Overload protection method for controlling electric tool machine by using current sum value

Abstract

The invention discloses an overload protection method for controlling an electric machine tool by using a current sum value. The method comprises the following steps: setting a constant value D1 in a control system; the current value of the motor during operation is detected, the current value is a continuous wave-shaped current waveform, and the current values of the single first working process and the single second working process are combined into a waveform unit in the current waveform; adding the current wave peak values of the second working process in the two adjacent waveform units in the unit time to obtain a sum value D2, and comparing the sum value D2 with the fixed value D1; when the sum value D2 is larger than the fixed value D1, the control system controls the motor to stop; and when the sum value D2 is smaller than or equal to the fixed value D1, the electric machine tool continues to run, the program for detecting the current value of the motor and comparing the current value is executed again, the problem that the machine is damaged due to the fact that the machine still runs when the electric machine tool is overloaded is solved through the method, and the overload protection effect on the grease gun which is not detected by the pressure sensor can be achieved.

Description

Technical Field

[0001] The present invention relates to an electric tool, and in particular to an overload protection method for controlling the electric tool by using a current and a value. Background Art

[0002] When the electric tool is working under load, the motor used to provide power inside will reduce its speed due to excessive load, thereby increasing the current. When the current of the motor exceeds a certain value and lasts for a certain period of time, the motor will burn out. The conventional overcurrent protection mode generally constrains the maximum output of the motor according to the specified current value and delay time set in advance, that is, the time working under the maximum current + the maximum current. The protection range is set by these two factors. When the current of the motor reaches the maximum current and works under this current for more than the set time, the circuit is closed, thereby achieving the function of protecting the circuit and the motor. This method has better consistency in the conventional electric tools and continuously running motors, mainly because the current of the motor increases or decreases linearly during the operation of the conventional electric tools, which is easy to control and detect. However, there are special types of existing electric tools. This type of electric tool has two working processes, which makes the current present a continuous wavy current waveform, such as a grease gun. The grease gun realizes the oil suction process of drawing the grease in the oil storage cylinder into the oil pipe through the reciprocating motion of the internal plunger, and the oil pressing process of pressing the grease drawn into the oil pipe out of the grease machine.

[0003] For example, the lithium battery grease gun disclosed in patent CN216431198U includes a grease gun housing and a grease gun oil storage cylinder. The grease gun oil storage cylinder is located at the top of the grease gun housing. A grease pump body is arranged on the left side inside the grease gun housing. The grease pump body is connected to the grease storage cylinder. The grease pump body includes a cylinder sleeve made of high-carbon alloy steel and a plunger made of high-carbon alloy steel. The cylinder sleeve is embedded in the upper channel of the grease pump body. The head of the plunger penetrates into the cylinder sleeve and the lower part penetrates into the lower channel of the grease pump body. A gear sleeve is arranged on the top of the cylinder sleeve. A plug is arranged on the top of the gear sleeve. The motor provides power to drive the plunger to reciprocate back and forth in the channel to press the grease in the oil storage cylinder outward. The plunger moves in the channel During the compound movement process, the pressure in the channel (i.e., the output pressure) will change accordingly, thereby affecting the current change of the grease gun. When the plunger moves backward, the volume of the channel content expands, the pressure in the channel decreases, and negative pressure is generated. The butter in the butter storage cylinder is pressed into the channel, and the current in this process decreases. When the plunger moves forward, the volume of the channel decreases, the pressure in the channel increases, and positive pressure is generated. The butter in the plunger channel is squeezed out from the outlet, and the current in this process increases. A continuous waveform current value is formed in the continuous oil suction and oil compression process. The current change in a single oil suction and oil compression process is a cycle, and one cycle has a current peak value and a current trough value.

[0004] When the output pressure in the grease gun channel exceeds the maximum protection pressure, the grease gun will be damaged due to current overload. However, since the current value of the grease gun changes in a wave shape, this type of current form cannot effectively protect the grease gun if the two factors of the maximum current condition + the working time under the maximum current condition are used for protection. Now an overload protection method is needed to protect the grease gun. Summary of the invention

[0005] Based on the above-mentioned problem that the existing grease gun has no overload protection, the present invention provides an overload protection method for an electric tool machine by controlling the current and value.

[0006] The technical solution adopted by the present invention to solve the above technical problems is: a method for controlling overload protection of an electric tool machine by using current and value, the method comprising:

[0007] A constant value D1 for comparison is set in the control system;

[0008] Detecting the current value of the motor of the electric tool machine when it is in operation, the current value forms a continuous wavy current waveform due to the electric tool machine continuously and alternately changing in the first working process and the second working process, and the motor current values ​​of the single first working process and the second working process are combined into a waveform unit in the current waveform, and one waveform unit has an adjacent current peak value and a current valley value;

[0009] The current wave peak value of the second working process in a waveform unit within a unit time is added to the current wave peak value of the second working process in another adjacent waveform unit to obtain a sum value D2, and the sum value D2 is compared with the fixed value D1;

[0010] When the sum value D2> the fixed value D1, the control system controls the motor to stop;

[0011] When the sum D2 ≤ the constant D1, the electric tool continues to run, re-executes the aforementioned procedure of detecting the motor current value, and compares the sum D2 of the current wave peak values ​​of the second working process in two adjacent waveform units within a unit time with the set constant D1.

[0012] A further preferred technical solution of the present invention is: the current signal output by the motor during operation is detected by a detection element to obtain the current value of the motor, and the detection element is electrically connected to the control system.

[0013] A further preferred technical solution of the present invention is: the detection element is a current sensor.

[0014] A further preferred technical solution of the present invention is that the motor current value detected per unit time includes at least two waveform units.

[0015] Compared with the prior art, the advantage of the present invention is that the maximum protection pressure of the grease gun is closely related to the sum of the current wave peak values ​​of two adjacent waveform units when the motor is working, that is, the maximum protection pressure corresponds to a fixed maximum sum value, and the maximum sum value is set in the control system as a constant value D1 for comparison. By detecting the current value of the motor in the continuously running grease gun, the current wave peak values ​​of the oil pressure process in two adjacent waveform units within a unit time are added to obtain the sum value D2, and the sum value D2 is compared with the constant value D1. When the sum value D2> the constant value D1, it means that the pressure exceeds the maximum protection pressure at this time, and the control system controls the motor to stop. When the sum value D2≤the constant value D1, it means that the pressure does not exceed the maximum protection pressure at this time, and the machine runs normally. The control system re-executes the aforementioned program of detecting the current value of the motor and comparing the sum value D2 of the current wave peak values ​​of the oil pressure process in two adjacent waveform units within a unit time with the set constant value D1, so as to prevent the grease machine from being damaged when the output pressure exceeds the maximum protection pressure while the machine is still running, and can play an overload protection effect on the grease gun without pressure sensor detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention will be further described in detail below in conjunction with the accompanying drawings and preferred embodiments, but those skilled in the art will appreciate that these drawings are drawn only for the purpose of explaining the preferred embodiments and therefore should not be used as a limitation on the scope of the present invention. In addition, unless otherwise specified, the drawings are only schematically representing the composition or structure of the described objects and may contain exaggerated displays, and the drawings are not necessarily drawn to scale.

[0017] Figure 1 is a flow chart of the overload protection method;

[0018] Figure 2 This is the current waveform diagram when the electric tool machine is working;

[0019] Figure 3 Schematic diagram of waveform unit.

[0020] In the figure: 1. Current peak value; 2. Current valley value. DETAILED DESCRIPTION

[0021] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It will be appreciated by those skilled in the art that these descriptions are only illustrative and exemplary and should not be construed as limiting the scope of protection of the present invention.

[0022] It should be noted that like reference numerals denote similar items in the following drawings, and thus, once an item is defined in one drawing, it may not be further defined or explained in subsequent drawings.

[0023] Figure 1-Figure 3 As shown, a method for overload protection of an electric tool machine using a current sum value is described. In this embodiment, the electric tool machine is represented by a grease gun. This overload protection method is based on the principle that the maximum protection pressure (maximum output pressure) of the grease gun is closely related to the sum of the current peak values ​​1 of two adjacent waveform units when the motor is working. It means that the maximum protection pressure (maximum output pressure) of the grease gun has a sum of the current peak values ​​1 of two adjacent waveform units corresponding to it. The sum is set to a reference sum value, and the sum is a constant value. When it is detected that the sum of the current peak values ​​1 of two adjacent waveform units is less than or equal to the reference sum value, it means that the output pressure of the grease gun does not exceed the maximum protection pressure (maximum output pressure) of the grease gun at this time. Pressure), the grease gun is in normal working condition. When it is detected that the sum of the current wave peak value 1 of two adjacent waveform units is greater than the reference sum value, it means that the output pressure of the grease gun has exceeded the maximum protection pressure (maximum output pressure) of the grease gun. The grease gun is in overload working condition and needs to be shut down for protection. For example, the maximum protection pressure (maximum output pressure) of the grease gun is one gigapascal when it is working, and the corresponding reference sum value is 5A. When it is detected that the sum of the current wave peak value 1 of two adjacent waveform units is less than or equal to 5A, it means that the output pressure of the grease gun does not exceed one gigapascal at this time. When it is detected that the sum of the current wave peak value 1 of two adjacent waveform units is greater than 5A, it means that the output pressure of the grease gun has exceeded one gigapascal at this time. The specific contents are as follows:

[0024] The sum value corresponding to the above-mentioned maximum protection pressure (maximum output pressure) of the grease gun is set in the control system as a constant value D1 for comparison.

[0025] Figure 2 , Figure 3 As shown, the current value of the motor of the grease gun is detected when it is running. The current value forms a continuous wavy current waveform due to the continuous alternation of the grease gun in the first working process and the second working process, and the motor current values ​​of the single first working process and the second working process are combined into a waveform unit in the current waveform. A waveform unit has an adjacent current peak value 1 and a current valley value 2.

[0026] The above-mentioned first working process and second working process are the oil suction process in which the plunger in the grease gun reciprocates back and forth due to the operation of the motor to suck the grease in the oil storage cylinder, and the oil pressing process in which the sucked grease is pressed out of the grease gun. Due to the oil suction and oil pressing operations, the detected current value presents a continuous wavy current waveform, and the plunger reciprocates once to complete an oil suction process and an oil pressing process. The current values ​​of an oil suction process and an oil pressing process are combined into a waveform unit in the above-mentioned current waveform, and a waveform unit has an adjacent current peak value 1 and a current trough value 2.

[0027] For the detection of the current when the motor is running, this embodiment detects the current signal output by the motor when it is running through the detection element to obtain the current value of the motor. The detection element is electrically connected to the control system, and the detection element feeds back information to the control system during detection. Preferably, the control system is a control circuit board.

[0028] Preferably, the detection element is a current sensor, for example, a current sensor of Nanjing Xiangshang brand and model DL-CT03C1.0.

[0029] The current peak value 1 of the oil pressure process in one waveform unit within a unit time is added to the current peak value 1 of the oil pressure process in another adjacent waveform unit to obtain the sum value D2, and the sum value D2 is compared with the above-mentioned constant D1.

[0030] When the sum D2>the fixed value D1, the control system controls the motor to stop.

[0031] When the sum D2 ≤ the fixed value D1, the grease gun continues to run, re-executes the aforementioned detection of the motor current value, and compares the sum D2 of the current peak value 1 of the oil pressure process in two adjacent waveform units within a unit time with the set fixed value D1.

[0032] The overcurrent protection method can prevent the grease machine from being damaged by the machine when the output pressure exceeds the maximum protection pressure (maximum output pressure) and can provide overload protection for grease guns without pressure sensor detection.

[0033] The motor current value detected within the above unit time includes at least two waveform units. For example, if the unit time is set to 2S, and the working plunger in the grease gun reciprocates at least twice within 2S, then the motor current value in this time period forms at least two continuous waveform units.

[0034] Figure 1 As shown, the above method comprises the following steps:

[0035] S1, set a constant value D1 for comparison in the control system;

[0036] S2, detecting a current value of a motor of the electric tool machine when it is in operation, the current value continuously and alternately changing in a first working process and a second working process of the electric tool machine to form a continuous wavy current waveform, and the motor current values ​​of a single first working process and a single second working process are combined into a waveform unit in the current waveform, and a waveform unit has an adjacent current peak value 1 and a current valley value 2;

[0037] S3, adding the current wave peak value 1 of the second working process in a waveform unit within a unit time to the current wave peak value 1 of the second working process in another adjacent waveform unit to obtain a sum value D2;

[0038] S4, compare the sum D2 with the fixed value D1;

[0039] S5, judging whether the sum value D2 is less than or equal to the fixed value D1, if not, the control system controls the motor to stop, if so, the electric tool operates normally, and step S2 is executed again.

[0040] The above method is not only applicable to grease guns, but other electric tools with the same working mode as grease guns are also applicable to the overload protection method for protection.

[0041] The above is an introduction to the overload protection method of the electric tool machine using current and value control provided by the present invention. This article uses specific examples to illustrate the principle and implementation of the present invention. The description of the above embodiments is only used to help understand the present invention and its core ideas. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A method for controlling overload protection of an electric tool machine by using current and value, characterized in that: The method includes: A constant value D1 for comparison is set in the control system; Detecting the current value of the motor of the electric tool machine when it is in operation, the current value forms a continuous wavy current waveform due to the electric tool machine continuously and alternately changing in the first working process and the second working process, and the motor current values ​​of the single first working process and the second working process are combined into a waveform unit in the current waveform, and one waveform unit has an adjacent current peak value and a current valley value; The current wave peak value of the second working process in a waveform unit within a unit time is added to the current wave peak value of the second working process in another adjacent waveform unit to obtain a sum value D2, and the sum value D2 is compared with the fixed value D1; When the sum value D2> the fixed value D1, the control system controls the motor to stop; When the sum D2 ≤ the constant D1, the electric tool continues to run, re-executes the aforementioned procedure of detecting the motor current value, and compares the sum D2 of the current wave peak values ​​of the second working process in two adjacent waveform units within a unit time with the set constant D1.

2. The overload protection method for controlling an electric tool machine by using a current and a value according to claim 1, characterized in that: The current signal outputted by the motor during operation is detected by a detection element to obtain the current value of the motor, and the detection element is electrically connected to the control system.

3. The overload protection method for controlling an electric tool machine by using a current and a value according to claim 2, characterized in that: The detection element is a current sensor.

4. The overload protection method for controlling an electric tool machine by using a current and a value according to claim 1, characterized in that: The motor current value detected per unit time includes at least two waveform units.

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