Electronically controlled industrial trucks

• US 4,411,582 A
• Filed: 02/20/1981
• Issued: 10/25/1983
• Est. Priority Date: 08/20/1979
• Status: Expired due to Term

• Current Assignee: Komatsu Forklift Kabushiki Kaisha
• Original Assignee: Komatsu Forklift Kabushiki Kaisha
• Inventors: Nakada, Shoichi
• Primary Examiner(s): Sheridan, Robert G.
• Application Number:
  US06/236,191
• Time in Patent Office: 977 Days
• Field of Search: 414/629, 414/635, 414/636, 414/641, 414/674, 187/9 R, 187/9 E
• US Class Current: 414/636
• CPC Class Codes: B66F 9/0755 Position control; Position detectors
• CPC Class Codes: B66F 9/24 Electrical devices or systems

Abstract

An electronically controlled fork-lift truck having a tilt-cylinder controlled mast and a lift-cylinder controlled fork, comprising a control board mounted adjacent to a driver'"'"'s seat, the control board having formed thereon various push button switches and a display panel for displaying the heights of the fork, an electronic controller operatively connected with the control board for controlling the movements of the fork and mast, a fork height sensor for detecting the movement of the fork and generating signals denoting increments of that movement, and a tilt sensor for detecting the upright and a tilt-back position of the mast and providing a signal to stop the mast movement wherein the electronic controller can provide various functions including an automatic fork raising and lowering operation.

Claims

1. An electronic controller for controlling movements of a fork and a mast of a fork-lift truck wherein the movement of the fork is effected by a lifting mechanism and that of the mast is effected by a tilting mechanism, comprising:

first sensor means for detecting the movement of the fork and providing first signals denoting increments of that movement;

counter means for receiving said first signals and providing a count denoting the height of the fork along its range of movement;

memory means for storing data denoting the height of the fork and providing said stored data for comparison with said count;

means for effecting storage in said memory means;

first comparator means for comparing said count with the data from said memory means to provide a second signal for controlling the movement of the fork;

first actuator means adapted to receive said second signal and actuate said lifting mechanism in response thereto;

second sensor means for detecting an upright and a tilt-back position of the mast and providing a third signal to stop the mast movement;

second actuator means for actuating said tilt mechanism, said second actuator means being adapted to receive said third signal and to stop in response thereto;

base height switch means for providing a fourth signal indicating a predetermined base height whenever it is actuated by the fork;

second comparator means for comparing the count of said counter means with said fourth signal for correcting any errors of said count; and

a control board means including a plurality of switches for starting and stopping the movements of the fork and the mast, said control board means being operable by a human operator to provide for the storage of said count in a storage location wherein the address is determined by the operation of a particular switch and wherein the memory is addressable on subsequent operation of said particular switch to provide the stored count to the first comparator means.

2. An electronic controller as recited in claim 1 further comprising a voltage controller coupled between said first comparator and said first actuator means for controlling the voltage applied to said first actuator means for gradually increasing or decreasing the voltage applied thereto.

3. A fork-lift truck including a truck body, a driver'"'"'s seat, a mast pivotally mounted on the truck body, a tilt cylinder for effecting tilt movement of the mast, a fork mounted on the mast, and a lift cylinder for effecting up and down movements of the fork, comprising:

a control board mounted adjacent to said driver'"'"'s seat, said control board having a plurality of push button switches thereon for controlling the movements of said fork and mast, and a display panel for displaying the height of said fork;

electronic controller means operatively connected with said control board for controlling the movements of said fork and mast, said controller means having memory means for storing data denoting a height of the fork;

fork height sensor means for detecting the movement of said fork and generating first signals denoting increments of the movement thereof, said fork height sensor means being operatively connected with said electronic controller means, wherein said fork height sensor means comprises a photoelectric switch having a U-shaped beam emitting portion formed at the leading end thereof, and a circular slit plate rotatable with the up and down movements of said fork, said circular slit plate being adapted to move in and through the U-shaped beam emitting portion thereby intermittently blocking the beam;

tilt sensor means mounted on said truck body for detecting an upright and a tilt-back position of said mast and providing a second signal to stop the mast movement;

first actuator means for actuating said lift cylinder, said first actuator means being connected with and controlled by said electronic controller means; and

second actuator means for actuating said tilt cylinder, said second actuator being stopped upon receiving said second signal from said tilt sensor means.

4. A fork-lift truck as recited in claim 3 wherein said tilt sensor means comprises a pair of limit switches, one for detecting the upright position of the mast and the other for detecting the tilt-back position of the mast, and a cam plate mounted on said tilt cylinder, said cam plate being operatively associated with said limit switches.

5. A fork-lift truck as recited in claim 3 wherein said control board is mounted on a box-like arm pivotally mounted to said driver'"'"'s seat and wherein said electronic controller means is housed within said box-like arm.

6. A fork-lift truck as recited in claim 3 wherein said control board is mounted in a dash-board of the truck.

7. A fork-lift truck as recited in claim 3, 5 or 6 wherein the plurality of push button switches of said control board comprise a plurality of address switches, fork raising and lowering switches, an automatic fork raising or lowering switch, a fork height data storing switch, and mast tilting switches each for forwardly or backwardly.

8. A fork-lift truck as recited in claim 7 wherein the push button switches further include a switch for changing high and low speeds and a switch for automatically bringing said fork and mast into a normal running postures.