Clutch actuator with protection against overload and/or faulty operation

• Main Authors: JOERG PANKOKE, WINFRIED STUERMER, FRANK HIRSCHMANN, JOACHIM LINDNER, BARBARA ESTER, JUERGEN LIEBLER, HANS JURGEN DREXL, THOMAS OTTO
• Format: Patent
• Language: English
• Published: 19.04.2000
• Edition: 7
• Subjects: ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS INVEHICLES; ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OFTRANSMISSIONS IN VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GASEXHAUST OR FUEL SUPPLY OF PROPULSION UNITS, IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; BLASTING; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; BRAKES; CLUTCHES; COUPLINGS FOR TRANSMITTING ROTATION; ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVEFUNCTIONING OF MACHINES OR INSTALLATIONS; HEATING; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; LIGHTING; MECHANICAL ENGINEERING; PERFORMING OPERATIONS; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OFVEHICLES; THERMAL INSULATION IN GENERAL; TRANSPORTING; VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES; VEHICLES IN GENERAL; WEAPONS

A clutch actuator 10, eg for a commercial vehicle, comprises a pneumatic cylinder 14 controlled by a hydraulic valve 42 operated by a master cylinder and clutch pedal arrangement 60, 62, 200a, 62a. If, for example, pneumatic power source 51 fails an overly high pressure may be produced by the master cylinder clutch pedal arrangement 200a, 62a resulting in damage to the actuator 10. This is avoided in one embodiment by providing an expandable linkage, eg four bar chain, 214a, 216a, 218a, 220a which prevents a high pressure from being produced by expanding about pivot point 222a, against action of tension spring 230a, until joints 226a, 228a strike on the master cylinder 200a, thus blocking any further movement of pedal 62a and thereby preventing overly high pressures from being produced. The blocking of the pedal 62a also signals to a driver that a failure has occurred. Joints 226a, 228a may be equipped with braking means (fig 4) and a three bar chain can be employed (fig 3). Further embodiments include spring and blocking means (figs 5 and 6) which may be actuated hydraulically (fig 7 and 13) or pneumatically (fig 8 and 14). Telescoping and non-telescoping plungers (figs 9 to 12, 15a to 15c and 17) may be used between cylinder 200a and pedal 62a. Also bendable leaf spring (210q, figs 16a-16c) can be provided. Relief and/or blocking valve arrangements (figs 18 to 28) may be included in the hydraulic line between the cylinder 60 and valve 42.