TWI403060B - Motor speed control device for electric lawn mower - Google Patents

Description

Motor speed control device for electric lawn mower

The invention provides an idling state in which the motor is maintained at a low rotation speed by means of pulse width modulation, and the appropriate working speed of the motor is regulated, so that the motor rotation speed can be maintained within the allowable working range for a long time, thereby greatly improving the battery use. Motor speed control device for efficient electric lawn mowers.

According to the traditional lawn mowers, most of them use mechanical engines as the power source. However, when such engine type lawn mowers are used, the vibration, noise and air pollution generated by them are extremely easy to cause the operator's body. Many bad effects.

In order to solve the shortcomings of the traditional engine mower, the manufacturer developed an electric lawn mower with an electric motor as the power source; please refer to the electric cutting machine used in the series as shown in Figures 1 and 2. The lawn mower 10 includes an operating rod 11 having a battery 12 at one end, a motor 13 for driving the cutter 14 at the other end, and a handle 15 on the operating rod 11, and the handle 15 is provided thereon. A power switch 16 electrically connected to the battery 12 and the motor 13 is disposed, and the power switch 16 is used to control the starter motor 13 to drive the cutter 14 to perform a mowing operation; however, the electric lawn mower 10 can solve the engine type. The problems of vibration, noise and air pollution of the lawn mower still have the following drawbacks in use:

1. The electric lawn mower 10 fails to control the voltage of the battery 12 to stabilize the appropriate output, and cannot adjust the rotation speed of the control motor 13 for the type of turf to be trimmed or cut. When the storage capacity of the battery 12 is high, That is, the motor 13 is driven at a high voltage for high-speed rotation. If the turf to be trimmed or cut does not need such a high rotational speed, the battery 12 is wasted power, which not only shortens the life of the electric lawn mower 10, but also shortens the life time of the electric lawn mower 10. The use efficiency of the battery 12 is greatly reduced.

2. The battery 12 of the electric lawn mower 10 is rapidly consumed as the usage time increases. When the storage capacity of the battery 12 becomes low, the motor 13 is rotated at a lower voltage, so that the rotation speed of the motor 13 is changed. Slowly, at this time, if the driving motor 13 is continuously rotated, the battery 12 is easily over-discharged, thereby greatly reducing the service life of the battery 12.

3. After the power switch 16 is turned on, the motor 13 is driven to rotate from the stop state by the voltage of the battery 12, and the rotational speed is instantaneously increased enough to perform mowing, however, the action of increasing the rotational speed at this moment is increased. The output voltage of the battery 12 will change almost in a class-like manner, and such a drastic voltage change not only quickly consumes the power of the battery 12, but also easily damages the battery 12, and greatly reduces the service life of the battery 12. .

4. When the electric lawn mower 10 is used, if the cutter 14 is entangled in the grass and the motor 13 cannot be smoothly operated or stopped, the current input to the motor 13 will continuously increase in order to overcome this obstacle. In order to increase the output torque of the motor 13, at this time, if the power switch 16 is not turned off, the motor 13 and the power switch 16 are easily burned and damaged, which causes considerable trouble in use.

In view of this, the inventor has been engaged in research and development and production experience of related industries for many years, and has conducted in-depth research on the problems currently faced. After long-term efforts and trials, he finally developed a control device for electric lawn mowers. In order to greatly improve the shortcomings of the practice, this is the design purpose of the invention.

The main object of the present invention is to provide a motor speed control device for an electric lawn mower, which is mainly connected with a power switch, an undervoltage protection unit, an overcurrent protection unit, and a pulse between the battery pack and the motor of the electric lawn mower. The wave width adjusting unit and the driving unit, the undervoltage protection unit and the overcurrent protection unit can respectively compare the output voltage level and the current level of the battery pack, and transmit the signal to the settable adjustable output pulse wave high level and the low level a pulse width adjusting unit of a bit duration, wherein the pulse width adjusting unit controls the driving unit to output a pulse wave voltage to drive the motor to rotate according to the received normal signal; thereby, the motor speed is adjusted by using a pulse width modulation method. For the type of turf, the appropriate working speed of the motor can be adjusted, so that the motor speed can be maintained within the allowable working range for a long time, thereby achieving the practical purpose of greatly improving the battery use efficiency.

Another object of the present invention is to provide a motor speed control device for an electric lawn mower, wherein the pulse width adjusting unit can set a duration to a minimum value of the output pulse wave high level to control the driving unit to output a meridian. The fixed average voltage after the wave width is modulated, and the driving motor is maintained at an idle state of low rotation speed, and when the control motor instantaneously increases the rotation speed, the output voltage of the battery pack can be prevented from being drastically changed, thereby achieving a substantial increase in battery life. And the practical purpose of using the battery life.

Another object of the present invention is to provide a motor speed control device for an electric lawn mower, wherein the overcurrent protection unit can compare the output current level of the battery pack and transmit the signal to the pulse width adjusting unit. The wave width adjusting unit drives the motor to output the pulse wave voltage to drive the motor to rotate according to the received normal signal, and when the output current level of the battery pack is abnormal, the pulse width adjusting unit is reset, and the output control is stopped. The signal triggered by the driving unit stops the rotation of the motor, and prevents each component from being burned and damaged due to the overload of the output current of the battery pack, thereby achieving the practical purpose of overload protection.

A second object of the present invention is to provide a motor speed control device for an electric lawn mower, wherein the undervoltage protection unit can compare the output voltage level of the battery pack and transmit the signal to the pulse width adjusting unit. The wave width adjusting unit drives the motor to output the pulse wave voltage to drive the motor to rotate according to the received normal signal, and the pulse width adjusting unit is reset when the output voltage level and the current level of the battery pack are abnormal. The output of the control drive unit trigger signal is stopped, so that the motor stops rotating to prevent the battery pack from being over-discharged, and thus achieve the practical purpose of prolonging the battery life.

In order to make the present invention more fully understood by the reviewing committee, the preferred embodiment and the drawing will be described as follows: Please refer to Figures 3 and 4, the motor speed control device of the electric lawn mower of the present invention, The electric lawn mower 20 is provided with a motor 31 driven by the battery pack 30 on a rod body 21, and a control device 40 is electrically connected between the battery pack 30 and the motor 31, and is suitable for the rod body 21. A control seat 22 is disposed at the position, and a cutter 50 is disposed at the front end, wherein the motor 31 is a DC motor, and the battery pack 30 is composed of a plurality of lithium iron phosphate batteries; and the control device 40 is electrically The battery pack 30 is connected between the battery pack 30 and the motor 31, and the battery pack 30 is used as a power source for the load of the motor 31 and the control device 40, and the current of the output battery pack 30 is controlled by the control device 40 to drive the motor 31 to rotate. The device 40 includes a power switch 41, an overload protection switch 42, a voltage stabilization unit 43, an undervoltage protection unit 44, an overcurrent protection unit 45, a pulse width adjustment (PWM) unit 46, a drive unit 47, and a display unit 48. Power switch 41 is installed in the control 22, and electrically connected to the output end of the battery pack 30 for controlling the power supply to open and close the load; the overload protection switch 42 is connected in series between the battery pack 30 and the motor 31, the overload protection switch 42 can be a A fuseless switch protector having non-destructive characteristics, in order to perform a power-off abnormality, that is, performing a power-off operation of the contact trip, the overload protection switch 42 is provided with a cover mounted on the control seat 22. Returning to button 421 for reversing the abnormal condition, the overload protection switch 42 can be re-opened; the voltage stabilizing unit 43 is connected to the output end of the overload protection switch 42 to input the voltage (Vbb) of the battery pack 30, and can output a stable voltage (Vcc); the undervoltage protection unit 44 generates a reference voltage value (Vref) in a divided manner by using a stable voltage (Vcc) output from the voltage stabilization unit 43, and senses an output voltage (Vbb) of the battery pack 30. Sensing the voltage value (Vbb1), and comparing the voltage level with the reference voltage value (Vref) and the sensing voltage value (Vbb1), when the sensing voltage value (Vbb1) is higher than the reference voltage value (Vref) , that is, the signal that controls the output voltage high level, when the voltage value is sensed (Vb When b1) is lower than the reference voltage value (Vref), the signal of the output voltage low level is controlled; the overcurrent protection unit 45 senses the sensed current value (Im) outputted by the battery pack 30, and The current value (Im) is compared with a preset reference current value (Iref), and when the sense current value (Im) is higher than the reference current value (Iref), the signal for controlling the output current high level is controlled. When the sensing current value (Vbb1) is lower than the reference current value (Iref), the signal of the output current low level is controlled; the pulse width adjusting unit 46 is connected to the first device provided on the control seat 22. The adjusting component 461 and the second adjusting component 462 are the variable resistors, and the resistance values of the first adjusting component 461 and the second adjusting component 462 are changed by adjustment to respectively The duration (toff and ton) of adjusting the output pulse voltage high level and the low level is set, and the voltage high level signal output by the under voltage protection unit 44 and the current low level signal output by the over current protection unit 45 are received. And outputting a pulse width modulation signal according to the received signal; The unit 47 is a power crystal, the power input end is connected to the output end of the overload protection switch 42, the output end is connected to the motor 31, and the other signal input end receives the pulse width modulation signal output by the pulse width adjusting unit 46. In order to control the driving unit 47 to trigger the time (toff and ton), the pulse width modulation mode is used to control the driving unit 47 to output the pulse wave driving motor 31 to rotate, thereby controlling the motor 31 to maintain the idle state at a low speed. The display unit 48 is mounted on the control base 22, and is provided with a first display element 481 capable of displaying a normal voltage, and a second display element 482 having a low voltage. The third display element 483 of the current and the fourth display element 484 of the idle state can receive the voltage level signal output by the undervoltage protection unit 44 and the current level signal output by the overcurrent protection unit 45, and according to the received signal. The first, second, third, and fourth display elements 481, 482, 483, and 484 are respectively displayed for display so that the user can grasp the operation of the battery pack 30 and the motor 31 at any time. State.

Referring to Figures 3 and 5, before the electric lawn mower of the present invention is used, the pulse width adjusting unit 46 of the control device 40 can be used to set the rotational speed of the motor 31 in the idle state, which is the pulse width. The first adjusting component 451 (toff) of the adjusting unit 46 is fixed, and the second adjusting component 462 (ton) is set to a minimum value, and the driving unit 47 outputs a fixed average voltage after the pulse width modulation, and drives the motor. 31 is maintained at an idle state of low speed for insufficient mowing operation, and the display unit 48 receives the signal of the idle state, and triggers the display element 481 and the display element 484 according to the received signal to perform normal display voltage and idle speed. In the state of operation, if the control motor 31 instantaneously increases the rotational speed, the output voltage of the battery pack 30 can be prevented from being drastically changed, thereby greatly improving the battery life and the use of the battery life.

Continuing to refer to FIGS. 3 and 5, when performing the mowing operation, the operator can adjust the appropriate working speed of the motor 31 by using the pulse width adjusting unit 46 of the control device 40 for various types of turf. In the case that the first adjusting component 461 (toff) remains unchanged, the duty cycle of the output pulse wave of the pulse width adjusting unit 46 can be changed by adjusting the length of time of the second adjusting component 462 (ton). And changing the actual average voltage of the supply motor 31, and by adjusting the actual average voltage, the appropriate operating speed of the motor 31 can be adjusted, and the pulse-wave width modulation is used to control the output of the pulse voltage by the driving unit 47. The driving motor 31 rotates at an appropriate working speed for mowing operation, and the pulse wave width modulation mode is used to control the output pulse wave voltage to drive the motor 31 to rotate, which not only prolongs the use of the battery life, but also allows the motor 31 to rotate. It can be kept within the allowable working range for a long time, thereby achieving the practical purpose of greatly improving the battery use efficiency; and during the normal operation, the control device 40 is underpowered. The protection unit 44 performs the sensing voltage value (Vbb1) outputted by the sensing battery pack 30 and compares it with the reference voltage value (Vref), and the overcurrent protection unit 45 simultaneously senses the sensing current output by the battery pack 30. The value (Im) is compared with the reference current value (Iref). When the sense voltage value (Vbb1) of the undervoltage protection unit 44 is higher than the reference voltage value (Vref), that is, the output voltage high level signal to the pulse wave When the width adjustment unit 46 and the sense current value (Im) of the overcurrent protection unit 45 are lower than the reference current value (Iref), that is, the output current low level signal to the pulse width adjustment unit 46, the pulse width adjustment The unit 46 continuously outputs the pulse width modulation signal according to the received signal to control the driving unit 47 to output the pulse wave voltage driving motor 31 for rotation for the mowing operation.

Referring to Figures 3 and 6, the present invention is in the process of mowing, and if the cutter 50 of the electric lawn mower 20 is stopped by the grass, the motor 31 will not rotate smoothly. 31 In order to overcome this obstacle, the input current will be increased all the time, and the output torque will be increased to overcome the obstacle. However, if this condition is not eliminated as soon as possible, the load current will be abnormally increased, and the current overload condition will occur. The overcurrent protection unit 45 of the control device 40 can sense the abnormality that the sense current value (Im) outputted by the battery pack 30 is higher than the reference current value (Iref). At this time, the pulse width adjustment unit 46 will The display unit 48 also stops the output pulse wave voltage modulation signal, and the driving unit 47 also stops the output pulse wave voltage driving motor 31 to rotate to achieve the purpose of overload protection, and the display unit 48 receives the overcurrent protection unit 45 output. The current is high level signal, and the display element 483 is triggered to display the current overload condition according to the received signal, and the user can perform the elimination according to the condition displayed by the display unit 48. Please refer to the figures 3 and 7, and if a current overload condition occurs and the overcurrent protection unit 45 does not operate, the overload protection switch 42 can also be used to perform the power-off operation of the contact trip, and the abnormality occurs. After the situation is removed, the override button 421 of the overload protection switch 42 can be re-opened, and the electric lawn mower 20 can be restarted, and the same purpose can be achieved for overload protection.

Referring to Figures 3 and 8, the present invention is in the process of mowing, the power of the battery pack 30 is gradually consumed, and the sense voltage value (Vbbl) of the undervoltage protection unit 44 is lower than the reference voltage value ( When Vref), the undervoltage protection unit 44 outputs a signal with a low voltage level. At this time, the pulse width adjusting unit 46 will be reset in time to stop outputting the pulse width modulation signal, and the driving unit 47 is also The output pulse wave voltage driving motor 31 is stopped to prevent the battery pack 30 from being over-discharged, and the display unit 48 receives the voltage low level signal output by the undervoltage protection unit 44, and triggers the display element 482 to display according to the received signal. In the case of insufficient voltage, the user can remove the battery pack 30 according to the condition displayed by the display unit 48 and perform charging, thereby achieving the purpose of prolonging the service life of the battery pack 30.

In summary, the present invention has practical and progressive nature, but it has not been disclosed that the same products and publications are disclosed, so that the requirements for invention patent applications are allowed, and the application is filed according to law.

Part of the formula:

10. . . Electric lawn mower

11. . . Joystick

12. . . battery

13. . . motor

14. . . Tool

15. . . handle

16. . . switch

Part of the invention:

20. . . Electric lawn mower

twenty one. . . Rod body

twenty two. . . Control seat

30. . . Battery

31. . . motor

40. . . Control device

41. . . switch

42. . . Overload protection switch

421. . . Override button

43. . . Voltage regulator unit

44. . . Undervoltage protection unit

45. . . Overcurrent protection unit

46. . . Pulse width adjustment unit

461. . . First adjustment component

462. . . Second adjustment component

47. . . Drive unit

48. . . Display unit

481. . . First display unit

482. . . Second display unit

483. . . Third display unit

484. . . Fourth display unit

50. . . Tool

Figure 1: Schematic diagram of the appearance of a conventional electric lawn mower.

Figure 2: Schematic diagram of the structure of the conventional electric lawn mower control.

Figure 3: Schematic representation of the use of the invention.

Figure 4: Schematic diagram of the structure of the control device of the present invention.

Fig. 5 is a schematic view showing the structure of the present invention in a normal use state.

Figure 6: Schematic diagram of the architecture of the present invention in the event of a current overload (1).

Figure 7: Schematic diagram of the architecture of the present invention in the event of a current overload (2).

Figure 8 is a schematic diagram of the architecture of the present invention in the event of a voltage deficiency.

20. . . Electric lawn mower

twenty one. . . Rod body

twenty two. . . Control seat

30. . . Battery

31. . . motor

40. . . Control device

41. . . switch

421. . . Override button

461. . . First adjustment component

462. . . Second adjustment component

48. . . Display unit

50. . . Tool

Claims (10)

A motor speed control device for an electric lawn mower, which is provided with a motor driven by a battery pack on a rod body, and a control device is arranged between the battery pack and the motor to control the rotation of the current drive motor of the output battery pack, The control device comprises: a power switch: electrically connected to the output end of the battery pack for controlling the power supply of the load to be closed and closed; the voltage stabilizing unit is electrically connected to the output end of the battery pack for stable output Voltage; undervoltage protection unit: the sensing voltage value of the battery pack output voltage is sensed, and the sensing voltage value is compared with the preset reference voltage value to compare the voltage level, and the voltage level signal is output; the overcurrent The protection unit is configured to sense the sensing current value of the output current of the battery pack, and compare the current value with the preset reference current value to compare the current level, and output the signal of the current level; the pulse width adjusting unit: The first adjusting component and the second adjusting component are respectively connected to respectively set the duration of adjusting the high level and the low level of the output pulse voltage, and can receive the output of the undervoltage protection unit The voltage level signal and the current level signal output by the overcurrent protection unit output a pulse width modulation signal according to the received signal; the driving unit has a power input end connected to the overload protection switch, and an output end connected to the motor, and another The signal input end receives the pulse width modulation signal outputted by the pulse width adjustment unit to control the length of the trigger time, and controls the output pulse voltage to drive the motor rotation in the pulse width modulation mode. The motor speed control device for an electric lawn mower according to claim 1, wherein the rod system is provided with a control seat at an appropriate position, and a cutter is installed at the front end. The motor speed control device of the electric lawn mower according to claim 1 of the patent application scope further comprises an overload protection switch connected in series between the battery pack and the motor. The motor speed control device of the electric lawn mower according to claim 3, wherein the overload protection open relationship is a non-destructive fuseless switch protector for abnormal conditions in which current overload occurs. That is, the power-off action of the contact trip is performed, and an override button is provided for re-opening the overload protection switch. The motor speed control device for the electric lawn mower according to the first aspect of the invention, wherein the first adjusting element and the second adjusting element of the pulse width adjusting unit are variable resistors. The motor speed control device of the electric lawn mower according to claim 1 further includes a display unit for receiving the voltage level signal output by the undervoltage protection unit and the current level signal output by the overcurrent protection unit. And according to the received signal, the operating state of the electric lawn mower is displayed. The motor speed control device for an electric lawn mower according to the sixth aspect of the invention, wherein the display unit is provided with a first display element capable of displaying a normal voltage, a second display element having a low voltage, and an overcurrent a third display element and a fourth display element in an idle state. The motor speed control device for an electric lawn mower according to claim 1, wherein the undervoltage protection unit generates a reference voltage value in a partial pressure manner by using a stable voltage output from the voltage stabilization unit. The motor speed control device of the electric lawn mower according to the first aspect of the invention, wherein the undervoltage protection unit is a signal for controlling the output voltage high level when the sensing voltage value is higher than the reference voltage value, When the sensed voltage value is lower than the reference voltage value, the signal of the output voltage low level is controlled. The motor speed control device for the electric lawn mower according to claim 1, wherein the overcurrent protection unit is configured to control the output current high level signal when the sense current value is higher than the reference current value. When the sense current value is lower than the reference current value, the signal of the output current low level is controlled.