DE2701298A1 - PROCEDURE FOR OPERATING VEHICLE DRIVES WORKING WITH POWER SHIFT TRANSMISSION AND ACTUATOR AND DRIVES WORKING ACCORDING TO THE PROCEDURE - Google Patents

Description

Mossey-Ferguson-Hanomag Ine & Co., Hanomagstrasse 9, 3000 Hannover-Linden

Process for the operation of vehicle drives working with power shift gears and converter and drive working according to the process

The invention relates to a method for operating with a powershift transmission and converter working vehicle drives and at the same time shows the drive order working according to the method, which is for all types of Vehicles, such as trucks, passenger cars, caterpillars or for agricultural tractors and in particular construction and earthmoving machines can be used. The well-known hydraulic powershift transmissions, which are preceded by a converter (torque converter), are designed so that the input power output by the drive motor into the transmission is regulated by means of the converter. This is necessary, for example, with tracked vehicles when the chain slips or when the speed should be regulated. In this case, the in the powershift transmission is regulated downwards. at Shifts under full load result in very high torque peaks

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of course all gear parts such as bearings, gears, clutches excessively load the powershift transmission, which leads to numerous malfunctions and premature wear. Another shortcoming of the known arrangements is that clutches switched under load have a speed difference over a longer period of time due to the high input torque. The product This speed difference and the torque result in switching work that is converted into heat. This amount of heat must be due to increased cooling capacity be eliminated. On the other hand, the amount of heat per unit area of the switching blades is limited, which means that only a limited amount of heat can be discharged, otherwise the coupling will be destroyed. After all, the individual couplings cannot be enlarged limitlessly because then the construction costs exceed the normal level and the installation space that is usually available is limited.

The object of the invention is that of the known drive arrangements to reduce detected high friction work and thus create the possibility of dimensioning such drive arrangements considerably smaller as well as special oil cooling devices, heat exchangers or the like to bypass, i.e. to reduce the required amount of flushing oil. This is achieved according to the invention in that after the start of the shift in the powershift transmission (for the purpose of changing direction or speed) the from Transmission torque to be absorbed is reduced by means of the converter and after the shift has taken place, i.e. after the frictional connection has been made Clutch, is increased again. According to the invention, the input torque of the powershift transmission is changed automatically by means of the converter as a function of the transmission shift pressure.

The arrangement can expediently be made in such a way that the actuating converter by means of a servomotor operated by the gear shift is controlled.

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In order not to disturb the normal work of the converter or the vehicle, the converter actuation can be applied for the purpose of overriding steering and / or braking pressure. The arrangement is made so that no or only a very short one during the switching process Dead time occurs and the tensile force is not interrupted or is only interrupted for a very short time.

The following is an exemplary embodiment of the invention based on a Drawing will be explained. Show:

Fig. 1 is a schematic representation of the torque converter

with the downstream powershift transmission,

Fig. 2

and 3 representations of the course of rotation over time

torque, switching pressure as well as input and output speed for a conventional arrangement in comparison for the arrangement according to the invention.

In Fig. 1, "A" as a whole denotes the torque converter which is driven by the engine via shaft 1, and "B" ^{denotes its switching and control part, and 11} C denotes the gearbox which is provided with the various gearboxes. The converter is actuated from the motor axis 1 via the flywheel 2, which is connected to the pump wheel of the converter 3. In the interior of the impeller 3 of the converter, the oil is circulated via the turbine, and the flow can be regulated by adjusting the guide vanes 4. The turbine 5 forms the output of the converter part "A", from which the powershift gear or multi-step gear ^{"C 1" is driven via an intermediate gear 6, in which a further gear step can be implemented, or directly.}

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2 y U

In the housing 7 of the gearbox are, depending on the application of the gearbox, various clutches housed, namely hydraulically switchable, with the help of which the desired gear stages can be realized.

The output shaft 8 of the powershift transmission leads to the usual drive or the machine to be driven. Usually in the powershift transmission actuates a hydraulic clutch 9 by a switching oil pump 10, which is driven by the impeller 3 of the converter via the intermediate drive 11, which is only shown schematically, via a pressure control valve 12 sends oil to the clutch 9. The oil distribution is carried out using a switching control device known per se, which is generally designated by 13 in FIG. 1.

In the arrangement according to the invention, the switching pressure is behind the Pressure regulating valve 12 as control pressure for actuating the torque converter A used. If the switching pressure collapses, as is usual with every switching process, when the control device 13 is actuated, then an electrical signal triggered by a hydraulic pressure transducer 14, which is shifted in time via a relay 15 as required and an electromagnet 16 controls. This releases via a directional valve 17, the movement of a servomotor 18 which controls the blades 4 of the converter adjusted in a corresponding sense. The directional valve 17, which controls the servomotor 18 can be carried out by the same pump 10 or, as shown in FIG. 1, by a second pump are acted upon with oil, which their drive from the gearbox 11 or the pump 10 derives. Of course, the relay 15 can also be omitted, if the system is set to a fixed time shift from the start.

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270 I.

In Fig. 2, the timing of switching pressure, torque and Input and output speed reproduced in those drives that work without the converter actuation according to the invention. In contrast 3 shows the course of the curve in the case of a drive with the converter actuation according to the invention.

The switching pressure curve is designated in both diagrams with "I", the torque curve with "II" and the curve of the input and output speed with "IH" and ¹¹ IV ".

The switching process begins at point "a", with the switching pressure becoming steep falls off. This drop can be seen in both graphs, through the Course of curve "I" in area "b". Only from about point "c" does a pressure build-up begin to about the original level, until the Slip phase "e" has ended for the newly engaged clutch. It is already evident here that the slip phase "e" is considerably shorter in the arrangement according to the invention.

In the case of the torque curve "II", the input torque is approximately the same in both cases. During the switching phase, it increases proportionally except for one high peak value in normal transmissions (Fig. 2). With the help of the converter, this is set during the slip phase for the powershift transmission occurring, torque peak cut off.

The shortening of the hatching phase and the simultaneous turning? torque reduction only result in significantly less friction work.

At the start of a switching process, the switching pressure always falls

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away. This drop is controlled by the hydraulic pressure transducer 14 and the relay 15 of the electromagnet 16, which sets the servomotor 18 in motion via the directional valve 17 to close the blades 4 of the converter so that only a small torque is transmitted to the powershift transmission. In the course of the switching process, the switching pressure rises, which has the effect that the converter is opened again via the devices 14 to 18 and thus a greater torque is transmitted.

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Claims (13)

Claim e: l \ Procedure for the operation of powershift transmissions that work with a converter, characterized in that at the start of a shift in the powershift transmission, e.g. for the purpose of a directional or Speed change, the torque to be absorbed by the gearbox is reduced by means of the converter and again after the shift has been carried out is increased. 2. The method according to claim 1, characterized in that the switching pressure is used in the powershift transmission as a manipulated variable to adjust the converter. 3. The method according to claim 1 and 2, characterized in that the Actuator can be controlled by means of the manual transmission actuation. 4. The method according to claim 1 to 3, characterized in that the Actuating converter actuation for the purpose of overriding steering and braking pressure and the normal work of the converter or the Vehicle is not disturbed. 5. The method according to claim 1 and 2, characterized in that the Changes in the input torque of the powershift transmission by means of the converter automatically depending on the transmission shift pressure he follows. 6. The method according to claim 1 to 5, characterized in that the change in the input torque of the powershift transmission by means of the converter is automatically controlled depending on the gear shift pressure via a timer relay. ORIGINAL INSPECTED 2701290 7. The method according to claim 1 to 6, characterized in that by the change in the gear shift pressure a servomotor for the torque converter is operated. 8. The method according to claim 1 to 7, characterized in that the Changes in the gear shift pressure via a solenoid valve, Hydraulic or pneumatic valve can be transferred to the converter. 9. Apparatus for performing the method according to claim 1, characterized in that between the power shift transmission and the converter a device for adjusting the converter, controlled by the switching pressure in the powershift transmission, is switched on. lU. Device according to claim 9, characterized in that in the Oil flow of the servomotor for the adjustment of the converter on the shift pressure in the powershift transmission is applied and actuated Control spool is switched on. 11. The device according to claim 9 and lü, characterized in that with the control unit (13) f * the powershift transmission a hydraulic one Pressure transmitter (14) is connected, which an electromagnet (16), a Controls hydraulic or pneumatic valve for the actuation of a directional control valve (17) connected to the Ulkreislauf of the servomotor (18). 12. The device according to claim 11, characterized in that the Directional valve (17) is spring-loaded on one side. 13. Apparatus according to claim 11 and 12, characterized in that An adjustable time relay 05) is switched on between the pressure transducer (14) and the electromagnet (16) to change the response time of the servomotor for the torque converter. 80Ö830 / 0Ö5?