Machine element or mechanism – Rotary member or shaft indexing – e.g. – tool or work turret – Preselected indexed position
Patent
1988-10-26
1991-04-09
Herrmann, Allan D.
Machine element or mechanism
Rotary member or shaft indexing, e.g., tool or work turret
Preselected indexed position
74861, 74866, F16H 6112, F16H 6116
Patent
active
050054457
DESCRIPTION:
BRIEF SUMMARY
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a national phase application corresponding to PCT/EP87/00220 filed 23 Apr. 1987 and based, in turn, upon an application filed in Luxembourg as PCT/EP86/00261 filed 2 May 1986 under the International Convention.
This invention relates to an electric-hydraulic control for an automatic transmission of the type in which a selecting slide serves at least for the selection of the neutral position (N), as well as the forward drive (D) and the reverse drive (R), an electronic control device is connected to a sensor for detecting the gear output speed, solenoid valves, kept in neutral position by spring force, a pressure-medium source, pressure-control valves and switch valves and dampers for the actuation of gear shifting couplings and brakes, as well as safety mechanism to prevent shifting into the R-gear when the forward-drive speed is too high.
BACKGROUND OF THE INVENTION
From the point of view of safety, in the case of automatic transmissions there are known devices which prevent a shifting into reverse gear through the setting of the selecting slide or manual valve in the position R by the driver when there is an excessively high driving speed and the vehicle rolls fowardly too quickly. Such devices are necessary in spite of the increased structure involved, in order to avoid damage in the transmission line, primarily in the gears, in the case of impermissible shifting into reverse gear.
In a known automatic transmission 4HP22 with an electronic-hydraulic control--ATZ 85 (1983) pages 401 to 405--such an inadmissible shifting is prevented by providing an additional solenoid valve and an additional reverse-speed safety valve especially designed for this purpose.
This arangement has proven to be suitable, since shifting of the manual valve into reverse does not lead to shifting in the transmission as long as the vehicle continues to rolls forwardly at a speed of over 8 km/h. However, the device is relatively complex.
OBJECT OF THE INVENTION
It is the object of the invention to provide an improved electric-hydraulic control of simplified construction without impairing the safety function in the case of impermissible shifting into the R-gear.
SUMMARY OF THE INVENTION
This object is attained in accordance with the invention by providing a solenoid valve and a hydraulic switch valve, both of which are necessary also for other gear selection operations. The solenoid valve is either immediately switched on by moving the manual valve into the R-speed when the speed of forward motion falls below a definite speed, or when the speed is still to high the switching is discontinued. When the speed falls below an established value, the electronic control apparatus switches off the solenoid valve and thereby the switch valve is reset for the actuation of the R-speed clutch and the R-speed brake. The hydraulic switch valve can have a sleeve valve with four control pistons and a stop pin which is arranged to be axially slidable in a housing with a bore and nine annular spaces. The sleeve value is biased into an end position by the force of a compression spring arranged around the stop pin. The control pistons cooperate with the annular spaces to lead into the ducts or to vent them.
The first frontal annular space for the actuation with control pressure is connected with a first solenoid valve via control duct and a control valve as well as another duct. System pressure is supplied via the manual valve in the position (D) and a duct to the second annular space and a clutch in the position of the first gear through a duct with the sixth annular space and in the position (R) through a duct with the seventh annular space. From the third annular space ducts lead to a further switch valves and clutches. The fourth and the ninth annular space, as well as the spring space are vented. The fifth annular space is connected with a brake via a duct and a ball valve. The eighth annular space is connected to the clutch via a duct and a ball valve and to the brake via a ball
REFERENCES:
patent: 4246990 (1981-01-01), Strantz
patent: 4419909 (1983-12-01), Opperud et al.
patent: 4733582 (1988-03-01), Eggert et al.
patent: 4896568 (1990-01-01), Gierer
Dubno Herbert
Herrmann Allan D.
Ta Khoi Q.
Zahnradfabrik Friedrichshafen AG
LandOfFree
Electric-hydraulic control for automatic transmission does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Electric-hydraulic control for automatic transmission, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Electric-hydraulic control for automatic transmission will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2025804