Hydraulic emergency control for changing hydraulic oil pressure in the hydraulic conical pulley axial adjustment mechanism of a continuously variable transmission for varying the clamping force ratio

US5971876A · kind A · utility

Assignees

• Robert Bosch GmbH · DE
• Van Doorne's Transmissie B.V. · NL

Inventors

• Ewald Spiess · Lambach, DE
• Hans Haecker · Leonberg, DE
• Joachim Luh · Bietigheim-Bissingen, DE
• Peter Baeuerle · Ludwigsburg, DE
• Rine Pelders · Nuland, NL
• Wilhelmus Johannes Maria Van Wijk · Udenhout, NL

Key dates

• Filing date: Nov 4, 1997
• Grant date: Oct 26, 1999
• Expiry date: Nov 4, 2017

Classification

• Technology area (CPC F): Mechanical Engineering; Lighting; Heating
• CPC primary: F16H2061/1268
• WIPO field: Mechanical elements
• WIPO sector: Mechanical engineering

Abstract

A hydraulic emergency control for changing the hydraulic oil pressure in the hydraulic conical pulley axial adjustment mechanism of a continuously variable transmission (10) for varying the clamping force ratio has a pump (20) in an open hydraulic circuit that supplies the respective piston chambers (17, 13) of the secondary and primary axial adjustment mechanisms with hydraulic oil. The primary and secondary oil pressures are regulated by separate oil pressure limiting valves (30, 40). At least one throttle valve (51) is arranged between the pump (20) and the output pipe (92) of the open hydraulic circuit, at a point where the pump volumetric flow can be influenced. The hydraulic emergency control allows a starting transmission ratio to be set in a low range when starting the vehicle, whereas a very small reduction ratio is selected at a high driving speed and at light throttle.