Braking system, braking method and controller for chain saw and chain saw

Abstract

The application provides a braking system for a chainsaw, comprising a sensor unit configured to sense a motion characteristic of the chainsaw; a current detection means for detecting a load current of the chain saw; and a controller. The controller generates a braking signal to control a motor of the chain saw to enter a braking process when the load current meets a current preset condition and the motion characteristic meets a motion characteristic preset condition. The invention further provides a braking method for the chain saw, a controller and the chain saw.

Description

Technical Field

[0001] The present application relates to power tools, and more particularly to braking techniques for chain saws. Background Art

[0002] Figure 1 is a schematic view of a chain saw. As Figure 1 shown, the chain saw includes a housing (not labeled), a front handle baffle 1, a front handle 11, a guide bar 4 and a guide bar cover 2, a saw chain 5, anti-slip teeth 3, a saw chain stop 6, a drive sprocket cover 7, a rear handle baffle 8, a rear handle 9, a power switch 10, and a motor (not shown).

[0003] Compared with a traditional chain saw such as Figure 1 shown, the pruning saw, as a new type of chain saw, has the characteristics of light weight, compact structure, and flexible use. The traditional chain saw is provided with front and rear handles (11, 9) for an operator to hold the chain saw during use. However, for the purpose of being light in weight and compact in structure, the pruning saw usually does not separately provide a front handle, but uses the optimized tool housing as an auxiliary holding part. As a result, the operability of the saw by the operator during use decreases, especially when it is necessary to apply an upward pulling force to prevent the tool from falling, it is difficult to apply force. Summary of the Invention

[0004] According to one aspect of the present application, there is provided a braking system for a chain saw, including a sensor unit configured to sense a motion characteristic of the chain saw; a current detection component configured to detect a load current of the chain saw; and a controller configured to generate a braking signal to control the motor of the chain saw to enter a braking process when the load current meets a current preset condition and the motion characteristic meets a motion characteristic preset condition.

[0005] According to another aspect of the present application, there is also provided a braking method for a chain saw, the method including sensing a motion characteristic of the chain saw by a sensor unit; detecting a load current of the chain saw by a current detection component; generating a braking signal to control the motor of the chain saw to enter a braking process when the load current meets a current preset condition and the motion characteristic meets a motion characteristic preset condition; wherein the sensor unit and the current detection component are provided on the chain saw.

[0006] According to another aspect of the present application, there is also provided a controller. The controller includes a memory and a processor, the memory stores instructions, and the processor is configured to implement any one of the braking methods described herein when executing the instructions.

[0007] The present application also provides a chain saw, including the braking system according to an example of the present application, or executing the braking method according to an example of the present application, or including the controller according to an example of the present application.

[0008] In each of the above examples, the chainsaw can be a compact chainsaw, such as a pruning saw. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The embodiments of the present application will be described in detail below in conjunction with the drawings so that the present application can be more fully understood, where:

[0010] Figure 1 is a schematic diagram of a chainsaw;

[0011] Figure 2 is a schematic structural diagram of an exemplary chainsaw;

[0012] Figure 3 is a schematic structural diagram of a braking system for a chainsaw according to an example of the present application;

[0013] Figure 4 is an exemplary illustration of a motor control circuit;

[0014] Figure 5 is a flowchart of a braking method for a chainsaw according to an example of the present application;

[0015] Figure 6 is a flowchart of a more specific braking method according to an example of the present application;

[0016] Figure 7 is a schematic structural diagram of a controller according to an example of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0017] Figure 2 is a schematic structural diagram of an exemplary compact chainsaw 2. Briefly, the chainsaw includes a housing (not labeled), a motor (not shown) as a driving device, a guide bar 23, a saw chain 24, and a controller (not shown). The compact chainsaw 2 does not have a separate front handle, but uses the protruding part 22 of the housing as an auxiliary handle. In addition to using the protruding part labeled 22 in the figure as the auxiliary handle, other parts of the housing can also be used as the auxiliary handle. As an example, such a compact chainsaw without a separate handle is, for example, a pruning saw.

[0018] Figure 3 is a schematic structural diagram of a braking system 3 for a chainsaw according to an example of the present application. As Figure 3As shown, the braking system 3 includes a sensor unit 30, a current detection component 32, and a controller 34. The sensor unit 30 is configured to sense the motion characteristics of the chainsaw. As an example, the sensor unit 30 may include a gyroscope sensor, where the motion characteristic is the angular velocity of the chainsaw sensed by the gyroscope sensor. The current detection component 32 is configured to detect the load current of the chainsaw. Exemplarily, it can be a current sensor. Both the current detection component 32 and the gyroscope sensor 30 can be arranged within the housing of the chainsaw to sense the load current of the chainsaw control circuit. Generally, during the cutting process, the greater the cutting resistance, the greater the load current of the chainsaw. Alternatively, the current sensor can also be a current acquisition circuit. The controller 34 is configured to generate a braking signal to control the motor of the chainsaw to enter the braking process when the load current detected by the current detection component 32 meets the current preset condition and the motion characteristics sensed by the sensor unit 30 meet the motion characteristic preset condition.

[0019] As an example, the load current meeting the current preset condition means that the load current decreases, and in a further example, the load current meeting the preset condition means that after the load current suddenly decreases, for example, drops to less than the current threshold and remains at a smaller value or gradually becomes smaller within a duration T, where the duration T is, for example, several tens of milliseconds, etc. The motion characteristics meeting the motion characteristic preset condition include the angular velocity increasing to be greater than the angular velocity threshold. When the chainsaw finishes cutting a cutting object such as a tree trunk, the angular velocity will increase due to the sudden reduction or disappearance of the cutting resistance.

[0020] Taking the application of the braking system according to the examples of the present application to a compact chainsaw 2 such as a pruning saw (see Figure 2 ) as an example to further illustrate the present application. In this example, the sensor unit 30 is a gyroscope sensor, the current acquisition component 32 is a current sensor, and the gyroscope sensor is a gyroscope sensor of at least one axis. In the specific example to be described in the present application, it will be taken that the load current I drops to be less than the current threshold I th , and the angular velocity ω is greater than the angular velocity ω th As an example, and the sensor unit 30 includes a gyroscope sensor, and the current detection component 32 is a current sensor. The.

[0021] Specifically, as the chainsaw 2 starts, the current sensor 32 senses the load current I of the motor while the gyroscope sensor 30 senses the angular velocity ω of the motor 38. The controller 34 receives the load current I sensed by the current sensor 32 and the angular velocity ω of the motor 38 sensed by the gyroscope sensor 30. The controller 34 when the load current I changes from high to low to be less than the current threshold I th , and continuously remains less than the current threshold I th for a duration T, and at the same time the angular velocity ω increases to be greater than the angular velocity threshold ω thWhen a braking signal is generated. Alternatively, when the load current I decreases from high to less than the current threshold I th , and at the same time the angular velocity drop ω is greater than the angular velocity threshold ω th , and continuously greater than the angular velocity threshold ω th reaches the duration T, a braking signal is generated. Alternatively, when the load current I decreases from high to less than the current threshold I th and at the same time the angular velocity drop ω is greater than the angular velocity threshold ω th , and when the time for both to be less than their respective thresholds reaches the duration T, the controller 34 generates a braking signal.

[0022] The controller 34 sends this braking signal to the control circuit 36 of the motor to brake the motor 38 through it. The controller 34 can accurately determine the end of the cutting stroke of the chainsaw 2 from the situation where the load current decreases and at the same time the angular velocity increases, and timely control the motor 38 to stop operating. In this way, the operator holding the auxiliary handle 32 does not need to apply a large force to stop cutting, especially when the cutting direction is towards the ground.

[0023] According to some examples of the present application, the controller 34 determines the angular velocity threshold according to the cutting direction of the chainsaw. According to the examples of the present application, a plurality of angular velocity thresholds have been preset, and the preset angular velocity thresholds are related to the cutting direction. Here, the cutting direction may include longitudinal cutting consistent with the direction of gravity, lateral cutting consistent with the horizontal direction, and intermediate directions between the lateral and longitudinal directions. That is to say, when the chainsaw cuts the object along the horizontal direction, it is lateral cutting; when cutting the object along the direction of gravity or along the direction opposite to the direction of gravity, it is longitudinal cutting. The former can be called downward cutting and the latter can be called upward cutting; cutting along other directions refers to cutting along the intermediate direction here. It should be noted that as long as the angle difference between the cutting direction and the direction of gravity is within an allowable deviation of, for example, plus or minus 5 degrees, it can be regarded as the cutting direction being consistent with the direction of gravity; similarly, as long as the angle difference between the cutting direction and the horizontal direction is within an allowable deviation of, for example, plus or minus 5 degrees, it can be considered that the cutting direction is consistent with the horizontal direction.

[0024] For the judgment of the cutting direction, in some cases, it can be determined according to the sensing data of the gyroscope sensor. In other cases, the sensor unit may further include an acceleration sensor. Thus, the sensing data of the acceleration sensor can be combined to further determine the cutting direction of the chainsaw. In still other cases, the sensor unit further includes an image sensor, such as a camera, to obtain the cutting image data of the chainsaw through it and then determine the cutting direction, etc.

[0025] The controller 34 determines the cutting direction of the chainsaw based on the data sensed by the sensor unit 30. The angular velocity threshold can be set differently according to the cutting direction. Specifically, the smaller the angle between the cutting direction and the gravity direction, the smaller the angular velocity threshold can be set. This is mainly because the smaller the angle between the cutting direction and the gravity direction, the easier it is for the chainsaw to rotate rapidly downward due to gravity at the end of cutting, which may injure the operator. Therefore, the braking of the chainsaw should be implemented earlier, and for this purpose, the threshold is set to a value that is easier to reach. When cutting downward in the longitudinal direction, the angle between the cutting direction and the gravity direction is basically 0 degrees. When cutting horizontally, the angle between the cutting direction and the gravity direction is basically 90 degrees. When cutting upward in the longitudinal direction, the angle between the cutting direction and the gravity direction is basically 180 degrees. When the cutting direction is between the horizontal and the downward cutting direction, the cutting angle is greater than 0 degrees and less than 90 degrees. When the cutting direction is between the horizontal and the upward cutting direction, the cutting angle is greater than 90 degrees and less than 180 degrees.

[0026] Figure 4 is an exemplary illustration of the motor control circuit. As Figure 4 shown, the control circuit includes a first electronic switch 41, a second electronic switch 42, a third electronic switch 43, a fourth electronic switch 44, a fifth electronic switch 45, and a sixth electronic switch 46. The first electronic switch 41 and the fourth electronic switch 44 are connected. The second electronic switch 42 and the fifth electronic switch 45 are connected. The third electronic switch 43 and the sixth electronic switch 46 are connected. The three phase lines of the motor 28 are respectively connected between the first electronic switch 41 and the fourth electronic switch 44, between the third electronic switch 43 and the sixth electronic switch 46, and between the second electronic switch 42 and the fifth electronic switch 45. After receiving the braking signal sent by the controller 34, the first electronic switch 41, the third electronic switch 43, and the fifth electronic switch 45 are disconnected, and the second electronic switch 42, the sixth electronic switch 46, and the fourth electronic switch 43 are adjusted according to the operating conditions of the motor to cut off the operation of the motor, that is, to brake the motor and make it stop working.

[0027] Figure 3 The braking system 3 shown can be applied to Figure 2 the compact chainsaw 2 shown. Taking the pruning saw 2 as an example, for a pruning saw 2 without the Figure 2 braking system shown, when longitudinally cutting a tree, at the end of cutting, if the operator is slightly distracted and fails to hold the auxiliary handle 22 well, the pruning saw 1 will rotate rapidly downward under the action of gravity, causing unnecessary losses. After adopting the braking system 3 according to the example of the present application, at the end of cutting, even if the operator is slightly distracted and fails to hold the auxiliary handle 12 well, the controller 38 will accurately determine the end of cutting based on both the decrease in load current and the increase in angular velocity and control the motor to brake, thereby avoiding the situation where the pruning saw 2 rotates rapidly downward under the action of gravity.

[0028] In the examples of this application, the motion characteristics of the chainsaw are characterized by the angular velocity and the load current. However, other quantities can also be used to characterize the motion characteristics of the chainsaw, such as the angular acceleration of the chainsaw. Accordingly, the sensor unit for sensing the motion characteristics may include other components or settings not mentioned herein to obtain other quantities characterizing the motion characteristics.

[0029] Figure 5 is a flowchart of a braking method for a chainsaw according to an example of this application. As Figure 5 shown, in step S400, the motion characteristics of the chainsaw are sensed by the sensor unit. In step S402, the load current of the chainsaw is detected by the current detection component. In step S404, when the load current meets the current preset condition and the motion characteristics meet the motion characteristic preset condition, a braking signal is generated to control the motor of the chainsaw to enter the braking process.

[0030] This method can be executed by Figure 3 the braking system for the chainsaw shown. Specifically, the motion characteristics of the chainsaw are sensed (S400) by the sensor unit 30. The load current of the chainsaw is detected (S402) by the current detection component 32. For example, the load current of the chainsaw is sensed by the current sensor. The controller 34 generates (S404) a braking signal to control the motor of the chainsaw to enter the braking process when the load current meets the current preset condition and the motion characteristics meet the motion characteristic preset condition.

[0031] Figure 6 is a flowchart of a more specific braking method according to an example of this application, which is executed by Figure 3 the braking system shown, and in this example, the cutting direction takes the horizontal and vertical directions as examples. The following will refer to Figure 3 to elaborate on this method.

[0032] In step S500, the angular velocity of the chainsaw is sensed by the gyroscope sensor 30, and the sensed angular velocity is transmitted to the controller 34. In step S502, the load current of the chainsaw is sensed by the current sensor 32, and the sensed load current is transmitted to the controller 34. In step S504, the controller 34 determines the cutting direction of the chainsaw. The controller 34 determines the cutting direction based on, for example, the sensing data of the gyroscope sensor. In some other cases, the sensing data of the acceleration sensor or the imaging sensor may also be combined to determine whether the cutting direction of the chainsaw is horizontal or vertical. When it is determined in step S504 that the cutting direction of the chainsaw is horizontal, the process proceeds to step S508. When it is determined in step S506 that the cutting direction of the chainsaw is vertical, the process proceeds to step S510. In step S508, the controller 34 compares the load current with the current threshold and compares the load angular velocity with the angular velocity threshold in the horizontal cutting scenario. In step S509, the controller 34 determines whether the comparison results in step S508 simultaneously satisfy the conditions that the load current is less than the load current threshold and the load angular velocity is greater than the angular velocity threshold. If so, the process proceeds to step S520, where the controller 34 generates a braking signal and sends it to the motor control circuit 36 to implement braking of the motor 38. If not, the comparison results in step S508 are continuously obtained. In step S510, the controller 34 compares the load current with the current threshold and compares the load angular velocity with the angular velocity threshold in the vertical cutting scenario. In step S512, the controller 34 determines whether the comparison results in step S510 simultaneously satisfy the conditions that the load current is less than the load current threshold and the angular velocity is greater than the angular velocity threshold. If so, the process proceeds to step S520, where the controller 34 generates a braking signal and sends it to the motor control circuit 36 to implement braking of the motor 38. If not, the comparison results in step S510 are continuously obtained.

[0033] The present application also provides a controller, Figure 7 which is a schematic structural diagram of the controller. As Figure 7 shown, the controller includes a memory 70 and a processor 72. The memory 70 stores instructions, and when the processor 72 is configured to execute the instructions, the braking method described in any one of the above examples is implemented. For example, when the processor 72 executes these instructions, the controller generates a braking signal to control the motor of the chainsaw including the controller to enter the braking process when the load current meets the current preset condition and the motion characteristics meet the motion characteristic preset condition. The controller can be implemented, for example, in Figure 3 the braking system as part of the controller 34 or as an alternative to the controller 34. In some other examples, the controller can be disposed in Figure 2 the chainsaw shown.

[0034] According to an example of the present application, a chainsaw is also provided. The chainsaw includes any one of the braking systems according to the examples of the present application, or performs any one of the braking methods according to the examples of the present application, or includes a controller according to the examples of the present application. In a more specific example, the chainsaw is, for example, a pruning saw.

[0035] Without contradiction or conflict, the technical features in the various examples described herein can be combined with each other to form embodiments not described herein, and these embodiments should also be covered by the scope of the present application.

[0036] Although specific embodiments of the present application have been shown and described in detail to illustrate the principles of the present application, it should be understood that the present application can be implemented in other ways without departing from such principles. For example, the technical features of the various embodiments / examples of the present application can be combined with each other to form new embodiments.

Claims

1. A braking system (3) for a chainsaw, characterized in that, Comprising: A sensor unit (30) configured to sense the motion characteristics of the chain saw; A current detection component (32) configured to detect the load current of the chain saw; A controller (34) configured to generate a braking signal to control the motor of the chain saw to enter a braking process when the load current meets a current preset condition and the motion characteristics meet a motion characteristic preset condition.

2. The braking system (3) according to claim 1, characterized in that, The load current meeting the current preset condition includes the load current decreasing to be less than a current threshold, and the motion characteristics meeting the motion characteristic preset condition includes the angular velocity increasing to be greater than an angular velocity threshold.

3. The braking system according to claim 2, characterized in that, The controller (34) is configured to generate the braking signal when the duration that the load current is less than the current threshold reaches a duration T and / or the duration that the angular velocity is greater than the angular velocity threshold reaches the duration T.

4. The braking system according to claim 2, wherein, The controller (34) is further configured to determine the angular velocity threshold according to the cutting direction of the chain saw.

5. The braking system according to claim 4, characterized in that, The cutting direction includes a lateral direction substantially perpendicular to the direction of gravity, a longitudinal direction perpendicular to the lateral direction, and an intermediate direction between the lateral and longitudinal directions; and, the smaller the angle between the cutting direction and the direction of gravity, the smaller the angular velocity threshold.

6. The braking system according to any one of claims 1 to 5, characterized in that, The current detection component (32) is a current sampling circuit or a current sensor.

7. The braking system according to any one of claims 1 to 5, characterized in that, The sensor unit (30) includes a gyroscope sensor.

8. The braking system according to claim 7, characterized in that, The sensor unit (30) may further include an acceleration sensor and / or an image sensor.

9. A braking method for a chainsaw, characterized in that, The method includes: Sensing the motion characteristics of the chain saw by a sensor unit; Detecting the load current of the chain saw by a current detection component; Generating a braking signal to control the motor of the chain saw to enter a braking process when the load current meets a current preset condition and the motion characteristics meet a motion characteristic preset condition; Wherein, the sensor unit and the current detection component are arranged on the chain saw.

10. The braking method according to claim 9, characterized in that, The load current meeting the current preset condition includes the load current decreasing to be less than a current threshold, and the motion characteristics meeting the motion characteristic preset condition includes the angular velocity increasing to be greater than an angular velocity threshold.

11. The braking method according to claim 10, wherein The load current meeting the current preset condition and the motion characteristics meeting the motion characteristic preset condition includes: generating the braking signal when the duration that the load current is less than the current threshold reaches a duration T and / or the duration that the angular velocity is greater than the angular velocity threshold reaches the duration T.

12. The braking method according to claim 10, characterized in that, The angular velocity threshold is determined according to the cutting direction of the chain saw.

13. The braking method according to claim 12, characterized in that, The cutting direction includes a lateral direction substantially perpendicular to the direction of gravity, a longitudinal direction perpendicular to the lateral direction, and an intermediate direction between the lateral and longitudinal directions; and, the smaller the angle between the cutting direction and the direction of gravity, the smaller the angular velocity threshold.

14. A controller, which includes a memory and a processor, the memory stores instructions, and the processor is configured to, when executing the instructions, implement the braking method according to any one of claims 9 to 13.

15. A chain saw, which includes the braking system according to any one of claims 1 to 8, or executes the braking method according to any one of claims 9 to 13, or includes the controller according to claim 14.

16. In the braking system according to any one of claims 1 to 8, or in the braking method according to any one of claims 9 to 13, or in the chainsaw according to claim 14, characterized in that, The chain saw is a pruning saw.

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