Kabushiki Kaisha Toyoda Jidoshokki Seisakusho

Kabushiki Kaisha Meidensha

Mineo Ozeki

Susumu Yoshida

Yasuyuki Miyazaki

Masaru Kawamata

Katsumi Yuki

A control device for loading and unloading mechanism adapted to be incorporated in a fork lift truck comprises a sensor unit 100 including a lifting height sensor 102, a tilting angle sensor 104, and a load sensor 106, a control unit 200 comprising a control command producing circuit 240 constituted by a microcomputer 230 producing a control command on the basis of comparing calculation between the output of the sensor unit 100 and the concerned data stored in the microcomputer 230. The control device further comprises actuators 322, 324 including servomotor driving circuit therein responsive to the control command fed from the control unit 200, and a hydraulic pressure driving circuit 340 for hydraulically controlling a lift cylinder 346 and a tilt cylinder 348 in accordance with the corresponding output of each actuator, respectively. The control device is capable of effecting a automatic running attitude control due to the data stored in the microcomputer 230. The control device further makes it possible to automatically effect a series of sequential loading and unloading work including a lifting height operation and a tilting angle control. Preferably, the control device comprises a means for manually adjusting an attitude angle of the fork during loading and unloading work. Further, in view of safety, the control device is constituted so that an adjustable running attitude angle of the fork is limited to a predetermined region.

Control device for loading and unloading mechanism

A control device for loading and unloading mechanism adapted to be incorporated in a fork lift truck comprises a sensor unit 100 including a lifting height sensor 102 and a load sensor 106, a control unit 200 comprising a control command producing circuit 240 constituted by a microcomputer 230 producing a control command on the basis of comparing calculation between the output of the sensor unit 100 and the concerned data stored in the microcomputer 230, a servomotor driving circuit 322' responsive to the control command indicative of a valve opening angle, and a hydraulic pressure driving circuit 340 for actuating a lift cylinder in accordance with the output of the servomotor driving circuit 322'. The control device is constituted so that, when the work for piling or unloading a load on a shelf is effected based on the stored lifting height data, the two positions required for piling and unloading can be stored in the same address allotted to the corresponding shelf can be stored. The control device is constituted so that, when lifting height data is stored in the microcomputer, an indication for confirming data storage is added to the stored lifting height data, thereby enabling to prevent an automatic lifting height control from being erroneously effected.

A control device for loading and unloading mechanism adapted to be incorporated in a fork lift truck comprises a sensor unit 100 including a lifting height sensor 102, a control unit 200 comprising a control command producing circuit 240 constituted by a microcomputer 230 producing a control command on the basis of comparing calculation between the output of the sensor unit 100 and the concerned data stored in the microcomputer 230, and a driving unit 300 producing a driving output signal so as to the lifting height of the fork 18 in accordance with the control command fed from the control unit 200. The control device includes a component operable for inhibiting storage of sampled lifting height data when the actual lifting height data are not within an allowed range, thereby to prevent erroneous operation based on erroneous data and to effect smooth follow-up speed control to the target height when automatic lifting height control is effected. The control device further comprises structure for slowly stopping the fork at the time of the automatic lifting height control. Prior to the automatic lifting height control, when lifting height data is stored in the microcomputer 230, the control device is designed so that lifting height data within a predetermined range can be sampled. Furthermore, the valve opening angle of the control valve for actuating a lift cylinder 346 is limited to a predetermined range, thereby stabilizing a lifting height speed.

An improved fork lift truck control system using a microcomputer, which comprises a sensing unit including a first sensor for detecting a lift height of a fork above its lowest position and a second sensor for detecting a tilting angle of an upright with respect to a neutral position of the upright including an input interface circuit for interfacing the sensing unit and control unit which has: (a) a lifting height counting circuit which counts the number of pulses produced on a basis of two photo-converted electrical signals fed from two photocouplers constituting the first sensor, the signals having a phase difference of 90.degree. from each other, so that an accurate measurement of the lifting height of the fork can be made; (b) an analog-to-digital converter which produces a bit string according to an output signal from the second sensor; and (c) an abnormal detection facility which detects a defective analog-to-digital converter and second sensor by comparing the bit string presently outputted from the analog-to-digital converter with each of predetermined bit strings that would be produced if the analog-to-digital converter operates normally.

Input circuit of a fork lift truck control system for a fork lift truck

A method and system for horizontally controlling a fork for a fork lift truck to be positioned at a position parallel with respect to the ground, according to the loads mounted on the fork. The target backward tilting angle of the upright is previously determined as a function of the load on the fork and stored in a memory of a microcomputer. Therefore, the microcomputer outputs an upright forward/backward tilting operation command signals to a tilt servo mechanism on the basis of signals outputted from a load sensor and a potentiometer to detect upright tilt angles. The tilt servo mechanism according to the present invention can adjust and stop the upright at a target backward tilting angle at a low speed without applying a shock to the load.

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Ichinomiya, Japan

Mineo Ozeki