The present invention relates to mechanisms for controlling movable panels carried on motor vehicles. More particularly, the present invention relate to power drive mechanisms for trunk lid and lift gate assemblies which are controllable for selectively driving a movable panel between open and closed positions.
As motor vehicles characterized by their utility become a mainstream choice, consumers demand certain luxuries primarily associated with passenger cars, either due to their inherent design and/or size. One of the features desired by consumers is the automated movement of such items as sliding doors and lift gates. While features offering automated motion are available, the designs for mechanisms used to accommodate manual overrides are lacking in capability and functionality. Further, the systems consume space within the motor vehicle that makes the interior less efficient and aesthetically less appealing.
Continued demand for enhanced passenger convenience and comfort has caused automobile manufacturers to expand power assist functions in most vehicle systems involving movable panels. In most cases, the power assist is implemented via an electric motor and geared transmission mechanically coupled with an associated movable panel whereby the vehicle operator can control the system by simply actuating a control switch.
In addition to more traditional truck-type movable panels, motor vehicles of the hatchback and van configuration typically include an access opening at the rear of the vehicle body and a lift gate selectively opening and closing the access opening. The lift gate is typically manually operated and specifically requires manual effort to move the gate between open and closed positions. Various attempts have been made to provide power actuation for the lift gate but none of the prior art power actuation systems have realized any significant degree of commercial success since they have either been unduly complicated, relatively expensive, or maintenance prone.
It is generally known to provide a power drive system for driving a movable panel such as a sliding door in movement between an open position and a closed position, where the driving arrangement accommodates shifting between manual operation and positively driven powered operation of the panel at any position along its path of movement while providing a control responsive to an overload to stop panel movement in the event an object is trapped by the closing panel. These types of power drive systems are especially well adapted for use in operating the sliding door of a van-type vehicle. Typically, a power drive system is capable of driving an output member coupled to the door to drive the door in either direction over a relatively long working stroke. The coupling between the output member and the door can take the form of a positive mechanical interconnection between the motor and the door operable in either direction of movement as required. Additional problems may be presented where the power drive system is to power the sliding door of a van-type vehicle over and above the forgoing considerations applicable to sliding doors in general.
The power drive system of a sliding door in a van-type vehicle application is conventionally mounted on either longitudinally extending side of the van and the system may be operated by control switches accessible from the driver's seat. However, there are many occasions where the driver may desire to open or close the door manually, such as when the driver is outside the van loading or unloading articles through the sliding door and the controls are out of reach. A positively mechanically linked connection between the door and power source will interfere with manual operation of the door and may disturb a relationship between the door and drive relied on by the control system to sense the position of the door along its path of travel.
Translation of a vehicle panel typically requires an efficient set of machine elements and clutches to allow the panel to overhaul the system. Yet the driving system must drive efficiently and not offer a significant resistance when being overhauled. A soft coupling may be employed to assure system loads remain in the range of acceptable machine element loads. A ball nut is a highly efficient machine element when used with a ball screw. However, the ball screw is rigid and expensive when used in applications requiring significant travel, while generally being incapable of accommodating movement along a path that is not linear.
The present invention provides a drive unit for a movable panel such as a vehicle trunk lid which includes a rotatable drive element and a nonrotatable drive element which is threadably engaged with the rotatable drive element for controlled bi-directional displacement of the panel. One or both of the drive elements is elongated. An electric motor drivingly engages the rotatable drive element. A first mounting device pivotally interconnects the rotatable drive element to a relatively fixed point of a host vehicle wherein the rotatable drive element is axially restrained but is free to rotate about the axis of elongation. A second mounting device pivotally interconnects the non-rotatable drive element to the movable panel wherein the non-rotatable drive element is both axially and rotatably restrained. Finally, means are provided to energize the motor to affect bi-directional control of the drive unit.
According to another aspect of the invention, biasing means such as concentric compression/tension coil springs, are provided to offset the loading imposed by the movable panel. This arrangement has the advantage of allowing the motor and certain drive unit components to be downsized.
According to still another aspect of the invention, a clutch is provided which is operative to momentarily disconnect the electric motor from the second mounting device in response to sensing excessive loads in the system. This arrangement protects the drive system and associated vehicle from damage/failure due to abusive manual overriding of the movable panel.
According to yet another aspect of the invention, a resilient damper is inserted between the motor armature output shaft and the concentric worm shaft. This feature has the advantage of absorbing momentary torsional loads to protect the drive system.
According to still yet another aspect of the invention, a resilient damper is series inserted between the motor armature output shaft and the concentric worm shaft. This feature has the advantage of axially isolating the output and worm shafts by continuously urging them axially apart whereby back drive forces are isolated from the motor armature.
These and other features and advantages of this invention will become apparent upon reading the following specification, which, along with the drawings, describes preferred and alternative embodiments of the invention in detail.
The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:
Although the drawings represent embodiments of the present invention, the drawings are not necessarily to scale and certain features may be exaggerated in order to illustrate and explain the present invention. The exemplification set forth herein illustrates an embodiment of the invention, in one form, and such exemplifications are not to be construed as limiting the scope of the invention in any manner.
Vehicles in general, and particularly passenger vehicles such as automobiles employ numerous movable panels for various applications to provide openings and access within and through defined portions of the vehicle body. To enhance operator convenience and safety, the automobile industry frequently employs varied control systems for such functions as hatch lift gates, trunk and hood deck lids, sliding and hinged doors, sun roofs, window regulators, and the like. Mechanical advantage is often provided by sector (gear) drives, cable drives chain drives, belt drives and jack screw drives. Such drives can be operated manually, with power assist, or by both. Current development focus within the automobile industry is largely on improving popular systems through weight and part count reduction, packaging efficiency, system noise, back drive effort, cost (parts and labor) and ease of assembly and service. The present invention addresses all of these issues.
For purposes of descriptive clarity, the present invention is herein described in the context of one specific application, the power assisted opening and closing of the trunk (boot) lid of a conventional passenger automobile. Upon reading the present specification, it will become clear that the present invention can be applied with success in numerous systems and applications. Accordingly the application is to be considered as descriptive in nature and not limiting. Furthermore, the several embodiments of the invention are depicted in a quasi-schematic form to simplify and shorten the specification without departing from a complete and cogent presentation.
Referring to
The pivoted arm assembly 18 which is not illustrated includes an arm having one end attached to the trunk lid 12 and one end hinged to the vehicle body 12 by a pivot pin for swinging movement about an axis extending transversely to the vehicle body 12. The second (illustrated) pivoted arm assembly 18 has a similar arm 20 that also has one end 24 hinged to the vehicle body 12 by a mounting bracket 28 for swinging movement about the same transverse axis. The deck lid 16 is rigidly secured to the two arms 20 at opposed ends 22.
Arms 20 each have an opposite end 24 pivotally affixed to the body 12 via a pin 26 and a mounting bracket 28 within rear trunk space 14. The illustrated pivoted arm assembly 18 is frequently referred to as a goose neck hinge.
A power deckled drive system 30 is mounted within the rear trunk space 14 and operates to swing the arm 20 and trunk lid 16 about the axis of pin 26 between the closed and open positions in response to operator initiated signals received from a controller 32. The drive system 30 includes an elongated, externally threaded rotatable drive element or jackscrew 34 which threadably engages an internally threaded concentric plastic nut 36 fixedly carried with a second relatively non-rotatable drive element or jackscrew guide tube 38. The jackscrew 34 has a spiral gearform with a pitch angle which is selected to be back drivable without the need for a clutch. The free end (right hand most as hand most as illustrated) of the jackscrew 34 carries a screw guide 40 in sliding engagement with the inner diameter surface of the guide tube 38. The screw end guide 40 is formed of nylon or other suitable material and functions to prevent buckling as well as to reduce system noise and ensure smooth sliding operation.
An electric motor assembly 42 is carried by a motor bracket 44 which, in turn, is interconnected to the body 12 by a connecting pin 46 and a mounting bracket 48. The motor assembly 42 includes an electric motor 50 in circuit with the controller 32 and a geared transmission or output drive 52. The left hand portion of the jackscrew 34 extends through the motor output drive 52 to engage a rightwardly facing thrust bearing 54 formed by the motor bracket 44. The motor output drive 52 engages the jackscrew 34 for controlled bi-directional rotation about its axis of elongation in response to control signals from the controller 32.
The right hand most end of the guide tube 38 terminates in an end cap 56 which is interconnected to a bracket 58 affixed to an intermediate portion of the arm 20 by a connecting pin 60. The bracket 58 is spaced from the end 24 of arm 20 to provide an appropriate mechanical advantage.
Optionally, an encoder wheel can be carried for rotation with the jackscrew 34 which is in register with a relatively stationary optical sensor configured to provide jackscrew positional feedback to the controller 32.
As depicted in
In application, the motor 50 is typically actuated by a suitable control readily accessible to the operator of the vehicle 10, such, for example, as a hand-held fob (not illustrated) of the type employed to carry the vehicle keys. The control is such that when the deck lid 16 is closed, operation of the motor 50 rotates the jackscrew 34 in one direction, pushing the guide tube 38 axially away, increasing the separation between connection pins 46 and 60 at opposed ends of the drive system 30 to open trunk lid 16, and when the trunk lid 16 is open, the control reverse rotates the jackscrew 34 to decrease the separation between the connection pins 46 and 60 to close the trunk lid 16. Empirical test data has shown that for a typically configured vehicle 10, a nominal range of translation of the actuation axis of the drive system 30 about pivot pin 46 approximates 10°. The pitch of the threads formed in the jackscrew 34 and the nut 36 are selected effect minimal back drive force to enable manual override operation of the drive system without risk to the operator or the system.
In operation, the electric motor assembly 42 drives the jackscrew 34. As a result of rotation of jackscrew 34, nut 36 and guide tube 38 translate axially to extend or reduce the overall length of the drive system 30. The arrangement of
Referring to
Referring to
The embodiment of
The gear set depicted in
Definitionally a “single stage gearbox” is deemed to include a gear power transmission containing a single gear set. The gears are cooperatively engaged for transmitting forces there between. A driven input is associated with one of the gears and a driving output is associated with the other of the gears.
Referring to
Except as described herein, the alternative embodiment of the invention depicted in
The power deckled drive system 82 is mounted within the rear trunk space 88 and operates to swing the arm 94 and trunk lid 90 through a range of about 90° about the axis of pin 102 between the closed and open positions in response to operator initiated signals received from a controller (not illustrated). The drive system 82 includes an elongated, externally threaded rotatable drive element or jackscrew 104 which threadably engages an internally threaded concentric jackscrew nut 106 fixedly carried for relative non-rotation by arm 94 at an intermediate location there along. The jackscrew 104 has a spiral gearform with a pitch angle which is selected to be back drivable without the need for a clutch. The jackscrew nut 106 is operatively interconnected for movement with the mid-portion of the arm 94 by a gimbal-type device 108 with has a laterally extending opposed pair of pivot pins 110 (parallel to pin 102) and a vertically extending opposed pair of pivot pins 112. This arrangement provides freedom of relative rotation in two normal axes between the jackscrew nut 106 and the adjacent portion of the associated arm 94. The free end (right hand most as illustrated) of the jackscrew 104 carries an end stop 114 operative to limit relative rightward travel of the jackscrew nut 106 as it traverses axially along the along the jackscrew 104.
An electric motor assembly 114 is carried by a motor bracket 116 which, in turn, is interconnected to the body 86 by a connecting pin 118 and a mounting bracket 120. The motor assembly 114 includes an electric motor 122 in circuit with the controller and a geared transmission or output drive 124. The left hand portion of the jackscrew 104 extends through the motor output drive 124 to engage a rightwardly facing thrust bearing 126 formed by the motor bracket 120. The motor output drive 124 engages the jackscrew 104 for controlled bi-directional rotation about its axis of elongation in response to control signals from the controller.
An encoder wheel 128 can be carried for rotation with the jackscrew 104 which is in register with a relatively stationary optical sensor 130 configured to provide jackscrew positional feedback to the controller. Optionally, the encoder could be a magnetic encoded wheel with Hall effect sensors, or other suitable devices.
As depicted in
The embodiment of the present invention depicted in
Referring to
Except as described herein, the second alternative embodiment of the invention depicted in
The power deckled drive system 132 is mounted within the rear trunk space 138 and operates to swing the arm 144 and trunk lid 140 through a range of about 90° about the axis of pin 150 between the closed and open positions in response to operator initiated signals received from a controller (not illustrated). The drive system 132 includes an elongated, externally threaded rotationally fixed drive element or jackscrew 154 which threadably engages an internally threaded concentric jackscrew nut integrated within a worm gear 156 carried within an electric motor assembly 158. In this alternative embodiment of the invention, the jack screw 154 is carried for relative non-rotation by arm 144 at an intermediate location there along. Specifically, the right hand end of the jack screw 154 is bifurcated to form a fork 160 which is affixed to an intermediate portion of arm 144 by a mounting bracket 162 and connecting pin 164 for translation therewith.
The jackscrew 154 has a spiral gearform with a pitch angle which is selected to be back drivable without the need for a clutch. The motor assembly 158 includes an electric motor 166 and a geared output drive 168 including the worm gear 156. The outer circumferential surface of the worm gear 156 has a spur or helical gear formed thereon for driving engagement with a worm formed on the motor's armature (refer
The electric motor assembly 158 is carried by a pivoting bracket 174 which, in turn, is interconnected to the body 136 by a connecting pin 176 and a mounting bracket 178. The motor assembly 158 includes the electric motor 166 in circuit with the controller (not illustrated) and the geared transmission or output drive 168. The motor output drive 168 engages the jackscrew 154 for controlled bi-directional rotation about its axis of elongation in response to control signals from the controller.
As depicted in
The embodiment of the present invention depicted in
Referring to
The slip clutch 196 releasably interconnects the end of the jackscrew 192 with the output gear 190 whereby during normal operation, the output gear 190 and the jackscrew 192 rotate in unison during powered opening and closing of the associated trunk lid. When high level torsion forces are applied to the jackscrew 192 through back driving the drive system 180 in response to abusive manual operation of the associated trunk lid and hinge, the slip clutch 196 momentarily releases its inter-engagement between the jackscrew 192 and output gear 190 to avoid mechanical damage to the system. When the transient over forces subside, the slip clutch re-engages the jackscrew 192 and output gear 190, When the slip clutch breaks free, there is still friction so the panel will not free fall. Alternatively, a free wheeling clutch can also be employed.
Referring to
A slip clutch assembly 216 interconnects the free, left hand most end of the guide tube 208 and the end fitting 210. The slip clutch assembly 216 includes an inner base member 218 which is affixed to the end fitting 210 and extends rightwardly there from. An outer slip clutch housing member 220 is carried concentrically externally of the base member 218 and is axially restrained in position by a rightwardly facing step 2 formed in the base member 218 and an opposed snap ring 224. The outer circumferential surface of the outer clutch housing 220 is fitted within the hollow end of the guide tube 208 and axially restrained in position by left and right upsets 226 and 228, respectively, formed in the guide tube.
The slip clutch 216 releasably interconnects the end of the guide tube 208 with the end fitting 210 whereby during normal operation, the guide tube 208 and the end fitting are locked together during powered opening and closing of the associated trunk lid. When high level torsion forces are applied to the jackscrew 204 through back driving the drive system 202 in response to abusive manual operation of the associated trunk lid and hinge, the slip clutch 216 momentarily releases its interengagement between the guide tube 208 and the end fitting to avoid mechanical damage to the system. When the transient over forces subside, the slip clutch 16 re-engages the guide tube 208 and end fitting 210.
Both of the slip clutches 196 and 216 of
Referring to
Referring to
The electric motor 266 includes a stator assembly 282 mechanically coupled to the gear box housing 268 and an armature disposed for rotation therein. The armature has an output shaft 284 which is axially in register with a worm shaft 286 extending through the gear box housing 268 for engaging a drive gear (not illustrated). Refer
In assembly, the spider 302 serves to space the opposed coupler halves wherein the base portion 304 provides axial isolation and the finger portions 304 are interposed between adjacent pairs of interdigitated fingers 298 and 300 to provide circumferential isolation.
In application, motor 282 induced torque is transferred from fingers 300 of coupler half 294 to the fingers 298 of the coupler half 290 for driving the worm shaft 286. Transients or torsional shock loads are absorbed by momentary compression and relaxation of the finger portions 306 of the spider 302. The axial component of forces transferred to the worm shaft 286 from the motor 266 are transferred into the housing 268 through a bushing surface (not illustrated). The base portion 304 of the spider 302 provides a limited axial degree of freedom of the worm shaft 286 in the direction toward the motor 266. Thus, axial shock loads resulting from back driving the drive system 262 are transferred from the worm shaft 286 to the gear box housing 268 and are contained therein. No additional thrust protection is thus required for the motor 266. This arrangement separates some of the vibration of the motor to the worm, so less vibration is transmitted through the gearbox for a quieter drive unit. Further it provides modularity to the design, keeping cost lower, and enabling the swap-out of different motors with different motor performance characteristics to achieve different drive unit performances. This has a distinct advantage in allowing electric motors of standard design to be employed in the present invention, further reducing system cost.
It is to be understood that the invention has been described with reference to specific embodiments and variations to provide the features and advantages previously described and that the embodiments are susceptible of modification as will be apparent to those skilled in the art.
Furthermore, it is contemplated that many alternative, common inexpensive materials can be employed to construct the basis constituent components. Accordingly, the forgoing is not to be construed in a limiting sense.
The invention has been described in an illustrative manner, and it is to be understood that the terminology, which has been used is intended to be in the nature of words of description rather than of limitation.
Obviously, many modifications and variations of the present invention are possible in light of the above teachings. For example, the illustrated embodiments could be attached at their respective ends employing hinge ball studs such as those employed in hatch gas support struts. It is, therefore, to be understood that within the scope of the appended claims, wherein reference numerals are merely for illustrative purposes and convenience and are not in any way limiting, the invention, which is defined by the following claims as interpreted according to the principles of patent law, including the Doctrine of Equivalents, may be practiced otherwise than is specifically described.
This patent application is a continuation of U.S. patent application Ser. No. 12/671,754, filed Sep. 19, 2011, now U.S. Pat. No. 9,222,296. U.S. patent application Ser. No. 12/671,754 in turn is a national stage filing under 35 U.S.C. 371 of International Application No. PCT/US2008/009429, filed Aug. 6, 2008, and claims priority to U.S. Provisional Patent Application No. 60/963,589, filed Aug. 6, 2007. The above referenced applications are hereby incorporated by reference.
Number | Date | Country | |
---|---|---|---|
60963589 | Aug 2007 | US |
Number | Date | Country | |
---|---|---|---|
Parent | 12671754 | Sep 2011 | US |
Child | 14981405 | US |