DE3134171C2 - Switching device in a range group transmission - Google Patents

Abstract

In a range group transmission with a double-H gate for the manual shift lever, whose group switching takes place pneumatically, additional directional valves are installed between the existing directional control valves and the double-acting switching cylinder, which are controlled by the switching rail of the switching cylinder so that at the end of a group switching one of the The plunger of the additional directional control valve falls into a recess in the shift rail, this directional control valve switches over and the shift cylinder is thereby vented. This shortens the non-productive time when switching the area group and thus significantly reduces the possibility of incorrect switching.

Description

j * ren locked, but on venting of the belonging- switching time from one area group to the other

ί The 3/2-way valve (6) switched towards the end of the cylinder is shortened and this leads to incorrect switching

> ν is in series Group switching must be avoided.

f. 2. Switching device according to claim 1, characterized in that this task is achieved by the in the characterizing

| i indicates that the additional 3/2-way valves are part of the features listed in claim 1 solved

f; (10.18) a structural unit with the shift cylinder

; Form S (12). Advantages on that with little resources a shortening

$ 3. Switching device after one of the preceding switching times from one area group to another

ιI the claims, characterized in that it is achieved in the 35, through additional directional control valves,

I *. Switching rail (13) for switching the additional controls provided by a switching rail of a switching cylinder so cool 3/2-way valves (10, 18) notches (16, 19) that the switching cylinder is locked after

Ii: are, which at the same time the end divisions of the switch group switch-over is vented, with which the up to-

fk fix the rail (13). normal time-consuming venting that must be carried out before each

U 4. Switching device had to happen after one or more 40 switching of the switching cylinder,

f; of the preceding claims, thereby marked, is not applicable and incorrect switching is avoided. Of

*: indicates that of the lines (11, 20) further further, the switching time can be shortened by the fact that

I; Lines (25, 26) are branched off, the additional directional control valves to Sperrzy- a structural unit with the

t- alleviate (27,29) lead with piston (28,30), each switching cylinder form or their connecting lines

t according to the direction of movement of the shift rail (13), the 45 to the shift cylinder should be made as short as possible.

S one piston (30) or the other piston (28) of the shift rail contains notches that enable the switching Jf the compressed air against the hand lever (3) ge the additional directional control valves and also the fixation

i 'is pressed and locks it until the front of the shift rail is used. To switch the route

!; ■; area group switchover, shut-off valves, a groove can also be added in the switching rail.

! sen is. 50 should be brought, whereby at the end of the switching process each

5. Switching device according to claim 4, characterized in that the valve tappets are connected via one incline to another

;; indicates that only one locking cylinder (27 or 29) level is raised or lowered. Finally, throw with a piston (28 or 30) is provided, to which the lock cylinder, whose feed lines from the

'the two branched lines (25, 26) connected lines between the additional directional control valves and

are closed. 55 are branched off the switching cylinder and their respective

Piston only during group switching against

press the manual gearshift lever, incorrect switching is prevented with certainty. A further simplification is possible in that only one locking cylinder is provided The invention relates to a switching device 60 to which the two branched supply lines are connected.

are closed in a range group transmission according to the upper level.

handle of claim 1. The invention is based on an execution

The known mechanical gearbox with approximately example explained by means of drawings.

pneumatic area group switchover (DE-PS It shows

30 46 885), which has a double H-backdrop for the hand- 65 F i g. 1 schematically a control circuit of the invention

have shift levers are designed so that with the appropriate device with the lower operating

Passing through the neutral position with the manual shift range group;

lever of the shift cylinder, which controls the area group- F i g. 2 the control circuit according to FIG. 1 with a lock

device when the upper range group is switched;

3 shows a diagram of the pressure curve in a Shift cylinder and

F i g.4 a double H shift pattern, based on the Diagram in Fig. 3.

The in F i g. 1 schematically illustrated switching device has a switching shaft 1 with a groove 2. the Shift shaft 1 can be rotated about its longitudinal axis, is axially displaceable and has a manual shift lever 3 tied together. When switching from 4th to 5th gear, the manual lever! 3 the selector shaft 1 in Moved in the direction of an arrow 4, a plunger 5 of a directional valve 6 falling into the groove 2 and the directional valve 6, which is in the first group (1st to 4th gear) of the range group transmission in the locked position switches to passage In this position, the pressure medium comes from a pressure source 7 via lines 8, 9, the directional control valve 6, a directional control valve 10 and a line

11 to a shift cylinder 12. As a result, w ^; -d a switching rail 13 switching the range group controlled in the direction of an arrow 14 At the end of this movement, a plunger 15 of the directional valve 10 engages in a notch 16 of the switching rail 13, thus bringing the directional valve 10 into another switching position and causes the switching cylinder 12 is vented via the line 11 at the directional control valve 10. After the above-described processes have been completed, the range group transmission is switched from the first to the second group (5th to 8th gear). As a result of the shifting of the shift rail 13 in the direction of arrow 14, a tappet has become

17 of a directional valve 18 from a notch 19 in the shift rail 13 lifted, with which the directional control valve 18 was opened and the air from the counter space of the switching cylinder 12 via a line 20, the directional valve 18, a line 21 and a directional valve 22, the plunger 23 thereof pressed by the control shaft 1 and thus the directional control valve 22 has been switched to venting, escape can. Because the counter space of the shift cylinder

12 is not under pressure after a switchover, works the switching process ahead of you faster. By measurement, simplified in FIG. 3 shows a reduction in switching time determined in the switching device according to the invention compared to the known of about 0.08 seconds This saving of time in the group switchover, which is generally small, has the risk of incorrect switching in practice substantially reduced.

When shifting down from the second to the first group of the transmission (in the exemplary embodiment from V. into the fourth gear) is the actuation of the manual lever 3, the selector shaft 1 in the direction of an arrow

32 moves, with which the tappets 23, 17 of the directional control valves 22,

18 and thus the compressed air from the pressure source 7 via the lines 24, 21 and 20 to the scraping cylinder 12 arrives and the shift rail in the direction of an arrow

33 moves until the plunger 17 of the directional control valve 18 engages in the notch 19. This is the switching process ends and the switching cylinder 12 is vented via the directional control valve 18.

Based on the F i g. 2, a locking device is explained below. Lines 25, 26 lead to locking cylinders 27,29, which work with spring return stroke. When shifting up from the first to the second group Compressed air, as described in more detail above, via line 11 to the shift cylinder 12. This until the end of the The compressed air available for group switching is supplied via line 25, which is connected to line 11 in Connection is fed to a locking cylinder 27, the piston 28 of which is in the position shown in dashed lines shifts and thus locks the manual shift lever 3, which can be rotated about an axis 31, and only after this has taken place Group switching by means of a return spring brings it back to its starting position and thus the manual shift lever 3 releases again When switching back from the second to the first group, the locking process runs in in a corresponding manner via the line 26, the locking cylinder 29 with its piston 30.

Another embodiment provides only one locking cylinder with a spring return stroke 27, 29. Both are there Pressure lines 25,26 to one of the locking cylinders 27,29 connected.

In the diagram (FIG. 3) the air pressure ρ is plotted on the ordinate and the time t is plotted on the abscissa. The curve shown in dashed lines shows the shift pressure profile in known devices according to the preamble, while the curve shown continuously shows the profile according to the invention. The non-productive time is shown with the designation t “

F i g. 4 illustrates the area, based on the diagram in FIG. 3, in which the inventive Switching device is effective.

For this purpose 2 sheets of drawings

Claims (1)

1 2 § Position causes, constantly pressurized with compressed air I claims: Before changing the range group, the ρ shift bar in the shift cylinder can be set in motion! *! .Switching device in a range group, a time must 5 Nebeiizeit t _n shown is to be waited until sieve -g ble and axially displaceable selector shaft, with the pressure increase on the switched side with the II two 3/2-way valves that overlap with one at the switching pressure drop on the ventilated side I shaft attached locking groove to control a after this non-productive time the switch moves t- |; Compressed air flow to an alternating pressure rail and switches the area group. With these i | openable shift cylinder work together, io gears it often happens that when switching from ■ | with an IV connected to the cylinder ends to V gear or vice versa the manual shift lever || Line is switched so quickly via one in each line that the changeover % \ tes 3/2-way valve either with a pressure source circuit is done, but the switch rail of the switch t- $ can be connected or vented, so that the cylinder could not be switched further because of II indicates that in the two lines (9, 15 of the auxiliary time t " explained above. This leaves I 11; 21, 20) each with an additional 3/2-way valve range group transmission in the first group (!. To IV. If ( 10.18) is provided by a gear with the piston). The 5th gear fs of the shift cylinder (12), which was engaged by the incorrect shift, corresponds to the 1st gear of the first group. This leads % (13) then alternately on blocking or passage to damage the engine. In order to avoid this danger, the position can be controlled when a group is walking around, until now a visual display in the ar- % circuit has ended, with the disabled graduation board being provided on the one hand, which indicates which area; * ■ additional, but on venting of the associated group is switched on. Despite before i: ·; Cylinder end switched 3/2-way valve (18) with the device mentioned, a faulty switching, as above loading ) / ■ carry out the one 3/2-way valve that is switched on. fe til (22) and, on the other hand, the geared to passage 25 The object of the invention is to provide a switching device ■ ;; tete additional 3/2-way valve (10) with dsm other of the type mentioned so that the