Machine element or mechanism – Rotary member or shaft indexing – e.g. – tool or work turret – Preselected indexed position
Patent
1983-04-11
1986-04-29
Pate, III, William F.
Machine element or mechanism
Rotary member or shaft indexing, e.g., tool or work turret
Preselected indexed position
74866, B60K 4104, B60K 4118
Patent
active
045849056
DESCRIPTION:
BRIEF SUMMARY
STATE OF THE ART
The present invention relates generally to the regulation of hydraulic pressure during gear changes in automotive automatic transmissions, and more particularly to an improved method and apparatus for hydraulic pressure regulation which keeps the slippage time constant, regardless of the type of gear change involved, and sets the hydraulic pressure in each instance to a value which is optimum in terms of both equipment wear and passenger comfort.
In known automatic transmissions, gear changes are performed at specific combinations of engine load (gas pedal position) and vehicle speed. In an electronic gear control system, these switching points are programmed in fixed form as characteristic gear changing curves. The frictionally engaged elements such as clutches or brakes, which are released or closed to effect the changing of the gear, are generally actuated hydraulically. The pressure in the frictionally engaged elements, which must be adapted to the engine torque at a given time, must not be excessively low, because then the slippage time, that is, the time during which the parts of the elements which effect the frictional engagement are sliding on one another, becomes too long. There would be excessive wear and heat, which causes the destruction of the frictional elements. On the other hand, the pressure must not be too high, because otherwise passenger comfort suffers from an excessive jolt while changing gears. From German Disclosure Document DE-OS No. 29 31 744, a method and apparatus for control of gear changing under load in a stepped gear transmission are known, in which the actuation force for the elements which function by frictional engagement is established by means of a hydraulic apparatus, which generates four pressure stages. The disadvantage in this known apparatus is that the pressure adaptation is effected only in some operating ranges, so that it may sometimes be inexact.
ADVANTAGES OF THE INVENTION
The method according to the invention and having the hydraulic pressure set proportional to the sum of the engine torque and the product of the engine speed and a constant factor and the apparatus according to the invention and having the adjusting elements, for actuating frictionally engaged elements, the adjusting elements being responsive to the sum of an engine torque signal and a multiple of an engine speed signal have the advantage over the prior art that the correct pressure is established for every gear changing point, and the slippage time remains constant for all the gear changing points. The gear changes are effected optimally in terms of both wear and comfort.
By means of the use of a pair of pressure regulators advantageous further embodiments of and additional improvements to the method and the apparatus are attained. As a result of the specialized embodiment of the stepped slide valve and regulating slide valve, only two pressure regulators are required for actuating all the frictionally engaged elements.
DRAWING
The apparatus according to the invention is shown in the drawing and will be explained in greater detail in the following description. FIGS. 1-3 show three embodiments of the apparatus in accordance with the invention with respect to changing gears, and FIG. 4 is a section taken through a hydraulic apparatus for generating various pressures, which are transmitted to the actuation members for the frictionally engaged elements.
DESCRIPTION OF THE EXEMPLARY EMBODIMENTS
Automatically shiftable transmissions in motor vehicles include a hydrodynamic converter or clutch driven by an internal combustion engine of the vehicle, which is followed by at least two sets of planetary gears which can be selectively shifted by means of clutches or brakes into the flow of power between the engine and the output of the transmission or the driveshaft of the vehicle. In order to actuate these frictionally engaged elements which effect the shifting operation, that is, which shift some transmission elements out of the flow of power and others into it, actuation e
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Bosch, Automotive Handbook, 1976, p. 321.
Eschrich Gerhard
Muller Alfred
Sauer Joseph
Schreiber Achim
Novais David
Pate III William F.
Robert & Bosch GmbH
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