Fluid handling – Line condition change responsive valves – Direct response valves
Patent
1992-05-07
1994-06-07
Nilson, Robert G.
Fluid handling
Line condition change responsive valves
Direct response valves
251 83, F16K 1518
Patent
active
053180666
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention is related to a solenoid valve for hydraulic brake units with slip control.
In the solenoid valves for hydraulic brake units with slip control for example as shown in German patent application published without examination, U.S. Pat. No. 3,739,915, special pressure limiting valves which are structurally separate from the traction slip control inlet solenoid valves are provided in order to limit the pump pressure to an established maximum value. Indeed, during the traction slip control action, the traction slip control solenoid valves which take the form of isolating valves and are arranged downstream of the master cylinder, are closed. Thus, upon start up of the auxiliary pressure pumps for the purpose of traction slip control action, the brakes of the driven wheels are subjected to the system pressure being monitored by the pressure limiting valves, a return of hydraulic fluid through the pressure limiting valves into the master cylinder being rendered possible only by the admissible pressure of the traction slip control system being exceeded.
The requirement of separate pressure limiting valves lead to an expensive brake unit and has thus proved disadvantageous.
The invention has, therefore, the object to further develop a compact solenoid valve whose number of component parts is minimized by integration of the pressure limiter function.
SUMMARY OF THE INVENTION
According to the invention, this object is achieved by providing an arrangement for countering the electromagnetic actuating force, with a hydraulic actuating force to cause a functionally overlapping valve opening action depending on the system pressure. The solenoid valve according to the invention thus also act as a pressure limiting or relief valve.
The magnetic armature for the solenoid valve may be provided with a stepped, coaxial bore having one section for the accommodation of a spring element the spring element having one end engaging a valve needle. The bore has another section slidably guiding the valve needle for movement relative to the magnetic armature.
This arrangement allows pressure responsive control of the valve needle independently of the control caused by energization of the electromagnetic solenoid.
The valve needle may be formed with a stop which is abuttable against the step of the bore, the stop preferably in the shape of a stop disc which is fit to the one section of the bore in the magnetic armature. The stop disc is furnished with a central stud for locating the one end of the spring element.
In order to make the spring element act on the stop of the valve needle with a defined prestressing force, an axially adjustable thrust member may be inserted into the bore of the magnetic armature on the side opposite the magnetic armature, allowing adjustment of the compression of the spring element to achieve a desired prestressing force.
The thrust member is preferably formed with a restriction bore to insure a sufficient hydraulic damping of the sliding movement of the valve needle. As a consequence, the hydraulic pressure existing in the valve dome can act on the front surface of the valve needle stop in addition to the spring prestressing force, and as a result, a hydraulic opening force exerted on the valve needle must force out the hydraulic fluid within the bore in the magnetic armature through the restriction bore. The stiffness of the spring and the dimensioning of the restriction bore in the thrust member set the stroke speed of the valve needle during the pressure limiting function.
In order to support and guide the valve needle onto the valve seat, a guide element receiving one end of the valve needle is provided. The guide element has to be positioned as near as possible to the end of the valve needle.
A particularly good radial support of the valve needle within the guide element is provided by a cross sectional shape which extends convergently as well as divergently.
A plurality of through bores which are distributed about the circumference are provided in a flared p
REFERENCES:
patent: 4138165 (1979-02-01), Blomberg
patent: 4548233 (1985-10-01), Wolfges
patent: 4631923 (1986-12-01), Smith
Burgdorf Jochen
Goossens Andre F. L.
Volz Peter
Alfred Teves GmbH
Lewis J. Gordon
Nilson Robert G.
Seitter Robert P.
LandOfFree
Solenoid valve for hydraulic brake units with slip control does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Solenoid valve for hydraulic brake units with slip control, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Solenoid valve for hydraulic brake units with slip control will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-786851