Non-stage transmission for vehicles and lawn mowing tractor using same

A continuously variable speed transmission for vehicle comprising:

• an input shaft drivingly connected to a vehicle-mounted engine;
• a first rotation shaft placed in parallel with the input shaft;
• a power transmission mechanism, provided between the input shaft and the first rotation shaft, for transmitting power between the input shaft and the first rotation shaft at a constant ratio;
• a second rotation shaft placed coaxially with the first rotation shaft;
• a belt variable speed mechanism, including two variable speed pulleys with a variable pulley diameter respectively provided on the input shaft and the second rotation shaft for unitary rotation and a variable speed belt wound between both the variable speed pulleys, for transmitting power between the input shaft and the second rotation shaft at a variable ratio;
• a differential gear mechanism which includes a first gear element connected to the first rotation shaft, a second gear element connected to the second rotation shaft and a third gear element changing its rotational direction and rotational speed with the change in the circumferential speed difference between the first and second gear elements and is enclosed in a casing;
• and
• an output shaft coaxially placed with the first and second rotation shafts and drivingly connected to the third gear element,
• wherein the power transmission mechanism is formed of a belt power transmission mechanism including two pulleys respectively provided on the input shaft and the first rotation shaft for unitary rotation and a power transmission belt wound around both the pulleys,
• both the pulleys and the power transmission belt of the belt power transmission mechanism are placed in a plane parallel with a plane in which both the variable speed pulleys and the variable speed belt of the belt variable speed mechanism are provided, and
• the casing is placed between the belt power transmission mechanism and the belt variable speed mechanism.