Robert Boschgmbh

Alfred Muller

Manfred Schwab

Joseph Sauer

Achim Schreiber

Helmut Mohl

Gerhard Eschrich

Walter Stroh

Meinrad Feder

Heinz Leiber

Cornelius Peter

Rainer Burkel

Armin Czinczel

Dieter Schaller

Manfred Schab

The desired acceleration, a value required to determine shift points in an automatic transmission, is computed on the basis of the measured speed, output torque of the transmission, and the tractive resistance at rated load on a level road. Additionally, a shift which is otherwise indicated is suppressed when the computed output torque of the transmission in the new gear is less than the actual tractive resistance. Preferably an incremental value is added to the tractive resistance prior to comparison with the output torque in the new gear, so that hunting is prevented. The incremental resistance value, which is added to the tractive resistance, may be a constant or may vary as a function of speed.

Control apparatus for an automatic transmission

To control the pressure p of an operating fluid in an automatic transmission (12), the input speed and output speed (n.sub.T, n.sub.out) of the transmission is sensed, and the pressure (p) is so controlled by a control unit (21) that the transmission ratio which is actually coupled by the transmission, in view of the pressure set by the friction bands, is carried out in accordance with a predetermined timing function (i.sub.com), for example as stored in a read-only memory (ROM, 24). Change in shifting characteristics can be obtained, for example, by operator-selected different time-engagement relationships to obtain maximum passenger comfort or maximum acceleration, or intermediate relationships.

Automotive gearshift jolt minimization system

Method and apparatus for control of gear changing under load in a

The kickdown function for modifying the operation of an automatic transmission to make the higher power of a lower gear more extensively available is arranged to take place in response to several operating parameters only one of which is the operation of a kickdown switch and the normal gear pattern is restored likewise in response to any one of several parameters. The function is thus more flexibly adapted to driving conditions and avoids the excessive shifting between gear ratios that may result from more rigidly designed kickdown systems.

Control of the shift points of an automatic transmission for temporary

After the gear ratio of an automatic transmission has been increased in response to a braking operation the return to normal operation of the automatic transmission is controlled by logic circuits interconnecting threshold switches operated by the brake pedal and the accelerator pedal and by a read-only memory that stores a maximum engine speed for all values of vehicle speed so that the higher gear ratio is maintained until either the brake is released or the maximum engine speed is exceeded and then the return to normal transmission operation is further delayed until the accelerator pedal is again actuated. In one method, during the period of further delay the gear ratio continues at its raised value. In another embodiment the period of further delay begins with storage of the vehicle speed at the moment and proceeds with control of the transmission to maintain that speed. It is also possible to operate the system so as not to restore normal operation of the transmission after braking when there is only a slight depression of the accelerator pedal.

Method of controlling downshift after braking in automatic transmissions

To control transmission ratio of a continuously variable transmission connected to a combustion engine (e.g., for optimal fuel efficiency of a powered vehicle), effective diameter of pulleys is controlled in response to an electrical signal. A control signal suitable for comparison with hydrostatic pressure values is produced by a computing device based on input signals representing load, speed, and other operating conditions and based further on stored data representing engine characteristics. A control signal is conveniently used to control hydrostatic pressure by means of electromagnetically operated valves. Especially when pulsed valves controlled by digital electric signals are used, a reservoir is used to establish a steady hydrostatic pressure. Such control device is readily adapted to different engines by replacement of stored characteristic data.

Electronic control for a stepless vehicle transmission using a control

The time required for shifting gears from an old to a new gear and the jolt created by the shift is decreased by initiating a known overlap of disengagement of the friction elements of the old gear and engagement of the friction elements of the new gear at the time the hydraulic unit operating the friction elements of the new gear is completely filled. Since a voltage pulse occurs across the solenoid winding of the pressure regulator when the hydraulic unit is completely filled, the solenoid valve is monitored by a threshold circuit which responds to the pulse. The output of the threshold circuit sets a flipflop. The flipflop is reset in response to a gear shift initiation signal furnished by a microprocessor. The microprocessor samples the flipflop output to determine whether the hydraulic unit is completely filled and initiates the overlap portion of the gear shift when this is so.

Gear shift control in motor vehicles with automatic transmissions

The hydraulic regulating device for an automatic transmission having a selector valve for selecting a plurality of gear stages, includes a high pressure conduit, a working pressure conduit and a shift pressure conduit, a plurality of coupling elements assigned to respective gears, a single, pressure regulating valve electromagnetically controlled by a control signal to build up or decrease pressure in the shift pressure conduit, holding valves connected between the working pressure conduit and the shift pressure conduit, and shift control valves connected to the shift pressure conduit and cooperating with the holding valves to connect, in response to an increased gear, the coupling elements pertaining to the higher gear in a preselected gear stage, to the shift pressure conduit and, upon completion of the gear shift operation, to connect via the working pressure conduit the coupling elements to the high pressure conduit with the exception of the last actuated coupling element who remains connected to the shift pressure conduit.

Hydraulic regulating device for load operated gear shift systems

The automatic transmission control unit in a motor vehicle furnishes a signal which signifies that motor torque is to be decreased, thereby decreasing jolts or wear on friction elements in the transmission. In response to this signal, the input or output signals of a motor control unit, for example either an ignition control stage or an injection control stage, are changed in such a way that the motor torque will be decreased. Circuits for delaying ignition timing, shortening the pulse width of injection pulses, etc. are disclosed. The present invention is essentially an adapter unit so that the desired decrease in motor torque can be effected with the injection or ignition timing units already present in the motor vehicle.

Apparatus for decreasing jolts during gear shifts in automatic

The hydraulic regulating device for an automatic transmission system in motor vehicles having a plurality of hydraulic couplings, includes a single pressure build-up regulating valve and a single pressure decrease regulating valve and assigned to each coupling a solenoid operated directional control valve having its working port connected to the couplings, its pressure port connected via a switch-on reversing valve to the pressure build-up regulating valve, and its return port connected via a switch-off reversing valve to a return conduit; both reversing valves are controlled according to predetermined pressure levels on the coupling so that in the working position of the switch-on reversing valve the coupling is connected to a stable high pressure and when the coupling process is initiated by reversing the position of the directional control valve, the switch-off reversing valve connects the coupling element to the pressure decrease regulating valve.

Hydraulic regulating device for load shifted gears

To control transmission ratio of a continuously variable transmission connected to a combustion engine (e.g., for optimal fuel efficiency of a powered vehicle), effective diameter of pulleys is controlled in response to an electrical signal. A control signal suitable for comparison with hydrodynamic pressure values is produced by a computing device based on input signals representing load, speed, and other operating conditions and based further on stored data representing engine characteristics. A control signal is conveniently used to control hydrodynamic pressure by means of electromagnetically operated valves. Such control device is readily adapted to different engines by replacement of stored characteristic data.

The signal initiating a reduction of engine torque during gear shift is derived from a monitoring of the engine speed. Specifically, the decrease in torque is initiated when engine deceleration, as determined by the negative speed gradient, exceeds a predetermined value. The torque decrease can, as preferred, take place only if a gear shift occurs, or it may take place independent of gear shift in which case high decelerations caused, for example, by rapid application of the brakes, also cause the decrease.

Method and apparatus for controlling the torque of an internal

In first gear, a brake band prevents one gear of the planetary gearing of an automatic transmission from rotating. In second gear, a clutch causes this gear to rotate as a unit with the drive and driven shaft of the transmission. For an upshift under load, the clutch is engaged slowly, thereby decreasing the required brake torque. The brake force is therefore decreased at a corresponding rate. A switch having a movable contact is mounted so that the contact is moved in response to the reactive force created between the brake band and the gear box. This reactive force varies as a function of the brake force and also depends upon the direction of movement of the braked member. The switch is set to a threshold value which is substantially less than the brake force applied in first gear. At the freewheel point, that is the point at which the moment of the brake member changes direction, the brake force has been decreased sufficiently that the change in direction of the moment will cause the switch to pass the threshold value thereby generating a signal. This signal is processed to cause full disengagement of the brake. The switch will also pass the threshold value when, after complete disengagement of the brake, a change in direction of moment of the member occurs. At this point the brake is fully engaged in a downshift under load.

Gearshift method and apparatus

The invention pertains to a hydraulic control system for servos in automatic transmissions, which, in a known fashion, utilizes a main pressure valve to regulate the pressure within the control system and further utilizes a converter pressure valve to supply a hydrodynamic torque converter and the lubrication system. The servos (for example, the clutches) utilized in this type of automatic transmissions cooperate with electromagnetically actuated pressure regulating valves have a current-proportional response. These electromagnetic valves are actuated by electronic control signals generated by sensors which monitor various parameters during operation, making previously utilized sensors superfluous. By control of the pressure regulating valves the forward gear, the reverse gear or the neutral gear can be engaged in the simplest fashion. By means of a magnet valve associated with the main pressure valve the levels of pressure may be varied. It is also possible, via simple associated elements, to install an emergency system which during a failure of the electrical system allows the transmission to continue to operate.

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Leonberg, Germany

Alfred Muller