JP2011117316A - Control device of construction machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device of a construction machine capable of preventing damage of an electric motor in operation at a low temperature in the construction machine using the electric motor as a power source. <P>SOLUTION: A temperature of the electric motor 26 is detected by a temperature sensor 33. The output current to solenoids 31a and 32a of electromagnetic proportional valves 31 and 32 with respect to the manipulated variable of an operation lever 22 is restricted when the detected temperature of the electric motor is lower than a reference temperature. Thus, the load of the electric motor 26 is reduced when the temperature of the electric motor 26 is low, and damage of the electric motor 26 at the low temperature can be prevented. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a control device for preventing breakage of an electric motor due to low 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 the engine is used as a power source for construction machinery, the engine may be damaged when the engine is operated at a high load by a front operation or the like if the engine is cold due to the winter season or the like. For this reason, when the temperature is low, the engine speed is set to a low speed by a rotational speed command means such as a throttle lever, and the engine is started and warmed up.

  On the other hand, in the case of a construction machine that uses an electric motor instead of an engine as a power source, when the electric motor is powered using a fixed frequency power source, the electric motor immediately rotates at the rated speed when the electric motor is started. To do. If the electric motor driven at the rated frequency is started at a low temperature in this way, it is likely to be a high-load operation due to a front operation or the like, and the electric motor may be damaged. In particular, since the toughness of the shaft of the electric motor decreases at a low temperature, when the electric motor is driven at a rated rotational speed with a high load at a low temperature, the shaft may be damaged by a twisting force acting on the shaft.

  In view of the above problems, an object of the present invention is to provide a construction machine control device capable of preventing the electric motor from being damaged during operation at a low temperature in a construction machine using an electric motor as a power source.

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 A control device for a construction machine comprising: an operation lever that generates an electric signal; and an electromagnetic proportional valve that is controlled by the electric signal to generate an operation hydraulic pressure of the control valve.
A temperature sensor for detecting the temperature of the electric motor;
An operation signal for limiting the flow rate of hydraulic fluid in the control valve by limiting the output current to the solenoid of the electromagnetic proportional valve with respect to the operation amount of the operation lever when the temperature detected by the temperature sensor is lower than a preset reference temperature. And a limiting means.

The construction machine control device according to claim 2 is the construction machine control device according to claim 1,
The operation signal limiting means sets the upper limit current value of the output current to the solenoid of the electromagnetic proportional valve with respect to the operation amount of the operation lever as the detected temperature of the electric motor is lower.

The construction machine control device according to claim 3 is the construction machine control device according to claim 1 or 2,
It further comprises time limit setting means for setting a long state in which the output current to the solenoid of the electromagnetic proportional valve with respect to the operation amount of the operation lever is limited.

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 electromagnetic proportional valve is in a limited state is further provided.

  According to the first aspect of the present invention, when the detected temperature of the electric motor is low, the current to the solenoid of the solenoid valve for controlling the control valve with respect to the operation amount of the operation lever is limited to a low value. When the pressure is low, the flow rate of hydraulic fluid flowing through the control valve is kept low. As a result, when the electric motor is at a low temperature, the load on the electric motor is reduced. For this reason, it is possible to prevent the electric motor from being damaged by a high load at a low temperature.

  According to the invention of claim 2, the lower the temperature of the electric motor, the lower the upper limit current value is set for the current to the solenoid of the electromagnetic proportional valve relative to the operation amount of the operation lever. Better control corresponding to the temperature situation is performed.

  According to the third aspect of the invention, the lower the temperature of the electric motor, the longer the time for limiting the current to the solenoid of the electromagnetic proportional valve with respect to the operation amount of the operation lever is set longer, thus preventing the electric motor from being damaged. Above, better control corresponding to the temperature situation is performed.

  According to the invention of claim 4, since the alarm means for notifying that the current to the solenoid of the electromagnetic proportional valve with respect to the operation amount of the operation lever is limited to be low is provided, for example, operation of a boom, an arm, etc. When the target device 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 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 an electromagnetic proportional valve. 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 an electromagnetic proportional valve. It is a flowchart which shows an example of the flow of a process in the control apparatus of this embodiment. It is a time chart which shows an example of the operation mode in the state which does not restrict | limit the electric current to the solenoid of an electromagnetic proportional valve in the control apparatus of this embodiment. It is a time chart which shows an example of the operation mode in the state which restricted the electric current to the solenoid of an electromagnetic proportional valve in the control apparatus of this embodiment. It is a functional block diagram which shows other embodiment of the control apparatus of this invention.

  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 operating devices 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 operation direction of these operation levers 21 and 22 and the operation target device can be variously changed.

  FIG. 3 is an electrohydraulic circuit diagram showing an electrohydraulic circuit for driving the hydraulic actuator of the 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. 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. In addition, when this hydraulic excavator is used for excavation of ore or coal, 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 shown in FIG. It is connected via a power cable 18 shown.

  Reference numeral 30 denotes a controller for controlling control valves for various actuators such as the control valve 29 (travel motor for the lower traveling body 1, swing motor for the swing device 7, boom cylinder 12, arm cylinder 14, bucket cylinder 16 and the like). 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 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 reference numeral 34 denotes a rotation sensor that detects the rotation of the electric motor 26.

  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, the electromagnetic proportional valves for rotation 36 and 37, the electromagnetic proportional valves for arms 38 and 39, the electromagnetic proportional valves for buckets 40 and 41, the left side Proportional electromagnetic proportional valves 42 and 43 for the traveling motor, and electromagnetic proportional valves 44 and 45 for forward and backward movement of the right traveling motor are arranged. Each of these electromagnetic proportional valves is provided with a corresponding control valve (not shown). As will be described later, 46 is an alarm lamp provided as an alarm means for informing the operator of the state when the electric motor 26 is started in a low temperature state.

  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 upper limit current value IL which is the maximum value of the current to the solenoids 31a and 32a of the electromagnetic proportional valves 31 and 32 (the same applies to the other electromagnetic proportional valves 36 to 45) according to the temperature of the electric motor 26. Is an operation signal limiting means for setting.

  FIG. 6 shows the upper limit current value IL of the current I applied to the solenoids 31a, 32a, etc. via the solenoid drive circuit 52 controlled by the operation signal limiting means 50. In FIG. 6, the minimum temperature T (MIN) is set to, for example, −20 ° C., and the maximum temperature T (MAX) is set to, for example, 0 ° C. The maximum temperature T (MAX) is a reference temperature for determining whether or not to limit the load on the electric motor 26. The minimum temperature T (MIN) is a temperature at which the upper limit current value IL is set to a certain low current value IL (MIN) below that temperature. In addition, it is preferable that these temperatures T (MAX) and T (MIN) can be changed depending on the usage mode of the construction machine.

  The time limit setting means 51 sets a time ta for limiting the current I to the solenoids 31a, 32a, etc. when the temperature T of the electric motor 26 detected by the temperature sensor 33 is T <T (MAX). is there. 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 lower. When the detected temperature T of the electric motor 26 is equal to or lower than the minimum temperature T (MIN), the maximum time t (MAX) of the time limit ta is set. The longest time t (MAX) is, for example, 30 minutes.

  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 started by turning on a key switch provided in the cab of the hydraulic excavator, the temperature sensor 33 detects the temperature T of the electric motor 26. 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 whether the operation signal limiting means 50 is a solenoid 31a from the temperature T of the electric motor. , 32a is calculated (step 3). Here, if the temperature T of the electric motor 26 is equal to or higher than the maximum temperature T (MAX) of the set 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 lower than the maximum temperature T (MAX) of the set temperature, the lower 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 higher than the maximum temperature T (MAX) of the set temperature (T ≧ T (MAX)), the upper limit current value IL is not limited (IL (MAX) in FIG. 6). That is, the operation is performed in a manner that does not limit the current I to the solenoid with respect to the operation amount of the operation levers 21 to 24 (step 5).

  FIG. 9 shows an operation mode when T ≧ T (MAX). FIG. 9 shows that the current I to the solenoids 31a and 32a of the electromagnetic proportional valves 31 and 32 reaches the maximum value with respect to the maximum operation amount of 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. If the voltage to the controller 30 of the boom operation lever 22 is 4.5 V or 0.5 V, the controller 30 outputs an IL (MAX) solenoid valve output signal (current to the solenoids 31a and 32a). The solenoid valve output signal (current to the solenoids 31a and 32a) becomes zero.

  On the other hand, when T <T (MAX) and the upper limit current value IL is limited, control is performed so that the current to the solenoids 31a and 32a does not exceed the upper limit current value IL (IL <IL (MAX)). And the alarm lamp 46, which is an alarm means, is lit to inform the operator that the output is being restricted (step 6). FIG. 10 shows an operation mode in a state where the output is restricted. 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 solenoids 31a and 32a in the state where the output is limited is limited to a value smaller than the upper limit current value IL (MAX). The For this reason, even if the operation lever 22 is operated to the maximum, the flow area of the electromagnetic proportional valves 31 and 32 is restricted to have an opening area smaller than the maximum opening degree. For this reason, even if the operation lever 22 is operated to the maximum operation amount, the hydraulic oil flow rate in the control valve 29 is kept low, so that 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 control in the state where the output is limited (IL <IL (MAX)), the time limit setting means 51 has the correlation shown in FIG. 7 and the time limit corresponding to the temperature T of the electric motor 26. ta is calculated (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 46 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 lower than a preset temperature T (MAX), an output electric signal corresponding to the operation amount of the operation levers 21 to 24, that is, Since the current to the solenoids of the electromagnetic proportional valves 31, 32, 36 to 45 for controlling the control valve is limited to a low value, the hydraulic oil flowing through the control valve when the temperature T of the electric motor 26 is low. The flow rate is suppressed. As a result, the discharge flow rate of the main hydraulic pump 27 is limited, and when the temperature T of the electric motor 26 is low, the load on the electric motor 26 decreases. For this reason, the electric motor 26 can be prevented from being damaged by a high load at a low temperature.

  Further, in this embodiment, the lower the temperature T of the electric motor 26, the lower the upper limit current value IL to the solenoid of the electromagnetic proportional valves 31, 32, 36 to 45 with respect to the operation amount of the operation levers 21 to 24 is set. Therefore, in preventing the electric motor from being damaged, better control corresponding to the temperature condition is performed.

  In this embodiment, the lower the temperature T of the electric motor 26, the lower the upper limit current value IL to the solenoids of the electromagnetic proportional valves 31, 32, 36 to 45 with respect to the operation amount of the operation levers 21 to 24. Since the time 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 46 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 is performed when the operator operates the operation levers 21 to 24. When the target device (boom 12, arm 15, bucket 17, etc.) operates at a low speed, the operator can know the reason, and the operational reliability of the operator can be improved.

  FIG. 11 is a functional block diagram showing another embodiment of the control device of the present invention. In this embodiment, the temperature T detected by the temperature sensor 33 of the electric motor 26 shown in FIG. 7 is compared with a preset reference temperature T (MAX), and electromagnetic waves are maintained while T <T (MAX). The operation in the load reduction state in which the maximum value of the current to the solenoids of the proportional valves 31, 32, 36 to 45 is suppressed is continued, an alarm is issued by the alarm lamp 46, and when T ≧ T (MAX), the normal load The operation is performed without any restrictions, and the alarm generation is stopped. By performing such control, more suitable time control corresponding to the temperature of the electric motor 26 can be performed.

  In the embodiment shown in FIGS. 5 and 11, in the operation within the time limit ta, the upper limit current value IL is set to a fixed value depending on the temperature of the electric motor 26 detected first. The current value IL may be increased as the detected temperature T of the electric motor 26 increases.

  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 valves 31 and 32 and the control valve 29 may be employed. With such a two-stage configuration, the distance between the control valve and the hydraulic pilot valve can be shortened, the length of the hydraulic pilot circuit can be shortened, and the pilot oil flow in the hydraulic pilot circuit can be reduced. Can solve the problem of response delay.

  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: electromagnetic proportional valve, 31a, 32a: solenoid, 33: temperature sensor, 34: rotation sensor, 46: 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 A control device for a construction machine comprising: an operation lever that generates an electric signal; and an electromagnetic proportional valve that is controlled by the electric signal to generate an operation hydraulic pressure of the control valve.
A temperature sensor for detecting the temperature of the electric motor;
An operation signal for limiting the flow rate of hydraulic fluid in the control valve by limiting the output current to the solenoid of the electromagnetic proportional valve with respect to the operation amount of the operation lever when the temperature detected by the temperature sensor is lower than a preset reference temperature. A control device for a construction machine, comprising: a limiting unit. The control device for a construction machine according to claim 1,
The operation signal limiting means sets the upper limit current value of the output current to the solenoid of the electromagnetic proportional valve relative to the operation amount of the operation lever as the detected temperature of the electric motor is lower. Control device. The construction machine control device according to claim 1 or 2,
A construction machine control device, further comprising time limit setting means for setting a state in which an output current to the solenoid of the electromagnetic proportional valve is limited with respect to an operation amount of the operation lever. The construction machine control device according to any one of claims 1 to 3,
A construction machine control device further comprising alarm means for notifying that the output current to the solenoid of the electromagnetic proportional valve is in a limited state.

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