APPARATUS FOR INDUCTIVELY MONITORING THE MOVEMENT OF A PISTON WITHIN A CYLINDER OF AN INJECTION MOLDING MACHINE

• US 3,654,549 A
• Filed: 12/30/1968
• Issued: 04/04/1972
• Est. Priority Date: 12/30/1967
• Status: Expired due to Term

• Current Assignee: Jurg Von Ruti, Ludwig Maurer
• Original Assignee: Jurg Von Ruti, Ludwig Maurer
• Inventors: Maurer, Ludwig, Von Ruti, Jurg
• Primary Examiner(s): Rolinec, Rudolph V.
• Assistant Examiner(s): Corcoran, R. J.
• Application Number:
  US04/787,803
• Time in Patent Office: 1,191 Days
• Field of Search: 324/34PS,34D 73/313 336/179,30,45,130 340/195,282
• US Class Current: 324/207.16
• CPC Class Codes: F15B 15/2861 using magnetic means
• CPC Class Codes: G01D 5/2258 by a movable ferromagnetic element, e.g. core

Abstract

A method and apparatus wherein the movement of a cylinder and piston, one with respect to the other, is measured. The measurement is carried out by way of a transducer which converts the relative movement into an electrical magnitude. The transducer includes a piston component fixed to the piston so as to move therewith, this piston being formed in the interior of the cylinder with an axial bore. The transducer also has a cylinder component which is maintained at a location which does not change with respect to the cylinder and which extends at least in part into the bore of the piston, this latter component of the transducer being coaxial with the piston.

Claims

1. A measuring arrangement for use in an injection molding machine having a piston means, operatively mounted in hollow cylinder means, said arrangement measuring the extent of axial movement of one of said means relative to the other in response to introduction of fluid under pressure into said cylinder means, said arrangement comprising:

inductive measurement transducer means for converting the movement of said one of said means with respect to the other of said means into an electrical magnitude, said transducer means including a piston inductive component forming part of said piston means and forming a bore in said piston means, said piston inductive component being at least partially formed of ferromagnetic material, and a cylinder component having a fixed position relative to said cylinder means, said cylinder component including a coil axially secured to said cylinder means and a ferromagnetic core surrounded by said coil, so as to be coaxially aligned therewith, said coil and core extending into said bore formed by said piston inductive component, said piston and cylinder components having an inductive operational relationship with each other, said cylinder means having in its interior a partition fluidtightly surrounding said piston means and separating in said cylinder means on one side of said partition a pressure chamber, and, in said cylinder means, on the other side of said partition, a chamber which is at atmospheric pressure, said piston means having a piston portion situated in said pressure chamber and an extension extending fluid-tightly through, said partition iNto said chamber which is at atmospheric pressure, the latter extension being formed with said bore and receiving said said cylinder component of said transducer means.

2. The combination of claim 1 comprising a holding member fixedly connecting said cylinder component to said cylinder means.

3. The combination of claim 1 and wherein said cylinder component includes a pair of coaxial oppositely wound coils for providing temperature compensation.

4. The combination of claim 1 and wherein said piston portion of said piston means has a pair of opposed working surfaces which are of equal effective areas.