JP2015032388A - Dc power supply device and power tool system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a DC power supply device and a power tool system that enable a long-time continuous operation while suppressing deterioration, breakage and the like of a power supply component in the DC power supply device.SOLUTION: A DC power supply device comprises: output current detection means for detecting an output current; output current control means for controlling the output current; maximum allowable current value setting means for setting a maximum allowable current value; and temperature detection means for detecting a temperature of a power supply component. In a case where a value of the output current becomes larger than the maximum allowable current value, the output current control means stops the current output. The maximum allowable current value setting means changes the set maximum allowable current value depending on the temperature of the power supply component, detected by the temperature detection means.

Description

  The present invention relates to a DC power supply device, and more particularly to a DC power supply device suitable for use in a cordless power tool. The invention further relates to a power tool system.

  Conventionally, a DC power supply device has been widely used as a power source for various electric devices, and various solutions have been proposed for various problems that occur when an electric device is driven by the DC power supply device.

  For example, when the DC power supply device is used as the power source of the electric power tool, there is a problem that if the electric power tool is continuously used, the temperature of the motor built in the electric power tool and the components constituting the DC power supply device are increased. An increase in the temperature of the electric power tool contributes to a decrease in the life of the electric power tool itself, and an increase in the temperature of the DC power supply device causes deterioration or damage of parts.

  In order to solve the above-described problem, Patent Literature 1 includes a heating element having a temperature characteristic approximate to that of a motor of an electric tool, and a detection unit that measures the temperature of the heating element. Has disclosed a DC power supply device that stops power supply to the electric tool when the temperature exceeds a maximum allowable temperature.

JP 11-101836 A

  The above-described conventional DC power supply device is intended to protect the electric power tool, and the influence on the DC power supply device is not particularly considered. However, depending on the usage mode of the electric power tool, not only the electric power tool but also the DC power supply The device is also adversely affected. According to the invention described in Patent Document 1, the only factor for determining whether or not to stop the power supply to the power tool is the temperature. If the temperature is less than the allowable temperature, that is, the temperature that does not stop the power supply, The power tool can be configured to keep a large current flowing. Therefore, not only the electric power tool but also the DC power supply device may cause problems such as deterioration / breakage of parts and a decrease in life if the high temperature state close to the allowable temperature is maintained even if the temperature is lower than the allowable temperature. In addition, when a large current is passed through the power tool in such a high temperature state, the temperature tends to exceed the allowable temperature, and thus power supply is likely to be stopped. Therefore, there is a problem that the work cannot be continued.

  Therefore, an object of the present invention is to provide a DC power supply device that can perform continuous work for a long time while preventing deterioration and breakage of components of the DC power supply device.

  In order to solve the above-mentioned problems, the present invention provides an output current detection means for detecting an output current, an output current control means for controlling the output current, and a maximum allowable current value setting means for setting a maximum allowable current value. And a temperature detecting means for detecting the temperature of the power supply component, and the output current control means stops the current output when the value of the output current exceeds the maximum allowable current value. Thus, the maximum allowable current value setting means changes the set maximum allowable current value according to the temperature of the power supply component detected by the temperature detection means.

  According to such a configuration, the maximum allowable current value can be set to a different value depending on whether the temperature of the power supply component is high or low. For this reason, when the temperature of the power supply component is high, the maximum allowable current value is set low, so that the temperature rise of the component can be suppressed, and deterioration / breakage of the power supply component can be suppressed. In addition, by using the current within the range not exceeding the maximum allowable current value, it is possible to prevent the output from being stopped due to the high temperature of the component and to perform continuous work for a long time.

  In the above configuration, when the maximum allowable current value setting means sets the maximum allowable current value to the first maximum allowable current value and performs current output, the temperature detecting means performs the first maximum allowable current value. When a temperature higher than the first specified upper limit temperature corresponding to the current value is detected, the maximum allowable current value setting means sets the maximum allowable current value to a value lower than the first maximum allowable current value. It is preferable to change to a certain second maximum allowable current value.

  According to such a configuration, the maximum allowable current value is set lower as the temperature of the power supply component becomes higher, so that a large current cannot flow at a high temperature. For this reason, the temperature rise of components can be relieved and deterioration, damage, etc. of a power supply component can be suppressed more effectively.

  In addition, when the maximum allowable current value setting means sets the maximum allowable current value to the third maximum allowable current value and performs current output, the temperature detection means performs the third maximum allowable current value. Is detected, the maximum allowable current value setting means sets the maximum allowable current value to a value that is higher than the third maximum allowable current value. It is preferable to change to the maximum allowable current value.

  According to such a configuration, even when the maximum allowable current value has been changed to a low value due to the temperature rise of the power supply component, the maximum allowable current value is again increased when the temperature of the power supply component decreases. can do. For this reason, compared with the case where the work is performed in a state where the maximum allowable current value is once set to be low, the output stop due to the high temperature of the parts is prevented, and continuous work for a long time is possible, and workability is improved.

  Further, it is preferable to stop the current output when the temperature of the power supply component detected by the temperature detecting means exceeds the high temperature stop temperature.

  According to such a configuration, the current output can be stopped when the temperature of the power supply component exceeds the dangerous temperature regardless of whether or not the output current exceeds the maximum allowable current value. For this reason, when there is a possibility of damage due to the high temperature of the power supply component even though the output current is low, the current output can be stopped and the deterioration / breakage of the power supply component can be more effectively suppressed. be able to.

  Moreover, it is preferable that it is an insulation type DC power supply device with which the power supply side and the load side were insulated.

  According to such a configuration, since the power supply side and the load side in the DC power supply device are insulated, when a large current caused by a short circuit or the like flows on one side of the power supply side or the load side, the other side may spread to the other side. Absent. For this reason, the safety | security of the power supply components in a DC power supply device improves.

  Moreover, it is preferable to provide a notification means for letting the user know the setting state of the maximum allowable current value by the maximum allowable current value setting means.

  According to such a configuration, the user can know the setting state of the maximum allowable current value. For this reason, the user can change to a work mode that does not overwork the power supply component according to the setting state of the maximum allowable current value, and can suppress deterioration and breakage of the power supply component with the change of the user work mode. it can.

  The present invention further includes an electric tool system including an electric tool having a motor and a DC power supply device that supplies driving power to the motor, wherein the DC power supply device is insulated from the power supply side and the motor side. And is configured to be directly connectable to the power tool, and the DC power supply further includes output current detection means for detecting output current, output current control means for controlling the output current, and maximum allowable A maximum allowable current value setting means for setting a current value, and a temperature detection means for detecting the temperature of the power supply component, and the maximum allowable current value setting means converts the set maximum allowable current value into the temperature. An electric power tool system is provided that changes according to the temperature of a power supply component detected by a detecting means.

  According to such a configuration, since the DC power supply device can be directly attached to and detached from the electric tool, it is possible to prevent the DC power supply device from interfering when the electric tool is used.

  According to the DC power supply device of the present invention, it is possible to perform continuous work for a long time while suppressing deterioration and breakage of power supply components. Furthermore, the power tool system according to the present invention can improve convenience.

It is a block diagram which shows the power supply circuit in the DC power supply device by embodiment of this invention. It is a figure which shows the flowchart showing control of the DC power supply device by embodiment of this invention. It is a figure which shows the temperature-current table which prescribed | regulated the relationship between the temperature of the power supply components used for control of the DC power supply device by embodiment of this invention, and a maximum permissible current value. It is a figure of the drooping characteristic which showed notionally the relation between the temperature of a power supply component, and the maximum allowable current value. It is a figure which shows the time displacement of the maximum allowable electric current value at the time of using the electric tool connected to the DC power supply device by embodiment of this invention, and the temperature of power supply components. It is a figure which shows the time displacement of the maximum allowable current value at the time of using the electric tool connected to the DC power supply device with which the conventional maximum allowable current value was fixed, and the temperature of power supply components. It is a figure which shows the relationship between the DC power supply device by embodiment of this invention, an electric tool, and a battery pack.

  A DC power supply device 1 according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram showing a configuration of a power supply circuit unit 10 in the DC power supply device 1 according to the present embodiment. The power supply circuit unit 10 is an insulating type including a high-frequency transformer 114, and includes a primary-side circuit unit 11, a secondary-side circuit unit 12, and a control circuit unit 13 of the high-frequency transformer 114. 1 is a circuit for supplying electric power to the electric power tool 3 in a state where the AC power source 2 and the electric power tool 3 are connected. Moreover, the DC power supply device 1 is configured to be directly connectable to the electric tool 3 as shown in FIG. A connection portion of the DC power supply device 1 to the electric tool 3 is configured in the same shape as a tool connection portion of a battery pack 300 (not shown) connected to the electric tool 3.

  The primary circuit unit 11 includes a primary rectifier circuit 111, a switching control circuit 112, an FET 113, and a high frequency transformer 114.

  The primary side rectifier circuit 111 can be connected to the AC power supply 2 on the input side, and is connected to the primary side winding of the high-frequency transformer 114 via the FET 113 on the output side. The primary side rectifier circuit 111 rectifies and smoothes the AC input from the AC power supply 2 and outputs the rectified and smoothed output to the high-frequency transformer 114.

  The switching control circuit 112 is connected to the gate of the FET 113, and performs so-called PWM control that changes the drive pulse width of the FET 113 based on a signal input from the control circuit unit 13 to control the output voltage.

  The FET 113 has a source connected to the primary side rectifier circuit 111 and a drain connected to the primary winding of the high-frequency transformer 114. The FET 113 is a switching element, and performs switching by making the drain and the source conductive or disconnected by a signal input to the gate from the switching control circuit 112.

  The high frequency transformer 114 is connected to the primary side rectifier circuit 111 via the FET 113, and steps down the output voltage from the primary side rectifier circuit 111 and transmits it to the secondary side circuit unit 12.

  The secondary side circuit unit 12 includes a rectification / smoothing circuit 121, a current detection circuit 122, a voltage detection circuit 123, a plus side connection terminal 12a, and a minus side connection terminal 12b.

  The rectifying / smoothing circuit 121 is connected to the secondary winding of the high-frequency transformer 114 on the input side, and connected to the plus side connection terminal 12a and the minus side connection terminal 12b on the output side. The rectifying / smoothing circuit 121 rectifies and smoothes the input from the high-frequency transformer 114 and outputs the rectified and smoothed circuit to the plus side connecting terminal 12a and the minus side connecting terminal 12b.

  The current detection circuit 122 is used as an output current detection means, is connected between the rectification / smoothing circuit 121 and the negative side connection terminal 12b, detects the output current flowing through the secondary side circuit unit 12, and detects the detection result. Is output to the control circuit unit 13.

  The voltage detection circuit 123 is connected in parallel with the rectification / smoothing circuit 121, detects the output voltage of the rectification / smoothing circuit 121, and outputs the detection result to the control circuit unit 13.

  The plus side connection terminal 12 a and the minus side connection terminal 12 b are output terminals provided on the output side of the secondary circuit 12, and can be electrically connected to the electric power tool 3.

  The control circuit unit 13 includes a control unit 131, an auxiliary power supply 132, a voltage control circuit 133, a power supply temperature detection unit 134, a voltage setting circuit 135, a status display unit 136, and a power supply cooling fan 137. .

  The auxiliary power supply 132 is connected to the output side of the primary side rectifier circuit 111, adjusts the output voltage of the primary side rectifier circuit 111 to a voltage that can be used as the power source of the control unit 131, and supplies it to the control unit 131. ing.

  The power supply temperature detection unit 134 serving as temperature detection means detects the temperature of each of the diodes (not shown) in the high-frequency transformer 114, the FET 113, and the rectification / smoothing circuit 121, which are power supply components, and outputs the result to the control unit 131. Yes.

  The control unit 131 is mainly used as an output current control unit and a maximum allowable current value setting unit, and includes a power supply input unit 131a, input ports 131b, 131c, and 131d, and output ports 131e, 131f, 131g, and 131h. A storage unit and an arithmetic unit (not shown). The power input unit 131a is connected to the auxiliary power source 132, and the control unit 131 is activated when a voltage from the auxiliary power source 132 is applied.

  The input port 131b is connected to the current detection circuit 122, and the detection result of the current detected by the current detection circuit 122 is input. The input port 131c is connected to the power supply temperature detection unit 134, and the detection result of the temperature of each power supply component detected by the power supply temperature detection unit 134 is input. The input port 131d is connected to the voltage detection circuit 123, and the detection result of the voltage detected by the voltage detection circuit 123 is input.

  The output port 131e is connected to the voltage setting circuit 135, and outputs a signal to the voltage setting circuit 135 in order to set the output voltage based on the voltage detection result input from the voltage detection circuit 123 to the port 131d. Yes. The output port 131f is connected to the switching control circuit 112, the temperature detection result of each power supply component input from the power supply temperature detection unit 134 to the input port 131c, and the current input from the current detection circuit 122 to the input port 131b. Based on the detection result, a signal for stopping power feeding to the electric power tool 3 is output to the switching control circuit 112 via a photocoupler (not shown). The output port 131g is connected to the status display unit 136, and outputs a signal for performing status display to the status display unit 136. The output port 131 h is connected to the power supply cooling fan 137 and outputs a control signal for controlling the rotation of the power supply cooling fan 137 to the power supply cooling fan 137.

  A storage unit (not shown) of the control unit 131 mainly stores a maximum allowable current value, a temperature current table, and a high temperature stop flag. The maximum allowable current value is a current value that is set in order to suppress deterioration or breakage of power supply components inside the DC power supply device 1 due to overcurrent. As shown in FIG. 3, the temperature / current table defines the relationship between the temperature of each power supply component and the maximum allowable current value. The high temperature stop flag is 1-bit information of 0 or 1. When at least one of the temperatures of each power supply component detected by the power supply temperature detection unit 134 exceeds the high temperature stop temperature corresponding to each power supply component in FIG. 3, the control unit 131 stores a high temperature in a storage unit (not shown). 1 is stored as the stop flag, and 0 is stored otherwise.

  The high temperature stop temperature is a temperature at which there is a high possibility of deterioration or damage of the power supply components, and is a temperature defined for each power supply component as a threshold value for determining whether or not to stop the current output.

  A computing device (not shown) performs computations, comparisons, and the like on the detection results input to the control unit 131.

  The voltage setting circuit 135 is connected to the port 131e of the control unit 131, and sets an output voltage based on a signal from the port 131e.

  The voltage control circuit 133 is connected to the voltage setting circuit 135, and based on the output voltage set by the voltage setting circuit 135 to control the output voltage, a control signal is sent via a photocoupler (not shown). 112 is output.

  The status display unit 136 is connected to the port 131g of the control unit 131. Based on the signal output from the port 131g, the status display unit 136 emits light in any one of the three colors of red, yellow, and green, and notifies the user. The state of the DC power supply device 1 is recognized. The status display unit 136 includes a red LED that emits red light and a green LED that emits green light, and causes only one of the red LED and the green LED to emit light based on a signal from the control unit 131. Alternatively, three colors of red, yellow, and green can be expressed by emitting both. When only the red LED emits light, the state display unit 136 emits red light, and when only the green LED emits light, the state display unit 136 emits green light. In addition, when both the red LED and the green LED are caused to emit light at the same time, the state display unit 136 emits yellow light.

  The power supply cooling fan 137 is connected to the port 131h of the control unit 131, and cools power supply components by changing the rotation speed based on a signal output from the port 131h.

  The electric tool 3 includes a motor 31 and a trigger switch 32, and has a connection portion (not shown) that can be electrically connected to the positive connection terminal 12a and the negative connection terminal 12b. When the trigger switch 32 is pulled in a state where the connection portion (not shown) and the plus connection terminal 12a and the minus connection terminal 12b are connected, and the current output is started, the rotating shaft of the motor 31 rotates and the electric tool 3 is driven.

  Next, control of the output operation of the DC power supply device 1 will be described with reference to the flowchart of FIG.

  First, when the AC power source 2 and the DC power source device 1 are connected, and the direct power source device 1 is further connected to the electric power tool 3 and the trigger switch 32 is pulled, the current output is not yet started and the process is temporarily stopped (step). 200). Next, it is determined whether the high temperature stop flag is 1 or 0 (step 201). If the high temperature stop flag is 1, it is determined whether the temperature is equal to or lower than the return temperature (step 202). The return temperature is a temperature defined for each power supply component as shown in FIG. 3, and at this temperature, it is determined that there is little risk of deterioration or damage even if a current is passed through each power supply component. Temperature. Specifically, the high frequency transformer 114 is 70 ° C., and the FET 113 and the diode (not shown) are 80 ° C. Further, it is determined that the temperature is not more than the return temperature only when all the temperatures of the high-frequency transformer 114, the FET 113, and the diode (not shown) are not more than the return temperature corresponding to each power supply component. When the temperature is equal to or lower than the return temperature, the control unit 131 stores a high temperature stop flag as 0 in a storage unit (not shown) (step 203), and outputs an output start signal from the port 131f to the switching control circuit 112. Then, the switching control circuit 112 to which the output start signal is input starts PWM control (step 204), and the electric power tool 3 is driven by the output current flowing through the secondary side circuit unit 12. On the other hand, if it is determined in step 202 that the temperature is not lower than the return temperature, steps 200, 201, and 202 are repeated, and the output stop state is maintained until it is determined in step 202 that the temperature is lower than the return temperature.

  When the current output is started and the output current starts to flow through the secondary side circuit unit 12, it is determined whether or not the temperature of each power supply component input from the power supply temperature detection unit 134 is equal to or lower than the T1 set temperature (step 205). ). As shown in FIG. 3, the T1 set temperature is a temperature defined for each power supply component shown in the leftmost column of the temperature / current table. Specifically, the T1 set temperature for the high-frequency transformer 114 is 50 ° C., the T1 set temperature for the FET 113 is 60 ° C., and the T1 set temperature for a diode (not shown) is 60 ° C. Similarly, the T2-T5 set temperature is also a temperature defined for each power supply component. For example, the T4 set temperature for the high-frequency transformer 114 is 90 ° C., and the T5 set temperature for the FET 113 is 110 ° C. In step 205, when all the temperatures of the power supply components are lower than the T1 set temperature corresponding to the power supply components, it is determined that the temperature is equal to or lower than the T1 set temperature, and any one of the temperatures of the power supply components is determined. However, if it is higher than the T1 set temperature for each power supply component, it is determined that it is not lower than the T1 set temperature.

  If it is determined in step 205 that the temperature is equal to or lower than the T1 set temperature, the maximum allowable current value is set to 50 A (step 206). On the other hand, if it is not below the T1 set temperature, it is determined whether or not it is below the T2 set temperature (step 207).

  If it is determined in step 207 that the temperature is equal to or lower than the T2 set temperature, the maximum allowable current value is set to 45 A (step 208). On the other hand, if it is not below the T2 set temperature, it is determined whether or not it is below the T3 set temperature (step 209).

  If it is determined in step 209 that the temperature is equal to or lower than the T3 set temperature, the maximum allowable current value is set to 40 A (step 210). On the other hand, if it is not lower than the T3 set temperature, it is determined whether it is lower than the T4 set temperature (step 209).

  If it is determined in step 209 that the temperature is equal to or lower than the T4 set temperature, the maximum allowable current value is set to 35 A (step 210). On the other hand, if it is not lower than the T4 set temperature, it is determined whether it is lower than the T5 set temperature (step 209).

  If it is determined in step 209 that the temperature is equal to or lower than the T5 set temperature, the maximum allowable current value is set to 10 A (step 210). On the other hand, if it is not below the T5 set temperature, it is determined whether or not it is below the high temperature stop temperature (step 211).

  If it is determined in step 211 that the temperature is equal to or lower than the high temperature stop temperature, the maximum allowable current value is set to 5 A (step 212). On the other hand, when the temperature is not lower than the high temperature stop temperature, the control unit 131 stores a high temperature stop flag as 1 in a storage unit (not shown) and outputs an output stop signal from the port 131f to the switching control circuit 112. The switching control circuit 112 to which the output stop signal has been input stops the PWM control and stops the driving of the power tool 3 (step 213). After stopping, the output stop state is maintained by repeating steps 201, 202, and 200 in order until the temperature of each power supply component becomes equal to or lower than the return temperature.

  In step 206, 208, 210, or 212, after the maximum allowable current value is set according to the temperature of the power supply component, the value of the output current detected by the current detection circuit unit 122 is compared with the maximum current value. (Step 214). When the output current value is larger than the maximum allowable current value, the output is stopped and the power supply to the power tool 3 is interrupted (step 215). On the other hand, when the output current value is equal to or less than the maximum allowable current value, the supply of power to the power tool 3 is continued, and the above-described steps are repeated from step 201 again. That is, the supply of electric power to the power tool 3 is not stopped until it is determined in step 211 that the temperature is equal to or higher than the high temperature stop temperature or the output current value is determined to be larger than the maximum allowable current value in step 214.

  Here, an example in which the maximum allowable current value is changed to a low value and an example in which the maximum allowable current value is changed to a high value are shown.

  As an example in which the maximum allowable current value is changed to a low value, it is determined in step 205 that the temperature is equal to or lower than the T1 set temperature. In step 206, the maximum allowable current value is set to 50 A without exceeding the maximum allowable current value. This is a case where the temperature of the power supply component exceeds the T1 set temperature but is below the T2 set temperature while repeating steps 201, 204, 205, 206, and 214 in this order. In this case, since it is determined in step 205 that the temperature is not lower than the T1 set temperature, and in step 207, it is determined that the temperature is equal to or lower than the T2 set temperature, the maximum allowable current value set to 50A is set to 45A in step 208. It will be.

  As an example in which the maximum allowable current value is changed to a high value, it is determined in step 207 that the temperature is equal to or lower than the T2 set temperature, and in step 208, the maximum allowable current value is set to 45 A without exceeding the maximum allowable current value. This is a case where the temperature of the power supply component falls to a temperature equal to or lower than the T1 set temperature while repeating steps 201, 204, 205, 207, 208, and 214 in this order. In this case, since it is determined in step 205 that the temperature is equal to or lower than the T1 set temperature, the maximum allowable current value set to 45A is set to 50A in step 206.

  In step 206, 208, 210, or 212, the status display unit 136 sets the maximum allowable current value according to the temperature of the power supply component, and simultaneously emits light in a color corresponding to each maximum allowable current value. When the maximum allowable current value is set to 50A or 45A in steps 206 and 208, the control unit 131 outputs a signal for causing only the green LED in the state display unit 136 to emit light, and the state display unit 136 emits green light. In step 210, when the maximum allowable current value is set to 40A, 35A, or 10A, the control unit 131 outputs a signal for causing both the red LED and the green LED in the state display unit 136 to emit light, and the state display unit. 136 emits yellow light. Further, when the maximum allowable current value is set to 5 A in step 212, the control unit 131 outputs a signal for causing only the red LED in the state display unit 136 to emit light, and the state display unit 136 emits red light. Thereby, the user can grasp | ascertain roughly the temperature condition of the electric tool 3, and the set maximum allowable electric current value by confirming the luminescent color of the state display part 136, and light-emits the usage condition of the electric tool 3. It can be changed according to the color. Alternatively, it is possible to display a stop only at the time of stop (one of the LEDs flashes), or at the time of stop, display a warning (for example, the other LED flashes) before the stop (for example, the state of T1).

  Next, the relationship between the temperature of the power supply component and the maximum allowable current value will be described with reference to FIG. FIG. 4 is a drooping characteristic diagram conceptually showing the relationship between the temperature of the power supply component and the maximum allowable current value defined in the above-described temperature-current table. The vertical axis in FIG. 4 represents the output voltage, and the horizontal axis represents the maximum allowable current value. In addition, T1 to Tn in FIG. 4 are T1 to Tn set temperatures that serve as threshold values for changing the maximum allowable current value. Although no specific temperature is shown, the temperature increases as the subscript n of T increases. Means. Further, when the temperature of the power supply component is a normal temperature, the maximum allowable current value is set to 50A. When the output current exceeds 50A, the output voltage becomes 0V, and the supply of power to the power tool is cut off. It means that. Similarly, when the temperature of the power supply component is higher than T1 and lower than or equal to T2, the maximum allowable current value is set to 40A. When the output current exceeds 40A, the output voltage becomes 0V, and power is supplied to the power tool. Means to be blocked.

  As described above, when the temperature of the power supply component is high, the deterioration or breakage of the power supply component can be suppressed by setting the maximum allowable current value low. In addition, by using the current within a range that does not exceed the maximum allowable current value, it is possible to suppress the high-temperature stop of the parts and to perform continuous work for a long time. Further, the maximum allowable current value can be set more finely by increasing the number of n.

  Next, a description will be given of the maximum allowable current value and the time displacement of the temperature of the power supply component with reference to FIGS.

  FIG. 5 shows the maximum allowable current value and the time displacement of the temperature of the power supply component when the electric power tool 3 connected to the DC power supply device 1 is used. FIG. 6 shows the time displacement of the maximum allowable current value and the temperature of the power supply component when using a power tool connected to a conventional DC power supply device whose maximum allowable current value is fixed at 50A.

  5 and 6 show the time displacement of the output current, and the lower diagram shows the time displacement of the temperature of the power supply component. For convenience of explanation, in FIG. 5 and FIG. 6, it is assumed that there is one power supply component to be monitored, and the output current value is a current value substantially equal to the maximum allowable current value. The current value does not exceed.

  As shown in FIG. 6, when the use of the power tool connected to the conventional DC power supply device is started (time t0), the temperature of the power supply component starts to rise. At this time, since the maximum allowable current value is fixed at 50A, the output current is 50A. If the power tool is continuously used, at time t1, the high temperature stop temperature (100 ° C.) is reached, and the power tool cannot be used until time t2 when the temperature of the power supply component decreases to the return temperature (80 ° C.). When the use of the power tool is started again at the time t2 with an output current of 50 A having a large temperature increase slope, the power tool reaches the high temperature stop temperature again at the time t3, and the power tool is lowered until the temperature of the power supply component decreases to the return temperature. Can no longer be used. In this way, the conventional power tool tends to reach a high temperature stop temperature when the power tool is used with the maximum output while the maximum allowable current value is fixed, and the temperature rise is always large. It becomes possible.

  On the other hand, when the use of the electric power tool 3 connected to the DC power supply device 1 is started as shown in FIG. 5, the temperature of the power supply component starts to rise with an inclination equal to the inclination of the temperature increase at time t <b> 0 to t <b> 1 in FIG. 6. . This is because the maximum allowable current value is set to 50A and the output current is 50A. If it continues to be used with an output current of 50A, it will reach the T1 set temperature (50 ° C) at time t10, but the maximum allowable current value is set to 45A, so the output current can only be output up to 45A, Compared to the case where the current is 50 A, the gradient of temperature rise is reduced. Similarly, at time t20, the temperature reaches the T2 set temperature (70 ° C.), and the maximum allowable current value is set to 40A. For this reason, the output current can only be output up to 40A, and the slope of the temperature rise is lower than that when the output current is 45A. In this way, since the slope of the temperature rise of the power supply components is gradually reduced, the time until the high temperature stop temperature (100 ° C.) is reached becomes longer and continuous use is possible.

  The DC power supply device according to the present invention is not limited to the above-described embodiment, and various modifications and improvements can be made within the scope described in the claims.

  In the above-described embodiment, the control for changing the maximum allowable current value corresponding to the absolute value of the power supply component temperature is adopted, but the maximum allowable current value corresponding to the temperature gradient of the power supply component temperature is set. You may employ | adopt the control to change. It is possible to change the maximum allowable current value corresponding to a sudden temperature change, and it is possible to more effectively suppress deterioration or breakage of power supply components.

1 .... DC power supply device, 2 .... AC power supply, 3 .... Electric tool, 31..Motor, 32..Trigger switch, 10..Power circuit section, 11..Primary side circuit section, 12..2 Secondary circuit section, 13 .... Control circuit section, 111 ... Primary side rectifier circuit, 112 ... Switching control circuit, 113 ... FET, 114 ... High frequency transformer, 121 ... Rectifier / smoothing circuit, 122 ... Current detection circuit, 123 ... Voltage detection circuit, 131 Control unit, 132, Auxiliary power supply, 133 Voltage control circuit, 134 Power temperature detection unit, 135 Voltage setting circuit, 136 Status display Part, 137 ... Power cooling fan, 300 ... Battery pack

Claims (7)

Output current detection means for detecting the output current;
Output current control means for controlling the output current;
A maximum allowable current value setting means for setting a maximum allowable current value;
Temperature detecting means for detecting the temperature of the power supply component,
A direct current power supply device in which the output current control means stops current output when the value of the output current exceeds the maximum allowable current value,
The maximum allowable current value setting means changes the set maximum allowable current value according to the temperature of the power supply component detected by the temperature detection means.   When the maximum allowable current value setting means outputs the current with the maximum allowable current value set to the first maximum allowable current value, the temperature detecting means corresponds to the first maximum allowable current value. When a temperature higher than the first specified upper limit temperature is detected, the maximum allowable current value setting means sets the maximum allowable current value to a second value that is lower than the first maximum allowable current value. The direct current power supply device according to claim 1, wherein the direct current power supply device is changed to a maximum allowable current value.   When the maximum allowable current value setting means outputs the current with the maximum allowable current value set to the third maximum allowable current value, the temperature detecting means corresponds to the third maximum allowable current value. When a temperature equal to or lower than the third specified lower limit temperature is detected, the maximum allowable current value setting means sets the maximum allowable current value to a fourth maximum value that is higher than the third maximum allowable current value. The DC power supply device according to claim 1, wherein the direct current power supply device is changed to an allowable current value.   4. The DC power supply device according to claim 1, wherein the current output is stopped when the temperature of the power supply component detected by the temperature detection unit exceeds a high temperature stop temperature. 5.   5. The DC power supply device according to claim 1, wherein the power supply side and the load side are insulated.   6. The DC power supply device according to claim 1, further comprising a notification unit configured to allow a user to know a setting state of the maximum allowable current value by the maximum allowable current value setting unit. An electric tool system comprising: an electric tool having a motor; and a DC power supply device that supplies driving power to the motor,
The DC power supply device is an insulating type in which the power supply side and the motor side are insulated, and is configured to be directly connectable to the electric power tool,
Furthermore, the DC power supply
Output current detection means for detecting the output current;
Output current control means for controlling the output current;
A maximum allowable current value setting means for setting a maximum allowable current value;
Temperature detecting means for detecting the temperature of the power supply component,
The maximum allowable current value setting means changes the set maximum allowable current value according to the temperature of the power supply component detected by the temperature detection means.

Images