JP3388620B2 - Excavator drive motor overload protection device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for shutting off a contactor when the temperature of a drive motor for rotating a drilling tool such as an auger screw becomes higher than an allowable maximum temperature. The present invention relates to an overload protection device for an excavator drive motor that protects a drive motor by using the same. 2. Description of the Related Art Conventionally, in order to protect a drive motor for rotating a drilling tool such as an auger screw from burning or the like, a connection to a power source is cut off when an overload occurs. An overload protection device is used. As such a device, for example, a so-called thermal relay is known in which a heater is wound around a bimetal, a motor current is supplied to the heater, and a bimetal is bent to open a contact due to an increase in the motor current due to an overload. . [0003] In a situation where the contactor is cut off, the load applied to the drive motor is usually large continuously, and even if the drive motor can be restarted, In such a situation, it is difficult to dig further. In addition, since the ground after excavation becomes easier to tighten with the passage of time, it is preferable that the excavator be pulled out of the ground once by immediately restarting after the drive motor is stopped, rotating the drive motor reversely, or the like. [0004] However, in such conventional devices,
Even if an attempt is made to restart the drive motor, it cannot be restarted immediately because it is overheated. For example, immediately after the stop, the temperature of the drive motor is still higher than the maximum allowable temperature, and it is necessary to wait until the drive motor cools and becomes lower than the maximum allowable temperature. Moreover, the thermal relay cannot be reset and cannot be restarted immediately until the bimetal cools down. [0005] Therefore, there is a problem that the ground becomes tight and cannot be pulled out, so that it is necessary to excavate the digging tool separately or that the digging tool has to be left in the ground. there were. Therefore, an object of the present invention is to provide an overload protection device for an excavator drive motor that can promptly restart a drive motor that has been stopped because a contactor has been shut off, with the object of solving the above problem. Means for Solving the Problems In order to achieve the above object, the present invention has the following structure as means for solving the problems. That is, a temperature detecting means for detecting a temperature of a drive motor for rotationally driving an excavating tool for excavating underground, and a relay for an allowable maximum temperature when the temperature exceeds the allowable maximum temperature.
-An overload protection device for an excavator drive motor, which comprises an allowable cutoff means for opening a contact and shutting off a contactor, and cutting off from a power supply when the temperature exceeds the allowable maximum temperature to protect the drive motor. When the temperature of the drive motor is equal to or higher than the stop temperature which is lower than the allowable maximum temperature by a predetermined temperature, a forward contact switch contact and a reverse contact connected in parallel with the forward contact switch contact
Between the switch contact and the relay contact for the maximum allowable temperature
A stop interrupting means for interrupting the contactor to open the stop temperature relay contact provided in series, after being stopped by said stop blocking means, regardless of the interruption of the contactor according to the stop blocking means, the forward rotation Switch or switch for reverse rotation
The forward switch contact or the
Close the switch contact for reverse rotation and the emergency escape switch.
While the switch is pressed, it is in parallel with the stop temperature relay contact.
And an emergency escape means for closing the emergency escape switch contact provided to connect the contactor to rotate the drive motor. is there. [0007] In the overload protection device for an excavator drive motor having the above-mentioned structure, the temperature detecting means detects the temperature of the drive motor, and the stop / shutoff means sets the temperature of the drive motor at or above the stop temperature. When the stop temperature relay contact is opened, the contactor is shut off and the drive motor is stopped. And, regardless of whether the emergency escape means shuts off the contactor by the stop shutoff means,
When the forward switch or reverse switch is pressed,
Since the contact motor is connected to rotate the drive motor while the emergency escape switch is pressed, the excavator can be quickly pulled out from the ground. On the other hand, when the temperature of the drive motor becomes equal to or higher than the maximum allowable temperature, the allowable cutoff means shuts off the contactor to stop the drive motor, thereby protecting the drive motor from a serious failure such as burning. Embodiments of the present invention will be described below in detail with reference to the drawings. As shown in FIG. 2, reference numeral 1 denotes a construction machine, and a leader 2 is supported by a stay 4 and a catching fork 6 so that the leader 2 can be turned upside down. Two long guide rails 8 and 10 are laid on the front surface of the reader 2 along its longitudinal direction. The guide rails 8 and 10 each having a circular cross section have four guide gibs 14 formed of a casing 12. 17 are engaged. An auger driving device 18 is provided in the casing 12.
And one end of a wire 24 wound around the sheave 22 is fastened to the upper end of the reader 2 and the other end is rotated to the upper end of the reader 2. A pair of sheaves 26 which are supported as possible,
28. Then, it is wound around a rotary drum of a winch (not shown) provided inside the construction machine 1 via a sheave 30 rotatably supported in the middle of the leader 2 and a sheave 32 provided at a lower end of the leader 2. . The auger driving device 18 has a three-phase AC type driving motor 34 mounted on the casing 12, and the driving motor 34 is provided with a digging tool 20 such as an auger screw through a speed reducer 36 and a joint 38. It is connected. A temperature sensor 40 for detecting the temperature of the drive motor 34 is attached to the drive motor 34 at a winding end (not shown) of the drive motor 34. A platinum thin film temperature sensor is used as the temperature sensor 40, and the platinum thin film temperature sensor is
4 may be attached to a winding or the like (not shown). As shown in FIG. 1, the drive motor 34 is connected to a power supply 44 via a control panel 42. The power supply 44 includes a generator 48 that is driven to rotate by an internal combustion engine 46. , The power generated by the generator 48 is 3
It is connected so as to be supplied to the drive motor 34 via the phase power line 50. [0013] power line 50 in the control cabinet 42, the forward rotation tangent
Together with the main contact 52 of the touch device (a contact) is interposed, the main contact 54 of the reverse rotation contactor (a contact) is, with respect to the main contacts 52 of the forward rotation contactor, the three-phase power line 50 It is interposed so that these two phases are exchanged. The temperature sensor 40 is connected to an input terminal 56a of a permissible comparator 56. The output voltage of a setting device 58 for setting the permissible maximum temperature TA is supplied to the permissible comparator 5.
6 are connected so as to be input to the other input terminals 56b. Here, the allowable maximum temperature TA set in the allowable comparator 56 is a temperature at which the continuous operation can be performed without any trouble below the allowable temperature. For example, if the drive motor 34 is continuously operated at a higher temperature, deterioration of insulation and the like will occur. Is a temperature that may lead to The permissible comparator 56 outputs a high-level signal when the temperature detected by the temperature sensor 40 exceeds the permissible maximum temperature TA. The temperature sensor 40 is also connected to the input terminal 60a of the stop comparator 60. The output voltage of the setting device 62 for setting the stop temperature TE is applied to another input terminal 60b of the stop comparator 60. Connected to be input.
The stop comparator 60 outputs a high-level signal when the temperature detected by the temperature sensor 40 becomes equal to or higher than the stop temperature TE. The stop temperature TE is the maximum allowable temperature TA.
For example, it is a temperature that is lower than the allowable maximum temperature TA by estimating the temperature rise expected during the operation of pulling out the digging tool 20 restrained in the ground to the ground before reaching the allowable maximum temperature TA. . When the temperature of the drive motor 34 becomes equal to or higher than the stop temperature TE, the drive motor 34 is once stopped, and when the drive motor 34 is driven again, the temperature of the drive motor 34 further rises and the allowable maximum temperature TA Is set so that the digging tool 20 can be rotated and pulled out to the ground before reaching. The output side of the allowable comparator 56 is connected to an excitation circuit 64
The excitation circuit 64 is configured to excite the coil RTA of the maximum allowable temperature relay when the signal from the allowable comparator 56 is at a high level. The output side of the stop comparator 60 is connected to the excitation circuit 66, and the excitation circuit 66 is configured to excite the coil RTE of the relay for the stop temperature when the signal from the stop comparator 60 is at a high level. Have been. On the other hand, one end of the coil FMC of the forward contactor is connected to one phase of the power line 50, and the other end is connected to the stop switch contact 70 (b contact) via the forward switch contact 68 (a contact). )It is connected to the. The auxiliary contact 53 of the forward contactor is connected in parallel with the forward switch contact 68.
(A contact) is connected. One end of the coil RMC of the reverse contactor is connected to one phase of the power line 50, and the other end is connected to the stop switch contact 70 via the reverse switch contact 72 (a contact). ing. Then, in parallel with the reverse rotation switch contact 72, reverse rotation contactor auxiliary contact 55 (a contact)
Is connected. The stop switch contact 70 is connected to the other phase of the power line 50 via a stop temperature relay contact 74 (contact b) and then via an allowable maximum temperature relay contact 78 (contact b). An emergency escape switch contact 80 (a contact) is connected in parallel to the stop temperature relay contact 74. The forward rotation switch, the reverse rotation switch, the stop switch, and the emergency escape switch are provided on an operation panel 82 provided in the cab 1 a of the construction machine 1. In this embodiment, the permissible shutoff means is constituted by the permissible comparator 56, the setting device 58, the excitation circuit 64 and the permissible maximum temperature relay, and the stop comparator 60, the setting device 62, and the excitation circuit 66 The stop temperature interrupting means is constituted by the stop temperature relay. The emergency escape switch, the forward rotation switch, and the reverse rotation switch constitute an emergency escape means. Next, the operation of the above-described overload protection device for an excavator driving motor according to the present embodiment will be described. When a winch (not shown) is driven to wind up the wire 24, the casing 12 is pulled up via the sheave 22. Thereby, the casing 12 moves up along the guide rails 8 and 10. Then, when the winch is driven and the wire 24 is paid out, the casing 12 descends along the guide rails 8 and 10 by the weight of the casing 12 and the auger driving device 18. When the internal combustion engine 46 is operated and the generator 4
8, when the forward rotation switch is pressed by the operator and the contact 68 is closed, the forward rotation contact
The coil FMC of the touch device is excited. Accordingly , the main contact 52 of the forward contactor is closed to drive the drive motor 34 to rotate, and the auxiliary contact 53 is closed to excite the coil FMC by itself. Therefore, even if the operator releases the forward rotation switch to open the contact 68, the rotational drive of the drive motor 34 is continued. Thus, the excavator 20 is rotated via the reduction gear 36 and the joint 38, and excavation is performed. On the other hand, when the reverse switch is pressed, the contact 7
2 is closed , the coil RMC of the reverse contactor is excited , the main contact 54 of the reverse contactor is closed, and the drive motor 3 is closed.
4 is driven in reverse rotation, the auxiliary contact 55 is closed, the excitation of the coil RMC is self-held, and the excavator 20 is rotated in reverse. When the stop switch is pressed and the contact 70 is opened during the normal rotation of the drive motor 34, the coil FM
C is demagnetized , the main contact 52 of the forward contactor is opened, the rotation of the drive motor 34 is stopped, and the auxiliary contact 53 is opened to release the self-holding. Also during the reverse rotation, the coil RMC is similarly demagnetized and the reverse rotation is stopped. For example, if the digging tool 20 hits against a hard rock or the like while the digging tool 20 is rotating in the normal direction, the load of the drive motor 34 increases and an overcurrent flows. Overcurrent flows continuously, the temperature of the winding of the drive motor 34 rises, and the temperature detected by the temperature sensor 40 becomes the stop temperature T.
If E or more, a high level signal is output from the stop comparator 60, the exciting circuit 66 excites the coil RTE of the stop temperature relay, and the stop temperature relay contact 74 opens. Thus, the coil FMC of forward rotation contactor is demagnetized, the drive motor 34 main contacts 52 of the forward rotation contactor opens
Is stopped. In this state, the ground is tightened with the passage of time and the excavator 20 does not come off, so that the emergency escape switch is immediately pressed to close the contact 80, and at the same time, the forward switch or the reverse switch is turned on. Press one. At this time, since the temperature of the drive motor is equal to or lower than the allowable maximum temperature TA, the allowable maximum temperature relay contact 78 is in a closed state. For example, when the emergency escape switch and the reverse rotation switch are simultaneously pressed , the coil RMC of the reverse rotation contactor is pressed.
Are reverse switch contact 72 and stop switch contact 7
0, the emergency escape switch contact 80 is excited via the relay contact 78 for the maximum allowable temperature, and the reverse rotation switch is self-holding. Therefore, while the emergency escape switch is pressed,
The drive motor 34 is driven in reverse rotation. During this reverse rotation, the wire 24 is wound up and the drilling tool 20 is pulled out from the ground. By closing the emergency escape switch contact 80, even if the temperature of the drive motor 34 is equal to or higher than the stop temperature TE, regardless of the temperature , the coil RM of the reverse contactor is used.
C is excited, the excavating tool 20 is rotated in the reverse direction, and the excavating tool 20 is pulled out from the digged rock or the like. At this time, since the temperature of the drive motor 34 has not yet reached the maximum allowable temperature TA, even if the drive motor 34 is rotationally driven, no trouble such as deterioration of the insulator is caused and no serious trouble such as burning is caused. Then, the excavator 20 is pulled out from the ground until the temperature reaches the allowable maximum temperature TA. If the temperature of the drive motor 34 reaches the maximum allowable temperature TA
Is reached, the temperature sensor 40 detects this, and the permissible comparator 56 outputs a high-level signal. Thereby, the coil RTA of the relay for the maximum allowable temperature is excited, the relay contact 78 for the maximum allowable temperature is opened, the coil RMC of the contactor for reverse rotation is demagnetized, the drive motor 34 is stopped, and the deterioration of the insulator, etc. Prevents serious failures such as burning. [0031] In this embodiment, since the detected temperature of the drive motor 34 directly by the temperature sensor 40, without being affected by the external environment, as possible out to protect the drive motor 34. The allowable maximum temperature TA is equal to the absolute value of the drive motor 34.
It is an absolute value determined by the edge performance, whereas
When the outside air temperature is high and low even if the load is the same
, The temperature of the drive motor 34 is higher than the allowable maximum temperature TA.
There are times when it becomes and times when it does not. Detect temperature directly
Without being affected by the outside air temperature.
The drive motor 34 can be protected. As described above, the present invention is not limited to such embodiments at all, and can be implemented in various modes without departing from the gist of the present invention. As described in detail above, the overload protection device for an excavator drive motor according to the present invention shuts off the drive motor by the contactor when the temperature of the drive motor becomes higher than the stop temperature. Stop. Then, regardless of whether the contactor is shut off, press the forward switch or reverse switch.
Also, while the emergency escape switch is pressed, the contactor can be connected again and the drive motor can be rotated, so that the temperature of the drive motor rises to the maximum allowable temperature and is cut off from the power supply by the contactor. Before the drilling, the drilling tool can be pulled out of the ground.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration diagram of an overload protection device for an excavator drive motor as one embodiment of the present invention. FIG. 2 is a front view of a construction machine using the overload protection device for an excavator driving motor according to the present embodiment. [Description of Signs] 1 ... Construction Machine 18 ... Auger Drive
Reference numeral 20: excavator 34: drive motor 40: temperature sensor
56: allowable comparator 60: stop comparator 74: relay contact for stop temperature 78: relay contact for allowable maximum temperature
82 Operation panel

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A 52-31165 (JP, U) JP-B 51-26966 (JP, B2) JP-B 5-3841 (JP, Y1) 504193 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) E02F 3/00 H02H 7/00 H02P 7/00 E21B 3/00 H02P 1/00

Claims (1)

(57) [Claims 1] Temperature detecting means for detecting the temperature of a drive motor for rotating and driving an excavating tool for excavating underground, and permitting when the temperature becomes equal to or higher than an allowable maximum temperature. Maximum temperature relay
An allowable cut-off means for opening the contact and shutting off the contactor,
In an overload protection device for an excavator drive motor that protects the drive motor by cutting off from a power supply when the temperature becomes equal to or higher than the allowable maximum temperature, the temperature of the drive motor is a stop temperature equal to or lower than a predetermined temperature lower than the allowable maximum temperature. Switch contact for forward rotation when
And a reverse switch contact connected in parallel with the
Stop provided in series with the maximum temperature relay contact
A stop / off means for opening a temperature relay contact to cut off the contactor; and a switch for normal rotation after being stopped by the stop / off means, regardless of the cutoff of the contactor by the stop / off means.
Switch or the switch for reverse rotation, the switch for forward rotation
Switch contact or the reverse switch contact is closed.
While the emergency escape switch is pressed, the stop temperature
Emergency escape switch installed in parallel with the degree relay contact
An emergency escape means for closing a contact and connecting the contactor to rotate the drive motor; and an overload protection device for an excavator drive motor.