Vehicle wiper device

1. A vehicle wiper device that moves a wiper back and forth between a bottom reversing position and a top reversing position, the vehicle wiper device comprises:

at least one drive source including an output shaft, wherein the drive source rotates the output shaft back and forth about a first axis within a rotational angle range of less than 360°; and

at least one link mechanism coupled to the output shaft, wherein the link mechanism includes a wiper joint coupled to the wiper, the link mechanism is configured to rotate the wiper joint back and forth around a second axis within a rotational angle range that is smaller than the rotational angle range of the output shaft, and the link mechanism is configured so that torque of the wiper joint is greater when the wiper is at the bottom reversing position than when the wiper is at the top reversing position wherein

the link mechanism includes:

a crank including a basal end, which is fixed to the output shaft, and an opposite distal end;

a rod including a basal end, which is coupled to the distal end of the crank rotatably about a third axis, and an opposite distal end; and

a lever including a basal end, coupled to the distal end of the rod rotatably about a fourth axis, and an opposite distal end, with which the wiper joint is fixed, wherein the second axis of the wiper joint is separated from the first axis of the output shaft,

the link mechanism is configured so that the first axis, the third axis, and the fourth axis are arranged along a straight line as viewed in axial directions of the first, third, and fourth axes when the wiper is at the bottom reversing position, and

the rod pivots about the fourth axis in a pivotal direction and the pivotal direction is reversed when the crank reaches an intermediate reversing position located between a position of the crank when the wiper is located at the bottom reversing position and a position of the crank when the wiper is located at the top reversing position.

2. The vehicle wiper device according to claim 1 , wherein the second axis, the first axis, and the third axis are arranged along a straight line when the crank is at the intermediate reversing position.

3. The vehicle wiper device according to claim 2 , wherein when a rotational angle range of the crank and the output shaft is divided into three angle ranges, the intermediate reversing position is located in a middle one of the three angle ranges.

4. The vehicle wiper device according to claim 1 , further comprising:

a bracket fixed to the drive source and a vehicle, wherein the bracket includes a support sleeve that supports the wiper joint so that the wiper joint is rotatable about the second axis, and

wherein the link mechanism is configured by sequentially stacking the crank, the rod, and the lever in this order on the drive source and coupling together the crank, the rod, and the lever.

5. The vehicle wiper device according to claim 1 , wherein

the drive source includes a motor body and a worm gear, and

the link mechanism is configured so that the second axis of the wiper joint is overlapped with the worm gear as viewed from an axial direction of the output shaft.

6. The vehicle wiper device according to claim 1 , wherein the link mechanism is configured so that a torque of the wiper joint when the wiper is at the bottom reversing position is two times or greater than a torque of the wiper joint when the wiper is at the top reversing position.

7. The vehicle wiper device according to claim 1 , wherein

the drive source and the link mechanism forms a driver coupled to the wiper,

the driver is one of a plurality of drivers respectively arranged proximal to two ends of a windshield in a lateral direction of a vehicle, and

wipers respectively coupled to the drivers are overlapped with each other in a wiping direction at the bottom reversing position.

8. The vehicle wiper device according to claim 1 , wherein

the wiper is moved back and forth on a windshield,

the drive source is fixed to a vehicle,

the drive source and the link mechanism form a driver that is arranged in the vehicle below at least one of two ends of the windshield in a lateral direction of the vehicle, and

the driver is configured so that the second axis of the wiper joint is located outwardly in the lateral direction of the vehicle from the first axis of the output shaft.

9. The vehicle wiper device according to claim 8 , wherein

the drive source includes a motor body and a worm gear,

the motor body includes a rotation shaft rotated and driven by the motor body,

the worm gear rotates the output shaft to reduce the rotation speed of the rotation shaft, and

the driver is configured so that the motor body is arranged at a position located inwardly in the lateral direction of the vehicle from the first axis.

10. The vehicle wiper according to claim 8 ,

wherein the link mechanism is configured so that the third axis, and the fourth axis are arranged inwardly in the lateral direction of the vehicle from the second axis regardless of the rotational angle of the wiper joint.