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Patent Issued for Variator Multiplex Valve Scheme for a Torroidal Traction Drive Transmision

May 28, 2014



By a News Reporter-Staff News Editor at Journal of Engineering -- A patent by the inventors Long, Charles F. (Pittsboro, IN); Weber, Darren J. (Indianapolis, IN); Fuller, John W. E. (Preston, GB), filed on December 14, 2011, was published online on May 13, 2014, according to news reporting originating from Alexandria, Virginia, by VerticalNews correspondents.

Patent number 8721494 is assigned to Allison Transmission, Inc. (Indianapolis, IN).

The following quote was obtained by the news editors from the background information supplied by the inventors: "Torroidal traction drive automatic transmissions may typically include a variator and one or more gear sets. Within each gear set, the variator may generally control a direction, e.g., positive or negative, and magnitude of torque transferred by a power plant to one or more loads. Structures and techniques for controlling fluid flow to the variator during various operating conditions of the transmission must therefore be designed and implemented."

In addition to the background information obtained for this patent, VerticalNews journalists also obtained the inventors' summary information for this patent: "The present application discloses one or more of the features recited in the appended claims and/or the following features which alone or in any combination, may comprise patentable subject matter.

"An apparatus for controlling fluid flow to a variator in an automatic transmission. The variator may be responsive to separate high and low pressure fluids to control an output torque of the variator. The apparatus may comprise a first trim valve responsive to a first control signal to supply a first fluid at a fluid outlet thereof, a second trim valve responsive to a second control signal to supply a second fluid at a fluid outlet thereof, a variator switching sub-system controllably supplying the high pressure fluid and the low pressure fluid to the variator, and a multiplex valve fluidly coupled to the outlets of the first and second trim valves, the multiplex valve supplying the first fluid supplied by the first trim valve as the high pressure fluid to the variator switching sub-system during at least one predefined operating condition of the automatic transmission and otherwise supplying the second fluid supplied by the second trim valve as the high pressure fluid to the variator switching sub-system.

"The apparatus may further comprise a control circuit including a memory having instructions stored therein executable by the control circuit to produce the first and second control signals. The at least one predefined operating condition may comprise at least one of a fault condition associated with the automatic transmission and a cold start condition.

"The multiplex valve may comprise a spool having a stroked operating state and a destroked operating state. The multiplex valve may supply the first fluid as the high pressure fluid to the variator switching sub-system in one of the stroked operating state and the destroked operating state, and the multiplex valve may supply the second fluid as the high pressure fluid to the variator switching sub-system in the other one of the stroked operating state and the destroked operating state. The apparatus may further comprise a control valve responsive to a third control signal to control the multiplex valve to the stroked operating state and to a fourth control signal to control the multiplex valve to the destroked operating state. The apparatus may further comprise a control circuit including a memory having instructions stored therein executable by the control circuit to produce one of the third and fourth control signals to control the control valve to the other one of the stroked operating state and the destroked operating state during the at least one predefined operating condition, and the at least one predefined operating condition may comprise at least one of a fault condition associated with the automatic transmission and a cold start condition.

"The apparatus may further comprise a regulator valve fluidly coupled by the multiplex valve to a reference pressure during the at least one predefined operating condition. The regulator valve may also be fluidly coupled to a main fluid passageway that is further fluidly connected to a fluid inlet of the first trim valve. The regulator valve may be responsive to the reference pressure to regulate fluid pressure in the main fluid passageway to a fixed pressure main fluid during the at least one predefined operating condition. The fluid outlet of the first trim valve may be fluidly coupled by the multiplex valve to the variator switching sub-system during the at least one predefined operating condition. The first trim valve may be responsive to the first control signal to supply the first fluid as the high pressure fluid based on the fixed pressure main fluid during the at least one predefined operating condition. The main fluid passageway may be further fluidly coupled by the regulator valve to a fluid inlet of the second trim valve. The second trim valve may be responsive to the second control signal to supply the second fluid to the multiplex valve based on the fixed pressure main fluid during the at least one predefined operating condition. The multiplex valve may block the fixed pressure second fluid from the variator switching sub-system during the at least one predefined operating condition. The variator may have at least one roller between a first torroidal disk coupled to an input of the automatic transmission and a second torroidal disk coupled to an output of the automatic transmission. The variator may be fluidly coupled to an endload fluid passageway. The endload fluid passageway may define therein an endload pressure corresponding to a pressure load on the first and second torroidal disks required to keep the first and second torroidal disks from slipping. The endload fluid passageway may be fluidly coupled to the multiplex valve. The multiplex valve may fluidly couple the endload fluid passageway to the main fluid passageway to thereby supply the fixed pressure main fluid to the endload fluid passageway during the at least one predefined operating condition.

"The apparatus may further comprise a control circuit including a memory having instructions stored therein executable by the control circuit to produce the other one of the third and fourth control signals to control the control valve to the one of the stroked operating state and the destroked operating state during operating conditions other than the at least one predefined operating condition.

"The apparatus may further comprise a regulator valve fluidly coupled by the multiplex valve to the fluid outlet of the first trim valve during operating conditions other than the at least one predefined operating condition. The regulator valve may also be fluidly coupled to a main fluid passageway that is further fluidly connected to a fluid inlet of the first trim valve. The first trim valve may be responsive to the first control signal to supply the first fluid to the fluid outlet of the first trim valve based on pressure of fluid in the main fluid passageway during the operating conditions other than the at least one predefined operating condition. The regulator valve may be responsive to the first fluid to regulate fluid pressure in the main fluid passageway during the operating conditions other than the at least one predefined operating condition. The main fluid passageway may be further fluidly coupled by the regulator valve to a fluid inlet of the second trim valve. The fluid outlet of the second trim valve may be fluidly coupled by the multiplex valve to the variator switching sub-system during the operating conditions other than the at least one predefined operating condition. The second trim valve may be responsive to the second control signal to supply the second fluid as the high pressure fluid based on fluid pressure in the main fluid passageway during the conditions other than the at least one predefined operating condition. The variator may have at least one roller between a first torroidal disk coupled to an input of the automatic transmission and a second torroidal disk coupled to an output of the automatic transmission. The variator may be fluidly coupled to an endload fluid passageway. The endload fluid passageway may define therein an endload pressure corresponding to a pressure load on the first and second torroidal disks required to keep the first and second torroidal disks from slipping. The endload fluid passageway may be fluidly coupled to the multiplex valve. The multiplex valve may fluidly couple the endload fluid passageway to a variable pressure fluid passageway of the variator such that fluid pressure in the endload fluid passageway is variably controlled by the variator during the operating conditions other than the at least one predefined operating condition.

"A method for controlling fluid flow to a variator in an automatic transmission, wherein the variator is responsive to separate high and low pressure fluids supplied by a variator switching sub-system to control an output torque of the variator, may comprise supplying a first fluid supplied by a first trim valve as the high pressure fluid to the variator switching sub-system during at least one predefined operating condition of the automatic transmission, and supplying a second fluid supplied by a second trim valve separate from the first trim valve as the high pressure fluid to the variator switching sub-system during operating conditions other than the at least one predefined operating condition.

"The first fluid supplied by the first trim valve to the variator switching sub-system as the high pressure fluid during the at least one predefined operating condition of the automatic transmission may be a variable pressure fluid. The variable pressure first fluid supplied by the first trim valve to the variator switching sub-system as the high pressure fluid during the at least one predefined operating condition may be derived from a main fluid, and the method may further comprise regulating pressure of the main fluid to a fixed pressure based on a fixed reference pressure during the at least one predefined operating condition.

"The fixed reference pressure may be ambient pressure.

"The second fluid supplied by the second trim valve to the variator switching sub-system as the high pressure fluid during the operating conditions other than the at least one predefined operating condition of the automatic transmission may be a variable pressure fluid. The variable pressure second fluid supplied by the second trim valve to the variator switching sub-system as the high pressure fluid during the operating conditions other than the at least one predefined operating condition may be derived from a main fluid, and wherein the method may further comprise modulating fluid pressure of the main fluid based on the first fluid supplied by the first trim valve during the operating condition other than the at least one predefined operating condition.

"The variator may have at least one roller between a first torroidal disk coupled to an input of the automatic transmission and a second torroidal disk coupled to an output of the automatic transmission, and the variator may have an endload fluid passageway defining therein an endload pressure corresponding to a pressure load on the first and second torroidal disks required to keep the first and second torroidal disks from slipping. The method may further comprise supplying a fixed pressure fluid to the endload fluid passageway during the at least one predefined operating condition. The method may further comprise fluidly coupling the endload fluid passageway to a variable pressure fluid passageway of the variator during the operating conditions other than the at least one predefined operating condition such that fluid pressure in the endload fluid passageway is variably controlled by the variator during the operating conditions other than the at least one predefined operating condition.

"The at least one predefined operating condition may comprise at least one of a fault condition associated with the automatic transmission and a cold start condition.

"Additional features and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of illustrated embodiments exemplifying the best mode of carrying out the invention as presently perceived."

URL and more information on this patent, see: Long, Charles F.; Weber, Darren J.; Fuller, John W. E.. Variator Multiplex Valve Scheme for a Torroidal Traction Drive Transmision. U.S. Patent Number 8721494, filed December 14, 2011, and published online on May 13, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&p=109&u=%2Fnetahtml%2FPTO%2Fsearch-bool.html&r=5436&f=G&l=50&co1=AND&d=PTXT&s1=20140513.PD.&OS=ISD/20140513&RS=ISD/20140513

Keywords for this news article include: Allison Transmission Inc.

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Source: Journal of Engineering


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