Adaptive load-clamping system

• US 6,390,751 B2
• Filed: 03/28/2001
• Issued: 05/21/2002
• Est. Priority Date: 10/07/1998
• Status: Expired due to Term

• Current Assignee: Cascade Corporation (Toyota Motor Corporation)
• Original Assignee: Cascade Corporation (Toyota Motor Corporation)
• Inventors: Jordan, Dean Clark, Seaberg, Richard D.
• Primary Examiner(s): Keenan, James W.
• Application Number:
  US09/820,246
• Publication Number:
  US 20020009356A1
• Time in Patent Office: 419 Days
• Field of Search: 414/21, 414/621, 414/636, 414/635, 294/88, 294/907, 187/224, 901/34
• US Class Current: 414/21
• CPC Class Codes: B25J 13/082 Grasping-force detectors in general G01L5/16, G01L5/22
• CPC Class Codes: B66F 9/184 Roll clamps
• CPC Class Codes: B66F 9/22 Hydraulic devices or systems
• CPC Class Codes: Y10S 294/907 Sensor controlled device

Abstract

A fluid power load-clamping system includes at least one fluid valve for variably regulating the maximum fluid pressure causing closure of the clamp. Preferably the valve increases the maximum fluid pressure automatically in relation to the measured magnitude of the weight of the load to regulate the load-gripping force. A controller causes the valve to permit a relatively high maximum fluid pressure as the clamp closes toward the load to enable high initial clamp closure speed. Thereafter the valve automatically reduces the maximum pressure as the clamping surfaces close into a predetermined relationship with the load, and then increases the maximum pressure to regulate the gripping force. Other preferable features include continuous weight-responsive automatic regulation of the gripping pressure while the load is supported by the clamp, and compensation of the weight measurement for the longitudinally-extensible position of the lifting mechanism, to maximize the accuracy of the load-weight measurement. Gripping pressure regulation is operable in response to linear load-lifting or tilting load-lifting, without concurrent clamp closure actuation. Different predetermined relationships between the weight of the load and the maximum gripping pressure are selectable alternatively. A gravity-referenced tilt controller adjusts the load automatically to an attitude which is untilted with respect to gravity. Lowering of the lifting mechanism is automatically prevented in response to the setting down of the load.

Claims

1. A load-handling clamp having selectively closable and openable load-engaging surfaces for selectively gripping and releasing a load positioned between said surfaces, said clamp comprising:

(a) at least one fluid power actuator connected to at least one of said surfaces for selectively closing said surfaces relative to each other to grip said load;

(b) at least one fluid valve assembly connected to said actuator for variably regulating the maximum fluid pressure causing said actuator to close said surfaces relative to each other;

(c) an electrical controller connected to said valve assembly automatically operable, in response to the weight of said load, to cause said valve assembly to increase said maximum fluid pressure variably in relation to the magnitude of said weight;

(d) an elongate, longitudinally-extensible lifting mechanism for lifting said load to enable said load to be weighed, said lifting mechanism supporting the weight of said load longitudinally by means of at least one reactive force in said mechanism which is variably dependent upon the longitudinally-extensible position of said mechanism;

(e) said controller being operable to sense the magnitude of said reactive force and to determine therefrom the magnitude of said weight of said load independently of changes in said longitudinally-extensible position of said mechanism effective to vary said reactive force.

2. A load-handling clamp having selectively closable and openable load-engaging surfaces for selectively gripping and releasing a load positioned between said surfaces, said clamp comprising:

(a) at least one fluid power actuator connected to at least one of said surfaces for selectively closing said surfaces relative to each other to grip said load;

(b) at least one fluid valve assembly connected to said actuator for variably regulating the maximum fluid pressure causing said actuator to close said surfaces relative to each other;

(c) a lifting mechanism operable, in response to actuation of a tilt selector, to lift said load by tilting said load to enable said load to be weighed; and

(d) an electrical controller connected to said valve assembly automatically operable, in response to the weight of said load, to cause said valve assembly to increase said maximum fluid pressure variably in relation to variations in the magnitude of said weight caused solely by said actuation of said tilt selector.