Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Control of power distribution between vehicle axis or wheels
Reexamination Certificate
2001-05-29
2002-08-20
Nguyen, Tan (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Control of power distribution between vehicle axis or wheels
C701S075000, C701S079000, C180S411000
Reexamination Certificate
active
06438480
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a continuously variable speed-changing device and, more particularly, to a device for changing the speeds of the front and rear wheels in a four-wheel-drive vehicle, capable of variably driving the front wheels and the rear wheels independently from each other by using a toroidal type continuously variable speed-changing device or a belt-type continuously variable speed-changing device.
DESCRIPTION OF THE PRIOR ART
There has heretofore been proposed a four-wheel-drive vehicle equipped with a continuously variable speed-changing mechanism for the front wheels and with a continuously variable speed-changing mechanism for the rear wheels in order to variably drive the front wheel drive shafts and the rear wheel drive shafts independently from each other via the continuously variable speed-changing mechanisms, in an attempt to decrease the weight of the four-wheel-drive mechanisms, to avoid the loss of power and to improve the fuel efficiency.
A typical example of the continuously variable speed-changing device in the four-wheel-drive vehicle can be typified by a toroidal type continuously variable speed-changing device disclosed in Japanese Laid-open Patent Publication (Kokai) No. 157151/1993 (JP-A 5-157151). This continuously variable speed-changing device includes an input shaft supported by a casing, and a continuously variable speed-changing mechanism for the front wheels and a continuously variable speed-changing mechanism for the rear wheels that are arranged, spaced apart, in the axial direction of the input shaft. The continuously variable speed-changing mechanism for the front wheels changes the input rotational speed of the input shaft and outputs it to the front wheel drive shafts. The continuously variable speed-changing mechanism for the rear wheels changes the input rotational speed of the input shaft and outputs it to the rear wheel drive shafts. These continuously variable speed-changing mechanisms have been so constituted as to variably drive the front wheels and the rear wheels independently from each other.
The above continuously variable speed-changing mechanism for the front wheels has substantially the same constitution as that of the continuously variable speed-changing mechanism for the rear wheels. Therefore, the constitution of the continuously variable speed-changing mechanism for the front wheels will now be briefly described. The continuously variable speed-changing mechanism for the front wheels includes an input disk which is secured to the input shaft and has one surface in the axial direction thereof formed as an input side recessed surface of an arcuate shape in cross section, and an output disk having one surface in the axial direction thereof formed as an output side recessed surface of an arcuate shape in cross section. The output disk is so disposed as to rotate relative to the input shaft and to surround the outer peripheral surface of the input shaft and has its output side recessed surface disposed so as to be opposed to the input side recessed surface of the input disk in the axial direction. A pair of power rollers are disposed between the input side recessed surface of the input disk and the output side recessed surface of the output disk so as to rotate relative to the input disk and the output disk. The power rollers are supported by trunnions so as to rotate. The axes of rotation of the power rollers are arranged at right angles with the axes of the trunnions that will be described later.
The trunnions are so supported as to rotate about their axes relative to the casing and to move in the axial direction. The axes of the trunnions extend in parallel with each other in the tangential direction relative to the input shaft at symmetrical positions with the input shaft interposed therebetween at an equal distance. On the cross sections of the input disk and of the output disk opposed to each other in the axial direction, the center of arc of the input side recessed surface of the input disk and the center of arc of the output side recessed surface of the output disk are arranged on a common center of arc. Further, the axial centers of the trunnions are arranged to be in agreement with the centers of the corresponding arcs. The axes of the trunnions define tilting axes along which the corresponding power rollers rotate. The power rollers are so constituted as to possess spherically protruded surfaces in the peripheries thereof, the protruded surfaces being brought into a pressed contact (point contact) with the input side recessed surface of the input disk and with the output side recessed surface of the output disk. The trunnions are moved in the axial directions but in the opposite directions relative to each other by the actuators such as hydraulic cylinders, whereby the power rollers rotate about the axes which are tilted by an angle corresponding to the amount of motion of the trunnions and changing of the speed between the input disk and the output disk is performed. According to the toroidal type continuously variable speed-changing device as described above, the rotational forces of the output disks of the continuously variable speed-changing mechanism for the front wheels and of the continuously variable speed-changing mechanism for the rear wheels are output to the front wheels and to the rear wheels independently from each other, to execute the full-time four-wheel drive. Constitutions of trunnions of the toroidal type continuously variable speed-changing device have been disclosed in, for example, Japanese Utility Model Publication (Kokoku) No. 11425/1994 and Japanese Laid-open Patent Publication (Kokai) No. 269039/1997 (JP-A 9-269039).
In the continuously variable speed-changing device, when a steering angle is given to the front wheels, the tilting angle of the power rollers of the continuously variable speed-changing mechanism for the front wheels is differed from the tilting angle of the power rollers of the continuously variable speed-changing mechanism for the rear wheels to drive the four wheels with little loss of power while absorbing the difference in rotational speed between the front wheels and the rear wheels when the vehicle turns, without using the center differential.
Another typical example of the continuously variable speed-changing device can be represented by a belt-type continuously variable speed-changing device. This continuously variable speed-changing device employs a belt-type continuously variable speed-changing mechanism for the front wheels and a belt-type continuously variable speed-changing mechanism for the rear wheels instead of the above-mentioned toroidal type continuously variable speed-changing mechanism for the front wheels and the toroidal type continuously variable speed-changing mechanism for the rear wheels. Each of the belt-type continuously variable speed-changing mechanism for the front wheels and the belt-type continuously variable speed-changing mechanism for the rear wheels comprises a primary pulley having a pulley fixed to the primary shaft drive-coupled to the output shaft of the engine and a movable pulley which is opposed to the fixed pulley and can move in the axial direction, a secondary pulley having a pulley fixed to the secondary shaft and a movable pulley which is opposed to the fixed pulley and can move in the axial direction, and a drive belt wrapped round the primary pulley and the secondary pulley. Upon changing the gaps of the pulley grooves of the primary pulley and of the secondary pulley, the belt-wrapping diameters of the pulleys change and the speed-changing ratio between the primary shaft and the secondary shaft is continuously adjusted. Even by using the thus constituted belt-type continuously variable speed-changing device, the front wheels and the rear wheels can be variably driven independently from each other by the continuously variable speed-changing mechanism for the front wheels and by the continuously variable speed-changing mechanism for the rear wheels in substantially the same manner as i
Koga Hidetaka
Tanaka Hirohisa
Antonelli Terry Stout & Kraus LLP
Isuzu Motors Limited
Nguyen Tan
LandOfFree
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