Patent Application
20250158198
The present invention relates to handheld battery-operated power tools, rechargeable battery packs, combinations of and systems comprising such power tools and battery packs, methods of controlling such power tools and battery packs, and computer programs implementing such methods.
Handheld power tools, such as chainsaws, have been known for the last 100 years or so. Due to considerations of weight vs power and operation time, most chainsaws are still powered by internal combustion engines of two-stroke type, but battery powered chainsaws are becoming increasingly popular. However, obtaining high output power without compromising other aspects of the chainsaw, such as cost, weight, battery life before recharging, and usability of the battery with other types of products, still remains a challenge.
It is an object of the present invention to solve, or at least mitigate, parts or all of the above mentioned problems. To this end, there is provided a handheld battery-operated power tool comprising a work implement; an electric motor configured to operate the work implement; and a connector assembly configured to be releasably coupled to a mating connector counterpart of a removable, rechargeable battery pack, for transfer of electric power to the electric motor, wherein the connector assembly comprises a connector temperature sensing arrangement configured to sense a temperature of the connector assembly. The connector temperature sensing arrangement makes it possible to, at least temporarily, draw higher current from the battery pack than would otherwise be possible, since the actual conditions of the connector assembly may be monitored. For example, use of Li-ion cells in the battery pack may enable a rather wide operating voltage of, for example, between about 25V and about 42V for a power tool system specified to operate at 36 V, depending on the state of charge of the battery pack. Such a wide voltage range may require increased current during discharge of the battery pack, as the voltage reduces, in order to maintain a certain output power of the power tool. This generates more heat at the connector assembly. Monitoring the temperature of the connector assembly enables increasing the average power of the power tool during the discharge cycle of the battery pack. The connector temperature sensing arrangement may comprise one or more temperature sensors, which may be configured as e.g. thermistor(s) of e.g. negative temperature coefficient type. According to embodiments, the power tool may be configured to draw a maximum power of more than 1.8 KW from the battery pack. For example, the power tool may be an outdoor power tool, for example a leaf blower or a vegetation cutter such as a chainsaw or a clearing saw, or a construction tool such as a power cutter/cut-off machine for cutting e.g. masonry, metal and concrete. The power tool may comprise a battery compartment configured to receive and hold the battery pack.
According to a second aspect, at least parts of the above mentioned problems are solved, or at least mitigated, by a rechargeable battery pack configured to be removably attached to a handheld battery-operated power tool, the rechargeable battery pack comprising a plurality of rechargeable battery cells; and a connector assembly configured to be releasably coupled to a mating connector counterpart of the power tool, for transfer of electric power from the plurality of battery cells to the power tool, wherein the connector assembly comprises a connector temperature sensing arrangement configured to sense a temperature of the connector assembly. The plurality of rechargeable battery cells may be electrically interconnected in groups, for example in serial and/or parallel configuration. The plurality of battery cells may be disposed within a battery housing, and the connector assembly may comprise a set of current transfer connector terminals located so as to be accessible externally of the battery pack. The rechargeable battery cells may be of e.g. Lithium-ion type. According to embodiments, the connector temperature sensing arrangement may be positioned at a distance from the rechargeable battery cells. Thereby, thermal leakage from the rechargeable battery cells to the connector temperature sensing arrangement will be reduced. Preferably, the distance between the connector temperature sensing arrangement and the nearest battery cell exceeds 30 mm. Again, the connector temperature sensing arrangement may comprise one or more temperature sensors, which may be configured as e.g. thermistor(s) of e.g. negative temperature coefficient type. The battery pack may be configured to provide a maximum power of more than 1.8 KW to the power tool.
According to embodiments of the handheld battery-operated power tool and/or battery pack, the connector assembly may comprise a first current transfer connector terminal configured to engage with a respective mating first current transfer connector terminal counterpart of the connector counterpart at a first terminal engagement interface, wherein the connector temperature sensing arrangement comprises a first terminal temperature sensor positioned less than 60 mm from the first terminal engagement interface. The first terminal temperature sensor may be positioned within said distance e.g. along the path of a first electric current transfer line, which may be at least partly defined by a first current transfer cable. According to further embodiments, the first terminal temperature sensor may be positioned less than 40 mm from the first terminal engagement interface.
According to embodiments, the connector assembly may comprise a first current transfer cable, wherein the first terminal temperature sensor is positioned less than 8 mm from a conductor of the first current transfer cable. The first current transfer cable may be coupled to a first current transfer connector terminal as defined above. According to further embodiments, the first terminal temperature sensor may be positioned in direct abutment with the first current transfer cable.
According to embodiments, the connector assembly may comprise a second current transfer connector terminal configured to engage with a respective mating second current transfer connector terminal counterpart of the connector counterpart at a second terminal engagement interface, wherein the connector temperature sensing arrangement comprises a second terminal temperature sensor positioned less than 60 mm from the second terminal engagement interface. According to further embodiments, the second terminal temperature sensor may be positioned less than 40 mm from the second terminal engagement interface. The first current transfer connector terminal may be a positive-voltage current transfer connector terminal, and the second current transfer connector terminal may be a negative-voltage current transfer connector terminal, or vice versa. Depending on e.g. manufacturing tolerances, wear, or other connection circumstances, the first and second terminal engagement interfaces may differ from each other in electrical resistance, and may therefore develop different respective amounts of heat during current transfer. Sensing the temperature of both terminal engagement interfaces enables drawing an even higher average current from the battery pack. Also the second terminal temperature sensor may be positioned within said distance e.g. along the path of a second electric current transfer line, which may be at least partly defined by a second current transfer cable. According to further embodiments, the connector assembly may comprise a second current transfer cable coupled to the second current transfer connector terminal, and the second terminal temperature sensor may be positioned less than 8 mm from a conductor of the second current transfer cable, or in direct abutment with the second current transfer cable.)
According to embodiments, the connector temperature sensing arrangement may comprise a printed circuit board and at least two temperature sensors coupled to the printed circuit board. Such an arrangement facilitates assembly during manufacture of the power tool or battery pack, as the case may be, and ascertains accurate and precise positioning of the temperature sensors.
According to embodiments, the connector assembly may comprise a cable holder provided with one or more apertures, each configured to at least partly enclose and hold respective a current transfer cable, wherein the connector temperature sensing arrangement comprises one or more temperature sensors positioned at said one or more apertures. According to embodiments, a printed circuit board of the connector temperature sensing arrangement may also be carried by said cable holder.
According to embodiments, the handheld battery-operated power tool and/or battery pack may further comprise a rigid main body frame, wherein the connector assembly comprises a rigid connector body and a resilient connector body support, wherein the connector body is attached to the main body frame via the connector body support. Thereby, the connector assembly may automatically align itself to the position of the connector counterpart during connection, regardless of any dirt in the connector or slight positional deviations within manufacturing tolerances. This enables an improved electrical connection between the connector assembly and the connector counterpart, which increases the electric power transfer capability of, and reduces the heat generated in, the electrical connector interface defined by the connector assembly and the mating connector counterpart. According to embodiments, the connector body support may be made of an elastomer, such as natural or synthetic rubber. The connector temperature sensing arrangement may be attached to the rigid main body frame via the resilient connector body support. The rigid main body frame may be defined by, as the case may be, a power tool housing or a battery housing. According to embodiments, the battery housing may be configured to be rigidly connected to the power tool housing. Needless to say, each of the rigid main body frame and the rigid connector body may consist of several respective elements which are interconnected in a rigid manner. The rigid connector body may carry a set of current transfer connector terminals. The current transfer connector terminals may be configured as cantilever finger contacts configured to resiliently flex, during connection, in a direction perpendicular to a connection direction of the connector counterpart. The current transfer connector terminals may be hermaphroditic.
According to embodiments, the connector counterpart may be configured to be coupled to the connector assembly along a connection direction, wherein the resilient connector body support is configured to enable the connector body to resiliently yield in the connection direction. According to embodiments, the resilient connector body support may be configured to enable the connector body to resiliently yield in the connection direction over a maximum flexing range of between 0.5 mm and 4 mm. The resilient connector body support may be configured to enable the connector body to resiliently yield also in a direction perpendicular to the connection direction, or in any direction along a plane perpendicular to the connection direction. The rigid main body frame may comprise a rigid connector sheath enclosing the connector body and extending along the connection direction.
According to embodiments, the resilient connector body support may be configured as a cushion pad sandwiched between the connector body and the main body frame. Thereby, an attractive degree of flexibility may be obtained in a compact space, and at a low cost and complexity. The cushion pad may be made of elastomer, for example thermoplastic elastomer.
According to embodiments, the cushion pad may have a thickness, in the connection direction, of between 2 mm and 10 mm. According to further embodiments, the cushion pad may have a thickness in the connection direction of between 3 mm and 6 mm.
According to embodiments, the cushion pad may be integrally formed with a cable holder. The cable holder may be formed of e.g. non-elastomeric plastic, for example a non-elastomeric thermoplastic. The cable holder and cushion pad may be formed as a two-component injection-moulded element. The connector temperature sensing arrangement may be carried by the cable holder.
According to embodiments, the handheld battery-operated power tool and/or battery pack may further comprise a controller configured to set, based on a sensor signal from the connector temperature sensing arrangement, an upper power limit that can be drawn from the battery pack. According to further embodiments, the controller may be configured to, in response to a determination that the connector temperature exceeds a power limitation threshold temperature, enable the power tool to be operated in a normal-power mode, and in response to a determination that the connector temperature is below a power limitation removal threshold temperature, enable the power tool to be operated in a high-power mode, which high-power mode enables operating the power tool at a higher power than in the normal-power mode. The power tool may be equipped with a user interface, for example an indicator lamp, configured to indicate whether the power tool is in the high-power mode or in the normal-power mode. The power limitation threshold temperature and the power limitation removal threshold temperature may be the same or different. The power limitation threshold temperature and the power limitation removal threshold temperature may be static, or may be dynamically set by the controller. For example, the controller may set the power limitation threshold temperature and the power limitation removal threshold temperature based on a difference between the sensor signal from the connector temperature sensing arrangement and a sensor signal from an ambient temperature sensor separate from the connector temperature sensing arrangement. According to embodiments, the power tool may be configured to draw more than 2.5 KW in the high-power mode, and less than 2.5 KW in the normal-power mode. Exemplary suitable values of the power limitation threshold temperature and the power limitation removal threshold temperature may be, e.g., between 50° C. and 100° C. Alternatively or additionally, the controller may be configured to initiate, based on the sensor signal from the connector temperature sensing arrangement, a connector overheating protection action. The a connector overheating protection action may comprise, e.g., operating a cooling fan configured to cool the connector.
According to a third aspect, at least parts of the above mentioned problems are solved, or at least mitigated, by a handheld battery-operated power tool comprising a main body frame; a work implement carried by the main body frame; an electric motor carried by the main body frame and configured to operate the work implement; and a connector assembly configured to be releasably coupled to a mating connector counterpart of a removable, rechargeable battery pack, for transfer of electric power to the electric motor, wherein the connector assembly is configured to be coupled to the connector counterpart along a connection direction, wherein the connector assembly comprises a rigid connector body and a resilient connector body support configured as a cushion pad sandwiched between the connector body and the main body frame to enable the connector body to resiliently yield in the connection direction.
According to a fourth aspect, at least parts of the above mentioned problems are solved, or at least mitigated, by a rechargeable battery pack configured to be removably attached to a handheld battery-operated power tool, the rechargeable battery pack comprising a rigid main body frame; a plurality of rechargeable battery cells held by the main body frame; and a connector assembly configured to be releasably coupled to a mating connector counterpart of the power tool, for transfer of electric power from the plurality of battery cells to the power tool, wherein the connector assembly comprises a rigid connector body and a resilient connector body support configured as a cushion pad sandwiched between the connector body and the rigid main body frame to enable the connector body to resiliently yield in the connection direction.
According to embodiments of the handheld tool and the battery pack, respectively, the cushion pad may made of elastomer. The cushion pad may have an exemplary thickness of between 2 mm and 10 mm; more preferably between 3 mm and 6 mm, and/or may be configured to enable the connector body to resiliently yield in the connection direction over an exemplary maximum flexing range of between 0.5 mm and 4 mm. The cushion pad may be integrally formed with a cable holder provided with one or more apertures, each configured to at least partly enclose and hold respective a current transfer cable. The cable holder may be non-elastomeric, and may be integrally formed with the cushion pad by e.g. two-component injection moulding. Again, according to embodiments, the rigid main body frame may be defined by, as the case may be, a power tool housing or a battery housing. The battery housing may be configured to be rigidly connected to the power tool housing. Each of the rigid main body frame and the rigid connector body may consist of several respective elements which are interconnected in a rigid manner. The rigid connector body may carry a set of current transfer connector terminals. The current transfer connector terminals may be cantilever finger contacts configured to resiliently flex, during connection, in a direction perpendicular to a connection direction of the connector counterpart. The current transfer connector terminals may be hermaphroditic. The resilient connector body support may be configured to enable the connector body to resiliently yield also in a direction perpendicular to the connection direction, or in any direction along a plane perpendicular to the connection direction. The rigid main body frame may comprise a connector sheath enclosing the connector body and extending along the connection direction.
According to a fifth aspect, at least parts of the above mentioned problems are solved, or at least mitigated, by a combination of a handheld battery-operated power tool in accordance with any of the first and third aspects, and a battery pack in accordance with any of the second and fourth aspects. In such a combination, the connector assembly of the battery pack would define the connector counterpart to be connected to the connector assembly of the power tool, and vice versa. According to an exemplary combination, the connector assembly of the power tool may comprise a connector temperature sensing arrangement as defined hereinabove, and the connector assembly of the battery pack may comprise a cushion pad as defined hereinabove, or vice versa.
According to a sixth aspect, at least parts of the above mentioned problems are solved, or at least mitigated, by a tool system comprising a first handheld battery-operated power tool; a second handheld battery-operated power tool; and a removable, rechargeable battery pack configured to be alternately coupled to the first handheld battery-operated power tool and the second handheld battery-operated power tool, wherein the second handheld battery-operated power tool has a respective upper power limit that can be drawn from the battery pack, the respective upper power limit being independent of a temperature of an electrical coupling interface between the battery pack and the second handheld battery-operated power tool; and the first handheld battery-operated power tool is the handheld battery-operated power tool according to the first aspect defined hereinabove, wherein the respective upper power limit of the first handheld battery-operated power tool may be set to a value which is higher than the respective upper power limit of the second handheld battery-operated power tool. Such a system enables interoperation between high-power tools and legacy low-power power tools and battery packs, while maximizing the power of the high-power tools.
According to a seventh aspect, at least parts of the above mentioned problems are solved, or at least mitigated, by a method of controlling a handheld battery-operated power tool to draw power from a battery pack, the method comprising: sensing a temperature of a connector in an electrical coupling interface between the handheld battery-operated power tool and the battery pack; in response to a determination that the connector temperature exceeds a power limitation threshold temperature, enabling the power tool to be operated in a normal-power mode; and, in response to a determination that the connector temperature is below a power limitation removal threshold temperature, enabling the power tool to be operated in a high-power mode, which high-power mode enables operating the power tool at a higher power than in the normal-power mode. The power limitation threshold temperature and the power limitation removal threshold temperature may be the same or different.
According to an eighth aspect, there is provided data processing equipment comprising at least one processor and memory, configured to carry out the method defined hereinabove.
According to a ninth aspect, there is provided a computer program product comprising instructions which, when the program is executed on a processor, carries out the method defined hereinabove.
According to a tenth aspect, there is provided a computer-readable storage medium (99) having stored thereon said computer program product.
It is noted that embodiments of the invention may be embodied by all possible combinations of features recited in the claims. Further, it will be appreciated that the various embodiments described for the devices are combinable with the methods, and vice versa.
The above, as well as additional objects, features and advantages of the present invention, will be better understood through the following illustrative and non-limiting detailed description of preferred embodiments of the present invention, with reference to the appended drawings, where the same reference numerals will be used for similar elements, wherein:
All the figures are schematic, not necessarily to scale, and generally only show parts which are necessary in order to elucidate the embodiments, wherein other parts may be omitted.
Now with reference to
Now returning to the connector assembly 32 of the power tool 10 (
The terminal temperature sensors 60a, 60b are connected to the controller 26 (
The cross-section of
In the section of
It will be appreciated that the second current transfer connector terminal 40b (
Similarly, it will be appreciated that alternatively or additionally, the connector assembly 132 (
Similarly, it will be appreciated that the rigid connector body 134 of the connector assembly 132 of the battery pack 20 may be resiliently connected to the housing 21 of the battery pack 20 via a resilient cushion pad, so as to enable the connector body 134 to flex in relation to the battery pack housing 21.
In step 901, the controller 26 senses, using the connector temperature sensing arrangement 58, the temperature of a connector, i.e. connector 30 (
In step 902, the controller 26 determines whether the connector temperature exceeds the power limitation threshold temperature. If so, the controller sets the power tool 10 or battery pack 20 in a mode enabling the power tool 10 to be operated in a normal-power mode, while preventing operation in the high-power mode.
In step 903, the controller 26 determines whether the connector temperature is below the power limitation removal threshold temperature. If so, the controller 26 sets the battery pack 20 or power tool 10 in a mode enabling the power tool 10 to be operated in the high-power mode, wherein the high-power mode enables operating the power tool 10 at a higher power than in the normal-power mode.
The invention has mainly been described above with reference to a few embodiments. However, as is readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the invention, as defined by the appended patent claims.
For example, the invention has been described with reference to a chainsaw of rear-handle type. However, it will be appreciated that the teachings herein are equally applicable to a chainsaw of top-handle type. The temperature sensor(s) of the connector temperature sensing arrangement need not be positioned in direct abutment with current transfer cables; it/they can be positioned at another suitable location within the connector assembly.
In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2250130-8 | Feb 2022 | SE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/SE2023/050033 | 1/12/2023 | WO |
