Battery-powered lawn cutting system

• US 5,606,851 A
• Filed: 10/13/1995
• Issued: 03/04/1997
• Est. Priority Date: 09/22/1993
• Status: Expired due to Term

• Current Assignee: Briggs & Stratton Corporation
• Original Assignee: Briggs & Stratton Corporation
• Inventors: Pfaff, Joseph L., Bruener, Patrick J., Fiorenza, John A. II, Dykstra, Richard A., Tharman, Paul A., Reitman, William H.
• Primary Examiner(s): Melius, Terry Lee
• Application Number:
  US08/543,054
• Time in Patent Office: 508 Days
• Field of Search: 56/11.9, 56/10.8, 56/17.1, 56/17.2, 56/16.7, 56/17.5, 56/255, 56/295, 56/DIG. 17, 56/DIG. 20, 56/DIG. 18, 16/110, 16/111
• US Class Current: 56/11.9
• CPC Class Codes: A01D 2034/6843 Control levers on the handle of the mower
• CPC Class Codes: A01D 2101/00 Lawn-mowers
• CPC Class Codes: A01D 34/6806 Driving mechanisms for the cutters A01D34/76
• CPC Class Codes: A01D 34/74 Cutting-height adjustment
• CPC Class Codes: A01D 34/78 electric
• CPC Class Codes: A01D 34/81 Casings; Housings A01D34/71 takes precedence
• CPC Class Codes: A01D 34/82 Other details
• CPC Class Codes: A01D 34/828 Safety devices
• CPC Class Codes: Y10S 56/18 Handles

Abstract

The improved battery-powered lawnmower includes a safety key that is automatically removed when the removable battery is removed, while at the same time blocking the battery recharger receptacle. The lawnmower also includes a control circuit that shuts off the lawnmower upon the occurrence of one or more of several predetermined conditions, including low battery voltage, the encountering of heavy grass for a period of 3 seconds or more, and high motor current that may occur when the cutting blade is jammed. The cutting blade is designed to move through any debris accumulated between the blade ends and the housing sidewall without sacrificing the lift for needed cutting and mulching. The invention also includes a unique height adjustment assembly for adjusting the height of the chassis, a handle attachment that allows the handle to be positively tightened to the lawnmower chassis, and a telescoping groove for the battery'"'"'s quick connect/disconnect terminals.

Claims

1. A height adjustment apparatus that adjusts the height of a lawnmower chassis, comprising:

a first wheel axle having first and second ends;

a first pivot arm, interconnected with said first end of said first axle, and having a first pivot interconnected with said chassis;

a second pivot arm, interconnected with said second end of said first axle, having a second pivot interconnected with said chassis, said first axle and said chassis being the only members that directly connect said first and second pivot arms to each other;

a second wheel axle having first and second ends;

a third pivot arm, interconnected with said first end of said second axle, having a third pivot interconnected with said chassis;

a fourth pivot arm, interconnected with said second end of said second axle, having a fourth pivot interconnected with said chassis, said second axle and said chassis being the only members that directly connect said third and fourth pivot arms to each other;

means for pivoting said first pivot arm about its first pivot; and

link means for pivoting said third pivot arm about its third pivot in response to the pivoting of said first pivot arm;

whereby the pivoting of said first pivot arm by said pivoting means rotates said first wheel axle to thereby pivot said second pivot arm about said second pivot;

whereby the pivoting of said first pivot arm by said pivoting means causes said link means to pivot said third pivot arm about its third pivot; and

whereby the pivoting of said third pivot arm by said link means rotates said second wheel axle to pivot said fourth pivot arm about said fourth pivot, thereby adjusting the height of said lawnmower chassis.

2. The height adjustment apparatus of claim 1, further comprising:

a spring affixed between said link means and either said first or second pivot arms.

3. The height adjustment apparatus of claim 1, wherein said pivoting means includes:

an adjustment lever interconnected with said first pivot arm; and

means for retaining said adjustment lever in one of a plurality of fixed positions.

4. The height adjustment apparatus of claim 3, wherein said retaining means comprises:

a plurality of slots, said adjustment lever being positioned in one of said slots.

5. A control system for a battery-powered lawnmower comprising:

a lawnmower handle having a first end interconnected with a chassis of said lawnmower, and having an opposed second handle end disposed away from said chassis;

a deadman control interconnected with said second end of said handle, said deadman control including a movable member that is held by an operator during operation of said lawnmower, and that is released by said operator to stop said lawnmower;

means for stopping said lawnmower upon the occurrence of at least one predetermined condition; and

means for restarting said lawnmower after said lawnmower has been stopped by said stopping means, by releasing said movable member and by thereafter moving said movable member.

6. The control system of claim 5, wherein said movable member is an elongated handle.

7. The control system of claim 5, wherein said movable member is a push button of a push button switch.

8. The control system of claim 5, wherein said at least one predetermined condition includes a low battery voltage.

9. The control system of claim 5, wherein said predetermined condition includes an overcurrent condition that lasts more than a preset time period.

10. A safety device for a battery-powered lawnmower, said lawnmower having a chassis, said safety device comprising:

a removable battery, including

a surface disposed near an upper end of said battery;

at least one electrical connector interconnected with said chassis;

a removable key, including

at least one electrically conductive member that engages said electrical connector to allow said lawnmower to operate; and

an engagement member that causes said battery and said key to engage each other, whereby the removal of said battery also disengages said electrically conductive member from said electrical connector.

11. The safety device of claim 10, further comprising a handle affixed to said key.

12. The safety device of claim 10, wherein

said battery includes a recharger connector that receives a connector from a battery recharger;

and wherein

said removable key includes a means for blocking said recharger connector when said electrically conductive member is connected to said battery electrical connector.

13. The safety device of claim 12, wherein said blocking means includes a substantially flat surface on said key.

14. The safety device of claim 10, wherein said engagement member is a flange.

15. The safety device of claim 10, wherein said engagement member prevents said battery from being replaced after said battery has been removed and if said key has been replaced.

16. A safety device for a battery-powered lawnmower, said lawnmower having a chassis, said safety device comprising:

a removable battery;

at least one electrical connector interconnected with said chassis;

a removable key, including

at least one electrically conductive member that engages said electrical connector to allow said lawnmower to operate; and

an alarm circuit that provides an alarm when the electrically conductive member of said key engages said electrical connector.

17. A handle attachment assembly for a lawnmower, comprising:

two channels disposed on opposite sides of a mower housing of said lawnmower, each of said channels including;

a first sidewall;

a second sidewall that is non-parallel to said first sidewall;

a lawnmower handle member having two ends, each end being received in one of said channels, wherein the shape of an outer surface of the handle member end corresponds to the shape of the channel into which the handle member is received; and

means for attaching each of said handle members to said housing.

18. The handle attachment assembly of claim 17, wherein said attachment means includes:

a first aperture in each of said channels;

a second aperture in each of said handle member ends; and

a threaded bolt that is received in both of said first and second apertures.

19. The handle attachment assembly of claim 17, wherein each of said channels further comprises:

a bottom wall having first and second opposed ends, said first sidewall being adjacent to said bottom wall first end, and said second sidewall being adjacent to said bottom wall second end.

20. The handle assembly of claim 19, wherein said first sidewall and said bottom wall first end form an included angle that is greater than 90°

and less than 180°

.

21. A cutting blade for a lawnmower, said cutting blade having a longitudinal axis, comprising:

a lead cutting edge disposed near one end of said blade;

a trailing lift edge disposed opposite to at least a portion of said cutting edge; and

an outer blade edge at the end of said blade between said cutting edge and said lift edge;

wherein a portion of the outer blade edge between the cutting edge and the blade longitudinal axis forms an included angle with said longitudinal axis taken across said blade that is greater than 90°

, and wherein said outer blade edge is non-linear.

22. The cutting blade of claim 21, wherein said outer blade edge is substantially V-shaped.

23. Apparatus for mounting a removable battery to a lawnmower, comprising:

a removable battery having at least one projection extending from a side surface of said battery;

at least one groove formed in said lawnmower and having a longitudinal axis that receives said projection, said groove including

a first tapered section having a first set of sidewalls, at least one of said sidewalls forming a non-parallel first angle with said longitudinal axis; and

a second tapered section adjacent to said first tapered section having a second set of sidewalls, at least one of said second sidewalls forming a non-parallel second angle with said longitudinal axis.

24. The apparatus of claim 23, wherein

said first angle is between 0°

to 5°

; and

said second angle is between 1°

to 45°

.

25. The apparatus of claim 23, further comprising:

a third tapered section adjacent to said second tapered section having a third set of sidewalls, at least one of said third sidewalls forming a non-parallel third angle with said longitudinal axis.

26. The apparatus of claim 25, where said third angle is between 0°

and 5°

.

27. The apparatus of claim 23, further comprising:

a first electrical connector affixed to said battery; and

a second electrical connector affixed to said lawnmower that engages said first electrical connector.

28. A safety interlock for a lawnmower, said lawnmower having a chassis that includes a sidewall, comprising:

a magnetically-responsive switch disposed on said chassis on a first side of said sidewall; and

a removable attachment, including

means for connecting said attachment to said chassis; and

a magnet disposed on said attachment and on an opposite second side of said chassis sidewall;

whereby said magnetically-responsive switch is engaged in response to said magnet when said attachment is connected to said chassis.

29. The safety interlock of claim 28, wherein switch is a reed switch.

30. The safety interlock of claim 28, wherein said removable attachment is a side discharge chute.

31. The safety interlock of claim 28, wherein said removable attachment is a mulching cover.

32. The safety interlock of claim 28, wherein said removable attachment is a bagging attachment.

33. A battery-powered lawnmower having a chassis, comprising:

a height adjustment apparatus that adjusts the height of said lawnmower chassis, including;

a first wheel axle having first and second ends;

a first pivot arm, interconnected with said first end of said first axle, and having a first pivot interconnected with said chassis;

a second pivot arm, interconnected with said second end of said first axle, having a second pivot interconnected with said chassis;

a second wheel axle having first and second ends;

a third pivot arm, interconnected with said first end of said second axle, having a third pivot interconnected with said chassis;

a fourth pivot arm, interconnected with said second end of said second axle, having a fourth pivot interconnected with said chassis;

means for pivoting said first pivot arm about its first pivot;

link means for pivoting said third pivot arm about its third pivot in response to the pivoting of said first pivot arm;

whereby the pivoting of said first pivot arm by said pivoting means rotates said first wheel axle to thereby pivot said second pivot arm about said second pivot;

whereby the pivoting of said first pivot arm by said pivoting means causes said link means to pivot said third pivot arm about its third pivot;

whereby the pivoting of said third pivot arm by said link means rotates said second wheel axle to pivot said fourth pivot arm about said fourth pivot, thereby adjusting the height of said lawnmower chassis;

a control system, including;

a lawnmower handle having a first end interconnected with said lawnmower chassis, and having an opposed second handle end disposed away from said chassis;

a deadman control interconnected with said second end of said handle, said deadman control including a movable member that is held by an operator during operation of said lawnmower, and that is released by said operator to stop said lawnmower;

means for stopping said lawnmower upon the occurrence of at least one predetermined condition;

means for restarting said lawnmower after said lawnmower has been stopped by said stopping means, by releasing said movable member and by thereafter moving said movable member;

a safety device, including;

a removable battery;

at least one electrical connector interconnected with said chassis;

a removable key, including

at least one electrically conductive member that engages said electrical connector to allow said lawnmower to operate;

an engagement member that causes said battery and said key to engage each other, whereby the removal of said battery also disengages said electrically conductive member from said electrical conductor;

a handle attachment assembly, including;

at least one channel affixed to said lawnmower chassis, including;

a first sidewall;

a second sidewall that is non-parallel to said first sidewall;

said first end of said lawnmower handle being received in said channel, wherein the shape of an outer surface of said handle first end corresponds to the shape of said channel; and

means for attaching said handle first end to said chassis;

a cutting blade having a longitudinal axis, comprising;

a lead cutting edge disposed near an end of said blade;

a trailing lift edge disposed opposite to at least a portion of said cutting edge;

an outer blade edge at the end of said blade between said cutting edge and said lift edge;

wherein a portion of the outer blade edge between the cutting edge and the blade longitudinal axis forms an included angle with said longitudinal axis taken across said blade that is greater than 90°

, and wherein said outer blade edge is non-linear;

apparatus for mounting said removable battery, comprising;

at least one projection extending from a side surface of said battery;

at least one groove formed in said lawnmower chassis and having a longitudinal axis that receives said projection, said groove including

a first tapered section having a first set of sidewalls, at least one of said sidewalls forming a first angle with said longitudinal axis; and

a second tapered section adjacent to said first tapered section having a second set of sidewalls, at least one of said second sidewalls forming a second angle with said longitudinal axis.

34. A control system for a battery-powered lawnmower, comprising:

a lawnmower handle having a first end interconnected with a chassis of said lawnmower, and having an opposed second handle end disposed away from said chassis;

a deadman control interconnected with said second end of said handle, said deadman control including a movable member that is held by an operator during operation of said lawnmower, and that is released by said operator to stop said lawnmower;

means for stopping said lawnmower upon the occurrence of at least one predetermined condition;

means for momentarily disabling said stopping means for a preset time after the occurrence of said predetermined condition; and

means for restarting said lawnmower after said lawnmower has been stopped by said stopping means, by releasing said movable member and by thereafter moving said movable member.

35. A control system for a battery-powered lawnmower, comprising:

a lawnmower handle having a first end interconnected with a chassis of said lawnmower, and having an opposed second handle end disposed away from said chassis;

a deadman control interconnected with said second end of said handle, said deadman control including a movable member that is held by an operator during operation of said lawnmower, and that is released by said operator to stop said lawnmower;

means for stopping said lawnmower upon the occurrence of at least one predetermined condition, said at least one predetermined condition including

a first overcurrent condition wherein the current in said lawnmower exceeds a first level;

a second overcurrent condition wherein the current in said lawnmower exceeds a second level that is greater than said first level; and

means for restarting said lawnmower after said lawnmower has been stopped by said stopping means, by releasing said movable member and by thereafter moving said movable member.

36. The control system of claim 35, further comprising:

means for delaying the stopping of said lawnmower by said stopping means when said second overcurrent condition is sensed during the staring of said lawnmower.

37. The control system of claim 35, wherein

said first level is between 32 to 38 amps;

and

said second level is between 50 to 60 amps.

38. A safety device for a battery-powered lawnmower, said lawnmower having a chassis and a motor, said safety device comprising:

a removable battery;

an electrical circuit that provides power from said battery to said motor; and

a removable key that permits power to be supplied from said battery to said motor, said key also engaging said battery such that removal of said battery also causes the removal of said key and said battery cannot be removed without removing said key, and such that said key may be removed without removing said battery.