Borg-warner Automotive Gmbh

William J Haley

Glenn E Swanson

Alan L Miller

Karl F Schneider

Philip J Mott

Guenter Neuman

A clutch cooling system for cooling a clutch used in combination with a continuously variable transmission including a pressure controlled spool valve having a housing defining a chamber, a spool movably mounted by a spring within the chamber, and a notch defined by the housing such that as the leading edge of the spool aligns with the notch a variable orifice is formed; a pressure controller means for adjusting the pressure applied to the remote end of the spool such that as the pressure applied to the remote end is reduced the spring decompresses causing the spool to traverse the housing and further causing the leading edge of the spool to pass along the notch thereby increasing the size of the variable orifice; a slot located within the spool that allows for minimum cooling flow when the spool valve variable orifice is closed; a cooling fluid feed line and a clutch cooling line extending from the chamber such that cooling fluid can flow from the cooling fluid feed line, into the chamber, through the orifice and into the clutch cooling line; and a electronic clutch control system for regulating clutch slippage wherein during a given amount of clutch slippage a predetermined electrical signal is sent to the pressure controller resulting in a given pressure being applied to the remote end of the spool.

System for cooling a starting clutch of a continuously variable

A system and several strategies for controlling a continuously variable transmission with an improved secondary servo arrangement in order to efficiently provide sufficient clamping forces under high torque conditions. The valving means allowing for the relative movement of the second variable pulley's movable sheave includes a valving arrangement operative to regulate the secondary apply pressure at or below the hydraulic source pressure and distinct from the primary line pressure. Control signals are developed to prevent belt slip and to efficiently launch a vehicle, maintain the necessary primary to secondary clamping force ratio in overdrive conditions, and avoid overpressurization of the secondary servo for many vehicle operating conditions.

Control system and strategies for a double acting secondary sheave servo

A continuously variable transmission includes an improved secondary servo arrangement in order to provide the necessary clamping forces for high torque conditions. The secondary servo includes a plurality of fluid chambers in order to allow an increase in the area for application of fluid pressure. Fluid conduits between the chambers permit communication of the fluid to the chambers to regulate the clamping force of the movable sheaves of the secondary variable pulleys.

Double acting secondary sheave servo for CVT

Double acting secondary sheave servo for a continuously variable

A dual capacity pump having at least two gear pump stages with a common fluid inlet passage, each pump stage having a discharge port, the discharge port for one stage communicating with a fluid pressure load through a flow delivery passage and the discharge port for the other stage communicating with the flow delivery passage through a one-way flow valve, and flow control valve means responsive to an operating variable for connecting the discharge side of the other stage to the common fluid inlet passage during operation in a first operating range of low driving speeds for the pump and to said flow delivery passage through the one-way flow valve during operation in a calibrated range of values for the operating variable.

Dual capacity fluid pump

A power train configuration for a continuously variable transmission includes a slippable start clutch located upstream of a belt and sheave system and a pair of non-dynamic forward-reverse clutches located down stream of the continuously variable component. The clutch capacities of the pair of forward-reverse clutches are marginally greater than the maximum torque capacity of the engine but marginally less than the torque at which the belt of the belt and sheave system slips.

Continuously variable transmission power train configuration

An adaptive clutch torque capacity control for an automotive vehicle clutch utilizing a dual area apply piston for engagement of the clutch plate for accurate control over a larger than normal torque range. The use of two piston areas allows one area to be controlled in a 'coarse' fashion, while the other piston area, which is generally a small area, provides a 'vernier' or fine adjustment control. The small area piston is controlled by an electronic closed loop for fine adjustment of any errors occurring in the 'coarse' control.

Dual clutch application area and control

When a pulse width modulated electrical signal is employed to operate an electro-mechanical device, such as a solenoid valve, in a transmission to produce a controlled fluid pressure whose level is proportional to the signal's duty cycle, proper operation at cold temperatures is ensured by varying the frequency of the pulse width modulated signal directly with the temperature of the transmission fluid. By decreasing the operating frequency when the transmission fluid is cold (at which time the fluid may thicken and become heavy since its viscosity will increase), the solenoid valve will be actuated slowly enough to effect flow control through the valve and adequate regulation of the fluid pressure.

Control system for controlling transmission fluid pressure

A control arrangement for a continuously variable transmission includes an electronic control system and a hydraulic control system. In the hydraulic control system three separate electromechanical control assemblies are used to regulate the pressure in the secondary sheave chamber (to hold the belt tension), the fluid flow to and from the primary sheave chamber (to regulate the CVT ratio), and to control the pressure in the apply line for the clutch chamber. The pump assembly of the hydraulic control system has a first output connection for providing fluid at line (high) pressure in the main line, and a second, low pressure output connection for providing fluid at a low pressure to satisfy the clutch cooling requirements. The high pressure and low pressure systems are essentially independent of each other.

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Ithaca, NY, United States of America

William J Haley