Self-piloting lawn mower

• US 4,184,559 A
• Filed: 10/17/1977
• Issued: 01/22/1980
• Est. Priority Date: 10/17/1977
• Status: Expired due to Term

• Current Assignee: Hans A. Rass
• Original Assignee: Hans A. Rass
• Inventors: Rass, Hans A.
• Primary Examiner(s): Peters, Jr., Joseph F.
• Assistant Examiner(s): McGiehan, Donn
• Application Number:
  US05/842,970
• Time in Patent Office: 827 Days
• Field of Search: 180/131, 180/98, 180/79, 180/79.1, 56/10.2, 56/DIG. 15
• US Class Current: 180/401
• CPC Class Codes: A01D 2101/00 Lawn-mowers
• CPC Class Codes: A01D 34/008 for automated or remotely controlled operation
• CPC Class Codes: B62D 1/26 mechanical, e.g. by a non-load-bearing guide railways B61
• CPC Class Codes: Y10S 56/15 Condition responsive

Abstract

A lawn mower, designed with a set of built-in mechanical sensor and piloting mechanisms, which enable it to pilot itself along the edge line between the grass already cut and grass not yet cut, in a fairly straight course, and then to reverse its direction at the end of a run, move itself sideways towards the uncut grass and proceed with another run. The lawn mower will not move in an area where there is no grass, and an obstacle in its path will reverse it. The lawn mower drive wheels are driven by a planetary gear mechanism which is coupled both to the motor and to rotatable sensor brushes mounted ahead of the drive wheels so that the planetary mechanism transmits power to the drive wheels only when the sensor brushes encounter resistance, such as from uncut grass, ahead of the drive wheels. The planetary gear mechanism is mounted on a guide frame that is pivotally mounted to the drive wheel frame so as to engage a first of two counter-rotating gears linked on the wheel frame to the drive wheels. Forward impact against the guide frame causes it to pivotally rock so as to engage the second of the counter-rotating gears to reverse direction of travel of the lawn mower. The drive wheels of the lawn mower are formed of individual rim segments, each linked by an individual spoke that is pivotally mounted to the hub of the drive wheel, with spring bias latching the drive wheel spokes in a vertical plane except during periods of pivotal rocking motion of the guide frame. When the guide frame rocks to shift direction of travel of the lawn mower, the wheel spokes are unlatched to permit the weight of the assembly to cause the wheel spokes to pivot for a timed period causing the lawn mower to travel sidewise for the duration of the timed period.

Claims

1. A powered lawn mower incorporating mechanical piloting and sensing mechanism so as to direct the lawn mower along a series of straight parallel courses and to cause the lawn mower travel direction to be reversed at the end of each said course, comprising

engine means linked to drive a pair of counter-rotating drive gears,

a planetary differential coupling, the input of which is engageable alternatively with one or the other of said counter-rotating drive gears, with

said planetary differential fitted with two output shafts, one of which is coupled to a rotatable sensor brush, and the other of which is coupled to a drive wheel on which the lawn mower is mounted, such that torque is transmitted to the drive wheel only when the said sensor brush encounters resistance torque, in which

said planetary differential is mounted on a guide frame, which guide frame is pivotally rockably mounted to a wheel frame on which the drive wheel is rotatably mounted, with the input of said planetary differential engageable with the counter-rotating drive gears, such that in a first position of the guide frame, the input of the differential coupling is engaged to a first of said counter-rotating drive gears, and in a second position of the guide frame, the said input is engaged to the second of the two counter-rotating drive gears, so as to result in the rotation of the drive wheel by an output shaft of the differential coupling in a first direction, in the said first position of the guide frame;

and to result in the rotation of the drive wheel by said output shaft in the reverse direction of said first direction, in the second position of the guide frame.

2. A powered lawn mower, incorporating the mechanism recited in claim 1, together with power means to move the lawn mower sidewise to the path of travel of the lawn mower so that upon completion of a straight path of travel in a given direction, with the guide frame in a first position, the lawn mower is moved sidewise by said power means so as to travel along a course parallel to said straight path of travel in the second position of the guide frame along a path in the reverse direction of said given direction.