schematically an expansion tank 21 for brake fluid 23. You can also see the insert 1, which is arranged within the filler neck 25, which is also cylindrical. The filler neck 25 is screwed at its upper end to the screw cap 27 using its external thread 13, for which the latter has a corresponding internal thread (not shown). This screw cap 29 also has a slot closure (not shown) to equalize the pressure between the gas area 31 and the outer area 33

Reference symbol list

1

Mission

3

sleeve

5

Ground / first ground

7

Floor / second floor

9

through hole

11

through hole

13

External thread

15

external wall

17

protruding area

19

Area of the outlet opening

21

surge tank

23

brake fluid

25

Filler neck

27

Screw cap

29

Screw cap

31

Gas area

33

recessed area

Z

Cylinder axis

R

Radial beam

QUOTES INCLUDED IN THE DESCRIPTION

This list of 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.

Cited patent literature

• DE 102010010412 B3 [0004]

Claims (10)

Insert (1) for an expansion tank (21) for brake fluid (23), designed as a cylindrical sleeve (3), which has two bases (5, 7) on the inside spaced apart in the direction of the cylinder axis (Z), each of the two bases (5, 7) has at least one through hole (9, 11) and in which no through hole (9) of the first base (5) is aligned with a through hole (11) of the second base (7) when viewed in the direction of or parallel to the cylinder axis (Z). Use after Claim 1 , characterized in that each of the two floors (5, 7) has exactly one through hole (9, 11). Use after Claim 2 , characterized in that the two through holes (9, 11) have an angular difference between 140° and 220° when projected onto a plane perpendicular to the cylinder axis (Z) and based on polar coordinates. Use according to one or more of the preceding claims, produced using a 3D printing process. Use according to one or more of the preceding claims, in which when the cylinder axis (Z) is aligned along the vertical, the lower of the two bases (5) has an upward indentation. Use according to one or more of the preceding claims, in which an external thread (13) is provided for the sleeve (3) at one end. Use according to one or more of the preceding claims, in which the sleeve (3) has areas (17) projecting from its outer wall (15) which correspond to recessed areas (33) on an inner wall of the filler neck (25) in order to form a positive fit To prevent the sleeve (3) from rotating. Brake fluid expansion tank (23) with a filler neck (25), characterized by an insert (1) according to one of Claims 1 until 7 . Brake fluid expansion tank (23). Claim 8 , characterized in that the inner wall of the filler neck (25) has recessed areas (33) which correspond to protruding areas (17) on the outer wall (15) of the sleeve (3) in order to protect the sleeve (3) from twisting by positive locking cause. Brake fluid expansion tank (23). Claim 8 or 9 , characterized in that a screw closure (29) is provided, the screw thread (13) of which can be screwed onto the external thread (13) of the sleeve (3).

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