On-board charging system for electric lawn mower

• US 5,727,372 A
• Filed: 05/30/1996
• Issued: 03/17/1998
• Est. Priority Date: 05/30/1996
• Status: Expired due to Term

• Current Assignee: Toro Company (Toro)
• Original Assignee: Toro Company (Toro)
• Inventors: Kanitz, Allan Dale, Kakuk, Jay Jeffrey
• Primary Examiner(s): Melius, Terry Lee
• Assistant Examiner(s): PEZZUTO, ROBERT ERIC
• Application Number:
  US08/655,732
• Time in Patent Office: 656 Days
• Field of Search: 56/6, 56/7, 56/10.2 A, 56/10.2 R, 56/11.9, 56/11.1, 56/10.5, 56/17.5, 56/DIG. 15, 320/2, 364/424, 364/425, 364/426, 364/429
• US Class Current: 56/11.9
• CPC Class Codes: A01D 34/78 electric
• CPC Class Codes: A01D 69/02 electric

Abstract

A self-contained apparatus for charging a battery on an electrically powered turf maintenance vehicle. The charger includes an AC to DC converter for accepting a source of AC power and providing a DC voltage, a sensor for measuring the voltage level of the battery, and a controller for determining the voltage of the battery and for changing the charge rate of the battery. The apparatus also includes visual indicators for warning an operator of normal and abnormal charge conditions of the battery, as well as the remaining charge of the battery. Further, the controller uses a plurality of timers for determining the length of charge times and comparing the values of the timers with count values, wherein if the values exceed the count values, then a visual indicator is lit and charging is terminated. The apparatus is mounted in a box-type shell on-board the turf maintenance vehicle.

Claims

1. A self-contained battery charger apparatus for charging a battery for an electrically powered turf mower, the battery having a voltage, comprising:

a) an AC to DC converter for accepting a source of AC power and providing a DC current source output;

b) a regulator device operatively connected between said converter for receiving said current source output and the battery, wherein said regulator device is responsive to control signals for selectively providing said current source output to the battery;

c) first sensor means for measuring the voltage of the battery and providing a first voltage signal;

d) second sensor means for measuring the current delivered to the battery and providing a second voltage signal; and

e) controller means, operatively connected to said first and second sensor means and said regulator device, for determining the voltage of the battery from said first voltage signal, for determining the current provided to the battery from said second voltage signal, and for providing a pulse width modulated control signal to said regulator device to provide a periodic constant current level to the battery based on said determined battery voltage and current.

2. The apparatus of claim 1, further comprising first visual indicator means, operatively connected to said controller means, for alerting an operator of normal and abnormal charge conditions of the battery.

3. The apparatus of claim 2, wherein said controller means includes means for storing one or more predetermined values and a plurality of timers for determining the lengths of charge times and comparing said determined lengths of charge times with one or more of said predetermined values, wherein if said determined lengths of charge times exceed said predetermined values, then a first visual indicator is lit.

4. The apparatus of claim 1, further comprising second visual indicator means, operatively connected to the battery, for alerting an operator of the remaining battery charge.

5. The apparatus of claim 1, further comprising a shell for containing said converter, said regulator device, said first and second sensor means, and said controller means on-board the turf mower.

6. The apparatus of claim 5, wherein said converter, said regulator device, said first and second sensor means, and said controller means are potted within said shell, whereby the battery charger is sealed from the environment.

7. The apparatus of claim 6, wherein said regulator device, said first and second sensor means, and said controller means are located within a single shell.

8. The apparatus of claim 6, wherein said regulator device, said first and second sensor means, and said controller means are located within a first shell and wherein said converter means are located within a second shell.

9. The apparatus of claim 1, wherein said controller means generates a pulse width modulated control signal for said regulator means, whereby the battery charger generates a smaller amount of thermal energy than a linear mode charger device, wherein potting and encapsulation is allowed.

10. An on-board battery charger apparatus, for charging a battery for an electrically powered turf mower, comprising:

a) an electric turf mower, said turf mower including;

i) a frame;

ii) a battery, said battery including a voltage;

iii) a cutting member, rotatably connected to said frame and arranged and configured for cutting turf;

iv) an electric motor, operatively connected to said frame, said battery, and said cutting member, for rotating said cutting member;

b) a single shell cooperatively mounted to said turf mower;

c) an AC to DC converter for accepting a source of AC power and providing a current source output;

d) a regulator device operatively connected between said converter for receiving said current source output and said battery, wherein said regulator device is responsive to control signals for selectively providing said current source output to said battery;

e) first sensor means for measuring the voltage of said battery and providing a first voltage signal;

f) second sensor means for measuring the current delivered to said battery and providing a second voltage signal;

g) controller means, operatively connected to said first and second sensor means and said regulator device, for determining the voltage of said battery from said first voltage signal, for determining the current provided to said battery from said second voltage signal, and for providing a control signal to said regulator device to provide a periodic constant current level to said battery based on said determined battery voltage and current; and

h) wherein said controller means, said first and second sensor means, and said regulator means are located and potted entirely within said shell.

11. The apparatus of claim 10, further comprising first visual indicator means, operatively connected to said controller means, for alerting an operator of normal and abnormal charge conditions of said battery.

12. The apparatus of claim 10, wherein said controller means includes a plurality of timers for determining the lengths of charge times and comparing said determined lengths of charge times with values stored in a memory location, wherein if said determined lengths of the charge times exceed said stored values, then a first visual indicator is lit.

13. The apparatus of claim 10, further comprising second visual indicator means, operatively connected to said battery, for alerting an operator of the remaining battery charge.

14. A method of insulating against electrical shock and fire in a self-contained battery charger apparatus for charging a battery for an electrically powered turf mower, wherein the battery charger includes an isolation transformer and electrical components which are connected together with electrical conductors, comprising the steps of:

a) enclosing an isolation, step-down transformer in a first flame retardant enclosure located within the mower, wherein said isolation transformer provides a first insulation layer;

b) enclosing in a second flame retardant enclosure battery charger electronics, said battery charger electronics generating a charging current output with a power;

c) insulating an electrical conductor between said transformer and said battery charger electronics;

d) fusing the power output of said battery charger electronics to the battery below a predetermined level; and

e) providing a second insulation layer on the mower, wherein said first and second layers provide double insulation for electrical shock.

15. The method of claim 14, wherein:

a) said first and second enclosures are constructed of plastic;

b) said fuse limits the power output below 100 VA; and

c) said second insulation layer on the mower is a plastic shell encompassing the top and sides of the mower.

16. An on-board battery charger apparatus for charging a battery for an electrically powered turf mower, comprising:

a) an electric turf mower, said turf mower including;

i) a frame;

ii) a battery, said battery including a voltage;

iii) a cutting member, rotatably connected to said frame and arranged and configured for cutting turf;

iv) an electric motor, operatively connected to said frame, said battery, and said cutting member, for rotating said cutting member;

b) a single shell cooperatively mounted to said turf mower;

c) an AC to DC converter for accepting a source of AC power and providing a current source output;

d) a regulator device operatively connected between said converter for receiving said current source output and said battery, wherein said regulator device is responsive to control signals for selectively providing said current source output to said battery;

e) first sensor means for measuring the voltage of said battery and providing a first voltage signal;

f) second sensor means for measuring the current delivered to said battery and providing a second voltage signal;

g) controller means, operatively connected to said first and second sensor means and said regulator device, for determining the voltage of said battery from said first voltage signal, for determining the current provided to said battery from said second voltage signal, and for providing a control signal to said regulator device to provide a periodic constant current level to said battery based on said determined battery voltage and current; and

h) wherein said controller means, said first and second sensor means, and said regulator means are located and potted entirely within said shell, whereby the turf mower complies with electrical shock and fire standards of the UL Standards for Safety, UL 1447 and UL 1012 in effect as of May 31, 1996.

17. The apparatus of claim 16, further comprising first visual indicator means, operatively connected to said controller means, for alerting an operator of normal and abnormal charge conditions of said battery.

18. The apparatus of claim 16, wherein said controller means includes a plurality of timers for determining the measured lengths of charge times and comparing the measured lengths of charge times with values stored in a memory location, wherein if the measured lengths of charge times exceed the stored values, then a first visual indicator is lit.

19. The apparatus of claim 16, further comprising second visual indicator means, operatively connected to said battery, for alerting an operator of the remaining battery charge.