Actuator for an air guide element of a motor vehicle

Abstract

Actuating element for an air guide element of a motor vehicle, wherein the air guide element (2) is adjustable in its position relative to the motor vehicle (3) between a first position and a second position, wherein for adjustment the actuating element (1) is operatively connected with a kinematic (26) of the air guide element (2), and wherein the actuating element (1) has an actuating motor (4) and an actuating shaft (5) which is operatively connected with the kinematic (26), and wherein a gearbox (12) is formed between the actuating shaft (5) and the actuating motor (4), which is not self-locking, characterized in that, in order to achieve a secure positioning of the air guide element (2), the gearbox (12) is designed to be efficiency-optimized, wherein the gearbox (12) has high internal friction with a simultaneously relatively high efficiency, such that at certain load points no reverse rotation of the actuating shaft (5) is possible.and wherein the transmission (12) is a helical gear transmission.

Description

[0001] The invention relates to an actuating element for an air guiding element of a motor vehicle according to the preamble of patent claim 1.

[0002] Air deflectors for motor vehicles are well known. These air deflectors, which are preferably arranged at the rear of the vehicle, have a profile that can be adjusted relative to the vehicle body between a retracted rest position and a fully extended active position. For example, motor vehicles are known whose air deflectors, also called spoilers, can be retracted into the body and are predominantly located outside the body in their active position.

[0003] The air guiding elements are moved into their respective positions using an actuating element and a kinematic system formed between the actuating element and the air guiding element. Furthermore, the actuating element serves to securely position the air guiding element, particularly in the active position. For this purpose, the actuating elements are usually designed to be self-locking. However, the problem is that if the air guiding element is overloaded, the self-locking mechanism prevents it from retracting in accordance with the overload, and instead damages the actuating element and the kinematic system. There are many different causes of this overload, and this can be caused, for example, by people leaning on or sitting on the air guiding element.

[0004] European patent EP 2 716 529 A2 discloses an actuator for an air guide element of a motor vehicle, wherein the actuator is not self-locking. A brake in the form of a magnetic brake is designed to fix the air guide element in both an extended and a retracted position.

[0005] From the published patent application DE 10 2014 012 292 A1, an actuator for an adjustable air guiding device is known, wherein a reduction gear is designed for the mechanical transmission of an actuating force to the air guiding device, with a first worm drive coupled to an output shaft of an electric motor, the worm wheel of which can be brought into operative connection with a worm of a second worm drive, wherein the worm wheel of which is operatively connected to an adjusting shaft for the air guiding device.

[0006] It is the object of the present invention to provide an alternative actuating element for an air guide element of a motor vehicle.

[0007] The object is achieved according to the invention by an actuating element for an air guide element of a motor vehicle having the features of patent claim 1. Advantageous embodiments with expedient and non-trivial further developments of the invention are specified in the respective subclaims.

[0008] The actuating element according to the invention for an air guiding element of a motor vehicle, wherein the air guiding element is adjustable in its position relative to the motor vehicle between a first position and a second position, is operatively connected to a kinematics of the air guiding element for adjustment. The actuating element has an actuating motor and an actuating shaft which is operatively connected to the kinematics. A gear which is not self-locking is formed between the actuating shaft and the actuating motor. According to the invention, to bring about secure positioning of the air guiding element, the gear is designed to be efficiency-optimized, wherein the gear has high internal friction and, at the same time, a relatively high efficiency such that, at certain load points, no reverse rotation of the actuating shaft is possible, and wherein the gear is a helical gear.In this context, an efficiency-optimized gearbox is understood to be one that exhibits high internal friction while maintaining a relatively high efficiency, such that it prevents the control shaft from rotating backward at certain load points. Since self-locking occurs at low efficiency in a gearbox, especially a worm gear, this self-locking effect must be eliminated due to the efficiency.

[0009] The efficiency-optimized gearbox, which is characterized by a relatively high level of efficiency, serves to prevent self-locking, thus enabling reverse rotation of the actuating shaft. Furthermore, the increased efficiency of the gearbox in the efficiency-optimized gearbox is combined with an increase in internal friction within the gearbox, particularly the friction at the bearing points of the gearbox, such that secure positioning of the air guide element is possible. This means that the gearbox is not self-locking, but due to its design as an efficiency-optimized gearbox, reverse rotation of the actuating shaft is only permitted above a certain load on the air guide element, and enables secure positioning of the air guide element at permissible loads.In other words, this means that the gearbox is designed to cause the control shaft to rotate backwards when a maximum load limit is exceeded.

[0010] The maximum load limit is to be determined depending on the maximum motor cogging torque and the efficiency-optimized gearbox.

[0011] The gearbox is preferably a worm gear, which is characterized by low noise compared to other types of gearboxes.

[0012] To achieve a particularly secure positioning of the air guide element, the gearbox has an efficiency with a value greater than 0.5.

[0013] If the actuating element additionally has a brake which, in conjunction with the efficiency-optimized gear, prevents the actuating shaft from turning back up to a certain, selected load and, when this certain load is exceeded, also referred to as the maximum load limit, allows the actuating shaft to turn back and thus a retraction movement of the air guide element, the positioning of the air guide element is preferably secured.

[0014] If the actuator incorporates a brake, the maximum load limit is determined based on the maximum motor cogging torque and the braking torque of a brake, as well as the efficiency-optimized gearbox. The advantage lies in the possibility of implementing a space-optimized design of the actuator.

[0015] The brake is a mechanical brake and / or an electric brake. If the brake is a mechanical brake, it is preferably designed as a multi-disk brake or a loop band brake. One advantage of the loop band brake is its space-optimized arrangement, as it can be designed to encompass the actuating shaft, thus requiring no additional installation space. The advantage of the electric brake is precise adjustment of the braking force. The electric brake is preferably designed in the form of a direct current motor (also called a DC motor), in particular in the form of a brushless direct current motor (also called an EC motor). The brushless direct current motor is lighter than the brush-based direct current motor.A further advantage of the electric brake, when combined with the efficiency-optimized transmission and the mechanical brake, is that the mechanical brake can be designed relatively small and, up to a certain load, provides a holding force in conjunction with the efficiency-optimized transmission. Only above this certain load does the electric brake, with its electrical holding force, contribute to the holding force required to securely position the air guide element. In other words, the electric brake only needs to be activated above a certain vehicle speed. This results in an energy-optimized and compact actuator.

[0016] With the actuator designed as described above, the actuator and also the kinematics as well as the air guide element can be protected in a simple manner from damage caused by exceeding the maximum load limit.

[0017] Further advantages, features, and details of the invention will become apparent from the following description of preferred embodiments and from the drawings. The features and combinations of features mentioned above in the description, as well as the features and combinations of features mentioned below in the description of the figures and / or shown alone in the figures, can be used not only in the respective combinations specified, but also in other combinations or on their own, without departing from the scope of the invention. They show: Fig. 1 in a perspective interior view from above an adjusting element according to the prior art, Fig. 2 in a perspective interior view from above an adjusting element according to the invention, Fig. 3 in a perspective interior view from below the adjusting element according to. Fig. 2, Fig. 4 in a perspective view a brake of the actuating element according to. Fig. 2, Fig. 5 a holding force-speed diagram of the actuating element according to. Fig. 2 of an air guide element, and Fig. 6 in a perspective view a rear of a motor vehicle having the air guide element.

[0018] An actuator 1 according to the prior art for a Fig. 6 illustrated air guide element 2 of a motor vehicle 3, is according to Fig. 1. The actuating element 1 has an electrically operable actuator 4, by means of which an actuating shaft 5 is movable. The actuating shaft 5 is mounted in a housing 6 of the actuating element 1 so as to be rotatable about its longitudinal axis 7, with a first end 8 of the actuating shaft 5 and a second end 9 of the actuating shaft 5 projecting from the housing 6 and being operatively connected to the air guide element 2.

[0019] The housing 6 is divided along a longitudinal extent of the actuating element 1 into a first housing part 10 and a second housing part 11, which Fig. 3 is shown, divisible, where in Fig. 1, the second housing part 11 for the interior view of the actuator 1 from above is not shown. It should be briefly mentioned here that the terms "top" and "bottom" serve only to distinguish the views of the actuator 1. They do not indicate how the actuator 1 is installed in the motor vehicle 3.

[0020] The rotational movement of the actuating shaft 5 is brought about by means of a gear 12 having two gear stages: a first gear stage 13, which is connected to the servo motor 4, and a second gear stage 14, which is connected to the actuating shaft 5. The gear stages 13, 14 are each designed in the form of a worm gear, which is characterized in particular by low noise compared to other gear pairs and a low efficiency due to a corresponding relative arrangement of the meshing gear elements, a so-called worm and a so-called worm wheel. Thus, the first gear stage 13 is assigned a first worm 15 and a first worm wheel 16, and the second gear stage 14 is assigned a second worm 17 and a second worm wheel 18.

[0021] The servomotor 4, which is designed as an electric motor, is connected to a plug-type connector 19 for power supply, which is accommodated on the housing 6. The servomotor 4 is preferably in the form of a conventional DC motor or, more preferably, in the form of a brushless DC motor, since this is characterized by its low weight compared to the conventional DC motor.

[0022] The actuator 1 according to the prior art is designed to be self-locking. In other words, a reverse rotation of the actuator shaft 5 of the actuator 1 is not possible if the permissible maximum load is exceeded. This means that, when the air guide element 2 is extended, excessive loading on the actuator shaft 5 can lead to failure of parts of the actuator 1, in particular the gear stages 13, 14, since reverse rotation is not provided. Excessive loading is understood to mean exceeding a maximum load limit of the actuator 1, for example, due to a person leaning against the air guide element 2.

[0023] To avoid such a failure, the adjusting element 1 according to the invention is designed, which according to the Fig. 2 and Fig. 3. The actuating element 1 according to the invention is not self-locking in comparison to the actuating element 1 of the prior art.

[0024] In Fig. 3 shows the adjusting element 1 without the first housing part 10, this being an internal view of the adjusting element 1 according to the invention from below, thus from the direction of view of the Fig. 2 opposite direction of view, is permitted. Clearly visible in Fig. 3 the first worm wheel 16 and the second worm 17, which are connected to each other in a rotationally fixed manner by means of a shaft 20.

[0025] The actuating element 1 according to the invention is fundamentally designed for the secure positioning of the air guide element 2 up to a maximum force acting on the actuating element 1, which can be referred to as the maximum load limit. To extend the air guide element 1, the actuating shaft 5 has a first rotation, whereas to retract it has a second rotation, the reverse rotation, directed opposite to the first rotation about its longitudinal axis 7.

[0026] If the maximum force is exceeded due to an overload, the actuating shaft 5 performs a second rotation due to its non-self-locking nature, and the actuating element 1 is then in a retracted state. The actuating element 1 can be retracted to its end position, but it can also be retracted to a load point below the overload and the corresponding position. This can be adjusted using sensors and control elements that communicate electronically and / or mechanically with the actuating element 1.

[0027] A securing device for the air guiding element 2, which is necessary for the secure positioning of the air guiding element 2 due to the non-self-locking of the actuating element 1, is brought about by means of an efficiency-optimized gear 12, preferably in the form of a helical gear, which comprises the two gear stages 13, 14, wherein these gear stages have an increased efficiency.

[0028] The increase in frictional resistance of gear stages 13, 14 can be achieved by increasing the friction between the worms 15, 17 and the corresponding worm gears 16, 18. For example, the tooth pairs of worm 15, 17 and worm gear 16, 18 could have increased flank contact of the individual teeth. And / or a surface of the worms 15, 17 and / or the corresponding worm gears 16, 18 could have increased surface roughness to increase friction. Various measures for increasing friction are conceivable here.

[0029] Furthermore, the efficiency-optimized gearbox 12 exhibits higher friction in its gearbox bearings 25 than in the prior art. Due to the increased friction, a higher force, or rather, a higher load, must be exerted on the air guide element 2 so that it can be retracted from its currently extended position.

[0030] In the present embodiment, the first screw 15 is designed without a through-opening and is connected in a rotationally fixed manner to an output shaft 24 of the servo motor 4 by means of a compression fitting.

[0031] An additional securing device for the air guide element 2 is provided by means of a particularly mechanical brake 21, which is preferably designed as a multi-disk brake or a loop-band brake. In the present embodiment, the brake 21 is designed as a loop-band brake, see. Fig. 4. The brake 21 has a braking force required to ensure the secure positioning of the air guide element 2.

[0032] In Fig.Figure 5 shows a holding force-speed diagram of the actuating element 1 according to the invention, showing the required holding force F plotted against a speed v of the motor vehicle 3, which is required to secure the various positions of the air guide element 2. The holding force F corresponds to a force exerted by the actuating element 1 and required to hold the air guide element 2 in its current position at a corresponding speed.

[0033] The speed v1 is assigned to the position of the air guide element 2, from which the air guide element 2 is extended upon an increase in speed, provided it has been retracted to this speed. Thus, the speed v1 is referred to as the speed at the time of extension. Therefore, an additional force is required to extend the air guide element 2, causing the holding force F to change abruptly.

[0034] In the present embodiment, the holding force F is composed of a mechanical holding force 22 and an electrical holding force 23. The mechanical holding force 22 itself is composed of a resistance of the gear 12 and a braking force of the mechanical brake 21. The electrical holding force 23 is induced by means of the servo motor 4.

[0035] In a speed range between 0 km / h and v1, the required motor current to generate the electrical holding force 23 is not necessary due to the required holding force F, which is lower than the electrical holding force 23. Thus, the holding force F can be achieved exclusively with the help of the mechanical holding force 22. If the speed v1 is exceeded, the electrical holding force 23 must be activated to ensure the secure positioning of the air guide element 2.

[0036] If the maximum holding force is exceeded, for example by a person supporting themselves on the air guide element 2, since the gear is not designed to be self-locking, the actuating shaft 5 can perform the second rotation and the air guide element 2 can be pushed from its current position into a further position arranged in the direction of its closed position, without the gear 12 and / or the kinematics 26 or the actuator 4 in particular being damaged. List of reference symbols 1 control element 2 air guide element 3 Motor vehicle 4 actuator 5 Control shaft 6 housings 7 Longitudinal axis 8 First end of the control shaft 9 Second end of the control shaft 10 First housing part 11 Second housing part 12 gearboxes 13 First gear stage 14 Second gear stage 15 First snail 16 First worm gear 17 Second snail 18 Second worm gear 19 Connection 20 Wave 21 Brake 22 Mechanical holding force 23 Electrical holding force 24 Output shaft 25 gearbox bearings 26 Kinematics F Holding force v speed v1 Speed ​​at the time of exit

Claims

[1] Actuating element for an air guiding element of a motor vehicle, wherein the air guiding element (2) is adjustable in its position relative to the motor vehicle (3) between a first position and a second position, wherein for adjustment the actuating element (1) is operatively connected to a kinematics (26) of the air guiding element (2), and wherein the actuating element (1) has a servomotor (4) and an actuating shaft (5) which is operatively connected to the kinematics (26), and wherein a gear (12) which is not self-locking is formed between the actuating shaft (5) and the actuating motor (4), characterized byin that, in order to ensure secure positioning of the air guiding element (2), the gear (12) is designed to be efficient, wherein the gear (12) has a high internal friction and, at the same time, a relatively high efficiency, such that at certain load points, no reverse rotation of the actuating shaft (5) is possible, and wherein the gear (12) is a helical gear. [2] Actuating element according to claim 1, characterized by that the efficiency of the gear (12) has a value greater than 0.

5. [3] Actuating element according to claim 1 or 2, characterized by that the gear (12) is designed for a reverse rotation of the actuating shaft (5) when a maximum load limit is exceeded. [4] Actuating element according to one of the preceding claims, characterized by that the gear (12) is a worm gear. [5] Actuating element according to one of the preceding claims, characterized by that the actuating element (1) has a brake (21). [6] Actuating element according to one of claims 3 to 5, characterized by that the maximum load limit is determined as a function of a maximum motor cogging torque and internal friction of the gear (12) and a braking torque of a brake (21). [7] Actuating element according to claim 5 or 6, characterized by that the brake (21) is a mechanical brake (21) and / or an electric brake (21). [8] Actuating element according to claim 7, characterized by that the mechanical brake (21) is a multi-disk brake or a loop band brake. [9] Actuating element according to claim 7, characterized by that the electric brake (21) is designed in the form of a DC motor, in particular in the form of a brushless DC motor.

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