Motors: expansible chamber type – Working member position feedback to motive fluid control – Plural input signal means for single motor valve
Patent
1998-02-02
2000-04-25
Lopez, F. Daniel
Motors: expansible chamber type
Working member position feedback to motive fluid control
Plural input signal means for single motor valve
91376R, F15B 1316
Patent
active
060530901
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a vacuum brake power booster for automotive vehicles, including a booster housing having its interior subdivided by a movable wall into a vacuum chamber and a working chamber; a control housing which carries the movable wall and accommodates a control valve that is operable by an actuating rod and controls a pressure difference acting upon the movable wall; and a solenoid which acts upon the control valve and permits ventilating the working chamber irrespective of the actuating rod.
German patent application No. 43 24 688 discloses a vacuum brake power booster of this type.
An object of the present invention is to improve a vacuum brake power booster, more particularly, with respect to a simple design and low-cost manufacture.
SUMMARY OF THE INVENTION
This object is achieved by a control housing with a main part which is arranged and connected in a guide tube along with a cover part slipped axially onto the main part, wherein the solenoid is mounted in the main part on one axial side and in the cover part on the other axial side, and wherein the cover part includes axially protruding centering segments which elastically deform the main part and center it in a clearance-free manner during the assembly of the control housing. In such two-part control housings, tolerances may cause an eccentric positioning of the points of support with respect to the axis of symmetry of the vacuum brake power booster. Thus, an inclined positioning of the solenoid may occur. This may cause leakage of the control valve and increased wear on the points of support. To ensure improved centering under all tolerance conditions occurring, according to the present invention, the cover part includes axially protruding centering segments which elastically deform the control housing and provide its clearance-free centering during the assembly. This takes place automatically without further action of the fitter so that additional manufacturing costs are avoided. The centering segments themselves are shaped during the manufacture of the cover part also without involving additional costs. In a preferred aspect of the present invention, four centering segments are provided which make catch at the main part from radially inwardly and expand the main part during the assembly.
Because a support of the cover part in relation to the solenoid which is positioned in a circumferential direction is important during operation as well, in another preferred aspect of the present invention, additional axial projections with slip chamfers on the cover part are provided to interact with a radial projection on the main part and determine the mutual angular position in the assembly of the cover part and the main part.
In a preferred aspect of the present invention, the cover part includes in its radially outward fringe area a recess for electric cables to pass through. The recess is laterally defined by two radially projecting arms. The cover part of the present invention can still be improved by spacers which extend from the arms and project axially outwardly until the area of a spring of the system. This prevents the electric cables which extend from the solenoid outwardly from getting jammed between the guide tube of the control housing and the spring or its spring guide plate during operation. A sufficient passage is maintained for the cables even under most unfavorable conditions, such as expanding of the spring, transverse forces generated by deformation of the spring, or in the event of eccentricities.
According to another preferred aspect of the present invention, a cable support for fixing the cables is arranged in the control housing in the radial area between the cover part and the guide tube where the cable passes through the cover part. The cables are guided in a defined position, and wear of the cables due to rubbing on parts of the housing, for example, the spring of the system, is prevented by such an arrangement. Further, relief from tension of the cables at the connecting poin
REFERENCES:
patent: 5040450 (1991-08-01), Jakobi
patent: 5460074 (1995-10-01), Balz et al.
Drott Peter
Kramer Horst
Stohr Frank
ITT Manufacturing Enterprises Inc.
Lopez F. Daniel
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