Interface between battery and electrical equipment

Abstract

An interface (30) between a battery and an electrical device, the interface (30) comprising: a male terminal (24) and a female terminal (26), the female terminal being configured to receive the male terminal (24); the female terminal (26) having a female contact (36) of a conductive material, and the male terminal (24) having a male contact (32) of a conductive material; wherein at least one of the female contact (36) and the male contact (32) is elastically deformable, so that the insertion of the male terminal (24) into the female terminal (26) provides a face-to-face contact area (40), in which the male contact (32) and the female contact (36) fit each other.

Description

Technical Field

[0001] The present invention relates to battery powered devices and in particular to the electrical interface between a battery and a device. Background Art

[0002] As battery technology has advanced, many devices that were traditionally powered by 'mains' electricity or small internal combustion engines are now powered by batteries. For convenience, the batteries are often configured to be quickly removed and replaced with rechargeable batteries to extend the operating time of the device. This is usually achieved via a battery interface that has male terminals that plug into female terminals to establish an electrical connection.

[0003] To ensure that the electrical connection is maintained during use, the male terminal is inserted into the female terminal with an interference fit. Figures 1A and 1B depict this type of prior art battery interface. Figure 1A shows the female side 10 of the interface, which is used to receive the male side 2 shown in Figure 1B. The female side 10 has a housing 22 that accommodates a series of adjacent female contacts 12, each female contact having a pair of opposing conductive arms 16 and 18 that are offset toward each other so that they contact at the bend line 20. The male side 2 has a series of male contacts 14 in the form of flat spade-shaped terminals. The outer surfaces of the opposing arms 16 and 18 of the corresponding female contacts 12 guide the male contacts 14 to the bend line 20. Here, when the male contact 14 slides between the arms 16 and 18, the insertion force squeezes the two arms apart to fully engage the female contact 12.

[0004] The inward bias on arms 16 and 18 grips the male terminal 14 to ensure that the electrical connection is maintained. However, the physical contact area between the terminal and the contact is only along their respective bend lines 20. This is a relatively small surface area and can result in high resistance, especially when the circuit is carrying high current. In some cases, the interface between a plug-in battery and a DC motor carries relatively high current, and therefore the resistive losses at the electrical interface are large.

[0005] In view of these issues, it would be beneficial to provide an interface between a battery and an electrical device in which the male and female terminals have relatively low resistive losses. Summary of the invention

[0006] The present invention discloses an interface between a battery and an electrical device, the interface comprising: a male terminal and a female terminal configured to receive the male terminal; the female terminal has a female contact of a conductive material, and the male terminal has a male contact of a conductive material; wherein at least one of the female contact and the male contact is elastically deformable, so that the insertion of the male terminal into the female terminal provides a face-to-face contact area in which the male contact and the female contact fit each other.

[0007] On the other hand, an electrical device having an interface to a battery is disclosed, the interface comprising: a male terminal and a female terminal configured to receive the male terminal; the female terminal having a female contact of a conductive material, and the male terminal having a male contact of a conductive material; wherein at least one of the female contact and the male contact is elastically deformable so that insertion of the male terminal into the female terminal provides a face-to-face contact area in which the male contact and the female contact fit into each other.

[0008] Preferably, the female terminal has a recess for receiving the male terminal, and the female contact has elastically deformable portions on at least two opposite sides of the recess.

[0009] Preferably, the male terminal has a housing with an opening through which the male contact extends, and the male contact is mounted in the housing for movement within the opening. Preferably, the opening is planar and the movement is in a direction parallel to the plane of the opening. In a further preferred form, the male contact is fixed in a direction perpendicular to the plane of the opening.

[0010] In an alternative embodiment, the male contact is elastically deformable.

[0011] Preferably, the elastically deformable portion of the female contact is bent inwardly into the recess before the male terminal is inserted. Preferably, the male contact of the male terminal is cylindrical. Optionally, the male contact has a rectangular cross-section and opposing flat surfaces to provide an area of ​​face-to-face contact with the female contact. Optionally, the male contact has a recessed portion to provide an area of ​​face-to-face contact with the female contact.

[0012] Preferably, the female contacts are provided by resiliently deformable strips which are held compressively within the recesses such that the strips bend inwardly.

[0013] Preferably, the strip is elongated and extends in the insertion and extraction direction of the male terminal.

[0014] Preferably, the strips extend from an integrally formed cross-member such that the strips are spaced apart along the edge of the cross-member to form a comb-like structure. Optionally, the elastically deformable strips extend between two spaced apart cross-members to form a trapezoidal structure.

[0015] Preferably, the recess has two comb structures such that the cross members of each comb structure are spaced apart and the strips from each comb structure are interleaved.

[0016] Preferably, the cross-members of the comb-like structure are shaped such that the strips are positioned circumferentially around the male terminal.

[0017] Preferably, the cross-member forms a closed ring, such that the strips are bent radially inwards and the male contacts have a circular cross-section smaller than the inner diameter of the ring.

[0018] Preferably, the male contact of the male terminal is cylindrical, or alternatively hourglass-shaped.

[0019] Preferably, the strips are made of copper, silver or a conductive alloy.

[0020] Preferably, during use, the current flowing between the battery and the device is between 40 amps and 400 amps. In a further preferred form, the current flowing between the battery and the device is between 80 amps and 300 amps, or more preferably between 100 amps and 150 amps.

[0021] Preferably, the male contact has a cross section transverse to the insertion direction, the minimum dimension of which is between 3 mm and 20 mm. In a further preferred form, the male contact has a cross section transverse to the insertion direction, the minimum dimension of which is between 8 mm and 12 mm.

[0022] Preferably, the insertion force of the male terminal into the female terminal is between 5 Newtons and 50 Newtons. In a further preferred form, the insertion force of the male terminal into the female terminal is between 15 Newtons and 30 Newtons.

[0023] Preferably, the disassembly force for disengaging the male terminal from the female terminal is between 2 Newtons and 30 Newtons. In a further preferred form, the disassembly force for disengaging the male terminal from the female terminal is between 12 Newtons and 20 Newtons.

[0024] In a particularly preferred form, the battery includes a female terminal.

[0025] In some embodiments, the interface further comprises a spade-type or pin-type male contact and a matching female contact for transmitting an electrical data signal. In a particularly preferred form, the data signal indicates one or more of the following:

[0026] Battery level,

[0027] Battery temperature, and

[0028] Remaining operation time. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Preferred embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0030] 1A and 1B show an interface between a battery and an electrical device according to the prior art;

[0031] Figure 2A A schematic depiction of an electrical connection according to the present invention is shown before the male terminal is inserted into the female terminal.

[0032] Figure 2B Shows Figure 2A Electrical connection to the male terminal.

[0033] Figure 3A Schematic front and side views of two mutually opposing conductive comb structures are shown, the two conductive comb structures are interlaced and compressed and held in a recess of a female terminal;

[0034] Figure 3B Schematically showing mutually opposing strips of a comb-like structure bending inwardly within a recess;

[0035] Figure 4 is a perspective view of a male terminal with a male contact extending through an opening in a housing of the male terminal;

[0036] Figure 5A and Figure 5B They are partial cross-sectional views of the female terminal and the male terminal respectively;

[0037] Figure 6 Schematically depicts an embodiment of a male terminal having an elastically deformable male contact;

[0038] Figure 7 schematically depicts an embodiment of a male contact having an outer surface contoured to engage with a female contact; and

[0039] Figure 8 is a perspective view of a battery powered lawn mower using a battery interface according to the present invention. DETAILED DESCRIPTION

[0040] 1A and 1B show a female terminal 10 and a male terminal 2 of a battery interface according to the prior art. A terminal body 22 provides a series of female contacts 12 for receiving male contacts 14. Each female contact 12 has opposing arms 16 and 18 that are offset from each other so that they abut at a bend line 20 extending the width of the arms 16 and 18.

[0041] The male contact 14 is a simple spade terminal in which the flat spade contact squeezes the arms 16 and 18 apart when inserted into the female contact 12. The electrical connection between the male contact 14 and the female contact 12 is only along the bend line 20. These contact "lines" provide a very small surface area connection between the two contacts. The small area connection can cause resistance, especially when the electrical interface is in a relatively high current circuit. For example, a battery powering a DC motor for a large device such as a lawn mower will require a relatively high current (e.g., above 40 amps), in which case the resistance caused by the thin line of contact 20 between the male terminal 2 and the female terminal 10 is detrimental to the overall efficiency of the device. This in turn reduces the operating time before the battery needs to be replaced or recharged.

[0042] For devices such as leaf blowers, stick vacuum cleaners, etc., the normal "run time" should be long enough to allow the user to complete routine or typical tasks before the battery needs to be recharged. Similarly, the battery should not be too large to ensure that the handheld device is not too heavy during use.

[0043] In view of these problems, there is an urgent need to minimize the electrical losses at the electrical interface between the plug-in battery and the electric drive device. Figure 2A and Figure 2B As shown, for the sake of clarity, the electrical interface according to the present invention is schematically shown. Figure 2A , the electrical interface 30 is shown as the male terminal 24 is disengaged from the female terminal 26. The male terminal 24 has a male contact 32, which is used to be inserted into a recess 34 forming the female terminal 22. The female contact 36 is within the recess 34, providing an inwardly curved conductive surface. The female contact 36 is configured to be elastically deformable, so that placing the male contact 32 into the recess 34 along the insertion direction 28 will cause the female contact 36 to deform, as shown in FIG. Figure 2B As shown. To accommodate the male contact 32, the female contact 36 fits with the outside of the male contact to provide at least one area 40 of face-to-face contact. This face-to-face contact area 40 provides much lower resistance for current flow, especially for high current flow. At the same time, the elastic deformation of the female contact 36 clamps the male contact 32 to keep the male terminal 24 and the female terminal 26 engaged.

[0044] like Figure 4 As shown, the distal end of the male contact 32 has a rounded or chamfered edge to facilitate insertion of the female contact 36. The housing 8 of the male terminal 24 has an opening 68 through which the male contact 32 extends. The opening 68 is larger than the male contact 32 to provide a peripheral gap 38. The male contact 32 is mounted in the housing 8 so that the male contact can move within the opening 68. More specifically, the male contact 32 has limited movement in a direction parallel to the plane of the opening 68 (e.g., see arrow 4), but remains fixed in a direction 6 perpendicular to the plane. This configuration compensates for manufacturing and / or installation errors of the male contact 32 relative to its housing 8. This configuration helps the male contact 32 to be centered within the female contact 36.

[0045] Figure 3A and Figure 3B A convenient technique for providing an arcuate female contact 36 is schematically illustrated. The female contact 36 is provided by a conductive material formed into two mutually opposing comb structures 50 and 52. Each comb structure has a cross member 46 and 48 from which conductive strips 42 and 44 extend, respectively. The comb structures 50 and 52 are brought together so that their conductive strips 42 and 44 are staggered. Figure 5A and Figure 5BAs best shown, the comb structures 50 and 52 are then curled so that the cross-members 46 and 48 form a closed shape, such as a circle. Figure 3B and Figure 5A As shown, the combined comb structures 50 and 52 are held in compression within the recess 34 so that the individual conductive strips 42 and 44 are bent inwardly. The longitudinal direction of each of the conductive strips 42 and 44 is generally aligned with the insertion direction 28 (see Figure 2A ) so that there are no edges or structural obstacles that would hinder the insertion of the male contact 32.

[0046] The arcuate female contact may be formed in other ways. For example, the arcuate male contact may be provided as a single integrally formed comb-like structure, or a trapezoidal structure with transverse elements extending along both sides of adjacent strips. The arcuate male contact may also be provided by multiple cooperating elements or any other structure that provides suitable resilience.

[0047] As shown in FIG5 , another embodiment of an electrical connection 54 is shown. In this embodiment, the male terminal 24 has a male contact 58 that provides an elastically deformable strip 60 around its exterior. The female terminal 26 has a housing 22 that defines a receptacle 34 similar to the previous embodiment. However, the female contact 56 is only a conductive sleeve and cannot be elastically deformed.

[0048] Inserting the male contact 58 into the receptacle 34 in the insertion direction 28 compresses the elastically deformable strips 60 such that the strips engage the inner surfaces of the female contact 56 to provide a face-to-face contact area 40 (not shown).

[0049] Figure 6 Another embodiment of an electrical interface 62 is schematically illustrated, wherein the female terminal 26 is similar in structure to the first embodiment of the electrical connection 30. However, the male terminal 24 has a male contact 64 whose outer surface is shaped to substantially conform to the inner surface of the female contact 36. Providing an hourglass-shaped outer surface 66 on the male contact 64 promotes a larger face-to-face contact area 40 (not shown), wherein the male contact 64 and the female contact 36 are biased into a mutually engaging abutting engagement. This provides a connection with low resistance and a stronger physical retention of the male terminal 24 in the female terminal 26.

[0050] Embodiments of the electrical connection may have additional male contacts in the form of flat spade terminals or round cross-section pins for transmitting data indicating an operating state or parameter of the device or battery. For example, the data may indicate current battery charge, battery temperature, device temperature, and / or remaining operating time.

[0051] The electrical interface described herein is well suited for connection between a plug-in rechargeable battery and a DC motor of a device that draws relatively high current, such as a battery-powered lawn mower. Figure 8 A battery powered lawn mower 80 is shown having one or more rechargeable batteries in a battery compartment 82, but the battery interface is also suitable for devices such as handheld leaf blowers, stick vacuum cleaners, string trimmers, hedge trimmers, etc. For these devices, it may be advantageous to provide female terminals on the battery to reduce the risk of contact with water (when caught in rainy days, etc.). The device may have a variety of batteries. The battery may be a nickel cadmium battery, a nickel metal hydride battery, a lithium ion battery, or a sealed lead acid battery. For this type of device, the rechargeable battery is configured to not only provide an output, but also receive an input recharge current in the range of 40 amps to 400 amps, or preferably between 80 amps and 300 amps, or more preferably between 100 amps and 150 amps.

[0052] Structurally, the applicant's development of these products has shown that the minimum dimension of the cross section of the male contact transverse to the insertion direction 28 should be in the range of 3mm to 20mm, or preferably, the minimum dimension of the cross section of the male contact transverse to the insertion direction is between 8mm and 12mm.

[0053] For example, if the male contact is such as Figure 4 If the cylindrical pin shown is used, the diameter of the cylindrical pin should be between 3 mm and 20 mm. Likewise, the actual insertion force range for the male terminal to be inserted into the female terminal should be in the range of 5 Newtons to 50 Newtons, or preferably, the insertion force of the male terminal into the female terminal is between 15 Newtons to 30 Newtons. These insertion forces used with contacts having dimensions in the ranges discussed above provide appropriately low contact resistance.

[0054] When removing the male terminal from the female terminal, the extraction force should be in the range of 2 Newtons to 30 Newtons, or preferably between 12 Newtons and 20 Newtons, so that the battery remains on the device during normal operation, but it is not difficult for the user to manually remove the male terminal.

[0055] As the complexity of the above devices increases, the need for data communication terminals at the electrical interface in addition to high current male and female terminals is also increasing. The data terminals can transmit signals indicating battery charge, battery temperature, device temperature, remaining operating time or other information to a user display on the device. Given that the current levels are much lower and resistance is not a significant issue, the data terminals can be provided by traditional blade type terminals or pin type terminals and sockets.

[0056] The present invention has been described herein by way of example only. Those skilled in the art will readily appreciate and appreciate numerous variations and modifications that do not depart from the spirit and scope of the broad inventive concepts.

Claims

1. An interface between a battery and an electrical device, the interface comprising: Male terminal; as well as, a female terminal configured to receive the male terminal, the female terminal having a female contact of a conductive material, and the male terminal having a male contact of a conductive material; wherein, At least one of the female contact and the male contact is elastically deformable so that insertion of the male terminal into the female terminal provides a face-to-face contact area in which the male contact and the female contact engage each other, wherein the female terminal has a recess for receiving the male terminal, and the female contact has elastically deformable portions on at least two opposite sides of the recess, wherein the elastically deformable portions of the female contact are bent inwardly into the recess before the male terminal is inserted, wherein the female contact is provided by elastically deformable strips which are held in compression in the recess so that the strips are bent inwardly, the strips are elongated and extend in the insertion and extraction direction of the male terminal, characterized in that The strips extend from an integrally formed elongated cross member such that the strips are spaced apart along an edge of the cross member to form a comb structure, wherein the recess has two comb structures such that the cross members of each comb structure are spaced apart and the strips from each comb structure are interlaced.

2. The interface between a battery and an electrical device according to claim 1, wherein: The male terminal has a housing with an opening through which the male contact extends and in which the male contact is mounted for movement within the opening.

3. The interface between a battery and an electrical device according to claim 2, wherein: The opening is planar and the movement is parallel to the direction of the opening plane.

4. The interface between a battery and an electrical device according to claim 3, wherein: The male contact is fixed in a direction perpendicular to the plane of the opening.

5. The interface between a battery and an electrical device according to claim 1, wherein: These strips include copper, silver or a conductive alloy.

6. An interface between a battery and an electrical device according to any one of the preceding claims, wherein: During use, the current flowing between the battery and the device is between 40 amps and 400 amps.

7. An interface between a battery and an electrical device according to any one of the preceding claims 1 to 5, wherein: The male contact has a cross section transverse to the insertion direction, the smallest dimension of the cross section being between 3 mm and 20 mm.

8. An interface between a battery and an electrical device according to any one of the preceding claims 1 to 5, wherein: The insertion force of the male terminal into the female terminal is between 5 Newtons and 50 Newtons.

9. An interface between a battery and an electrical device according to any one of the preceding claims 1 to 5, wherein: The disassembly force for disengaging the male terminal from the female terminal is between 2 Newtons and 30 Newtons.

10. An interface between a battery and an electrical device according to any one of the preceding claims 1 to 5, wherein: The battery includes the female terminal.

11. An interface between a battery and an electrical device according to any one of the preceding claims 1 to 5, wherein: Further included are spade-type or pin-type male contacts and matching female contacts for transmitting electrical data signals.

12. The interface between a battery and an electrical device according to claim 11, wherein: The data signal indicates one or more of the following: Battery level, Battery temperature, and Remaining operation time.

13. An electrical device having an interface between a battery and the electrical device according to any one of the preceding claims.

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