FLUID WARMER WITH SWITCH ASSEMBLY

• US 20100276411A1
• Filed: 07/19/2010
• Published: 11/04/2010
• Est. Priority Date: 09/10/2008
• Status: Active Grant

• Current Assignee: Enthermics Medical Systems, Inc.
• Original Assignee: Enthermics Medical Systems, Inc.
• Inventors: Hansen, William J., Smith, Terence T.
• Granted Patent: US 8,362,402 B2
• Time in Patent Office: Days
• US Class Current: 219/385
• CPC Class Codes: A61M 5/44 having means for cooling or heating the devices or media
• CPC Class Codes: A61M 5/445 the media being heated in the reservoir, e.g. warming bloodbags

Abstract

A fluid warmer is disclosed. The fluid warmer includes a support surface, a heating element configured to selectively heat the support surface, and a switch assembly extending through the support surface. The switch assembly includes a switch, a movable switch plate, and a thermocouple. The switch has at least two states, one of which indicates the presence of an item on the support surface. The movable switch plate operably links to the switch to move the switch between the states and further includes a contact surface that contacts an item placed on the support surface. One or more thermocouples are embedded in the movable switch plate below the contact surface. The movable switch plate comprises a material having a thermal conductivity that permits the thermocouple(s) embedded in the switch plate to measure a temperature of an item placed on the support surface within a predetermined period of time.

Claims

1. A fluid warmer comprising:

a support surface;

a heating element configured to selectively heat the support surface; and

a switch assembly extending through the support surface, the switch assembly including

a switch having at least two states, one of the at least two states indicating a presence of an item on the support surface;

a movable switch plate operably linked to the switch to move the switch between the at least two states, the movable switch plate including a contact surface that contacts an item placed on the support surface; and

a thermocouple embedded in the movable switch plate below the contact surface;

wherein the movable switch plate comprises a material having a thermal conductivity that permits the thermocouple embedded in the switch plate to measure a temperature of an item placed on the support surface within a predetermined period of time.

2. The fluid warmer of claim 1, wherein the movable switch plate comprises a heat conducting member in which an end of the thermocouple is embedded and wherein the heat conducting member also forms at least a portion of the contact surface of the movable switch plate.

3. The fluid warmer of claim 2, wherein the heat conducting member comprises a material having a thermal conductivity exceeding 200 W·

m<sup>−

1</sup>·

K<sup>−

1</sup>.

4. The fluid warmer of claim 2, wherein the heat conducting member comprises copper.

5. The fluid warmer of claim 1, wherein the movable switch plate includes a first portion and a second portion and wherein a cavity formed in the second portion that receives the first portion.

6. The fluid warmer of claim 5, wherein the first portion has at least one bay formed therein that receives an end of the thermocouple.

7. The fluid warmer of claim 6, wherein, when the first portion is received in the second portion, a space is defined between the first portion and the second portion.

8. The fluid warmer of claim 7, wherein the second portion includes a passage running from the cavity through the second portion, thereby providing a pathway for a wire of the thermocouple from the at least one bay in the first portion, through the space between the first portion and the second portion, and through the passage in the second portion to an exterior of the movable switch plate.

9. The fluid warmer of claim 1, wherein an air gap separates the movable switch plate from the support surface of the fluid warmer, thereby thermally isolating the movable switch plate from the support surface of the fluid warmer.

10. The fluid warmer of claim 1, wherein the movable switch plate includes a downwardly extending projection that engages an actuatable part of the switch.

11. The fluid warmer of claim 1, wherein the switch assembly further includes a switch housing that supports the switch and the movable switch plate.

12. The fluid warmer of claim 11, wherein the movable switch plate is pivotally attached to the switch housing.

13. The fluid warmer of claim 12, wherein the movable switch plate is pivotally attached to the switch housing by a pivot pin.

14. The fluid warmer of claim 11, wherein the switch housing includes a flange which is configured to position the switch assembly relative to a support surface of the fluid warmer such that the contact surface of the movable switch plate resides above the support surface.

15. The fluid warmer of claim 1, wherein the switch and movable switch plate constitute a presence sensor configured to detect the item on the contact surface.

16. The fluid warmer of claim 15, wherein the presence sensor provides a signal indicating the item is disposed on the contact surface and the thermocouple provides a signal indicating a temperature of the item disposed on the contact surface.

17. A switch assembly for use in a support surface of a fluid warmer, the switch assembly comprising:

a presence sensor configured to detect a presence of an item engaging a contact surface of the presence sensor, the presence sensor providing a signal indicating the item is disposed on the support surface of the fluid warmer;

a thermocouple embedded in the presence sensor below the contact surface, the thermocouple providing a signal indicating a temperature of the item disposed on the contact surface;

wherein the contact surface of the presence sensor comprises a material having a thermal conductivity that permits the thermocouple embedded in the presence sensor to measure the temperature of the item on the contact surface within a predetermined period of time, the material of the contact surface being thermally isolated for the support surface of the fluid warmer.

18. The switch assembly of claim 17, wherein the presence sensor comprises:

a switch having at least two states; and

a movable switch plate operably linked to the switch to move the switch between the at least two states depending on a presence of an item on the contact surface of the movable switch plate.

19. The switch assembly of claim 17, wherein the presence sensor comprises a heat conducting member in which an end of the thermocouple is embedded and wherein the heat conducting member also forms at least a portion of the contact surface of the presence sensor.

20. The switch assembly of claim 19, wherein the heat conducting member comprises a material having a thermal conductivity exceeding 200 W·

m<sup>−

1</sup>·

K<sup>−

1</sup>.