Drive arrangement for a flap of a motor vehicle

Abstract

Drive arrangement for a flap (2) of a motor vehicle with at least one motor drive (3) and with at least one gas pressure element (4), in particular with a gas spring, wherein the gas pressure element (4) has an externally sealed cylinder (6) and a piston (8) running in the cylinder interior (7) along the cylinder axis (A), dividing the cylinder interior (7) into two partial spaces (7a, 7b), wherein the piston (8) has an overflow channel arrangement (9) through which a compensating flow is created between the two sub-spaces (7a, 7b) in response to a piston movement, wherein the gas pressure element (4) has a first drive connection (4a) which is connected to the cylinder (6) and a second drive connection (4b) which is connected to the piston (8), wherein the cylinder (6) is filled with a fluid, in particular under pressure, characterized by that the piston (8) is associated with a switchable valve arrangement (10) which can be brought into a closed state in which it at least partially, preferably completely, closes the overflow channel arrangement (9) and into an open state in which it opens the overflow channel arrangement (9), that the overflow channel arrangement (9) automatically switches to the closed state in the event of a compensating flow, in particular an emergency flow, which exceeds a predetermined switching flow, that the piston (8) has a base body (8b) which is at least partially sealed against the inner surface of the cylinder and which provides part of the overflow channel arrangement (9), that the valve arrangement (10) has a valve body (11) which is arranged on the base body (8b) and which is adjustable relative to the base body (8b) into a closed position corresponding to the closed state and into an open position corresponding to the open state, and that the overflow channel arrangement (9) has at least two partial channels (9a, 9b), one of which is provided by the base body (8b) and one of which is provided by the valve body (11), and that the valve arrangement (10) in the closed state closes at least one of the partial channels (9a, 9b).

Description

[0001] The invention relates to a drive arrangement for a flap, in particular a tailgate, of a motor vehicle according to the preamble of claim 1, and to a flap arrangement comprising a flap, in particular a tailgate, and such a drive arrangement according to claim 10.

[0002] The drive system in question is used for the motorized adjustment of any locking elements of a motor vehicle. Such locking elements can include, for example, tailgates, trunk lids, hoods, cargo floors, and even doors. In this context, the term "flap" is to be interpreted broadly.

[0003] The known drive arrangement (DE 10 2008 057 014 A1), from which the invention is based, serves for the motorized adjustment of a motor vehicle's tailgate. The drive arrangement has a motorized drive in the form of a spindle drive on one side of the tailgate. This spindle drive comprises an electric drive unit and a spindle-spindle nut drive connected downstream of the electric drive unit. This drive generates linear drive movements between a body-side drive connection and a tailgate-side drive connection for opening and closing the tailgate. In the open position of the tailgate, the spindle drive is in an extended position, whereas in the closed position of the tailgate, the spindle drive is in a retracted position. Such a drive arrangement is also known from DE 10 2014 105 624 A1.Further drive arrangements for adjusting a flap of a motor vehicle are described in DE 103 39 188 A1, DE 10 2005 044 578 B3 and DE 10 2011 006 011 A1.

[0004] Since the weight of the tailgate can be considerable, a gas spring is positioned separately from the spindle drive on the other side of the tailgate to compensate for its weight. This is generally intended to ensure that the tailgate is always near equilibrium or is gently pushed in the opening direction. Such a tailgate arrangement, with a motorized drive on one side and a gas spring on the other, is also referred to as an active / passive system.

[0005] The invention is based on the problem of designing and further developing the known drive arrangement in such a way as to create another possibility to counteract the weight force of a corresponding flap.

[0006] The above problem is solved in a drive arrangement according to the preamble of claim 1 by the features of the characterizing part of claim 1.

[0007] The essential consideration is to provide a gas pressure element that has a switchable valve arrangement, allowing the gas pressure element to automatically switch from normal operation to emergency operation.

[0008] In this context, a gas pressure element generally refers to an element comprising a cylinder and a piston guided coaxially to the cylinder axis. This element provides pneumatic and / or hydraulic pressure, particularly static and / or dynamic pressure, between the cylinder and the piston of the gas pressure element, whether the piston is stationary or moving relative to the cylinder. The cylinder is filled with at least one fluid, in particular a gas and / or a liquid. The gas and / or liquid may be pressurized (i.e., at a pressure above or below ambient pressure) or unpressurized (i.e., at a pressure essentially equal to ambient pressure).Preferably, the gas pressure element is formed solely by a gas spring, in particular a gas compression or gas tension spring, i.e., a cylinder-piston arrangement in which the piston is filled with a fluid under pressure, in particular overpressure. The gas pressure element can also be formed by a gas damper, i.e., a cylinder-piston arrangement in which the piston is filled with a fluid without pressure. The gas pressure element can also comprise such a cylinder-piston arrangement, in particular a gas spring and / or a gas damper, as one component, and additionally, as a further component, a spring arrangement acting parallel or coaxially to the cylinder axis and thus in the direction of action of the gas pressure element, the gas spring, or the gas damper. Therefore, the terms "gas pressure element," "gas spring," and "gas damper" are to be interpreted broadly.

[0009] In normal operation, the gas spring or gas damper of the proposed gas pressure element functions like a conventional gas spring or gas damper, which, in the usual manner, has a fluid-filled cylinder, in particular a gas and / or liquid-filled cylinder, and a piston guided within the cylinder. The gas pressure element thus utilizes the compressibility of the filled fluid, especially gas, for its spring-like or damping effect. In a gas spring, the pressurized fluid presses against the cross-sectional area of ​​the piston, thereby driving the cylinder-side drive connection and the piston-side drive connection, through which the gas spring is coupled to the vehicle, apart. If the gas spring is subjected to a force exceeding that defined by the filling pressure and the cross-sectional area of ​​the piston, the two drive connections are driven towards each other.In a gas damper, where the fluid is therefore unpressurized, the actuator connections are movable relative to each other by an external movement introduced into the gas pressure element, for example, by manually or via a motorized actuator operating the tailgate. This pressurizes the fluid across the cross-sectional area of ​​the piston. The piston, in particular its base body also referred to as the piston head, divides the cylinder interior into two compartments in both gas springs and gas dampers. A transfer channel arrangement, which is formed at least partially by the base body, allows the fluid to flow from one compartment to the other. This flow is subsequently referred to as the compensating flow.

[0010] In emergency mode, the valve assembly automatically closes at least partially, preferably completely, the overflow channel assembly, i.e., one or more partial channels provided by the overflow channel assembly, thereby slowing or blocking movement of the actuator connections relative to each other, particularly towards each other. The valve assembly automatically switches from normal operation to emergency mode when the compensating flow exceeds a predetermined switching flow, in particular when a limit value for the compensating flow velocity is reached. The automatic switching of the valve assembly is thus achieved by an increase in the flow or its flow velocity to a specific limit value.

[0011] Specifically, it is proposed that the piston is associated with a switchable valve arrangement which can be brought into a closed state, in which it at least partially, preferably completely, closes the overflow channel arrangement, and into an open state, in which it opens the overflow channel arrangement; and that the overflow channel arrangement automatically switches to the closed state in the event of a compensating flow, particularly in the case of an emergency, which exceeds a predetermined switching flow; that the piston has a base body which is at least partially sealed against the inner surface of the cylinder and which provides a part of the overflow channel arrangement; that the valve arrangement has a valve body which is arranged on the base body and which is adjustable relative to the base body into a closed position corresponding to the closed state and into an open position corresponding to the open state.and that the overflow channel arrangement has at least two partial channels, one of which is provided by the base body and one by the valve body, and that the valve arrangement in the closed state closes at least one of the partial channels. The proposed drive arrangement thus makes it possible to slow down and / or block the closing movement of a flap, in particular a tailgate, of a motor vehicle via the switchable valve arrangement. Even a relatively large weight force on a flap can be counteracted particularly easily in this way, so that the flap can be held in an open position or at least its closing movement can be significantly slowed down.

[0012] According to the embodiment of claim 2, the gas pressure element comprises a spring arrangement with at least one helical spring, in particular a compression or tension spring. The spring arrangement acts parallel or coaxially to the cylinder axis and thereby preloads, in particular, the drive connections relative to one another. Preferably, the drive connections are thereby driven apart or towards each other. A spring arrangement can be provided, among other things, when the gas pressure element has a gas damper, i.e., the cylinder-piston arrangement itself has no spring effect. However, it is generally preferred to provide a spring arrangement in combination with a gas spring. Preferably, the respective helical spring is arranged parallel or coaxially to the cylinder, in particular radially surrounding it.

[0013] According to the embodiment of claim 3, the switching flow that causes the automatic switching of the valve arrangement corresponds to a piston speed in the range between 20 mm / s and 200 mm / s, preferably between 40 mm / s and 70 mm / s, and particularly 50 mm / s. "Piston speed" refers to the speed at which the piston moves linearly relative to the cylinder. At a lower piston speed than the aforementioned, the compensating flow is so low that the valve arrangement remains in an open state, in which the overflow channel arrangement remains open. Reaching the respective limit value that defines the switching flow then leads, in particular, directly to the switching or activation of the valve arrangement and thus to the partial or complete closing of the overflow channel arrangement.

[0014] As proposed, the overflow channel arrangement has at least two sub-channels, at least one of which is at least partially, preferably completely, closed when the valve arrangement is closed (i.e., when activated). A first sub-channel extends through the piston body or between the piston body and the inner cylinder surface, and a second sub-channel extends through a valve body of the valve arrangement or between the valve body and the inner cylinder surface. In principle, all sub-channels can also be at least partially, preferably completely, closed when the valve arrangement is in the closed state.

[0015] According to the preferred embodiment of claim 4, the automatic switching of the valve arrangement to the closed state occurs only in a single adjustment direction of the gas pressure element, i.e., only in a single direction of movement of the actuator connections relative to each other. This adjustment direction corresponds in particular to the closing direction of the flap, which corresponds to a movement of the actuator connections towards each other.

[0016] Claims 5 to 9 define particularly preferred embodiments in which the valve arrangement comprises a valve body that is arranged on the base body of the piston, in particular the front end of the piston referred to as the piston head, and which is adjustable relative to the base body into a closing position corresponding to the closed state and into an open position corresponding to the open state. The valve body is preferably biased in the opening direction of the valve arrangement, in particular by spring bias (claim 6). Particularly preferred is the valve body being bistable and spring biased (claim 7), that is, the valve body is biased in the closing direction in its closed position and in the opening direction in its open position.This has the advantage that the valve arrangement remains activated after the compensating flow exceeds the switching flow, at least until the valve arrangement is deactivated again, i.e., until a switch to normal operation occurs. The latter can be achieved, for example, by manually actuating the valve against the direction of movement of the gas pressure element that caused the closed state, i.e., in particular, in the opening direction of the valve. Instead of a separate spring that bistablely preloads the valve body, the valve body itself can be designed as an elastic diaphragm that is deformable in two stable positions, with the diaphragm defining the open state in one position and the closed state of the switchable valve arrangement in the other.

[0017] According to a further teaching as claimed in claim 10, which has independent significance, a flap arrangement is claimed as such, comprising a flap, in particular a tailgate, and a proposed drive arrangement associated with the flap. Reference may be made to all embodiments of the proposed drive arrangement. The flap is preferably pivotable about a flap axis which, in the assembled state, is oriented substantially horizontally.

[0018] According to the preferred embodiment of claim 11, an emergency that causes the compensating flow to exceed a predetermined switching flow is defined in that the driving force and / or holding force of the drive fails and thereby forces the flap in the closing direction or in the opening direction due to spring force and / or gravity, and that the emergency switching of the valve arrangement into the closed state counteracts any further adjustment of the flap, in particular blocks any further adjustment of the flap (claim 11).

[0019] The gas pressure element preferably pre-tensions the flap, particularly in its opening direction (claim 12). In particular, it is provided that the flap assembly has the actuator, in particular exactly one actuator, on a first side of the flap, and the gas pressure element, in particular exactly one gas pressure element, on the opposite, second side. In this respect, it is in particular an active / passive system. The actuator is preferably designed as a linear actuator, in particular a spindle actuator.

[0020] According to the embodiment of claim 13, the switching flow that causes the valve arrangement to switch into the closed state corresponds to a velocity of the outer edge of the flap in a range between 0.5 m / s and 3.0 m / s, preferably between 0.8 m / s and 1.2 m / s, in particular of 1.0 m / s.

[0021] The invention will now be explained in more detail with reference to a drawing that merely illustrates exemplary embodiments. The drawing shows Fig. 1 the rear area of ​​a motor vehicle with a proposed flap arrangement, which is equipped with a proposed drive arrangement, Fig. 2 a sectional view of a gas pressure element in a first embodiment of the drive arrangement according to Fig. 1 in normal operation and in emergency operation and Fig. 3 a sectional view of a gas pressure element in a second embodiment of the drive arrangement according to Fig. 1 in normal operation and in emergency operation.

[0022] The proposed drive arrangement 1 serves to adjust a flap 2 of a motor vehicle by means of a motor vehicle. The flap 2 can be adjusted in an opening direction and / or in a closing direction by means of the drive arrangement 1.

[0023] The flap 2 is, in this context, preferably a tailgate of a motor vehicle. The proposed drive arrangement 1 can be used particularly advantageously in the application of a tailgate, since tailgates have a comparatively high weight.

[0024] In principle, the proposed drive arrangement 1 can also be applied to other types of flaps 2 of a motor vehicle. These include tailgates, hoods, and the like, as well as doors. All designs apply accordingly to other flaps.

[0025] How Fig. As shown in Figure 1, the proposed drive arrangement 1 here, and preferably, comprises exactly one motorized drive 3 and exactly one gas pressure element 4. The motorized drive 3 is, as will be explained in more detail below, here, and preferably, a linear drive, in particular a spindle drive. The gas pressure element 4 is here, and preferably, a gas spring, in particular a gas pressure spring. Here, and preferably, the gas spring pre-tensions the flap 2 in its opening direction.

[0026] The gas spring can also be a gas tension spring. It is also conceivable that the gas pressure element 4 is a gas damper, i.e., it does not have a spring effect. In this case, but also in principle in the case of a gas spring, the gas pressure element 4 can additionally have a spring arrangement that generates a spring force parallel or coaxial to its direction of action.

[0027] In the embodiments described here, a gas spring is provided as an example of a gas pressure element 4. However, the statements regarding this apply equally to the other gas pressure elements 4 mentioned.

[0028] The proposed drive arrangement 1 can, in principle, also have more than one motor drive and / or more than one gas pressure element 4. In the case of the Fig. In the flap arrangement 5 shown in Figure 1, which also includes the drive arrangement 1 in addition to the flap 2 of the motor vehicle, the motor drive 3 is arranged on a first side of the flap 2 and the gas pressure element 4 or, in this case, the gas spring, is arranged on an opposite, second side of the flap 2.

[0029] The motorized drive 3, which here forms the active side of an active / passive system, is configured to open and close the flap 2. For this purpose, the drive 3 comprises a drive unit (not shown) with an electric drive motor and optionally one or more further drive components such as an intermediate gearbox, an overload clutch, and / or a brake. A linear drive unit, preferably also not shown, is connected downstream of the drive unit. This linear drive unit comprises, in particular, a spindle and a spindle nut meshing with it. Here, and preferably, the spindle is coupled to the drive unit and is set into rotation during operation, causing the spindle nut to perform a linear movement along the spindle.

[0030] The motorized drive 3, comprising the drive unit and the linear drive, in particular a spindle-spindle nut drive, has a first drive connection 3a, in particular on the spindle side, and a second drive connection 3b, in particular on the spindle nut side, via which the drive 3 is coupled to the motor vehicle. Here, and preferably, the drive 3 is coupled to the flap 2 via the spindle-side drive connection 3a and to the body of the motor vehicle via the spindle-side drive connection 3b. The linear drive movements of the linear drive either move the drive connections 3a and 3b apart, which corresponds to an adjustment movement of the flap 2 in its opening direction, or they move the drive connections 3a and 3b together, which corresponds to an adjustment movement of the flap 2 in its closing direction.

[0031] The gas spring, which here preferably forms the gas pressure element 4 and constitutes the passive side of the active / passive system, has no drive mechanism of its own, but rather provides a spring function. The gas spring is intended to absorb part of the weight of the flap 2 and thereby hold the flap 2, when open, near its equilibrium state or to push it in the opening direction.

[0032] The gas spring comprises, in a conventional manner, an externally sealed cylinder 6 and a piston 8 running along the cylinder axis A within the interior space 7 enclosed radially by the cylinder 6, dividing the cylinder interior 7 into two compartments 7a and 7b. The piston 8 has a piston rod 8a that runs along the cylinder axis A and is movable relative to the cylinder 6. The piston rod 8a seals through an axial opening in the cylinder 6, so that one section of the piston rod 8a is located inside the cylinder interior 7 and another section is located outside the cylinder 6. The piston 8 also has a base body 8b at the section of the piston rod 8a located inside the cylinder interior 7, particularly at its front end, which forms the piston head.

[0033] The base body 8b preferably has a cross-section, measured in a radial direction, that largely corresponds to that of the cylinder interior 7. "Largely" means that the base body 8b of the piston 8 completely closes the cross-section of the cylinder interior 7, except for a channel 9a, which is particularly annular or consists of several adjacent individual channels. The channel 9a is one of at least two fluidically connected sub-channels 9a, 9b, which are part of a transfer channel arrangement 9, through which a compensating flow is generated between the two sub-chambers 7a, 7b in response to piston movement. Here, and preferably, the sub-channel 9a is bounded radially to the direction of flow through which the compensating flow passes by it, by the radial inner surface of the cylinder 6 on the one hand and by the radial outer surface of the base body 8b on the other.Such a configuration of the overflow channel arrangement 9 is shown in the embodiment according to . Fig. 2 are planned.

[0034] Additionally or alternatively, the partial channel 9a of the overflow channel arrangement 9 can also extend through the base body 8b as a channel or a plurality of parallel individual channels along the cylinder axis A, as in the embodiment shown in the figure. Fig. 3 is provided. In the latter case, the channel or each individual channel is therefore completely surrounded laterally by the material of the base body 8b and is formed, for example, by a bore.

[0035] In both cases, the cylinder 6 is filled with a fluid that is present in both sub-chambers 7a and 7b and can flow through the sub-channels 9a and 9b of the overflow channel arrangement 9 between the sub-chambers 7a and 7b as part of the aforementioned compensating flow. The fluid is, in particular, a compressible gas and may optionally, preferably in small quantities, also contain a liquid such as oil, for example, to provide end-position damping.

[0036] The gas spring further comprises a first drive connection 4a, which is connected to the cylinder 6, and a second drive connection 4b, which is connected to the piston 8. The cylinder 6 is filled with pressurized fluid in such a way that the two drive connections 4a and 4b are forced apart. In the unloaded state, i.e., when no external forces act on the gas spring, the two drive connections 4a and 4b of the gas spring are therefore in their maximum separated position, which is described in the Fig. 2 and Fig. 3 for the respective embodiment is shown in the left-hand illustration. This position of the drive connections 4a, 4b relative to each other also corresponds here and preferably to that shown in Fig. Figure 1 shows the flap 2 in its open position. The cylinder-side drive connection 4a is coupled to the flap 2, and the piston-side drive connection 4b is coupled to the vehicle body. It should be emphasized again that, as explained previously, the cylinder 6 can also be unpressurized, namely in the case of a gas damper instead of a gas spring.

[0037] In normal operation, when an external force drives the drive connections 4a, 4b together, for example during motorized or manual closing of flap 2, the piston 8 moves relative to the cylinder 6 from the position in the Fig. 2 and Fig. 3 is deflected in each of the positions shown on the left, namely in the direction of the Fig. 2 and Fig. 3 in the position shown in the right-hand illustration. The section of the piston 8 located in the cylinder interior 7 thus moves along the cylinder axis A through the cylinder interior 7, causing the two sub-chambers 7a, 7b of the cylinder interior 7 to change their volume. As the Fig. 2 and Fig. As can be seen in Figure 3, in the embodiments chosen here, when the drive connections 4a and 4b are brought together, the volume of sub-space 7a decreases, while the volume of sub-space 7b increases. As shown in the detailed view of the left-hand illustration in the Fig. 2 and Fig. Figure 3 shows the fluid flowing as a compensating flow from the upper sub-chamber 7a into the lower sub-chamber 7b through the partial channels 9a, 9b of the overflow channel arrangement 9. Since the fluid is filled into the cylinder 6 here, and preferably under pressure, the fluid presses on the cross-sectional area of ​​the piston 8, here the base body 8b, and thereby constantly pushes the piston 8 relative to the cylinder 6 into the position that is in the Fig. 2 and Fig. Figure 3 on the left illustrates this. The reason for this is that the cross-sectional area of ​​the piston 8 or base body 8a is larger on the side facing away from the piston, i.e., towards the sub-chamber 7a, than on the opposite side. This is because on the opposite side, the cross-sectional area subjected to the fluid pressure is formed only by a ring surrounding the piston rod 8a. The ring area effective on the side of sub-chamber 7b is smaller than the area effective on the side of sub-chamber 7a, which corresponds to the entire cross-section of the cylinder interior 7. Consequently, a greater pressure force acts on the piston 8 or base body 8b from the side of sub-chamber 7a than from the other side, causing the piston 8 to be constantly pushed out of the cylinder 6.

[0038] It is essential that the piston 8 is associated with a switchable valve arrangement 10, which can be brought into a closed state, in which it at least partially, preferably completely, closes the overflow channel arrangement 9, and into an open state, in which it opens the overflow channel arrangement 9, and that the overflow channel arrangement 9 automatically switches to the closed state in the event of a compensating flow, particularly in the case of an emergency, which exceeds a predetermined switching flow. As mentioned, this applies both to the use of a gas spring and a gas damper, optionally also in combination with an additional spring arrangement acting in the direction of action of the gas spring or gas damper.

[0039] The switchable valve arrangement 10 provides a means by which the gas spring can automatically switch from normal operation to emergency operation. An emergency occurs, for example, if the speed at which the flap 2 is moved between its open and closed positions, particularly when closing, exceeds a certain limit, i.e., if the closing movement is increased. The increased speed of the flap 2, in turn, increases the flow velocity of the compensating flow passing through the overflow channel arrangement 9. Consequently, the dynamic pressure in the piston-remote compartment 7a rises, and the dynamic pressure in the piston-rod-side compartment 7b falls, until the valve arrangement 10 switches from the open to the closed state, particularly upon reaching a predetermined pressure differential (switching pressure differential).In the closed state, the overflow channel arrangement 9 is then either partially closed, so that a linear movement of the piston 8 relative to the cylinder 6 is at least slowed down, or completely closed, so that the linear movement of the piston 8 relative to the cylinder 6 is blocked, at least after reaching a certain compression of the fluid in the subspace 7a.

[0040] The predetermined switching flow, the exceedance of which switches the valve arrangement 10 to the closed state, thus activating the valve arrangement 10, preferably corresponds to a piston speed in the range between 20 mm / s and 200 mm / s, preferably between 40 mm / s and 70 mm / s, and in particular a piston speed of 50 mm / s. With respect to the flap 2 itself, the switching flow can be configured to correspond to a speed of the outer edge of the flap 2 in the range between 0.5 m / s and 3.0 m / s, preferably between 0.8 m / s and 1.2 m / s, and in particular 1.0 m / s. At a lower piston speed or edge speed, the gas spring operates normally.

[0041] Here, and preferably, the overflow channel arrangement 9 has, as mentioned, at least two partial channels 9a, 9b, one of which partial channel 9a is located between the base body 8b and the cylinder 6 ( Fig. 2) or within the base body 8b ( Fig. 3) is formed. A further partial channel 9b is formed here, in particular, in a separate valve body 11. Thus, the valve arrangement 10 here and preferably has a valve body 11 which is arranged on the base body 8b of the piston 8 and which is adjustable relative to the base body 8b into a closed position, corresponding to the closed state of the valve arrangement 10, and into an open position, corresponding to the open state of the valve arrangement 10. Comparing the respective left and right illustrations in Fig. 2 and in Fig. 3 it can be seen that the partial channel 9a provided by the base body 8b is closed in the activated state of the valve arrangement 10 by the contact of the valve body 11 with the base body 8b.

[0042] Here, and preferably, the partial channel 9b provided by the valve body 11 extends through the valve body 11 as a channel or a plurality of parallel individual channels along the cylinder axis A. The channel, or each individual channel, is thus completely surrounded laterally by the material of the valve body 11 and is formed, for example, by a bore. However, it would also be conceivable that the partial channel 9b is bounded radially to the flow direction through which the compensating flow passes by it, by the radial inner surface of the cylinder 6 on the one hand and by the radial outer surface of the valve body 11 on the other.

[0043] The automatic switching of the valve assembly 10 to the closed state occurs here, and preferably only, in a single adjustment direction of the gas spring, which here, and preferably, corresponds to the closing direction of the flap 2. Only in this direction, when the compensating flow exceeds the predetermined switching flow, is the valve assembly 10 closed, in particular the valve body 11 pressed against the base body 8b of the piston 8. For other applications, however, other designs of the valve assembly 10 are conceivable in principle. Here, and preferably, the valve body 11 is arranged in the compensating flow such that, when the switching flow is exceeded, particularly in an emergency, the compensating flow, especially due to the dynamic pressure resulting from the compensating flow, moves the valve body 11 from the open position to the closed position.

[0044] For this purpose, in the embodiment according to Fig. 2. The valve body 11 is guided along the cylinder axis A on the base body 8b. The valve body 11 is thus displaceable relative to the base body 8b. Here, and preferably, the valve body 11 is a substantially plate-shaped, non-deformable element that is axially movable coaxially to the cylinder axis A along the piston 8. Here, and preferably, the valve body 11 is pre-tensioned in the opening direction of the valve assembly 10, here by means of a spring assembly 12. In this way, the valve body 11 is always pressed into the position corresponding to the open state of the valve assembly 10.

[0045] Preferably, after the valve arrangement 10 automatically switches to the closed position, the valve body 11 remains in the closed position as long as the difference in static pressure between the two partial chambers 7a, 7b of the cylinder 6 exceeds a switching pressure differential. Due to tolerance-related or defined leaks, the difference in static pressure may fall below a limit value for the switching pressure differential after some time, causing the valve arrangement 10 to return to the open state. This preferably occurs so slowly that the flap 2 only gradually continues to lower in the closing direction.

[0046] It can also be provided that the valve body 11 is bistablely spring-loaded such that, when it is in the closed position, it is biased in the closing direction of the valve assembly 10, in particular spring-loaded, and when it is in the open position, it is biased in the opening direction of the valve assembly 10, in particular spring-loaded. This can be achieved in particular by the spring assembly 12 having a tilting spring acting on the valve body.

[0047] A preload of the valve body 11 in the closed position in the closing direction of the valve assembly 10 has the advantage that the valve assembly 10, activated particularly in an emergency, cannot readily return to the open state. The latter is preferably only possible by manually actuating the flap 2 against the direction of adjustment in which the valve assembly 10 was previously activated, in particular by manually actuating the flap 2 in its opening direction.

[0048] The latter can be achieved, as shown in the exemplary embodiment according to Fig. 3. This is achieved in particular by designing the valve body 11 as an elastic diaphragm 13 that can be deformed into two stable positions. In this respect, the valve body 11 itself then forms a tilting spring. If, as in Fig. As shown in Figure 3 on the left, when the valve body 11 is in the open position, it assumes a shape by which it is biased in the opening direction of the valve assembly 10. If, as shown in Figure 3, the valve body 11 is in the open position, it then assumes a shape that biases it in the opening direction of the valve assembly 10. Fig. As shown in the right-hand illustration (3), when the valve body 11 is in the closed position, it assumes a shape by which it is biased in the closing direction of the valve assembly 10. Preferably, the diaphragm 13 has different conical shapes in the two stable positions, in particular conical shapes that open in opposite directions.

[0049] According to a further teaching, which has independent significance, a flap arrangement 5 is claimed, comprising a flap 2, in particular a tailgate, and a proposed drive arrangement 1. Reference may be made to all descriptions of the proposed drive arrangement 1.

[0050] In particular, this involves a flap 2 that is pivotable about a flap axis X, which is essentially horizontally oriented in the mounted state. As previously explained, the proposed drive arrangement 1 is particularly advantageous in this application. This is especially true in an emergency situation, as previously described, where the speed of the flap 2 is increased.

[0051] In the proposed flap arrangement 5, an emergency is defined in particular by the fact that the driving force and / or holding force of the drive 3 fails and thereby the flap 2 is forced in the closing direction or in the opening direction due to spring force and / or gravity, that the emergency switching of the valve arrangement 10 into the closed state counteracts a further adjustment of the flap 2 and in particular blocks a further adjustment of the flap 2.

Claims

[1] Drive arrangement for a flap (2) of a motor vehicle with at least one motor drive (3) and with at least one gas pressure element (4), in particular with a gas spring, wherein the gas pressure element (4) has an externally sealed cylinder (6) and a piston (8) running in the cylinder interior (7) along the cylinder axis (A) and dividing the cylinder interior (7) into two partial spaces (7a, 7b), wherein the piston (8) has an overflow channel arrangement (9) through which a compensating flow is created between the two sub-spaces (7a, 7b) in response to a piston movement, wherein the gas pressure element (4) has a first drive connection (4a) which is connected to the cylinder (6) and a second drive connection (4b) which is connected to the piston (8), wherein the cylinder (6) is filled with a fluid, in particular under pressure, characterized by , that the piston (8) is associated with a switchable valve arrangement (10) which can be brought into a closed state in which it at least partially, preferably completely, closes the overflow channel arrangement (9) and into an open state in which it opens the overflow channel arrangement (9), that the overflow channel arrangement (9) automatically switches to the closed state in the event of a compensating flow, in particular an emergency flow, which exceeds a predetermined switching flow, that the piston (8) has a base body (8b) which is at least partially sealed against the inner surface of the cylinder and which provides part of the overflow channel arrangement (9), that the valve arrangement (10) has a valve body (11) which is arranged on the base body (8b) and which is adjustable relative to the base body (8b) into a closed position corresponding to the closed state and into an open position corresponding to the open state, and that the overflow channel arrangement (9) has at least two partial channels (9a, 9b), one of which is provided by the base body (8b) and one of which is provided by the valve body (11), and that the valve arrangement (10) in the closed state closes at least one of the partial channels (9a, 9b). [2] Drive arrangement according to claim 1, characterized by that the gas pressure element (4) has a spring arrangement with at least one helical spring, in particular a helical compression spring or a helical extension spring, preferably that the helical spring is arranged parallel or coaxial to the cylinder (6), in particular radially surrounding it. [3] Drive arrangement according to claim 1 or 2, characterized by that the switching flow corresponds to a piston velocity in a range between 20 mm / s and 200 mm / s, preferably between 40 mm / s and 70 mm / s, in particular 50 mm / s. [4] Drive arrangement according to one of the preceding claims, characterized by, that the automatic switching of the valve arrangement (10) into the closed state is provided only in a single adjustment direction of the gas pressure element (4), in particular in an adjustment direction of the gas pressure element (4) corresponding to the closing direction of the flap (2). [5] Drive arrangement according to one of the preceding claims, characterized by , that the valve body (11) is arranged in the compensating flow in such a way that, in the event of an exceedance of the switching flow, particularly due to the dynamic pressure resulting from the compensating flow, the compensating flow transfers the valve body (11) from the open position to the closed position. [6] Drive arrangement according to one of the preceding claims, characterized by , that the valve body (11) is guided along the cylinder axis (A) on the base body (8b). [7] Drive arrangement according to one of the preceding claims, characterized by, that the valve body (11) is pre-tensioned in the opening direction of the valve arrangement (10), in particular spring-tensioned, preferably that after the automatic switching of the valve arrangement (10) into the closed state the valve body (11) remains in the closed position as long as the difference in static pressure between the two partial chambers (7a, 7b) of the cylinder (6) exceeds a switching pressure difference. [8] Drive arrangement according to one of the preceding claims, characterized by , that the valve body (11) is bistablely spring-loaded such that the valve body (11) in the closed position is biased in the closing direction of the valve arrangement (10) and the valve body (11) in the open position is biased in the opening direction of the valve arrangement (10). [9] Drive arrangement according to one of the preceding claims, characterized by, that the valve body (11) is designed as an elastic membrane (13) which is deformable in two stable positions, preferably that the membrane (13) has different conical shapes in the two stable positions, in particular opening in opposite directions. [10] Flap arrangement comprising a flap (2), in particular a tailgate, and a drive arrangement (1) associated with the flap (2) according to one of the preceding claims. [11] Valve arrangement according to claim 10, characterized by, that an emergency is defined by the fact that the driving force and / or holding force of the drive (3) fails and thereby the flap (2) is forced in the closing direction or in the opening direction due to spring force and / or gravity, that the emergency switching of the valve arrangement (10) into the closed state counteracts a further adjustment of the flap (2), in particular blocks a further adjustment of the flap (2). [12] Valve arrangement according to one of claims 10 or 11, characterized by , that the gas pressure element (4) preloads the flap (2), in particular in its opening direction, and / or, that the flap arrangement (5) has on a first side of the flap (2) the actuator (3), in particular exactly one actuator (3), and on the opposite, second side of the flap (2) the gas pressure element (4), in particular exactly one gas pressure element (4). [13] Valve arrangement according to one of claims 10 to 12, characterized by, that the switching flow corresponds to a velocity of the outer edge of the flap (2) in a range between 0.5 m / s and 3.0 m / s, preferably between 0.8 m / s and 1.2 m / s, in particular of 1.0 m / s.

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