Warewash machine chemical sensor and related system and method

• US 9,521,941 B2
• Filed: 03/14/2013
• Issued: 12/20/2016
• Est. Priority Date: 08/21/2012
• Status: Active Grant

• Current Assignee: Premark FEG LLC (Illinois Tool Works Inc.)
• Original Assignee: Premark FEG LLC (Illinois Tool Works Inc.)
• Inventors: Dickey, Larry M., Fischer, David L., Newcomer, Jeffrey R., Watson, Michael T., Prybor, Brian R., Anim-Mensah, Alexander R.
• Primary Examiner(s): Barr, Michael
• Assistant Examiner(s): RIGGLEMAN, JASON PAUL
• Application Number:
  US13/826,480
• Publication Number:
  US 20140053881A1
• Time in Patent Office: 1,377 Days
• US Class Current: 1/1
• 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 15/4236 Arrangements to sterilize or disinfect dishes or washing liquids A47L15/4234 takes precedence
• CPC Class Codes: A47L 15/4293 Arrangements for programme selection, e.g. control panels; Indication of the selected programme, programme progress or other parameters of the programme, e.g. by using display panels
• CPC Class Codes: A47L 15/4297 Arrangements for detecting or measuring the condition of the washing water, e.g. turbidity
• CPC Class Codes: A47L 15/44 Devices for adding cleaning agents; Devices for dispensing cleaning agents, rinsing aids or deodorants
• CPC Class Codes: A47L 15/4418 in the form of liquids A47L15/4409, A47L15/4436, A47L15/4445 take precedence
• CPC Class Codes: A47L 2401/023 Quantity or concentration of the consumable product
• CPC Class Codes: A47L 2401/30 Variation of electrical, magnetical or optical quantities
• CPC Class Codes: A47L 2501/26 Indication or alarm to the controlling device or to the user

Abstract

A flow through chemical sensor includes a housing having a through passage along which chemical can flow, a sidewall of the housing having first and second openings that communicate with the through passage. A first electrode is mounted on the housing and aligned with the first opening, the first electrode of a plate configuration with a unitary depression that extends through the first opening and to a peripheral edge of the through passage. A second electrode is mounted on the housing and aligned with the second opening, the second electrode of a plate configuration with a unitary depression that extends through the second opening and to the peripheral edge of the through passage. A method of detecting presence or absence of chemical is also provided.

Claims

1. A flow through chemical sensor, comprising:

a housing having a through passage along which chemical can flow, a sidewall of the housing having first and second openings that communicate with the through passage;

a first electrode mounted on the housing and aligned with the first opening, the first electrode of a plate configuration with a unitary depression that extends inward through the first opening and to at least a peripheral edge of the through passage such that an inwardly facing surface of the unitary depression can contact chemical flowing through the passage;

a second electrode mounted on the housing and aligned with the second opening, the second electrode of a plate configuration with a unitary depression that extends inward through the second opening and to at least the peripheral edge of the through passage such that an inwardly facing surface of the unitary depression of the second electrode can contact chemical flowing through the passage.

2. The flow through chemical sensor of claim 1 wherein:

a first o-ring is positioned between the housing and the first electrode and the first electrode is secured to the housing by way of a first fastener that provides a clamping force of the first electrode against the first o-ring for sealing, wherein the unitary depression of the first electrode extends through an opening of the first o-ring; and

a second o-ring is positioned between the housing and the second electrode and the second electrode is secured to the housing by way of a second fastener that provides a clamping force of the second electrode against the second o-ring for sealing, wherein the unitary depression of the second electrode extends through an opening of the second o-ring.

3. The flow through chemical sensor of claim 2 wherein:

the first electrode includes a first lead arm configured for connection with a wire terminal; and

the second electrode includes a second lead arm configured for connection with a wire terminal.

4. A warewash machine including the flow through chemical sensor of claim 1, wherein the flow through chemical sensor is located in a chemical feed line for delivering chemical directly or indirectly to a chamber of the machine.

5. The warewash machine of claim 4 wherein:

the flow through chemical sensor is connected in a chemical detection circuit via the first and second electrodes;

a controller of the machine is configured to apply a periodic excitation signal to the chemical detection circuit;

the chemical detection circuit is configured so that the flow through chemical sensor attenuates the periodic excitation signal according to impedance level of the chemical such that a level of attenuation varies inversely with impedance of the chemical and the sensor causes little or no attenuation in the absence of the chemical;

the controller further configured to evaluate the attenuated signal to determine the presence or absence of chemical and, in the absence of chemical to produce an operator alert.

6. The warewash machine of claim 5 wherein:

the warewash machine includes a user interface that enables an operator to identify the chemical being used and the controller is configured to automatically define a frequency of the applied periodic excitation signal according to operator selection of the chemical being used.

7. A flow through chemical sensor, comprising:

a housing having a through passage along which chemical can flow, a sidewall of the housing having first and second openings that communicate with the through passage;

a first electrode mounted on the housing and aligned with the first opening, the first electrode of a plate configuration with a unitary depression that extends inward through the first opening and to a peripheral edge of the through passage;

a second electrode mounted on the housing and aligned with the second opening, the second electrode of a plate configuration with a unitary depression that extends inward through the second opening and to the peripheral edge of the through passage;

a first o-ring is positioned between the housing and the first electrode and the first electrode is secured to the housing by way of a first fastener that provides a clamping force of the first electrode against the first o-ring for sealing, wherein the unitary depression of the first electrode extends through an opening of the first o-ring; and

a second o-ring is positioned between the housing and the second electrode and the second electrode is secured to the housing by way of a second fastener that provides a clamping force of the second electrode against the second o-ring for sealing, wherein the unitary depression of the second electrode extends through an opening of the second o-ring.

8. The flow through chemical sensor of claim 7 wherein:

the first electrode includes a first lead arm configured for connection with a wire terminal; and

the second electrode includes a second lead arm configured for connection with a wire terminal.