Driving device

A driving device for pivoting a flap with respect to a body includes a cylindrical pressure tube having a closed first end and a second end with a seal, a piston dividing the pressure tube into a first working chamber and a second working chamber, a piston rod extending through the first working chamber and the seal, a gas under pressure in the first and second working chambers, and a sealing and guiding cap fixed to the second end of the pressure tube. An outer tube has a closed first end and an open second end which receives the pressure tube in a telescoping manner, thereby forming a third working chamber between the second end of the pressure tube and the first end of the outer tube, wherein a fluid can be conveyed into and out of the third working chamber.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention is directed to a driving device, particularly for a hatch in a vehicle.

2. Description of the Related Art

There is a wide variety of known driving devices for moving vehicle hatches. For example, U.S. Pat. No. 6,600,285 shows a driving device with a Bowden cable system and a direct drive for opening and closing a vehicle hatch in which an electric motor with a gear unit and clutch is used.

Further, US2007/0062119 discloses a driving device in which a spindle drive brings about automatic closing and opening by means of a motor with a gear unit and a clutch.

Drives of the kind mentioned above are very complicated with respect to construction and accordingly entail relatively high manufacturing costs.

SUMMARY OF THE INVENTION

Therefore, it is an object of the invention to provide a driving device for hatches which is constructed in a simple manner, is easy to assemble and is economical to produce.

According to the invention, in that the driving device includes a gas spring having a cylindrical pressure tube which is closed at a first end and in which a piston is arranged so as to be displaceable. The piston divides the pressure tube into a first work chamber and a second work chamber and has a piston rod which penetrates the first work chamber and is guided out at a second end of the pressure tube, with a gas filling of the first work chamber and second work chamber which is under pressure and through which the piston is acted upon by a push-out force. The piston rod passes through a sealing and guiding cap with sealing ring arranged at the second end of the pressure tube and an outer tube which is closed at a first end by a bottom and in which the gas spring is arranged in a telescoping manner, wherein a fluid can be conveyed into or out of the interior of the outer tube.

In a further development, a pressure connection device by which the fluid can be conveyed into or out of the outer tube is arranged at the bottom.

Alternatively, a threaded pin is formed at the end of the piston rod located opposite to the piston, an axial bore hole extends through the threaded pin and opens into a radial bore hole communicating with the interior of the outer tube, the fluid can be conveyed into or out of the outer tube through this radial bore hole.

In a further development, the threaded pin is guided out of the outer tube through an opening in the bottom.

To fasten the driving device to a base part and to a structural component part which is swivelable relative to the base part, a first connection element is arranged at the first end of the pressure tube and a second connection element is arranged on the threaded pin outside the outer tube.

A sealing element is advantageously arranged between the second connection element and the bottom of the outer tube so that the fluid cannot flow out of the pressure system in an uncontrolled manner.

The sealing element is constructed as an0-ring seal which is arranged in an inset in the second connection element.

Alternatively, the sealing element is constructed as an annular disk seal, in which case the widened diameter can be omitted so that a more economical production of the connection element is possible.

To connect the second connection element to the piston rod, a threaded pin is formed at the end of the piston rod located opposite to the piston. Alternatively, an adapter piece with an internal thread may be screwed on the threaded pin.

Owing to the use of the adapter piece, a standard, mass-produced piston rod may be used and the adapter piece can be produced independent from the production of the piston rod.

In a further development, the adapter piece has a threaded pin at the end located axially opposite to the internal thread, an axial bore hole extends through the threaded pin and opens into a radial bore hole communicating with the interior of the outer tube, the fluid can be conveyed into or out of the outer tube through this radial bore hole.

The threaded pin is guided out of the outer tube through the opening in the bottom, and the second connection element is screwed onto the threaded pin of the piston rod or onto the threaded pin of the adapter piece with a first receiving chamber which is formed in a fastening shaft and has, at least partially, an internal thread.

In an advantageous manner, the first receiving chamber is connected by an overflow channel to a second receiving chamber having an area shaped like a spherical segment.

The second receiving chamber has a first groove for receiving a locking ring by which a head of a ball-head pin is held in the second receiving chamber so as to be swivel able.

Further, the second receiving chamber has a second groove for receiving a sealing element to provide a preferably gastight connection between the second connection element and the head of the ball-head pin.

In a further development, a through-hole extends through the ball-head pin.

In order to connect the ball-head pin to a pressure generating unit, a pressure connection is provided at the side of the ball-head pin located opposite to the head.

In another embodiment form of the invention, the piston comprises a switching valve to block the gas spring.

In another construction, the switching valve has a valve pin.

The valve pin comprises at one end a small piston which is arranged in a chamber connected to the axial bore hole in the piston rod.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

FIG. 1is a schematic view of a motor vehicle with a body as a base part1and a movable part which closes or opens an opening2in the base part1and which is constructed as a hatchback, hereinafter referred to as a hatch3. The hatch3can also be a front hood or engine hood, a vehicle door or a corresponding application.

The hatch3is mounted in a horizontal swiveling axis4extending transverse to the vehicle. A first driving device5is arranged at one side of the hatch3and a second driving device6is arranged at the opposite side of the hatch3. It is possible for one of the two driving devices5and6, or both, to be formed by the driving device described in the following. If only one of the two driving devices5or6comprises the driving device according to the invention, the other driving device is preferably formed by a commercially available gas spring which counterbalances a substantial portion of the weight force of the hatch.

The embodiment form of the driving device5shown inFIG. 2includes a gas spring7with a center longitudinal axis A, a pressure tube8with a closed first end9and an open second end10located opposite to the closed end9. A piston rod11is guided out of the pressure tube8through a sealing and guiding package12in the second end10in coaxial arrangement relative to the pressure tube8and to the center longitudinal axis A. A first connection element13is arranged at the closed end9of the pressure tube8. The connection element13is preferably formed as a ball socket. The connection element13can also be constructed as a knuckle eye or the like.

A piston14divides the pressure tube8into a first work chamber15, through which the piston rod11extends, and a second work chamber16. To allow the gas which is under pressure in the pressure tube8to flow from one work chamber to the other, overflow devices already known for gas springs can be provided. For example, a groove17extending in axial direction can be provided in the pressure tube8and/or a piston ring18under which flow can occur. A threaded pin19with a smaller outer diameter is formed at the end of the piston rod11located outside the pressure tube8.

The driving device5further includes an outer tube20with a first end22which is closed by a bottom21and with an open second end23located opposite to the first end22. The gas spring7is inserted into the outer tube20by its first end10, and the threaded pin19of the piston rod11is guided through an opening24which is arranged in the bottom21of the outer tube20coaxial to the center longitudinal axis A. In doing so, the piston rod11contacts the bottom21in the interior of the outer tube20by a shoulder25formed by the transition from the piston rod11to the threaded pin19having a smaller outer diameter.

Further, a pressure connection device26which is connected to a pressure generating unit, not shown, is arranged off center in the bottom21. A fluid is conveyed into or out of a third working chamber inside the outer tube20via the pressure connection device26. A sealing and guiding cap27is arranged over the second end10of the gas spring7so that the fluid conveyed into the interior of the outer tube20cannot escape from the second end23. The sealing and guiding cap27fits on the second end10of pressure tube8with a press fit or has at least one projection28which engages in a recess29formed in the pressure tube8. The recess29can be formed as a circumferential groove or as one or more discrete recesses.

The sealing and guiding cap27has a circumferential channel30, and a sealing ring31which seals against the outer tube20inserted into the channel30. A second connection element32with a fastening shaft33having a first receiving chamber34with an internal thread35is screwed onto the threaded pin19projecting through the opening24. An inset36in which an0-ring-shaped sealing element37is inserted is formed at the open end of the first receiving chamber34facing the bottom21. Further, the second connection element32has a second receiving chamber38which has a spherical socket portion39that receives a ball head40of a ball-head pin41so as to be pivotably movable. The head40has a flattened portion in the socket portion39and is held in the socket portion39by means of a locking ring42arranged in a circumferential groove43in the second receiving chamber38.

The pressure in the gas spring7is selected so that the push-out force acting on the hatch3is somewhat less than the weight force of the hatch3acting in the closing direction. When a fluid is permitted to flow into the outer tube20via the pressure connection device26, the sealing and guiding cap27is moved toward the second end23of the outer tube20and the second end10of the pressure tube8is moved toward the piston14together with the sealing and guiding device12. The position of the piston14, relative to second end23, does not change. The gas spring7accordingly moves out. Since most of the weight force of the hatch3is counterbalanced by the gas spring, only a very small pressure is needed in the outer tube20to move the hatch3into a completely open or partially open position. The pressure can be approximately 10 bar or less. A pressure of about 4 bar is preferable.

When the pressure in the outer tube20is reduced again in order to close the hatch3, the sealing and guiding cap27, together with the second end10of the pressure tube8, is moved in direction of the bottom21by the weight force of the hatch3. The gas spring accordingly moves in.

FIG. 3shows a second embodiment form of the invention. In this case, the pressure connection device26in the bottom21of the outer tube shown inFIG. 2is omitted. Instead, the fluid is conveyed into or out of the interior of the outer tube20via an axial bore hole44formed coaxial to the center longitudinal axis A. The axial bore hole44extends from the end of the piston rod11located outside of the pressure tube8through the threaded pin19and opens into a radial bore hole45communicating with the interior of the outer tube20. Further, the sealing element37is formed as a sealing disk so that the widened diameter36shown inFIG. 2can be dispensed with.

In order to convey the fluid through the axial bore hole38and radial bore hole39in a simple manner without a hose always having to be moved along with it, the second connection element32has an overflow channel47which connects the first receiving chamber34to the second receiving chamber38. The ball-head pin41has a through-hole48which extends from the flattened portion in the ball head40substantially coaxial to the center longitudinal axis B of the ball-head pin41to the oppositely located end49of the ball-head pin41. The end49of the ball-head pin is preferably connected to the base part1and to a pressure connection device which is not shown in this case.

In order to prevent the fluid from escaping from the second receiving chamber38in an uncontrolled manner, a circumferentially extending groove50is arranged in the second receiving chamber38at half the height of the equator of the head40and an O-ring sealing element51is seated in this groove50.

FIG. 4shows a third embodiment form of the driving device5according to the invention. An adapter piece52with an internal thread53is screwed onto the threaded pin19of the piston rod11. The adapter piece52has at the side opposite to the internal thread53a threaded pin54with a smaller diameter which, in the same way as the threaded pin19described inFIG. 3, is guided through the opening24in the bottom21of the outer tube20and connected to the second connection element32so as to be sealed by the sealing element37.

The axial bore hole44is formed in the adapter piece52and extends from the end of the adapter piece52located outside of the outer tube20through the threaded pin54and opens into the radial bore hole45communicating with the interior of the outer tube20. The adapter piece52can be produced from a metal material or can be made of plastic, which further simplifies production.

Owing to the use of the adapter piece52, a standard, mass-produced piston rod11may be used. Further, the adapter piece52can be produced independent from the production of the piston rod.

FIGS. 5 and 6show a fourth embodiment form of the driving device5according to the invention.FIG. 6is a detailed view of the driving device5shown inFIG. 5.

In contrast to the other embodiment forms, no flow occurs under the piston ring18in the groove17of the piston14, and the axial bore hole44extends coaxial to the center longitudinal axis A through the same piston rod11so that a switching valve arranged in the piston14can be actuated. A threaded pin55is formed at the end of the piston rod11located in the gas spring7. A sleeve56with internal threads in both ends is screwed onto this threaded pin55. The piston14is screwed into the end opposite the piston rod11. The two internal threads of the sleeve56extend into the latter only as far as is necessary to screw the piston rod11and the piston14securely to the sleeve56. A chamber57is formed between the areas with the internal threads. A spring element58supported substantially at the end of the piston rod11is arranged in this chamber57.

A small piston59which divides the chamber57into a first partial chamber60and a second partial chamber61contacts the end of the spring element remote of the piston rod11, the spring element58being arranged in the first partial chamber60. The small piston59has a groove62on its radially circumferential outer surface, a sealing ring63being inserted into this groove62. A bore hole64with an internal thread is formed coaxial to the center longitudinal axis A, and a threaded plug65of a valve pin66is screwed into this bore hole64. The small piston59is constructed so that the fluid flowing into the axial bore hole44and the first partial chamber60cannot flow into the second partial chamber61.

For reasons of safety, a sealing ring, not shown, can be arranged at the valve pin66in such a way that it prevents fluid from flowing through between the bore hole64and the threaded plug65if this is not already provided for by the structural component parts themselves.

The valve pin66is guided coaxial to the center longitudinal axis A in a piston chamber68in the piston14so as to be sealed by means of a sealing and guiding device67. The piston chamber68is connected to the second work chamber16by a coaxial connection opening69and to the first work chamber15by at least one radial connection opening70. An annular chamber71with two annular shoulders72and73arranged at a distance from one another is formed in the area of the coaxial connection opening69. Arranged in the annular chamber71is a sealing ring74which tightly contacts the cylindrical wall of the piston chamber68by its radial circumferential outer surface. The sealing ring74is fixed axially to an annular disk75contacting the shoulder73between the annular shoulder72and the annular disk75.

The cylindrical valve pin66has end regions76and77and a central area78of reduced diameter therebetween.

A radial widening formed by a disk79at the end of the valve pin66facing the second work chamber16forms a stop which limits the sliding-in movement of the valve pin66into the piston14.

In order to open the hatch3, pressure must be applied to the small piston59by fluid via the axial bore hole44. In so doing, the small piston59is moved axially in direction of the second work chamber16, and the end area76of the valve pin66is lifted from the sealing ring74. The fluid contained in the gas spring7can flow from the first work chamber15into the second work chamber16via the radial connection opening70and the coaxial connection opening69when a fluid is conveyed into the outer tube via the pressure connection device26.

When the pressure of the fluid in the axial bore hole decreases again, the small piston59moves back into its initial position again and the end region76of the valve pin66tightly contacts the sealing ring74. The gas spring7is accordingly blocked and a movement of the hatch3is no longer possible.

To close the hatch3, the small piston59must be acted upon again by the fluid and the fluid must be moved out into the interior of the outer tube20.

In order to deactivate the switching valve within certain ranges, one or more grooves17, as shown inFIGS. 2 to 4, can be provided in the pressure tube8.

In all of the embodiment examples, the fluid conveyed into or out of the interior of the outer tube20can be air generated by a compressor, or a liquid medium such as hydraulic oil. This may be controlled by means of sliders or proportional valves. The speed during opening and closing can also be regulated by means of the latter. Any variations in the force of the gas spring7that may be caused by temperature fluctuations can be compensated in this system by the proportional valve with the help of a temperature gauge. Further, a spring element, for example, a helical pressure spring, supporting the push-out movement of the gas spring can also be arranged in the outer tube.

Further, a valve can be provided in the system for emergency operation so as to open in case the system pressure noticeably exceeds the operating pressure. This overpressure can occur, for example, when the hatchback3is opened or closed manually. Further, a throttle can be integrated in the system, for example, at the pressure connection device, so as to limit the throughflow quantity.

Particularly in the embodiment form shown inFIGS. 5 and 6, the groove17in the piston14can have cutouts, not shown, through which the piston ring18can deform when a defined pressure on the piston ring18is exceeded and a flow path can be opened between the inner wall of the pressure tube8and the piston14.