JP2013217070A - Control device for construction machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for a construction machine using an electric motor as a prime mover, for achieving a longer service life by preventing damage to a coil or etc. of the electric motor during operation at a high temperature.SOLUTION: The temperature of an electric motor 26 is detected by a temperature sensor 33. When the detected temperature of the electric motor is higher than a reference temperature, an output current to a solenoid 47a of a solenoid proportional valve 47 which operates a discharge flow controller 46 for the operation amount of an operation lever 22 is restricted. Thus, when the temperature of the electric motor 26 is higher, the load of the electric motor 26 is reduced to prevent damage to the electric motor 26 at a high temperature.

Description

  The present invention relates to a control device for preventing breakage of an electric motor due to a high temperature in a construction machine such as a hydraulic excavator using an electric motor as a power source.

  In construction machines such as a hydraulic excavator, there are a power source mounted on the upper swing body using an engine and a power source using an electric motor as described in Patent Document 1, for example.

JP 2003-105804 A

  When an engine is used as a power source for a construction machine, the engine may be damaged if a high load operation is performed to operate the front of a boom, an arm, or the like when the engine coolant is hot. For this reason, it is possible to set the engine speed to a low speed by the engine rotation command means such as a throttle lever, and to prevent the engine from becoming too hot.

  However, in the case of an electric hydraulic excavator using an electric motor instead of an engine as a prime mover and using a power source of a fixed frequency as a power source of the electric motor, when the electric motor is started, the electric motor immediately rotates at a rated speed. Rotate by number. When the electric motor driven at the rated frequency is operated in a high temperature state as described above, there is a possibility that the windings and the like may be damaged when the electric motor is at a high temperature when operating at a high load by a front operation or the like.

  In view of the above problems, the present invention controls a construction machine that can prevent damage to the windings of the electric motor during operation at a high temperature and extend its life in a construction machine using an electric motor as a prime mover. An object is to provide an apparatus.

The construction machine control device according to claim 1 is:
An electric motor that drives the hydraulic pump, a hydraulic actuator that is operated by hydraulic oil discharged from the hydraulic pump, a control valve that controls the direction and flow rate of hydraulic oil supplied to the hydraulic actuator, and an operation signal for the control valve Of a construction machine comprising: an operation device that generates an electric signal; an electromagnetic proportional valve that is switched and controlled by the electric signal to generate an operation hydraulic pressure of the control valve; and an electromagnetic proportional valve for controlling a discharge flow rate of the hydraulic pump. In the control device,
A temperature sensor for detecting the temperature of the electric motor;
When the temperature detected by the temperature sensor is higher than a preset reference temperature, the discharge current of the hydraulic pump is limited by limiting the output current to the solenoid of the electromagnetic proportional valve for discharge flow control with respect to the operation amount of the operating device. Operating signal limiting means.

The construction machine control device according to claim 2 is the construction machine control device according to claim 1,
When the detected temperature of the electric motor is higher than a reference temperature, the operation signal limiting means increases the upper limit of the output current to the solenoid of the electromagnetic proportional valve for discharge flow control with respect to the operation amount of the operating device as the detected temperature is higher The current value is set low.

The construction machine control device according to claim 3 is the construction machine control device according to claim 1 or 2,
When the detected temperature of the electric motor is higher than the reference temperature, the higher the detected temperature is, the longer the state in which the output current to the solenoid of the electromagnetic proportional valve for discharge flow control with respect to the operation amount of the operating device is limited is set. It further has time setting means.

The construction machine control device according to claim 4 is the construction machine control device according to any one of claims 1 to 3.
An alarm means for notifying that the output current to the solenoid of the solenoid valve for controlling the discharge flow rate is limited is further provided.

  According to the first aspect of the invention, when the detected temperature of the electric motor is high, the current to the solenoid of the hydraulic pump discharge flow rate control solenoid proportional valve with respect to the operation amount of the hydraulic actuator operating device is limited to a low value. When the temperature is high, the discharge flow rate of the hydraulic pump is kept low. As a result, when the electric motor is hot, the load on the electric motor is reduced. For this reason, damage to the windings of the electric motor due to a high load at a high temperature can be prevented, and the life can be extended.

  According to the invention of claim 2, when the temperature of the electric motor is higher than the reference temperature, the higher the detected temperature is, the more the current to the solenoid of the solenoid valve for controlling the hydraulic pump discharge flow rate with respect to the operation amount of the hydraulic actuator operating device. Since the upper limit current value is set low, better control corresponding to the temperature condition is performed in preventing the electric motor from being damaged.

  According to the third aspect of the present invention, when the temperature of the electric motor is higher than the reference temperature, the higher the detected temperature, the more the current to the solenoid of the solenoid valve for controlling the hydraulic pump discharge flow rate relative to the operation amount of the hydraulic actuator operating device. Since the time to limit to low is set long, better control corresponding to the temperature condition is performed in preventing the electric motor from being damaged.

  According to the invention of claim 4, since the alarm means for notifying that the current to the solenoid of the electromagnetic proportional valve for hydraulic pump discharge flow rate control with respect to the operation amount of the hydraulic actuator operating device is limited low, For example, when an operation target apparatus such as a boom or an arm operates at a low speed, the operator can know the reason for the low speed by the alarm means, and the operational reliability of the operator can be improved.

It is a side view which shows the hydraulic excavator which is an example of the construction machine to which this invention is applied. It is a top view which shows arrangement | positioning of the operating device in the driver's cab in the hydraulic shovel of FIG. FIG. 2 is a hydraulic electric circuit diagram illustrating an example of a control circuit of the hydraulic excavator in FIG. 1. It is a block diagram which shows one Embodiment of input-output relations, such as an operation lever of this invention, a controller, and an electromagnetic proportional valve. It is a functional block diagram which shows an example of the control apparatus of this embodiment. It is a graph which shows an example of the relationship between the temperature of the electric motor in the control apparatus of this embodiment, and the upper limit electric current value to the solenoid of the electromagnetic proportional valve for hydraulic pump discharge flow control. It is a graph which shows an example of the relationship between the temperature of the electric motor in the control apparatus of this embodiment, and the time which restrict | limits the electric current to the solenoid of the electromagnetic proportional valve for hydraulic pump discharge flow control. It is a flowchart which shows an example of the flow of a process in the control apparatus of this embodiment. In the control device of this embodiment, it is a time chart showing an example of an operation mode in a state in which the current to the solenoid of the hydraulic pump discharge flow rate control electromagnetic proportional valve is not limited. In the control device of this embodiment, it is a time chart showing an example of the operation mode in a state in which the current to the solenoid of the electromagnetic proportional valve for hydraulic pump discharge flow rate control is limited.

  FIG. 1 is a side view showing a hydraulic excavator as an example of a construction machine to which the present invention is applied. Reference numeral 1 denotes a lower traveling body. The lower traveling body 1 has drive wheels 3 that are driven by a traveling motor (not shown) made of a hydraulic motor attached to rear portions of left and right side frames 2 constituting a track frame. A driven wheel 4 is attached to the front portion of the frame 2 and a crawler belt 5 is hung around the driving wheel 3 and the driven wheel 4.

  Reference numeral 6 denotes an upper swing body installed on the lower traveling body 1 via a swing device 7. The turning device 7 has a turning motor (not shown) made of a hydraulic motor. An cab 9 and a power unit 10 are mounted on the upper swing body 6.

  Reference numeral 11 denotes a working device attached to the upper swing body. The working device 11 is pivotable in the vertical direction by a boom 13 attached to the upper swing body 6 by a boom cylinder 12 that is a hydraulic cylinder so as to be raised and lowered, and an arm cylinder 14 that is a hydraulic cylinder at the tip of the boom 13. An arm 15 attached to the arm 15 and a loader bucket 17 rotatably attached to the tip of the arm 15 by a bucket cylinder 16 made of a hydraulic cylinder.

  FIG. 2 is a plan view showing the arrangement of the hydraulic actuator operating device installed in the cab 9. In FIG. 2, 20 is an operator's seat, 21 and 22 are operating levers installed on the left and right sides of the seat 20, respectively, 23 and 24 are installed in front of the operator cab 9, and the left traveling of the lower traveling body 1 is performed. This is an operating lever for operating the motor and the right traveling motor. The operation lever 21 on the left side of the seat 20 rotates the arm 15 up and down by the arm cylinder 14 by operation in the front-rear direction, and turns the upper revolving body 6 left and right by the turning motor of the turning device 7 by operation in the left-right direction. It is. The operation lever 22 on the right side of the seat 20 causes the boom 13 to be lifted by the boom cylinder 12 by the operation in the front-rear direction, and the loader bucket 17 is excavated and discharged by the bucket cylinder 16 by the operation in the left-right direction. . The correspondence relationship between the operation directions of these operation levers 21 and 22 and the operation target device can be variously changed.

  FIG. 3 is a circuit diagram showing an electrohydraulic circuit for driving a hydraulic actuator of the hydraulic excavator. The power unit 10 shown in FIG. 1 drives a main hydraulic pump 27 and a pilot pump 28 by an electric motor 26. The electric motor 26 is driven by a power source having a fixed frequency. When this hydraulic excavator is used for excavation of ore, coal, or the like, power sources for driving the electric motor 26 are prepared at a plurality of locations on the excavation site, and the electric motor 26 is connected to the power source shown in FIG. They are connected via a cable 18.

  Reference numeral 12 denotes a boom cylinder as a representative example of the hydraulic actuator, and reference numeral 29 denotes a control valve of the boom cylinder 12. Reference numeral 30 denotes a controller. The controller 30 is a control valve for various actuators such as a control valve 29 (travel motor of the lower traveling body 1, swing motor of the swing device 7, boom cylinder 12, arm cylinder 14, bucket cylinder 16 and the like). Etc. are controlled. Reference numeral 22 denotes an operation lever for the boom cylinder 12 shown in FIG. 2, and the operation lever 22 is constituted by an electric lever using a potentiometer that generates an electric signal (voltage) corresponding to the operation amount. Similarly, the other operation levers 21, 23, and 24 shown in FIG. 2 are electric levers that generate an electric signal corresponding to the operation amount.

  31 and 32 are electromagnetic proportional valves for switching and controlling the control valve 29. The electromagnetic proportional valves 31 and 32 are configured so that the current generated by PWM control in the controller 30 according to the operation amount of the operation lever 22 is applied to the solenoids 31 a and 32 a, so that the opening of the electromagnetic proportional valves 31 and 32 has an opening corresponding to the current. Is something that opens. The pilot hydraulic pressure corresponding to the opening is applied to the operation chambers 29a and 29b of the control valve 29, the control valve 29 is switched, and the flow rate corresponding to the opening is supplied to the boom cylinder 12. Therefore, the load of the main hydraulic pump 27 changes according to the magnitude of the current supplied to the solenoids 31a, 32a of the electromagnetic proportional valves 31, 32, and the load of the electric motor 26 changes. Reference numeral 33 denotes a temperature sensor that detects the temperature of the electric motor 26, and preferably detects the temperature of the winding of the electric motor 26. A rotation sensor 34 detects the rotation of the electric motor 26.

  46 is a discharge flow rate control device of the main hydraulic pump 27, and this discharge flow rate control device 46 is constituted by a tilt angle control device. 47 is an electromagnetic proportional valve that operates the discharge flow rate control device 46 to control the discharge flow rate of the main hydraulic pump 27. The electromagnetic proportional valve 47 controls the pilot pressure applied from the pilot pump 28 to the discharge flow rate control device 46 by the magnitude of the current supplied from the controller 30 to the solenoid 47a. That is, the pilot current applied to the discharge flow rate control device 46 increases as the current flowing through the solenoid 47a increases, and the discharge flow rate of the main hydraulic pump 27 is increased. Reference numeral 48 denotes an alarm lamp. As will be described later, when the discharge flow rate of the main hydraulic pump 27 is limited on condition that the electric motor 26 is at a high temperature higher than the reference temperature, the operator is informed that the discharge flow rate is limited. It is to inform. As shown in FIG. 2, the alarm lamp 48 is installed in the cab 9.

  FIG. 4 is a block diagram showing an embodiment of the input / output relationship of the operation lever, controller, electromagnetic proportional valve and the like according to the present invention. As shown in FIG. 4, the output electric signals of the operation levers 21 to 24, the detection signal of the temperature sensor 33, and the detection signal of the rotation sensor 34 are input to the input side of the controller 30. On the output side of the controller 30, in addition to the electromagnetic proportional valves 31 and 32 for the boom 12 shown in FIG. 3, the electromagnetic proportional valves for rotation 36 and 37, the electromagnetic proportional valves for arms 38 and 39, and the electromagnetic proportional valve for buckets. 40, 41, electromagnetic proportional valves 42, 43 for forward / rearward movement of the left traveling motor, and electromagnetic proportional valves 44, 45 for forward / rearward movement of the right traveling motor are arranged. Each of these electromagnetic proportional valves is provided with a corresponding control valve (not shown). On the output side of the controller 3, an electromagnetic proportional valve 47 for discharge flow rate control shown in FIG.

  FIG. 5 is a functional block diagram showing an embodiment of the control device of the present invention, which is realized by the controller 30. In FIG. 5, reference numeral 50 denotes an operation signal limiting means for setting an upper limit current value IL which is the maximum value of the current to the solenoid 47a of the discharge flow control electromagnetic proportional valve 47 according to the temperature of the electric motor 26.

  FIG. 6 shows the upper limit current value IL of the current I applied to the solenoid 47a and the like via the solenoid drive circuit 52 controlled by the operation signal limiting means 50. In FIG. 6, the minimum temperature T (MIN) serving as a reference temperature for determining whether or not to perform load limitation is set to 120 ° C., for example, and the maximum temperature T (MAX) is set to 150 ° C., for example. Here, the minimum temperature T (MIN) is a temperature at which the upper limit current value IL is set to a constant high upper limit current value IL (MAX) below that temperature. As shown in FIG. 6, when the temperature of the electric motor 26 becomes equal to or higher than the minimum temperature T (MIN) at which load control is performed, the upper limit current value IL is set to a lower value as the motor temperature increases, and the maximum temperature T (MAX). This is zero. In addition, it is preferable that these temperatures T (MIN) and T (MAX) can be changed according to the usage mode of the construction machine.

  The time limit setting means 51 shown in FIG. 5 sets a time ta for limiting the current I to the solenoid 47a or the like when the temperature T of the electric motor 26 detected by the temperature sensor 33 is T> T (MIN). It is. FIG. 7 shows an example of the relationship between the detected temperature T of the electric motor 26 and the time limit ta set by the time limit setting means 51. As shown in FIG. 7, the time limit ta is set to a longer time as the temperature T of the electric motor 26 is higher. When the detected temperature T of the electric motor 26 is equal to or lower than the minimum temperature T (MIN), the time limit ta is 0 minute. Further, when the temperature of the electric motor 26 is equal to or higher than T (MAX), the longest time t (MAX) is set to 20 minutes, for example. It is preferable that the maximum time can be changed according to the outside air temperature, the working environment, and the like.

  FIG. 8 is a flowchart showing the flow of processing of the control device of this embodiment. First, in step 1, when the electric motor 26 is activated by turning on a key switch (not shown) provided in the cab of the rotary hydraulic excavator, the temperature sensor 33 is connected to the electric motor 26. The temperature T is detected. Further, in step 2, the controller 30 refers to whether or not the rotation sensor 34 has detected the rotation of the electric motor 26. If the rotation sensor 34 is rotating, the operation signal limiting means 50 determines the solenoid 47a from the temperature T of the electric motor. The upper limit current value IL is calculated, or the upper limit current value IL is read from the temperature-upper limit current value table (step 3). Here, if the temperature T of the electric motor 26 is equal to or lower than the minimum temperature T (MIN) of the reference temperature, the upper limit current value IL is not limited (IL (MAX) in FIG. 6). On the other hand, when the temperature T of the electric motor 26 is higher than the minimum temperature T (MIN) of the reference temperature, the higher the temperature, the lower the upper limit current value IL is set.

  Then, the operation signal limiting means 50 determines whether or not to limit the upper limit current value IL from the temperature T of the electric motor 26 detected by the temperature sensor 33 (step 4). If the temperature T of the electric motor 26 is equal to or lower than the minimum temperature T (MIN) of the reference temperature (T ≦ T (MIN)), the upper limit current value IL is not limited (IL (MAX) in FIG. 6). That is, when the operation levers 21 to 24 are operated, the operation is performed without limiting the current I to the solenoid 47a of the discharge flow rate control electromagnetic proportional valve 47 of the main hydraulic pump 27 (step 5).

  The operation mode when T ≦ T (MIN) is shown in the time chart of FIG. FIG. 9 shows that the current I to the solenoid 47a of the electromagnetic proportional valve 47 reaches the maximum value with respect to the maximum operation amount for raising and lowering the boom of the operation lever 22. In FIG. 9, the boom operation lever input signal displayed in the third row indicates a change in the DC voltage applied to the controller 30 by the operation of the operation lever 22, for example, the median is 3 V and the maximum is 4. 5V, the minimum is 0.5V. When the voltage to the controller 30 of the boom operation lever 22 is 4.5V or 0.5V, the controller 30 outputs IL (MAX) as the solenoid valve output signal (current to the solenoid 47a). The output signal (current to solenoid 47a) is zero.

  On the other hand, when T> T (MIN) and the upper limit current value IL is limited, control is performed so that the current to the solenoid 47a does not exceed the upper limit current value IL (IL <IL (MAX)). An alarm lamp 48, which is an alarm means, is turned on to inform the operator that the output is being restricted (step 6). The operation mode in a state where the output is restricted is shown in the time chart of FIG. As can be seen from FIG. 10, even when the operation lever 22 is operated to the maximum operation amount, the output current to the solenoid 47a in the state where the output is limited is limited to a value smaller than the upper limit current value IL (MAX). For this reason, even if the operation lever 22 is operated to the maximum, the opening area of the flow path of the electromagnetic proportional valve 47 is limited to be smaller than the maximum opening degree. For this reason, even if the operation lever 22 is operated to the maximum operation amount, the discharge flow rate of the main hydraulic pump 27 is limited, and the load on the electric motor 26 is reduced.

  Simultaneously with the start of the control with the output being limited (IL <IL (MAX)), the time limit setting means 51 shown in FIG. 5 has the correlation shown in FIG. The corresponding time limit ta is calculated, or the time limit ta is read from the temperature-time limit ta table (step 7). Then, the operation is continued with the output restricted (steps 8 and 9). When such an operating state passes the time limit ta, the alarm lamp 48 is turned off (step 10). Then, the process shifts to a control mode without output restriction (step 5).

  According to this embodiment, when the temperature T of the electric motor 26 is detected and the detected temperature is higher than a preset reference temperature T (MIN), the output electric signal corresponding to the operation amount of the operation levers 21 to 24, that is, the discharge Since the current to the solenoid 47a of the electromagnetic proportional valve 47 that controls the flow control device 46 is limited to a low value, the discharge flow rate of the main hydraulic pump 27 is suppressed when the temperature T of the electric motor 26 is low. . As a result, when the temperature T of the electric motor 26 is high, the load on the electric motor 26 decreases. For this reason, it is possible to prevent the winding of the electric motor 26 from being damaged due to a high load at a high temperature and to prolong the service life.

  Further, in this embodiment, as the temperature T of the electric motor 26 is higher, the upper limit current value IL to the solenoid 47a of the discharge flow rate control electromagnetic proportional valve 47 with respect to the operation amount of the operation levers 21 to 24 is set lower. In preventing the electric motor from being damaged, better control corresponding to the temperature condition is performed.

  In this embodiment, the higher the temperature T of the electric motor 26, the lower the time limit for lowering the upper limit current value IL to the solenoid 47a of the discharge flow control electromagnetic proportional valve 47 with respect to the operation amount of the operation levers 21 to 24. Since ta is set longer, better control corresponding to the temperature condition is performed in preventing the electric motor 26 from being damaged.

  Further, since an alarm means such as an alarm lamp 48 for notifying that the output electric signal with respect to the operation amount of the operation levers 21 to 24 is kept low is provided, the operation object is operated when the operator operates the operation levers 21 to 24. When the devices (the boom 12, the arm 15, the bucket 17, etc.) operate at a low speed, the operator can know the reason, and the operational reliability of the operator can be enhanced.

  In the embodiment shown in FIG. 5, the upper limit current value IL is set to a fixed value depending on the temperature of the electric motor 26 detected first during the limit time ta. It may be increased as the detected temperature T of the electric motor 26 decreases.

  In the above embodiment, the construction machine is a hydraulic excavator using a loader bucket. However, the present invention can also be applied to a hydraulic excavator using a backhoe bucket and other construction machines other than the hydraulic excavator. . In addition to the lamp, an alarm device, a display device using a screen, or the like can be used as alarm means for notifying the operation state in the output restricted state.

  A two-stage pilot valve configuration in which a hydraulically operated pilot valve is interposed between the electromagnetic proportional valve 47 and the discharge flow rate control device 46 may be adopted. Further, only the operation lever is shown as the operation device for the hydraulic actuator, but the present invention can also be applied to the case where the pedal is used as the operation device. In addition, various changes and additions can be made without departing from the scope of the present invention.

  1: lower traveling body, 2: side frame, 3: driving wheel, 4: driven wheel, 5: crawler track, 6: upper turning body, 7: turning device, 9: cab, 10: power unit, 11: working device, 12: boom cylinder, 13: boom, 14: arm cylinder, 15: arm, 16: bucket cylinder, 17: loader bucket, 18: power cable, 21-24: operation lever, 26: electric motor, 27: main hydraulic pump , 28: pilot pump, 29: control valve, 30: controller, 31, 32, 36 to 45: proportional solenoid valve, 31a, 32a: solenoid, 33: temperature sensor, 34: rotation sensor, 46: discharge flow rate control device, 47: Solenoid proportional valve for discharge flow rate control, 47a: Solenoid, 48: Alarm lamp

Claims (4)

An electric motor that drives the hydraulic pump, a hydraulic actuator that is operated by hydraulic oil discharged from the hydraulic pump, a control valve that controls the direction and flow rate of hydraulic oil supplied to the hydraulic actuator, and an operation signal for the control valve Of a construction machine comprising: an operation device that generates an electric signal; an electromagnetic proportional valve that is switched and controlled by the electric signal to generate an operation hydraulic pressure of the control valve; and an electromagnetic proportional valve for controlling a discharge flow rate of the hydraulic pump. In the control device,
A temperature sensor for detecting the temperature of the electric motor;
When the temperature detected by the temperature sensor is higher than a preset reference temperature, the discharge current of the hydraulic pump is limited by limiting the output current to the solenoid of the electromagnetic proportional valve for discharge flow control with respect to the operation amount of the operating device. And a control device for the construction machine, comprising: The control device for a construction machine according to claim 1,
When the detected temperature of the electric motor is higher than a reference temperature, the operation signal limiting means increases the upper limit of the output current to the solenoid of the electromagnetic proportional valve for discharge flow control with respect to the operation amount of the operating device as the detected temperature is higher A control device for a construction machine, wherein the current value is set low. The construction machine control device according to claim 1 or 2,
When the detected temperature of the electric motor is higher than the reference temperature, the higher the detected temperature is, the longer the state in which the output current to the solenoid of the electromagnetic proportional valve for discharge flow control with respect to the operation amount of the operating device is limited is set. A control device for a construction machine, further comprising time setting means. The construction machine control device according to any one of claims 1 to 3,
The construction machine control device further comprising alarm means for notifying that the output current to the solenoid of the solenoid valve for controlling the discharge flow rate is limited.

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