Hydraulic unit for traction-controlled motor vehicle brake systems

The object is to reduce the weight of the hydraulic unit. The hydraulic unit (12) has a metal valve block (11) with at least one stepped receiving bore (15) for the hydraulic portion of an electromagnetically actuated valve (10). The hydraulic portion (13) is provided with a securing flange (30), which is inserted into a step (46) of the receiving bore (15) and is positionally secured by a caulking (48) formed from the metal of the valve block (11). A valve dome (16) protruding beyond the boundary plane (17) of the valve block (11) carries the electric portion (14) of the valve (10). The savings in weight is attained by using light metal, such as an aluminum alloy or the like, for the valve block (11). The hydraulic unit is intended for traction-controlled brake systems of motor vehicles.

BACKGROUND OF THE INVENTION 
The invention is based on a hydraulic unit for traction-controlled brake 
systems of motor vehicles, as generically defined by the preamble to the 
main claim. 
German Patent Application DE 38 10 581 A1 has already disclosed making such 
a hydraulic unit with a valve block from steel, making stepped receiving 
bores for the hydraulic portion of electromagnetically actuated valves in 
the block, providing securing flanges for the valves, introducing the 
flanges into the stepped bores, and caulking the steel material of the 
valve block against the securing flanges in order to positionally secure 
the valves in a pressure-tight manner. DE 38 10 581 A1 expressly points 
out that the caulking process makes it indispensible that only steel be 
used as the material. It says that this makes such hydraulic units heavy 
and makes the caulking expensive and not without problems, especially with 
respect to the sealing. Instead, for a light structure of aluminum, it 
proposes fastening at least one electromagnet valve between two aluminum 
plates by means of tension screws. In the state of the art that is 
discussed in DE 38 10 581 A1 as being disadvantageous, the securing flange 
of the applicable electromagnet valve is made by funnel-like flaring of 
the open end of a capsule-like valve dome which contains magnetically 
operative elements, such as the armature and magnet core. Depending on the 
shape of the securing flange, the counterpart face of the step of the 
receiving bore is embodied expensively. The material of the valve block 
positively displaced by the caulking surrounds the entire circumference of 
the securing flange. Nevertheless, this embossed connection clearly does 
not meet the demands made of it in terms of strength, because German 
Patent Application DE 40 30 571 A1 describes letting a bushing, adapted to 
the shape of the securing flange, into the receiving bore of the valve 
block and providing not only the frictionally engaged fastening of the 
flange attained by the embossed connection but also a positive connection, 
so as to counteract the thrust force acting between the contact faces of 
the aforementioned elements. However, this makes it more expensive to 
secure the hydraulic part of the electromagnet valve in the valve block. 
In electromagnetically actuated valves for brake systems of the type 
described at the outset, known from German Patent Application DE 41 42 004 
A1, the valve dome has a radially protruding securing flange, which is 
retained in sealed fashion in a valve block by means of a screw sleeve 
slipped onto the valve dome. Securing in this way, by means of the screwed 
sleeve and an insertion thread disposed for it in the valve block, is 
expensive. Moreover, such insertion threads are harder to clean than 
smooth stepwise recessing of the diameter of bores. Yet careful cleaning 
is indispensible, because unremoved chips cause leakage between the 
securing flange and the valve block or can get into the hydraulic circuit, 
which can result in severe damage or loss of function of the hydraulic 
unit. 
ADVANTAGES OF THE INVENTION 
The hydraulic unit according to the invention as defined by the body of the 
main claim has the advantage over the prior art that not only can the at 
least one valve be connected to the valve block in a way that can be 
achieved economically, but also a considerable savings in weight is 
attained because of the choice of material which is substantially lighter 
than steel. 
By the provisions recited in the dependent claims, advantageous further 
features of and improvements to the hydraulic unit defined by the main 
claim are possible. 
With the embodiment defined by claim 2, on the one hand a diversion of 
forces acting upon the hydraulic portion of the valve to the valve block 
is attained in a simple way; on the other, deformation of the valve dome 
is avoided, and the freedom of motion of the elements disposed inside the 
valve dome is reinforced by the shaping of the bushing and by caulking of 
the securing flange, which can be done in an intrinsically arbitrary way. 
The further feature defined by claim 3 is distinguished not only by 
less-complicated production of the receiving bore and securing flange but 
also by a connection between the hydraulic part of the valve and the valve 
block that is predominantly in the form of positive engagement and can 
withstand heavy loads. 
With the improvement of claim 4, because of the material comprising the 
bushing, on the one hand high design strength of the bushing when its 
securing flange is caulked is attained, and on the other, favorable 
conduction of the magnetic flux between the housing of the electrical 
portion and the magnetically operative elements of the hydraulic portion 
of the valve is attained. Hence the bushing has dual utility.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS 
An electromagnetically actuated valve 10 shown as a first exemplary 
embodiment in FIG. 1 is disposed on a valve block 11 and forms a portion 
of a hydraulic unit 12, otherwise not shown, for traction-controlled brake 
systems of motor vehicles. The valve 10 comprises a hydraulic portion 13 
and an electric portion 14. The hydraulic portion 13 is substantially 
received and secured in a stepped receiving bore 15 of the valve block 11, 
which is made from a ductile aluminum alloy. In the extension of the 
receiving bore 15, the hydraulic portion 13, with a valve dome 16, 
protrudes beyond a boundary plane 17 of the valve block 11. The electrical 
portion 14 is mounted on the valve dome 16. 
The hydraulic portion 13 has a thin-walled guide sleeve 19 of 
circular-cylindrical cross section. A valve body 20 is received with a 
press fit in the guide sleeve 19, beginning at the receiving bore 15. The 
valve body 20 has a valve seat 21 for a closing member 22 of an armature 
23 that can be moved longitudinally in the guide sleeve 19. On the end 
remote from the valve body 20, the guide sleeve 19 is closed by a magnet 
core 24 which is part of the valve dome 16. The magnet core 24 engages the 
inside of the guide sleeve 19 with a press fit, leaving an air gap 25 
between it and the armature 23, and is joined to the guide sleeve by a 
weld 26 extending all the way around. This connection is pressure-tight 
and can withstand heavy hydraulic loads. A closing spring 27 engaging the 
magnet core 24 is received in the armature 23 and in the position of 
repose of the valve 10, as shown, keeps the closing member 22 in contact 
with the valve seat 21: Thus the valve 10 is closed when without current. 
A bushing 29 is slipped onto the middle portion of the guide sleeve 19, 
specifically radially outside the magnetically operative armature 23. The 
bushing 29 has a wall thickness greater than that of the guide sleeve 19 
of the valve dome 16. Counter to the valve body 20, the bushing 29 is 
provided with a radially protruding securing flange 30, both end faces 31 
and 32 of which extend at right angles to the axis of the receiving bore 
15, which is at the same time the longitudinal axis of the valve 10. The 
bushing 29 comprises magnetizable material, such as soft-magnetic steel. 
It is firmly joined to the stainless steel guide sleeve 19 by welding 33. 
The welding can be done, as shown, on the face end of the sleeve 29, or it 
may be located in the region of one or more recesses 34, with which the 
wall thickness of the bushing 29 is reduced in the region of the boundary 
plane 17. The welding 33 can encompass either the entire circumference of 
the guide sleeve 19 or only portions thereof. Instead of the welding 33, 
the connection of the bushing 29 to the guide sleeve 19 can also be done 
by adhesive bonding. 
Beginning at the securing flange 30, a support ring 37 and a sealing ring 
38, which tightly seals off the receiving bore 15 from the outside, are 
received on the portion of the guide sleeve 19 toward the receiving bore 
15. The sealing ring 38 is followed by a filter sleeve 39, a second 
sealing ring 40, and a support ring 41. The second sealing ring 40 
separates pressure fluid lines 42 and 43 of the valve block 11, the 
passage through which can be switched with the valve 10. 
The dimensionally rigidly embodied securing flange 30 of the bushing 29 is 
received in a bore step 46 of the receiving bore 15. The original contour 
of the bore step 46 is represented by dot-dashed lines: Thus the diameter 
of the bore step is smaller than the diameter of the electric portion 14 
of the valve 10. The end face 32 toward the valve body of the securing 
flange 30 rests on the bottom of the bore step 46. The other end face 31 
of the securing flange 30 is conversely covered by a bead 47 of material 
which is made by caulking 48 of the material positively displaced from the 
edge of the bore. The region at the bore edge of the step 46 acted upon by 
this embossed connection is also located inside the diameter of the 
electric portion 14. The bead 47 of material engages the entire 
circumference of the securing flange 30 and secures the position of the 
hydraulic portion 13 in the valve block 11. It is capable of reliably 
diverting into the valve block 11 the forces that become operative inside 
and outside the hydraulic portion 13 and are transmitted to the securing 
flange 30. If the stress is not so great, it may suffice for only portions 
of the securing flange 30 to be engaged by portions of the material bead 
47. 
The electric portion 14 of the valve 10, once the hydraulic portion 13 has 
been secured in the valve block 11, is mounted on the valve dome 16 in the 
region of the magnetically operative elements, that is, the armature 33 
and magnet core 24. The electric portion 14 has an electric coil 51, which 
encompasses the valve dome 16 in the region of the magnet core 24. A 
housing 52 of soft-magnetic material fits over the coil 51, and an annular 
disk 53 also of soft-magnetic material is pressed into the bottom of this 
housing. On the face end remote from the boundary plane 17 of the housing 
52, connection pins 54 of the coil 51 are formed. The housing 52 of the 
electric portion 14 fits, preferably without play, over the magnet core 24 
on the one hand and, with its annular disk 53, over the bushing 29 of the 
hydraulic portion 13 on the other. When the electric coil 51 is excited, 
the bushing 29, like the magnet core 24, housing 52 and annular disk 53, 
contributes to conducting the magnetic flux to the armature 23 of the 
hydraulic portion 13. The magnetically operative magnet core 24 shifts the 
armature 23 into the open position of the valve 10. 
In the second exemplary embodiment shown in FIG. 2, the electromagnetically 
actuated valve 10' also has a hydraulic portion 13 and an electric portion 
14. Because of its structural design, the valve 10 is switched to be open 
when without current in its current position of repose. It has a valve 
dome 16 with a thin-walled capsule 57, in which the armature 23 of the 
valve 10' is received in a longitudinally movable manner. The capsule 57 
is joined by welding 26, analogously to the first exemplary embodiment, to 
the magnet core 24, which is elongated to inside the stepped receiving 
bore 15. The magnet core 24 penetrated by a valve tappet 58 has a 
relatively great wall thickness. In the region of the boundary plane 17 of 
the valve block 11, the bushing 29 is thrust, with its securing flange 30 
received in the bore step 46, onto the magnetically operative magnet core 
24. The connection of the bushing 29 to the magnet core 24 is attained by 
an embossed connection, and as a result embossed indentations 59 of the 
bushing engage a groove 60 or recesses of the magnet core 24. The securing 
flange 30 of the hydraulic portion 13 is joined to the valve block 11 by 
caulking 48, as in the first exemplary embodiment. Also in the same way as 
in that embodiment, the electric portion 14 is mounted on the valve dome 
16 of the valve 10. 
If there is a multiple assembly of valves 10 or 10' in the course of the 
boundary plane 11 of the valve block 11, a high packing density is 
attainable, since the caulking 48 is located inside the diameter of the 
electric portion 14. Valves 10 and 10' can therefore be disposed very 
close together.