GB2266930A

GB2266930A - Controlling hydraulic actuators

Info

Publication number: GB2266930A
Application number: GB9223737A
Authority: GB
Inventors: Wolfgang Kladiwa; Gerhard Huber; Klaus Stolle
Original assignee: Hoerbiger Ventilwerke GmbH and Co KG
Current assignee: Hoerbiger Ventilwerke GmbH and Co KG
Priority date: 1992-05-15
Filing date: 1992-11-12
Publication date: 1993-11-17
Anticipated expiration: 2012-11-12
Also published as: JPH05330344A; SE9301648D0; ITMI922447A0; FR2691211B1; DE4236517C2; DE4236517A1; GB9223737D0; SE9301648L; ES2070745R; FI932210A; SE507581C2; IT1255913B; AT396613B; FR2691211A1; FI932210A0; NL9300624A; ES2070745B1; GB2266930B; ATA100992A; ES2070745A2

Abstract

A hydraulic circuit for operating a vehicle cover (soft top) includes a non-return valve (23) which prevents fluid leaking from a cylinder space (6) and this locks the raised cover in position even over a long period. To lower the cover the valve (23) has its closing action cancelled eg by a pilot line (24) or is bypassed (Fig. 2) to allow the fluid to leave the cylinder. <IMAGE>

Description

2266930 1 Hydraulic arrangement for a vehicle cover The invention relates

to an hydraulic actuating arrangement for a vehicle cover, having at least one cylinder/piston arrangement, which engages on the cover and the operating spaces of which are connected to a reversible pump by way of hydraulic lines.

Actuating arrangements of the type described are known and allow even considerable forces to be exerted in a simple manner on a relatively small space by making use of the known advantages of hydraulic operating cylinders, which is advantageous particularly in the case of the abovementioned use for a vehicle cover as a result of the conditions of space which are generally very restricted for the actuation of the cover. Very simple conditions for controlling the actuating arrangement are permitted by the reversing valve generally provided and the pump which is reversible in its conveying direction, it only being necessary to house a pump carrier - comprising the pump, the reversing valve and where appropriate pressure-relief valves, emergency actuating arrangements and the like and the connecting hydraulic lines, apart from the operating cylinder or cylinders engaging directly or indirectly on the cover.

2 In the case of the previously known actuating arrangements, problems have repeatedly arisen on account of the travelling wind acting upon the opened, more or less folded cover, particularly in the case of the cover arrangements which at present are used increasingly frequently and in which a covered accommodation of the opened cover in a corresponding receiving space in the vehicle is dispensed with on grounds of space. As a result of guiding the travelling wind over the open' interior of the vehicle, it may happen that the opened cover is subjected to a force acting in the closure direction and leading to a partial closure of the cover, and this can give rise to grave problems at least at higher speeds of the vehicle.

Apart from the possibility of holding the cover in the opened state by mechanical means, for example by means of snap closure fastenings, hooks and eyelets and the like, which naturally detracts from the ease of use, the previous practice has been to rely essentially only on the hydraulic obstruction of the cylinder/piston arrangements when the cover is opened, this obstruction occurring when there is no delivery from the pump, since the reversing valve itself separates the two sides. In this case, however, the rod side and the piston side of the cylinder/piston arrangement(s) used still remain 3 connected or opened by the inevitable leakage in the pump and in the reversing valve, so that the respective cover can still partially close in a disadvantageous manner particularly when the forces described have been effective for a long time.

Apart from the above-mentioned mechanical methods of holding down the cover itself, under certain circumstances there is an obvious solution which lies in the use of so-called lockable cylinders, in which the piston or the piston rod can be secured mechanically in at least one defined position with respect to the cylinder, but this entails a generally increased structural outlay and also makes the control and operation of the actuating arrangement more complicated and therefore prone to breakdown.

The object of the present invention is to improve an hydraulic actuating arrangement of the type described above in such a way that the described disadvantages of the known or obvious arrangements are avoided, and that in particular it is possible to ensure in as simple as possible a manner that the opened cover cannot be partially closed inadvertently by the travelling wind or other forces acting in this way.

In the case of an hydraulic actuating arrangement 4 of the type described above, this object is attained according to the invention in that a non-return valve, the recoil action of which is stopped as the cover is closed hydraulically, is arranged in the hydraulic line to the operating space which opens the cover. In this way, the cylinder of the cylinder/piston arrangement(s) engaging on the cover, or at least one of them, is held under pressure by way of the non-return valve as the pump being run to open the cover is stopped, it being practically impossible for leakages of the type described above to occur and a secure hydraulic locking of the opened cover position being ensured. In order to close the cover hydraulically in the normal manner, the recoil action of the non-return valve is stopped in a suitable manner described below in two advantageous variants, so as to ensure that the hydraulic medium flows off from the respective cylinder space practically without obstruction. When opening the cover hydraulically in the normal manner, the non-return valve is in any case traversed in the direction not shut off, so that the hitherto otherwise customary actuation is not essentially affected as a whole. With respect to the structural size of the entire actuating arrangement and the controllable holding forces the non-return valve is preferable to the other possibilities mentioned above for locking the opened cover, since for example mechanical locking of the piston rods requires greater structural space as the holding forces increase, whereas the fitting space for the non-return valve according to the invention does not vary.

In the case of an actuating arrangement of the type described, having at least two parallel cylinder/piston arrangements, in a further preferred embodiment of the invention a common non-return valve is arranged upstream of the branch of the hydraulic lines to the individual cylinder/piston arrangements, thus producing a very inexpensive and space- saving arrangement.

In accordance with another further development of the invention the nonreturn valve can be constructed so as to be hydraulically shiftable and can be connected by way of a control line to the hydraulic line leading to the operating space which closes the cover. In this way any additional step for shifting or releasing the non-return valve for closing the cover hydraulically in the normal manner becomes absolutely superfluous, since in this case the pressure applied by the pump for this purpose now also effects at the same time the release of the non-return valve.

In accordance with another advantageous further development of the invention, however, it can also be provided that a pressure-relief valve, which bridges the 6 non-return valve when the cover is closed hydraulically from a preferably adjustable pressure threshold, is provided parallel to the non-return valve. In this way, it is unnecessary to provide a special control line for shifting or releasing the non-return valve - as soon as the hydraulic pressure operative during the normal closure of the cover exceeds a specific magnitude pre-set by the pressure-relief valve, the necessary by- pass flow of the hydraulic medium can take place relatively unobstructed by avoiding the blocked non-return valve. In addition, turning on a pressure-relief valve of this type provides the advantage that increases in pressure in the system, such as can occur for example in the case of a vehicle standing in the blazing sun, can be disregarded - as soon as the release pressure provided by the pressure-relief valve is exceeded, hydraulic medium is discharged into the reservoir.

In the case of an actuating arrangement with a pump carrier comprising the pump and a reversing valve, in a further embodiment of the invention the non-return valve and where appropriate the pressure-relief valve is or are integrated in or on the pump carrier, thus resulting in simple, inexpensive and space-saving arrangements which even with respect to maintenance and assembly do not require any increased assembly costs as compared 7 with the previous solutions.

The invention is explained in greater detail below with reference to the embodiments illustrated diagrammatically in the drawings, in which Fig. 1 shows an embodiment of an hydraulic actuating arrangement for a cover (not shown further) fitted in a vehicle, and Fig. 2 shows another embodiment according to the invention.

The hydraulic actuating arrangement illustrated in Fig. 1 is used for opening and closing a cover (not shown further) fitted in a vehicle. Two cylinder/piston arrangements 1, 2 are provided which engage on the cover or on suitable displacement elements or the like of the cover and the pistons 3 of which are displaceable by means of hydraulic medium in cylinders 4, the actual actuation of the cover being performed by way of the piston rods 5 or elements (not shown further) connected thereto.

The operating spaces 6, 7 of the cylinder/piston arrangements 1, 2 are connected by way of hydraulic lines 8, 9 to a reversible pump 10 which in turn is 8 drivable by an electric motor 11.

The operating spaces 6, which can be acted upon with operating pressure when the cylinder/piston arrangements 1, 2 are retracted, are connected by way of the hydraulic lines 8 to a point 12, from which the hydraulic lines 8 for the two cylinder/piston arrangements 1, 2 are jointly guided by way of a pump connexion 13 to a reversing valve 14 which is connected by way of a suction line 15 to a reservoir 16 for hydraulic medium. The operating spaces 7 acted upon with pressure when the cylinder/piston arrangements 1, 2 are extended are connected by way of the hydraulic lines 9 to a point 17 - the hydraulic lines 9 likewise jointly guided from there extend in turn by way of a pump connexion 18 to the other side of the reversing valve 14. In the area between the reversing valve 14 and the pump connexion 13 and 18 respectively, both the hydraulic line 8 and the hydraulic line 9 are connected to a discharge line 19 which leads to the reservoir 16 and into which pressure-relief valves 20 are fitted in each case.

A by-pass line 21, in which an emergency valve 22 is inserted, additionally branches off from the connexion point 12 of the hydraulic lines 8 to the reservoir 16, the emergency valve 22 permitting 9 emergency actuation by hand for closing the cover for example in the event of failure of the supply voltage for the motor 11.

A shiftable non-return valve 23 is arranged in the hydraulic line 8 to the operating spaces 6 which open the cover by the cylinder/piston arrangements 1, 2 being retracted, the non-return valve 23 being connected by way of a control line 24 at the connexion point 17 to the hydraulic line 9 connected to the other operating spaces 7, so that with an operating pressure active in the hydraulic line 9 the recoil action of the non-return valve 23 is stopped and the said non-return valve 23 can be traversed even in the direction otherwise shut off.

During the normal hydraulic opening of the cover by the retraction of the pistons 3 into the position illustrated, hydraulic medium is supplied under pressure to the operating spaces 6 on the rod side by suitably changing over the pump 10 and the reversing valve 14 by way of the hydraulic line 8 and the non-return valve 23, which although it acts as a recoil (on account of the lack of pressure by way of the control line 24) is traversed in the open direction, the hydraulic medium forced out of the operating spaces 7 on the piston side arriving at the suction side of the pump 10 by way of the hydraulic line 9 or - if superfluous - being discharged by way of the by-pass 19. With the pump 10 turned off in the opened position of the cover (or the pistons 3 retracted), it is impossible for the pistons 3 to be extended and therefore for the cover to be partially closed for example as a result of the action of the travelling wind, since the operating spaces 6 on the rod side are closed hydraulically by way of the non-return valve 23.

During the normal hydraulic closure of the cover by extension of the pistons 3, the operating pressure acts by way of the hydraulic lines 9 on the one hand in the operating spaces 7 on the piston side and on the other hand by way of the control line 24 on the thereby released non- return valve 23. In this way the hydraulic medium forced out of the operating spaces 6 on the rod side can be supplied by way of the hydraulic line 8 to the suction side of the pump 10 which draws the hydraulic medium additionally required out of the reservoir 16 by way of the reversing valve 14.

A pump carrier - which receives the pump 10 together with the motor 11, the reversing valve 14, the two pressure-relief valves 20, the emergency valve 22, the non-return valve 23 and the reservoir 16 - is indicated in dash-dot lines and is designated 25, so that the entire actuating arrangement essentially 11 comprises only the said pump carrier 25, the two cylinder/piston arrangements 1, 2 and the hydraulic lines 8, 9 and is therefore easy to assemble or fix in the vehicle.

In the illustration of a further embodiment according to the invention as shown in Fig. 2, the same parts or parts similar in their operation have also been provided with the same reference numerals - in order to avoid repetition, therefore, concerning these components and the corresponding description of their operation, reference is made to the above remarks in connexion with Fig. 1.

In the embodiment according to Fig. 2, the only essential change with respect to Fig. 1 is that the non-return valve 23 is not made releasable or shiftable, so that a separate control line (starting from point 17 or the hydraulic line 9 in accordance with Fig. 1) is not required. In order to allow the recoil action of the non-return valve 23 to be stopped during normal hydraulic closure of the cover, in this case a pressure- relief valve 26 is provided parallel to the non-return valve 23, the pressure-relief valve 26 bridging the non-return valve 23 during the procedure of normal hydraulic closure of the cover from a preferably adjustable pressure threshold. This pressure threshold 12 is generally set so high that it is exceeded only by the operating pressure of the system which is effective when the pump 10 is running, but apart from that the pressure threshold could if necessary be set lower so that under certain circumstances even the emergency valve 22 would become superfluous, since with manual closure of the cover (in the event of failure of the operating pressure) it would only be necessary to overcome this threshold, which, in order to ensure the operation intended in the scope of the invention, must naturally lie above a pressure threshold which permits a partial closure of the cover by the travelling wind.

Apart from the illustrated embodiments with a common non-return valve for the operating spaces which open the cover., it would naturally also be possible for individual non-return valves to be provided separately for each cylinder/piston arrangement and if necessary also for two operating spaces in each case, which however would again increase the structural outlay.

13 Cl ai ms:

1. An hydraulic actuating arrangement for a vehicle cover, having at least one cylinder/piston arrangement, which engages on the cover and the operating spaces of which are connected to a reversible pump by way of hydraulic lines, characterized in that a non-return valve (23), the recoil action of which is stopped as the cover is closed hydraulically, is arranged in the hydraulic line (8) to the operating space (6) which opens the cover.

Claims

2. An actuating arrangement according to Claim 1, having at least two

parallel cylinder/piston arrangements, characterized in that a common nonreturn valve (23) is arranged upstream of the branch (12) of the hydraulic lines (8) to the individual cylinder/piston arrangements (1, 2).

3. An actuating arrangement according to Claim 1 or 2, characterized in that the non-return valve (23) is constructed so as to be hydraulically shiftable and is connected by way of a control line (24) to the hydraulic line (9) leading to the operating space (7) which closes the cover.

14 4. An actuating arrangement according to Claim 1 or 2, characterized in that a pressure-relief valve (26), which bridges the non-return valve (23) when the cover is closed hydraulically from a preferably adjustable pressure threshold, is provided parallel to the non-return valve (23).

5. An actuating arrangement according to one of Claims 1 to 4, with a pump carrier comprising the pump and a reversing valve, characterized in that the non-return valve (23) and where appropriate the pressure-relief valve (26) is or are integrated in or on the pump carrier (25).