Hydraulic assembly

The present invention relates to a hydraulic assembly for a hydraulic controlling and/or regulating device, including a plurality of hydraulic, mechanical and/or electrically operable functional elements, such as accumulator elements, valve elements, pressure-generating and drive elements which are arranged on an accommodating member, a plurality of pressure fluid channels which interconnect the functional elements and are adapted to provide a hydraulically operable connection between at least one pressure fluid source and a pressure fluid consumer, and a connection to a controlling device for the actuation of the functional elements. A plurality of hollow chambers associated with the functional elements are connected to a joint ventilation system which permits ventilation and bleeding of the hollow chambers for pressure balance with the atmosphere exclusively by way of a point of ventilation which is connected to at least one pressure compensation channel of the ventilation system.

BACKGROUND OF THE INVENTION 
The present invention relates to a hydraulic assembly for a hydraulic 
controlling or regulating device, in particular for slip-controlled 
automotive vehicle brake systems. 
German patent application No. 42 34 013 discloses a hydraulic assembly of 
the type mentioned above. For mounting the hydraulic assembly in 
automotive vehicles, special provisions are necessary to satisfy the 
specifications in terms of operability of the system (for example, a salt 
spray test) and, thus, to satisfy the later daily requirements during 
operation as regards the insusceptibility to salt and spraywater. Special 
corrosion protection arrangements and sealing and ventilation arrangements 
are required to ensure the operability of the assembly which, generally, 
render the assembly more expensive. 
To overcome these conditions, special locations and positions for mounting 
the hydraulic assembly would be desirable. However, such requirements 
cannot always be complied with in view of the complex arrangement of the 
assembly in the entire vehicle compound and the limited mounting space 
available for integration of the systems in an automotive vehicle. 
Therefore, all relevant components of the hydraulic assembly are 
frequently sealed in a sophisticated manner at several locations. Further, 
the individual hollow chambers of the components are separately ventilated 
and bled for pressure balance. A large number of bleeding points 
automatically involves a large number of possible trouble sources which 
may cause malfunctions. Salt or water is likely to accumulate in the valve 
chamber, pump space, engine compartment and pressure accumulator chamber 
and possibly causes flooding of the hollow chambers. 
SUMMARY OF THE INVENTION 
Therefore, an object of the present invention is to provide a hydraulic 
assembly which is protected against corrosion and minimizes cost and 
weight. The assembly should permit ventilation and bleeding irrespective 
of where the entire assembly is positioned, avoiding the application of 
fluid and differential pressure to the individual hollow chambers. 
According to the present invention, this object is achieved by connecting a 
plurality of hollow chambers associated with functional elements to one 
joint ventilation system which permits ventilation and bleeding of the 
hollow chambers for pressure balance in relation to the atmosphere 
exclusively by way of a point of ventilation which is connected to at 
least one pressure compensation channel of the ventilation system. 
If the pressure compensation channel which is connected to the hollow 
chamber of the accumulator element terminates directly into a hollow 
chamber within a cover unit which accommodates the valve elements, and if 
another pressure compensation channel associated with the drive element 
and a pressure generation element terminates into the mentioned hollow 
chamber, and if the point of ventilation is included in the wall of the 
cover unit, especially simple provisions in terms of manufacture are 
achieved for making the two necessary pressure compensation channels in 
the accommodating member. The point of ventilation can be positioned 
relatively easily in a cover unit which is mainly made of plastics. 
A particularly reliable, light-weight and low-cost solution to the problem 
at issue is attained if the point of ventilation has a gas-permeable wall 
portion, which is impermeable to fluids and solid particles, however. 
A breathing diaphragm is appropriate for the point of ventilation. 
According to an alternative, constructive extension, the point of 
ventilation includes a non-return valve which seals the hollow chambers 
against the ingress of moisture. 
If required, a hose is appropriately used for the reliable ventilation and 
bleeding of the hydraulic assembly. The hose is connected to the point of 
ventilation and can be conducted to a moisture-protected area. 
A defined connection of the hollow chamber, remote from the working 
chamber, may be included in the joint ventilation system to the 
atmosphere. A pressure compensation channel extends from the hollow 
chamber of the accumulator element to the hollow chamber of the drive 
element and further until the point of ventilation in the accommodating 
member. 
As another possibility, the point of ventilation can be positioned on the 
frontal end of the accommodating member opposite the drive element, and on 
a cover unit encompassing the valve elements. 
Further objectives, features, advantages and possible applications of the 
present invention can be seen in the following description of two 
embodiments. All features described and/or illustrated per se, or in any 
expedient combination, represent the subject matter of the present 
invention.

DETAILED DESCRIPTION OF THE INVENTION 
FIG. 1 shows a hydraulic assembly including an accommodating member 10, 
shown in cross-section, for the mounting support of the drive element 2, 
the valve elements 3 and the accumulator element 1. The drive element 2 
comprises a direct-current motor having a rotor mounted on a shaft end in 
a bowl-shaped housing and having another bearing which is guided in a 
blind-end bore of the accommodating member 10. This bearing guides the 
shaft of the drive element 2 in the proximity of the shaft eccentric pin 
which has a needle bearing for the actuation of a piston-shaped 
pressure-generating element 4. Another bore portion, reduced in diameter, 
succeeds the point of support of the drive element 2 in the accommodating 
member 10. The bore portion is the point of ventilation 5 which extends 
until the surface of the accommodating member 10. A cover unit 7 which 
encloses the valve elements 3 in a breathing manner is arranged on the 
frontal end of the accommodating member 10. The hollow chamber 3' is 
subdivided for the accommodation of electric or electronic components. The 
accumulator element 1 is movably aligned in the accommodating member 10 in 
a transverse position relative to the drive element 2. The hollow chamber 
1' interposed between the piston-shaped accumulator element 10 and the 
associated closure lid is connected to the hollow chamber 2' of the drive 
element 2 by way of a pressure compensation channel 6. The brush plate of 
the drive element 2 has corresponding apertures which establish an open 
connection between the hollow chamber 1' and the hollow chamber 2'. The 
hollow chamber 2' of the drive element 2 has a pressure-compensating 
connecting conduit in the direction of the eccentric chamber (hollow 
chamber 4'), preferably by way of the clearance fit of the brush plate on 
the drive shaft and the distances between the bearing balls. The point of 
ventilation 5 is adjacent to the hollow chamber 4'. This provides for an 
aperture which connects the hollow chambers in the hydraulic assembly to 
the atmosphere exclusively by way of the point of ventilation 5 existing 
between the accommodating member 10 and the cover unit 7. Possible 
pressure variations in the operation of the hydraulic assembly which make 
the hollow chamber 1' act as an expansion and compression chamber in 
particular due to the movement of the accumulator element 1, are 
transmitted exclusively within a closed ventilation circuit. The flows of 
ventilation generated in the hollow chamber 2' due to rotation are 
subordinate to the pressure variations of the accumulator element 1. Also, 
the flows of air which are caused by piston oscillation of the 
pressure-generating element in the hollow chamber 4' and those caused by 
rotation of the drive element 2 are of little significance in view of 
their uniform course. Aeration and bleeding and, thus, the ventilation in 
the hydraulic assembly, is generally determined by the discontinuous 
operation of the accumulator element 1. In the embodiment shown, the point 
of ventilation is preferably a wall portion 8, which is configured as a 
breathing diaphragm, however, is impermeable to fluids and solid 
particles. This prevents the ingress of contaminants and fluids into the 
area of the accommodating member 10, which is sensitive to moisture and 
dirt, in all operating conditions. 
As an alternative of FIG. 1, however, with an almost identical arrangement 
and construction of the individual functional elements 1, 2, 3, and 4 on 
the accommodating member 10, FIG. 2 shows a variation of the ventilation 
system. In contrast to FIG. 1, a pressure compensation channel 6 from the 
hollow chamber 1' of the accumulator element 1 in FIG. 2 does not 
terminate into the hollow chamber 2' of the drive element 2, but directly 
into the hollow chamber 3' which encompasses the valve elements 3 within 
the cover unit 7. Advantageously, this results in a direct transmission of 
possible pressure pulsations of the accumulator element 1 into the 
relatively large hollow chamber 3' and to the atmosphere through the point 
of ventilation 5 provided in the cover unit 7. Another pressure 
compensation channel 6' in the accommodating member 10 establishes a 
breathing connection to the hollow chamber 4' (eccentric chamber) and to 
the hollow chamber 2' of the drive element 2. Both pressure compensation 
channels 6, 6' consequently terminate irrespective of one another into the 
hollow chamber 3' which is confined by a housing that is in sealing 
abutment on the accommodating member 10 in the embodiment shown. The cover 
unit 7 is not provided as an integral component of the housing in the 
drawing. However, the cover unit 7 primarily has a protective function for 
all electric or electronic elements incorporated in the hollow chamber 3'. 
In the embodiment shown, the point of ventilation 5 accommodates a 
breathing diaphragm which is the gas-permeable wall portion 8 that is 
impermeable to fluids and solid particles. Succeeding the diaphragm is a 
hose 9 (shown as an example) which ensures ventilation and bleeding of the 
hydraulic assembly, protected against fluids and contaminants, 
irrespective of the positioning of the hydraulic assembly vertically to 
the shaft, as shown in the drawing. The result is also one single 
outwardly disposed point of ventilation on the hydraulic assembly so that 
all functional elements on the accommodating member 10 are sealed. The 
description of the embodiment of FIG. 1 is referred to inasfar as not all 
of the details of the embodiment of the hydraulic assembly shown in FIG. 2 
have been described. 
Thus, the advantages of the present invention involve the simplification of 
the previously employed individual sealing and ventilating provisions. 
Accordingly, only one point of ventilation instead of several ventilation 
points is necessary. Also, complicated sealing measures, for example, by 
means of O-rings, are eliminated, when the respective parts permit being 
joined in a metallically seal-tight engagement. In addition, the number of 
components is reduced, testability of the assembly is facilitated and its 
reliability in operation is enhanced. Still further, the hydraulic 
assembly is rendered immersion-proof, and ventilation of the accumulator 
element is improved in particular, with the result that invariably minimal 
hydraulic pressures are ensured after completion of the pressure-reduction 
period when the hydraulic assembly is used on electronically controlled 
brake systems for automotive vehicles.