JP2005189211A - Angle detector for working machinery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an angle detector, capable of prolonging the life time of a vibrating motor, provided to reduce hysteresis and the rotational torque of the angle detector. <P>SOLUTION: In this angle detector provided with a potentiometer 22 provided in a casing 21 forming an outer shell, and an oscillator 24 attached to an shaft 23 of the potentiometer 22, and for detecting a ground angle of an angle to a horizontal face, the vibration motor 25 is provided inside the casing 21; the vibration motor 25 is driven only during operations of a tower turning-up and -down winch 8 and a jib turning-up and -down winch 9 for turning up and down a tower boom 2 and a tower jib 3, that is, only when the hysteresis in the angle detector is required to be removed; and the life time of the vibration motor 25 is prolonged thereby. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an angle detection device for a work machine that detects a rotation angle of a rotatable work device provided in various work machines such as a crane and a hydraulic excavator.

  Work machines, such as cranes, are provided with an overload prevention device for preventing overturning due to a suspended load. In this overload prevention device, the load of a suspended load suspended from a boom as a working device is set to a limit load (allowable suspended load for preventing a fall) set in advance for each boom angle (working radius). It is a safety device that monitors to ensure that it does not exceed the limit. When the limit load is exceeded, an alarm is issued, and the operation of the boom is limited so that the working radius does not increase any further. And in order to detect the rotation angle of the boom for this overload prevention device, an angle detector is provided near the rotation part of the boom. This angle detector includes a rotation sensor composed of a potentiometer or an encoder provided in a casing forming an outer shell, and a pendulum attached to the shaft of the rotation sensor. Then, when the housing is rotated with the rotation of the boom, the pendulum is rotated so as to maintain the gravity direction, that is, the vertical direction, and the rotation sensor shaft rotates accordingly, and the angle of the boom with respect to the horizontal plane The ground angle is detected.

  The rotation sensor composed of the potentiometer or encoder of the angle detector does not need to take into consideration the fluctuation of the output voltage accompanying the change in temperature, that is, the temperature characteristic, as compared with the non-contact type rotation sensor having other magnetoresistive elements. In addition, the degree of deviation of the output voltage with respect to the rotation angle, that is, linearity is excellent. Therefore, it is suitable for installation in a working machine such as a crane or a hydraulic excavator that is required to work in an environment with a large temperature change or to detect the angle of the boom or arm with high accuracy.

However, the rotation sensor composed of a potentiometer or an encoder generates static friction due to its structure, and an error is caused in the detection angle due to hysteresis due to the static friction. As a technique for reducing this error, the present applicant has previously filed an angle detection device in which a vibration motor is incorporated and the rotational torque of the potentiometer is reduced to reduce hysteresis. (See Patent Document 1.)
JP 2002-107143 A

  In the technology described in the above publication, a vibration motor is provided in a housing in which a potentiometer is housed, and the vibration motor is operated at the time of detecting an angle. It is a fraction of the time, that is, a conventional fraction. Thus, an inexpensive angle detector is provided while improving accuracy.

However, the technique of the above publication has room for improvement as follows.
In other words, as the vibration motor, it is advantageous from the viewpoint of price and size to use a vibration motor that is used for notification of incoming calls of a mobile phone, but the small vibration used in this mobile phone or the like. Since the motor has special characteristics (non-continuous use), it has not been constructed so that it can be used for continuous use in the first place, and it has been insufficient in terms of life when continuously driven.

  An object of the present invention is to provide an angle detection device that can extend the life of a motor even if it is an angle detector using a vibration motor having a limited life in continuous driving.

  In order to achieve the above-described object, an angle detection device for a work machine according to the present invention includes a rotatable work device, operation means for operating the work device, and operation state detection for detecting an operation state of the work device. And an angle detection unit that detects a rotation angle of the working device. In the invention according to claim 1, the angle detection unit includes a rotation sensor and a vibration generation unit. And a drive control means for controlling the drive of the vibration generating means based on the operation state of the working device detected by the operation state detection means.

  According to a second aspect of the present invention, the drive control means outputs a pulse signal for a predetermined time when the operation state detection means detects the start of the operation of the actuator, and then intermittently continues during the operation. A pulse signal is output, and when the operation is completed, the pulse signal is stopped after a predetermined time has elapsed.

  According to a third aspect of the present invention, the angle detecting means is configured to detect a ground angle by providing a pendulum in a rotation sensor, and the vibration generating means is provided in the pendulum.

  As a result, the vibration motor is driven only when the angle of the actuator in which the angle detector is installed is changing, and the vibration motor is built in the pendulum. It is possible to eliminate hysteresis and extend the life time of the vibration motor, thereby extending the life time of the working machine angle detection device when the vibration motor is used for the angle detector. .

  Further, since the motor is driven for a predetermined time even when the actuator is not operated, hysteresis does not remain.

  According to the first aspect of the present invention, the vibration motor is driven only during the period when the actuator of the work machine on which the angle detector is installed is operated, that is, when the hysteresis of the angle detector needs to be removed. Can be extended.

  According to the invention of claim 2, by driving the vibration motor with intermittent pulses, it is possible to achieve the minimum rotational speed necessary for removing hysteresis, and further extending the life of the vibration motor. Can do.

  Further, according to the invention of claim 3, since the vibration motor is built in the pendulum, it becomes possible to achieve the minimum rotation speed necessary for removing hysteresis with a small excitation force, and the life of the vibration motor is further improved. Can be extended.

Embodiments of the ground angle detection device of the present invention will be described below with reference to the drawings.
FIG. 1 is a side view showing a tower crane, which is an example of a work machine provided with an angle detection device for a work machine according to the present invention.

  The tower crane shown in FIG. 1 is provided with a main body 1 including a traveling body and a driver's cab, a tower boom 2 (working device) that is rotatably provided on the main body 1, and a pivot at the upper end of the tower boom 2. A tower jib 3 (working device), a hoisting rope 5 suspended from the tip of the tower jib 3, a hook 4 provided at the lower end of the hoisting rope 5 and used for lifting and lowering a load, and provided on the main body 1. The tower boom 2, the tower hoisting rope 6 for turning the tower jib 3 up and down, the tower hoisting winch 8 for taking up and feeding the jib hoisting rope 7, and the jib hoisting winch 9 are provided. Further, a ground angle detector for detecting a ground angle with respect to a horizontal plane, that is, a tower boom angle detector 10, is provided near the lower end of the tower boom 2, and a tower jib angle that is also a ground angle detector is disposed near the lower end of the tower jib 3. A detector 11 is provided. A load detector 12 for detecting the weight of the load suspended and hung by the hook 4 is provided at the end of the hoisting rope (not shown) of the tower boom 2. The tower boom angle detector 10 and the tower jib angle detector 11 have a structure as shown in FIG.

  Further, an operation lever (not shown) for operating the tower hoisting winch 8 and the jib hoisting winch 9 is provided in the cab, and an operation state detecting means 35 for detecting the operating state of the tower hoisting winch 8 and the jib hoisting winch 9 is provided. , 36 are provided. The operation state detection means 35 and 36 are a switch (limit switch or the like) that is switched by the operation of the operation lever described above, and a sensor that detects an operation command (for example, a hydraulic pilot signal) from the operation lever to the hoisting winches 8 and 9. A sensor that directly detects the operation (rotation) of the hoisting winches 8, 9 is used.

  Further, in the main body 1, an overload prevention device that executes arithmetic processing for preventing the tower crane from falling based on signals output from the tower boom angle detector 10, the tower jib angle detector 11, and the load detector 12. The control apparatus 13 which comprises is provided.

  The tower crane control device 13 shown in FIG. 1 includes an angle signal output from the tower boom angle detector 10 as the tower boom 2 rotates, and a tower jib angle detector 11 as the tower jib 3 rotates. Based on the output angle signal, the working radius of the tower crane is calculated, and the limit load allowed by the working radius, that is, the limit load that is a limit value for preventing overturning is calculated. Then, the load actually applied to the hook 4 is obtained from the load signal output from the load detector 12, and the actual load is compared with the limit load described above. As a result of this comparison, for example, when the actual load is about to exceed the limit load, an alarm signal that activates the alarm is output, or a process that automatically controls the working radius so that it does not become any larger is performed. .

  FIG. 2 is a view showing the tower boom angle detector 10 and the tower jib angle detector 11 which are the above-described ground angle detectors of the present invention. FIG. 2A is a front view showing a state in which the front side portion is removed, and FIG. FIG. Since the tower boom angle detector 10 and the tower jib angle detector 11 have the same structure, the tower boom angle detector 10 will be described. The angle detector 10 includes a casing 21 that forms an outer shell, a rotation sensor provided in the casing 21, for example, a potentiometer 22, and a pendulum 24 that is attached to a shaft 23 of the potentiometer 22. The pendulum 24 is provided with vibration generating means for generating vibration to be applied to the potentiometer 22, for example, a vibration motor 25. The vibration motor 25 can be provided, for example, by forming a recess in the pendulum 24 and storing the recess in the recess, or by incorporating the pendulum 24 in advance.

  The tower boom angle detector 10 is rotated so that the pendulum 24 maintains the gravitational direction, that is, the vertical direction when the casing 21 is integrally rotated with the rotation of the tower boom 2 shown in FIG. As a result, the shaft 23 of the potentiometer 22 rotates to detect the ground angle, which is the angle of the tower boom 2 with respect to the horizontal plane.

  3 is a block diagram showing a configuration of an angle detection device including a drive control device that controls driving of the vibration motor 25 including the angle detector, and FIG. 4 is a microcontroller included in the drive control device shown in FIG. It is an output time chart which shows the process sequence implemented by.

  As shown in FIG. 3, the angle detection device drives a power source 31 of the potentiometer 22, an A / D converter 32 that converts an angle signal output from the potentiometer 22, that is, an analog signal into a digital signal, and a vibration motor 25. A vibration motor driving means 33 that outputs a pulse signal and a control signal that performs a predetermined calculation in accordance with a signal input from the A / D converter 32 and operates the vibration motor driving means 33 as appropriate, or a vibration motor The controller 30 includes a microcontroller 34 that outputs a control signal for stopping the driving unit 33, and an operation state detection unit 35 (36) connected to the microcontroller 34. The operation state detection unit 35 (36) The tower boom 2 (tower jib 3) on which the angle detector 10 (11) is installed is moved up and down. -When detecting that the hoisting winch 8, (jib hoisting winch 9) is operated, the microcontroller 34 outputs a control signal for operating the vibration motor driving means 33, and the vibration motor driving means 33 detects the operation state. A drive pulse as described below is output in accordance with the operation state detected by the means 35 (36), and the vibration motor 25 is driven.

  FIG. 4 is a diagram showing an output time chart of the driving means 33 processed by a microcontroller or the like included in the control device shown in FIG. When the operation state detecting means 35 (36) detects that the operation of the tower hoisting winch 8 (tower jib hoisting winch 9) is activated, the driving means 33 is driven by the vibration motor 25 as shown by the motor drive output (a) in the figure. A motor start pulse P1 having a predetermined time width (T1) so as to achieve a predetermined rotation is output. If the operation of the tower hoisting inch 8 (tower jib hoisting winch 9) continues even after the start pulse ends, the driving means 33 switches the output to the intermittent pulse P2. The intermittent pulse P2 is set to a pulse (a time width T3 in the period T2) that provides a minimum rotation speed that allows the vibration motor 25 to continue to rotate and to remove hysteresis.

  Further, when detecting that the operation of the tower hoisting inch 8 (tower jib hoisting winch 9) is stopped, the driving means 33 stops the intermittent pulse P2 after a predetermined time (T4a) has elapsed in order to remove the residual hysteresis.

  As shown in the motor drive output (b) in the figure, instead of stopping the intermittent pulse P2 after the predetermined time (T4a) has elapsed, it is detected that the operation of the tower hoisting inch 8 has stopped, and the intermittent pulse P2 is detected. May be stopped, and a pulse P3 having a predetermined time width (T4b) may be output, thereby further improving the responsiveness.

  In the above-described embodiment, the case of the tower boom angle detector 10 that detects the angle of the tower boom 2 has been described. However, in the case of the tower jib angle detector 11 that detects the angle of the tower jib 3, the tower jib 3 is a tower. Due to the crane structure, the angle changes not only by the individual operation but also by the hoisting operation of the tower boom 2, so that when the tower hoisting winch 8 or the jib hoisting winch 9 is operated, the above control is performed. Like that.

  In one embodiment of the angle detection device configured as described above, the tower boom 2 and the tower jib 3 in which the angle detector is installed are undulated in addition to the effect described in the above-mentioned Patent Document 1 filed by the applicant. By operating the vibration motor 25 and operating the vibration motor 25 with intermittent pulses while operating the tower hoisting winch 8 and the jib hoisting winch 9, that is, when hysteresis removal of the angle detector is necessary. In addition, since it becomes possible to achieve the minimum rotational speed necessary for removing hysteresis, the life of the vibration motor can be greatly extended. In addition, since a small vibration motor can be used with a longer life, it is possible to use a small vibration motor that is used for notification of incoming calls of mobile phones, and a low-cost angle detection device can be realized.

  Further, since the vibration motor is attached to the pendulum, it is possible to achieve the minimum rotation speed necessary for removing hysteresis with a small excitation force, and the life of the vibration motor can be further improved.

It is a side view of the tower crane which shows an example of the working machine provided with the angle detection apparatus of this invention. It is a figure which shows one Embodiment of a ground angle detector, (a) is a front view which shows the state which removed the front side part, (b) is a sectional side view. It is a block diagram which shows one Embodiment of the angle detection apparatus containing the ground angle detector shown in FIG. It is a figure which shows the output time chart of the drive means processed with the microcontroller etc. which are contained in the control apparatus shown in FIG.

Explanation of symbols

1 Body 2 Tower boom (working device)
3 Tower jib (work equipment)
6 Tower hoisting rope 7 Jib hoisting rope 8 Tower hoisting winch 9 Jib hoisting winch 10 Tower boom angle detector 11 Tower jib angle detector 21 Housing 22 Potentiometer 23 Shaft 24 Pendulum 25 Vibration motor 30 Controller 31 Power supply 32 A / D converter 33 Vibration motor drive means 34 Microcontroller 35 Operation state detection means (tower boom)
36 Operation state detection means (Tower Jib)

Claims (3)

A rotatable working device;
Operating means for operating the working device;
An operation state detecting means for detecting an operation state of the work device;
Used in a working machine provided with an angle detection means for detecting the rotation angle of the working device,
The angle detection means includes a rotation sensor and vibration generation means,
An angle detection device for a work machine, comprising: drive control means for controlling drive of the vibration generating means based on an operation state of the work device detected by the operation state detection means.     The drive control means outputs a pulse signal for a predetermined time when the operation state detection means detects the start of the operation of the actuator, and then outputs an intermittent pulse signal while the operation is continued, and when the operation ends, the drive control means 2. The angle detection device for a work machine according to claim 1, wherein the pulse signal is stopped after a lapse of time. 3. The work machine according to claim 1, wherein the angle detection unit has a configuration in which a rotation sensor is provided with a pendulum to detect a ground angle, and the vibration generation unit is provided in the pendulum. Angle detection device.

Images