Switch actuatable operating system for folding top hydraulic drive elements

An operating system for hydraulic drive elements of a folding top, such as a lowerable folding top of a convertible, can be actuated by switching apparatus. The drive elements are fed by a pressure source from a pressure medium reservoir via an inlet and connected to a return to the pressure medium reservoir. Switchable directional control valves distribute the pressure generated by the pressure source to the drive elements moving various parts. Actuation of the directional control valves corresponds to a given sequence of movements of the top. To simplify the operating system, a plurality of operational elements assigned to various operating functions can be switched at the same time by individual directional control valves. As a result, a smaller number of expensive directional control valves is required.

BACKGROUND AND SUMMARY OF THE INVENTION 
The present invention relates to an operating system for hydraulic drive 
elements of a folding top, in particular of a lowerable folding top of a 
convertible, which can be actuated by switching apparatus, and, more 
particularly, to an operating system having drive elements feedable by a 
pressure source from a pressure medium reservoir via an inlet and 
connectable to a return to the pressure medium reservoir, switchable 
directional control valves for distributing pressure generated by the 
pressure source to the drive elements for moving various parts of the 
convertible folding top system and having an actuation of the directional 
control valves corresponding to a given sequence of movements thereof, 
limit switches for actuating the directional control valves, the limit 
switches being positively operated by driven parts, and a plurality of 
driven parts in the form of closures which can be locked and unlocked by 
double-acting working cylinders and mechanically arrested in a release 
position thereof against locking by an associated working cylinder. 
An electrohydraulic operating system is described in DE 38 26 789 Al. 
Although the known operating system has a high functional reliability, it 
is also technically relatively costly. One factor in particular driving up 
the costs is that a relatively large number of expensive directional 
control valves are required in the system. 
An object of the present invention is to improve operating systems such 
that a less costly operating system is possible without sacrificing 
functional reliability. 
The foregoing object has been achieved according to the present invention 
by providing that the pressure source has a feed line arranged to be 
constantly flow-connected via inlet lines to a rod side of the working 
cylinders interacting with the closures, as a result of which a 
pressurization of the pressure medium in the feed line results in an 
impingement of the working cylinders in a locking advancement direction 
thereof, and the working cylinders are configured to be differentially 
actuatable by assigned ones of the directional control valves, by 
activation of which a drive element of another driven part is switchable 
along therewith.

DETAILED DESCRIPTION OF THE DRAWINGS 
The sequence of movements of the folding top 1 illustrated in FIG. 1 is 
described in brief below in (a)-(j) by key words and refers to views 
(a)-(j) of FIG. 1, respectively: 
(a) a folding top designated generally by numeral 1 is closed, hydraulic 
system is pressureless, all the closures are locked; 
(b) a fabric-holding hoop on the rear folding-top part 2 is unlocked; 
(c) the fabric-holding hoop on the rear folding-top part 2 is swivelled-up; 
(d) a folding-top compartment lid 3 is unlocked; 
(e) the folding-top compartment lid 3 is swung-up to expose an opening of a 
folding-top compartment 4; 
(f) front closures on the frame above the windscreen are unlocked; 
(g) the folding top 1 is opened and laid down with the rear folding-top 
part 2, folded one over the other, in the folding-top compartment 4; 
(h) the folding-top compartment lid 3 is swung-down; 
(i) the folding-top compartment lid 3 is locked; and 
(j) the folding top 1 is completely open, and the hydraulic system is 
pressureless again. 
During closing of the folding top 1, these movements occur in the reverse 
sequence from that described above. 
The operating sequence of the folding top 1, of the rear folding-top part 
2, of the folding-top compartment lid 3 and of the respectively assigned 
closures is controlled by a known type of central electronic control 
device which receives its input signals, determining the position at any 
one moment of the parts to be driven, essentially by the positive 
operating of limit switches. Depending on the directional preselection at 
an operating switch, configured as a shift key, for opening and closing 
the top 1, the valve operating functions required for a coordinated 
sequence of movements of the parts to be driven are actuated in the 
hydraulic system shown in FIG. 2 by output signals of the control device. 
For reasons of overall clarity, representation of the electrical control 
lines has been dispensed with in the drawing. 
The line system is supplied centrally from a hydraulic unit designated 
generally by the numeral 5 and comprises a pump 5.2, to be driven by an 
electric motor 5.1, a pressure-medium sump 5.3 with venting, a 
pressure-control valve 6 and also a plurality of pressure-medium filters 
7. In addition, a plurality of test connections 8 are arranged on the 
hydraulic unit 5. Other pressure-control valves 6, pressure-medium filters 
7 and test connections 8 are additionally located at all relevant points 
of the line network, as marked by the drawn-in symbols in FIG. 2. The 
pressure medium delivered by the hydraulic unit 5 is fed through a feed 
line 9 initially into a right-hand valve block 10 of the system. This 
feeding takes place directly, i.e., as distinct from the known system, 
without interconnection of a directional valve, as soon as the pump 5.2 
has built up an adequate delivery pressure. The feed line 9 in the valve 
block 10 is flow-connected by an overflow line 11 to a corresponding feed 
line in a left-hand valve block 12. 
The feed line 9 in the left-hand valve block 12 supplies four 
electromagnetically switchable 2/3-way valves 13, 14, 15 and 16 with the 
pressure medium. The feed line 9 in the right-hand valve block 10 is used 
for directly supplying two and indirectly supplying three identical 
directional control valves 17, 18 and 19. Only the directional control 
valve 17 serves to operate the folding top. By contrast, the directional 
control valves 18, 19 operate a rollover bar which can be moved by 
swivelling between a lowered rest position and an erected protecting 
position. 
Furthermore, the feed line 9 is flow-connected directly, i.e. without 
interconnection of a directional control valve, via inlet lines 20, 21, 
22, 23 and 24 to the rod side of assigned hydraulic cylinders 25, 26 and 
27, respectively, which are in each case arranged in pairs. 
The two hydraulic cylinders 25 drive front folding-top closures of the top 
1 direction-reversibly between the locking position and the unlocking 
position, by which the roof cap can be locked above the windscreen. The 
two hydraulic cylinders 26 are used to drive two middle closures, by which 
the folding-top compartment lid 3 can be locked to the vehicle body. 
Finally, the two hydraulic cylinders 27 effect the rotary drive output of 
two rear folding-top closures, by which the fabric-holding hood of the 
rear folding-top part 2 can be locked on the closed folding-top 
compartment lid 3. 
All the pivoted-latch closures driven by the hydraulic cylinders 25, 26 and 
27 have a known design as described in DE 37 08 095 C2, and therefore need 
not be described further so as not to obscure the essential features of 
the present invention such as the pivoted-latch closures which are held in 
their release position and lockable by the assigned working cylinder only 
after the forked pivoted latch has been turned through an unlocking 
rotation angle by the entering closure pin. 
Furthermore, there are two hydraulic cylinders 28 for the swivelling drive 
of the folding-top compartment lid 3. The inlet of these cylinders 28 is 
respectively controlled on the rod side by the directional control valve 
15 and on the solid piston side by the directional control valve The inlet 
lines to two hydraulic cylinders 29, which are connected by their rod 
side, are enabled by the directional control valve 15, whereas the inlet 
lines to the solid piston side of the hydraulic cylinders 26 are enabled 
by the directional control valve 16. The hydraulic cylinders 29 serve for 
the swivelling drive of the fabric-holding hoop belonging to the rear 
folding-top part 2. 
Two hydraulic cylinders 30 are provided for the main swivelling drive of 
the top 1 and are articulated on the lateral pillars of the top 1. These 
cylinders 30 are actuated on their solid piston side by the directional 
control valve 13, with the inlet to the solid piston side of the hydraulic 
cylinders 27 being enabled. Finally, the inlets to the piston rod sides of 
the hydraulic cylinders 30 and to the solid piston sides of the hydraulic 
cylinders 25 are enabled by the directional control valve 17. 
During opening of the top, the following sequence is obtained on account of 
the simplified system: 
(i) By switch actuation, the pump 5.2 of the hydraulic unit 5 becomes 
operational and builds up the working pressure. As a result, the rod sides 
of the cylinders 25, 26 and 27 are pressurized. This pressure increase 
does not have any further effect, since the assigned closures remain in 
their locked end position and are only pressed slightly further in the 
locking direction. Directional control valve 13 is activated so that the 
solid piston sides of the cylinders 30 are pressed in the pushing-out 
direction of the piston (synonymous with the folding top closed position). 
In parallel with the foregoing operation, the rear folding-top closures 
are unlocked by the differential impingement of the cylinders 27 (FIG. 1b) 
(ii) In addition, directional control valve 15 is switched. Consequently, 
the pressure medium acts on the rod side of the cylinders 29, resulting in 
the pistons being pushed in to swing up the fabric-holding hoop (FIG. 1c). 
At the same time, the rod side of the cylinders 28 is pressurized, 
resulting in the closed lid being pressed in the closed direction. 
(iii) Directional control valve 16 is also cut in. As a result, the supply 
lines to the solid piston side of the cylinders 26 are enabled, as a 
result of which their pistons are differentially pushed out and the middle 
closures are opened (FIG. 1d). At the same time, the inlet lines to the 
solid piston side of the cylinders 28 are opened, as a result of which the 
pistons of the cylinders 28 are differentially pushed out and thereby 
swing up the folding-top compartment lid 3 (FIG. 1e). 
(iv) Then, directional control valve 17 is also switched off. As a result, 
the pressure medium column on the solid piston side of the cylinders 25 
then becomes effective which causes the differential advancement of the 
pistons. The front folding-top closures are thereby unlocked (FIG. 1f). At 
the same time, the inlet lines to the piston rod side of the cylinders 30 
are enabled, so that the actuation of the top 1 in the closed direction is 
differentially maintained. This results in an easy-action unlocking of the 
tension-relieved front closures. 
(v) Directional control valve 13 is closed. As a result, the pistons of the 
cylinders 30 are retracted, and the top 1 is swung back into the 
folding-top compartment 4 (FIG. 1g). 
(vi) Directional control valve 16 is then closed. As a result, the 
cylinders 26 of the middle closures are impinged in the pushing-in 
direction of the pistons, i.e. in the locking direction. Because of the 
mechanical arrest of the closures, however, the closures remain blocked. 
At the same time, the pressure medium column on the solid piston side of 
the cylinders 28 is enabled, so that the pistons are pushed in and swing 
the lid 3 closed (FIG. 1h). If the pivoted latch of the middle closures is 
released by the striking closure pins, the piston impingement on the rod 
side of the cylinders 26 becomes effective and locks the folding-top 
compartment lid 3 (FIG. 1i) by the middle closures. 
(vii) Thereafter, all the directional control valves 13, 14, 15, 16 and 17 
are switched off and the hydraulic unit 5 is disconnected, because the top 
1 is open (FIG. 1j). 
During closing of the opened top 1, the following sequence of movements is 
obtained: 
(i) By operating switches in the closing direction, the hydraulic unit 5 is 
switched on and builds up the required working pressure. By switching on 
the directional control valve 16, the cylinders 26 are differentially 
impinged, as a result of which the middle closures are unlocked. At the 
same time, the cylinders 28 are pressurized on the solid piston side and 
swing the folding-top compartment lid 3 up into its open position. 
(ii) Directional control valves 13 and 15 are cut in. The top 1 is 
increasingly closed by impingement of the cylinders 30. The closures which 
can be operated by the cylinders 27 are differentially impinged in the 
unlocking direction. On the rod side of the cylinders 29, the pressure 
medium pressure acts and holds the fabric-holding hoop in its raised 
position. At the same time, the supply line to the rod side of the 
cylinders 28 for the lid 3 is released. The directional control valve 17 
is cut in time-dependently by the control electronics which allow the use 
of one less limit switch. This cutting-in must take place before the 
closure pins of the top 1 interact with the front closures, because the 
inlet lines to the rod side of the working cylinders 30 are enabled by 
directional control valve 17 and consequently effect differential working 
thereof. This ensures that the top 1 does not hit the roof frame too hard. 
In addition, the inlet lines to the solid piston sides of the cylinders 25 
are enabled by directional control valve 17, as a result of which the 
differentially extended pistons unlock their assigned closure. With the 
striking of the closure pins against the front folding-top closures, 
directional control valve 17 is switched off. Consequently, the cylinders 
25 are pushed out, impinged by the pressure medium column of the inlet 
line 20, and effect a locking of the front closures. 
(ii) Then, directional control valve 16 is switched off. As a result, the 
cylinders 28 are pushed in and swing the lid 3 closed. At the same time, 
the pressurization of the solid piston side of the cylinders 26 is 
discontinued, as a result of which the pistons of the latter are pushed 
in, after lifting the mechanical blocking, by the pressure medium columns 
of the inlet lines 21, 22, respectively, and a locking of the middle 
closures is thereby brought about. 
(iv) Directional control valve 14 is opened, and directional control valve 
15 is closed. As a result, the cylinders 29 are impinged in a pushing-out 
manner and swing the fabric-holding hoop down into its resting position. 
At the same time, the top 1 is actuated further in the closing direction 
and the cylinders 27 in the unlocking direction of their closures. 
(v) On reaching the limit switch signalling the unlocked end position of 
the fabric-holding hoop, directional control valve 13 is also switched 
off. As a result, the pistons of the cylinders 27, impinged with pressure 
medium via the supply lines 23 and 24, retract and thereby turn the 
closures of the fabric-holding hoop into the closed end position. 
(vi) Finally, the hydraulic unit 5 is disconnected and all the directional 
control valves are enabled, after which the top 1 is closed. 
The operating system which has been thus greatly simplified according to 
the present invention allows altogether four less directional control 
valves to be used, by various operating functions being actuated in 
parallel as above described. The return lines, not mentioned so far, from 
the two valve blocks 10, 12 to the hydraulic unit 5 are indicated by short 
dashed lines. 
On account of the space saving achieved by requiring with less valves, it 
is now readily possible for the first time also to integrate the two 
directional control valves 18, 19 for a rollover bar of known construction 
into the right-hand valve block 10 and feed valves 18, 19 through the 
joint feed line 9. As a result, the line network as a whole can now be 
made more compact. This rollover bar is spring-loaded in the erecting 
direction and can be moved for curved operation by a hydraulic cylinder 
31. The operation of the rollover bar aimed for by actuating the 
directional control valve 19 is possible by looping into the circuit of 
the directional control valve 18 only if the latter is likewise enabled, 
as a result of which two hydraulic cylinders 32 unlock, against a spring 
loading, an arresting mechanism which unsecures the rollover bar. 
Although the invention has been described and illustrated in detail, it is 
to be clearly understood that the same is by way of illustration and 
example, and is not to be taken by way of limitation. The spirit and scope 
of the present invention are to be limited only by the terms of the 
appended claims.