Abstract:
A control system for a torque converter includes a lockup clutch provided in the converter for connecting input and output shafts of the torque converter directly. The lockup clutch includes an engaging chamber and a releasing chamber. The control system further includes a lockup shift valve for selectively switching communication between a fluid line, having a predetermined pressure, and the engaging chamber and communication between the fluid line and the releasing chamber. A lockup control valve is provided for controlling a pressure difference between fluid pressures in the engaging chamber and the releasing chamber and a control valve is provided for controlling the lockup clutch so that it engages completely. A first on-off solenoid valve controls the lockup shift valve, a duty solenoid valve controls the lockup control valve, and a second on-off solenoid valve controls the control valve.
Abstract:
A valve (36) for controlling pressure supplied to a friction clutch (32) of an automatic transmission includes several valve spools (38,40,44) each formed with control lands located within a bore (42) opening to various ports (60,66,68,72,76,80) that are supplied selectively with line pressure depending upon the operating state of the transmission. The valve operates in a primed condition, whereby a predetermined low pressure is supplied continually to the friction clutch. The valve supplies the clutch with a higher pressure that operates to stroke the clutch cylinder and friction element and thereafter regulates clutch pressure in accordance with changes in pressure in one of the ports. The clutch is stroked rapidly because the valve provides a relatively unrestricted supply of pressurized fluid through one of its inlet ports. After the clutch free-pack clearances are taken up, the valve restricts the clutch stroke against a cushion spring by opening the clutch cylinder to an orificed supply circuit. A delayed response to a change in operating state of the valve is minimized such that the control lands of the valve spools do not fully open line pressure supplied to the valve.
Abstract:
A control system/method for controlling the shifting of automated mechanical transmission systems (10) is provided. The control system/method (FIG. 4 ) defines the synchronous window ((OS*GR.sub.T)+X.gtoreq.IS.sub.E >(OS*GR.sub.T)-Y) for jaw clutch engagement (for shifts other than compound upshifts) where X and Y are each greater than zero and the total synchronous window (X+Y) equals the greater of a function (fGR.sub.T) of the numerical value of the target ratio (GR.sub.T) or a minimum value ((X+Y) min).
Abstract:
An automatic transmission control system couples frictional coupling element, such as a low reverse brake, so that the frictional coupling element provides different torque transmissive capacities in a reverse gear and a first gear in which engine braking is available. The system includes a pressure regulator which regulates a coupling pressure, by which the frictional coupling element is coupled and which is controlled and gradually supplied to the frictional coupling element, during a shifting of the automatic transmission to a reverse gear. The pressure regulator is disabled from regulating the coupling pressure in the reverse gear.
Abstract:
A control apparatus for a hydraulically operated vehicular transmission has a plurality of hydraulic engaging elements including a first hydraulic engaging element which is kept engaged in a plurality of transmission trains. The control apparatus has an accumulator which is connected, via a branched oil passage, to a working oil passage which is communicated with the first hydraulic engaging element. It also has a control valve which is disposed in the branched oil passage and which can be moved between a first position in which an upstream portion of the branched oil passage on a side of the first hydraulic engaging element and a downstream portion of the branched oil passage on a side of the accumulator are brought into communication with each other and a second position in which the communication is shut off. It further has an oil discharge passage which is connected to a second hydraulic engaging element when the second hydraulic engaging element is disengaged. This oil discharge passage is arranged to be connected to the downstream portion of the branched oil passage in the second position of the control valve.
Abstract:
An oil pressure control system for an automatic transmission for executing a downshift by disengaging a first frictional engagement element and engaging a second frictional engagement element. At a latter stage of a shift, the first frictional engagement element has its torque capacity increased by raising its oil pressure temporarily. After this, if a synchronization substantially reaching the revolution number at a gear stage after the downshift is detected, the first frictional engagement element has its torque capacity gradually dropped by dropping the oil pressure thereof gradually, and the second frictional engagement element has its oil pressure abruptly raised.
Abstract:
An automobile automatic transmission shift control system, for causing a specific gear shift by unlocking a first frictional element with a simultaneously with locking a second frictional element, discharges locking pressure from the first frictional element in such a way that the locking pressure is throttled after it has dropped below a specified level of pressure.
Abstract:
A hydrokinetic, multiple-ratio torque converter transmission mechanism having a simplified valve system with variable force solenoids for controlling line pressure as well as ratio shifts, a simplified clutch-and-brake hydraulic circuit with separate fluid pressure feed and exhaust passages, a common accumulator arrangement for controlling each of two ratio upshifts and a simplified brake servo mechanism having the dual function of establishing a torque reaction point for each of two distinct transmission ratios.
Abstract:
In a certain speed stage shifting of an automatic transmission of a vehicle including a speed change gear mechanism including rotary members such as gears and gear carriers and hydraulically operated friction engaging brakes and clutches adapted to provide various speed stages according to selective engagement and disengagement of the friction engaging brakes and clutches, the servo oil pressure of a first friction engaging brake is immediately lowered down to a stand-by pressure marginally higher than a threshold pressure bordering non sliding and sliding of the first friction engaging brake at the start of a change-over of a second friction engaging brake is and then, when a substantial change-over of the second friction engaging means started, the servo oil pressure is further lowered across the threshold pressure and thereafter periodically lowered by a decrement the magnitude of which may desirably be increased along with a lapse of time.
Abstract:
An electronic control is provided for controlling the drive speed of a supplemental drive relative to an engine driven main drive of a vehicle. A fluid pump driven by the engine provides pressurized fluid flow. The supplemental drive is driven by the pressurized fluid. A main drive sensor senses the speed of the main drive and responsively produces a main drive speed signal. A command knob is provided for selecting a desired speed relationship between the main and supplemental drives. A knob sensor senses the position of the command knob and responsively produces a modifier signal. A modifier circuit receives the main drive speed and modifier signals and responsively produces a modified main drive speed signal. A supplemental drive sensor senses the speed of the supplemental drive and responsively produces a supplemental drive speed signal. A processor produces an error signal responsive to a difference between received modified main and supplemental drive speed signals. The processor produces a first signal responsive to a product of the error signal and a preselected constant, produces a second signal responsive to an integral of the error signal, produces a third signal responsive to a derivative of the error signal and produces a pump control signal in response to a sum of the first, second, and third signals. An actuator receives the pump control signal and responsively adjusts the pump output.