摘要:
A control system for an automatic transmission includes a first frictional engagement element and a second frictional engagement element; and a first hydraulic servo for controlling the application/release of the first frictional engagement element and a second hydraulic servo for controlling the application/release of the second frictional engagement element. A regulator valve regulates the oil pressure to the first hydraulic servo. A signal pressure is applied to the regulator valve to establish a predetermined gear stage by switching the applied/released states of the first frictional engagement element and the second frictional engagement element by feeding/releasing oil pressure to/from the first hydraulic servo and the second hydraulic servo. The regulator valve includes a valve member having: a first pressure receiving area to which is applied the feed pressure to the first hydraulic servo as a feedback pressure in a first direction; a second pressure receiving area to which is applied the signal pressure in a second direction opposite the first direction; a fourth pressure receiving area to which is applied the feed pressure to the second hydraulic servo in the first direction, in a shift wherein the first frictional engagement element is released while the second frictional-engagement element is applied; and a third pressure receiving area to which is applied the signal pressure in the second direction, for regulation of the oil pressure only during a shift.
摘要:
A shift control system of an automatic transmission sets a predetermined gear stage by applying a first frictional engagement element and releasing a second frictional engagement element. A pressure regulating mechanism regulates an oil pressure to be fed to or drained from the first frictional engagement element. A failure detector detects a failure of an apparatus to participate in the regulation and control of the oil pressure which is to be fed to or drained from at least one of the first and second frictional engagement elements. A gear stage inhibitor inhibits the setting of the predetermined gear stage if the failure is detected by the failure detector.
摘要:
A control system for use in an automatic transmission which includes a gear shift mechanism having first and second frictional engagement elements for establishing: a first gear stage with the first frictional engagement element being applied and the second frictional engagement element being released; and a second gear stage with the first frictional engagement element being released and the second frictional engagement element being applied. The control system, in turn, includes: a first oil passage for feeding an oil pressure to the first frictional engagement element; a second oil passage for feeding an oil pressure to the second frictional engagement element; and a first valve arranged in the first oil passage for regulating the oil pressure of the first oil passage. At the time of a shift from the first gear stage to the second gear stage, the oil pressure of the first oil passage is regulated by the first valve responsive to the oil pressure of the second oil passage. The control system further includes a second valve arranged in the first oil passage for selectively feeding or shutting off the oil pressure of the first oil passage to and from the first frictional engagement element.
摘要:
A shift control system of an automatic transmission for setting a predetermined gear stage by applying first frictional engagement means and releasing second frictional engagement means, comprising: a pressure regulating mechanism for regulating an oil pressure to be fed to or drained from the first frictional engagement means; a failure detector for detecting a failure of an apparatus to participate in the regulation and control of the oil pressure which is to be fed to or drained from at least one of the first and second frictional engagement means: and a gear stage inhibitor for inhibiting the setting of the predetermined gear stage if the failure is detected by the failure detector.
摘要:
A shift control system is provided for an automatic transmission having, connected in series, a secondary shifting unit, capable of being shifted between a high speed stage and a low speed stage, and a primary shifting unit which provides plural speed stages including a reverse speed stage. The secondary shifting unit can be set to the high speed stage upon a shift into reverse. The shift control system is equipped with a reverse range detector for detecting a shift from neutral to reverse range, a vehicle stop detector for detecting that vehicle is stopped, and a high speed stage command device for setting the secondary shifting unit at the high speed stage when, subsequent to a shift of the primary shifting unit into reverse, the vehicle is determined by a signal from the vehicle stop detector to have substantially stopped.
摘要:
A shift control system for shifting an automatic transmission from a predetermined gear stage to another by draining an oil pressure from predetermined frictional engagement element to release the same frictional engagement element and by feeding the oil pressure to another frictional engagement element to engage the same frictional engagement element while controlling the drain oil pressure of the frictional engagement element to be released and the engaging oil pressure to the frictional engagement element to be engaged. The shift control system includes an engine racing detector for detecting the racing of the engine while the transmission is being shifted in a clutch-to-clutch manner, and a hydraulic control circuit for controlling at least one of the drain oil pressure and the engaging oil pressure, on the basis of the degree of racing of the engine, as detected by the engine racing detector, such that the amount of racing of the engine falls within a predetermined range. Since the rotational state of the engine being shifted is controlled by hydraulic control of the frictional engagement elements participating in the clutch-to-clutch shift, it is possible to reliably prevent any excessive racing of the engine and to prevent reduction of output shaft torque due to the tie-up of the frictional engagement elements.
摘要:
A control system for an automatic transmission including a main transmission unit for setting a reverse stage and a plurality of forward stages and an auxiliary transmission unit connected in series to the main transmission unit and capable to be changed between two higher and lower stages. The control system comprises: a solenoid valve for outputting a signal pressure when at least the reverse stage and a predetermined one of the forward stages are to be set; a change-over valve for changing the signal pressure selectively into a signal pressure for setting the auxiliary transmission unit to a high gear stage and a signal pressure for controlling an engine braking state; and an engine braking control valve for controlling an engine braking frictional element at the predetermined forward stage into a released state in response to the signal pressure coming from the change-over valve. The acting state of the solenoid valve when the reverse stage is to be set and the acting state of the solenoid valve when the predetermined forward stage for making the engine braking ineffective is to be set are identical to each other.
摘要:
A control system is provided for servo hydraulic pressure in an automatic transmission having planetary gear mechanisms. First and second frictional engagement devices, whose servo pressures are reversed in feed/drain relationship between desired two high speed stages, are controlled by a shift valve and a directional control valve. The shift valve is switched by a first solenoid. The directional control valve is interposed in a servo hydraulic pressure feed/drain line communicating the shift valve with the first frictional engagement device and is controlled by a second solenoid. The first and second solenoids are controlled by an electronic control unit in accordance with a shift position detected by a detector, whereby the timings of feed or drain of the servo hydraulic pressures to or from the first and second frictional engagement devices are changed by predetermined relative amounts, respectively.
摘要:
A control system is provided for servo hydraulic pressure in an automatic transmission having planetary gear mechanisms. Shifting elements of the mechanisms can be connected to establish a different power flow in accordance with engagement or release of frictional engagement devices under the control of servo hydraulic pressure to achieve plural speed stages. The system comprises first and second frictional engagement devices engageable simultaneously in a reverse range, first and second servo pressure feed lines for feeding servo hydraulic pressure to the devices, a regulator valve disposed in the first line, a solenoid for controlling the valve, an electronic control unit for outputting a signal to the solenoid, and a detector for detecting shifting to the reverse range. The valve is controlled by the solenoid in accordance with an output from the unit upon detection of shifting to the reverse range by the detector, whereby engagement of the first device is coincided with that of the second device.
摘要:
A control system is provided for servo hydraulic pressure in a vehicular automatic transmission having planetary gear mechanisms. Shifting elements of the mechanisms can be connected to establish a different power flow in accordance with engagement or release of frictional engagement devices under the control of servo hydraulic pressure to achieve plural speed stages. The system comprises a servo pressure feed line for feeding, even in a non-running range, servo hydraulic pressure to at least one particular device out of plural frictional engagement devices which are caused to simultaneously engage in a reverse range of the transmission, a directional control valve disposed in the line to control feed or drain of the servo hydraulic pressure to or from said particular device through the line, and a solenoid valve for controlling the control valve to prevent the feed of the servo hydraulic pressure at vehicle speeds above a predetermined value.