Portable self-contained electric power tool

• US 7,592,773 B2
• Filed: 11/18/2004
• Issued: 09/22/2009
• Est. Priority Date: 11/20/2003
• Status: Expired due to Fees

• Current Assignee: PELLENC SA
• Original Assignee: PELLENC SA
• Inventors: Pellenc, Roger
• Primary Examiner(s): Ullah; Akm E
• Assistant Examiner(s): Tran; Nguyen
• Application Number:
  US10/579,917
• Publication Number:
  US 20070148539A1
• Time in Patent Office: 1,769 Days
• Field of Search: 320/107, 320/108, 320/110, 320/111, 320/112, 320/113, 320/114
• US Class Current: 320/114
• CPC Class Codes: A01G 3/037 the driving means being an electric motor
• CPC Class Codes: H02J 7/0013 acting upon several batteries simultaneously or sequentially H02J7/1423 takes precedence
• CPC Class Codes: H02J 7/0042 characterised by the mechanical construction
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

A portable self-contained electric power tool unit, includes at least three distinct sub-assemblies. The tool is characterised in that the second sub-assembly (3) may be carried by the user and includes a lithium-ion or lithium-polymer electrochemical battery (5) formed by combination of more than four cells (6) in series, each cell being made of one or several elements in parallel and a control and operating module (7) for the battery (5), guaranteeing a maximum battery capacity over time in a controlled manner and an optimal use of the tool. The first sub-assembly (2), during operation thereof, is subject to control by a current-limiting system (8), for preserving the lithium-ion or lithium-polymer battery (5) from which the above draws energy and the third sub-assembly (4) has at least one source of electrical supply, the voltage and current of which are suitable for the recharging of the lithium-ion or lithium-polymer battery (5).

Claims

1. A portable self-contained electrical power tool assembly, comprising:

a first subassembly forming an electrical actuator and generating the mechanical action of the tool;

a second subassembly forming an electric energy source and comprising essentially a rechargeable electrochemical battery; and

a third subassembly forming a charger adapted to carry out controlled recharging of the battery, wherein;

the second subassembly (3) is portable by an operator and is constituted by a lithium ion or lithium polymer electrochemical battery (5) formed by association of more than four cells (6) in series, each cell being comprised by one or several elements in parallel and, the second subassembly (3) is also constituted by an electronic command and control module (7) for the battery (5), in the form of an electronic device located in immediate adjacency to said battery (5) and ensuring over time and in a controlled manner a maximum capacity of the battery and an optimum use of the tool;

the first subassembly (2) is subjected during its operation to control by a system (8) of current limitation adapted to reserve the lithium ion or lithium polymer electrochemical battery (5) from which it draws energy;

the third subassembly (4) comprises at least a source of electrical supply whose voltage and current are suitable to recharging the lithium ion or lithium polymer battery (5),

the electronic command and control module (7) of the battery (5) fulfilling at least tasks i) to v) as follows;

i) management of charge,

ii) management of discharge,

iii) balancing the charge of each cell (6),

iv) protection in discharge of the battery (5) as to excess current during utilization of the tool,

v) management during storage, and

vi) management of diagnostics,

wherein when the tool assembly is not charging and has not been used for a predetermined period the digital processing unit (9) automatically performs a task of management of storage which comprises verifying whether the residual capacity of the battery (5) is greater or not than the storage capacity predetermined by the manufacturer or lithium ion or lithium polymer elements and, if the residual capacity is substantially superior to the storage capacity, in triggering by the digital processing unit (9) an automatic discharge of the battery.

2. The electrical tool assembly according to claim 1, wherein electronic control and command module (7) of the battery (5) of the second subassembly (3) is present in the form of an electronic card and comprises at least one digital processing unit (9), comprising a microprocessor, a microcontroller, or a digital signal processor, associated with a memory and with annexed circuits, adapted together to performs in addition to tasks i) to v), at least one of the following tasks:

evaluation and display of the capacity of the battery (5),

management of alarms, and

management and transmission of collected information.

3. The electrical tool assembly according to claim 2, wherein for the accomplishment of the tasks of management of the charge, of management of the discharge, balancing of the charge of each cell (6), evaluation and display of the capacity of the battery (5), the command and control module (7) permanently uses the values of measurement of the voltage of each cell (6) comprising the battery (5).

4. The electrical tool assembly according to claim 3, wherein for a battery (5) formed of n cells (6) in series, the values of measurement of the voltage of each cell (6) are provided by an electronic acquisition channel (10) constituted principally of n identical analog modules (11) corresponding to the n cells (6), mounted respectively at terminals of the n cells (6) of the battery (5) and adapted to measure a voltage of the respectively corresponding cell (6), the values of voltage measured by each of the n modules (11) being then routed, one after the other, by at least one analog multiplexer (12) and after amplification by a suitable circuit (13) toward an analog/digital input converter (9′

) of the digital processing unit (9) forming a portion of the command and control module (7).

5. The electrical tool assembly according to claim 4, wherein the analog modules (11) for measurement of voltage perform respectively for each cell (6) a subtraction between the voltage measured at its positive terminal and the voltage measured at its negative terminal, this by a differential electronic assembly with an operational amplifier (11′

) using resistances (11″

) for resistive input elements.

6. The electrical tool assembly according to claim 5, wherein the electronic differential assembly with operational amplifier (11′

) of each voltage measuring module (11) comprises resistances or resistive input elements (11″

) of an impedance of about or greater than 1 Mohm so as to obtain very low loss currents less than 1/20000^th per hour of the total capacity of the battery (5).

7. The electrical tool assembly according to claim 3, wherein the values of measurement of the voltage of each cell (6) are delivered with a precision of measurement of at least 50 mV.

8. The electrical tool assembly according to claim 7, wherein the precision of measurement of the voltage of at least 50 mV is obtained by calibration during production of the electronic card of the command and control module of the battery (7).

9. The electrical tool assembly according to claim 8, wherein the calibration during manufacture of the electronic card comprises introducing by programming into the digital processing unit (9), for each module of voltage measurement (11), parameters for correcting errors as a function of the measurement of one or several very precise reference voltages, that are substituted for this calibrating operation for the normal voltages measured at the terminals of each cell (6).

10. The electrical tool assembly according to claim 2, wherein the task of balancing the charge of the cells (6) relative to each other is managed by the digital processing unit (9) which controls based on the values of measurement of voltage of each cell (6), a development of the charge current by dissipater circuits based on electronic switches (14) associated with resistive elements (14′

).

11. The electrical tool assembly according to claim 2, wherein the task of managing the discharge comprises continuously scrutinizing the voltage data of each cell (6) by the digital processing unit (9), in interrupting the discharge when the digital processing unit (9) detects that one of the voltages of the cell (6) has reached the minimum discharge threshold set by the producer of lithium ion or lithium polymer elements and in cutting the discharge by deactivating a switching component (15) of the discharge, thereby leading to stopping the tool (2) and by activating a sonic or visual alarm.

12. The electrical tool assembly according to claim 3, wherein the tasks of managing the charge, of evaluating and displaying the capacity of the battery (5) and of protection from overvoltage during discharge, are managed continuously by the digital processing unit (9) by an analog electronic circuit (16) for measurement of the current of the charge and discharge of the battery (15).

13. The electrical tool assembly according to claim 12, wherein during the task of managing the charge, while the third subassembly forming a charger (4) is connected to the second subassembly (3) at the electronic card of the command and control module (7) of the battery (5), the end of the charge is obtained by opening the switching component of the charge (17) which is controlled by the digital processing unit (9) when said unit (9) detects by means of the digital electronic circuit (16) for measuring the charge and discharge current, a drop in the charge current to a predetermined threshold, for example 50 mA, for the battery (5) or when the temperature of the battery (5) exceeds a permitted limit value, or that the charging is prolonged during a time greater than a given fraction of the theoretical charge time.

14. The electrical tool assembly according to claim 12, wherein the task of evaluation and display of the capacity of the battery (5) is managed by the digital processing unit (9) computing said capacity by taking into account continuously, during charge and during use of the tool, information as to the instantaneous current of the charge and discharge of the battery (5) delivered by the analog electronic circuit for measuring the current of charge and discharge (16) or the values of measurement of voltage of each cell (6) and, for more precise computation, their known mean internal resistance.

15. The electrical tool assembly according to claim 2, wherein the task of protection from over-current during the discharge of the battery (5) during use of the tool, adapted to preserve the lithium ion or lithium polymer battery from premature aging or from exaggerated heating, comprises either in cutting the discharge current in the case of very large impulsional exceeding of the maximum discharge current for the battery (5) or by exceeding the maximum limit temperature permitted for this latter, or by limiting the discharge current as a function of the energy consumed by the tool during a certain running time, given that the value of the energy of the running time is predetermined experimentally as a function of the tool, of it use and of the desired lifetime for the lithium ion or lithium polymer battery (5) forming a portion of the second subassembly (3).

16. The electrical tool assembly according to claim 15, wherein the limitation of discharge current is managed by the unit (9) for digital processing by applying a command for modulation of impulse width (MLI), generated either directly by said unit (9), or by a specialized component, or by a piloting stage (18), with a switching component of the discharge (15) provided in the form of a component of a MOSFET channel N type.

17. The electrical tool assembly according to claim 2, wherein with the help of resistive circuits (14, 14′

) connected in parallel with each cell (6), until the storage capacity is reached, and then stopping all the electronic circuits while placing the processing unit (9) is standby in low consumption mode and, if the capacity is below the storage capacity, triggering by the digital processing unit (9) a sonic and/or visual alarm.

18. The electrical tool assembly according to claim 2, wherein the digital processing unit (9) is adapted to detect the connection of the charger (4) under voltage to the battery (5) by a voltage measurement by the command and control module (7) at at least one of the terminals (20) of the second subassembly (3) adapted to be connected to said charger (4).

19. The electrical tool assembly according to claim 18, wherein the function of detection of the connection of the charger (4) under voltage to the battery (5) is carried out by a particular suitable measuring circuit (19), permitting, while the tool is stored in nonuse phase, by detecting the instant at which at least one cell (6) achieves the minimum voltage set by the manufacturer, thereby to trigger an automatic recharge of the battery (5).

20. The electrical tool assembly according to claim 18, wherein when the command and control module (7) detects an excessive or insufficient voltage of the charger (4) at the corresponding connection terminals (20) of the second subassembly (3), the digital processing unit (9) which uses this information commands the stopping of charging and triggers a sonic and/or visual alarm.

21. The electrical tool assembly according to claim 2, wherein the task of managing the information and diagnostics consists in storing in the memory of the digital process unit (9) information acquired during the use of the tool including at least one of:

a number of recharges,

a total of the hours of use of the tool,

a development of the capacity of the battery (5) with time, or

a mean energy consumed by the tool,

this information being adapted to be transmitted by means of a wire connection (23), radio frequency of infrared toward a separate exploitation terminal of the personal computer type, an electronic personal assistant, GSM, or the information can be transmitted via Internet.

22. The electrical tool assembly according to claim 2, wherein the command and control module (7) of the battery (5) forming a portion of the second subassembly (3) forming a source of rechargeable electrical energy is associated with the electronic command and control module of the actuator (2) on the same electronic card, with use of the same digital processing unit (9).

23. The electrical tool assembly according to claim 1, wherein the electronic command and control module (7) of the battery (5) comprises for each cell (6) redundant security circuits for stopping charging (21), adapted to control each individually, in case of overvoltage of a cell (6), the general stopping of the charge by deactivating directly a switching component (17) for the charge without disturbing the digital processing unit (9).

24. The electrical tool assembly according to claim 12, wherein the electronic command and control module (7) comprises a redundant circuit for stopping discharge (21′

), adapted to control the stopping of discharge in the case of detection of a discharge current equal to or greater than a maximum admissible value for the battery (5) by the analog electronic measuring circuit (16), by directly deactivating the switching component (15) of the discharge without disturbing the digital processing unit (9).

25. The electrical tool assembly according to claim 1, wherein the third subassembly (4) forming a charger adapted to recharge the lithium ion or lithium polymer battery (5) generates a voltage with a precision of about 0.5% and a regulated current, obtained by a specialized circuit for regulation of voltage and current.

26. The electrical tool assembly according to claim 1, wherein each functional subassembly (2, 3 and 4) is mounted in a protective housing and/or a grippable housing, which can be connected together two by two by flexible deconnectable cables (22, 22′

) for the transfer of energy and the transmission of command and/or control signals between said subassemblies (2, 3, 4).

27. The electrical tool assembly according to claim 1, wherein the electrical tool assembly is pruning shears, a chainsaw, a fruit collecting tool, a lawnmower with wires, or a jackhammer.