WO1996016853A1

WO1996016853A1 - Hydraulic brake system

Info

Publication number: WO1996016853A1
Application number: PCT/DE1995/001529
Authority: WO
Inventors: Andreas Wetzel; Jürgen HACHTEL; Thomas Lutz
Original assignee: Robert Bosch Gmbh
Priority date: 1994-11-25
Filing date: 1995-11-04
Publication date: 1996-06-06
Also published as: DE4442032A1

Abstract

Proposed is a purging device (36, 46) for a hydraulic brake system (10) with a pump (21) which pumps hydraulic fluid through a line (22) along which a damping chamber (23) is disposed between two sections (31, 32) of the line. Located in the headspace (30) of the damping chamber (23) is a guide element (36, 46) fitted as a purging device which ensures, by virtue of the special shape of its outlet surface (39, 47), that there are no corners or traps in the headspace (30) in which air bubbles could accummulate. In addition, the outlet surface (39, 47) is precision-machined so that it is particularly smooth, thus ensuring that the air bubbles do not cling to it. These features permit the damping chamber (23) of the brake system to be efficiently purged. The hydraulic brake system (10) described is intended for motor vehicles equipped with an anti-locking system or a traction-control system.

Description

Hydraulic brake systems

State of the art

The invention relates to a hydraulic brake system with an anti-lock device according to the preamble of the main claim. Such a hydraulic brake system is known from DE 4 121 278 AI.

The problem with such hydraulic brake systems is that the system must be completely vented in order to work reliably. This applies all the more as the brake systems are arranged in the course of their lines

Have voids that are difficult to vent. Brake systems of this type often have one or more damper chambers which are connected downstream of one or more pumps. Such damper chambers must be free of trapped air. Therefore, reliable ventilation of the same as well as of the entire brake system is absolutely necessary for a first filling with brake fluid pressure medium as well as for maintenance and repair work.

To facilitate ventilation, DE 40 13 160 AI already suggests arranging the damper chamber with a vertical longitudinal axis in a housing and opening the connected pipe sections on an upper, horizontal chamber wall. In such an arrangement, air pockets can escape purely statically when the damper chamber is filled with pressure medium through an outlet mouth and a line branch adjoining it. Such ventilation is not complete, however, if the damper chamber is installed in the vehicle with a longitudinal axis that deviates from the vertical.

If, in contrast to the above-mentioned venting according to DE 40 13 160 AI, is carried out at a high flow rate, as is the case with the first-mentioned prior art according to DE 4 121 278 AI, a large expenditure on equipment is required, which is usually only the

Vehicle manufacturers can provide for the first filling of the hydraulic brake system.

task

The invention has for its object to improve the ventability, so that the venting can be carried out reliably even in small repair shops without great effort. The venting process should also be able to run purely statically, and it should be precise or feasible even with a slight inclined installation of the damper chamber.

invention

This object is achieved in the hydraulic brake system mentioned at the outset by the characterizing features of the main claim. Advantageous developments of the subject matter of the invention result from the features of the subclaims and from the description. That's the way it is For example, it is advantageous to divide an orifice area adjacent to the through holes into a plurality of partial areas which are inclined to one another in order to ensure ventilation even when the damper chambers are installed or aligned at right angles.

Furthermore, according to another feature of the subclaims, it is advantageous that the guide body is designed as a separate disk and is fixed in the head space of the chamber. Because the end face of the damper chamber can hardly be brought into such a shape and in such a smooth state by simple means as the surface can be formed on a turned disk. Finally, it is particularly advantageous to provide the guide body with a hollow cone mouth surface. Such a design allows the air bubbles to flow safely even when the damper chamber is installed at an angle.

drawing

Two embodiments of the invention are shown in the drawing and explained in more detail in the following description. Show it:

1 shows a circuit diagram of a hydraulic brake system with a damper chamber arranged on the pressure side of a return pump, FIG. 2 shows a cross section through a damper chamber and with a guide body arranged in this damper chamber. 3 shows a view from the inside of the guide body according to FIG. 2, FIG. 4 shows a damper chamber with another guide body, and FIG. 5 shows a view from the inside of the guide body according to FIG. 4. Description of the embodiments

The circuit diagram shown in FIG. 1 represents a multi-circuit hydraulic brake system 10 for a motor vehicle with elements of a

Anti-lock device 11. Brake circuit II, which is assigned to a rear axle of the vehicle, for example, has a brake cylinder 12 and a refill container 13 and wheel brakes 14 and 15

Brake lines 16, 17 and 18. The pressure brakes 19 and 20 for the brake pressure modulation are assigned to the wheel brakes 14 and 15. The anti-lock device 11 also has a pump, for example as a return pump 21, with which, for example, pressure medium removed from the wheel brakes 14 and 15 can be pushed back into the brake line 16. For this purpose, a line 22 is provided on the pressure side of the return pump 21, in the course of which a damper chamber 23 and in the flow direction a throttle point 24 are arranged behind it. These elements of the brake system 10, which lie between the master brake cylinder 12 and the wheel brakes 14 and 15 of the brake circuit II, as well as further, not described parts of the brake circuit II and the brake circuit I of the same design for a front axle are combined in one assembly, hereinafter referred to as the hydraulic unit 25 is designated and which is shown in Figure 1 with a dash-dotted border.

The hydraulic unit 25 has a housing 26 in which the

Damper chamber 23 is provided, as can be seen in Figure 2. For this purpose, a blind bore 27 is made in the housing 26 from below. The damper chamber 23 therefore has a circular cylindrical cross section and one Upper chamber end wall 29 running at right angles to a longitudinal axis 28 of the chamber. The line 22 opens into a head space 30 adjoining the chamber end wall 29, specifically with two line sections, namely an inlet line section 31 and an outlet line section 32. A press-in sleeve 33 is in the outlet line section 32 installed, which carries the throttle point 24. The chamber 23 is closed off from outside air by a tightly inserted cup-shaped closure piece 34 with a snap ring 35 as an axial lock.

A circular guide body 36 bears on the chamber end wall 29 and has two holes 37 and 38 parallel to a longitudinal axis 28. One hole is an inlet hole 37 and forms a continuation of the inlet line section 31 and also has the same diameter as this. Hole 37 lies behind the plane of the drawing. The other hole is an outlet hole 38 and forms the continuation of the outlet line section 32; the hole 38 has a diameter in the size of the outer diameter of the press-in sleeve 33. Both holes 37 and 38 follow one

Muzzle area 39 each a conical extension 44, which can end rounded on the muzzle surface.

The outlet surface 39 is, as also shown in FIG. 3, inclined in such a way that the outlet hole 38 begins at the highest point 40 of the outlet surface 39. The outlet surface 39 consists of a plurality of partial surfaces 41, 42 and 43, of which the two outer partial surfaces 41 and 43 are inclined at an angle of approximately 30 ° and the third partial surface is an intermediate partial surface 42. In contrast to the drawing, it can also have a groove-like design, ie have rounded transitions to the other two partial surfaces 41 and 43. One partial surface 43 is more inclined than the other partial surface 41, and this weakly inclined partial surface 41 should be inclined at least as much with respect to a horizontal one as a possibly required inclined installation of the hydraulic unit 25.

The Leitkδrper 36 is essentially designed as a disc and is inserted in the head space 30 of the damper chamber 23. For safety, in particular with a rough surface of the blind bore 27, it can still be sealed with sealing rings, not shown, or by means of a sealing compound, not shown, against the wall of the damper chamber 23 and against the chamber end wall 29. If rotation of the guide body 36 is to be prevented, the press-in sleeve 33 can either be extended in the exemplary embodiment according to FIGS. 2 and 3 such that it protrudes into the outlet hole 38 of the guide body 36 (shown in broken lines), or it can, as in the case of Embodiment according to Figures 4 and 5, a special eccentrically mounted pin 45 can be provided to prevent rotation. This pin 45 can - as shown - be formed on the Leitkδrper 36, but it can also be carried by the chamber end wall 29.

In the exemplary embodiment according to FIGS. 4 and 5, a guide body 46 is used, in which an orifice surface 47 is formed by a hollow cone. The hollow cone is arranged eccentrically to the guide body 46, and a cone tip lies directly at a highest point 48, at which an outlet hole 49 begins.

An inlet hole 50 opens out further at the

Opening area 47. As can be seen in FIG. 5, pin 45, outlet hole 49 and inlet hole 50 are located for example in a section plane. The remaining features of the exemplary embodiment according to FIGS. 4 and 5 correspond to those according to FIGS. 2 and 3; they therefore have the same reference numbers.

Mode of action

The damper chamber 23 has the upper chamber end wall 29 already mentioned, which is completely covered by the guide body 36 or 46. The Leitkδrper 36 and 46 thus completely separates the problematic upper corner area of the end wall from the system. In addition, the guide body 36 and 46 has a finely machined and therefore smooth mouth surface 39 and 47, on which no air bubbles can get stuck.

If the brake system is now to be vented, brake fluid must be supplied from the master brake cylinder 3, and the vent valves provided in the vicinity of the wheel brakes 14 and 15 must be opened at high points. For bleeding, the return pump 21 is also switched on, which presses the brake fluid through the damper chamber 23.

It is important for the venting success that no air bubbles get stuck in the angled damper chamber 23 or that residual air collects. This avoids the Leitkδrper 36 or 46, which designs the head space 30 of the damper chamber 23 so that at the highest point 40 or 48 of the head space 30 at the outlet hole 38 or 49, the air can flow out completely and unhindered.

With such a construction, air pocket formation is avoided with certainty, and it can Do not collect any air bubbles on the upper chamber end wall 29 and on the guide body 36 or 46. As a result, the damper chamber 23 can be optimally vented. Due to the inventive design of the head space 30 with the streamlined and smooth-walled slope for air bubbles leading to the outlet hole 38 or 49, complete ventilation of the damper chamber 23 and thus the entire brake system can be achieved even at low flow speeds.

Claims

Expectations

1. Hydraulic brake system with one

Anti-lock device and with a pump that conveys pressure medium through a line, in the course of which a chamber of circular cylindrical cross section is provided between two line sections, the two line sections opening into a head space of the chamber, in which a guide body is arranged, characterized in that the guide body (36, 46) is designed as a Füllkδrper, with an inlet hole (37, 50) and an outlet hole (38, 49) and that an underside opening surface (39, 47), which adjoins the two holes (37 , 38; 49, 50) is inclined in such a way that the outlet hole (38, 49) is arranged at the highest point (40, 48) of the orifice surface (39, 47).

2. Hydraulic brake system according to claim 1, characterized in that the two holes (49, 50) lie in one plane with the longitudinal axis (28).

3. Hydraulic brake system according to claim 1 or 2, characterized in that the mouth surface (39) has at least two partial surfaces (40, 42) which are inclined at an angle of substantially 30 ° to each other.

4. Hydraulic brake system according to claim 3, characterized in that the one partial surface (42) is more inclined to a horizontal than the other partial surface (40) and that this inclination is greater than an oblique installation of the damper chamber (23).

5. Hydraulic brake system according to claim 3 or 4, characterized in that an area (partial surface 41) between the two partial surfaces (40, 42) is channel-like.

6. Hydraulic brake system according to claim 3 or 4, characterized in that between the two partial surfaces (40, 42) is an intermediate partial surface (41) which is rectified with the two partial surfaces (40, 42).

7. Hydraulic brake system according to claim 1 or 2, characterized in that the mouth surface (47) is hollow-conical.

8. Hydraulic brake system according to claim 7, characterized in that the hollow cone is arranged eccentrically to the guide body (46) and that the outlet hole (49) begins at the highest point (48) of the hollow cone.

9. Hydraulic brake system according to one of claims 1 to 8, characterized in that the guide body (36, 46) is essentially designed as a disc which in the Head space (30) of the damper chamber (23) is inserted appropriately.

10. Hydraulic brake system according to claim 9, characterized in that the Leitkδrper (46) at an upper

Chamber end wall (29) is fixed by means of an eccentric pin (45).

11. Hydraulic brake system according to one of claims 1 to 10, characterized in that the holes (37, 38) on the

Mouth surface (39) have a conical extension (44).

12. Hydraulic braking system according to claim 11, characterized in that the conical extension (44) on the mouth surface (39) is rounded.

13. Hydraulic brake system according to one of claims 9 to 12, characterized in that the Leitkδrper (36, 46) is sealed with the aid of sealing rings against the wall of the damper chamber (23) and the chamber end wall (29).

14. Hydraulic brake system according to one of claims 9 to 12, characterized in that the Leitkδrper (36, 46) is sealed with the aid of a sealing compound against the wall of the damper chamber (23) and the chamber end wall (29).

15. Hydraulic brake system according to one of claims 1 to 14, characterized in that the outlet hole (38, 49) at least in its mouth region has a larger diameter than the inlet hole (37, 50).