Device for measuring powder flow rate and apparatus and method for supplying powder

• US 5,929,343 A
• Filed: 11/06/1996
• Issued: 07/27/1999
• Est. Priority Date: 03/30/1995
• Status: Expired due to Fees

• Current Assignee: Nihon Parkerizing Company Limited
• Original Assignee: Nihon Parkerizing Company Limited
• Inventors: Kumata, Mitsuyoshi, Kanai, Keiji, Yamamoto, Masahiro, Ishikawa, Yutaka, Murai, Hiroki
• Primary Examiner(s): Dougherty, Elizabeth L.
• Application Number:
  US08/737,270
• Time in Patent Office: 993 Days
• Field of Search: 73/861, 73/861.08, 73/861.12, 73/861.02, 73/861.04, 73/861.06, 324/627, 361/816
• US Class Current: 73/861.08
• CPC Class Codes: G01F 1/56 by using electric or magnetic effects G01F1/66 takes precedence
• CPC Class Codes: G01F 1/64 by measuring electrical currents passing through the fluid flow; measuring electrical potential generated by the fluid flow, e.g. by electrochemical, contact or friction effects G01F1/58 takes precedence
• CPC Class Codes: G01F 1/74 Devices for measuring flow of a fluid or flow of a fluent solid material in suspension in another fluid

Abstract

A pair of measuring electrodes (63, 64; 73, 74) are provided along the circumferential portion of a cylindrical measuring tube (62; 72) made of an insulating material. The flow rate of powder passing through the measuring tube is measured as a change in the electrostatic capacity between the pair of measuring electrodes.

Claims

1. A powder flow rate measuring device comprising:

a cylindrical measuring tube made of an insulating material;

a pair of measuring electrodes provided along a circumferential portion of the measuring tube, the pair of measuring electrodes being band-like members provided on the circumferential portion of the measuring tube spirally in parallel with each other, and

a band-like guard electrode provided on the circumferential portion of the measuring tube spirally between the pair of measuring electrodes, the guard electrode being narrower than the measuring electrodes,

wherein a flow rate of powder passing through the measuring tube is measured as a change in electrostatic capacity between the pair of measuring electrodes.

2. The device according to claim 1 wherein the pair of measuring electrodes are formed on the circumferential portion of the measuring tube by being printed thereon.

3. The device according to claim 1 further comprising:

an external cylinder for electrically shielding the measuring tube;

a power source for applying a voltage across the pair of measuring electrodes;

a cable, connected to one of the pair of measuring electrodes, for picking up an electric current flowing through the pair of measuring electrodes;

a shielding tube for electrically shielding the cable; and

an amplifier connected to the cable,

wherein an output from the amplifier is connected to the external cylinder and the shielding tube.

4. The device according to claim 3 wherein the external cylinder is provided on the circumferential portion of the measuring tube through a sealant.