摘要:
A pressure reducing valve and a continuously variable transmission comprising an output pressure feedback loop operatively connected to provide proportional control of an output pressure of a flow of fluid passing through the pressure reducing valve in response to an input signal applied to a pilot stage control valve of the pressure reducing valve from an external source. The pressure reducing valve includes a main stage two-way spool valve having a valve body and a valve spool movable within the valve body in response to an imbalance of forces on the valve spool. The valve body has a supply port for receiving pressurized fluid from a source of constant hydraulic pressure and a load port for communicating a load pressure and flow from the spool valve to an actuator of the secondary pulley of the transmission to maintain transmission belt tension while preventing or minimizing belt slippage. The open area of the load port is dependent on the position of the valve spool within the valve body.
摘要:
A continuously variable transmission (CVT) with adjustable width pulleys has its belt tension and ratio controlled by an electronic-hydraulic system. The CVT also has a fluid-cooled clutch on the output pulley shaft. The engine speed, transmission output speed, throttle position, and gearshift position are sensed, and signals representing this information are passed to a computer. The computer provides set point signals denoting desired engine speed, line pressure, and clutch cooling condition to a control system. An electromechanical valve assembly regulates fluid flow to the CVT primary sheave, to control CVT ratio as a function of the computer provided set engine speed signal. A second electromechanical valve assembly controls the line pressure in the hydraulic system, which is applied to the secondary pulley to maintain belt tension, as a function of the set pressure signal provided by the computer. A solenoid-operated valve, regulated by the control system, either returns waste fluid from the second valve assembly directly to sump, or passes the fluid to the clutch when cooling is indicated.
摘要:
A continuously variable transmission, and particularly a control arrangement thereof and a method for recovering belt slippage in the transmission, are disclosed. A source of hydraulic pressure is operatively connected for driving each of the hydraulically operated actuators for axially movable sheaves of primary and secondary pulleys of the transmission. A hydraulic pressure control loop controls the hydraulic pressure applied to the actuator of the secondary pulley as a function of the load of the device being driven on the transmission and the pitch radius of the secondary pulley. An output speed control loop controls the output speed of the transmission driving the device to be driven during normal operation of the transmission. Preferably, the output speed control loop may be set to control the output speed at a constant value for driving an aircraft electric generator. A belt speed matching loop overrides the output speed control loop for adjusting the transmission ratio when a condition of belt slipping is detected to recover from belt slipping.
摘要:
In an inverting system, a reference V.sub.REF is coupled to an input of a predictor. The predictor has an output V.sub.P and a transfer function T.sub.P. An inverter of the inverting system has a pulse width modulator, a filter, and a transfer function T.sub.I. The transfer function T.sub.P is substantially equal to 1/T.sub.I. The inverter has an output V.sub.C, and the inverter is coupled to the output V.sub.P so that V.sub.C =V.sub.REF T.sub.P T.sub.I =V.sub.REF. In this manner, the output of the inverter tracks the reference without phase error.
摘要:
An air driven turbine having variable pitched blades is provided that includes a pitch change mechanism and associated control circuits for automatically adjusting the pitch of the blades during either rotating or non-rotating operational modes of the air driven turbine. The pitch control mechanism includes a resettable overspeed protection device which is directly actuated by an overspeed condition of the turbine and operates independently from the pitch change mechanism to move the blades to a failsafe, feathered, or coarse pitch, low speed position. The pitch control mechanism utilizes a linear actuator in the form of an acme screw drive. The air driven turbine includes a ball ramp thrust bearing for attaching the blades to a hub of the turbine in such a manner that during rotation of the turbine actuation loads on the pitch change mechanism are reduced. The control circuits utilize simple on-off switching circuits for controlling blade pitch, thereby eliminating the need for more complex PID type control functions.
摘要:
The problem of filtering DC power on a DC bus (46) in an electrical power generating system (10) is resolved using an active damper circuit (44). The active damper circuit (44) comprises a capacitor (CD) and a switching circuit (70) for alternately switching the capacitor (CD) into and out of parallel relationship with the DC bus (46).
摘要:
In a control (100) for a variable displacement hydraulic motor (12) having an electrically controlled hydraulic servo valve (14) for controlling the displacement of a hydraulic motor by varying position of a wobbler (28) in response to a servo valve control signal, a velocity transducer (72), coupled to a shaft (30) driven by the motor, for providing a velocity signal representative of the velocity of the shaft, and a wobbler position sensor (84), coupled to the wobbler, for producing a wobbler position signal indicative of the position of the wobbler, an improvement in accordance with the invention includes a controller (100) for producing the servo valve control signal as a function of a wobbler position command specifying a position of the wobbler wherein the wobbler position command is a function of at least one of the velocity signal representative of the velocity of the shaft and the wobbler position signal.
摘要:
A continuously variable transmission and method for preventing transmission belt slippage in the case of a sudden increase in load torque on the transmission involves both inserting a lag in the transmission to allow the control loops time to respond to the sudden increase in load torque and speeding up the responses of the control loops in response to the sudden increase in load torque. The transmission is used to drive an aircraft electrical generator at a constant speed in the disclosed embodiment.
摘要:
An inverter system (10) in accordance with the invention includes an electrical load (R,L) having a direct current source (E) for providing direct current to at least one pair of inverter switches Q.sub.1 and Q.sub.2 with the at least one pair of switches being switched between conducting and non-conducting states to control a direction of flow of current pulses between the direct current source and the electrical load to cause the flow of alternating current through the electrical load; a source of a voltage reference (V.sub.ref) representing a desired form of the alternating current to flow through the electrical load; an error control signal generator (24) having a first input coupled to the electrical load and a second input coupled to the voltage reference for generating on an output (26) an error control voltage representing a difference between the first and second inputs; and an inverter controller (16), coupled to the output of the error control signal generator and to the inverter, for controlling a frequency of switching of the at least one pair of switches in response to the error control voltage to produce current pulses flowing through the electrical load occurring at a variable frequency which provides the alternating current flow through the electrical load.
摘要:
The problem of controlling overspeed and/or oscillation of a variable displacement hydromechanical actuation system is solved by a multi-stage flow regulating valve (18) which includes a valve body (20, 22) having a fluid inlet (24) and a fluid outlet (26) defining a flow path (A,B) through the valve body. A first stage valve piston (30) is reciprocally mounted within a cylinder (28) in the valve body (20) in the flow path between the inlet and the outlet for restricting fluid flow in response to a first range of incoming fluid pressure. The first stage piston (30) has an inlet orifice (34) exposed to the incoming fluid and an outlet port (36) in registry with the outlet (26) of the valve body (20). A second stage valve piston (44) is reciprocally mounted within the first stage piston (30) and has an orifice plate (46) for covering the inlet orifice (34) of the first stage valve piston (30). The orifice plate has smaller orifices (48) for further restricting fluid flow through the valve body. The first stage piston is loaded by a spring (38) defining a first range of incoming fluid pressure and the reference pressure on the second stage valve piston defines a second range of incoming fluid pressure to provide a distinct multi-level range of regulating pressures.