Patent Application
20190344366
This invention relates to power tools and particularly, although not exclusively, to electrical saws with cutting element position control.
A power tool with a cutting element, such as a blade, often requires the user to change the cutting element. For example, in a jigsaw, the existing blade may wear out and become dull after a short period of time, or the user may wish to change to a different type of blade for cutting a different material or produce a different finish.
Depending on the different types of power tool, some blades are held in place by a screw that may be loosened when the users need to change the blade. Alternatively, some blades may be released from the blade clamp when a lever is disengaged, or through any other tool-less mechanisms.
It is desirable to position the blade at the highest position, away from the object being cut, such that the user can change the blade easier and prevent damaging the object. However, there is usually a delay between a user stopping the blade, e.g. by pressing the “off” power button, and the blade actually being stopped by the motor, hence the blade may end up being stopped in the middle of the reciprocating range.
In the light of the foregoing background, it is an object to address the above needs, to overcome or substantially ameliorate the above disadvantages or, more generally, to provide a power tool with position control for changing the cutting element.
The above object is met by the combination of features of the main claims; the dependent claims disclose further advantageous embodiments of the invention.
One skilled in the art will derive from the following description other objects of the invention. Therefore, the foregoing statements of object are not exhaustive and serve merely to illustrate some of the many objects of the present invention.
Accordingly, the present invention, in one aspect is a power tool comprising a cutting element, a sensor arranged to detect a position of the cutting element, and a controller operably connected with the sensor and the drive mechanism, for controlling a stopping position of the cutting element based on the detection by the sensor.
Preferably, the power tool further comprises an input module for receiving an input from a user to activate the detection by the sensor, and that the sensor is arranged to detect a relative position between the sensor and a sensed object of the cutting element.
According to a variation of the preferred embodiments, the sensed object is a magnet and it is being positioned on one end of the cutting element; whereas the sensor is a hall sensor and it is being positioned proximate to the sensed object of the cutting element at the stopping position.
More preferably, the sensor detects the position of the cutting element when the sensed object of the cutting element moves within a measuring range of the sensor.
Additionally, the drive mechanism of the power tool includes a motor, and wherein the motor effectuates a reciprocating motion of the cutting element.
Preferably, upon the sensor detects the cutting element at the stopping position, the drive mechanism is arranged to brake the motor immediately.
Alternatively, upon the sensor detects the cutting element at the stopping position, the drive mechanism is arranged to brake the motor after a predetermined amount of rotation.
In another aspect, the present invention is a method for controlling a stopping position of a cutting element in a power tool, comprising the steps of detecting a position of the cutting element by a sensor, transmitting the detected position to a controller and altering an operation of a drive mechanism for positioning the cutting element at the stopping position, wherein the drive mechanism is arranged to be controlled by the controller.
Preferably, the method further comprises the step of receiving an input from a user to activate the detection by the sensor; and wherein the sensor is arranged to detect a relative position between the sensor and a sensed object of the cutting element
According to a variation of the preferred embodiments, the sensed object is a magnet and it is being positioned on one end of the cutting element; whereas the sensor is a hall sensor and it is being positioned proximate to the sensed object of the cutting element at the stopping position.
More preferably, the method further comprises the step of detecting the position of the cutting element by the sensor when the sensed object of the cutting element moves within a measuring range of the sensor,
Additionally, the drive mechanism of the power tool includes a motor, and wherein the motor effectuates a reciprocating motion of the cutting element.
Preferably, the method further includes the step of braking the motor immediately upon detection of the cutting element at the stopping position.
Alternatively, the method further includes the step of braking the motor after a predetermined amount of rotation upon detection of the cutting element at the stopping position.
In one specific implementation, the power tool is a jigsaw.
Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings.
When changing the cutting element, it is desirable to stop the cutting element at a higher position away from the object being cut, ideally the highest position. By utilizing a sensor to detect a sensed object in the cutting element in the present invention, this method of control in a power tool is automatic and reliable, allowing the user to change the cutting element easily and efficiently.
The foregoing and further features of the present invention will now be described, by way of example, with reference to the accompanying drawings in which:
Referring now to
In one embodiment, a tool-less clamp mechanism 26 is arranged to receive the cutting element 12. In other embodiments, tooled mechanisms such as screws or other tool-less mechanisms may be used to receive the cutting element 12. In this example, the cutting element 12 includes a saw blade.
The sensor 28 is arranged to detect a relative position between the sensor 28 and a sensed object 34 of the cutting element 12, preferably within a measuring range of the sensor 28. In one example embodiment, the clamp mechanism 26 couples a saw bar 32 on one end, and receives a saw blade 12 on the other end. The sensed object 34 is a magnet being positioned on one end of the saw bar 32, preferably the highest end of the saw bar 32, whereas the sensor 28 is a hall sensor being positioned proximately to the magnet 34 of the saw bar 32 at the stopping position. The magnet 34 appears to be circular in this embodiment. Preferably, the stopping position is configured to be at the highest point in the reciprocating motion of the sensed object 34 of the saw bar 32. This provides the user an easier and more convenient, efficient manner to change the saw blade 12 when the saw bar 32 is stopped at the highest point.
While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only exemplary embodiments have been shown and described and do not limit the scope of the invention in any manner. It can be appreciated that any of the features described herein may be used with any embodiment. The illustrative embodiments are not exclusive of each other or of other embodiments not recited herein. Accordingly, the invention also provides embodiments that comprise combinations of one or more of the illustrative embodiments described above. Modifications and variations of the invention as herein set forth can be made without departing from the spirit and scope thereof, and, therefore, only such limitations should be imposed as are indicated by the appended claims.
Although not shown in the figures, but in other embodiments, the power tool 10 may be another type of tools or devices that comprises a cutting element 12, preferably moving in a reciprocating motion, such as a hammer drill, a sabre saw or the like. Similarly, the cutting element 12 may be other output tools, the sensor 28 may be placed at or below the drive mechanism 30, on the left-hand side, in front of, or behind the cutting element 12, and the sensed object may be a magnet 34 of rectangular, square shape, or the like. The sensor 28 may be an infrared sensor radiating infrared light beam, wherein the sensed object 34 is an object reflecting the infrared light beam, such that the infrared sensor detects the infrared light beam radiated from the sensed object 34 when the sensed object 34 is within the measuring range of the sensor 28.
According to embodiments illustrated above, the sensed object 34 moves in a reciprocating motion within the measuring range of the sensor 28, and the sensor 28 only detects the motion of the sensed object 34 once activated by a user. In other embodiments, the sensor 28 may be configured to be positioned above the highest point of the reciprocating motion of the sensed object 34. During operation, the sensed object 34 of the saw bar 32 moves in a reciprocating motion below the measuring range of the sensor 28. When the saw blade 12 needs to be changed, upon request by the user through the input module, the sensed object 34 of the saw bar 32 then moves within the measuring range of the sensor 28, thereby allowing the saw bar 32 to be positioned above the highest point of the normal reciprocating motion.
Terms such as “forward”, “rearward”, “in front of”, “behind”, “highest”, “lowest” and similar terms as used herein are for the purpose of describing the invention in its normal in-use orientation and are not intended to limit the invention to any particular orientation.
Any reference to prior art contained herein is not to be taken as an admission that the information is common general knowledge, unless otherwise indicated.
| Number | Date | Country | Kind |
|---|---|---|---|
| 201810443286.9 | May 2018 | CN | national |
