摘要:
A control apparatus for a hydraulically operated transmission for a vehicle has a control circuit portion for a lockup clutch and a solenoid valve for controlling a clutch which is engaged in a particular drive range. In another drive range in which the clutch is not engaged, an output pressure of the solenoid valve is inputted to the control circuit portion. A changeover valve can be switched between a first position in which a first oil passage to be connected to an output side of the solenoid valve in the drive range and a second oil passage to be communicated with the control circuit portion are brought into communication with each other, and a second position in which this communication is shut off. The changeover valve is switched to the first position by a hydraulic oil pressure which is generated at the time of establishing a predetermined transmission train other than the first-speed transmission train. An input oil passage inputs the first signal pressure to urge the changeover valve to the first position in interlocking with switching of the changeover valve to the first position. The first signal pressure is maintained to a constant pressure without influence by speed changing.
摘要:
A hydraulic control unit for an automatic transmission having a plurality of power transmitting paths and a plurality of engaging clutches and/or brakes for selecting any one of the transmitting paths to set a gear position. The unit comprises a regulator valve for producing a line pressure, an operating pressure control valve for producing an operating pressure supplied to the engaging clutch or brake by regulating the line pressure from the regulator valve, and a line pressure switching valve for making the line pressure produced by the regulator valve low at a specified gear position when a target operating pressure set by the operating pressure control valve is lower than a specified value and making the line pressure high when the target operating pressure is higher than the specified value.
摘要:
A hydraulic control system for a vehicle automatic transmission, in which hydraulic pressure of a pressure source is supplied through a corresponding one of hydraulic lines to each of engaging means when achieving different gear ratios, and a plurality of shift devices are coupled respectively to the lines for switching supply and discharge of the hydraulic pressures to and from the respective engaging means in accordance with running conditions of the vehicle. At least one valve device is coupled to at least one of the lines. The valve device is movable between a supply position where hydraulic pressure is suppled to a corresponding one of the engaging means and a discharge position where the hydraulic pressure suppled to the engaging means is discharged. A plurality of pressure detectors respectively detect hydraulic pressures in the respective hydraulic lines. When the number of engaging means having applied respectively thereto hydraulic pressures higher than their respective predetermined values is equal to or greater than a predetermined value, a switching device switches the valve devices to move same to its discharge position, thereby avoiding locking of the transmission mechanism. A pressure regulating valve device is interposed between the pressure source and a high speed engaging means which can achieve shifting into a high gear ratio.
摘要:
A hydraulic oil pressure changeover mechanism for switching an input pressure to a solenoid valve between a high pressure and a low pressure. The changeover mechanism is made up of: a pressure reduction valve to be switched between an operating condition for outputting a low hydraulic oil pressure and a non-operating condition for outputting a high hydraulic oil pressure; a changeover valve to be switched between a low-pressure position for inputting an output pressure from the pressure reduction valve to the solenoid valve and a high-pressure position for inputting a hydraulic oil pressure to be supplied without passing through the pressure reduction valve to the solenoid valve; and a control valve to be switched between a first position for outputting a first signal pressure to switch the pressure reduction valve to the non-operating condition and a second position for outputting a second signal pressure which operates in a direction to switch the changeover valve to the low-pressure position. The changeover valve can be switched to the low-pressure position when the second signal pressure and a third signal pressure are operated on the changeover valve.
摘要:
A changeover valve is provided on an upstream side of solenoid valves for hydraulic engaging elements. The changeover valve is urged to the closed position by the hydraulic oil pressure of a plurality of hydraulic engaging elements which are concerned with the speed changing. At the time of failure in which three or more of the hydraulic engaging elements are simultaneously engaged, the changeover valve is changed over to the closed position to thereby lower the hydraulic oil pressure in the hydraulic engaging elements on the downstream side of the changeover valve, whereby the simultaneous engagement is prevented. In the closed position, a hydraulic oil pressure of a predetermined pressure is inputted to the changeover valve via an oil passage. The chattering of the changeover valve is thus prevented even if the hydraulic oil pressure in the hydraulic engaging elements may be lowered.
摘要:
An automatic transmission on an automobile has an input shaft, an output shaft, a plurality of power transmitting paths disposed between the input and output shafts for establishing respective gear positions, and a plurality of engaging elements for selecting one of the power transmitting paths at a time. A shift controller disengages a previous-position engaging element and engages a next-position engaging element to switch from one of the power transmitting paths to another for thereby effecting a shift from a previous gear position to a next gear position. The shift controller provides a plurality of previous-position stages for controlling the previous-position engaging element with respective different characteristics to vary forces to disengage the previous-position engaging element in each of the gear positions, and a plurality of next-position stages for controlling the next-position engaging element with respective different characteristics to vary forces to engage the next-position engaging element in each of the gear positions. The shift controller executes the previous-position stages and the next-position stages to effect a shift between gear positions according to a change in the rotational speed of the input shaft, and executes all or selected ones of the previous-position stages and the next-position stages successively in order.
摘要:
A hydraulic pressure control apparatus for an automatic transmission includes brakes and clutches to be engaged for selectively establishing gear positions in response to a controlling hydraulic pressure from a hydraulic pressure source. Two solenoid-operated valve assemblies are disposed in a hydraulic passage between the hydraulic pressure source and the brakes and clutches. The solenoid-operated valve assemblies are independently operable in response to respective control signals for controlling the supply of the controlling hydraulic pressure from the hydraulic pressure source to the brakes and clutches.
摘要:
A hydraulic relief valve according to the invention comprises; a housing having a clutch port communicating with a hydraulic chamber of a given hydraulic clutch and a drain port communicating with a drain, a spool inserted in the housing and being movable between an operational position at which the clutch port is isolated from the drain port and a relief position at which the clutch port communicates with the drain port, and biasing means to push the spool toward the operational position. The housing further includes an up-shift port communicating with a hydraulic chamber of an up-shift clutch which is engaged when the speed range is shifted up from the given speed range and a down shift port communicating with a hydraulic chamber of a down-shift clutch which is engaged when the speed range is shifted down from the give speed range. The hydraulic pressure in the chamber of the up-shift clutch is supplied into said housing through the up-shift port to push the spool toward the relief position when the speed range is shifted up. The hydraulic pressure in the chamber of the down-shift clutch is supplied into the housing through the down-shift port to push the spool toward the relief position when the speed range is shifted down.
摘要:
A shift control apparatus controls the shifting of a transmission by selecting one power transmitting path at a time from a plurality of paths respectively having different speed reduction ratios. At least one power transmitting path is provided with a one-way clutch and an engine-brake clutch is included in the plurality of paths. The one-way clutch can be locked by the engine-brake clutch. An engine-brake clutch control valve is provided for controlling the engine-brake clutch. Two solenoid valves are provided for controlling the engine brake clutch control valve. When one of the two solenoid valves fails and is inactivated, the other solenoid valve is used to cause the engine-brake clutch control valve to engage the engine-brake clutch.