The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 02, 1986
Filed:
Nov. 30, 1984
Frederick J Adams, Clevedon, GB;
TRW Cam Gears Limited, Hertfordshire, GB;
Abstract
A power assisted steering system and a steering assembly for such a system. The steering assembly has a steering output comprising an arm 6 displaceable through a toothed sector 7 by a racked piston nut 3 drivingly engaging a worm shaft 7 rotatable by a steering input shaft 12. The piston 3 and its cylinder 2 provides a first servomotor for power assisting the steering output. The first servomotor is powered by a first hydraulic system 16 comprising a rotary valve 10 which is responsive to the steering input to control fluid pressure to the first servomotor. The steering system also includes a second hydraulic system 25 comprising an axially responsive spool valve 21 which controls fluid pressure to operate a second servomotor 28 coupled to the steering output arm 6. The rotary and axially responsive valves 10 and 21 are axially coupled together by the shaft 7 which is axially displaceable to control operation of the valve 21. Axial biasing springs 34 and 35 axially spring load the shaft 7 to a neutral condition for the valve 21. During use of the steering assembly the resistance to displacement of the piston 3 by the drive imparted thereto from the worm shaft 7 serves to provide a reaction on the shaft 7 which displaces the shaft against its spring biasing to operate the valve 21 and provide power assistance through the system 25 and ram 28. This power assistance may be effected prior to, simultaneously with or subsequent to power assistance provided by the servomotor comprising the piston 3 powered by operation of the rotary valve and from the hydraulic system 16. If required, both hydraulic systems 16 and 25 can be used to power a single and common servomotor.