Actuator

Abstract

The invention relates to an actuator having two connection points (3, 8) and consisting of an electric drive (1) with a rod (2) which can be extended and retracted, further consisting of a pyrotechnic drive (13) having an extendable piston (14). The two drives (1, 13) are mechanically connected in series in that the pyrotechnic drive (13) is fastened to the rod (2) of the electric drive (1). It is therefore sufficient to mount a single actuator in order both to electrically open and close the engine hood and to raise same in the event of an accident involving a pedestrian. Moreover, conventional electric drives can be used.

Description

ACTUATOR Technical area

[0001] The present invention relates to an actuator having two connection points and consisting of an electric drive with an extendable and retractable rod and a pyrotechnic drive with an extendable piston. State of the art

[0002] In higher-end vehicles, gas springs are used to assist the opening of hoods and tailgates. While opening assistance declined in the past – more and more manufacturers relied on support rods because the hood only rarely needed to be opened – the advent of electromobility has brought renewed interest in this topic. The reason for this is that sporty vehicles with a long front end, or SUVs, have a storage compartment under the hood known by the portmanteau term "frunk," a combination of the words front and trunk. This front trunk is much more common in electric cars since the combustion engine is no longer present. The front trunk is naturally subject to more frequent use than the hood of a conventional vehicle; in sports cars with mid- or rear-engined vehicles, the frunk is even the only trunk.For convenience, an electric drive is often used instead of the gas spring, which allows opening and closing at the touch of a button.

[0003] At the same time, the regulations for VRUs, i.e. vulnerable road users, especially pedestrians, in Japan and China place increased demands on the protection of this group of people, which can be more easily met by raising the hood in the event of an accident.

[0004] DE102022121058B provides two actuators for the two applications: a linear actuator designed as a spindle drive and a pyrotechnic actuator, which are connected to the hood (vehicle lid) via a joint arrangement. A mechanical locking element is provided that can be released when the pyrotechnic actuator is activated to move the hood into the pedestrian protection position. This allows the hood to be moved into the pedestrian protection position without being influenced by the first actuator.

[0005] WOWO 2021 / 259682A shows a complex joint arrangement for using two actuators to open and close the hood, respectively. The device is designed so that the first actuator does not interfere with the second actuator when the second actuator is activated.

[0006] An actuator of the type mentioned above is known from DE102020131792B. According to this document, an electric motor drives a gear that meshes with another gear. This other gear drives a spindle, which can extend and retract a rotationally fixed hollow rod, thus creating a spindle drive. Furthermore, a pyrotechnic drive with a piston is provided, which can quickly extend the gear, including the spindle and hollow rod, thereby automatically releasing the connection with the motor gear. This actuator is intended for adjusting a spoiler. By combining both drives in one actuator, only one actuator needs to be attached at two points, which already results in a significant reduction in assembly costs. Another advantage is that no complicated joint arrangement is required, which is provided for in the previously mentioned documents, so that the two drives do not interfere with each other.The disadvantage of this solution, however, is that no conventional electric drive, i.e. in this case no conventional spindle motor, can be used. Description of the invention

[0007] The aim of the present invention is to find a more economical way to raise the hood for pedestrian protection and to open the hood to access the front trunk. Thus, it should be possible to economically perform both a very sudden movement, at least once, and a repeatable slow movement.

[0008] This is solved by an actuator of the type mentioned above in that the two drives are mechanically connected in series.

[0009] The series connection can be realized in three different ways: by attaching the pyrotechnic actuator to the rod of the electric actuator; or by attaching the electric actuator to the piston of the pyrotechnic actuator or forming the piston of the pyrotechnic actuator; or finally, by accommodating the pyrotechnic actuator and the electric actuator in an actuator housing, with the pyrotechnic actuator having one of the two connection points and the electric actuator having the other connection point, and the extension movement of the electric actuator being opposite to the extension movement of the pyrotechnic actuator.

[0010] With the actuator according to the invention, the pedestrian protection joint can be moved by the force of the pyrotechnic drive, meaning the hood can be raised in the area of ​​the hinges by the pyrotechnic drive as usual when the hood lock is locked. If the hood lock is unlocked, the electric drive can pivot the hood around the hinge, i.e., open it. The mechanical series connection makes it possible to use conventional electric drives, resulting in a significant cost reduction.

[0011] It is advisable for the angle between the axis of the pyrotechnic actuator and the longitudinal axis of the electric actuator to be a maximum of 30°; preferably, the axes are essentially parallel. This largely avoids bending forces.

[0012] In an advantageous embodiment, the pyrotechnic drive is mounted in the longitudinal axis of the electric drive. This arrangement has the advantage that both drives have the same line of action. Naturally, with the second type of series connection (the electric drive is attached to the piston of the pyrotechnic drive or forms the piston of the pyrotechnic drive), the exit point of the cable of the motor control of the electric drive must be laid towards the end of any spindle rod. The drive unit consisting of electric drive and pyrotechnic drive is mounted on one of its two sides, i.e. on the igniter side or the piston rod side, preferably by means of a quiver so that even small tensile movements can be accommodated.

[0013] As an alternative to positioning the pyrotechnic drive in the longitudinal axis of the electric drive, it is also possible to position the pyrotechnic drive offset from the electric drive. This allows the overall length of the actuator to be reduced. This is particularly useful with the third type of series connection (both drives in one housing with opposing extension movements). A simple design uses an actuator housing that has a hole on one side to accommodate the electric drive and, offset from this, a hole on the opposite side to accommodate the pyrotechnic drive. The holes either have a bottom in the form of a blind hole, or the drives have a step in their external geometry to prevent slipping through the hole. Openings are provided in the respective bottoms for the cables to be routed.Such an actuator housing can also be an integral part of one of the housings of the pyrotechnic or electric drive.

[0014] According to a preferred embodiment, it is provided that the electric drive is an electrically driven spindle drive, wherein the thread of the spindle preferably has a pitch of 1:5 to 1:20.

[0015] It can be provided that a slip clutch is provided between the motor and the spindle shaft, or that a spindle nut is designed as a force-dependent failure element between the motor and the spindle shaft, preferably with at least one predetermined breaking point. The activation force for the slip clutch or the failure force of the spindle nut in the longitudinal direction of the spindle shaft is preferably in the range between 1 and 5 kN. This means that the connecting piece (for example, a slip clutch or a spindle nut) between the thread of the spindle axis and the extendable part of the electric drive can be separated under the application of force.

[0016] If the drive is only subjected to pressure or if any pulling movements do not exceed the guide lengths of the electric drive or pyrotechnic drive, this design is already sufficient for a functioning system; otherwise, functions according to further sub-claims are helpful.

[0017] In order to be able to absorb higher tensile forces, a further embodiment provides for the pyrotechnic drive to be locked during normal operation, and the locking mechanism, which is preferably designed as a latch or a shearing element, can be released when the pyrotechnic drive is triggered, preferably by means of gas pressure. This, together with a connection between the two drives, also enables the absorption of tensile forces. The shearing element can be designed in the form of a circumferential step, which, with appropriate dimensions, is separated when the pyrotechnic is triggered. In the opposite direction (i.e. when compressive forces are applied), a piston for the pyrotechnic drive can be supported on a propellant casing or an ignition unit. If a latch is used, this can fix a drive part of the pyrotechnic drive to the electric drive.The latch can be released, for example, by a piston or by gas pressure when the pyrotechnic charge is triggered.

[0018] It is particularly advantageous if the locking mechanism can be restored after a triggering. Accordingly, it is possible to reduce the number of parts required for repair after a pyrotechnic triggering.

[0019] In the embodiments mentioned here, the power flow when the electric drive is extended or retracted occurs via the fixed pyrotechnic drive. This allows the transmission of both tensile and compressive forces.

[0020] In the examples shown so far, the movement of the pyrotechnic drive when triggered increases the possible total stroke of the drive. In extreme cases, the electric drive is fully extended, and the travel of the pyrotechnic drive would be added to this. This must be taken into account when integrating it into the overall system. One option for adjusting the total stroke is to provide a stroke limiter so that the maximum achievable stroke is independent of the type of drive. The stroke limiter is preferably implemented by a mechanical travel limiter, preferably implemented by a sleeve tube and a stop on the actuator. This means that a defined end position can be controlled electrically or pyrotechnically from any position of the electric drive. Some exemplary embodiments are presented below. This design is particularly suitable for weak hood joints, such as gooseneck joints.

[0021] In a simple design, the total stroke is limited by means of a travel limiter, for example a tube that, together with a bead on the drive unit, limits the travel.

[0022] In a further embodiment, the electric drive can be pushed back by triggering the pyrotechnic drive. This is particularly advantageous in a design with a spindle drive with a high pitch, as this reduces the force required to push back. On the other hand, in a design in which the spindle is separated from the motor, the force required to push back is also drastically reduced. Short description of the drawings

[0023] The present invention is explained in more detail with reference to the accompanying drawings. Fig. 1a shows a linear arrangement of electric drive and pyrotechnic drive with separate housings in the retracted state for pressurization. The actuator is designed so that the pyrotechnic drive drives its own piston; Fig. 1b shows the same arrangement with the electric drive extended; Fig. 1c shows the same arrangement with the electric drive and the pyrotechnic drive extended. Fig. 2a shows a linear arrangement of electric drive and pyrotechnic drive in a common actuator housing in the retracted state for pressurization; Fig. 2b shows the same arrangement with the electric drive extended; Fig. 2c shows the same arrangement with the electric drive and the pyrotechnic drive extended. Fig.Fig. 3a shows a parallel arrangement of the electric drive and pyrotechnic drive in the retracted state for pressurisation; Fig. 3b shows the same arrangement with the electric drive extended; Fig. 3c shows the same arrangement with the electric drive and the pyrotechnic drive extended. Fig. 4a shows a parallel arrangement of the electric drive and the pyrotechnic drive in the retracted state for pressurisation and tensile loading; Fig. 4b shows the same arrangement with the electric drive extended; Fig. 4c shows the same arrangement with the electric drive and the pyrotechnic drive extended. Fig. 5a shows a parallel arrangement of the electric drive and the pyrotechnic drive with a lock in the retracted state for pressurisation and tensile loading. In Fig. 5a, the lock locks the piston of the pyrotechnic drive; Fig. 5b shows the same arrangement with the pyrotechnic piston unlocked; Fig.Fig. 5c shows the same arrangement with the pyrotechnic piston unlocked and the pyrotechnic actuator extended. Fig. 6a shows a linear arrangement of the electric actuator and pyrotechnic actuator in a common actuator housing in the retracted state for push and pull loading with the electric actuator collapsing in the installed position; Fig. 6b shows the same arrangement with the electric actuator extended; Fig. 6c shows the same arrangement with the electric actuator extended and the pyrotechnic actuator extended (the pyrotechnic actuator is fully extended and the electric actuator pushed back). Fig. 7a shows a linear arrangement with the electric actuator and pyrotechnic actuator with stroke limitation by a cladding tube in the retracted state in the installed position; Fig. 7b shows the same arrangement with the electric actuator extended; Fig.Figure 7c shows the same arrangement with the electric drive partially extended and the pyrotechnic drive fully extended. Way(s) of carrying out the invention

[0024] Fig. 1a shows the linear arrangement of the electric actuator 1 and the pyrotechnic actuator 13, with separate housings for the two actuators 1, 13 in the retracted state for pressurization. The electric actuator 1 controls the position of the rod 2. The actuator is designed so that the pyrotechnic actuator 13 drives its own piston 14. The actuator can be attached to the connection points 3, 8, with the electric actuator 1 and the pyrotechnic actuator 13 located between them. The pyrotechnic actuator 13 is attached to the rod 2 and actuates the piston 14.

[0025] Fig. 1b shows the same arrangement with the electric drive 1 extended. The rod 2 was extended, thus moving the pyrotechnic drive 13 along with the piston 14 and the connection point 3. Fig. 1c shows the same arrangement with the electric drive 1 and the pyrotechnic drive 13 extended. Thus, the piston 14 and thus also the connection point 3 were also moved further.

[0026] Fig. 2a schematically shows the linear arrangement of the electric drive and pyrotechnic drive in a common actuator housing 4 in the retracted state for pressurization. The electric drive 1 with the movable rod 2 and the first connection point 3 is slidably accommodated in the actuator housing 4 and replaces the conventionally used piston of a pyrotechnic actuator. The stops 5 and 6 limit the possible movement of the electric drive 1 in the actuator housing 4. The actuator housing 4 also contains a pyrotechnic charge 7 with electrical ignition, which can be ignited by applying a current pulse to the cable 9. At the igniter-side end of the actuator housing 4 there is another connection point 8. The position of the movable rod 2 of the electric drive 1 (in this case designed as a spindle drive) can be controlled via the cable 10.In the simplest case, control is via the voltage supply of the motor in the electric drive 1; the polarity determines the direction, and the voltage determines the speed of movement. Of course, all other control options are also applicable. The electric drive 1 is not fixed, or is only slightly fixed, in the actuator housing 4. "Slightly fixed" here means a fixing force of less than 500 N; this is helpful for keeping the electric drive 1 in a secure position during installation. This arrangement is advantageous for systems that only require compressive forces for the drive. Tensile forces can only be absorbed by the stop 6 after the electric drive 1 has been extended.

[0027] Fig. 2b schematically shows the arrangement from Fig. 2a with the rod 2 of the electric drive 1 extended. This is the maximum achievable working position during electric operation. Any necessary retraction of the electric drive 1 in the actuator housing 4 is achieved by external forces, such as the weight of the engine hood or a spring preload in the adjustment kinematics.

[0028] Fig. 2c schematically shows the arrangement from Fig. 2a with the extended rod 2 of the electric drive 1 and the triggered pyrotechnic charge 7. The triggering of the pyrotechnic charge 7 is possible in any position of the electric drive 1, resulting in different overall lengths in the triggered state. Therefore, it may be advantageous to limit the overall stroke in the adjustment kinematics of the hood. This is shown in another exemplary embodiment. This limitation either limits the movement of the electric drive 1 in the actuator housing 4, or pushes the electric drive back when the pyrotechnic charge 7 is triggered.

[0029] Fig. 3a schematically shows the parallel arrangement of electric drive 1 and pyrotechnic drive 13 in the retracted state for pressurization. The electric drive 1 with the movable rod 2 and a first connection point 3 is slidably housed in an actuator housing 4'. Furthermore, a pyrotechnic drive 13 with a movable piston 14 and a second connection point 8 is present in the actuator housing 4'. Both drives 1, 13 are inserted into the actuator housing 4', and at least one drive is fixed only slightly. "Slightly" here means a fixing force of less than 500 N, which is helpful for keeping the drive 1 or 13 in a secure position during assembly.

[0030] This arrangement is advantageous for systems where only compressive forces are required for propulsion. Tensile forces can only be absorbed up to the maximum fixing force of the only slightly fixed drives 1 or 13. In an alternative design, the actuator housing 4' is part of the electric drive 1 and / or the pyrotechnic drive 13.

[0031] The pyrotechnic drive 13 can be installed as shown, ie with the igniter-side end in the actuator housing 4', or conversely with the igniter-side end to the second connection point 8.

[0032] The installation of the pyrotechnic drive 13 at the end of the electric drive 1 is only an example; for many applications it is more advantageous in terms of installation space to move the second connection point 8 towards the first connection point 3, i.e. to move the pyrotechnic drive towards the end of the rod 2 in order to save installation length or distance between the connections, usually ball studs, or to be able to flexibly adapt the starting length to the requirements of the hinge arrangement of the bonnet, independent of the electric stroke.

[0033] Fig. 3b shows schematically the same arrangement from Fig. 3a with the electric drive 1 extended. Fig. 3c shows schematically the same arrangement from Fig. 3a with the electric drive 1 and the pyrotechnic drive 13 extended.

[0034] Fig. 4a schematically shows an arrangement similar to Fig. 3a, with the difference that the arrangement shown in Fig. 4a is also suitable for absorbing tensile forces. The connection between the two drives 1, 13 is shown as a positive connection at connection points 15 and 16. The piston 14 of the pyrotechnic drive 13 has a safety device for securing the initial position, for example, a shear element, which is overcome when the pyrotechnic charge 7 is triggered.

[0035] Fig. 4b shows schematically the arrangement from Fig. 4a in the extended state of the electric drive 1. By retracting the electric drive 1, the starting position according to Fig. 4a can be reached again from the state as shown in Fig. 4b.

[0036] Fig. 4c shows schematically the arrangement from Fig. 4a in the extended state of the electric drive 1 and the extended state of the pyrotechnic drive 13.

[0037] Fig. 5a shows the parallel arrangement of the electric drive 1 and the pyrotechnic drive 13 with a locking mechanism in the retracted state for compressive and tensile loading. A locking mechanism is provided for the piston 14 of the pyrotechnic drive 13, which locks the piston 14 in Fig. 5a. The locking is achieved by a locking hook 31 engaging the piston 14 and is reversible. Thus, in this embodiment, it can be ensured that the piston 14 cannot be extended in the locked state. Fig. 5b shows the same arrangement with the unlocked piston 14. Fig. 5c shows the same arrangement with the unlocked piston 14 and the actuated pyrotechnic drive 13, thus extending the piston 14.

[0038] Fig. 6a shows a schematic of a linear arrangement of electric drive 1 and pyrotechnic drive 13 in an actuator housing 4 in the retracted state for compressive and tensile loading with collapsing electric drive 1 in the installed position. The structure essentially corresponds to Fig. 2a, i.e. the electric drive 1 represents the piston of the pyrotechnic drive 13. In contrast to Fig. 2a, the electric drive 1 in the actuator housing 4 is also secured against withdrawal by the detachable connection 19. In addition, the electric drive 1 is designed such that the rod 2 can be pushed back when it encounters resistance, represented here by the external travel limits 17 and 18. The retractability can be achieved, for example, by a correspondingly steep design of a spindle in the case of a spindle drive.

[0039] Fig. 6b schematically shows the same arrangement as Fig. 6a, with the electric drive 1 extended until it reaches the travel limits 17, 18. This may—but does not have to—be the end of the travel range of the electric drive 1.

[0040] Fig. 6c schematically shows the same arrangement as in Fig. 6a, with the pyrotechnic drive 13 extended and the electric drive 1 retracted according to the travel limits 17, 18. In a particularly preferred embodiment, the travel limits 17, 18 are reached by the sole extension of the pyrotechnic drive 13, while the electric drive 1 is retracted regardless of its state.

[0041] Fig. 7a shows a linear arrangement with an electric drive 1 and a pyrotechnic drive with stroke limitation by a sheath tube 21 in the retracted state in the installed position. The structure is similar to that in Fig. 6a, ie, the electric drive 1 forms the piston for the pyrotechnic drive, but the total travel is additionally limited in the actuator.

[0042] The electric drive 1 is connected to the actuator housing 4 by a detachable connection 19. The end 20 of the rod 2 (visible only in Figs. 7b and 7c) of the electric drive 1 is connected to a stop 22 via a sleeve 21. The actuator housing 4 also has a stop 23, which creates a travel limit for both drives.

[0043] Fig. 7b shows the same arrangement as Fig. 7a with the electric drive 1 extended. The electric drive 1 is extended as far as possible by the stops 22 and 23. By retracting the electric drive 1, the initial position shown in Fig. 7a can be reached again from the state shown in Fig. 7b, since the electric drive 1 is fixed in the actuator housing 4 by the detachable connection 19.

[0044] Fig. 7c shows the same arrangement as Fig. 7a with the electric drive and pyrotechnic drive partially extended. This condition occurs when the electric drive 1 is not fully extended and the pyrotechnic charge 7 is ignited. Under the pressure of the pyrotechnic charge, the electric drive 1 overcomes the detachable connection 19 and is propelled forward until the stops 22 and 23 are activated.

[0045] The travel limit is useful because, in the event of a misfire when the hood is already open by the electric drive, the pyrotechnic drive does not damage the hood's opening mechanism. The stroke limit in the actuator can significantly reduce the effort required for the kinematics of opening the hood.

[0046] List of reference symbols 1 Electric drive 2 Movable rod of the electric drive 3 First connection point of the actuator 4, 4' Actuator housing 5 First stop for the electric drive 6 Second stop for the electric drive 7 Pyrotechnic charge with electrical ignition 8 Second connection point of the actuator 9 Cable to the pyrotechnic charge 10 Cable to the electric drive 13 Pyrotechnic drive 14 Piston of the pyrotechnic drive 15 Connection between pyrotechnic drive and actuator housing 16 Connection between electric drive and actuator housing 17, 18 Travel limits 19 Detachable stop for the electric drive 20 End of the movable rod of the electric drive 21 Sheath tube 22 Stop on the sheath tube 23 Stop on the actuator housing 31 Locking hook 32 Release lever 34 Pivot point

Claims

Actuator having two connection points (3, 8) and consisting of an electric drive (1) with an extendable and retractable rod (2) and a pyrotechnic drive (13) with an extendable piston (14), characterized in that the two drives (1, 13) are mechanically connected in series. Actuator according to claim 1, characterized in that the series connection is realized in that the pyrotechnic drive (13) is fastened to the rod (2) of the electric drive (1). Actuator according to claim 1, characterized in that the series connection is realized in that the electric drive (1) is attached to the piston (14) of the pyrotechnic drive (13) or forms the piston of the pyrotechnic drive (13). Actuator according to claim 1, characterized in that the series connection is realized in that the pyrotechnic drive (13) and the electric drive (14) are accommodated in an actuator housing (4'), wherein the pyrotechnic drive (13) has one of the two connection points (8) and the electric drive (1) has the other connection point (3), and the extension movement of the electric drive (1) is opposite to the extension movement of the pyrotechnic drive (13). Actuator according to one of claims 1 to 4, characterized in that the angle between the axis of the pyrotechnic drive (13) and the longitudinal axis of the electric drive (1) is a maximum of 30°. Actuator according to claim 5, characterized in that the axis of the pyrotechnic drive (13) and the longitudinal axis of the electric drive (1) are substantially parallel. Actuator according to claim 6, characterized in that the pyrotechnic drive (13) is mounted in the longitudinal axis of the electric drive (1). Actuator according to claim 4, characterized in that the pyrotechnic drive (13) is positioned offset in axis relative to the electric drive (1). Actuator according to one of claims 1 to 8, characterized in that the electric drive (1) is an electrically driven spindle drive. Actuator according to claim 9, characterized in that the thread of the spindle has a pitch of 1:5 to 1:

20. Actuator according to claim 9 or 10, characterized in that a slip clutch is provided between the motor and the spindle shaft or a spindle nut is designed as a force-dependent failure element between the motor and the spindle shaft, preferably with at least one predetermined breaking point, wherein the activation force for the slip clutch or the failure force of the spindle nut in the longitudinal direction of the spindle shaft is preferably in the range between 1 and 5 kN. Actuator according to one of claims 1 to 11, characterized in that the pyrotechnic drive (13) is locked during normal operation, and the locking mechanism, which is preferably designed as a latch or as a shearing element, can be released upon triggering of the pyrotechnic drive (13), preferably by means of gas pressure. Actuator according to claim 12, characterized in that the locking can be restored after triggering. Actuator according to one of claims 1 to 13, characterized in that a stroke limitation is provided so that the maximum achievable stroke is independent of the type of drive, and that the stroke limitation is preferably effected by a mechanical travel limitation, and this is preferably realized by a sleeve tube (21) and a stop on the actuator (23). Actuator according to one of claims 1 to 14, characterized in that the electric drive (1) can be pushed back by triggering the pyrotechnic drive (13).

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