DE2263358C2 - Hand-controlled servo actuation system for multi-stage working pressure modulation for shifting the gears of motor vehicle change-speed transmissions - Google Patents

Description

The invention relates to a hand-operated servo actuation system according to the preamble of the patent claim.

The subject of the unpublished DE-Patent 21 41 693 is such a servo actuation system, wherein a greater force is used for engaging the first gear than for engaging the second or higher gears. As the gears move up, the force required is gradually reduced. To downshift the gears t ; s from a higher to a lower gear, on the other hand, a step-wise, comparatively greater force has to be used than is necessary for a corresponding upshift in the same gear step

Such servo actuation systems are very simple under construction and workers, also very reliable. However, the time for engaging the gears is relatively long and thus very disadvantageous.

It is therefore the object of the invention to provide a servo actuation system according to the preamble of claim 1 To be improved so that the engagement of the gears takes place faster and thus shorter shift times result.

This task is fulfilled with the characterizing features of the patent claim

While according to DE patent 21 41 693 the working pressure for the actuating cylinder, starting from a relatively low pressure, can be built up by the pump must, the invention is based on a relatively high pressure and generated exclusively by pressure reduction the working pressure for a double-acting actuator cylinder.

Instead of the usual build-up of pressure a gradual pressure reduction is generated

This reverse procedure resulted in an unforeseeable increase in the switching speed. While in each of the prior art a total of 2 seconds were required to build up the pressure and thus for the switching, only 0.05 seconds are now required.
From DE-OS 19 49 572 devices are with

a pressure control valve known, which depends on the gate position and switching direction can be modulated Pressing the gears, but controls the closing time of a main clutch as a function of

the inflow.

Further details of the invention are explained using exemplary embodiments and drawings
F i g. 1 a circuit diagram with a mechanically operated pressure control valve,

2 shows a circuit diagram according to FIG. 1, but with

an electro-hydraulically operated pressure control valve.

The following description applies to both figures,

so 1 and 2, readable. The same parts are given the same reference symbols Mistake.

The F i g. 1 and 2 show a pressure line 27 which is fed by a pump 29 and has a constant pressure. A line 25 with a pressure control valve 23 is connected to the pressure line 27 Depending on the positions EFG in the alley of the gear switch actuated. On the pressure control valve 23 there is also a pressure-controlled actuator 22, which is connected to the line 25 via a 3/2-way valve and line 11 Line section 26 are parallel 3/2-way valves 14, 14a, whose, for example, mechanical (FIG. 1) actuations 13, 13a are actuated depending on the gear engaged. The line section 26 goes via the 3/2-way valve 14 to a further pressure control valve (1). The control pressure for the servo control is routed from the branch 40 or 41 to the actuator cylinder 30

The mode of operation of the new circuit is such that a pressure modulation is achieved in which the Pressure control valve 23 results in a modulation depending on the position of the gearshift in the alley, which in addition through the valve 9 depending on the switching direction - that is, depending on whether it is switched up or down is - is modulated. The modulated pressure produced in the line 26 is applied to the further Pressure control valve 1, when valve 14 is switched, again gradually reduced when valve 14a is switched the pressure modulated by valve 23 remains.

For this purpose 2 sheets of drawings

Claims (1)

Claim: Hand-controlled servo-actuation system for a multi-stage working pressure modulation for shifting the gears of motor vehicle change-speed transmissions with interruption of traction, with an actuating cylinder to which a pressure is applied depending on the gear, gate and shifting direction, the pressure being via a pressure control valve depending on the gears being switched and is controlled via a first 3/2-way valve depending on the switching direction, characterized in that the system pressure (line 25) supplied by the pump (29) is controlled via the pressure control valve (23) by two parallel second (14) and third (14a) 3/2-way valves optionally depending on the gangs; e (H or J) a double-acting Stellzynndei {-ΐ *?) is fed, the pressure through a second 3/2-way valve (14); , I switched pressure control valve (1) is reduced in a fixed ratio.