Power tool and control method

Abstract

The present application relates to a kind of electric tools, control module acquires the data of two sensors of sensing module in a certain time, and respectively calculates corresponding first, second parameter, if simultaneously satisfy the condition that first parameter is less than or equal to first parameter threshold value, and second parameter is less than or equal to second parameter threshold value, then judge two sensors to be normal state, if cannot simultaneously satisfy the condition, then judge two sensors abnormal, control tool stops running;When judging two sensors to be normal state, the difference between the data of two sensors is calculated, if difference is less than difference threshold value, then control tool continues to run, repeat above judgment;If difference is greater than or equal to difference threshold value, then control tool stops running.The present application patent is by calculating and comparing the relationship of two sensors own parameter and threshold value and the relationship of two sensor difference and threshold value, ensure that the temperature of each MOS transistor can be collected simultaneously and also ensure that temperature sensor itself keeps normal state in the whole working process.

Description

Technical Field

[0001] This invention relates to the field of power tools, and particularly to a power tool and a control method thereof. Background Technology

[0002] With the widespread use of power tools, users have increasingly higher performance requirements. One issue that frequently needs attention during power tool use is the overheating of MOSFETs on the circuit board. As a key component driving the motor, MOSFETs generate a significant amount of heat during operation. Excessive temperature can easily cause them to break down, thus requiring real-time temperature monitoring. Current power tools typically use a single NTC (Network Temperature Controller) to collect the temperature near the MOSFET. When the NTC temperature reaches a set threshold, the tool shuts off, entering a temperature protection state. However, in this scenario, some MOSFETs may be far from the NTC and may have exceeded the set temperature without being detected by the NTC, potentially damaging the MOSFET. Furthermore, temperature protection settings include both temperature and time limits. If the NTC data fluctuates at a certain point in time, but the data collection time has not reached the manually set time, the tool may continue to run. In this case, the NTC is already malfunctioning, and prolonged use can lead to burn-out. Therefore, multiple NTCs need to be placed near the MOSFETs to ensure that the temperature of each MOSFET can be collected, while simultaneously ensuring that the NTCs themselves remain in normal operating condition throughout the entire operation.

[0003] Please refer to Chinese Invention Patent No. CN102555727B, published on January 28, 2015, which discloses a method for detecting and handling faults using a microprocessor. When thermistors 10 and 11 have the same temperature and / or when thermistors 10 and 11 have a temperature difference within a predetermined threshold, the microprocessor determines that normal operation is normal; when thermistors 10 and 11 have a temperature difference greater than the predetermined temperature difference threshold and / or when the temperature read by thermistor 10 or 11 is greater than a predetermined (maximum) temperature, the microprocessor 24 determines that a fault exists. However, this detection method can only determine whether the tool needs temperature protection, but it cannot solve the problem of incorrect judgments due to damage to the thermistors themselves, leading to the inability to perform temperature protection when temperatures are abnormal. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of this invention is to provide an electric tool and control method that can acquire the temperature of each MOSFET while ensuring that the NTC itself remains in normal condition throughout the entire operation.

[0005] The technical solution adopted by this invention to solve the problems of the prior art is as follows: a power tool, including a switch module, a control module electrically connected to the switch module, and a sensing module connected to the control module. The control module collects data from the sensing module. The sensing module includes a first sensor and a second sensor. The control module collects data from the first sensor and the second sensor within a certain period of time, and calculates a first parameter corresponding to the data from the first sensor and a second parameter corresponding to the data from the second sensor, respectively. If the first parameter is less than or equal to a first parameter threshold and the second parameter is less than or equal to a second parameter threshold, the control module determines that the two sensors are in a normal state. If the conditions cannot be met simultaneously, the control module determines that the two sensors are abnormal and controls the power tool to stop running. After the control module determines that the two sensors are in a normal state, it calculates the difference between the data from the two sensors. If the difference is less than a difference threshold, the control module controls the power tool to continue running and repeats the above judgment. If the difference is greater than or equal to the difference threshold, the control module controls the power tool to stop running.

[0006] A further improvement is as follows: the sensing module is a temperature sensing module, and both the first and second sensors are temperature sensors; the first parameter and the second parameter are respectively the first variance and the second variance, and the threshold values ​​of the first parameter and the second parameter are respectively the first variance threshold value and the second variance threshold value.

[0007] A further improvement is as follows: the control module collects the temperatures T11, T12, ... T1N from the first temperature sensor and the temperatures T21, T22, ... T2N from the second temperature sensor, where N is the number of temperature data collected by the control module.

[0008] A further improvement is as follows: the control module calculates the variance of the temperatures of the first and second temperature sensors using the following formula: Where X is the average value of temperatures T11, T12, ..., T1N or the average value of temperatures T21, T22, ..., T2N, and X1 is the average value of T11 or T21, ..., X N It is either T1N or T2N.

[0009] A further improvement is that the control module stores the first variance threshold. and the second variance threshold If the first variance calculated by the control module Greater than the first variance threshold Or the second variance Greater than the second variance threshold If the control module determines that the temperature data has a high dispersion, it indicates that either the first temperature sensor or the second temperature sensor is damaged, and the control module will then control the power tool to stop operating.

[0010] A further improvement is as follows: the control module calculates the temperature difference ΔT between the first and second temperature sensors using the formula: ΔT=|T1N-T2N|; the difference threshold TN is calculated using the formula: TN=|((T1N+T2N) / 2-25) / K|+T err Where K is the temperature rise coefficient of the two sensors, and T err The offset of the two sensors is their own offset.

[0011] A further improvement is as follows: the control module is also connected to an alarm module, which includes a buzzer. When the difference ΔT is less than the difference threshold TN, the control module controls the power tool to continue running. When the difference ΔT is greater than or equal to the difference threshold TN, the control module controls the power tool to stop running and triggers an alarm via the buzzer.

[0012] The present invention can also solve the problems of the prior art by adopting the following technical solution: a power tool control method, the control method comprising:

[0013] The control module collects data from the first and second sensors;

[0014] The corresponding first parameter and second parameter are calculated based on the data from the first sensor and the second sensor;

[0015] The first parameter is compared with the first parameter threshold, and the second parameter is compared with the second parameter threshold;

[0016] When the first parameter is less than or equal to the first parameter threshold and the second parameter is less than or equal to the second parameter threshold, the control module determines that the two sensors are in a normal state; otherwise, it determines that the two sensors are abnormal and controls the power tool to stop running.

[0017] When the control module determines that the two sensors are in normal condition, it calculates the difference between the data of the two sensors. If the difference is less than the difference threshold, the control module controls the power tool to continue running and repeats the above judgment. If the difference is greater than or equal to the difference threshold, the control module controls the power tool to stop running.

[0018] A further improvement is as follows: both the first and second sensors are temperature sensors, and the control module collects the temperatures T11, T12, ... T1N of the first temperature sensor and the temperatures T21, T22, ... T2N of the second temperature sensor, where N is the number of temperature data collected by the control module.

[0019] A further improvement is that the first parameter threshold, the second parameter threshold, and the difference threshold are all pre-stored in the control module. Attached Figure Description

[0020] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings:

[0021] Figure 1 This is a complete drawing of the power tool of the present invention;

[0022] Figure 2 This is a circuit board diagram of the power tool of the present invention;

[0023] Figure 3 This is a partial circuit diagram of the power tool of the present invention;

[0024] Figure 4 This is a control flowchart of the power tool of the present invention;

[0025] Power tool 100 Housing 1

[0026] Working head 2, Fan 3

[0027] Control module 4, drive module 5

[0028] Locking switch 6 Start / stop switch 7

[0029] First sensor 8 Second sensor 9

[0030] Head shell 11 Postcarpal shell 12

[0031] Grip part 13 Locking shaft 111

[0032] Air inlet 121 Air outlet 122

[0033] Battery pack 200 Detailed Implementation

[0034] The terminology used in this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. For example, terms such as "upper," "lower," "front," and "rear" that indicate orientation or positional relationship are based solely on the orientation or positional relationship shown in the accompanying drawings and are used only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device / element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention.

[0035] Please see Figure 1 The diagram shown is an overall view of the power tool of the present invention. In this invention, the power tool 100 is a polishing machine, which is widely used in decoration, construction and other fields. The polishing machine 100 includes a housing 1, a switch module disposed on the housing 1, and a battery pack 200 connected to the housing 1. The housing 1 includes a head shell 11, a rear shell 12 connected to the head shell 11, and a gripping part 13 supporting the head shell 11 and the rear shell 12.

[0036] The head housing 11 is provided with a locking shaft 111, which is used to connect the working head 2 to the head housing 11. The rear housing 12 has an air outlet 122 and an air inlet 121. A gearbox (not shown) is provided inside the rear housing 12. The gearbox is used to drive the power tool 100 to work. The gearbox is connected to a fan 3. When the fan 3 works, external air enters the rear housing 12 through the air inlet 121 to dissipate heat from the gearbox and blows the heat generated by the gearbox out through the air outlet 122. The bottom of the grip 13 is connected to the battery pack 200, which is used to power the power tool 100.

[0037] The switch module includes a locking switch 6 and a start / stop switch 7. The locking switch 6 is toggled by the user and can be stopped at the left, right, and middle positions. When the locking switch 6 is in the middle position, the start / stop switch 7 is locked and cannot be pressed. When the locking switch 6 is in the left or right position, the start / stop switch 7 can be pressed, causing the power tool 100 to work.

[0038] Please see Figure 2 and Figure 3The diagram shows a circuit board diagram and partial circuit diagram of the power tool of the present invention. The circuit board includes a control module 4, a drive module 5 connected to the control module 4, and a sensing module. The drive module 5 includes six field-effect transistors (FETs). The control module 4 controls the conduction sequence of the six FETs to drive the motor and collect data from the sensing module. The sensing module includes a first sensor 8 and a second sensor 9. The first sensor 8 and the second sensor 9 are used to sense the data from the six FETs. The first sensor 8 and the second sensor 9 are respectively disposed on both sides of the six FETs to ensure that the data from all six FETs can be sensed by the two sensors. The first sensor 8 is connected in series with a first resistor R1, and the second sensor 9 is connected in series with a second resistor R2. The first sensor 8 and the first resistor R1 form a first voltage divider circuit, and the second sensor 9 and the second resistor R2 form a second voltage divider circuit. The control module 4 collects the voltage division values ​​of the two voltage divider circuits.

[0039] In this embodiment, the sensing module is a temperature sensing module. The first sensor 8 and the second sensor 9 are both temperature sensors, preferably NTC thermistors. The two NTC thermistors are used to sense the temperature of the six field-effect transistors. When the temperature of the six field-effect transistors changes over time, the resistance of the two NTC thermistors also changes, and the voltage division values ​​of the two voltage divider circuits collected by the control module 4 also change. The control module 4 internally stores temperature values ​​corresponding to different voltage division values.

[0040] Please see Figure 4 The diagram shows the control flowchart of the power tool of the present invention. In this invention, when the power tool 100 is plugged into the battery pack 200, the battery pack 200 supplies power to the power tool 100. The control module 4 monitors the temperatures of the two temperature sensors and collects the temperature data of the two temperature sensors within a certain period of time. The control module 4 collects the temperatures T11, T12, ... T1N of the first temperature sensor and the temperatures T21, T22, ... T2N of the second temperature sensor, where N is the number of temperature data collected by the control module 4. The control module 4 uses the variance formula... Calculate the variance of the temperature data from the two temperature sensors, where X is the average value of temperatures T11, T12, ..., T1N or the average value of T21, T22, ..., T2N, and X1 is the variance of T11 or T21, ..., X N It is either T1N or T2N.

[0041] The control module 4 also stores a first variance threshold. Second variance threshold If the first variance calculated by the control module 4 Greater than the first variance threshold Or the second variance Greater than the second variance threshold If the control module 4 determines that the temperature data has a high variance, it indicates that either the first temperature sensor or the second temperature sensor is damaged. The control module 4 then controls the power tool 100 to stop operating. If the first variance is also satisfied... Less than or equal to the first variance threshold And the second variance Less than or equal to the second variance threshold If the conditions are met, the control module 4 determines that the two sensors are in a normal state.

[0042] When the control module 4 determines that the two sensors are in normal condition, the control module 4 calculates the difference ΔT between the two sensors using the formula ΔT=|T1N-T2N|. The control module 4 also stores a difference threshold TN, and the formula for calculating the difference threshold TN is: TN=|((T1N+T2N) / 2-25) / K|+T err Where K is the temperature rise coefficient of the two sensors, and T err In this embodiment, K and T represent the offsets of the two sensors themselves. err Both are set to 5. For example, when T11 is 0℃ and T21 is 2℃, TN is 9.8 and ΔT is 2. If the difference ΔT is less than the difference threshold TN, the control module 4 controls the power tool 100 to continue running and repeats the above judgment; if the difference ΔT is greater than or equal to the difference threshold TN, the control module 4 controls the power tool 100 to stop running. The control module 4 is also connected to an alarm module (not shown in the figure). The alarm module includes a buzzer. When the difference ΔT is greater than or equal to the difference threshold TN, the control module 4 controls the power tool 100 to stop running and alarms through the buzzer.

[0043] The power tool of this invention collects temperature data from two temperature sensors through a control module, calculates the variance and compares it with a variance threshold, and calculates the difference between the two temperature sensors and compares it with a difference threshold. This ensures that the control module can collect the temperature of each MOSFET, while also ensuring that the temperature sensor itself remains in normal condition throughout the entire operation.

[0044] This invention is not limited to the specific embodiments described above. Those skilled in the art will readily understand that many alternative solutions exist for the control method of this invention without departing from its principles and scope. The scope of protection of this invention is defined by the claims.

Claims

1. A power tool, comprising a switch module, a control module electrically connected to the switch module, a sensing module and a drive module connected to the control module, wherein the control module controls the drive module to drive a motor and collects data from the sensing module; characterized in that: The sensing module senses the temperature of the drive module. The sensing module includes a first sensor and a second sensor, both of which are temperature sensors. The control module collects data from the first sensor and the second sensor within a certain period of time and calculates a first parameter corresponding to the data from the first sensor and a second parameter corresponding to the data from the second sensor. If both the first parameter and the second parameter are less than or equal to a first parameter threshold, and the second parameter is less than or equal to a second parameter threshold, the control module determines that the two sensors are in a normal state. If the conditions are not met simultaneously, the control module determines that the two sensors are abnormal and controls the power tool to stop running. After the control module determines that the two sensors are in a normal state, it calculates the difference between the data from the two sensors. If the difference is less than a difference threshold, the control module controls the power tool to continue running and repeats the above judgment. If the difference is greater than or equal to the difference threshold, the control module controls the power tool to stop running. The difference threshold is a function of the data from the first sensor and the data from the second sensor.

2. The power tool according to claim 1, characterized in that: The first parameter and the second parameter are the first variance and the second variance, respectively, and the first parameter threshold and the second parameter threshold are the first variance threshold and the second variance threshold, respectively.

3. The power tool according to claim 2, characterized in that: The control module collects the temperature from the first sensor. , … and the temperature of the second sensor , … Where N is the number of data points collected by the control module.

4. The power tool according to claim 3, characterized in that: The control module calculates the variance of the temperatures of the first and second sensors using the following formula: Where X is temperature , … average or , … The average value, for or , ..., for or .

5. The power tool according to claim 4, characterized in that: The control module stores the first variance threshold. and the second variance threshold ; If the first variance calculated by the control module Greater than the first variance threshold Or the second variance Greater than the second variance threshold If the control module determines that the data dispersion is too high, it indicates that either the first sensor or the second sensor is damaged, and the control module controls the power tool to stop operating.

6. The power tool according to claim 3, characterized in that: The control module calculates the temperature difference between the first and second sensors. The formula is: The difference threshold The calculation formula is: Where K is the temperature rise coefficient of the first and second sensors. This represents the offset of the first and second sensors themselves.

7. The power tool according to claim 6, characterized in that: The control module is also connected to an alarm module, which includes a buzzer. When the difference... Less than the difference threshold At that time, the control module controls the power tool to continue operating, and when the difference... Greater than or equal to the difference threshold When this occurs, the control module controls the power tool to stop operating and triggers an alarm via the buzzer.

8. A power tool control method, characterized in that: The control method includes: The control module collects data from the first sensor and the second sensor. Both the first and second sensors are temperature sensors, which sense the temperature of the drive module used to drive the motor. The corresponding first parameter and second parameter are calculated based on the data from the first sensor and the second sensor; The first parameter is compared with a first parameter threshold, and the second parameter is compared with a second parameter threshold; When the first parameter is less than or equal to the first parameter threshold and the second parameter is less than or equal to the second parameter threshold, the control module determines that the two sensors are in a normal state; otherwise, it determines that the two sensors are abnormal and controls the power tool to stop running. When the control module determines that the two sensors are in a normal state, it calculates the difference between the data of the two sensors. If the difference is less than a difference threshold, the control module controls the power tool to continue running and repeats the above judgment. If the difference is greater than or equal to the difference threshold, the control module controls the power tool to stop running. The difference threshold is a function of the data of the first sensor and the data of the second sensor.

9. The power tool control method according to claim 8, characterized in that: The control module collects the temperature from the first sensor. , ... and the temperature of the second sensor , ... Where N is the number of data points collected by the control module.

10. The power tool control method according to claim 8, characterized in that: The first parameter threshold, the second parameter threshold, and the difference threshold are all pre-stored in the control module.

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