Methods for controlling the concentration of detergents

• US 5,370,743 A
• Filed: 01/12/1993
• Issued: 12/06/1994
• Est. Priority Date: 01/21/1992
• Status: Expired due to Fees

• Current Assignee: SpeedFam Clean System Co., Ltd. (Obara Group, Inc.)
• Original Assignee: Clear Technology Incorporated, SpeedFam Clean System Co., Ltd. (Obara Group, Inc.)
• Inventors: Nishizawa, Kazuo, Usui, Eiji
• Primary Examiner(s): Dean, Richard O.
• Assistant Examiner(s): CHAUDHRY, SAEED T
• Application Number:
  US08/003,128
• Time in Patent Office: 693 Days
• Field of Search: 134/10, 134/25.2, 134/18, 134/57 R, 134/57 D, 222/52, 137/93
• US Class Current: 134/18
• CPC Class Codes: A47L 15/0055 Metering or indication of used products, e.g. type or quantity of detergent, rinse aid or salt; for measuring or controlling the product concentration
• CPC Class Codes: A47L 2401/30 Variation of electrical, magnetical or optical quantities
• CPC Class Codes: A47L 2501/07 Consumable products, e.g. detergent, rinse aids or salt
• CPC Class Codes: D06F 2103/22 Content of detergent or additives
• CPC Class Codes: D06F 2105/42 Detergent or additive supply
• CPC Class Codes: D06F 2105/58 Indications or alarms to the control system or to the user
• CPC Class Codes: D06F 2105/60 Audible signals
• CPC Class Codes: D06F 34/22 Condition of the washing liquid, e.g. turbidity
• CPC Class Codes: G05D 21/02 characterised by the use of electric means

Abstract

Methods and apparatus for automatically controlling the concentration of a detergent in a cleaning solution determine the electrical conductivity Y of a cleaning solution 2 with a sensor 4, convert the electrical conductivity Y into the detergent concentration X using equation Y=aX+b (wherein Y=electrical conductivity of the cleaning solution, X=concentration of the detergent, a=inherent factor of the detergent, and b=electrical conductivity of the solvent), compare the converted detergent concentration with a preset value given in terms of detergent concentration, and actuate concentration controlling means according to the result of comparison.

Claims

1. A method for controlling the detergent concentration comprising the steps of determining the electrical conductivity of a cleaning solution containing a detergent in a cleaning vessel with a sensor, converting the determined electrical conductivity into the concentration of the detergent using equation Y=aX+b (wherein Y=electrical conductivity of the cleaning solution, X=concentration of the detergent, a=inherent factor of the detergent, and b=electrical conductivity of the solvent), comparing the converted detergent concentration with a preset value given in terms of detergent concentration, and actuating concentration controlling means according to the result of comparison.

2. A detergent concentration controlling method according to claim 1, in which the preset value consists of upper and lower limits of a proper concentration range of the detergent in the cleaning solution, detergent concentration controlling means starting the supply of a raw detergent when the detergent concentration of the cleaning solution falls to the lower limit and stopping the supply when the detergent concentration rises back to the upper limit.

3. A detergent concentration controlling method according to claim 1, in which the preset value consists of upper and lower limits of a proper concentration range of the detergent in the cleaning solution and an intermediate point therebetween, detergent concentration controlling means starting the supply of a raw detergent when the detergent concentration falls to the lower limit, stopping the supply thereof when the detergent concentration rises back to the intermediate point, starting the supply of a solvent when the detergent concentration rises to the upper limit and stopping the supply thereof when the detergent concentration falls back to the intermediate point.