Automatic self-guiding lawn mower and mowing method

• US 5,007,234 A
• Filed: 08/15/1990
• Issued: 04/16/1991
• Est. Priority Date: 11/27/1989
• Status: Expired due to Fees

• Current Assignee: Darlene M. Shurman, Gerald L. Shurman, Louis W. Shurman
• Original Assignee: Darlene M. Shurman, Gerald L. Shurman, Louis W. Shurman
• Inventors: Shurman, Louis W., Shurman, Darlene M., Shurman, Gerald L.
• Primary Examiner(s): Britts, Ramon S.
• Assistant Examiner(s): MELIUS, TERRY L
• Application Number:
  US07/568,221
• Time in Patent Office: 244 Days
• Field of Search: 56/10.2-16.7, 56/DIG. 2, 56/DIG. 3, 56/DIG. 15, 180/131, 180/167, 180/79.1, 180/6.5
• US Class Current: 56/10.20R
• CPC Class Codes: A01D 2101/00 Lawn-mowers
• CPC Class Codes: A01D 34/008 for automated or remotely controlled operation
• CPC Class Codes: G05D 1/0227 using mechanical sensing means, e.g. for sensing treated area
• CPC Class Codes: G05D 1/0272 comprising means for registering the travel distance, e.g. revolutions of wheels measuring distance traversed on the ground by vehicles, e.g. using odometers G01C22/00
• CPC Class Codes: Y10S 56/02 Methods
• CPC Class Codes: Y10S 56/15 Condition responsive

Abstract

An automatic self-guiding lawn mower includes a carriage having first and second sets of electric motors mounted thereon. A blade is operatively connected to and driven by each one of the first set of electric motors for cutting grass, and a wheel is operatively connected to and driven by each one of the second set of motors for moving the carriage. A relay device having at least one trip point is electrically connected to each of the first motors and to the second set of motors. The method of mowing a lawn with the improved lawn mower includes the steps of actuating the first set of motors and attached blades and manually cutting a border around the lawn with the mower. The mower then is positioned adjacent to a peripheral edge of an uncut area of the lawn. The relay devices detect a predetermined change in the power consumption of their respective first motors corresponding to the trip point when the attached blades move between cut and uncut grass, and actuate certain ones of the second motors and attached wheels in response thereto for guiding the mower carriage along the peripheral edge of the uncut area of the lawn. The relay devices reverse the polarity of the second motors and the direction of the mower when the blades encounter cut grass for a first predetermined amount of time, and automatically shut off the first and second motors when the blades encounter cut grass for a second predetermined amount of time.

Claims

1. An automatic self-guiding lawn mower, including:

(a) a carriage;

(b) at least one first motor and at least one second motor mounted on the carriage;

(c) blade means operatively connected to and driven by the first motor for cutting a lawn;

(d) wheel means operatively connected to and driven by the second motor for moving the carriage in a predetermined path; and

(e) sensor means connected to the first and second motors for detecting a predetermined change in the operation of the first motor when the blade means moves between a cut area and an uncut area of the lawn, and for causing a certain change in the second motor upon detection of the predetermined change in the first motor, so that the carriage is moved in said predetermined path through the uncut area of the lawn.

2. The lawn mower defined in claim 1 in which the first and second motors are electric motors.

3. The lawn mower defined in claim 2 in which the electric motors are low power motors;

and in which a battery is mounted on the carriage for supplying power to the motors.

4. The lawn mower defined in claim 1 in which the first and second motors are hydraulic motors.

5. The lawn mower defined in claim 1 in which the first and second motors are pneumatic motors.

6. The lawn mower defined in claim 1 in which the first and second motors are internal combustion motors.

7. The lawn mower defined in claim 1 in which the sensor means is a relay device;

in which the relay device includes at least one trip point; and

in which the relay device is electrically connected to the first and second motors, for detecting a predetermined change in the power consumption of the first motor corresponding to the trip point when the blade means moves between a cut area and an uncut area of the lawn, and for actuating the second motor and attached wheel means in response thereto.

8. The lawn mower defined in claim 7 in which the relay device includes timer means for reversing the polarity of the second motor and direction of the lawn mower when the blade means encounters a cut area of the lawn for a first predetermined amount of time.

9. The lawn mower defined in claim 7 in which the relay device includes timer means for automatically shutting off the first and second motors when the blade means encounters a cut area of the lawn for a second predetermined amount of time.

10. The lawn mower defined in claim 1 in which at least a pair of the second motors are mounted in a spaced relationship on the carriage;

and in which the direction of spacing of the second motors is generally perpendicular to the direction of movement of the carriage.

11. The lawn mower defined in claim 1 in which at least a pair of the first motors are mounted in a spaced relationship on the carriage;

and in which the direction of spacing of the first motors is the same as the direction of movement of the carriage.

12. The lawn mower defined in claim 11 in which the blade means is an elongated plastic blade horizontally mounted on an output shaft of each of the first motors beneath the carriage;

and in which a circumference of rotation of the blade of each of the first motors is spaced from the circumference of rotation of the blade of the other first motor in the direction of movement of the carriage.

13. A method of mowing a lawn with an automatic self-guiding lawn mower having at least first and second motor means for driving operatively connected blade means and wheel means, respectively, for cutting the lawn and moving the mower, including the steps of:

(a) manually cutting a border around the lawn;

(b) positioning the mower adjacent to a peripheral edge of an uncut area of the lawn;

(c) actuating the first motor means for driving the operatively connected blade means;

(d) actuating the second motor means for driving the operatively connected wheel means to move the mower in a curved path into the uncut area of the lawn;

(e) sensing a predetermined change in the operation of the first motor means when the attached blade means moves to a certain position in an uncut area of the lawn; and

(f) causing a certain change in the second motor means upon detection of the predetermined change in the first motor means when the mower means reaches said certain position in the uncut area so that the mower moves in a generally straight line along the peripheral edge of the uncut area of the lawn.

14. The method defined in claim 13 including the step of sensing a predetermined change in the power consumption of the first motor means when the blade means moves between a cut area and an uncut area of the lawn, and actuating the second motor means and attached wheel means in response thereto.

15. The method defined in claim 13 including the step of reversing the polarity of the second motor means and direction of the lawn mower when the blade means encounters a cut area of the lawn for a first predetermined amount of time.

16. The method defined in claim 13 including the step of automatically shutting off the first and second motor means when the blade means encounters a cut area of the lawn for a second predetermined amount of time.