EP0803630A2 - Hydraulic operating device - Google Patents

Abstract

The operating device uses at least one double-action hydraulic cylinder (3) extending between the vehicle body and the boot lid, each of its pressure spaces (8,9) coupled to a hydraulic pressure source (12) via a non-return valve (10,11). The emergency opening of the boot lid can be facilitated by an emergency valve (17) connected to the line between one of the cylinder spaces (8) and its non-return valve (10), the emergency valve normally held in the closed position.

Description

The invention relates to an arrangement for the hydraulic actuation of a cover flap on a vehicle, with at least one double-acting hydraulic working cylinder, which is articulated on the one hand on the vehicle and on the other hand on the cover flap and the working spaces of which are each connected to one side of a switchable pressure source via a check valve, the two check valves have a mutual unlocking device and the two working spaces are connected in parallel to the check valves via a preload valve.

Such arrangements are known (see e.g. DE 43 34 843 A1) and enable, for example, the automatic actuation of vehicle doors, bonnets, maintenance flaps or also cover flaps of the trunk or a space accommodating a folding top. The mutually unlockable non-return valves ensure that when the operating pressure is switched off or fails, the cover flap remains hydraulically locked in the respective position in order to eliminate uncontrolled movements and the associated dangers. The preload valve enables the cover flap to be moved further in a controlled manner in this state, for example by hand, in order, for example, to permit emergency closing against a force specified by the preload valve.

A disadvantage of the known arrangement of the type mentioned is in particular the fact that the emergency actuation described is only possible in connection with a volume-balanced working cylinder, since there are otherwise problems with the removal or supply of hydraulic medium to the piston-side or rod-side working space. A simple control of the excess volume pushed out of the respective work area into the tank would still be possible - but there are problems with the supply of hydraulic medium to the other work area without pressure in an emergency, since on the one hand very thin, flexible lines are used for the application in vehicles which, on the other hand, are also due to the crowded accommodation options are relatively long, so that the after-sucking work space is at least partially filled with outgassing air. This then leads to the fact that after the manually operated cover flap has been left out, it can fall back undefined and cause damage and injuries.

The object of the present invention is to improve a known arrangement of the type described in the introduction in such a way that the disadvantages described are avoided and that, in particular in a simple and safe manner, an emergency actuation of the cover flap also in the case of the usual volumes of the working spaces which differ on the piston and rod side having working cylinders is possible.

This object is achieved in an arrangement of the type mentioned according to the invention in that between the piston-side working space and the unlockable check valve an emergency valve which switches to the tank when an adjustable pressure level is exceeded is switched on and can be hydraulically shut off via the pressure prevailing on the pump side in front of the associated check valve. If the hydraulic working pressure fails, a simple and safe emergency actuation of the cover flap is still possible, for example by hand. When the working cylinder is pulled out by hand, the rod-side working space volume is pushed into the larger-volume piston-side working space, whereby the missing differential volume in the piston-side working space can be accepted in the form of outgassing air, since this usually only makes up a few percent of the volume and the possibility that this gives the slight movement of the cover flap against this small air cushion does not interfere. When the working cylinder is pushed in by hand, the rod-side working chamber is completely filled from the larger piston-side working chamber; the excess volume is discharged into the tank via the emergency valve during the first emergency actuation of this type. With subsequent further emergency operations, a corresponding pushing is simply carried out in both cases between the work rooms, again the small difference described above is missing or accepted on the piston side. This results in a very simple and safe possibility for emergency actuation of arbitrarily designed working cylinders.

In a preferred embodiment of the invention it is provided that a non-return valve is arranged parallel to the bias valve opening when a preferably adjustable piston-side pressure level in the direction of the rod-side working chamber is exceeded, which opens when the pressure is applied accordingly in the direction of the piston-side working chamber. This can be achieved very easily, for example, when the cover flap opens with the working cylinder extending, that an emergency opening by hand is facilitated, since the opened check valve enables emergency actuation in the direction of the extending piston rod bypassing the preload valve practically unhindered. Depending on the setting of the opening pressure of the preload valve, the cover to be actuated can be supported in various positions against the effect of gravity, the pressure threshold set, however, also having an indirect influence on the closing force required for emergency actuation.

According to a further embodiment of the invention, a parallel arrangement of the throttle point and the check valve opening in the direction of the piston-side working chamber can be connected between the preload valve and the piston-side working chamber. On the one hand, this retracts the retraction or insertion of the working cylinder, also and especially in the case of emergency actuation via the throttle point of the parallel arrangement, in addition to the preload valve that specifies a threshold, and on the other hand, the parallel kickback ensures that the working cylinder is extended and pushed out practically hydraulically in the event of an emergency actuation will.

In a particularly preferred further embodiment of the invention it can be provided that preferably in the connection of the two work spaces Between the two parallel arrangements of preload valve and check valve on the one hand and throttle point and check valve on the other hand, a switchable seat valve is switched on. In the closed position in normal operation, this seat valve enables hydraulically completely separate control of the two work spaces - in emergency operation, the seat valve is open, which means that the described options for emergency actuation are unimpeded.

In a further embodiment of the invention, a preferably adjustable throttle point can be switched on on the control side of the emergency valve, which allows influencing the movement behavior of the working cylinder which is actuated for the first time in the direction of retracting in the manner described above.

According to another preferred development of the invention, it can finally be provided that a preferably adjustable throttle point is arranged in the connection between the rod-side work space and the associated unlockable check valve, which, in a simple manner during hydraulic closing due to the pressure drop, reliably opens the hydraulically unlockable check valve on the piston side guaranteed.

The invention is explained in more detail below with reference to the drawings. 1 shows a schematic arrangement according to the present invention in a vehicle and FIGS. 2 to 6 show a partially schematic, hydraulic circuit diagram of an arrangement according to the invention in various functional states.

The arrangement shown in FIG. 1 for the hydraulic actuation of a cover flap 1 on a vehicle 2 has at least one double-acting hydraulic working cylinder 3 which is articulated on the one hand on the vehicle 2 and on the other hand on the cover flap 1. The working spaces of the working cylinder 3, not shown here, are connected via lines 4, 5 to a hydraulic unit 6, which is connected via a connecting line 7 to the electrical system of the vehicle 2 is connected.

Instead of the direct articulation of the working cylinder 3 on both sides, which of course requires correspondingly movable lines 4, 5 or a hydraulic unit 6 which can be moved together with the working cylinder 3, the articulation of the working cylinder 3 on the vehicle and / or cover flap side could also take place indirectly via levers or the like , wherein the working cylinder 3 could also be fixed relative to the vehicle 2.

2 to 6, the combination of hydraulic unit 6 and working cylinder 3 connected via lines 4, 5 is shown in more detail.

The two working spaces 8, 9 of the working cylinder 3 are connected via the lines 4, 5 and a check valve 10, 11 arranged in the hydraulic unit 6, each with one side of a switchable pressure source 12 (here formed from a pump including the drive motor). The two check valves 10, 11 are connected via lines 13, 14 and can be unlocked from each other. The two working spaces 8, 9 are connected in parallel to the check valves 10, 11 via a preload valve 15. Between the piston-side working chamber 8 and the associated unlockable non-return valve 10, an emergency valve 17 which switches off when an adjustable pressure level to the tank 16 is exceeded is switched on and can be hydraulically shut off via a line 18 and the pressure prevailing on the pump side in front of the non-return valve 10. A non-return valve 19 is arranged parallel to the preload valve 15 which opens when a preferably adjustable piston-side pressure level in the direction of the rod-side working chamber 9 is opened, which opens when the pressure is applied accordingly in the direction of the piston-side working chamber 8. A parallel arrangement of throttle point 20 and check valve 21 opening in the direction of the piston-side working chamber 8 is also connected between the preload valve 15 and the piston-side working chamber 8. In the connection of the two working spaces 8, 9 is between the two parallel arrangements of bias valve 15 and check valve 19 on the one hand and throttling point 20 and check valve 21 on the other hand, an electrically switchable seat valve 22 is switched on, with which the two working spaces 8, 9 can be completely separated. A preferably adjustable further throttle point 23 is switched on on the control side of the emergency valve 17. A further, preferably adjustable, further throttle point 24 is finally arranged in the connection between the rod-side working space 9 and the associated unlockable check valve 11.

The connecting line 7 shown in FIG. 1, which is not shown separately in FIGS. 2 to 6, controls the motor of the pump of the pressure source 12, the poppet valve 22 and a shuttle valve 25 between the adjustable pressure relief valves 26, 27 leading to the tank 16 Cables. Furthermore, limit switches or other position controls, for example, could also supply signals to control units (not shown) or the like via this connecting line 7.

The function of the arrangement shown is explained below with reference to the individual actuation phases as shown in FIGS. 2 to 6.

1. Fig. 2: Hydraulic opening; Working cylinder 3 extends

The motor of the pump of the pressure source 12 is energized, the pump runs and supplies pressure medium via the check valves 10 and 21 into the piston-side working chamber 8. The seat valve 22 is also energized, which, as shown, the connection to the rod-side working chamber 9 is interrupted. The emergency valve 17 is controlled via the line 18. The pressure in the piston-side working space 8 can build up to the required value. The cover flap 1 (FIG. 1) opens hydraulically up to the stop in the working cylinder 3. The volume of the rod-side working space 9 flows through the check valve 11, which is hydraulically actuated via the line 14, and the shuttle valve 25 into the tank 16. Depending on the counterweight or counterforce on the cover flap 1, the hydraulic system delivers the total pressure on the pressure relief valve 26 adjustable force. The pump runs until the cover flap 1 is open and is then switched off. Furthermore, the seat valve 22 is also de-energized after the hydraulic opening, after which the cover flap 1 is held in the open position by the pressure which can be set on the emergency valve 17.

2. Fig. 3: Hydraulic closing; Working cylinder 3 retracts

The closing process described below can be divided into three phases, for example - apart from that, it is of course also possible to drive the entire closing process in only one phase, for example as shown in FIG. 3, or to omit the third phase described below.

In the first phase, as can be seen in FIG. 3, the motor of the pump of the pressure source 12 is energized, in which case pressure medium is now conveyed into the rod-side working space 9 via the check valve 11 and the throttle point 24. The seat valve 22 is in turn energized and closed. The lid 1 closes with an adjustable force on the pressure relief valve 27. The seat valve 22 blocks the connection to the piston-side working space 8. The volume flowing out of this flows because of the blocked backstroke 21 via the throttle point 20 and the check valve 10 via line 13 and the shuttle valve 25 into the tank 16. The throttle point 24 brings about a safe opening of the check valve 10 due to the improved pressure build-up. The closing force is set so that the cover flap 1 (Fig. 1) closes securely even when the associated vehicle is tilted or other unfavorable conditions. On the other hand, the closing force can not be set higher than on the pressure relief valve 27, which can easily be realized that the cover flap 1 can also be stopped by hand if necessary.

In a second phase of hydraulic closing, the motor of the pump of the pressure source 12 is still energized, while the seat valve 22 is de-energized and is switched to continuity. This can be provided for safety reasons, since it makes it possible to stop the cover flap 1 with much less effort. Since the pressure source 12 continues to deliver normally, a largely uniform downward movement is maintained and the rod-side working space 9 is sufficiently refilled. When the cover flap 1 stops, for example due to an obstacle, the pump volume flow that occurs flows through the check valve 11, the check valve 19, the then opened seat valve 22, the check valve 10 which is opened via the line 13 and the shuttle valve 25 into the tank 16.

In a third phase, the motor of the pressure source 12 and the seat valve 22 can in turn remain de-energized for safety reasons, so that the cover flap 1 according to FIG. 1 only sinks to the completely closed position due to its own weight. In the event of a stop, only the weight of the cover flap 1 occurs, thus eliminating any risk of injury. The flowing volume flow from the piston-side working chamber 8 flows partly through the throttle point 20, the then opened seat valve 22 and the bias valve 15 into the rod-side working chamber 9 and partly through the prestressed emergency valve 17 and the throttle point 23 into the tank 16 the filling of the rod-side working space 9 noises in the hydraulics are prevented when the cover flap 1 is subsequently reopened. The throttle point 20 brakes the closing movement of the cover flap 1 as a function of the speed, which further reduces the risk of injury. The emergency valve 17 counteracts the relatively strong counterforce of the cover flap 1 in this phase. With the throttle point 23, further fine-tuning of the closing speed of the cover flap 1 can be carried out.

3. Fig. 4: Stop function

The motor of the pump of the pressure source 12 is de-energized. The seat valve 22 is energized only briefly until the cover flap 1 is braked or has come to a standstill. Thereafter, the seat valve 22 is switched off, which is very advantageous in terms of energy consumption, for example of a vehicle battery. This stop function can take place at any time in the area of the first two phases of closing described above. The cover flap 1 is held by the pressure set on the emergency valve 17. In the arrangement of the cover flap 1 shown in FIG. 1, no separate stop function is provided in the third phase described above of the complete closing solely by the weight of the cover flap 1. However, this is not a disadvantage since, as described, the cover flap 1 can also be easily stopped by hand in this phase.

4. Fig. 5: Emergency function - opening the cover flap 1 by hand, for example if the pressure source 12 fails due to a lack of power supply.

The cover flap 1 can be opened with relatively little effort. Only the weight of the cover flap 1 itself and the flow resistance in the hydraulic system have to be overcome. Gas springs that may be installed in the vehicle and act on the cover flap 1 provide additional support. As can be seen, the pressure medium flows from the rod-side working chamber 9 almost without pressure and therefore with little effort via the check valve 19, the poppet valve 22 and the check valve 21 into the piston-side working chamber 8 and fills it up. This is extremely important so that the cover flap 1 also remains standing after such an emergency actuation and cannot fall back against an air cushion in this work space 8, which could represent a great safety risk. As a result of the negative pressure when the piston-side working space is not filled, air would be released from the pressure medium. The difference volume that is naturally missing in this way when filling the piston-side working space due to the smaller volume of the rod-side working space 9 is only a few percent and is insignificant in terms of safety.

5. Fig. 6: Emergency function - closing the cover flap 1 by hand

This is again necessary, for example, if the pump drive fails. As shown, the volume flow flows from the piston-side working chamber 8 via the throttle point 20, the seat valve 22 and the biasing valve 15 into the rod-side working chamber 9 and fills it up. The throttle point 20 has the function of braking harder if the closing speed is too fast than if the closing speed is slow. The preload valve 15 acts against the weight of the cover flap 1. When this type of emergency actuation is carried out for the first time, the excess differential volume flow of the working cylinder 3 can flow out via the emergency valve 17. It should also be mentioned that the pressure set at this emergency valve 17 is higher than that at the preload valve 15.

Apart from the illustrated and described arrangement and actuation of a cover flap 1 according to FIG. 1 (for example on a trunk or the bonnet of a car), the arrangement according to the invention could of course also be used to actuate tailgates which are vertical in the closed state, for example a station wagon or a bus. Other application examples would be e.g. Vehicle doors, maintenance or ventilation flaps and the like.

Claims (6)

Arrangement for the hydraulic actuation of a cover flap on a vehicle, with at least one double-acting hydraulic working cylinder, which is articulated on the one hand on the vehicle and on the other hand on the cover flap and whose working spaces are connected via a check valve to one side of a switchable pressure source, the two check valves have a mutual unlocking device and the two working spaces are connected parallel to the check valves via a preload valve, characterized in that between the piston-side working space (8) and the unlockable non-return valve (10) an emergency valve (17) which shuts off when an adjustable pressure level to the tank (16) is exceeded is switched on, which can be shut off hydraulically via the pressure prevailing on the pump side in front of the associated check valve (10). Arrangement according to claim 1, characterized in that a non-return valve (19) is arranged parallel to the preload valve (15) which opens in the direction of the rod-side working chamber (9) when a preferably adjustable piston-side pressure level is exceeded, which check valve (19) in the direction of the piston-side working chamber when the pressure is applied accordingly (8) opens. Arrangement according to claim 1 or 2, characterized in that a parallel arrangement of the throttle point (20) and the check valve (21) opening in the direction of the piston-side working chamber (8) opens between the preload valve (15) and the piston-side working chamber (8). Arrangement according to one or more of claims 1 to 3, characterized in that in the connection of the two working spaces (8, 9), Preferably between the two parallel arrangements of the bias valve (15) and the check valve (19) on the one hand and the throttle point (20) and the check valve (21) on the other hand, a switchable seat valve (22) is switched on. Arrangement according to one or more of claims 1 to 4, characterized in that a preferably adjustable throttle point (23) is switched on on the control side of the emergency valve (17). Arrangement according to one or more of claims 1 to 5, characterized in that a preferably adjustable throttle point (24) is arranged in the connection between the rod-side working space (9) and the associated unlockable check valve (11).

Images