Hydraulic unit for traction-controlled motor vehicle brake systems

An electromagnetically actuated valve of a hydraulic unit is received in pressure-tight fashion and mounted without complicated adjustment of the valve stroke. The valve comprises a hydraulic part and an electrical part. The hydraulic part is a pre-mounted unit with a stroke of a seat valve set before insertion into a receiving bore of a metal valve block. The hydraulic part is received in pressure-tight fashion in the valve block by a first swaged connection located between an inlet conduit and an outlet conduit of the receiving bore. A sealing ring that closes off the receiving bore is retained by a radially extending flange of a bushing slipped onto the hydraulic part. The flange is secured to the valve block by a second swaged connection. The hydraulic unit is usable for traction-controlled motor vehicle brake systems.

BACKGROUND OF THE INVENTION 
The invention is based on a hydraulic unit for slip-controlled motor 
vehicle brake systems. 
One such hydraulic unit is already known (DE 42 02 389 A1), in which the 
electromagnetically actuated valve is mounted in the valve block as a 
subassembly comprising a hydraulic and an electric part. The valve block 
has a deep, sharply stepped receiving bore, into whose bottom, 
small-diameter portion an inlet conduit and an outlet conduit open out. 
The hydraulic part of the valve, forming a pre-mounted unit engaging this 
portion of the bore, has two sealing rings on the circumference of its 
sleeve that receives a valve body, a magnet armature and a magnet core; of 
the sealing rings, one is disposed between the conduits and the other is 
disposed toward the boundary plane of the valve block and is axially 
supported by the electrical part of the valve. For that purpose, the 
electrical part engages a large-diameter portion of the receiving bore, on 
the side toward the boundary plane, and is retained in this bore by a 
positive connection by means of a retaining ring press-fitted into an 
undercut of the bore. In this known embodiment, the pressure fluid forces 
acting on the hydraulic part must be absorbed by the electrical portion 
and transmitted to the valve block by the positive connection. The 
electrical part is therefore exposed to relatively major forces. Moreover, 
the embodiment of this connection is expensive and requires a large amount 
of space. 
A space-saving way that is more favorable in terms of force dissipation to 
fasten an electromagnet valve and a valve block of a hydraulic unit for 
traction-controlled brake systems is known from DE-40 30 571 A1. There, 
the valve comprises a hydraulic part and an electrical part mounted on it. 
The hydraulic part is not a premounted unit. Instead, it is made up of 
individual parts installed on the valve block; that is, first a valve body 
with a valve seat is inserted into a stepped receiving bore and secured by 
means of a swaged connection. A guide disk for a valve needle is inserted 
into the bore after that and secured. Near the boundary plane of the valve 
block, a bushing is then inserted into the receiving bore. The bushing 
serves to receive a valve sleeve, widened in funnellike fashion on its 
end, which receives a magnet armature and a magnet core. The valve sleeve 
is secured in the valve block by a swaged connection, in which material 
positively displaced from the edge of the receiving bore covers the 
funnellike sleeve portion supported by the bushing. This swaged connection 
is heavily loaded hydraulically and requires absolute tightness. It can 
therefore be achieved only in a valve block made of steel (see DE 38 10 
581 A1). Adjusting the valve stroke is made substantially more difficult 
in this embodiment, however, because the valve stroke is to a great extent 
dependent on the tolerances of the aforementioned individual parts of the 
hydraulic part, the tolerances of the receiving bore, and the quality of 
the swaged connections. Defects in the hydraulic part of the valve that 
occur after the swaged connections have been made are no longer 
repairable. 
ADVANTAGES OF THE INVENTION 
The hydraulic unit according to the invention has the advantage over the 
prior art that securing of the hydraulic part is done by means of the 
first swaged connection in a region remote from the mouth of the receiving 
bore, which reduces the demands made on the material of the valve block 
and on the swaged connection, so that instead of steel, ductile light 
metal, for instance, can also be used. Sealing off of the receiving bore 
from the outside is now done instead by the sealing ring, placed against 
the boundary plane of the valve block. The load on it by hydraulic forces 
is advantageously absorbed by the flange secured to the second swaged 
connection. One quite essential advantage, however, is the use of the 
hydraulic part as a premounted unit, because it is not subject to any 
alteration of the preset valve stroke in the course of the joining process 
in the valve block, which can also be done in only a few work steps. The 
hydraulic unit can thus be made economically and with high quality. 
By means of the provisions recited, advantageous further developments of 
and improvements to the hydraulic unit recited herein are possible. 
An especially advantageous provision is the inclusion of the sleeve of the 
hydraulic part in the first swaged connection, in that the sleeve is 
surrounded in the annular groove by displaced material of the valve block 
and is pressed intimately against the valve body. The load-bearing 
capacity of the sleeve for hydraulic forces is increased considerably 
thereby. Moreover, sealing of the hydraulic part between the sleeve and 
the valve body is improved.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS 
An electromagnetically actuated valve 10 shown in FIG. 1 is disposed on a 
valve block 11 and forms part of a hydraulic unit 12, not otherwise shown, 
for traction-controlled brake systems in motor vehicles. The valve 10 
comprises a hydraulic part 13 and an electrical part 14. The hydraulic 
part 13 is substantially received and secured in a stepped receiving bore 
15 of the valve block 11, which is of a ductile aluminum alloy. In the 
extension of the receiving bore 15, the hydraulic part 13 protrudes with a 
valve dome 16 beyond a boundary plane 17 of the valve block 11. The 
electrical part 14 is mounted on the valve dome 16. 
The hydraulic part 13 has a thin-walled, tubular sleeve 19 of 
circular-annular cross section. Beginning at the receiving bore 15, the 
sleeve 19 receives a valve body 20 with a press fit. The valve body 20 has 
a valve seat 21 for a closing member 22 of a magnet armature 23 that is 
longitudinally movable in the sleeve 19. On the end remote from the valve 
body 20, the sleeve 19 is closed off by a magnet core 24, as part of the 
valve dome 16. Leaving an air gap 25 from the magnet armature 23, the 
magnet core 24 engages the sleeve 19 with a press fit and is joined to it 
by a weld seam 26 extending around it. This connection is pressure tight. 
A closing spring 27 engaging the magnet core 24 is received in the magnet 
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: the valve 10 is 
thus closed when the electromagnet is without current. 
The hydraulic part 13 is a premounted unit with a stroke of the seat valve 
28, formed by the valve seat 21 and the closing member 22, that is set 
before insertion into the receiving bore 15. This seat valve communicates 
on the one hand with an inlet conduit 29 and on the other with an outlet 
conduit 30 in the portion of the receiving bore 15 remote from the mouth. 
The hydraulic part 13 is received in pressure-tight fashion in the valve 
block 11 by a first swaged connection 31 located between the inlet conduit 
29 and the outlet conduit 30. This swaged connection, which represents a 
positive engagement with the valve block 11, is described hereinafter in 
conjunction with other exemplary embodiments. 
From the direction of the valve dome 16, a filter sleeve 34 associated with 
the inlet conduit 29, a sealing ring 35, and a support ring 36 are slipped 
onto the sleeve 19 of the hydraulic part 13. The receiving bore 15 is 
sealed off in pressure-tight fashion from the boundary plane 17 by the 
sealing ring 35 surrounding the hydraulic part 13. To that end, a bushing 
37 is slipped from the valve dome 16 onto the hydraulic part 13 of the 
valve 10; its relatively thick tube wall 38 surrounds the sleeve 19 with 
slight radial play in the region of the magnet armature 23. On its side 
toward the support ring 36, the bushing 37 has a radially extending flange 
39. This flange 39 is supported in the receiving bore 15 on a bore step 40 
and is joined to the valve block 11 by a second swaged connection 41. This 
second swaged connection 41 is attained by caulking of deforming the edge 
toward the mouth of the receiving bore 15, at which displaced material of 
the valve block 11, taking the form of a bead 42, covers the flange 39 
toward the mouth. This positively engaged connection is capable of 
absorbing hydraulic forces bearing on the sealing ring 35 and diverting 
them to the valve block 11. 
The electrical part 14 of the valve 10 is mounted, after the bushing 37 is 
secured in the valve block 11, onto the valve dome 16 in the region of the 
magnetically active elements, the magnet armature 23 and the magnet core 
24. The electrical part 14 has an electrical coil 45, which surrounds the 
valve dome 16 essentially toward the magnet core. The coil 15 is engaged 
on the outside by a housing 46 of soft magnetic material, into which an 
annular disk 47, likewise of soft magnetic material, is press-fitted at 
the bottom. On the face end of the housing 46 remote from the boundary 
plane 17, connection pins 48 of the coil 45 are formed. The housing 46 of 
the electrical part 14, preferably without play, surrounds the magnet core 
24 on the one hand and on the other, with its annular disk 47 surrounds, 
the tube wall 38 toward the magnet armature of the bushing 37. On 
excitation of the electrical coil 45, the bushing 37, like the magnet core 
24, the housing 46, and the annular disk 47, helps conduct the magnetic 
flux to the magnet armature 23 of the hydraulic part 13. The magnetically 
operative magnet core 24 shifts the magnet armature 23 to the open 
position of the valve 10. 
The first swaged connection 31 serving to secure the hydraulic part 13 of 
the valve 10 in the valve block 11 is embodied as follows (see FIG. 2): 
the valve body 20 of the seat valve 28 takes the form of a straight 
circular cylinder. With the predominant portion of its length, it is 
received with a press fit in the sleeve 19 of the hydraulic part 13. The 
valve body 20, in its middle portion, has an annular groove 51 of 
triangular cross section. The terminal portion 52 of the sleeve 19 is 
pressed, along the entire groove circumference, against the groove wall 53 
of the annular groove toward the magnet armature by crimping. The portion 
of the valve body 20 not encompassed by the sleeve 19 engages, with slight 
play, a portion 54 of the receiving bore 15 toward the outlet conduit. 
This portion 54 of the bore terminates at an encompassing edge 55 of the 
receiving bore 15. After that, the receiving bore 15 widens to an extent 
that slightly exceeds the outer diameter of the sleeve 19. In its further 
course, the receiving bore 15 is widened toward the boundary plane 17 to a 
portion 57 of relatively large diameter, forming a bore step 56. This 
portion 57 provides space for a deforming tool 58 that surrounds the 
hydraulic part 13 with slight play; of this tool, only the portion toward 
the bore is shown in FIGS. 2-5. 
The encompassing edge 55 of the receiving bore 15 forms a stop that limits 
the insertion depth of the hydraulic part 13 in the valve block 11; the 
portion 52 of the sleeve 19 is crimped into the annular groove 51 and 
engages this stop before the first swaged connection 31 is made. This 
swaged connection 31 is made by lowering the deforming tool 58, in such a 
way that after striking the bore step 56 that greatly widens the receiving 
bore 15, the tool displaces material of the valve block 11 into the 
annular groove 51. As FIG. 3 clearly shows, the displaced material fills 
up the annular groove 51, and along with the positive engagement attained 
by the crimping of the sleeve portion 52 it also brings about a 
nonpositive engagement between the sleeve 19 and the valve body 20, which 
reinforces the tightness and strength of the first swaged connection 31. 
After the first swaged connection 31 is made, the deforming tool 58 
releases the hydraulic part 13 of the valve 10, so that the mounting of 
the individual parts, mentioned above, of the valve in the receiving bore 
15 can be done. 
In a departure from this embodiment of the first swaged connection 31, the 
sleeve 19 may be lengthened axially beyond the annular groove 51. In that 
case, a positive engagement of the sleeve 19 with the valve body 20 is 
attainable by beading in of the sleeve into the annular groove 51. As a 
result, the sleeve 19 is pressed positively against both walls of the 
annular groove 51. If the encompassing edge 55 is to be used as a stop, 
then in this embodiment the portion of the valve body 20 after the annular 
groove 51, toward the magnet armature, must be embodied smaller in 
diameter, as is shown for the exemplary embodiment of FIG. 4. 
The exemplary embodiment shown in FIG. 4 is distinguished in that the 
sleeve 19 terminates on its face end at a distance before the annular 
groove 51 of the valve body 20. The valve body 20 is provided after the 
annular groove 51 with a shoulder 59 that reduces its diameter. As a 
result, it is attained that the wall 53 of the annular groove 51 toward 
the sleeve and having the larger diameter, before the first swaged 
connection 31 is made, engages a stop formed by the encompassing edge 55 
of the receiving bore 15 and limiting the insertion depth of the hydraulic 
part 13 into the valve block 11, as is suggested by a dot-dashed line in 
the region of the annular groove, as in FIG. 2. FIG. 4 shows the status 
after the deforming operation has been concluded, by means of which 
material of the valve block 11 has been displaced into the annular groove 
51 located in the region of the shoulder 56 of the valve body 20. 
The exemplary embodiment of FIG. 5 shows the status before the caulking 
operation. Here, as in the exemplary embodiment of FIG. 4, the valve body 
20 is provided with a diameter-reducing shoulder 59. The annular groove 51 
is again located in the region of the shoulder 59. The valve body 20 is 
also nonpositively surrounded by the sleeve 19 over only a portion of its 
length. Between the annular groove 51 and the sleeve 19, the valve body 20 
has an encompassing shoulder 60 that reduces its diameter to the outer 
diameter of the sleeve. The purpose of this shoulder is, when the swaged 
connection 31 is made, to reinforce the flow of material, displaced by the 
shoulder 56 of the receiving bore 15, from the valve block 11 into the 
annular groove 51. 
The foregoing relates to preferred exemplary embodiments of the invention, 
it being understood that other variants and embodiments thereof are 
possible within the spirit and scope of the invention, the latter being 
defined by the appended claims.