GB2397868A

GB2397868A - Electronically actuated valve for use in hydraulic brake systems

Info

Publication number: GB2397868A
Application number: GB0326743A
Authority: GB
Inventors: Holger Schmitt; Thilo Koeder; Massimiliano Ambrosi
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2002-11-19
Filing date: 2003-11-17
Publication date: 2004-08-04
Anticipated expiration: 2023-11-17
Also published as: JP4603789B2; GB2397868B; JP2004169920A; GB0326743D0

Abstract

A valve 10 for use in hydraulic brake systems has a valve body 16 with a longitudinal bore 17, a valve dome 18 connected to the valve body 16, an armature 19 accommodated in the valve dome 18 and movable longitudinally therein, and a tappet 36 for transmitting armature movement to a shut-off member 40 of a valve seat 41. A valve chamber 31 accommodates the shut-off member 40 and filter insert 32, of which a tubular sleeve part (50 figure 3) surrounds valve seat 42. The sleeve part (50 figure 3) prevents circular turbulences in the area of the shut-off member 40 and the valve seat 42 and ensures quick removal of air bubbles thereby reducing noise formation.

Description

r'397868 Electromagnetically actuated valve, in particular for hydraulic

brake systems in motor vehicles

Prior art

The invention is based on an electromagnetically actuated valve according to the type cited in greater detail in the preamble of claim 1.

An electromagnetically actuated valve of this kind is already known from DE 100 36 576 Al, as can be employed for example in an electrobydraulic brake (EHB) as an outlet valve arranged in a hydraulic aggregate downstream a wheel brake cylinder allocated to a vehicle wheel. This valve comprises a valve body to which adjoins an armature chamber in which an armature is guided as longitudinally movable.

The magnetic armature is connected to a tappet which penetrates the valve body and on which a valve shut-off member is constructed, which is arranged in a valve chamber and cooperates with a valve seat constructed on a valve seat part. With this valve, when it is used as an outlet valve of an electrohydraulic brake, there is the problem that if there is a rapid reduction in pressure, i.e. if the brake is quickly released, with inadequate ventilation relatively loud grating and therefore disturbing noises can arise. In order to reduce the noise formation in this respect, the tappet is guided with narrow clearance in the valve body and forms longitudinal channels, separated from one another, between the valve chamber and the armature chamber, so any air present in the valve dome is reduced as quickly as possible by the flow of liquid. However, in this valve in the area of the valve seat and the shut-off member circular turbulences can form, which hold air bubbles trapped in them and therefore can also have a disadvantageous influence on noise formation. The filter insert present here in the valve chamber, which is additionally mounted in the valve body, cannot influence this turbulence formation.

Further known from DE 44 29 211 Al is an electromagnetically actuated valve for slip-regulated hydraulic brake systems in motor vehicles, which with a similar structure on a valve seat part has a sleeve surrounding the valve seat. The sleeve here cooperates with one end of the tappet at least over a limited lifting area to form a throttle, so the electromagnetic valve can adopt the function of a current-regulating valve. In the valve chamber itself no filter element is therein provided for cleaning the flow of pressurising media.

Advantages of the invention The electromagnetically actuated valve according to the invention with the features of claim 1 has by contrast the advantage that with it better flow guidance is performed in the valve chamber, so circular turbulences in the area of the valve seat and the shut-off member are effectively prevented and therefore also air bubbles cannot be held trapped in the turbulence. Overall quicker ventilation is in this way promoted, whereby the tendency of the valve towards noise formation is considerably less. In addition the integration of the filter element and the sleeve part into a single structural element leads to a cost-effective solution, as neither additional parts nor assembly processes become necessary. Furthermore, this measure can easily be combined with previous solutions for muffling noises.

Owing to the measures presented in the subordinate claims advantageous further developments and improvements in the magnetic valve cited in claim 1 are possible, promoting above all a simple, cost-effective and easy-to-assemble method of construction. Further advantageous configurations of the subject of the application emerge from the

description and the drawings.

Drawings An embodiment example of the invention is illustrated in simplified form in the drawings and explained in greater

detail in the following description.

Fig. 1 shows a longitudinal section through an electromagnetically actuated valve.

Fig. 2 shows a cross-section according to II-II in Fig. 1 through a valve body and a tappet of the valve.

Fig. 3 shows as a detail on enlarged scale the area of the valve chamber with the installed filter element.

Fig. 4 shows a perspective illustration of the filter element according to Fig. 1 on enlarged scale.

Description of the embodiment example

An electromagnetically actuated valve 10, illustrated in Fig. 1 of the drawings, for hydraulic brake systems of motor vehicles consists substantially of two modules, namely a hydraulic part 13, mounted in a stepped bore 11 of a valve block 12, and an electrical part 14, placed on top of the hydraulic part.

The hydraulic part 13 has a valve body 16 with a continuous longitudinal bore 17. A valve dome 18 is mounted on the valve body 16 on the side of the electrical part 14. In the valve dome 18 an armature 19 with longitudinally running grooves 20 is accommodated as movable longitudinally.

A valve seat part 22 with a sealing ring 23 arranged on the peripheral side is accommodated in the stepped bore 11 of the valve block 12. This separates a feed bore 24 of the valve block 12 from an outflow bore 25. A filter disc 26 is arranged in the stepped bore 11 on the side of the feed bore 24. The valve seat part 22 provided with a longitudinal bore 27 is connected to the valve body 16 by means of a sleeve 28. The sleeve 28 has a bore 29 on the outer casing side.

The sleeve 28 encloses a valve chamber 31 extending between the valve body 16 and the valve seat part 22. In this valve chamber 31 is accommodated a filter insert 32, which will be entered into in greater detail below. This filter insert 32 still projects very slightly into a bore section 33, with a larger diameter, of the longitudinal bore 17 of the valve body 16. Adjoining this bore section 33 is a I hollow-cone-shaped transition 34 to the part of the longitudinal bore 17 with the smaller diameter.

In the longitudinal bore 17 of the valve body 16 a pin- shaped tappet 36 is accommodated. This tappet 36 extends from the armature 19 into the valve chamber 31. The tappet 36 is guided as movable longitudinally over the entire length of the part of the longitudinal bore 17 with the smaller diameter with a slight radial clearance. The tappet 36 has on the outer casing side four channels 37, separated from one another, extending along the tappet 36, starting from the valve chamber 31, to the valve dome 18 (Figs. 1 and 2). The channels 37 are arranged evenly divided on the tappet 36 and rounded off in concave manner in cross-section. As the tappet 36 projects into the valve chamber 31, owing to the hollow-cone- shaped transition 34 with a contraction 38, which is wedge-shaped in crosssection, to the tappet 36, the valve chamber is connected in a flowpromoting manner to the channels 37 of the tappet.

In the valve chamber 31 facing away from the valve dome is a shut-off member 40 of a seat valve 41. This has a hollow- cone-shaped valve seat 42 constructed on the valve seat part 22 and in liquid-conducting connection with the longitudinal bore 27 of the valve seat part 22. Towards the valve seat part 22 the shut-off member 40 has a cylindrical section 43 with a small diameter, which changes with sharp edges into a conical segment 44 allocated to the valve seat 42. The shut- off member 40 is provided facing away from the valve seat with a cog 45 with which, running on the same axis as the tappet 36, it engages in the latter with large radial clearance.

In the valve chamber 31 is additionally accommodated a re- adjusting spring 47 in the form of a helical compression spring, which acts with bias on the one hand on the valve seat part 22 and on the other hand on the shut-off member 40. Under the action of the re-adjusting spring 47 the shut-off member 40, the tappet 36 and the armature 19 are supported against one another by force-locking. As illustrated in Fig. 1, the seat valve 41 adopts its open position in which via the tappet 36 the shut-off member 40 holds the armature 19 stopped on the valve dome 18.

As Fig. 1 shows in greater detail in connection with the enlarged detail according to Fig. 3 and the perspective illustration according to Fig. 4, the filter insert 32 is constructed as a rotationally shaped part with a U-shaped cross-section. The inner leg of the U-shape therein forms a circular ring-shaped sleeve part 50, while the outer leg is constructed as a ring-shaped filter element 51, the two being rigidly connected to one another by a ring-shaped floor plate 52. The filter insert 32, constructed in one piece, is pressed with its sleeve part 50 on to a cog- shaped prolongation 53 of the valve seat part 22, so the sleeve part 50 encircles the valve seat 42 in the same axis. The sleeve part 50 is therein constructed in the axial direction of such a length that with its freely protruding section 53 it concentrically encircles section 43 of the shut-off member 40, while the open end 54 allocated to the ftnnel- shaped transition projects into bore section 33, with the larger diameter, of the longitudinal bore 17 in the valve body 16. The open end 54 of the sleeve part 50 is constructed in diameter in such a way that it is smaller than the maximum diameter and larger than the minimum diameter of the funnel-shaped transition 34. The filter element 51 has window-like openings 56, constructed between webs 55 and covered by filter cloths 57. The filter element 51 has a freely protruding, ring-shaped edge 58 with which the filter insert 32 is supported on the valve body 16 in the axial direction and which at its outer periphery rests against the sleeve 28 in sealing manner. This guarantees that no liquid can flow through the valve unfiltered. The filter insert 32 is therefore configured in such a way that, additionally to the filter function, it is also used for guiding the flow in the valve. In addition it can be cost- effectively produced as an injection-moulded part and can be easily mounted even in constricted spatial conditions.

The electrical part 14 of the valve 10 substantially encloses the valve body 16, with valve dome 18 and armature 19, projecting out of the valve block 12. The electrical part 14 consists of a coil 60 with an electrical winding 61 enclosed by a housing 62, conducting a magnetic flow, with a yoke ring disc 63. In connection with the electrical part 14 the valve body 16 is at the same time the pole core of the valve 10.

The valve 10 is actuatable by applying current to its electrical winding 61 and therefore generating a magnetic force effect on the armature 19. The magnetic force effects a movement of the armature 19 towards the valve body 16.

The armature movement is transmitted via the tappet 36 to the shut-off member 40. In this way the seat valve 41 can be switched out of the open position in the drawing into the closed position in which the conical segment 44 acts on the valve seat 42 or the seat valve 41 can be transferred by current control into any intermediate positions. When the seat valve 41 is open the feed bore 24 of the valve block 12 is connected to the outflow bore 25. Liquid can therein flow from the feed bore 24 through the longitudinal bore 27 of the valve seat part 22, the valve seat 42, the valve chamber 31, the filter insert 32 and the bore 29 in the sleeve 28 to the outflow bore 25. The valve dome Is is in liquidconducting connection with the liquid-filled valve chamber 31 through the channels 37 of the tappet 36.

On initial filling of the brake system there may be air in the valve dome 18. This air is displaced out of the valve dome 18 in the following way.

When the seat valve 41 opens out of the closed position jets of liquid emerging from the valve seat 42 arrive in the funnel-shaped constriction 38 of the valve chamber 31 opposite the valve seat 42. This flow guidance is further supported by the tubular sleeve part 50 surrounding the valve seat 42. From the funnel-shaped constriction 38 liquid arrives in the valve dome 22 through at least one channel 37 and at least one groove 20 of the armature 19.

There the liquid displaces the air present and pulls it with it through another channel 37 into the valve chamber 31, from which the mixture of liquid and air is removed from the valve 10 through the outflow bore 25.

The filter insert 32 with its special shape is further used by the tubular sleeve part 50 for directed flow guidance.

Freely protruding section 43 of the sleeve part 50 now prevents turbulence being able to be formed in the area of the shut-off member 40 with its pin-shaped section 43.

Section 53 freely protruding from the sleeve part 50 and located concentrically to the valve seat 42, limits the space round the pinshaped shut-off member 40. The flow runs upwards through this space constriction inside the sleeve part 50 and back again outside it. In this way the path of the flow is guided in such a way that no further circular turbulences can be formed. It also prevents air bubbles being held trapped in the turbulence; instead these :.

air bubbles are conveyed through the bore 29 in the sleeve 28 directly to the outside. This flow guidance results overall in the tendency of the valve 10 towards noise formation being considerably less. The sleeve part 50 can therein easily be constructed and arranged in proportion to the funnel-shaped transition 34 in such a way that the two effects can be successfully combined for ventilation.

Naturally alterations to the embodiment example shown are possible without deviating from the concept of the invention.

Claims

Claims 1. Electromagnetically actuated valve, in particular for hydraulic

brake systems in motor vehicles, with a valve body (16) and, connected to the valve body (16), a valve dome (18), in which a magnetic armature (19) is accommodated as movable longitudinally, with a longitudinal bore (17) in the valve body (16) and a tappet (36) guided as movable longitudinally in the longitudinal bore (17) for transmitting an armature movement to a shut-off member (40) of a seat valve (41) in a valve chamber (31) located facing away from the valve dome (18), to which chamber liquid flowing out of a valve seat (42) of the seat valve (41) can be fed and directed through at least one channel (37) of the tappet (36) into the valve dome (18) and with a filter insert (32), allocated to the valve chamber (31) and arranged as fixed to the housing and the filter element (51) of which is switched between the valve seat (42) and a pressurizing medium outlet (25), characterized in that the filter insert (32) has a circular cylindrical sleeve part (50) located inside the filter element (51), surrounding the valve seat (42) and arranged on the same axis as the valve seat (42) in such a way that it projects with its freely protruding section (53) into the valve chamber (31).
2. Valve according to claim 1, characterized in that the filter insert (32) has a substantially U-shaped cross section, the inner leg of which forms the circular ring-shaped sleeve part (52) and the outer leg of which forms the ring-shaped filter element (51), these legs being rigidly connected to one another by a ring shaped floor plate (52).
3. Valve according to claim 1 or 2, characterized in that the filter insert (32) is mounted with its sleeve part (50) as sealed on a valve seat part (22) having the valve seat (42).
4. Valve according to one of claims 2 and 3, characterized in that the filter insert (32) is supported on the valve body (16) with its open, ring shaped edge (58) of the filter element (51).
5. Valve according to claim 4, characterized in that the ring-shaped edge (58) forms a seal between the valve chamber (31) and the pressurizing medium outlet (25).
6. Valve according to one of claims 1 to 5, characterized in that the filter insert (32) is constructed as a one-piece injection moulded part.
7. Valve according to one of claims 1 to 6, characterized in that the sleeve part (50) projects above the valve seat (42) with a section (53), the open axial length of which is larger than the diameter of the valve seat (42).
8. Valve according to one of claims 1 to 7, characterized in that the longitudinal bore (17) guiding the tappet (36) runs into the valve chamber (31) via a funnel-shaped extension (34) and on the one hand the sleeve section (53) is opposite this extension (34), while on the other hand the channels (37) leading along the tappet (36) to the armature chamber are joined to it.
9. Valve according to claim 8, characterized in that the sleeve section (53) ends at an axial distance from the funnel-shaped extension (34).
10. Valve according to one of claims 8 and 9, characterized in that the freely protruding end (54) of the sleeve part (50) has a diameter which is between the maximum and the minimum diameter of the funnel-shaped extension (34).
11. Valve according to one of claims 1 to 10, characterized in that the valve seat part (22) has a cog-shaped prolongation (49) accommodating the valve seat (42) and on which the filter insert (32) is mounted, in particular pressed on.
12. A valve substantially as herein described with reference to the accompanying drawings.