Patent Application
20230211519
The present invention relates to chainsaws, and more particularly to high power compact cordless chainsaws.
Chainsaws include chains which are driven about a guide bar to make cuts in work pieces. Conventional chainsaws are bulky, heavy, and either are gas or otherwise powered, or are battery powered. Conventional battery powered chainsaws are limited in instantaneous power output and sustained power output in terms of number of cuts per charge of the battery.
In one embodiment invention provides, a chainsaw configured to be powered by a battery pack. The chainsaw includes a housing, a guide bar, and a power and drive assembly. The housing includes a battery interface for receiving the battery pack. The guide bar guides a cutting chain and is removably coupled to the housing. The power and drive assembly includes a motor and a gear train. The motor is disposed within the housing and is configured to be powered by the battery pack. The gear train is driven by the motor and configured to drive the cutting chain. The housing, the guide bar, and the power and drive assembly each contribute to a total weight of the chainsaw. A power output by the power and drive assembly compared to the total weight defines a power-to-weight ratio of above 150 Watts per Pound.
In another independent embodiment, the invention provides a chainsaw configured to be powered by a battery pack. The chainsaw includes a housing, a guide bar, and a power and drive assembly. The housing includes a battery interface for receiving the battery pack and defines a receptacle. The guide bar guides the cutting chain and is removably coupled to the housing. When coupled to the housing, the guide bar is at least partially received in the receptacle. The guide bar has a length extending between a distal end of the guide bar and the receptacle. The power and drive assembly is configured to drive the cutting chain about the guide bar. A power output of the power and drive assembly compared to the length of the guide bar defines a power-to-length ratio of above 140 Watts per inch.
In another independent embodiment, the invention provides a chainsaw configured to be powered by a battery pack. The chainsaw includes a housing, a guide bar, and a power and drive assembly. The housing includes a battery interface, the housing having a length. The guide bar guides a cutting chain and is removably coupled to the housing. The power and drive assembly is configured to drive the cutting chain about the guide bar. A power output of the power and drive assembly compared to the length of the housing defines a power-to-length ratio of above 75 Watts per inch.
Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.
The automatic oiling assembly 500 further includes a pump cylinder 528 and a pump housing 532.
The automatic oiling assembly 500 further includes a pump inlet tube 556 with a first end 556a coupled to the oil tank 504 and an opposite second end 556b coupled to the pump inlet 548. The automatic oiling assembly 500 further includes a pump outlet tube 560 with a first end 560a coupled to the pump outlet 552 and a second end 560b terminating adjacent the guide bar 200 and the chain 204.
Accordingly, during operation of the portable chainsaw 10, the output shaft 320 rotates the oiler shaft 508. When the key 524 is aligned with the inlet opening 540, oil from the oil tank 504 is passed through the pump inlet tube 556 through the pump inlet 548 and the inlet opening 540 and to a location between the key 524 and the passageway 536. The output shaft 320 continues to rotate until the key 524 is aligned with the outlet opening 544. At this time, oil from between the key 524 and the passageway 536 is passed through the outlet opening 544 and the pump outlet 552 and through the pump outlet tube 560 to a position adjacent the guide bar 200 and the chain 204. Accordingly, the automatic oiling assembly 500 is driven by the gear train 308, the automatic oiling assembly 500 being configured to receive mechanical input from the gear train 308 and transmit oil from the oil tank 504 to at least one of the guide bar 200 and the chain receives oil from the oil tank 504. During operation of the automatic oiling assembly 500, the oiler shaft 508 including the key 524, in conjunction with the passageway 536 of the pump cylinder 528 function as a pump (e.g., an axial piston pump) to transmit oil from the oil tank 504 to at least one of the guide bar 200 and the chain 204. Other such pump mechanisms may be similarly driven by the output shaft 320. For example, the oiler shaft 508 may be configured to power other types of pumps, such as, and without limitation, an external gear pump, an internal gear pump, a gerotor pump, a peristaltic pump, or a lobe pump.
Returning to
The housing 100 further includes a guide bar receptacle 108 within which at least a portion of the guide bar 200 is received. In the illustrated embodiment, the guide bar receptacle 108 is positioned generally on the opposite end of the housing 100 as the battery interface 104. With continued reference to
With continued reference to
The housing 100 further includes a primary handle 112 extending between the motor 304 and the battery interface 104 along a primary handle axis A6. The primary handle axis A6 is generally perpendicular to the battery axis A4. The primary handle axis A6 traverses the motor axis A1 at an angle AN2. The angle AN2 is near perpendicular, but is slightly less than 90 degrees. For example, in the illustrated embodiment, the angle AN2 is approximately 86 degrees. Other angles AN2 are possible.
The housing 100 further includes a handle guard 116 coupled to the battery interface 104 and extending generally toward the guide bar 200. The trigger 312 is positioned between the primary handle 112 and the handle guard 116. Accordingly, during use of the portable chainsaw 10, an operator's hand holding the primary handle 112 and touching the trigger 312 may be shielded from any cuttings generated by the chain 204. The handle guard 116 extends along a guard axis A7. In the illustrated embodiment, the guard axis A7 is angled relative to the battery axis A4 an angle AN3. The angle AN3 in the illustrated embodiment is oblique. The angle AN3 in the illustrated embodiment is an obtuse angle, and is approximately 106 degrees. Other angles AN3 are possible.
The housing 100 further includes a motor receptacle 120 within which the motor 304 is received. The portable chainsaw 10 further includes a hand guard 124 coupled to the guide bar receptacle 108 and the motor receptacle 120. The hand guard 124 includes a first portion 124a and a second portion 124b. The first portion 124a extends along a first hand guard axis A8. In some embodiments, the first portion 124a may have indicia to indicate to a user not to grasp the hand guard 124. The second portion 124b extends along a second hand guard axis A9. The first hand guard axis A8 is generally parallel with the motor axis A1. The second hand guard axis A9 is generally perpendicular with the motor axis A1. The hand guard 124 may inhibit debris or other material from contacting a user.
With continued reference to
One consideration that allows the portable chainsaw 10 to be compact is the location of the control electronics 314. In the illustrated embodiment, at least one component of the control electronics 314 is mounted upon a printed circuit board 317. The printed circuit board 317 is positioned within the motor receptacle 120 at a position opposite the motor 304 when compared to the gear train 308 (the gear train 308 including the sprocket 332). The motor axis A1 passes through the printed circuit board 317. The printed circuit board 317 is angled relative to the motor axis A1 at an angle AN4. The angle AN4 in the illustrated embodiment is acute and is approximately 76 degrees. Other angles AN4 are possible.
Various components of the portable chainsaw 10 contribute to high power-output and high efficiency of the chainsaw 10, leading to high performance of the portable chainsaw 10. First, the battery pack 400 is a high-performance battery pack 400. In the illustrated embodiment, the battery pack 400 is lithium-based. Other battery packs may be nickel-based, or have differing chemistries. The battery pack 400 may be a high-output battery pack (e.g., 6.0 Ah), such as the M18™ REDLITHIUM™ HIGH OUTPUT™ XC6.0 battery pack, manufactured and sold by Milwaukee Electric Tool, Milwaukee, Wis. Such a battery pack 400 weighs approximately 2.3 pounds (1.0 kilograms). The battery pack 400 may be operable to provide at least 1000 Watts of electrical input power to the power and drive assembly 300. In some embodiments, the battery pack 400 has an operating voltage of approximately 18 volts. The battery pack 400 may have, for example, an output current of 6.0 amps. Other suitable battery packs 400 may have different operating voltages, output currents, power outputs, and/or different weights.
The battery pack 400 is also a high-capacity battery pack 400. When the battery pack 400 is used to power the portable chainsaw 10, the battery pack 400 is configured to make at least 150 cuts of 3.5-inch by 3.5-inch (8.9-centimeter by 8.9-centimeter) (e.g., a piece of dimensional lumber commonly referred to as a “four by four”) pressure-treated lumber on a single charge. For instance, the pressure-treated lumber may be pine. The battery pack 400 can make at least 160 cuts of 3.5-inch by 3.5-inch (8.9-centimeter by 8.9-centimeter) pressure-treated lumber on a single charge. In some instances, the battery pack 400 can make 179 cuts of 4-inch by 4-inch (10 centimeter by 10-centimeter) pressure-treated lumber on a single charge. Similarly, when the battery pack 400 is used to power the portable chainsaw 10, the battery pack 400 is configured to make at least 80 cuts of 5.5-inch by 5.5-inch (14-centimeter by 14-centimeter) (e.g., a piece of dimensional lumber commonly referred to as a “six by six”) pressure-treated lumber on a single charge. In fact, the battery pack 400 can make at least 89 cuts of 5.5-inch by 5.5-inch (14-centimeter by 14-centimeter) pressure-treated lumber on a single charge.
During cutting of the 3.5-inch by 3.5-inch (8.9-centimeter by 8.9-centimeter) and 5.5-inch by 5.5-inch (14-centimeter by 14-centimeter) pressure-treated lumber, a downforce of approximately 30 pounds (13.6 kilograms) was applied to the portable chainsaw 10 in a direction DF (
The control electronics 314 and the printed circuit board 317 must also be constructed of adequate quality (e.g., size, capacity) to provide adequate capacity to transmit the at least 1000 Watts of electrical input power to the motor 304. For example, wires W (
Next, the motor 304 must be a high-power motor 304. The motor 304 must operate at torque and speed configured to provide output mechanical power to drive the chain 204 around the guide bar. In some embodiments, this output mechanical power is at least 1000 Watts. The motor 304 is operable to output a maximum output power while cutting a workpiece of 3.5-inch by 3.5-inch (8.9-centimeter by 8.9-centimeter) pressure-treated lumber of at least 1100 Watts. In the illustrated embodiment, the motor 304 can reach instantaneous mechanical output power of approximately 1200 Watts. This instantaneous mechanical output power was observed while the portable chainsaw 10 cut a 3.5-inch by 3.5-inch (8.9-centimeter by 8.9-centimeter) piece of pressure-treated lumber.
The automatic oiling assembly 500 may provide adequate amounts of lubrication to at least one of the guide bar 200 and the chain 204 to inhibit excess undesired heat production during rotation of the chain 204 about the guide bar 200. Such undesired heat production may cause binding of the chain 204 upon the guide bar 200, inhibiting a cutting operation of the chainsaw 10. Oil from the automatic oiling assembly 500 may absorb at least some of the heat generated between the chain 204 and the guide bar 200. The automatic oiling assembly 500 is sized to provide an adequate volumetric flow rate of lubrication from the oil tank 504 to at least one of the guide bar 200 and the chain 204. Accordingly, large amounts of power (e.g., at least a maximum of 1200 Watts, as further described below) may be applied through the chain 204 to the workpiece W without overheating of the guide bar 200 and chain 204, which may cause binding of the chain 204 onto the guide bar 200.
The housing 100 and the fastening of each of the components of the portable chainsaw 10 thereto are capable of withstanding forces generated while applying high amounts of power to the workpiece W. For example, the fastening mechanism between the guide bar 200 and the housing 100 is rigid enough to withstand both the forces generated by the chain 204 as well as the downforce in direction DF. Similarly, the bearings 324, 328 which support the output shaft 320 within thin the housing 100 can withstand the forces placed thereon during high power-output cutting of the chainsaw 10.
Each of the materials of each of the components (e.g., the guide bar 200, the motor 304, the housing 100) of the chainsaw 10 are selected to minimize weight of the chainsaw 10 while providing adequate capacity to operate the chainsaw 10 at a high power-output. For example, the guide bar 200 may be a lightweight and high strength steel alloy, stainless-steel alloy, aluminum alloy, or the like. Accordingly, the guide bar 200 may resist corrosion, hold strong edges for engaging the chain 204, while retaining enough elasticity to bend under high stress without breaking. The motor 304 may also be a lightweight and high power-output motor such as, without limitation, a brushless direct current motor. In other words, the motor 304 may have a high power-to-weight (i.e., PWR, i.e., specific power) ratio. Another example of lightweight component selection in the chainsaw 10 is the housing 100 itself. The housing 100 may be composed of a durable and light-weight plastic material. The housing 100 may optionally be formed of injection molded plastic comprising of a base material and an additive. The base material and the additive of the housing 100 each contributing to the structural rigidity and weight of the housing 100. Total weight of the chainsaw 10 less the battery pack 400 (i.e., including the guide bar 200, the power and drive assembly 300, and the housing 100) in the illustrated embodiment is approximately 4.74 pounds (2.15 kilograms). Other embodiments may have different total weights for the chainsaw 10.
The above-described features of the chainsaw 10 provide a high power-output and light weight chainsaw 10 with a compact guide bar 200 and a compact housing 100. As previously mentioned, a maximum instantaneous mechanical output power of the chainsaw 10 while cutting 3.5-inch by 3.5-inch (8.9-centimeter by 8.9-centimeter) pressure-treated lumber is approximately 1200 Watts. Other improved higher output chainsaws are envisioned upon realizing increases in efficiency of components of the chainsaw 10.
As previously mentioned, the weight of the chainsaw 10 less (i.e., without) the battery pack 400 is approximately 4.74 pounds, and the maximum output power of the chainsaw 10 is approximately 1200 Watts. Accordingly, the chainsaw 10 is a high power-output and lightweight chainsaw having a power-to-weight ratio of output mechanical power to total weight above 150 Watts per pound (330 Watts per kilogram). More specifically, the chainsaw 10 has a power-to-weight ratio of output mechanical power to total weight above 250 Watts per pound (550 Watts per kilogram). The illustrated chainsaw 10 has a power-to-weight ratio of output mechanical power to total weight of approximately 253 Watts per pound (557 Watts per kilogram).
As previously mentioned, the guide bar length L1 of the illustrated guide bar 200 is approximately 7.5 inches (19 centimeters), and the maximum output power of the chainsaw 10 is approximately 1200 Watts. Accordingly, the chainsaw 10 is a high power-output and compact guide bar 200 chainsaw 10 having a power-to-length ratio of output mechanical power to guide bar length L1 greater than 100 Watts per inch (39 Watts per centimeter). More specifically, the chainsaw 10 has a power-to-length ratio of output mechanical power to guide bar length L1 greater than 140 Watts per inch (55 Watts per centimeter). The illustrated chainsaw 10 has power-to-length ratio of output mechanical power to guide bar length L1 approximately 160 Watts per inch (63 Watts per centimeter).
As previously mentioned, the maximum housing length L2 of the illustrated housing 100 is approximately 12 inches, and the maximum output power of the chainsaw 10 is approximately 1200 Watts. Accordingly, the chainsaw 10 is a high power-output and compact housing 100 chainsaw 10 having a power-to-length ratio of output mechanical power to maximum housing length L2 greater than 50 Watts per inch (20 Watts per centimeter). More specifically, the chainsaw 10 has a power-to-length ratio of output mechanical power to maximum housing length L2 greater than 75 Watts per inch (30 Watts per centimeter). The illustrated chainsaw 10 has power-to-length ratio of output mechanical power to maximum housing length L2 approximately 100 Watts per inch (40 Watts per centimeter).
Although the invention has been described in detail with reference to certain preferred embodiments, variations and modifications exist within the scope and spirit of one or more independent aspects of the invention as described.
Various features of the invention are set forth in the following claims.
This application claims priority to co-pending U.S. Provisional Patent Application No. 63/296,907 filed on Jan. 6, 2022, the entire content of which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 63296907 | Jan 2022 | US |
