Conveyor system utilizing linear motor

• US 4,841,869 A
• Filed: 12/09/1988
• Issued: 06/27/1989
• Est. Priority Date: 01/27/1986
• Status: Expired due to Term

• Current Assignee: Daifuki Company Limited
• Original Assignee: Daifuki Company Limited
• Inventors: Takeuchi, Toshiyuki, Tsuneta, Masayuki
• Primary Examiner(s): Peters, Jr., Joseph F.
• Assistant Examiner(s): Swinehart, Edwin L.
• Application Number:
  US07/283,269
• Time in Patent Office: 200 Days
• Field of Search: 104/88, 104/140, 104/247, 104/290, 104/292, 104/295, 105/3, 105/4.1, 318/38, 318/135, 318/687
• US Class Current: 104/292
• CPC Class Codes: B60L 13/04 Magnetic suspension or levitation for vehicles
• CPC Class Codes: B60L 2200/26 Rail vehicles
• CPC Class Codes: B61B 13/12 Systems with propulsion devices between or alongside the rails, e.g. pneumatic systems cable traction B61B9/00; car shunting devices B61J

Abstract

A conveyor system utilizing the linear motor, comprising a conveyor cart and a guide rail for movably supporting the conveyor cart. The guide rail includes primary coils, and the conveyor cart includes a flexible secondary conductor extending longitudinally of the cart so as to follow the guide rail. The primary coils comprise a station primary coil disposed at each loading and unloading station for stopping and starting the converyor cart, two primary coils adjacent opposite ends of the station primary coil for decelerating the conveyor cart that is to be stopped at the station by the station primary coil and for accelerating the conveyor cart having started from the station to a target running speed, and a plurality of intermediate accelerating primary coils disposed between two adjacent stations for accelerating the conveyor cart to maintain the latter at the target running speed.

Claims

1. A conveyor system utilizing a linear motor, comprising;

a conveyor cart (A) including a pair of propelling wheels for supporting the same,

a guide rail (B) for movably supporting said conveyor cart (A),

a linear motor including,

primary coil means (C) mounted on said guide rail (B), and

a conductor (D) mounted on said conveyor cart (A) and horizontally opposed to said primary coil means (C),

wherein said conveyor cart (A) includes at lateral sides thereof a plurality of rollers (8), said rollers (8) being placed in rotatable contact with a horizontal face of said guide rail (B) for following horizontal flextion of the same

wherein said guide rail (B) is an integral structure including side walls interspersed with a constant distance therebetween for outwardly contacting said plurality of rollers (8), a rail portion (1A) for supporting said propelling wheels (7) against inner faces of said side walls and a bottom portion for supporting said primary coil (C), and

wherein said conductor (D) includes conductor portions (D1, D2) formed continuously with each other and horizontally flexes by a pivot mechanism, said conductor (D) together with said rollers (8) horizontally flexing to follow the horizontal flextion of said guide rail (B).

2. A conveyor system as claimed in claim 1 wherein said primary coil means (C) includes a stopping primary coil (C1) for generating a propulsive force to stop said conveyor cart (A) at a target stopping position, said stopping primary coil (C1) being electrified under control by electrification control means for deceleration (100A) adapted to calculate a propulsive force each time said conveyor cart (A) advances a predetermined distance, for causing said conveyor cart (A) to advance a next predetermined distance, and to amend the propulsive force calculated, in response to a change in speed resulting from a previous generation of the propulsive force.

3. A conveyor system as claimed in claim 2 wherein said electrification control means for deceleration (100A) is adapted to calculate the propulsive force for generation each time said conveyor cart (A) advances the predetermined distance on the basis of a difference between a running speed at a current position and a target speed at a position that the conveyor cart reaches after advancing the predetermined distance from the current position, the predetermined distance, and a weight of said conveyor cart, and to derive the weight of said conveyor cart for a second and subsequent calculations of the propulsive force on the basis of speed variations resulting from the propulsive force applied the previous times.

4. A conveyor system as claimed in claim 3 wherein said primary coil means (C) further includes a negative propulsion primary coil (C2) for applying a negative propulsive force to said conveyor cart (A), said negative propulsion primary coil (C2) being disposed adjacent said stopping primary coil (C1).

5. A conveyor system as claimed in claim 4 wherein said negative propulsion primary coil (C2) is utilized also for accelerating said conveyor cart (A) started from said stopping primary coil (C1).

6. A conveyor system as claimed in claim 5 wherein said conveyor cart (A) includes a memory medium (15) for storing destination data, and wherein electrification control means for acceleration and deceleration (100B) adapted to control electrification of said negative propulsion primary coil (C2) and said electrification control means for deceleration (100A) include reading means (16) for reading the data stored in said memory medium (15).

7. A conveyor system as claimed in claim 1 wherein said primary coil means (C) includes an intermediate accelerating primary coil (C3) for accelerating said conveyor cart (A) to a target speed, said intermediate accelerating primary coil (C3) being electrified under control by electrification control means for intermediate acceleration (100C) adapted to calculate a propulsive force on the basis of a difference between said target speed and an advancing speed of said conveyor cart (A), a weight of said conveyor cart (A), and a predetermined period of time for applying the propulsive force or a predetermined distance said conveyor cart (A) advances while the propulsive force is applied, and to electrify said intermediate primary coil (C3) for said predetermined period of time.

8. A conveyor system as claimed in claim 7 wherein said primary coil means (C) further includes a stopping primary coil (C1) for generating a propulsive force to stop said conveyor cart (A) at a target stopping position, and a negative propulsion primary coil (C2) for applying a negative propulsive force to said conveyor cart (A), said negative propulsion primary coil (C2) being disposed adjacent said stopping primary coil (C1).

9. A conveyor system as claimed in claim 8 wherein said negative propulsion primary coil (C2) is utilized also for accelerating said conveyor cart (A) started from said stopping primary coil (C1).

10. A conveyor system as claimed in claim 9 wherein said conveyor cart (A) includes a memory medium (15) for storing destination data, and wherein electrification control means for acceleration and deceleration (100B) adapted to control electrification of said negative propulsion primary coil (C2) and said electrification control means for deceleration (100A) include reading means (16) for reading the data stored in said memory medium (15).

11. A conveyor system as claimed in claim 1, further including:

a station (ST) for mounting and dismounting load to and from said conveyor cart (A) and disposed adjacent said guide rail (B),

a retaining member (11) attached to said conveyor cart (A) and formed of a ferromagnetic material, and

an electromagnet (10) disposed at a lower portion of the inner face of said guide rail (B) adjacent said station so as to be in opposed contact with said retaining member (11),

wherein said electromagnet (10) magnetically pulls said retaining portion (11) thereby retaining said conveyor cart (A) at a predetermined position of said station (ST).

12. A conveyor system as claimed in claim 11, further including:

a power line (E) for supplying power to said primary coil (C) for activating said linear motor, and

a signal line (F) for transmitting propelling control signals for the conveyor cart (A),

wherein said power line (E) is attached to an inner side of said guide rail (B) and said signal line (F) is attached to an outer side of guide rail (B) and is electrically insulated from said power line (E) by said guide rail (B).

13. A conveyor system as claimed in claim 12, further including:

an article carrying deck (4) disposed at an upper portion of said conveyor cart (A), and

a suction device (K) for sucking air from an interior of said guide rail (B), checking dust contained in the air by a filter (214) and then exhausting the cleaned air,

wherein said guide rail (B) has a cross section with an upper opening, such that said conveyor cart (A) travels in said guide rail (B) while exposing said article carrying deck (4) through said upper opening towards an upper outer portion of said guide rail (B).