Machine element or mechanism – Rotary member or shaft indexing – e.g. – tool or work turret – Preselected indexed position
Patent
1989-02-24
1990-07-31
Diehl, Dwight
Machine element or mechanism
Rotary member or shaft indexing, e.g., tool or work turret
Preselected indexed position
475129, B60K 4106
Patent
active
049442023
DESCRIPTION:
BRIEF SUMMARY
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a National Phase application of PCT/EP87/00505 filed 7 Sept. 1987 and based upon Luxembourg application PCT/EP86/00517 of 9 Sept. 1986.
This invention relates to an electrohydraulic control for an automatically shiftable automotive transmission with at least two solenoid valves which are connected via control pressure lines with gear control valves, and these are connected with clutch valves and shock absorbers via system pressure lines in order to engage the clutches and wherein in order to shift into a gear the two clutches are engaged, whereby the clutch valves have an additional connection for the supply of a load-dependent modulation pressure.
FIELD OF THE INVENTION
A 4-speed automatic transmission with electronic-hydraulic control is known from two publications in ATZ 85 (1983) 6 pages 393 to 405. From FIG. 6 page 403 it is known that for instance second gear is engaged via two solenoid valves (MV 1, MV 2) and two gear control valves 1-2, 2-3, as well as two clutch valves C, C' and the thereto pertaining clutches C, C'. In the publication 4 HP 22 E of the ZF GETRIBE GMBH SAARBRUCKEN, Oil Circuit Diagrams, this electronic-hydraulic control is illustrated in detail and completed in FIG. 6. The gear-control- and clutch valves and their connection lines, as well as the dampers for the clutches C and C' are discernable.
Since particularly in a gear shift from the first to the second gear the highest rotational speed difference normally nust be compensated and the layout of the clutches has to be done in view of this possible difference and full load, rough gear changes occur frequently at zero- or partial loads.
OBJECT OF THE INVENTION
It is therefore the object of the invention to improve an electrohydraulic control as describe so that in the case of gear changes with high rotational-speed differences with a zero load or in the lower load range no rough transitions result at minimum expense.
SUMMARY OF THE INVENTION
This object is attained in that, for the closing of the clutches, the control pressure line, the system pressure line and the modulation pressure line connect a gear-control valve and a clutch valve with a damper and cooperate therewith in such a way that one clutch is closed with a delay.
While according to the state of the art both couplings are simultaneously engaged over the entire load range, it is possible to delay the closing of one coupling with simple means, so that a smoother load takeover, and thereby a smoother gear change, results. The additional engagement of the second clutch, delayed with respect to the engagement of the first clutch occurs depending on the load. Preferably the delayed engagement of the second clutch takes place at a lower load and thereby at a lower rotational speed difference. With this arrangement the invention is further developed in an advantageous manner. Since in an automatic transmission, in addition to a good gear-change quality, the time required for a gear shift and also the wear of the couplings in the friction phase are of greatest importance, the synchronous or asynchronous engagement of the coplings depending on the load range is particularly advantageous, because the asynchronous engagement occurs only under partial- or zero load, when it is necessary for a quality gear shift.
From DE-B-26 59 353 a hydraulic control system is known wherein when shifting up for changing to a gear with high rotational speed difference (e.g. gear 1 to gear 2) the layout of the coupling for the full load takes place and independently from the actual load during the shifting-up operation and the timely delayed pressure build-up, two couplings (brakes C, C') are symmetrically filled with pressure medium. Only after the slip phase has been concluded, the coupling pressure from the first coupling (brake C) switches the coupling valve of the second coupling (brake C'), so that now the pressure build-up of this second coupling C' is slowed down in comparison to the first coupling, by means of a throttl
REFERENCES:
patent: 3559669 (1971-02-01), Dach
patent: 4674364 (1987-06-01), Shindo et al.
patent: 4718310 (1988-01-01), Shindo et al.
patent: 4727772 (1988-03-01), Samiya et al.
patent: 4811630 (1989-03-01), Heber
Automobiltechnische Zeischrift, vol. 85, No. 6, pp. 401-405; Jun. 1983.
Diehl Dwight
Dubno Herbert
Zahnradfabrik Friedrichshafen AG
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