Belt-type continuously variable transmission

#This is the U.S. national stage of application No. PCT/JP2012/055130, filed on 29 Feb. 2012. Priority under 35 U.S.C. §119(a) and 35 U.S.C. §365(b) is claimed from Japanese Application Nos. 2011-133554 and 2011-139948, filed 15 Jun. 2011 and 23 Jun. 2011, respectively, the disclosures of both of which are also incorporated herein by reference.

#The present invention relates to a technique of a belt-type continuously variable transmission, and more particularly relates to a technique of a belt-type continuously variable transmission in which a movable sheave is provided with a hydraulic cylinder, and the feeding of hydraulic oil to the hydraulic cylinder is controlled by a hydraulic servo mechanism.

#A technique described in Patent Literature 1 has been known as a conventional technique of a belt-type continuously variable transmission in which a driving force is transmitted with a belt being wound across a pair of pulleys having a variable groove width.

#FIG. 1 It is a sideward cross-sectional view showing the overall structure of a transmission comprising a belt-type continuously variable transmission according to one embodiment of the present invention.

#FIG. 2 It is a sideward cross-sectional view showing an input pulley, a hydraulic cylinder, a hydraulic servo mechanism, etc. of the belt-type continuously variable transmission.

#FIG. 3 It is a perspective view showing a movable side cylinder casing.

#Hereinafter, an explanation will be given of a transmission 7 which is a transmission device of a working vehicle with reference to FIG. 1. The transmission 7 according to the present embodiment is provided in a tractor which is an agricultural vehicle. However, the present invention is not limited thereto and can be employed generally for vehicles such as another agricultural vehicle, construction vehicle, industrial vehicle etc. In below explanation, a direction of an arrow F in the drawing is defined as the front direction.

#The transmission 7 changes power from an engine (not shown in Figures), being a drive source, in speed and then outputs it. The transmission 7 includes a mission input shaft 20, a clutch mechanism 200, a belt-type continuously variable transmission 40, an output shaft 170, a front wheel driving transmission shaft 180, a PTO brake 210, a PTO input shaft 220, a rear PTO shaft 230, a mid PTO shaft 240, etc.

#The power from the engine is transmitted to the mission input shaft 20, and then transmitted to the belt-type continuously variable transmission 40 and the PTO input shaft 220 via the clutch mechanism 200. The power transmitted to the belt-type continuously variable transmission 40 is changed steplessly in speed at the belt-type continuously variable transmission 40, and then transmitted to the output shaft 170 and the front wheel driving transmission shaft 180. The power transmitted to the output shaft 170 is then transmitted to rear wheels (not shown in Figures) of the tractor via a final reduction mechanism (not shown in Figures) etc. The power transmitted to the front wheel driving transmission shaft 180 is then transmitted to front wheels (not shown in Figures) of the tractor via a front axle shaft (not shown in Figures). And the power transmitted to the PTO input shaft 220 is then transmitted to the rear PTO shaft 230 and the mid PTO shaft 240 via gears etc.