CN116551747A - Electric tool and control system thereof - Google Patents

Abstract

The present application relates to power tools, and in particular to power shears, and control systems therefor. The power tool includes a motor (12), an actuator (14), a transmission (16), and a trigger (30), a moving or actuator in the transmission serving as a feedback component for the power tool, the control system comprising: an association member (22) associated with the trigger and the feedback member and having a feedback parameter that varies in response to actuation of the trigger and movement of the feedback member, the association member being configured to return the feedback parameter to an initial value corresponding to a first position of the trigger before actuation when the execution member reaches a position corresponding to a second position to which the trigger is actuated; a sensor (24) for sensing a feedback parameter of the associated component and generating a control signal based on the real-time instance; and a motor controller (26) that selectively switches the motor to an active or inactive state in response to receiving a control signal from the sensor.

Description

Electric tool and control system thereof

Technical Field

The present application relates to a control system for a power tool and a power tool including the control system.

Background

The electric shears belong to a portable electric tool, in particular to an electric cutting device, can be used for pruning in agriculture, tree cultivation, grape cultivation or gardening, and can also be used for pruning and/or cutting workpieces of hard materials such as metal.

When the power to the electric shears is turned on, and the operator actuates the trigger, the movable blade of the electric shears moves from the open position toward the closed position, and a cutting operation is performed. In some applications, it may be desirable for the cutting operation to be performed in multiple stages or steps, with the movable blade being able to controllably reside in one or more positions.

In order to be able to stop the movement of the movable blade in time and accurately when the operator's actuation of the trigger is stopped, some electric shears employ hall sensors to control the movement of the movable blade based on the position of the trigger. However, other magnetic elements are also typically arranged in the power tool near the control unit including the hall element, which magnetic elements may interfere with the hall sensor, accidentally activating the motor to move the movable blade. Without the knowledge of the operator, the moving movable blade may make undesired cuts to the workpiece or cause injury to the operator.

Still other power tools use other types of sensors, such as mechanical or optical sensors, to control the movement of the movable blade, but frequently suffer from the phenomenon that the position of the trigger does not correspond to the position of the movable blade, such as the trigger being actuated to deviate from an initial position and stopping in an actuated position, the movable blade not rotating. Further, during use of the electric shears, it is also desirable that the movable blade be able to stay in the corresponding desired position in a timely and accurate manner in response to cessation of actuation of the trigger.

Disclosure of Invention

It is an object of the present application to improve a control system for a power tool and to solve at least one of the above mentioned technical problems.

To this end, in a first aspect of the present application, there is provided a control system for a power tool,

the power tool includes a motor, an actuating member that outputs a desired motion upon actuation of the motor, a transmission that transmits the motion output by the motor to the actuating member, and a trigger adapted to be actuated by an operator, wherein one of the moving member or the actuating member in the transmission is used as a feedback member of the power tool, the control system comprising:

an association component associated with both the trigger and the feedback component and having a feedback parameter having an initial value corresponding to a first position of the trigger prior to actuation and a real-time value that varies in response to both actuation of the trigger and movement of the feedback component, the association component being configured to return the feedback parameter to the initial value when the execution component reaches a position corresponding to a second position to which the trigger is actuated;

a sensor configured to sense a real-time value of a feedback parameter of the associated component, and to generate a first control signal when the real-time value deviates from the initial value and to generate a second control signal when the real-time value returns to the initial value; and

a motor controller in communication with the sensor and configured to switch the motor to an active state in response to receiving the first control signal from the sensor and to switch the motor to an inactive state in response to receiving the second control signal from the sensor.

In one embodiment, each of the first and second positions is an initial position corresponding to the power tool being in a rest state or a trigger position different from the initial position.

In one embodiment, the motor controller causes the motor to output a rotation in a first rotational direction based on receiving the first control signal when the trigger is moved from the first position to a second position in a direction away from the initial position; or when the trigger is moved from the first position to a second position in a direction toward the initial position, the motor controller causes the motor to output a rotation in a second rotational direction opposite to the first rotational direction based on receiving the first control signal.

In one embodiment, the associated component is an elastically deformable element, the feedback parameter is an elastic deformation force, and the sensor is a force sensor.

In one embodiment, the elastically deformable element is a spring.

In one embodiment, the association component is associated with the trigger directly or indirectly, and with the feedback component directly or indirectly via an intermediate component.

In one embodiment, the sensor is arranged on the associated component, on an end of the trigger abutting the associated component, or on an end of the intermediate component or the feedback component abutting the associated component.

In a second aspect of the present application, there is provided a power tool including: the control system; the motor, the actuator, the transmission, and the trigger, wherein a moving part of the transmission or the actuator is used as a feedback part of the control system.

In one embodiment, the implement is a tool configured to perform a desired operation on a workpiece.

In one embodiment, the actuator rotates and/or translates when the trigger is triggered.

In a third aspect of the present application, there is provided an electric shears comprising: a motor that holds a movable blade that pivots relative to the fixed blade between an open position and a closed position; a transmission device for transmitting the driving force output by the motor to the movable blade, a trigger suitable for being triggered by an operator, and the control system, wherein the movable blade is used as an execution part of the control system, and one of the moving parts in the transmission device or the movable blade forms a feedback part of the control system.

In one embodiment, the feedback component has a cam-shaped outer surface associated with the association component, the cam-shaped outer surface being designed such that: and returning the feedback parameter of the associated component to an initial value when the movable blade reaches a position corresponding to the second position of the trigger.

In one embodiment, the transmission includes: an output gear directly driving the movable blade to pivot, and a bevel gear driving the output gear to rotate; and a shaft rotating in synchronization with the output gear and the bevel gear; the cam-shaped outer surface is provided by a cam integrally formed with or attached to one of the output gear, the bevel gear and the shaft.

In one embodiment, the electric shears further comprises a slidably disposed pin having one end abutting the cam-shaped outer surface and the other end abutting the associated component.

In one embodiment, the associated component is a spring with two ends abutting the pin and the trigger, respectively, and the sensor is a force sensor.

In one embodiment, the force sensor is disposed at an end of the pin that abuts the spring.

In the control system of the electric tool provided by the application, in one aspect, the association component is associated with the trigger and the feedback parameter is changed from an initial value to a target value in response to actuation of the trigger, and the sensor generates a first control signal for enabling the motor controller to activate the motor in response to the change; in another aspect, the associating means is associated with a feedback means in the drive chain and returns the feedback parameter from the target value to the initial value in response to movement of the feedback means associated with the position of the executing means, the sensor generating a second control signal in response to this return causing the motor controller to switch the motor to the inactive state. To this end, by providing the moving part in the drive chain as a feedback part and being associated with the associated part, the sensor sensing the feedback parameter of the associated part can sense and generate a signal to the motor controller once the actuation part reaches the desired position corresponding to the second position of the trigger when the trigger is actuated from the first position and stays to the second position. The motor controller then stops operation of the motor, stopping movement of the implement. This enables the position of the actuating element to correspond to the position preparation of the trigger, i.e. the operator can better control the position of the actuating element by means of the trigger. In the case where the associated component is a spring and the sensor is a force sensor that senses the elastic deformation force of the spring, the power tool of the present application also avoids unsafe situations that occur when using hall sensors in the prior art.

Drawings

The present application will be more fully understood from the following detailed description of the specific embodiments taken in conjunction with the accompanying drawings, in which like reference numerals refer to like elements in the drawings.

Fig. 1 is an exemplary block diagram of a control system of a power tool according to the present application.

Fig. 2 is a schematic view of an electric shears as one example of a power tool incorporating the control system of fig. 1, wherein the movable blade of the electric shears is in an open position.

Fig. 3 is a partial cross-sectional view of fig. 2.

Fig. 4 is a schematic view of the electric shears of fig. 2 with the movable blade of the electric shears in a closed position.

Fig. 5 is a partial cross-sectional view of fig. 4.

Detailed Description

The present application relates to a feedback control system for a power tool, in particular a power cutting tool, and a power tool, in particular a power shears, comprising such a control system.

As shown in the schematic block diagram of fig. 1, the electric power tool provided with the present control system includes a motor 12 as a power source, an execution member 14 configured to execute or output a desired motion under the drive of the motor 12, and a transmission 16 transmitting the drive force or motion provided by the motor 12 to the execution member 14, the motor 12, the transmission 16, and the execution member 14 constituting a drive chain 10. The implement 14 may have different configurations for different power tools, for example, may be different types of cutters; the movement performed by the actuator 14 under the drive of the motor 12 may also be different, for example translational and/or rotational. The transmission 16 may also be any known structure in the art, such as a common gear structure, including a series of moving components that convert rotation output at the output shaft of the motor 12 into translation and/or rotation of the implement 14, including, but not limited to, gears of an appropriate type.

The power tool also includes a trigger 30 configured to be triggered or moved or actuated by an operator's hand or foot. The trigger 30 has an initial position when not actuated by the operator, and a trigger position that the trigger 30 can reach when actuated by the operator. The initial position of the trigger 30 may correspond to the motor 12 not being powered on (rest position) or the motor having been powered on but the trigger 30 has not been actuated (the power tool may be provided with a main switch for powering the motor 12). The trigger 30 may have at least one, e.g., one or more trigger positions. For example, in some embodiments, trigger 30 may have only one trigger position. In some embodiments, the trigger 30 may have a plurality of trigger positions, including, for example, a maximum travel position corresponding to the motor 12 outputting a predefined maximum power and one or more intermediate positions between the initial position and the maximum travel position, such as in the intermediate position of the trigger 30, the motor operating with intermediate power proportional or not proportional to the degree of actuation of the trigger 30. In embodiments where the trigger 30 has multiple trigger positions, the multiple trigger positions may be a plurality of preset trigger positions provided in discrete form, alternatively, the trigger 30 may have a plurality of trigger positions that vary steplessly. For different power tools, the trigger 30 may be any configuration of trigger or actuating element such as, but not limited to, a push button, a knob, a toggle, a lever, a trigger (see fig. 2-5), or the like.

In this application, actuation of the trigger 30 may move the trigger 30 from a first (pre-actuation) position to a second (post-actuation) position, wherein either the first or second position of the trigger 30 may be any position of the trigger 30, such as the initial position described previously or any trigger position of the trigger 30. Accordingly, the actuation member 14 may move (translate and/or rotate) from a position corresponding to a first position of the trigger 30 to a position corresponding to a second position of the trigger 30 in response to actuation of the trigger 30.

As shown in fig. 1, the power tool further includes a control system 20 configured in accordance with the principles of the present application, including an associated component 22, a sensor 24, and a motor controller 26, the motor controller 26 being communicatively coupled to the sensor 24 and configured to control the motor 12 (e.g., switching between an active state and an inactive state of the motor 12). The association component 22 has a feedback parameter with a preset initial value corresponding to the first position of the trigger 30. The feedback parameter of the association unit 22 has the same initial value regardless of whether the first position of the trigger 30 is the initial position or any trigger position.

The association component 22 of the control system 20 is associated with the trigger 30 and is configured such that the feedback parameter of the association component 22 changes from an initial value to a (preset) target value corresponding to the second position when the trigger 30 is actuated from the first position to the second position. The association member 22 is also associated with a feedback member in the drive chain 10 of the power tool, which may be a moving member in the drive chain from the output shaft of the motor to the implement, such as any one of the output shaft of the motor 12, the implement 14, and the transmission 16 coupled between the output shaft of the motor 12 and the implement 14. Alternatively, the feedback component may be an additional component associated with the motion of the execution component 14 and thus capable of reflecting the real-time position of the execution component 14. The feedback component is designed and constructed in association with the association component 22 and the execution component 14 such that the feedback parameter of the association component 22 is returned from the target value to the initial value when the execution component 14 reaches a predefined position corresponding to the second position of the trigger 30. That is, regardless of whether trigger 30 is actuated to any (second) position, when execution unit 14 reaches a predefined position corresponding to the (second) position of trigger 30, the feedback parameter of association unit 22 returns to the initial value.

The sensor 24 of the control system 20 is configured to sense a real-time value of the feedback parameter of the associated component 22 and to generate a first control signal when the real-time value deviates from an initial value and to generate a second control signal when the real-time value returns to the initial value. The motor controller 26 receives the first or second control signals from the sensor 24 and activates the motor 12 (or switches it to an activated state) to begin movement of the implement 14 in response to receiving the first control signal or turns the motor 12 off (or switches it to an deactivated state) to stop movement of the implement 14 in response to receiving the second control signal.

In this way, during operation of the power tool, the initial trigger 30 is in an initial position not actuated by the operator, the feedback parameter of the associated component 22 has an initial value, and the motor 12 is in an inactive state. When the trigger 30 is actuated by the operator from an initial position (i.e., a first position) to a certain trigger position (a second position, such as the aforementioned maximum travel position or intermediate position), the feedback parameter of the associated component 22 changes from an initial value to a target value corresponding to the trigger position. The sensor 24 senses a change in the feedback parameter or a deviation from the real-time value to generate a first control signal. The motor controller 26 receives the first control signal from the sensor 24 to place the motor 12 in an active state. The rotational movement output by the motor 12 is transmitted via the transmission 16 to the actuator 14, the actuator 14 beginning to perform the desired movement.

When the execution unit 14 reaches a position corresponding to the second position of the trigger 30, the feedback unit acts on the associated association unit 22 to return its feedback parameters to the initial values. The sensor 24 senses that the feedback parameter of the associated component 22 returns to an initial value to generate a second control signal. The motor controller 26 receives the second control signal and switches the motor 12 from the active state to the inactive state, stops the motor 12, and the actuator 14 stays in a position corresponding to the second position of the trigger 30. In this way, the execution component 14 can quickly and accurately stop at a predefined position corresponding to the post-actuation position of the trigger, and the feedback parameters of the associated component 22 are reset to the initial values.

If the aforementioned trigger 30 is resting in a certain intermediate position and the operator wishes to continue the movement of the execution means 14 and to rest in the next predefined position, the operator can actuate the trigger 30 again to the new second position with the current position (non-initial position) of the trigger 30 as the first position. Likewise, the feedback parameter of the associated component 22 changes and the sensor 24 generates a first control signal indicative of the change, the motor controller 26 again activates the motor 12. When the execution part 14 reaches a predefined position corresponding to the new second position, the feedback part returns the feedback parameter of the association part 22 to the initial value again due to the movement associated with the execution part 14, the sensor 24 generates a second control signal again and the motor controller 26 stops the operation of the motor 12 based on this signal.

As described above, in the control system of the present application, the associating means 22 is associated with the feedback means capable of reflecting the current position of the executing means 14, and when the executing means 14 reaches the position corresponding to the second position after the trigger 30 is actuated, the feedback means acts on the associating means 22 to make the change in the feedback parameter thereof equal in magnitude and opposite in direction to the change in the feedback parameter thereof by the trigger 30 acting on the associating means 22, ensuring that the executing means 14 is accurately stopped at the predefined position corresponding to the second position regardless of the trigger 30 being actuated to and staying at any second position. This allows the position that can be actually reached by the actuating member 14 of the power tool to be controlled and accurate.

The association member 22 may have any viable structure as long as it has a feedback parameter that changes precisely in response to the action of the feedback member and the trigger in the drive train, in accordance with the principles of the present control system. As an example, in the electric shears 100 to be described below, the associated component 22 is an elastic element, such as a spring, the corresponding feedback parameter is the amount of elastic deformation or the corresponding elastic deformation force, and the corresponding sensor 24 is a force sensor. Those skilled in the art will appreciate that the associated member 22 is not limited to a resilient element in which the feedback parameter in the examples below is a resilient deformation force, nor is the resilient element limited to a spring. Furthermore, depending on the actual application or actual construction, the association component 22 may be directly or indirectly associated to the trigger 30 or a feedback component in the drive chain via one or more intermediate members.

The control system of the present application may be adapted to devices with a motor and a trigger adapted for operator operation or actuation, in particular a portable power tool, such as a power cutter, where the trigger is adapted to be actuated by a user's hand or foot, although the application of the control system is not limited thereto. Examples of the electric cutting machine may include, for example, a pruning machine, a metal plate shearing machine, a fence shearing machine, a pruning machine, and a mower.

The electric power tool equipped with the above-described control system will be described in detail below with reference to fig. 2 to 5 taking the electric scissors 100 as an example. Fig. 2 and 3 illustrate the electric shears in an open position and the electric shears of fig. 4 and 5 in a closed position.

In particular, referring to fig. 2-5, the electric shears 100 includes a body 110 as a grip portion having a housing 112 and a motor (not shown) and a transmission 120 (only a portion of the transmission 120 is shown in fig. 2-5) housed within the housing 112. The fixed blade 116 extends from the main body 110, and the movable blade 118 is rotatable relative to the fixed blade 116 about the support shaft 115. The electric shears 100 includes a main switch (not shown) for powering on the motor and a trigger 130 for controlling the motor. The trigger 130 is rotatably supported by a support shaft 132, and includes an outer end 131 for operation by an operator's hand and an inner end 133 opposite the outer end 131 with respect to the support shaft 132. Upon power-up with the main switch, the operator actuates the trigger 130 and the output shaft of the motor outputs a rotational motion that is transmitted to the movable blade 118 via the transmission 120, such that the movable blade 118 pivots relative to the stationary blade 116 between the open position of fig. 2 and 3 and the closed position of fig. 4 and 5.

The fixed blade 116 and the movable blade 118 include a fixed blade 117 and a movable blade 119, respectively, facing each other, the fixed blade 117 of the fixed blade 116 and the movable blade 119 of the movable blade 118 being separated in the open position of fig. 2 and 3, and the fixed blade 117 of the fixed blade 116 and the movable blade 119 of the movable blade 118 being overlapped in a crossing manner in the closed position of fig. 4 and 5. The movable blade 119 performs a shearing operation when it contacts an article (e.g., a resin, metal, or nonmetal workpiece) placed between the fixed blade 141 and the movable blade 143 during rotation toward the fixed blade 117.

In the illustrated embodiment, a small or driving gear (not shown) may be integrally formed on or fixedly mounted to an output shaft of the motor, and the transmission 120 includes a driven bevel gear 122 driven by the small gear, the number of teeth of the driven bevel gear 122 being greater than that of the small gear to achieve a deceleration function. The driven bevel gear 122 is supported by a shaft 124 (fig. 3 and 5) and is secured to the shaft 124 by suitable means (e.g., keyed, screwed, etc.) so as to enable rotation of the shaft 124. Fixedly mounted on the shaft 124 is a cylindrical output gear 126, the output gear 126 being configured to engage and drive teeth 138 formed on the movable blade 118. The teeth 138 of the movable blade 118 are formed on a scallop or end 136, with the scallop 136 and the movable edge 119 being located on opposite sides of the support shaft 115, respectively.

The shaft 124 may include a shaft section 140 disposed between the driven bevel gear 122 and the output gear 126, the shaft section 140 having a cam-shaped outer surface 142 in a cross-section perpendicular to the direction of extension of the shaft 124. A pin 150 (fig. 3 and 5) is slidably supported by the housing of the electric shears 100 and includes a first end abutting the camming surface 142 of the shaft 124 and an opposite second end. A spring 160 (fig. 5) is disposed between the second end of the pin 150 and the inner end 133 of the trigger 130 and is in an initial state of being pre-compressed when the trigger 130 is not actuated. Therefore, the elastic deformation force of the spring 160 has an initial value when the trigger 130 is in the initial position (i.e., the open position of the movable blade 118 in fig. 2 and 3). The spring 160 acts as an associated component and the elastic deformation force acts as a feedback parameter for the feedback component.

A sensor (not shown) is provided at the second end of the pin 150 abutting the spring 160 to sense a change in the elastic deformation force of the spring 160. The sensor is configured to generate a corresponding first or second control signal when the elastic deformation force of the spring 160 deviates from an initial value or returns to an initial value. The sensor communicates (e.g., via wires to a circuit board containing motor control circuitry) with a motor controller (not shown) of the control system and transmits the generated control signal to the motor controller, which switches the motor from the inactive state to the active state or from the inactive state to the active state based on the control signal received from the sensor.

Specifically, when the trigger 130 is in the unactuated initial position, an operator actuates the trigger 130 with a finger, i.e., dials the outer end 131 of the trigger 130 toward the body 110, causing the trigger 130 to deviate from the initial position of fig. 2, e.g., to the maximum travel position of fig. 4. During this process, the spring 160 is extended and the elastic deformation force is increased to a maximum value corresponding to the maximum stroke position of the trigger 130. The sensor senses a change in the elastic deformation force of the spring 160 from an initial value to a maximum value to generate a first control signal, and provides the control signal to the motor controller. The motor controller receives the control signal from the sensor to switch the motor from the inactive state to the active state. The motor is activated to drive the movable blade 118 to pivot from the open position toward the closed position as described above.

In this process, when the shaft 124 is rotated by the driven bevel gear 122, the cam-shaped outer surface 142, which rotates in synchronization, drives the pin 150 to translate in a direction to shorten the spring 160, so that the elastic deformation force of the spring 160 becomes small, tending to return to the original value. The cam-shaped outer surface 142 is specifically designed such that the pin 150 just returns the elastic deformation force of the spring 160 to the initial value when the movable blade 118 reaches the position corresponding to the maximum stroke position of the trigger 130 (the position of fig. 4 and 5). The sensor then generates a second control signal that instructs the motor controller to switch the motor to the inactive state. The motor is deactivated accordingly and the movable blade 118 is stopped in a corresponding position in time.

It is contemplated that trigger 130 may be actuated to any intermediate position between the initial position and the maximum travel position of fig. 4 and 5, and that cam-shaped outer surface 142 is accordingly designed in association with trigger 130 and movable blade 118 such that, regardless of the position at which trigger 130 is to be positioned, the elastic deformation force of spring 160 returns to an initial value when the position of movable blade 118 corresponds to the position of trigger 130, thereby stopping movable blade 118 at that position in a timely and accurate manner.

When the operator releases the trigger 130, the spring 160 shortens in response to rotation of (the inner end 133 of) the trigger 130, and the control signal generated by the sensor in response to a reverse change in the elastic deformation force of the spring 160 causes the motor controller to control the motor output to rotate in a reverse direction, the movable blade 118 will rotate toward the open position of fig. 2 and 3 and will be stopped accurately at a position corresponding to the position (e.g., initial position) to which the trigger 130 is released.

That is, for the example of the electric shears 100, when the trigger 130 is actuated from a first position (which may be an initial direction or an intermediate position) to a second position (which may be another intermediate position or a maximum travel position) in a direction away from the initial position, the trigger 130 causes the feedback parameter (elastic deformation force) of the associated component (spring 160) to deviate from the initial value in an increasing direction and the feedback component (shaft section 140 of shaft 124) causes the feedback parameter of the associated component to vary in an opposite decreasing direction, the control signal generated by the sensor causes the motor controller to control the motor to output rotation in the first rotational direction. When the trigger 130 is actuated from a first position (which may be a neutral position or a maximum travel position) to a second position (which may be an initial direction or a neutral position) in a (return) direction towards the initial position, the trigger 130 causes the feedback parameter of the associated component to deviate from the initial value in a decreasing direction and the feedback component causes the feedback parameter of the associated component to vary in an opposite increasing direction, a control signal generated by the sensor causes the motor controller to control the motor to output a rotation in a second rotational direction opposite to the first rotational direction.

In this embodiment, the motor of the electric shears 100, the transmission 120 and the movable blade 118 constitute a drive chain of the electric shears 100, the shaft 124 of the transmission 120 being a feedback member associated with the spring 160 as an associated member via the intermediate member pin 150.

In the illustrated embodiment, the shaft 124 is formed integrally with the output gear 126, or the shaft 124 extends from the output gear 126, and the driven bevel gear 122 is secured to the shaft 124 such that the drive shaft 124 (shaft segment 140 with cam-shaped outer surface 142) and the output gear 126 rotate in synchronization. Those skilled in the art can contemplate any structure that enables the driven bevel gear 122 to drive the output gear 126 coaxially and synchronously, such as the output gear 126 and the driven bevel gear 122 each being fixed to the same separately formed shaft, or the output gear 126 and the driven bevel gear 122 being fastened together and nested on a stationary shaft, or the driven bevel gear 122 and the shaft 124 being integrally formed.

In the illustrated embodiment, the cam-shaped outer surface 142 is provided by a section of the shaft 124 (shaft section 140), the shaft 124 of the transmission 120 serving as a feedback component of the electric shears 100. Alternatively, the cam-shaped outer surface 142 may be provided by a separate cam-shaped member, for example, which is formed separately from the shaft 124, the driven bevel gear 122, and the output gear 126 and fixed to either one so as to achieve synchronous rotation. Alternatively, the cam-shaped outer surface 142 may be provided by a cam integrally protruding from either of the output gear 126 and the driven bevel gear 122. It is also contemplated that the camming surface 142 may be provided by a camming portion integrally projecting from the scallop 136 of the movable blade 118. In this case, the feedback component of the electric shears 100 is provided by the movable blade 118 itself, or alternatively by a separate cam-shaped member attached to the movable blade 118.

In the illustrated example of the electric shears 100, the spring 160 serves as an associated component, the elastic deformation force of the spring 160 serves as a feedback parameter, and the force sensor serves as a sensor for sensing a change in the feedback parameter. To this end, the spring 160, force sensor and motor controller constitute the control system of the electric shears 100.

In embodiments of electric shears, spring 160 as an associated component directly abuts trigger 130 or is associated with trigger 130, it is contemplated that an associated component of the control system may also be indirectly associated with trigger 130 of electric shears 100. In embodiments of the electric shears, the spring 160 as an associated component is indirectly associated to the feedback component-shaft 124 of the electric shears 100 via the pin 150, as will be appreciated by those skilled in the art, the associated component of the control system may also be directly associated to (e.g., abut) the feedback component of the electric shears 100. The pin 150 is not necessary or may be replaced by any other possible form of construction, as long as it is ensured that the feedback member in the drive chain can act on the associated member to change its feedback parameter.

Although certain specific embodiments have been described above for illustrative purposes, the teachings of this patent document have general applicability and are not limited to the specific embodiments above. Accordingly, various modifications, adaptations, and combinations of the features of the described embodiments can be made without departing from the scope of the invention as set forth in the claims.

Claims (16)

1. A control system (20) for a power tool including a motor (12), an implement (14) that outputs a desired motion upon actuation of the motor, a transmission (16) that transmits the motion output by the motor to the implement, and a trigger (30) adapted to be actuated by an operator, wherein a moving part of the transmission or the implement acts as a feedback component of the power tool, the control system (20) comprising:

-an association component (22) associated with both the trigger (30) and the feedback component and having a feedback parameter with an initial value corresponding to a first position of the trigger (30) before actuation and a real-time value that varies in response to both actuation of the trigger (30) and movement of the feedback component, the association component (22) being configured to return the feedback parameter to the initial value when the execution component (14) reaches a position corresponding to a second position of the trigger (30) to which actuation is to take place;

a sensor (24) configured to sense a real-time value of a feedback parameter of the associated component (22), and to generate a first control signal when the real-time value deviates from the initial value and a second control signal when the real-time value returns to the initial value; and

a motor controller (26) in communication with the sensor (24) and configured to switch the motor (12) to an active state in response to receiving the first control signal from the sensor (24) and to switch the motor to an inactive state in response to receiving the second control signal from the sensor (24).

2. The control system (20) of claim 1, wherein each of the first and second positions is an initial position corresponding to the power tool being in a rest state or a trigger position different from the initial position.

3. The control system (20) of claim 2, wherein,

when the trigger (30) is moved from the first position to a second position in a direction away from the initial position, the motor controller (26) causes the motor (12) to output a rotation in a first rotational direction based on receipt of the first control signal; or alternatively

When the trigger (30) is moved from the first position to a second position in a direction toward the initial position, the motor controller (26) causes the motor (12) to output a rotation in a second rotational direction opposite the first rotational direction based on receipt of the first control signal.

4. A control system (20) according to any one of claims 1-3, wherein the associated component (22) is an elastically deformable element, the feedback parameter is an elastic deformation force, and the sensor is a force sensor.

5. The control system (20) of claim 4, wherein said elastically deformable element is a spring.

6. A control system (20) according to any one of claims 1-3, wherein the association means (22) is associated directly or indirectly with the trigger (30) and with the feedback means directly or indirectly via an intermediate means.

7. The control system (20) according to claim 6, wherein the sensor (24) is arranged on the associated component (22), on an end of the trigger (30) abutting the associated component (22), or on an end of the intermediate component or the feedback component abutting the associated component (22).

8. A power tool, comprising:

the control system (20) according to any one of claims 1-7;

the motor (12),

the actuator (14),

the transmission (16), and

the trigger (30), wherein a moving part of the transmission (16) or the actuating part (14) serves as a feedback part of the control system.

9. The power tool of claim 8, wherein the implement (14) is a tool configured for performing a desired operation on a workpiece.

10. The power tool of claim 9, wherein the actuation member (14) rotates and/or translates when the trigger (30) is triggered.

11. An electric shears (100), comprising:

the motor is arranged on the side of the motor,

a fixed blade (116),

a movable blade (118) pivoted relative to the stationary blade (116) between an open position and a closed position;

a transmission means (120) for transmitting the driving force output from the motor to the movable blade (118),

a trigger (130) adapted to be triggered by an operator, and

the control system (20) according to any one of claims 1-7, the movable blade (118) being used as an execution part (14) of the control system, one of the moving parts in the transmission (120) or the movable blade (118) constituting a feedback part of the control system.

12. The electric shears (100) of claim 11, wherein the feedback component has a camming outer surface (142) associated with the associating component, the camming outer surface (142) being designed such that: -returning the feedback parameter of the associated part (22) to an initial value when the movable blade (118) reaches a position corresponding to the second position of the trigger (130).

13. The electric shears (100) according to claim 12, wherein,

the transmission (120) comprises: an output gear (126) directly driving the movable blade (118) to pivot, a bevel gear (122) driving the output gear (126) to rotate; and a shaft (124) that rotates in synchronization with the output gear (126) and the bevel gear (122);

the cam-shaped outer surface (142) is provided by a cam integrally formed with or attached to one of the output gear (126), the bevel gear (122) and the shaft (124).

14. The electric shears according to claim 13, further comprising a slidably disposed pin having one end abutting the cam-shaped outer surface (142) and the other end abutting the associated component (22).

15. The electric shears according to claim 14, wherein the association member (22) is a spring (160) having opposite ends abutting the pin and trigger (130), respectively, and the sensor (24) is a force sensor.

16. The electric shears according to claim 15, wherein the force sensor is provided at an end of the pin abutting a spring (160).