Wax Thermostat

• US 20170276056A1
• Filed: 03/24/2016
• Published: 09/28/2017
• Est. Priority Date: 03/24/2016
• Status: Active Application

• Current Assignee: Denso International America Incorporated (DENSO Corporation)
• Original Assignee: Denso International America Incorporated (DENSO Corporation)
• Inventors: SPENNY, Jason
• Granted Patent: US 10,287,965 B2
• Time in Patent Office: Days
• CPC Class Codes: F01P 7/16 by thermostatic control
• CPC Class Codes: G05D 23/02 with sensing element expanding and contracting in response to changes of temperature G05D23/13 takes precedence
• CPC Class Codes: G05D 23/021 the sensing element being a non-metallic solid, e.g. elastomer, paste
• CPC Class Codes: G05D 23/022 the sensing element being placed within a regulating fluid flow

Abstract

A wax motor thermostat for an engine cooling system. The thermostat includes a cylinder having at least a first wax portion and a second wax portion each configured to expand at different temperatures. A piston is movable in response to expansion of the first and second wax portions to move the wax motor thermostat from a closed position to a fully open position or a partially open position between the closed and fully open positions to allow coolant to flow through the wax motor thermostat.

Claims

1. A wax motor thermostat for an engine cooling system comprising:

a cylinder including at least a first wax portion and a second wax portion each configured to expand at different temperatures; and

a piston movable in response to expansion of the first and second wax portions to move the wax motor thermostat from a closed position to a fully open position, or to a partially open position between the closed and fully open positions, to allow coolant to flow through the wax motor thermostat.

2. The wax motor thermostat of claim 1, further comprising a spring biased to maintain the wax motor in the closed position.

3. The wax motor thermostat of claim 1, further comprising a valve plate having a valve seat, the piston is configured to raise a frame off of the valve seat to move the wax motor thermostat from the closed position to the partially open position and the fully open position.

4. The wax motor thermostat of claim 1, wherein the first and the second wax portions are configured to melt as the wax expands.

5. The wax motor thermostat of claim 1, further comprising a first washer between the first and second wax portions, and a second washer on a side of the second wax portion opposite to the first washer, each one of the first and the second washers having a tapered edge at an outer diameter thereof, the first and second washers are arranged within the cylinder such that both of the tapered edges contact an inner wall of the cylinder.

6. The wax motor thermostat of claim 5, wherein each one of the first and second washers includes a polymeric material.

7. The wax motor thermostat of claim 5, wherein each one of the first and second washers includes acetal.

8. The wax motor thermostat of claim 5, wherein the tapered edges deform against the inner wall of the cylinder when the first and second washers are heated, and the tapered edges are slidably movable along the inner wall.

9. The wax motor thermostat of claim 5, wherein:

each one of the first and second washers defines an aperture through which the piston extends;

a first barb extends from the piston and is seated on the first washer such that movement of the washer in response to expansion of the first wax portion moves the piston a first distance and moves the wax motor thermostat to the partially open position; and

a second barb extends from the piston and is seated on the second washer such that movement of the second washer in response to expansion of the second wax portion moves the piston a second distance to the fully open position.

10. The wax motor thermostat of claim 1, further comprising a first wax barrier layer between the first and second wax portions, and a second wax barrier layer on a side of the second wax portion opposite to the first wax barrier layer;

wherein the first wax barrier layer and the second wax barrier layer each have a higher melting point than the first wax portion and the second wax portion.

11. The wax motor thermostat of claim 1, further comprising:

a rotatable center sleeve seated in the cylinder and in receipt of the piston, the center sleeve threadably receives the piston such that rotation of the center sleeve moves the piston along a longitudinal axis of the cylinder and moves the wax motor thermostat from the closed position to the fully open position, or to a partially open position between the closed and the fully open positions;

a first wall rigidly mounted to an inner wall of the cylinder;

a second wall mounted to the center sleeve such that rotation of the second wall rotates the center sleeve;

a third wall mounted to the center sleeve such that rotation of the third wall rotates the center sleeve;

a tab rigidly mounted to the inner wall of the cylinder, the third wall abuts the tab when the wax motor thermostat is in the closed position;

a support surface on which the first wax portion and the second wax portion are seated, the first wax portion is between the first wall and the second wall, and the second wax portion is between the second wall and the third wall;

wherein;

expansion of the first wax portion causes the first wax portion to push against both the first wall and the second wall to rotate the center sleeve a first distance, which causes the piston to move along the longitudinal axis thereby moving the wax motor thermostat to the partially open position; and

expansion of the second wax portion subsequent to expansion of the first wax portion causes the second wax portion to push the third wall to rotate the center sleeve beyond the first distance to a second distance, which causes the piston to move along the longitudinal axis thereby moving the wax motor thermostat to the fully open position.

12. A wax motor thermostat for an engine cooling system comprising:

a cylinder including at least a first wax portion and a second wax portion each configured to expand at different temperatures;

a first washer between the first and the second wax portions, the first washer defining a first aperture;

a second washer on a side of the second wax portion opposite to the first washer;

a piston extending through the first aperture and the second aperture;

a first barb extending from the piston and seated on the first washer; and

a second barb extending from the piston and seated on the second washer;

wherein the piston is movable in response to expansion of the first and second wax portions to move the wax motor thermostat from a closed position to a fully open position or a partially open position between the closed and fully open positions to allow coolant to flow through the wax motor thermostat.

13. The wax motor thermostat of claim 12, wherein:

upon expansion of the first wax portion the first wax portion moves the first washer to apply force against the first barb to move the piston along a longitudinal axis of the cylinder and move the wax motor thermostat to the intermediate position; and

upon expansion of the second wax portion subsequent to expansion of the first wax portion, the second wax portion moves the second washer to apply force against the second barb to move the piston along the longitudinal axis and move the wax motor thermostat to the intermediate position.

14. The wax motor thermostat of claim 12, wherein the first and second wax portions are configured to melt as the wax expands.

15. The wax motor thermostat of claim 12, wherein:

each one of the first and second washers has a tapered edge at an outer diameter thereof, the first and second washers are arranged within the cylinder such that both of the tapered edges contact an inner wall of the cylinder; and

the tapered edges deform against the inner wall of the cylinder when the first and second washers are heated, and the tapered edges are slidably movable along the inner wall.

16. A wax motor thermostat for an engine cooling system comprising:

a cylinder having an inner wall;

a sleeve rotatably seated within the cylinder;

a piston seated within the sleeve such that rotation of the sleeve moves the piston along a longitudinal axis of the cylinder;

a first wall rigidly mounted to the inner wall of the cylinder;

a second wall mounted to the sleeve such that rotation of the second wall rotates the sleeve;

a third wall mounted to the sleeve such that rotation of the third wall rotates the sleeve;

a tab rigidly mounted to the inner wall of the cylinder, the third wall abuts the tab when the wax motor thermostat is in a closed position;

a first wax portion seated on a support surface and arranged between the first wall and the second wall; and

a second wax portion seated on the support surface and arranged between the second wall and the third wall;

wherein the first wax portion and the second wax portion are each configured to expand at different temperatures to move the wax motor thermostat from the closed position to a partially open position and a fully open position.

17. The wax motor thermostat of claim 16, wherein:

expansion of the first wax portion causes the first wax portion to push against both the first wall and the second wall to rotate the sleeve a first distance, which causes the piston to move along the longitudinal axis thereby moving the wax motor thermostat to the partially open position; and

expansion of the second wax portion subsequent to expansion of the first wax portion causes the second wax portion to push the third wall to rotate the sleeve beyond the first distance to a second distance, which causes the piston to move along the longitudinal axis thereby moving the wax motor thermostat to the fully open position.

18. The wax motor thermostat of claim 17, wherein the first and second wax portions are configured to melt as the wax expands.

19. The wax motor thermostat of claim 16, further comprising a torsion spring configured to maintain the wax motor thermostat in the closed position.