Traversing hoists – With haul-in line
Patent
1991-11-25
1993-10-12
Mitchell, David M.
Traversing hoists
With haul-in line
212245, B66C 1350
Patent
active
052517683
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND TECHNOLOGY
The present invention relates to a method and device for braking rotation of an upper rotary body of a construction machine, such as crane, without swinging a lifted load, and also relates to a device for calculating the angle of inclination of the upper rotary body positioned at a given angle of rotation.
In construction machines such as crane equipped with a rotatable boom as upper rotary body, it is important to brake and stop rotation of the upper rotary body without swinging a lifted load. However, the conventional way of stopping rotation of an upper rotary body depends on manual operations by skilled operators. Accordingly, it has been earnestly demanded to reduce their work and ensure more safety.
In addition, in a crane whose rated load is variable according to the direction of rotation, there has been a need to automatically brake and stop rotation of an upper rotary body with preventing the upper rotary body from being subject to an over-load.
In view thereof, Japanese Unexamined Patent Publication No. 61-211295 discloses a device including a sensor, as observer, for measuring the swinging amount of load to thereby carry out feedback control of the speed of rotation based on measurements obtained by the sensor.
It is, however, difficult to brake and stop the rotation of an upper rotary body properly by such feedback control because the swinging amount of load with the rotation of the upper rotary body is affected by external conditions such as wind. Moreover, it is very difficult to measure the swinging amount with a high precision. Accordingly, such feedback control is considered to be impracticable.
It is desirable to brake and stop the rotation of an upper rotary body as quickly as possible. On the other hand, however, the braking of an upper rotary body at a greater deceleration causes the load and the upper rotary body itself to have greater inertia force in the direction of the rotation. Consequently, the upper rotary body is subject to a greater load in the direction of lateral bending.
Moreover, a load in the direction of lateral bending is greatly dependent on the inclination angle of the upper rotary body. Accordingly, it is very important to detect the inclination angle with a high precision when controlling the stop and rotation of an upper rotary body.
Specifically, construction machines such as cranes equipped with an upper rotary body are not always placed in a perfectly horizontal position. In the case of mobile cranes and the like, especially, the setting place is often changed, and there are many cases in which they are operated in slightly inclined positions. As operation in such inclined positions delicately gives an influence to the stability and strength of the machines, a control has been demanded which takes this influence into account.
In connection with this influence, Japanese Unexamined Patent Publication No. 59-172385 discloses a device in which the inclination angle of a crane body is detected with respect to a forward and backward direction or sideways direction of a crane, and the operation radius of the crane is changed based on the detected inclination angle.
Also, Japanese Unexamined Patent Publication No. 59-227688 discloses a device in which the inclination angle of a crane body is detected, and one of two predetermined rated loads is selected according to the detected inclination angle.
Further, Japanese Unexamined Patent Publication No. 62-13620 discloses a device including a sensor provided on an upper rotary body for detecting the inclination angle, whereby braking is applied to the upper rotary body according to the inclination angle detected by the sensor at every moment.
Such conventional technology, however, have the following problems which must be solved:
In the devices of Japanese Unexamined Patent Publication Nos. 59-172385 and 59-227688, the inclination angle of a crane body with respect to a forward and backward direction or sideways direction is detected, and the operation radius of the crane or the rated load is changed
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patent: 4895262 (1990-01-01), Maso
patent: 5062266 (1991-11-01), Yoshimatsu
patent: 5160056 (1992-11-01), Yoshimatsu et al.
Fukushima Kouichi
Yoshimatsu Hideaki
Avila Stephen P.
Kabushiki Kaisha Kobe Seiko Sho
Mitchell David M.
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