Patent Application
20220290482
The present disclosure relates to a power strut assembly for raising and lowering a panel of an automotive vehicle.
In pickup trucks, the cargo area is accessible from the rear of the vehicle via a tailgate that can be lowered for access and raised for securing the load. It has become customary to motorize the tailgate so that raising and lowering the tailgate involves merely the push of a button.
Existing power tailgate drive units rely on access to the hinge or to a special linkage to drive the tailgate resulting in required body panel modifications or excessive packaging space internal to the body, which results in an increase in weight and cost while causing a decrease in structural integrity.
It is therefore desirable to provide a power strut assembly that is suitable for actuating a tailgate with a reduced packaging space requirement.
According to the present disclosure, a power strut assembly for raising and lowering a panel of an automotive vehicle comprises a strut housing defining two parallel axes, one of which is a motor rotary axis and the other one of which is a spindle rotary axis. A drive motor disposed in the strut housing has an output shaft rotatable by the drive motor about the motor rotary axis. A drive spindle with a threaded section at least partially disposed in the strut housing is rotatable about the spindle rotary axis parallel to the motor rotary axis. A spindle nut is arranged on the threaded section of the drive spindle. A motor-spindle transmission for transmitting a rotation of the output shaft to the drive spindle includes a motor wheel secured to the output shaft and configured to be rotated by the drive motor about the motor rotary axis and a spindle wheel rigidly coupled to the drive spindle and configured to rotate about the spindle rotary axis. The motor wheel and the spindle wheel extend in a common plane of rotation.
The motor wheel may be a motor gear and the spindle wheel may be a spindle gear, wherein the motor gear and the spindle gear have toothed profiles that mesh with each other. The motor gear and the spindle gear may be spur gears. Alternatively, the motor gear and the spindle gear may be helical gears for enhancing the torque transmission.
The motor wheel and the spindle wheel may alternatively be coupled via a drive belt.
A nut tube may be affixed to the spindle nut and have a free end extending outward from the strut housing beyond the drive spindle with an end plug shaped as a movable attachment element for attachment to a movable vehicle part.
Optionally, a compression spring surrounding the nut tube may axially bias the nut tube in a direction away from the spindle gear.
In one example, the motor wheel and the spindle wheel have identical diameters. For transmitting a greater torque at a lower speed, the motor wheel may have a smaller diameter than the spindle wheel.
For accommodating the motor wheel and the spindle wheel, the strut housing may have a first end cap defining a transmission space. The first end cap may have an axial protrusion shaped as a stationary attachment element for attachment to a stationary vehicle part.
At an opposite, second end of the strut housing, a second end cap may have a cable opening, through which a cable bundle connected to the drive motor extends out of the strut housing. The cable opening may be fitted with a flexible gasket guiding and protecting the cable bundle. The second end cap may have a further opening, through which a nut tube affixed to the spindle nut extends out of the strut housing.
The strut housing may form a spindle tube and a motor tube and optionally be reinforced by stiffening ribs extending between the motor tube and the spindle tube.
A motor bearing coaxial with the motor rotary axis may be mounted in the strut housing between the drive motor and the motor wheel, and a spindle bearing coaxial with the spindle rotary axis may be mounted in the strut housing between the threaded section of the drive spindle and the spindle wheel.
The drive motor may be contained in a motor housing fixedly held in the strut housing, wherein the motor housing further holds a reduction gear arrangement.
further details and benefits will become apparent from the following description of three examples by way of the appended drawings. The drawings are provided for purely illustrative purposes and are not intended to limit the scope of the present invention.
In the drawings,
Referring to
As best seen in
A motor-spindle transmission 44 is arranged at the housing end covered by the first end cap 16 that defines a transmission space. The motor-spindle transmission 44 transmits a rotation of the output shaft 28 to the drive spindle 30 and includes a motor wheel 46 secured to the output shaft 28 and configured to be rotated by the drive motor 26 about the motor rotary axis M. A spindle wheel 48 is rigidly coupled to the drive spindle 30 and configured to rotate about the spindle rotary axis S. As shown in
In the examples of
In the example of
The nut tube 36 has a free end extending outward from the strut housing 12 beyond the drive spindle 30 and has an end plug 58 shaped as a movable attachment element for attachment to a movable vehicle part. In particular in examples, in which the motor wheel 46 and the spindle wheel 48 are of the same size as shown in
As shown in
The second end cap 18 in not present in all examples. It is shown in the first example having a spindle tube 22 as part of the strut housing 12. The second end cap 18 has a cable opening 64, through which a cable bundle 66 extends. The cable bundle 66 is connected to the drive motor 26 and terminates in an electric connector 68 outside of the strut housing 12. The cable opening 64 is fitted with a flexible gasket 70 guiding and protecting the cable bundle 66. The second end cap 18 has a tube opening 72, through which the nut tube 36 extends out of the strut housing 12.
In contrast, the second end cap 18 is not required in arrangements that feature a compression spring 60 as shown in the third example of
A spindle bearing 74 coaxial with the spindle rotary axis S is mounted in the strut housing 12 and supports the drive spindle 30 between the threaded section 32 and the spindle wheel 48. The outer circumference of the spindle bearing 74 is press-fitted into the strut housing 12 that extends around the spindle bearing 74 or is otherwise affixed.
The drive motor 26 is contained in a motor housing 76 fixedly held in the strut housing 12. The motor housing 76 includes not only the electric drive motor 26, but also a speed reduction gear assembly 80 for increasing the torque of the output shaft 28. A suitable compact reduction gear assembly designed as a two-stage planetary gear box is, for example, disclosed in U.S. Pat. No. 9,822,843, with coaxial input and output axes. The output shaft 28 of the drive motor 26 is supported by a motor bearing 78 arranged between the motor housing 76 and the motor wheel 46. The outer circumference of the motor bearing 78 is press-fitted into the strut housing 12 or otherwise affixed.
Various features of the three described examples are interchangeable, and the present invention is not limited to any feature combinations within individual examples. Accordingly, for example, the slide tube 82 and the compression spring 60 may still be accommodated inside a spindle tube 22 of the strut housing 12, the drive belt 56 may be used with a motor wheel 46 and a drive wheel of equal size with or without a compression spring 60, spur gears or helical gears may be used for equally sized or differently sized motor gear 52 and spindle gear 54, with or without a compression spring 60. Accordingly, the various options have been discussed by topic and not in the order of the individual examples shown in the drawings.
While the above description constitutes the preferred embodiments of the present invention, the invention is susceptible to modification, variation and change without departing from the proper scope and fair meaning of the accompanying claims.
