Electric pruning shears and control method thereof

Abstract

The invention discloses a pair of electric pruning shears which comprises a blade, a motor and a controller, the controller controls the blade to conduct cutting action through the motor, the controller is provided with a control circuit, and the motor responds to the situation that the control circuit detects that the cutting load is increased to reduce the cutting force applied to the blade so that the blade can stop cutting. And when the cutting load returns to normal, the cutting force applied to the blade is increased, so that the blade continuously performs the cutting action. The controller senses whether the blade of the pruner is clamped or not and whether locked-rotor is relieved or not, and outputs a signal to the motor according to the sensing result to control the motor to reduce or increase the output, so that the blade does not continue to apply shear force during locked-rotor and only keeps the cutting trend, and cutting continues after locked-rotor is relieved. And normal continuous work can be realized without restarting the machine.

Description

Technical Field

[0001] This invention relates to the field of electric garden tools, and in particular to an electric pruning shear and its control method. Background Technology

[0002] Electric pruning shears, also known as hedge trimmers, are power tools widely used in agriculture and landscaping. During use, pruning shears often cut branches with a diameter larger than the machine's maximum diameter, causing the blades to jam and become unable to cut properly. The following two methods are commonly used to address this issue: 1. After the machine stalls and jams, manually shut down the machine, release the power supplied to the blades, then manually remove the stalled material from the blades, and then restart the machine.

[0003] 2. When the machine stalls and gets stuck, the controller will reverse the motor to automatically retract the blades, thereby relieving the force on the stalled material and making it easier for the stalled material to come off. However, the machine needs to be restarted before it can be cut normally.

[0004] Both of the above solutions require restarting the machine to continue working normally, which not only results in low work efficiency and a poor user experience, but also causes the motor starting current to surge, affecting the lifespan of the motor and electronic components. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by proposing an electric pruning shear and its control method, which can continue to work normally without restarting the machine after the stall is cleared.

[0006] The technical solution to achieve the objective of this invention is: An electric pruning shear includes a blade, a motor, and a controller. The controller controls the blade to perform a cutting action via the motor. The controller is provided with a control circuit. The motor reduces the cutting force applied to the blade in response to the control circuit detecting an increase in cutting load, so that the blade stops cutting. When the cutting load returns to normal, the cutting force applied to the blade is increased so that the blade continues to perform the cutting action.

[0007] Furthermore, the control circuit includes a main control unit and a current detection circuit, a motor drive circuit, and a timing circuit, all electrically connected to the main control unit. When the cutting load increases, the current detection circuit detects that the current drawn into the motor exceeds a set threshold and starts the timing circuit. When the time recorded by the timing circuit exceeds a first set threshold, the main control unit controls the motor drive circuit to reduce the output current, so that the motor applies a cutting force to the blade to stop the blade from cutting and maintain the trend of continuing to cut.

[0008] Furthermore, if the current detection circuit detects that the current drawn into the motor exceeds a set threshold and the time recorded by the timing circuit exceeds a second set threshold, the main control unit controls the motor drive circuit to disconnect from the motor so that the motor stops running. The second set threshold is greater than the first set threshold.

[0009] Furthermore, the control circuit also includes a status indication circuit electrically connected to the main control unit. The status indication circuit is equipped with an LED indicator or a buzzer. The LED indicator and the buzzer are configured to exhibit different states when the current exceeds a set threshold and when the time reaches a first set threshold and a second set threshold, respectively.

[0010] Furthermore, the first set threshold is 5 seconds, and the second set threshold is 10 minutes.

[0011] Furthermore, the main control unit is electrically connected to a temperature sensor, which is installed on the windings or housing of the motor to provide an overheat protection signal.

[0012] Furthermore, the motor drive circuit is an H-bridge drive circuit that supports PWM modulation to achieve multi-level torque output.

[0013] Furthermore, it also includes an overload protection unit, which is connected in series between the control circuit and the power supply.

[0014] Furthermore, the power source is a lithium battery.

[0015] A control method for electric pruning shears as described above, characterized by comprising the following steps: Step S1: Obtain the current status of the pruning shears; Step S2: When the pruning shears are in a stalled state, the controller reduces the output current. If the stalled object is removed within 5 seconds, the pruning shears will operate normally. Otherwise, the controller will continue to reduce the output current to keep the blade cutting and stop cutting. Step S3: Continue to remove the blockage and automatically stop the machine after 10 minutes.

[0016] By adopting the above technical solution, the present invention has the following beneficial effects: (1) The present invention uses a controller to sense whether the blade of the pruning machine is stuck and whether the stall is released, and outputs a signal to the motor based on the sensing result to control the motor to reduce or increase the output. This achieves that when the stall is released, the blade will not continue to apply clamping shearing force, but only maintains the cutting trend, and continues to cut after the stall is released. The machine can work normally and continuously without restarting.

[0017] (2) The controller of the present invention detects the magnitude of the current drawn into the motor through the current detection circuit, thereby determining whether the blade is stalled, and records the stall time synchronously through the timing circuit. When the stall reaches a certain time, the motor output is reduced. This fully considers that when partial stall occurs, the problem can be solved by simply swinging the instrument, without immediately adjusting the motor output to the minimum, which is more conducive to restarting the cutting action. When the stall exceeds the set time, the motor output is adjusted to a smaller value, which is more in line with the actual work requirements.

[0018] (3) The timing circuit of the present invention has a second threshold that is greater than the first threshold. When the time reaches the second threshold, the output of the motor drive circuit is zero, which avoids the difficulty in releasing the stall and the motor overheating and being damaged due to maintaining a low current for a long time, thus improving safety.

[0019] (4) By adding a status indicator circuit, the present invention can intuitively show the operator the current status of the machine, so as to facilitate manual intervention in case of emergencies.

[0020] (5) The present invention is equipped with a temperature sensor to detect the motor temperature, which provides double protection. When the motor temperature is too high, the controller will control the motor to stop output immediately to protect the motor.

[0021] (6) The present invention adds an overload protection unit to prevent the motor from being damaged when the controller fails and the motor output cannot be controlled.

[0022] (7) The present invention uses a lithium battery to power the whole machine, which reduces the weight of the whole machine and reduces user fatigue. Attached Figure Description

[0023] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein: Figure 1 This is a schematic diagram of the controller structure of the present invention; Figure 2 This is the judgment logic diagram of the present invention.

[0024] The labels in the attached diagram are: 1. Main control unit; 2. Current detection circuit; 3. Motor drive circuit; 4. Timing circuit; 5. Status indication circuit; 6. Temperature sensor. Detailed Implementation

[0025] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0026] This embodiment provides an electric pruning shear, including blades, a motor, a controller, and a lithium battery. The lithium battery powers the entire machine, reducing its weight and user fatigue. The controller controls the blades via the motor to perform the cutting action. The controller has a control circuit; when the control circuit detects an increase in cutting load, the motor reduces its output torque, thereby reducing the cutting force applied to the blades and stopping the cutting. When the control circuit detects that the cutting load has returned to normal, the motor increases its output torque, applying cutting force to the blades and allowing them to continue cutting. The entire process does not require restarting the machine, avoiding frequent start-up and stop cycles that could cause starting current surges in the motor and extending the lifespan of the motor and electronic components.

[0027] Specifically, such as Figure 1 As shown, the control circuit includes a main control unit 1, a current detection circuit 2, a motor drive circuit 3, and a timing circuit 4, all of which are electrically connected to the main control unit 1. The motor drive circuit 3 is an H-bridge drive circuit that supports PWM modulation to achieve multi-level torque output.

[0028] The judgment logic diagram of this embodiment is as follows: Figure 2 As shown, when the cutting load increases, the current detection circuit 2 detects that the current drawn into the motor exceeds the set threshold. First, the main control unit 1 controls the motor drive circuit 3 to output a smaller current, and simultaneously starts the timing circuit 4. When the time recorded by the timing circuit 4 exceeds the first set threshold (set to 5 seconds), the main control unit 1 controls the motor drive circuit 3 to further reduce the output current. This current causes the motor to apply a very small cutting force to the blade, which only maintains the tendency to continue cutting, thus stopping the cutting process. When the time recorded by the timing circuit 4 exceeds the second set threshold (set to 10 minutes), the main control unit 1 controls the motor drive circuit 3 to disconnect from the motor, causing the motor to stop running. This structural design fully considers that when partial stall occurs, simply swinging the device can resolve the issue; that is, the stall is relieved within 5 seconds without immediately adjusting the motor output to the minimum. When the stall exceeds 5 seconds, the motor output is further reduced. At 10 minutes, regardless of whether the stall is relieved, the motor output is zero, avoiding the risk of overheating and damage due to prolonged low current operation caused by stalling or delayed retrieval. This improves safety and better meets actual work requirements.

[0029] The control circuit also includes a status indication circuit 5 electrically connected to the main control unit 1. The status indication circuit 5 is equipped with an LED indicator or a buzzer. The LED indicator and buzzer are configured to display different states when the current exceeds a set threshold and when the time reaches a first set threshold and a second set threshold, respectively. This visually indicates the current status of the machine to the operator, facilitating manual intervention in case of emergencies. Therefore, the motor drive circuit 3 in this embodiment is configured with a control button. When the button is pressed, automatic control is disabled, and the motor drive circuit 3 directly controls the motor to reverse one revolution. At this time, manual intervention is required to release the stall.

[0030] To further enhance circuit safety, the main control unit 1 in this embodiment is electrically connected to a temperature sensor 6. The temperature sensor 6 is located on the motor windings or housing and provides an overheat protection signal. When the motor temperature is too high, the controller immediately stops the motor output to protect it. Furthermore, an overload protection unit, which can be a fuse, is connected in series between the control circuit and the power supply to prevent damage to the motor in case of controller failure.

[0031] This invention uses a controller to sense whether the blades of the pruning machine are stuck and whether the stall has been released. The sensing result outputs a signal to the motor, which controls the motor to reduce or increase the output. This ensures that the blades will not continue to apply clamping shearing force when stalled, but only maintain the cutting trend. After the stall is released, cutting continues. The machine can work normally and continuously without restarting. At the same time, it retains the function of manually controlling the motor to reverse via a button, which can meet the usage habits of different operators.

[0032] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An electric pruning shears, comprising blades, a motor, and a controller, wherein the controller controls the blades to perform cutting actions via the motor, and the controller is provided with a control circuit, characterized in that: The motor reduces the cutting force applied to the blade in response to the control circuit detecting an increase in cutting load, so that the blade stops cutting, and increases the cutting force applied to the blade when the cutting load returns to normal, so that the blade continues to perform cutting action.

2. The electric pruning shears according to claim 1, characterized in that: The control circuit includes a main control unit and a current detection circuit, a motor drive circuit, and a timing circuit, all electrically connected to the main control unit. When the cutting load increases, the current detection circuit detects that the current drawn into the motor exceeds a set threshold and starts the timing circuit. When the time recorded by the timing circuit exceeds a first set threshold, the main control unit controls the motor drive circuit to reduce the output current, so that the motor applies a cutting force to the blade to stop cutting and maintain the trend of continuing to cut.

3. The electric pruning shears according to claim 2, characterized in that: The current detection circuit detects that the current drawn into the motor exceeds a set threshold and the time recorded by the timing circuit exceeds a second set threshold. The main control unit controls the motor drive circuit to disconnect from the motor so that the motor stops running. The second set threshold is greater than the first set threshold.

4. The electric pruning shears according to claim 3, characterized in that: The control circuit also includes a status indicator circuit electrically connected to the main control unit. The status indicator circuit is equipped with an LED indicator or a buzzer. The LED indicator and the buzzer are configured to present different states when the current exceeds a set threshold and when the time reaches a first set threshold and a second set threshold, respectively.

5. The electric pruning shears according to claim 3, characterized in that: The first set threshold is 5 seconds, and the second set threshold is 10 minutes.

6. The electric pruning shears according to claim 3, characterized in that: The main control unit is electrically connected to a temperature sensor, which is installed on the windings or housing of the motor and is used to provide an overheat protection signal.

7. The electric pruning shears according to claim 3, characterized in that: The motor drive circuit is an H-bridge drive circuit that supports PWM modulation to achieve multi-level torque output.

8. The electric pruning shears according to claim 3, characterized in that: It also includes an overload protection unit, which is connected in series between the control circuit and the power supply.

9. An electric pruning shears according to claim 8, characterized in that: The power source is a lithium battery.

10. A control method for electric pruning shears as described in any one of claims 1 to 9, characterized in that, Includes the following steps: Step S1: Obtain the current status of the pruning shears; Step S2: When the pruning shears are in a stalled state, the controller reduces the output current. If the stalled object is removed within 5 seconds, the pruning shears will operate normally. Otherwise, the controller will continue to reduce the output current to keep the blade cutting and stop cutting. Step S3: Continue to remove the blockage and automatically stop the machine after 10 minutes.

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