BATTERY PACK, POWER TOOL, AND CHARGER WITH INDUCTIVE COUPLING

Abstract

A battery pack that makes a power tool easier to handle has a first element for a detachable mechanical and electrical coupling to a power tool and a second element by way of which an inductive coupling with a charger can be made.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The single figure of the drawings is a view showing a battery pack, a power tool and a charger with an inductive coupling in accordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the drawing, as an example of a power tool, a power screwdriver 1 is shown, to that handle 2 of which the battery pack 3 is coupled in the lower region of the handle. Means for mechanical and electrical detachable coupling between the battery pack 3 and the handle 2 of the power tool 1 are indicated in the drawing by reference numeral 4. No attempt will be made to describe this coupling means 4 in detail, since such coupling means are well known in the prior art, for instance from the reference cited at the outset, EP 1 076 370 B1. These coupling means 4 are designed such that the battery pack 3 can be disconnected from the power tool 1 in order to replace the battery pack with another battery pack.

The side 5 of the battery pack 3 facing away from the handle 2 of the power tool 1 is preferably embodied such that it is suitable as a base for the power tool 1, with the battery pack 3 coupled to the power tool.

For charging the battery pack 3, the power tool 1, together with the battery pack 3 coupled to it, is inserted into a charger 6. However, the battery pack 3 may also be disconnected from the power tool 1 and placed in the charger 6 for charging. The battery pack 3 and the charger 6 are embodied such that the charging of the battery pack 3 is effected via an inductive coupling between the battery pack 3 and the charger 6. For that purpose, there is no need for special electrical contacting means to be present on the battery pack 3 and on the charger 6. The charger 6 merely has a receiving shell 7 for the battery pack 3.

The battery pack 3 may contain NiCd or NiMH or Li-ion cells. Li-ion cells have the advantage that their weight relative to the energy content is less than for other battery types.

The inductive coupling is effected via a transformer, whose iron core is split into two parts. The first part 8 of the iron core is located in the battery pack 3, and the second part 9 of the iron core, complementary to the first part, is disposed in the charger 6. At least one primary winding 10 is applied to the second part 9 of the iron core in the charger 6. The first part 8 of the iron core in the battery pack 3 has at least one secondary winding 11.

If the battery pack 3 is now placed in the receiving shell 7 of the charger 6, an inductive coupling is effected between the primary winding 10 and the secondary winding 11 by way of the two parts 8 and 9 of the iron core of the transformer. With the energy transferred from the primary winding 10 in the charger 6 to the secondary winding 11 in the battery pack 3, the battery cells in the battery pack 3 can then be charged. The electrical triggering of the battery cells and the electronics for regulating charging will not be described in detail here, because versions from the prior art can be used for the purpose.

Because one part 9 of the iron core is accommodated in the battery pack 3, specifically in the vicinity of the base 5 facing away from the handle 2, the weight of the battery pack 3 is increased; consequently the center of gravity of the entire arrangement, comprising the power tool 1 and the battery pack 3, is shifted into the handle 2. This improves the balance of the power tool in use. Moreover, with the battery pack 3 coupled to it, the power tool has greater stability when the power tool 1 is set down on the base 5 of the battery pack 3 in the charger 6 or elsewhere.

The number of windings of the secondary winding 11 in the battery pack 3 is oriented to the number of battery cells; in other words, it depends on the rated voltage of the battery pack 3. The number of windings of the primary winding 10 in the charger 6 is independent of the rated voltage of the battery pack 3. With one and the same charger 6, battery packs having various rated voltages can thus be charged, without requiring an adaptation to the rated voltage of whichever battery pack is to be recharged to be made in the charger by means of an electronic charging system.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the type described above.

While the invention has been illustrated and described as embodied in a battery pack, power tool, and charger with inductive coupling, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention.

Claims

1. A battery pack, comprising first means configured for detachable mechanical and electrical coupling to a power tool; and second means configured for an inductive coupling with a charger.

2. A battery pack as defined in claim 1, wherein said second means have a part with at least one secondary winding of a transformer of an iron core located in the battery pack so that on being inserted into the charger, it couples inductively with a complementary part of the iron core that is located in the charger and has at least one primary winding.

3. A battery pack as defined in claim 1, wherein said second means configured for an inductive coupling with the charger are located in the battery pack on a side diametrically opposite to said first means configured for coupling to the power tool.

4. A battery pack as defined in claim 1, further comprising a base, said second means configured for an inductive coupling with the charger being located in a vicinity of said base.

5. A power tool, comprising a battery pack having first means configured for detachable mechanical and electrical coupling to a power tool, and second means configured for an inductive coupling with a charger.

6. A power tool as defined in claim 5, wherein said second means configured for an inductive coupling with the charger is configured so that they provide the inductive coupling with the charger without disconnecting the battery pack form the power tool.

7. A power tool as defined in claim 5, further comprising a handle having a lower end, said means configured for detachable mechanical and electrical coupling of the battery pack to the power tool being provided on said lower end of said handle.

8. A charger inductively coupleable to a battery pack that is mechanically and electrically coupleable to first means of a power tool, said charger being configured for an inductive coupling with second means of the battery pack.

9. A charger as defined in claim 8, further comprising one part with at least one primary winding of a transformer of an iron core that upon insertion of the battery pack couples inductively with a complementary part located in the battery pack of the iron core, which complementary part has at least one secondary winding, and said complementary part and said secondary winding form said second means.