JP2002354886A - Electric tool carried by hand - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effective protect a motor even in the condition that the motor may be over-heated by intermittently repeating a heavy load work. SOLUTION: This electric tool carried by hand comprises a driving motor 1 and a power transmitting part for transmitting motor output to an output shaft via a deceleration part. Moreover, this tool also includes a control means 5 for disconnecting the power transmitting part and motor when the detected value of heat generation of motor 1 is out of the constant range.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a hand-held power tool,
In particular, the present invention relates to a technique for protecting a motor against a motor lock.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication No. Hei 5-220677 discloses that a locked state of a motor is detected by using a rotation speed detecting means such as a tacho generator, and when a lock duration time exceeds a specified value, the motor is stopped. There is disclosed an apparatus in which power supply is stopped to protect a motor.

[0003]

When the motor is stopped by the protection of the motor, if the user resumes the operation again, the motor is reloaded and a new amount of heat is added to the amount of heat stored in the motor during the previous operation. Will be. Therefore, when the motor is used in such a manner that the motor protection operation repeatedly occurs, the motor may be damaged by heat.

[0004] In other words, the conventional motor can be protected under limited conditions such as when a specific current or more flows for a specific time or more, but the motor that is generated when a high load operation is intermittently repeated is performed. The protection function does not work for burnout.

[0005] As a means for detecting the load state of the motor, a pulse generator must be installed in addition to the motor. Further, in order to detect the heat storage state of the motor by using a pulse generator or a current, the temperature inside the motor is detected by a rotational speed or a current instead, and it is difficult to increase the accuracy of the detection.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and a purpose thereof is to effectively protect a motor even in a situation where a motor is overheated by intermittently repeating high-load work. It is an object of the present invention to provide a hand-held power tool.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a hand-held power tool having a driving motor and a power transmission unit for transmitting the output of the motor to an output shaft via a speed reducer. A first feature is that control means for detecting the amount and shutting off the power transmission unit and the motor when the detected value is out of a certain range is provided. Control that detects the amount of heat generated by the motor and reduces the current flowing through the motor when the detected value is out of a certain range in a hand-held power tool having a power transmission unit that transmits the power to an output shaft via a speed reducer. The provision of the means has a second feature.

At this time, it is preferable to provide a detecting means for detecting the amount of heat stored in the motor by integrating and calculating the amount of heat generated by the motor during the tool driving period and the amount of heat released during the tool stop period. It is preferable that the motor and the time detecting means are provided and the motor heat storage amount is calculated from the current value and the time value obtained by these detecting means.

The amount of heat generated by the motor is detected from the integration of the current and the time during the motor driving period, and the amount of heat radiation can be detected from the product of the heat dissipation coefficient and the time inherent in the device experimentally obtained. In such a case, the current detection may be performed during the motor driving period, and the time detection may be performed during the connection period to the power outlet. In the case of a battery power supply type, current detection is preferably performed during a motor drive period, and time detection is preferably performed during a period when a battery is loaded.

When the trigger switch for turning on / off the power supply to the motor is input, the power supply to the time detecting means is started, and when the signal for stopping the power supply to the time detection means is inputted, the power supply to the time detecting means is cut off. Alternatively, the power supply to the time detecting means may be interrupted when the integrated value of the motor heating value becomes equal to or less than the set value.

[0011] When the tool stop period elapses a predetermined time peculiar to the device determined experimentally, time detection is stopped,
When the power supply to the time detecting means is interrupted, the integrated value of the motor heat storage amount immediately before the power supply is interrupted is stored, and when the power supply is restarted, the stored integrated value is used as an initial value. In particular, the integrated value of the heat storage amount of the motor immediately before the interruption of the power supply, which is stored when the power supply to the time detection means is interrupted, is erased when a certain period of time inherently determined by the device has elapsed. Good to do.

The tool main body includes a tool activation main switch for turning on / off the power supply to the trigger switch and the power supply to the time detecting means, separately from a trigger switch for driving the tool by turning on / off the power supply to the motor. The main switch may be operated during the ON state.

The relationship between the heat value of the motor and the heat value of the resistor may be stored in advance in storage means, and the heat value of the resistor may be detected to determine the heat value of the motor based on the relationship.
In this case, the resistance is preferably provided on the exhaust side of the motor cooling fan.

It is needless to say that a temperature detecting means may be provided at the outlet of the cooling air of the motor.

It is also preferable to provide a notifying means for notifying when the power transmission between the motor and the tool output is interrupted.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to an example of an embodiment. In FIG. 2, the output of a motor 1 is output via a power transmission clutch 4 and a reduction gear 2 to an output shaft 3 having a chuck. Is transmitted to In the figure, 6 is a rectifier for rectifying the AC power, 14 is a trigger switch for turning on and off the motor 1, 5 is a controller for controlling the operation of the motor 1 and the power transmission clutch 4, and 5 is a current detector. 10, a time detection timer 11, a calculation unit 12, a trigger switch input detection unit 15, and the like.

In this electric power tool, when the detected value of the heat generation amount of the motor 1 is out of a certain range (when the motor 1 is overheated), the power transmission clutch 4 is disengaged to transmit the power to the output shaft 3. When the detected value of the calorific value of the motor 1 returns within a certain range, the control unit 5 returns the power transmission clutch 4 to the connected state. I have. The motor 1 may be stopped instead of idling, and a warning sound by a buzzer or a warning light emission by a light emitting diode may be performed to notify the user that the motor 1 has entered the motor protection state.

Although the power transmission clutch 4 is provided in the above example, as shown in FIG.
In this case, if overheating of the motor 1 is detected, the output current of the main body is reduced by limiting the output of the switching element 13 and the amount of heat generated by the motor 1 is detected. The above restriction may be released when the value returns to a certain range.

The detection of the amount of heat generated by the motor 1 is described here. When the trigger switch 14 is turned on,
The main body is energized, and during operation of the main body, the current detection unit 10 and the timer 11 for time detection add the heat storage amount in the calculation unit 12 according to the magnitude and duration of the load current of the main body. Subtracts the heat storage amount according to the pause duration.
This addition / subtraction is performed in accordance with the operation state to calculate the amount of heat stored in the motor. The amount of heat stored in the motor is used as the value of the amount of heat generated by the motor 1 and the power transmission clutch 4
And the operation of the switching element 13 is controlled.

FIG. 1 shows the above operation. In the figure, t1 indicates the time when the heat generation amount (heat storage amount) of the motor 1 is out of the predetermined range, and t2 in the figure indicates the time when the motor 1 cools and enters the predetermined range. The predetermined range has a hysteresis characteristic.

In the case where a commercial AC power supply is used as a power supply, the above calculation is continuously performed while the power supply is connected to the power supply, and the calculation data of the heat storage amount is reset when the power cord is disconnected from the outlet and disconnected from the power supply. It is like that.

In the case where a battery of a pack type is used as a power source, it is preferable that the calculation of the amount of stored heat is continuously performed during the period when the battery is loaded, and reset when the battery is removed.

As shown by a solid line in FIG. 6, the timer 11 for detecting time may be reset when a time T sufficient for the overheated motor 1 to sufficiently cool has elapsed.

FIG. 4 shows another example. This is provided with a calculation stop switch 16 for instructing the calculation unit 12 to stop the calculation operation of the heat storage amount. The calculation stop switch 16 outputs a calculation stop instruction signal when the heat storage amount falls within a certain value. . The calculation by the calculation unit 12 is restarted by turning on the trigger switch 14.
FIG. 5 shows an example in which a storage unit 17 for storing the calculation result of the heat storage amount is provided. The storage unit 17 is connected when the power supply is disconnected, that is, when the power cord is connected to the outlet. When the battery is removed or the battery is removed (t3 in FIG. 9), the stored heat amount data at that time is stored. The stored heat storage amount data is read out and set as an initial value when the power supply is next connected (t4 in FIG. 9).

FIG. 6 shows a memory provided with a discharge circuit unit 19 in addition to the storage unit 17.
Is turned on, the energization of the main body is detected, and during the operation of the main body, the heat storage amount is added by the calculation unit 12 in accordance with the magnitude and the duration of the load current of the main body. The heat storage amount is subtracted accordingly. Then, when the heat storage amount exceeds a certain value, it is determined that the detected value of the heat generation amount is out of the certain range, and the motor protection operation is performed. Thereafter, the heat storage amount is subtracted and the heat storage amount becomes within a certain value. When it becomes, it is judged that it has become within a certain range (sufficiently rained), and the motor protection operation is released.

The above operation is continuously performed during the period when the power supply is connected to the power supply, and the discharge circuit unit 19 is charged during the period.
Then, when the connection with the power supply is cut off, the data of the calorific value is stored in the storage unit 17. Then, when the connection with the power supply is cut off, the discharge in the discharge circuit unit 19 starts.
When the voltage of the discharge circuit unit 19 is lower than a certain value when the power supply unit is connected again, it is determined that the cooling circuit is sufficiently cooled due to a sufficient pause time, and the heat generation amount data stored in the storage unit 17 is determined. Is reset (see the heat generation amount data indicated by the broken line in FIG. 9). Discharge circuit unit 1 when reconnecting to power supply
If the voltage of No. 9 is equal to or more than a certain value, it is determined that the pause time is insufficient, and the heat storage amount data stored in the storage unit 17 is set as the initial value of the heat generation amount. The discharge characteristics of the discharge circuit section 19 are set so that the time Ta at which the temperature of the overheated motor 1 becomes sufficiently cooled is equal to the discharge time.

FIG. 8 shows an example in which an energizing switch 18 for turning on and off energization to the arithmetic unit 12 is provided.
Of the heat storage amount and the time count of the timer 11 are as follows:
This is performed only during a period in which the energizing switch 18 is turned on (see a dashed line in FIG. 9).

FIG. 10 shows that a resistor R for detecting the amount of heat generated by the motor is connected in series with the motor 1, the resistor R is arranged on the exhaust side of the built-in fan F of the motor 1, The sensor S is arranged near the resistor R.
The heating value of the winding of the motor 1 and the resistance R
Is determined in advance, and when the temperature of the resistor R exceeds a certain value, it is determined that the motor 1 has overheated and a motor protection operation is performed, and the temperature of the resistor R falls below a predetermined value. For example, the protection operation is canceled to enable the operation.

As shown in FIG. 11, the exhaust heat of the motor 1 may be detected by the temperature sensor S.

[0030]

As described above, according to the present invention, the control means for detecting the heat generation amount of the motor and shutting off the power transmission unit and the motor when the detected value is out of the predetermined range is provided. This is effective even in situations where the motor overheats due to intermittent repetition of high-load work because the motor can no longer work. Motor cooling can be carried out.

Further, even in the case where the motor is provided with a control means for detecting the amount of heat generated by the motor and reducing the current flowing to the motor when the detected value is out of a certain range, the motor is subjected to a high load operation intermittently and repeatedly. The motor can be prevented from being burned even when the motor is overheated.

At this time, there may be provided a detection means for detecting the heat storage amount of the motor by multiplying and calculating the heat generation amount of the motor during the tool driving period and the heat release amount during the tool stop period. With detection means,
It is assumed that the heat storage amount of the motor is calculated from the current value and the time value obtained by these detection means, and further, the heat generation amount of the motor is detected from the integration of the current and time during the motor driving period, and the heat release amount is experimentally calculated. If the product is detected from the product of the heat dissipation coefficient and the time that is unique to the device, the protection can be set arbitrarily according to the size of the load state and the application time, as well as the specific state such as the motor lock state. Since the amount of heat radiation and the amount of heat generated according to the length of the pause period during the intermittent operation can be taken into account, more accurate motor temperature protection and overload protection can be performed. .

In the case of using an AC power supply as a power supply,
The current detection shall be performed during the motor drive period, the time detection shall be performed during the connection period to the power outlet, and in the case of the battery power type, the current detection shall be performed during the motor drive period, and the time detection shall be performed during the period when the battery is loaded. In this case, the monitoring of the motor temperature is always performed while the power is connected.

When a trigger switch for turning on / off the power supply to the motor is inputted, the power supply to the time detecting means is started, and when a signal for stopping the power supply to the time detecting means is inputted, the power supply to the time detecting means is cut off. Then, unnecessary power consumption can be suppressed.

The power consumption can be suppressed even if the power supply to the time detecting means is cut off when the integrated value of the motor heat generation becomes equal to or less than the set value.

Even if the time detection is stopped when the tool stop period has passed a certain device-specific period determined experimentally,
Power consumption can be reduced.

When the power supply to the time detecting means is interrupted, the integrated value of the motor heat storage amount immediately before the power supply is interrupted is stored, and when the power supply is restarted, the stored integrated value is used as an initial value. If used, carelessly unplugging the power cord from the outlet during the work and reconnecting it to continue the work will not destroy the stored heat data, thus protecting the motor. It can be done reliably.

In addition, the integrated value of the heat storage amount of the motor immediately before the interruption of the power supply, which is stored when the power supply to the time detecting means is interrupted, is erased after a lapse of a predetermined time peculiar to the device experimentally obtained. By doing so, it is possible to prevent a situation in which the heat storage amount of the criterion becomes larger than the actual amount when the state in which the power supply is interrupted is sufficiently long.

The tool body includes a tool activation main switch for turning on and off the power supply to the trigger switch and the power supply to the time detecting means, separately from the trigger switch for driving the tool by turning on and off the power to the motor. The main switch may be operated during the ON state. Even with this, power consumption can be suppressed.

If the relationship between the heat value of the motor and the heat value of the resistor is stored in advance in the storage means, and the heat value of the resistor is detected and the heat value of the motor is determined from the above relationship, the heat resistant temperature is low. It is possible to easily perform the protection operation according to the thermal characteristics of the winding part. In particular, by setting the resistance on the exhaust side of the motor cooling fan, the detection accuracy can be increased.

Even if the temperature detection means is provided at the outlet of the cooling air of the motor, the temperature close to the winding can be detected.
It is possible to perform a protection operation according to the thermal characteristics of the winding part having a low heat-resistant temperature.

By providing a notifying means for notifying when the power transmission of the motor and the tool output is interrupted, it is possible to eliminate the possibility that the user may mistake the protection operation as a failure. Also, the user can easily recognize that the protection function has been released.

[Brief description of the drawings]

FIG. 1 is a time chart of an example of an embodiment of the present invention.

FIG. 2A is a block diagram of the above, and FIG. 2B is a block circuit diagram.

3A is a block diagram of another example, and FIG. 3B is a block circuit diagram.

FIG. 4 is a block circuit diagram of still another example.

FIG. 5 is a block circuit diagram of another example.

FIG. 6 is a time chart of another example.

FIG. 7 is a block circuit diagram of another example.

FIG. 8 is a block circuit diagram of another example.

FIG. 9 is a time chart of another example.

10A is a block diagram of a different example, and FIG. 10B is a block circuit diagram of the same.

FIG. 11A is a block diagram of still another example, and FIG. 11B is a block circuit diagram of the same.

[Explanation of symbols]

 Reference Signs List 1 motor 5 control unit 10 current detection unit 11 timer unit 12 calculation unit

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yosuke Ishida 1048 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Works, Ltd. (72) Inventor Hidekazu Yuasa 1048 Kadoma Kadoma, Kadoma City, Osaka Matsushita Electric Works F Terms (reference) 5H571 AA14 BB08 CC01 EE01 HA01 JJ18 KK06 LL14 LL22 MM02 MM06

Claims (17)

[Claims] 1. A hand-held power tool having a driving motor and a power transmission unit for transmitting the output of the motor to an output shaft via a speed reducer, wherein the heat value of the motor is detected and the detected value is constant. A hand-held power tool having control means for shutting off the power transmission unit and the motor when the power is out of the range. 2. A hand-held power tool having a driving motor and a power transmission unit for transmitting an output of the motor to an output shaft via a speed reducer, wherein the heat value of the motor is detected and the detected value is constant. A hand-held power tool having control means for reducing the current flowing through the motor when the power is out of the range. 3. A motor heating value during a tool driving period,
3. The hand-held power tool according to claim 1, further comprising a detection unit configured to detect a heat storage amount of the motor by performing an integration operation on a heat release amount during the tool stop period. 4. A device comprising a current detecting means and a time detecting means,
4. The hand-held power tool according to claim 3, wherein the motor heat storage amount is calculated from the current value and the time value obtained by the detection means. 5. The method according to claim 1, wherein the heat generation amount of the motor is detected from the integration of the current and the time during the motor driving period, and the heat radiation amount is detected from the product of the heat radiation coefficient inherent to the device experimentally obtained and the time. The hand-held power tool according to claim 3 or 4, wherein 6. An AC power supply as a power supply, wherein current detection is performed during a motor driving period and time detection is performed during a connection period to a power outlet. Hand-held power tool as described. 7. A battery-powered type, wherein current detection is performed during a motor driving period, and time detection is performed during a period in which a battery is loaded.
Or the hand-held power tool according to 5. 8. The power supply to the time detecting means is started when a trigger switch for turning on / off the power supply to the motor is inputted, and the power supply to the time detecting means is inputted when a signal for stopping the power supply to the time detecting means is inputted. 6. The hand-held power tool according to claim 3, wherein the power tool is shut off. 9. The hand-held power tool according to claim 3, wherein the power supply to the time detecting means is interrupted when the integrated value of the heat value of the motor becomes equal to or less than the set value. 10. The hand-held power tool according to claim 3, wherein the time detection is stopped when the tool stop period has elapsed after a predetermined time peculiar to the device determined experimentally. 11. When the power supply to the time detecting means is interrupted, an integrated value of the motor heat storage amount immediately before the power supply is interrupted is stored, and when the power supply is restarted, the stored integrated value is used as an initial value. 6. The hand-held power tool according to claim 3, wherein the power tool is used. 12. An integrated value of the motor heat storage amount immediately before the power supply interruption stored when the power supply to the time detecting means is interrupted is deleted when a predetermined time inherent to the device has been experimentally obtained. The hand-held power tool according to claim 11, characterized in that: 13. The tool main body includes a tool activation main switch for turning on / off the power supply to the trigger switch and the power supply to the time detecting means, separately from a trigger switch for driving the tool by turning on / off the power to the motor. 6. The hand-held power tool according to claim 3, wherein time detection is performed during a period when the main switch is turned on. 14. A relationship between the heat value of the motor and the heat value of the resistor is stored in advance in the storage means, and the heat value of the resistor is detected to determine the heat value of the motor from the relationship. The hand-held power tool according to claim 3 or 4, wherein: 15. The hand-held power tool according to claim 14, wherein a resistor is provided on an exhaust side of the motor cooling fan. 16. The hand-held power tool according to claim 1, wherein a temperature detecting means is provided at an outlet of the cooling air of the motor. 17. The hand-held power tool according to claim 1, further comprising a notifying means for notifying when the power transmission between the motor and the tool output is interrupted.