초록 ▼

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 t

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.

대표청구항 ▼

A control system for controlling the transmission fluid pressure in a transmission, comprising: means for developing an electrical signal having a characteristic which is adjustable; a supply of pressurized transmission fluid; means responsive to said pressurized transmission fluid and to said elect

A control system for controlling the transmission fluid pressure in a transmission, comprising: means for developing an electrical signal having a characteristic which is adjustable; a supply of pressurized transmission fluid; means responsive to said pressurized transmission fluid and to said electrical signal for producing a controlled transmission fluid pressure the level of which is determined by, and is proportional to, the characteristic of the electrical signal; and temperature sensing means for sensing the temperature of the transmission fluid, said means for developing an electrical signal being responsive to said temperature sensing means, for adjusting the characteristic of the electrical signal as a function of the temperature of the transmission fluid.