Thermal bypass valve using shape memory alloys

Patent metadata

Field	Value
Publication number	US-9951858-B2
Application number	US-201514612964-A
Country	US
Kind code	B2
Filing date	Feb 3, 2015
Priority date	Feb 14, 2014
Publication date	Apr 24, 2018
Grant date	Apr 24, 2018

Abstract

A transmission fluid circuit for regulating the flow of a fluid includes a transmission, a cooler, and a valve. The valve includes a housing, a spool, and an actuator including a smart material. The spool is movable inside the housing between a first position and a second position. The smart material is configured to be in an activated state in response to the fluid exhibiting at least a first temperature and to be in a deactivated state in response to the fluid being a sufficient number of degrees less than the first temperature. The fluid flows from the housing to the transmission and from the transmission to the housing when the spool is in the first position. The fluid flows from the housing to the cooler, from the cooler to the transmission, and from the transmission to the housing when the spool is in the second position.

First claim

The invention claimed is:

1. A transmission fluid circuit for regulating a flow of a fluid, the transmission fluid circuit comprising:
a transmission configured for receiving and expelling the fluid;
a cooler configured for receiving and expelling the fluid; and
a valve configured for directing the flow of the fluid received from the transmission to one of the transmission and the cooler, the valve including:
a housing defining a cavity extending longitudinally between a first end and a second end, wherein the cavity is configured for receiving and expelling the fluid;
a spool disposed in the cavity and movable longitudinally therein between a first position and a second position;
an actuator attached to the spool and including a smart material configured as a straight wire and disposed in the fluid;
a biasing device disposed in the cavity and attached to the spool; and
a fluid passage for containing the flow of the fluid from the transmission to the cavity;

wherein the straight wire of smart material is disposed in the fluid passage and is coaxial with the flow of the fluid from the transmission to the cavity when the spool is in both the first position and the second position such that the temperature of the entire straight wire of smart material is substantially equal to the temperature of the fluid flowing from the transmission to the cavity when the spool is in both the first position and the second position;
wherein the actuator is configured to move the spool from the first position to the second position;
wherein the smart material is configured to be in an activated state in response to the fluid being at least a first temperature such that the activated smart material causes the actuator to move the spool to the second position;
wherein the smart material is configured to be in a deactivated state in response to the fluid being a sufficient number of degrees less than the first temperature such that the deactivated smart material allows the biasing device to move the spool to the first position;
wherein the fluid is permitted to flow from the cavity to the transmission and from the transmission to the cavity when the spool is in the first position; and
wherein the fluid is permitted to flow from the cavity to the cooler, from the cooler to the transmission, and from the transmission to the cavity when the spool is in the second position.

2. The transmission fluid circuit of claim 1 , wherein the spool includes:
a first section;
a second section longitudinally spaced from the first section; and
an intermediate section longitudinally disposed between the first section and the second section;
wherein the first section and the second section are radially sized to fit within the cavity such that fluid is prevented from passing within the cavity between each of the first section and the second section and the housing; and
wherein the intermediate section is radially sized to be smaller than the first section and the second section such that the fluid is allowed to flow radially about the intermediate section and the housing, between the first section and the second section.

3. The transmission fluid circuit of claim 2 ,
wherein the biasing device continuously applies a bias force to the spool in a first longitudinal direction;
wherein the actuator acts on the spool in a second longitudinal direction, opposite the first longitudinal direction;
wherein the spool moves in the second longitudinal direction from the first position to the second position when an actuator force resulting from the activated smart material acting on the spool in the second longitudinal direction exceeds the bias force of the biasing device acting on the spool in the first longitudinal direction; and
wherein the spool moves in the first longitudinal direction from the second position to the first position when an actuator force resulting from deactivated smart material acting on the spool in the second longitudinal direction is less than the bias force of the biasing device acting on the spool in the first longitudinal direction.

Assignees

• Gm Global Tech Operations Llc
• Dynalloy Inc

Inventors

• Gao Xiujie
• Johnson Nancy L
• Semel Ronald R
• Brown James Holbrook

Classifications

• F16H57/0413 Primary

  Controlled cooling or heating of lubricant; Temperature control therefor · CPC title

• F01M5/007

  Thermostatic control · CPC title