Roller brush for surface cleaning robots

• US 10,292,560 B2
• Filed: 04/01/2016
• Issued: 05/21/2019
• Est. Priority Date: 03/15/2013
• Status: Active Grant

• Current Assignee: iRobot Corporation
• Original Assignee: iRobot Corporation
• Inventors: Doughty, Brian
• Primary Examiner(s): Chin, Randall E
• Application Number:
  US15/088,802
• Publication Number:
  US 20160213217A1
• Time in Patent Office: 1,145 Days
• CPC Class Codes: A47L 11/24 Floor-sweeping machines, motor-driven
• CPC Class Codes: A47L 11/282 having rotary tools
• CPC Class Codes: A47L 11/32 Carpet-sweepers combined with suction cleaners A47L7/02
• CPC Class Codes: A47L 11/33 having means for storing dirt
• CPC Class Codes: A47L 11/4041 Roll shaped surface treating tools
• CPC Class Codes: A47L 11/4072 Arrangement of castors or wheels
• CPC Class Codes: A47L 2201/00 Robotic cleaning machines, i.e. with automatic control of the travelling movement or the cleaning operation
• CPC Class Codes: A47L 2201/06 Control of the cleaning action for autonomous devices; Automatic detection of the surface condition before, during or after cleaning
• CPC Class Codes: A47L 9/009 Carrying-vehicles; Arrangements of trollies or wheels; Means for avoiding mechanical obstacles
• CPC Class Codes: A47L 9/04 with driven brushes or agitators
• CPC Class Codes: A47L 9/0477 Rolls

Abstract

A mobile surface cleaning robot that includes a robot body having a forward drive direction and a drive system supporting the robot body above a floor surface. The drive system includes right and left drive wheels and a caster wheel assembly disposed rearward of the drive wheels. The caster wheel assembly includes a caster wheel supported for vertical movement and a suspension spring biasing the caster wheel toward the floor surface. The robot also includes a cleaning system supported by the robot body forward of the drive wheels and having at least one cleaning element that engages the floor surface. The suspension spring has a spring constant sufficient to elevate a rear end of the robot body above the floor surface to maintain engagement of the at least one cleaning element with the floor surface.

Claims

1. A mobile surface cleaning robot comprising:

a robot body having a forward drive direction;

a drive system supporting the robot body above a floor surface for maneuvering the robot across the floor surface, the drive system comprising;

right and left drive wheels disposed on corresponding right and left portions of the robot body; and

a caster wheel assembly disposed rearward of the drive wheels, the caster wheel assembly including a caster wheel supported for vertical movement and a suspension spring biasing the caster wheel toward the floor surface; and

a cleaning system supported by the robot body forward of the drive wheels, the cleaning system comprising at least one cleaning element configured to engage the floor surface,

wherein the suspension spring has a spring constant sufficient to elevate a rear end of the robot body above the floor surface to maintain engagement of the at least one cleaning element with the floor surface.

2. The robot of claim 1, wherein a center of gravity of the robot is located forward of the drive wheels, allowing the robot body to pivot forward about the drive wheels.

3. The robot of claim 2, wherein the center of gravity of the robot is located forward of the drive wheels by a distance of between 0% and 35% of a distance between a drive axis of the drive wheels and a forward end of the robot body, causing engagement of the at least one cleaning element with the floor surface.

4. The robot of claim 1, further comprising at least one clearance regulator supported by the robot body and disposed forward of the drive wheels and rearward of the at least one cleaning element, the at least one clearance regulator providing a minimum clearance height between a bottom surface of the robot body and the floor surface.

5. The robot of claim 4, wherein the minimum clearance height is at least 2 mm.

6. The robot of claim 4, wherein the at least one clearance regulator comprises a roller rotatably supported by the robot body.

7. The robot of claim 1, wherein the drive system further comprises:

right and left drive wheel suspension arms supporting the respective right and left drive wheels, each drive wheel suspension arm having a first end pivotally coupled to the robot body and a second end rotatably supporting the drive wheel; and

right and left drive wheel suspension springs biasing the respective right and left drive wheels toward the floor surface.

8. The robot of claim 7, wherein each drive wheel suspension arm defines a pivot point, a wheel pivot, and a spring anchor spaced from the pivot point and the wheel pivot, each drive wheel suspension arm comprising a drive wheel suspension spring biasing the spring anchor, causing the drive wheel suspension arm to rotate about the pivot point to move the corresponding drive wheel toward the floor surface.

9. The robot of claim 8, wherein the drive wheel suspension spring provides a spring force equal to between 40% and 80% of an overall weight of the robot.

10. The robot of claim 8, wherein each drive wheel suspension arm defines an L-shape having first and second legs, the pivot point of the drive wheel suspension arm positioned at least below half a height of the robot body with respect to the floor surface.

11. The robot of claim 10, wherein a hypotenuse of the L-shaped drive wheel suspension arm has a length equal to between 70% and 150% of the height of the robot body.

12. The robot of claim 11, wherein a maximum allowable weight limit per drive wheel for clockwise and counter clockwise rotation is determined as:

13. The robot of claim 12, wherein each drive wheel has a diameter equal to between 75% and 120% of a height of the robot body.

14. The robot of claim 1, wherein the at least one cleaning element comprises a roller brush having bristles, the suspension spring elevating the rear end of the robot body above the floor surface to cause engagement of at least 5% of a bristle length of the roller brush bristles with the floor surface.

15. The robot of claim 14, wherein the roller brush comprises:

a brush core defining a longitudinal axis of rotation; and

three or more dual rows of bristles disposed on and equidistantly spaced along a circumference the brush core, each dual row of bristles comprising;

a first bristle row comprising a first bristle composition and having a first height; and

a second bristle row comprising a second bristle composition and having a second height, the second bristle row circumferentially spaced from the first bristle row by a gap less than or equal to 10% of the second height, the first height being less than or equal to 90% of the second height, wherein the first bristle composition is stiffer than the second bristle composition.

16. The robot of claim 15, wherein at least 5% of the second height of the second bristle row engages with the floor surface.

17. The robot of claim 15, wherein the first bristle row of each dual bristle row is forward of the second bristle row in a direction of rotation of the roller brush.

18. The robot of claim 15, wherein the roller brush further comprises elastomeric vanes arranged between and substantially parallel to the bristle rows, each vane extending from a first end attached to the brush core to a second end unattached from the brush core.

19. The robot of claim 1, wherein the at least one cleaning element comprises:

a first roller brush comprising;

a brush core defining a longitudinal axis of rotation; and

three or more dual rows of bristles disposed on and equidistantly spaced along a circumference the brush core, each dual row of bristles comprising;

a first bristle row comprising a first bristle composition and having a first height; and

a second bristle row comprising a second bristle composition and having a second height, the second bristle row circumferentially spaced from the first bristle row by a gap less than or equal to 10% of the second height, the first height being less than or equal to 90% of the second height, wherein the first bristle composition is stiffer than the second bristle composition; and

a second roller brush arranged rotatably opposite the first roller brush, the second roller brush comprising;

a brush core defining a longitudinal axis of rotation; and

three or more rows of bristles disposed on and circumferentially spaced about the brush core.

20. The robot of claim 1, wherein the robot body defines a square front profile or a round profile.