Two-wheel drive and four-wheel drive change-over apparatus and driving actuator

An actuator is provided with an output shaft connected to a driving gear, a pair of cam followers turned by the shaft and driving the cams held on driven shafts urging members held in housings of the driving gear, a rotation retaining plate mounted on the output shaft so that the rotation retaining plate cannot be rotated relatively to the output shaft, a plurality of pressing parts formed on the rotation retaining plate so as to project there from, and slits for preventing the driving gear and pressing parts from interfering with each other. The rotation of the driving gear is transmitted to the output shaft via the springs and rotation retaining plate. When the rotation of the driving gear is continued with the output shaft locked and stopped, one of both end portions of each spring is pressed by the corresponding pressing member.

1. An actuator for actuating at least two driven shafts arranged in parallel with each other in axial directions thereof, through cams held on the driven shafts for driving the driven shafts respectively, so that each driven shaft is selectively moved in the axial direction thereof by a predetermined stroke by driving each cam to a predetermined stopping position in accordance with a mode changed over from another mode among a plurality of modes to be switched, the actuator comprising:

a motor;; a driving gear meshed with a worm formed on a shaft of the motor;; an output shaft connected to the driving gear;; a pair of cam followers turning by a rotation of the output shaft, and engaged with the cams so as to drive the cams;; a plurality of urging members respectively held in a plurality of urging member housings formed at predetermined intervals along a circle on a side face of the driving gear;
a rotation retaining plate fixed on the output shaft so as not to rotate relative to the output shaft;

a plurality of pressing parts each of which projects from the rotation retaining plate, and each of which is capable of pressing one of both end portions of the corresponding urging member;

slits formed on the driving gear between adjacent ones of the urging member housings so as to prevent the pressing parts from interfering with the driving gear;

a first actuator case in which the driving gear, the rotation retaining plate and the output shaft are housed; and

a second actuator case fixed to the first actuator case, supporting each driven shaft so that the driven shafts are moved freely in the axial direction thereof and housing each of the cams therein,

wherein a rotation of the driving gear is transmitted to the output shaft via the urging members and the rotation retaining plate, either one of both end portions of each of the urging members being pressed by the corresponding pressing part of the rotation retaining plate when the rotation of the driving gear is continued after the output shaft is locked and stopped in an intermediate position of the rotation thereof.

2. An actuator according to claim 1, wherein the urging member housings formed on the driving gear are three arcuate urging member housings arranged at regular intervals in the circumferential direction thereof, the urging members being three cylindrical compression springs.

3. An actuator for actuating a two-wheel drive and four-wheel drive change-over apparatus having a first change-over shaft for switching two-wheel drive/four-wheel drive and a second change-over shaft for changing speeds of four wheels, the first and second change-over shaft being arranged in parallel with each other in a transfer and movable in axial directions thereof by cams held on the first and second change-over shafts for driving the first and second change-over shafts respectively, wherein the actuator is adapted to switch selectively from one to another of four driving conditions including two-wheel drive, four-wheel high-speed drive, four-wheel neutral and four-wheel low-speed driving condition by driving the cams in the change-over apparatus to predetermined stopping positions respectively in accordance with a mode changed by a shifting operation of a mode change-over switch, and thereby moving the change-over shafts selectively in the axial directions at predetermined strokes, the actuator including:

a motor;

a driving gear meshed with a worm formed on a shaft of the motor;

an output shaft connected to the driving gear;

a pair of cam followers turning by a rotation of the output shaft, and engaged with the cams so as to drive the cams;

a plurality of urging members respectively held in a plurality of urging member housings formed at predetermined intervals along a circle on a side face of the driving gear;

a rotation retaining plate fixed on the output shaft so as not to rotate relative to the output shaft;

a plurality of pressing parts each of which projects from the rotation retaining plate, and each of which is capable of pressing either one of both end portions of a corresponding urging member;

slits formed on the driving gear between adjacent ones of the urging member housings so as to prevent the pressing parts from interfering with the driving gear;

a first actuator case in which the driving gear, the rotation retaining plate and the output shaft are housed; and

a second actuator case fixed to the first actuator case, supporting each driven shaft so that the driven shafts are moved freely in the axial direction thereof and housing each of the cams therein,

4. An actuator for driving a two-wheel drive and four-wheel drive change-over apparatus according to claim 3,

wherein the urging member housings formed on the driving gear are three arcuate urging member housings formed on the driving gear at regular intervals in the circumferential direction thereof, the urging members being three cylindrical compression springs.

5. A two-wheel drive and four-wheel drive change-over apparatus having a first change-over shaft for switching two-wheel drive/four-wheel drive and a second change-over shaft for changing speeds of four wheels, the first and second change-over shafts being arranged in parallel with each other in a transfer and movable in axial directions thereof, cams held on the first and second change-over shafts for driving the first and the second change-over shafts respectively, and an actuator adapted to be driven rotationally to predetermined stopping positions respectively in accordance with a mode changed by a switching operation of a mode change-over switch, and drive each cam and thereby move the change-over shafts selectively in the axial directions thereof at predetermined strokes, the actuator including:

a motor;

a driving gear meshed with a worm formed on a shaft of the motor;

an output shaft connected to the driving gear;

a pair of cam followers turning by a rotation of the output shaft, and engaged with the cams so as to drive the cams;

a plurality of urging members respectively held in a plurality of urging member housings formed at predetermined intervals along a circle on a side face of the driving gear;

a rotation retaining plate fixed on the output shaft so as not to rotate relative to the output shaft;

a plurality of pressing parts each of which projects from the rotation retaining plate, and each of which is capable of pressing either one of both end portions of a corresponding urging member;

slits formed on the driving gear between adjacent ones of the urging member housings so as to prevent the pressing parts from interfering with the driving gear;

a first actuator case in which the driving gear, the rotation retaining plate and the output shaft are housed; and

a second actuator case fixed to the first actuator case, supporting each driven shaft so that the driven shafts are moved freely in the axial direction thereof and housing each of the cams therein,

6. A two-wheel drive and four-wheel drive change-over apparatus according to claim 5, wherein the plural urging member housings formed on the driving gear are three arcuate urging member housings formed at predetermined intervals along a circle which is the same as an outer circumference of the driving gear, the urging members being three cylindrical compression springs.

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