JP5853676B2 - Brake failure alarm device and construction machine equipped with the same - Google Patents

Description

  The present invention relates to a technology that includes an electric motor that receives electric power to drive and generates electric power during braking, and a mechanical brake that applies a mechanical braking force to the electric motor, and warns of a failure of the mechanical brake.

  For example, the electric excavator described in Patent Document 1 includes a traveling unit, a turning unit, and a turning motor generator for turning the turning unit with respect to the traveling unit. The turning motor generator operates as a motor during a turning operation, and operates as a generator that exerts an electromagnetic brake action when the turning operation ends.

  In order to hold this type of generator in a stopped state, for example, as described in Patent Document 2, a mechanical brake is used. The mechanical brake is a negative brake that stops supplying the brake force to the generator in a state where a release command is given, and applies the brake force to the generator in a state where no release command is given.

  As described above, the generator is given a braking force accompanying the power generation when the drive is stopped, and is given a braking force by a mechanical brake when the generator is stopped.

  Here, when an abnormality occurs that makes it impossible to apply a braking force accompanying power generation to the generator, a mechanical brake must be used to stop the driving of the generator.

  However, since the mechanical brake is designed to keep the generator in a stopped state, there is a risk of malfunction when used to stop the drive of the generator.

JP 2001-207478 A JP-A-2005-290902

  Here, every time the mechanical brake is used to stop the driving of the generator, it can be considered that the mechanical brake is broken and an alarm is issued.

  However, if the load generated on the mechanical brake when the generator is stopped is low, it is assumed that the mechanical brake will not fail. In such a case, the work of checking, replacing or repairing the mechanical brake is useless.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a brake failure alarm device that can appropriately warn of the possibility of mechanical brake failure when the drive of an electric motor is stopped using a mechanical brake, and a construction machine equipped with the same. The purpose is to do.

In order to solve the above-mentioned problems, the present invention is a brake failure alarm device, wherein a driving object provided in a construction machine is driven to rotate according to the supply of electric power, and the power generation braking force accompanying power generation is An electric motor that can be supplied to an object to be driven, and a mechanical mechanical brake force is supplied to the electric motor in a state where no release command is input, while the mechanical brake force is supplied by inputting the release command And a control to stop the output of the release command to the mechanical brake when the motor is in a stopped state while outputting the release command to the mechanical brake during the drive period of the motor parts and the mechanical braking force is forcibly supplied to said electric motor even when the release command is outputted from the control unit An abnormality detection unit for detecting whether or not the vehicle is in an abnormal state, a speed detection unit for detecting the drive speed of the electric motor, and an alarm unit for warning that the mechanical brake may be broken down, When the abnormality detecting unit detects that the abnormal state is present, the drive speed of the electric motor detected by the speed detecting unit at the time of detection is equal to or higher than a specified speed value. A brake failure alarm that controls the operation of the alarm unit to warn of the possibility of a mechanical brake failure when the drive speed is determined to be equal to or greater than the speed prescribed value. Providing equipment.

  ADVANTAGE OF THE INVENTION According to this invention, when the drive of an electric motor is stopped using a mechanical brake, the possibility of generation | occurrence | production of the failure of a mechanical brake can be alert | reported appropriately. Specifically, in the present invention, when the drive speed of the electric motor at the time point when the abnormality detection unit detects that it is in an abnormal state is greater than or equal to the speed prescribed value, the possibility of mechanical brake failure is warned. In other words, if an electric motor that drives at a speed (speed specified value) or higher at which the mechanical brake is likely to fail is stopped by the mechanical brake force, it is estimated that the mechanical brake has failed and that is possible. Alarm. Therefore, it is possible to avoid alarming the possibility of failure of the mechanical brake when the electric motor that is driven at a low speed that does not cause the mechanical brake to fail is stopped.

  The “speed prescribed value” in the present invention is a speed at which the possibility that the mechanical brake will fail exceeds a specific threshold when a mechanical brake force is applied to the electric motor driven at that speed until it stops. Further, the “speed prescribed value” can be set in consideration of a load (inertia) assumed for the electric motor (or the driving object).

  In the brake failure alarm device, the abnormality detection unit has a switch that can be switched from a state that allows the release command to be transmitted to the mechanical brake from the control unit to a state that prevents the release command from being transmitted. Is preferred.

  In this aspect, by operating the switch, it is possible to switch from a state allowing the transmission of the release command to a state blocking it. Therefore, the electric motor can be mechanically locked by switching the switch when the operator feels something abnormal. Here, the abnormality felt by the operator is not limited to the operation of the electric motor. Therefore, it is not appropriate to warn that there is a possibility of failure of the mechanical brake every time the switch is switched. Here, since the control unit determines the failure of the mechanical brake according to the speed of the motor at the time of abnormality detection (switch switching time), the mechanical brake is operated even when the switch is operated due to various abnormalities. It is possible to appropriately warn of the possibility of failure.

  In the brake failure alarm device, an electric storage unit capable of charging electric power generated by the electric motor and capable of supplying the electric power charged to the electric motor, and a control power source capable of supplying electric power to the control unit And are preferably further provided.

  In this aspect, a control power source capable of supplying power to the control unit is provided separately from the battery that functions as the power source of the electric motor. As a result, even if an abnormality occurs in the electrical system connected to the capacitor, a warning of the possibility of a mechanical brake failure can be reliably performed by the power from the control power supply.

  The brake failure alarm device further includes an electric motor controller that is provided between the electric storage device and the electric motor, and controls electric power generation when the electric motor is driven and stopped according to a command from the control unit, The control power source is preferably capable of supplying power to the control unit even when an abnormality occurs in the motor controller.

  In this aspect, when an abnormality occurs in the motor controller, for example, when the braking of the motor by the power generation brake becomes uncontrollable, a warning of the possibility of a mechanical brake failure is reliably ensured by the power from the control power supply. Can be done.

  In the brake failure alarm device, an electric storage unit capable of charging electric power generated by the electric motor and capable of supplying the electric power charged to the electric motor, and a control power source capable of supplying electric power to the control unit And an electric motor controller that is provided between the electric storage device and the electric motor and controls power generation associated with driving and stopping of the electric motor according to a command from the control unit, Even when an abnormality occurs in the electric motor controller, a switch is provided that can be switched from a state that allows the release command to be transmitted to the mechanical brake from the control unit to a state that prevents the release command from being transmitted. However, it is preferable that the control power supply can supply power to the control unit even when an abnormality occurs in the motor controller.

  In this aspect, when an abnormality occurs in the motor controller, for example, when the braking of the motor by the power generation brake becomes uncontrollable, the control unit prevents the release command from being transmitted to the mechanical brake in response to the switch switching operation. As a result, it is possible to reliably issue a warning of the possibility of failure of the mechanical brake when the electric motor stops.

  The present invention also includes a construction machine main body, a revolving body provided so as to be able to turn with respect to the construction machine main body, and the brake failure alarm device. Provided is a construction machine capable of rotating a body in response to supply of electric power and supplying a power generation braking force accompanying power generation to the swivel body.

  ADVANTAGE OF THE INVENTION According to this invention, when the drive of an electric motor is stopped using a mechanical brake, the possibility of generation | occurrence | production of the failure of a mechanical brake can be alert | reported appropriately.

It is a right view which shows the whole structure of the hybrid shovel which concerns on embodiment of this invention. It is a block diagram which shows the drive control apparatus 5 of the hybrid shovel of FIG. It is a flowchart which shows the process performed by the controller shown in FIG.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. In addition, the following embodiment is an example which actualized this invention, Comprising: The thing of the character which limits the technical scope of this invention is not.

  Referring to FIGS. 1 and 2, a hybrid excavator 1 includes a lower traveling body (construction machine main body) 2, an upper revolving body 3 that is turnable on the lower traveling body 2, and the upper revolving body 3. Are provided with a work attachment 4 that can be raised and lowered, and a drive control device 5 (see FIG. 2) that controls the drive of the hybrid excavator 1.

  The lower traveling body 2 includes a pair of left and right crawlers 2a (only one is shown in FIG. 1), a left traveling motor 2b and a right traveling motor 2c (see FIG. 2) that supply traveling power to these crawlers 2a, A lower frame 2d provided between the crawlers 2a and a turning electric motor 2e (see FIG. 2) provided on the lower frame 2d for driving the upper turning body 3 to turn. As will be described in detail later, the swing electric motor 2e can drive the upper swing body 3 according to the supply of electric power, and can supply the upper swing body 3 with a power generation braking force accompanying power generation. In the present embodiment, the upper swing body 3 constitutes a driving object of the swing motor 2e. Hereinafter, the left traveling motor 2b and the right traveling motor 2c may be collectively referred to as the traveling motors 2b and 2c.

  The upper swing body 3 includes a swing frame 3a attached to the lower frame 2d so as to be swingable about an axis perpendicular to the ground.

  The work attachment 4 includes a boom 6 having a base end portion attached to the revolving frame 3 a so as to be able to undulate, an arm 7 having a base end portion swingably attached to the tip end portion of the boom 6, and a tip end of the arm 7. And a bucket 8 attached to the portion so as to be swingable. The work attachment 4 also has a boom cylinder 9 that raises and lowers the boom 6 relative to the revolving frame 3 a, an arm cylinder 10 that swings the arm 7 relative to the boom 6, and a bucket 8 that swings relative to the arm 7. A bucket cylinder 11 is provided. Hereinafter, the boom cylinder 9, the arm cylinder 10, and the bucket cylinder 11 may be collectively referred to as the cylinders 9 to 11.

  The drive control device 5 includes an engine 12, a hydraulic pump 14 driven by the engine 12, and a control valve 15 that controls supply and discharge of hydraulic oil from the hydraulic pump 14 to the travel motors 2 b and 2 c and the cylinders 9 to 11. A speed reduction mechanism 16 connected to the output shaft of the engine 12, a generator 17 connected to the speed reduction mechanism 16, a controller 18 electrically connected to the generator 17, and a controller 18 electrically The connected power battery (capacitor) 19 and inverter (electric motor controller) 20, the turning speed reduction mechanism 21 connected to the output shaft 2f of the turning electric motor 2e, and the turning speed for detecting the speed of the turning speed reduction mechanism 21 A sensor (speed detector) 22, a mechanical brake 23 capable of supplying a mechanical mechanical brake force to the output shaft 2f of the turning electric motor 2e, and a mechanical brake 2 A brake release valve 24 for releasing the engine, a sub pump 25 for supplying hydraulic oil to the mechanical brake 23 via the brake release valve 24, and an emergency stop button (abnormality detection unit) electrically connected to the brake release valve 24 26, a controller (control unit) 27 that outputs a command to the brake release valve 24 and the inverter 20, a turning operation lever 28 that outputs a drive command of the turning motor 2e to the controller 27, and a controller 27 A control battery (control power source) 29 capable of supplying electric power and an alarm unit 30 for executing an alarm in response to a command from the controller 27 are provided.

  The control valve 15 controls the travel and operation of the work attachment 4 by controlling the supply and discharge of hydraulic oil from the hydraulic pump 14 to the travel motors 2 b and 2 c and the cylinders 9 to 11.

  The generator 17 generates power using the power of the engine 12 input via the speed reduction mechanism 16. Further, the generator 17 assists in driving the engine 12 by receiving power supply from the power battery 19.

  The controller 18 is provided between the generator 17 and the power battery 19 and controls the operation of the generator 17. Specifically, the controller 18 supplies power from the power battery 19 to the generator 17 when the generator 17 performs a power running operation. On the other hand, the controller 18 charges the power battery 19 with the electric power generated by the generator 17 when the generator 17 is performing the regenerative operation.

  The inverter 20 is provided between the swing motor 2e and the power battery 19, and controls the operation of the swing motor 2e according to a command from the controller 27 described later. Specifically, the inverter 20 supplies electric power from the power battery 19 to the swing motor 2e when the swing motor 2e performs a power running operation. On the other hand, the inverter 20 charges the power battery 19 with the electric power generated by the swing motor 2e when the swing motor 2e is performing regenerative operation (braking braking). Moreover, the inverter 20 controls the load in braking of the turning electric motor 2e.

  The turning deceleration mechanism 21 transmits the turning driving force by the turning electric motor 2e to the upper turning body 3 while decelerating.

  The mechanical brake 23 is a negative brake capable of supplying a mechanical brake force to the output shaft 2f of the turning electric motor 2e. Specifically, the mechanical brake 23 supplies a mechanical brake force to the turning electric motor 2e in a state where no release command is input from the controller 27 described later. On the other hand, the mechanical brake 23 stops the supply of the mechanical brake force when the release command is input. The release command input to the mechanical brake 23 is hydraulic oil supplied from the sub pump 25.

  The brake release valve 24 controls supply / discharge of hydraulic oil from the sub pump 25 to the mechanical brake 23. Specifically, the brake release valve 24 can be switched between a switching position A for guiding hydraulic oil in the mechanical brake 23 to the tank T and a switching position B for guiding hydraulic oil from the sub pump 25 to the mechanical brake 23. . The brake release valve 24 is normally urged to the switching position A, while being switched to the switching position B when a release command from the controller 27 is input to the solenoid. That is, the release command for the mechanical brake 23 includes an electrical signal output from the controller 27 and a hydraulic pressure signal input to the mechanical brake 23.

  The emergency stop button 26 detects whether or not the emergency stop button 26 is in an abnormal state in which the supply of the mechanical brake force to the swing electric motor 2e is forcibly maintained even when a release command is output from the controller 27. Specifically, the emergency stop button 26 permits the transmission of a release signal (electric signal) from the controller 27 to the mechanical brake 23 (the state shown in FIG. 2) and prevents the transmission of the release signal (see FIG. 2). A switch that can be switched between a state in which the contact is cut off). When the operator feels any abnormality in the operation of the hybrid excavator 1, the operator can mechanically lock the swing motor 2e with the mechanical brake 23 by operating the switch. Specifically, since the emergency stop button 26 is connected to the controller 27 via a path different from that of the inverter 20, even when an abnormality occurs in the inverter 20, the emergency stop button 26 enters a state in which transmission of the release command is blocked. Switching operation is possible. Therefore, the operator can mechanically lock the swing motor 2e by switching the emergency stop button 26 when the swing motor 2e becomes uncontrollable, for example. Furthermore, the emergency stop button 26 detects that the switch contact has been disconnected, and outputs an electrical signal to that effect to the controller 27.

  The controller 27 outputs a release command to the mechanical brake 23 during the driving period of the swing motor 2e, and stops outputting the release command to the mechanical brake 23 when the swing motor 2e is in a stopped state.

  Specifically, when a drive command for the swing motor 2e is input from the swing operation lever 28, the controller 27 outputs a command to the inverter 20 that power should be supplied from the power battery 19 to the swing motor 2e. Then, a release command for switching the brake release valve 24 to the switching position B is output to the solenoid of the brake release valve 24. On the other hand, the controller 27 stops the output of the release command to the brake release valve 24 when the turning electric motor 2e is in a stopped state. The stopped state of the swing motor 2e includes not only the case where the drive speed of the swing motor 2e is 0, but also the case where the swing motor 2e is driven at a low speed that can be regarded as stopped. .

  Further, when the emergency stop button 26 detects that the controller 27 is in an abnormal state, the controller 27 determines whether or not the drive speed of the turning electric motor 2e detected by the turning speed sensor 22 at the time of detection is equal to or higher than a specified speed value. When the drive speed is determined to be equal to or higher than the speed prescribed value, a command for warning the failure of the mechanical brake 23 is output to the alarm unit 30.

  Specifically, the controller 27 stores a speed regulation value. The speed regulation value is a speed at which the possibility that the mechanical brake 23 will fail exceeds a specific threshold when a mechanical brake force is applied to the turning electric motor 2e driven at that speed until it stops. The speed regulation value can also be set in consideration of a load (inertia) assumed for the swing motor 2e or the upper swing body 3 (particularly, the work attachment 4). Therefore, when the turning electric motor 2e that is driven at a speed equal to or higher than the speed regulation value is stopped using the mechanical brake 23, the possibility that the mechanical brake 23 breaks down is extremely high. The controller 27 identifies a situation where there is a high possibility of failure of the mechanical brake 23 and outputs it to the alarm unit 30.

  The alarm unit 30 warns that the mechanical brake may be broken. Specifically, the alarm unit 30 can output a warning that the mechanical brake may be broken as visual information and / or auditory information. Note that a stop operation unit (not shown) for stopping the alarm by the alarm unit 30 is electrically connected to the controller 27. This stop operation unit is operated by a service person who performs maintenance management of the hybrid excavator.

  The control battery 29 can supply power to the controller 27 even when an abnormality occurs in the inverter 20. Specifically, the control battery 29 is connected to the controller 27 through a path different from that of the inverter 20. As described above, since the control battery 29 is provided separately from the power battery 19, even if an abnormality occurs in the electric system connected to the power battery 19, the mechanical power is supplied from the control battery 29. An alarm for failure of the brake 23 can be reliably performed.

  Hereinafter, processing executed by the controller 27 will be described with reference to FIG.

  When the process is started, it is first determined whether or not the turning operation lever 28 has been operated (step S1). If it is determined that the turning operation lever 28 has been operated, the mechanical brake 23 is released (step S2) and the turning electric motor 2e is driven (step S3). That is, when the turning operation lever 28 is operated, the mechanical brake force for the turning electric motor 2e is released, and the electric power charged in the power battery 19 or the electric power generated by the generator 17 is supplied to the turning electric motor 2e.

  Next, it is determined whether or not the emergency stop button 26 is turned on (step S4). That is, it is determined whether or not the switch of the emergency stop button 26 is operated in a state where the transmission of the release command from the controller 27 to the mechanical brake 23 is blocked.

  In the present embodiment, step S4 is performed not only in a state where the turning operation lever 28 is operated (a state via steps S1 to S3) but also in a state where the turning operation lever 28 is not operated (NO in step S1). Is executed. Step S4 is executed in a state where the turning operation lever 28 is not operated, even when the turning operation lever 28 is not operated, the turning electric motor 2e is driven as in the braking period of the turning electric motor 2e. This is because the situation exists.

  If it is determined in step S4 that the emergency stop button 26 is ON, the drive speed of the turning electric motor 2e at that time is detected (step S5). That is, in step S5, the speed of the swing electric motor 2e at the time when braking of the swing electric motor 2e is started by the mechanical brake 23 is detected.

  Next, it is determined whether or not the drive speed of the swing motor 2e is equal to or greater than a speed regulation value (step S6). That is, it is determined whether or not the speed at the start of braking of the swing electric motor 2e is equal to or higher than the speed at which the mechanical brake 23 is likely to break down.

  If it is determined in step S6 that the drive speed is equal to or greater than the speed prescribed value, the alarm unit 30 warns that the brake needs to be inspected, that is, the mechanical brake 23 may be broken. The operator who sees this can recognize the possibility of failure of the mechanical brake 23 and the necessity of having a serviceman check it.

  The alarm by the alarm unit 30 is continued until an alarm stop operation is performed by a service person (NO in step S8). On the other hand, when an alarm stop operation is performed by the service person, the alarm is stopped (step S9).

  Then, after the alarm is stopped (after step S9) or when the drive speed is less than the speed prescribed value (NO in step S6), the system waits for the emergency stop button 26 to be turned off (step S10). . That is, the controller 27 waits for a release command to be transmitted to the solenoid of the brake release valve 24. Then, when the emergency stop button 26 is turned off, the process ends.

  As described above, according to the embodiment, it is possible to appropriately warn of the possibility of the failure of the mechanical brake 23 when the mechanical brake 23 is used to stop the driving of the turning electric motor 2e. Specifically, in the above-described embodiment, when the drive speed of the swing motor 2e at the time point when the emergency stop button 26 detects an abnormal state is equal to or higher than the speed regulation value, a warning is given to the possibility of a failure of the mechanical brake 23. To do. In other words, when the turning electric motor 2e that is driven at a speed (speed specified value) or higher at which the mechanical brake 23 is likely to fail is stopped by the mechanical brake 23, it is estimated that the mechanical brake 23 has failed, and the possibility Alarm that there is. Therefore, it is possible to avoid alarming the possibility of failure of the mechanical brake 23 when the turning electric motor 2e that is driven at a low speed that does not cause the mechanical brake 23 to fail is stopped.

  In the embodiment, by operating the switch of the emergency stop button 26, it is possible to switch from a state where the transmission of the release command is permitted to a state where it is blocked. Therefore, the turning electric motor 2e can be mechanically locked by switching the switch when the operator feels something abnormal. Here, the abnormality felt by the operator is not limited to the operation of the turning electric motor 2e. Therefore, it is not appropriate to warn that the mechanical brake 23 has failed every time the switch is switched. Here, since the controller 27 determines the failure of the mechanical brake 23 according to the speed of the turning electric motor 2e at the time of abnormality detection (switch switching time), even when the switch is operated with various abnormalities. A possibility of failure of the mechanical brake 23 can be appropriately warned.

  In the said embodiment, the control battery 29 which can supply electric power to the controller 27 separately from the power battery 19 which functions as a power supply of the turning electric motor 2e is provided. As a result, even if an abnormality occurs in the electric system connected to the power battery 19, it is possible to reliably issue a warning of the possibility of failure of the mechanical brake 23 by the electric power from the control battery 29.

  In the above embodiment, when an abnormality occurs in the inverter 20, that is, when the braking of the turning motor 2 e by the power generation brake becomes uncontrollable, there is a possibility that the mechanical brake 23 may be broken by the power from the control battery 29. The alarm can be performed reliably.

  In the embodiment, when an abnormality occurs in the inverter 20, for example, when braking of the turning motor 2e by the power generation brake becomes uncontrollable, the controller 27 releases the mechanical brake 23 from the controller 27 according to the operation of the emergency stop button 26. It is possible to prevent the command from being transmitted, and to reliably alert the possibility of failure of the mechanical brake 23 when the turning electric motor 2e is stopped.

  In the above-described embodiment, the turning speed sensor 22 detects the speed of the turning speed reduction mechanism 21. However, the turning speed sensor 22 may directly detect the speed of the turning electric motor 2e. In this case, the speed regulation value stored in the controller 27 needs to be set as the speed of the turning electric motor 2e.

  In the above embodiment, the swing electric motor 2e for driving the upper swing body 3 to rotate is described as an example of the electric motor, but the present invention is not limited to the swing electric motor 2e. For example, the above-described control can be performed for a winch motor that rotationally drives a winch drum provided in a crane.

1 Hybrid excavator (an example of construction machinery)
2 Lower traveling body (an example of a construction machine body)
2e Swing motor (an example of an electric motor)
3 Upper revolving structure (an example of a driven object)
19 Power battery (an example of a battery)
20 Inverter (an example of a motor controller)
22 Turning speed sensor (example of speed detector)
23 Mechanical brake 26 Emergency stop button (an example of an abnormality detection unit)
27 Controller (Example of control unit)
29 Control battery (an example of a turning power supply)
30 Alarm section

Claims (6)

Brake failure alarm device,
An electric motor capable of rotating and driving a driving object provided in the construction machine according to the supply of electric power, and supplying a power generation braking force accompanying power generation to the driving object;
A mechanical brake that supplies mechanical mechanical brake force to the electric motor in a state where a release command is not input, while stopping the supply of the mechanical brake force when the release command is input;
A controller that outputs the release command to the mechanical brake during the driving period of the electric motor, and stops the output of the release command to the mechanical brake when the motor is in a stopped state;
An abnormality detection unit for detecting whether or not the mechanical brake force for the electric motor is forcibly supplied even when the release command is output from the control unit;
A speed detector for detecting the driving speed of the electric motor;
An alarm unit for alarming that the mechanical brake may be broken,
When the abnormality detecting unit detects the abnormal state, the control unit determines whether the driving speed of the electric motor detected by the speed detecting unit at the time of detection is equal to or higher than a specified speed value. A brake failure alarm device that determines and controls the operation of the alarm unit to warn of the possibility of mechanical brake failure when it is determined that the drive speed is equal to or greater than the speed prescribed value.
  2. The brake according to claim 1, wherein the abnormality detection unit includes a switch that can be switched from a state in which transmission of the release command to the mechanical brake from the control unit is permitted to a state in which transmission of the release command is blocked. Fault alarm device. A battery capable of charging the electric power generated by the electric motor and capable of supplying the electric power charged to the electric motor;
The brake failure alarm device according to claim 1, further comprising a control power source capable of supplying power to the control unit. An electric motor controller which is provided between the electric storage device and the electric motor, and controls electric power generation associated with driving and stopping of the electric motor according to a command from the control unit;
4. The brake failure alarm device according to claim 3, wherein the control power supply can supply power to the control unit even when an abnormality occurs in the motor controller. 5. A battery capable of charging the electric power generated by the electric motor and capable of supplying the electric power charged to the electric motor;
A control power supply capable of supplying power to the control unit;
An electric motor controller that is provided between the electric storage device and the electric motor, and controls electric power generation associated with driving and stopping of the electric motor according to a command from the control unit;
The abnormality detection unit switches from a state in which transmission of the release command to the mechanical brake is permitted from the control unit to a state in which transmission of the release command is blocked even when an abnormality occurs in the motor controller. Has an operable switch,
The brake failure according to any one of claims 1 to 4, wherein the control power supply can supply power to the control unit even when an abnormality occurs in the motor controller. Alarm device. The construction machine body,
A revolving structure provided to be rotatable with respect to the construction machine body;
The brake failure alarm device according to any one of claims 1 to 5,
The electric motor of the brake failure alarm device is a construction machine capable of rotating the swivel body according to the supply of electric power and supplying a power generation brake force accompanying power generation to the swivel body.

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