Linear power drive unit for vehicle doors

Abstract

A power drive unit for opening and closing a vehicle door is described. A bracket is configured to couple to one of the body and the door. A gear housing is configured to couple to the other one of the body and door. A link arm is operatively coupled to the bracket at a first end and pivotally coupled to a carrier at a second, distal end. A leadscrew and guide shaft are coupled to the gear housing spaced apart from each other. A drive motor is operatively coupled to the leadscrew. The carrier is configured to travel along the guide shaft and leadscrew in a door open direction and in a door closed direction as the leadscrew rotates in a nut fixed in relation to the carrier. When the drive motor is driven in a first direction, the carrier travels in the door open direction and vice-versa.

Description

LINEAR POWER DRIVE UNIT FOR VEHICLE DOORSCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims priority from United States Provisional Patent Application Number 63 / 777,348 filed on March 25, 2025, the contents of which being incorporated herein by reference.TECHNICAL FIELD

[0002] This disclosure relates to door opening systems for automotive vehicles, and more particularly to a linear power drive unit for a vehicle door.BACKGROUND

[0003] A vehicle door is usually manually opened or closed by pushing or pulling the door without the benefit of a power drive unit. A door check is typically used to hold the vehicle door in a door open position. To assist with opening and closing vehicle doors, power drive units for vehicle doors are increasingly being provided on vehicles to move the doors between open and closed positions. However, conventional power drive units are rather complex and often occupy too much space (and add weight), especially when used in addition to door checkers.

[0004] It would be helpful to provide power drive units that help to overcome such problems.SUMMARY

[0005] According to some embodiments, there is provided a power drive unit for opening and closing a vehicle door comprising a bracket, a gear housing, a link arm, a leadscrew and a drive motor. The bracket is configured to couple to one of the vehicle body and the vehicle door. The gear housing is configured to couple to the other one of the vehicle body and the vehicle door. The link arm is operatively coupled to the bracket at a first end and is pivotally coupled to a carrier at a second end distal to the first end. The leadscrew and a guide shaft are coupled to the gear housing and spaced apart from each other. The drive motor is operatively coupled to the leadscrew. The carrier is operatively coupled to the guide shaft and to the leadscrew, the carrier being configured to travel along the guide shaft and the leadscrew in a door open direction and in a door closed direction opposite the door open direction as the leadscrew rotates in a nut fixed inrelation to the carrier. When the drive motor is driven in a first direction, the carrier travels in the door open direction. When the drive motor is driven in a second direction opposite the first direction, the carrier travels in the door closed direction.

[0006] According to some embodiments, the power drive unit further comprises an anti-rotation member coupled to the carrier or incorporated into at least one housing face proximate the leadscrew and configured to engage the at least one housing face or at least one earner face to resist torsional displacement of the leadscrew during operation of the drive motor. According to some embodiments, the at least one housing face is an interior face of one or more of the gear housing and a carrier housing. According to some embodiments, the anti-rotation member comprises a first energy storage member configured to resiliently engage the at least one housing face or to resiliently engage the at least one carrier face. According to some embodiments, the first energy storage member comprises an S-shaped spring. According to some embodiments, the anti-rotation member further comprises at least one resilient bumper. According to some embodiments, the anti-rotation member comprises: a cam-shaped member configured to abut the at least one housing face when in a first orientation, and a second energy storage member coupled to the cam-shaped member and configured to resiliently position the cam-shaped member to the first orientation. According to some embodiments, the second energy storage member comprises a leaf spring which resiliently abuts a pre-load protrusion of the carrier.

[0007] According to some embodiments, an output shaft of the drive motor is coupled to a worm gear configured to mesh with a helical gear that is operatively coupled to the leadscrew. According to some embodiments, the power drive unit further comprises an anti-backlash member having a third energy storage member configured to apply a pre-load to the worm gear to push the worm gear into meshing engagement with the helical gear. According to some embodiments, the anti-backlash member is configured to apply the pre-load at a location along the worm gear distal to the drive motor.

[0008] According to some embodiments, the power drive unit further comprises an oblong bushing coupled to the worm gear and configured to support the worm gear such that movement along a first transverse axis of the worm gear is more limited than movement along a second transverse axis of the worm gear.

[0009] According to some embodiments, the third energy storage member comprises a spring, preferably a coil spring, or an elastomeric member.

[0010] According to some embodiments, the power drive unit further comprises a first torque transfer member operatively coupled to the output shaft and the worm gear. According to some embodiments, the power drive unit comprises a second torque transfer member operatively coupled to the helical gear and the leadscrew. According to some embodiments, at least one of the first torque transfer member and the second torque transfer member comprises two non-resilient members rotationally coupled to each other with a resilient member therebetween. According to some embodiments, the resilient member comprises an elastomeric material.

[0011] According to some embodiments, the power drive unit further comprises an electronic control unit configured to actuate the drive motor.

[0012] According to some embodiments, the power drive unit further comprises at least one bushing positioned between the guide shaft and the carrier.

[0013] According to some embodiments, there is provided a power drive unit for opening and closing a vehicle door comprising a bracket, a gear housing, a link arm, a leadscrew, a drive motor and an anti-backlash member. The bracket is configured to couple to one of a vehicle body and the vehicle door. The gear housing is configured to couple to the other one of the vehicle body and the vehicle door. The link arm is operatively coupled to the bracket at a first end and is pivotally coupled to a earner at a second end distal to the first end. The leadscrew is coupled to the gear housing. The drive motor is operatively coupled to the leadscrew and having an output shaft operatively coupled to a worm gear, the worm gear being configured to mesh with a helical gear operatively coupled to the leadscrew. The anti-backlash member has a backlash energy storage member configured to apply a pre-load force to the worm gear to push the worm gear into meshing engagement with the helical gear. The carrier is operatively coupled to the leadscrew and is configured to travel along the leadscrew in a door open direction and in a door closed direction opposite the door open direction as the leadscrew rotates in a nut fixed in relation to the carrier. When the drive motor is driven in a first direction, the carrier travels in the door open direction. When the drive motor is driven in a second direction opposite the first direction, the carrier travels in the door closed direction.

[0014] According to some embodiments, the output shaft is operatively coupled to a first end of the worm gear via a ball bearing and the anti-backlash member is configured to apply the preload force to the worm gear at a worm gear location distal to the first end of the worm gear.

[0015] According to some embodiments, the power drive unit further comprises an oblong bushing coupled to the worm gear and configured to limit movement of the worm gear along a first transverse axis and to allow some movement of the worm gear along a second transverse axis. According to some embodiments, the oblong bushing is configured to allow some movement of the worm gear along the second transverse axis when torque output from the drive motor exceeds a limit. According to some embodiments, the oblong bushing is coupled to the worm gear proximate the applied pre-load force.

[0016] According to some embodiments, the anti-backlash member comprises a backlash housing and an abutting member. The backlash housing is configured to fixedly engage with the gear housing. The abutting member is moveably coupled to the backlash housing via the backlash energy storage member. The backlash energy storage member is biased to compel the abutting member into engagement with one or more of the worm gear and the output shaft to apply the pre-load force to the worm gear. According to some embodiments, the backlash housing comprises one or more retention clips configured to fixedly engage with the gear housing. According to some embodiments, the abutting member comprises a plunger. According to some embodiments, the backlash energy storage member comprises one or more of a spring and an elastomeric member. According to some embodiments the spring comprises a coil spring.

[0017] According to some embodiments, the power drive unit further comprises a first torque transfer member operatively coupled to the output shaft and the worm gear. According to some embodiments, the power drive unit comprises a second torque transfer member operatively coupled to the helical gear and the leadscrew. According to some embodiments, at least one of the first torque transfer member and the second torque transfer member comprises two non-resilient members rotationally coupled to each other with a resilient member therebetween. According to some embodiments, the resilient member comprises an elastomeric material.

[0018] Further aspects of the claimed subject matter will be apparent from the following description and explanations.BRIEF DESCRIPTION OF THE DRAWINGS

[0019] For a better understanding of the various embodiments described herein and to show more clearly how they may be carried into effect, reference will now be made, by way of example only, to the accompanying drawings in which:

[0020] FIG. 1 depicts perspective view of a power drive unit for opening and closing a vehicle door, according to non-limiting embodiments;

[0021] FIG. 2 depicts a cross-sectional view of the power drive unit of FIG. 1 taken along section A- A, according to non-limiting embodiments;

[0022] FIG. 3 depicts a partial sectional view of the power drive unit of FIG. 1, according to non-limiting embodiments;

[0023] FIG. 4A depicts a perspective sectional view of the power drive unit of FIG. 1, according to non-limiting embodiments;

[0024] FIG. 4B depicts a front view of the power drive unit of FIG. 4A;

[0025] FIG. 5 depicts an enlarged view of the sectional view of FIG. 3;

[0026] FIG. 6A depicts a schematic of the power drive unit of FIG. 1, according to non-limiting embodiments;

[0027] FIG. 6B depicts an enlarged view of an anti-rotation member, according to a first set of non-limiting embodiments;

[0028] FIG. 6C depicts an enlarged view of an anti-rotation member, according to a second set of non-limiting embodiments;

[0029] FIG. 7 depicts the anti-rotation member of FIG. 6B;

[0030] FIG. 8 depicts the anti-rotation member of FIG. 6C;

[0031] FIG. 9 depicts a perspective view of a power drive unit without an electronic control unit, according to non-limiting embodiments;

[0032] FIGS. 10A and 10B depict enlarged views of an anti-backlash member, according to a first set of non-limiting embodiments;

[0033] FIG. 11 depicts an enlarged sectional view of a power drive unit having an antibacklash member, according to a second set of non-limiting embodiments;

[0034] FIGS. 12A and 12B depict enlarged views of the anti-backlash member of FIG.11, according to non-limiting embodiments;

[0035] FIGS. 13A and 13B depict further enlarged sectional views of the anti-backlash member of FIG. 11 ;

[0036] FIG. 14 depicts loading on a worm gear of a power drive unit, according to nonlimiting embodiments;

[0037] FIGS. 15A and 15B depict cross-sectional views of a worm gear in an oblong bushing when the worm gear is under a low torque loading from the drive motor (FIG. 15 A) and when the worm gear is under a high torque loading from the drive motor (FIG. 15B), according to non-limiting embodiments;

[0038] FIGS. 16A and 16B depict a first torque transfer member coupled to the worm gear and drive motor output shaft, according to non-limiting embodiments; and

[0039] FIGS. 16C and 16D depict a second torque transfer member coupled to a helical gear and leadscrew, according to non-limiting embodiments.

[0040] The embodiments, examples and alternatives of the preceding paragraphs, the claims, or the following description and drawings, including any of their various aspects or respective individual features, may be taken independently or in any combination. Features described in connection with one embodiment are applicable to all embodiments, unless such features are incompatible.DETAILED DESCRIPTION

[0041] Described herein are linear power drive units (also referred to herein simply as power drive units) for opening and closing vehicle doors. The described power drive units can be installed within a vehicle’s door or a vehicle’s body pillar, in a similar area and mounting configuration to a standard door-check mechanism. A link arm may extend out of the power drive unit and be coupled to the vehicle’s body pillar or, according to some embodiments, be coupled to the vehicle’s door. Although the power drive units are described herein as being used with conventional side doors, it is understood that they may be used in other door applications. According to some embodiments, the described power drive units may comprise an electroniccontrol unit (ECU), which comprises the logic to drive the power drive unit via a drive motor. For those embodiments comprising an ECU, a printed circuit board (PCB) with a microcontroller may be included, along with the appropriate software. For those embodiments without an ECU, a small PCB with basic circuitry and electrical connections may be employed. Furthermore, the described power drive units may comprise certain features to help ensure smooth and quiet operation, as described further below.

[0042] It will be appreciated that numerous specific details are set forth in order to provide a thorough understanding of the exemplary aspects of the present application described herein. However, it will be understood by those of ordinary skill in the art that the exemplary aspects described herein may be practiced without these specific details. In other instances, well-known methods, procedures and components have not been described in detail so as not to obscure the exemplary aspects described herein. Also, the description is not to be considered as limiting the scope of the exemplary aspects described herein. Any systems, method steps, method blocks, components, parts of components, and the like described herein in the singular are to be interpreted as also including a description of such systems, method steps or tasks, components, parts of components, and the like in the plural, and vice versa. Further aspects of the invention will be apparent from the accompanying figures and explanations. The particular arrangement of the elements described herein may be modified as will be apparent to those skilled in the art.

[0043] Attention is directed to FIGS. 1 to 8. 10A and 10B, which depict a power drive unit 100 for opening and closing a vehicle door, according to non-limiting embodiments. Power drive unit 100 comprises a bracket, such as bracket 102, a gear housing 104, a link arm 106, a leadscrew 108 and a drive motor 112 (FIGS. 1 and 2). Bracket 102 is configured to couple to one or more of a vehicle body 1 (such as via the vehicle’s body pillar) and a vehicle’s door 2 (FIG. 2). According to some embodiments, bracket 102 comprises a bracket configured to pivotally couple link arm 106 to vehicle body 1 or vehicle door 2, such as a clevis bracket. Gear housing 104 is configured to be coupled to the other one of vehicle body 1 and vehicle door 2. Eink arm 106 is operatively coupled to bracket 102 at first end 114 and is pivotally coupled to carrier 116 at a second end 118 that is distal to first end 114. According to some embodiments, carrier 116 comprises a pivot post 120, link arm 106 has a bushing 122 at second end 118. According to someembodiments, there is provided a retaining fastener or washer 124 (or combination of the two). According to some embodiments, at the first end 114 coupled to bracket 102, link arm 106 comprises a bushing 126 and bracket 102 comprises pivot pin 128.

[0044] According to some embodiments, power drive unit 100 comprises features configured to provide additional stability and to aid in the alignment of components of power drive unit 100. According to some embodiments, power drive unit 100 further comprises guide shaft 110 spaced apart from leadscrew 108 (see, for example, FIG. 2). According to related embodiments, carrier 116 is operatively coupled to both guide shaft 110 and leadscrew 108. Carrier 116 is configured to travel along guide shaft 110 and leadscrew 108 in both a door open direction (DOD) and in a door closed direction (DCD) opposite the door open direction (FIG. 2). According to some embodiments, there is also provided at least one nut, such as nut 130, positioned between carrier 116 and leadscrew 108. Guide shaft 110 helps support carrier 116 and, according to some embodiments, nut 130. The described guide shaft 110 helps to avoid the complications often found in other known power drive units which rely on multiple guiding elements for alignment purposes. The Applicant has found that the described guide shaft 110 is typically a cost-effective component to achieve tight tolerances and smooth translation of link arm 106 parallel to leadscrew 108. For example, according to some embodiments, guide shaft 110 is configured to have a generally circular cross-sectional shape, typically making it suitable for fabrication using a high-volume precision machining process, such as centerless grinding or the like. According to some embodiments, guide shaft 110 has a circular, oval, square or rectangular shape. However, any suitable cross-sectional shape for guide shaft 110 is contemplated. For example, according to some embodiments, guide shaft 110 is provided with a generally smooth exterior cylindrical surface. According to some embodiments, at least one bushing, such as bushings 132 and 134, may be positioned between guide shaft 110 and carrier 116 to help provide a low-friction, tolerance compensated interface (FIG. 5). Any suitable material or combination of materials is contemplated for guide shaft 110. For example, according to some embodiments, guide shaft 110 is fabricated from steel with a chrome finish. Guide shaft 110 may be hollow or solid.

[0045] Drive motor 112 is operatively coupled to leadscrew 108. For example, according to some embodiments, output shaft 136 of drive motor 112 comprises or is otherwisecoupled to a worm gear 138 that is configured to mesh with a helical gear 140 that is operatively coupled to leadscrew 108 (FIGS. 4A and 4B). According to some embodiments, helical gear 140 comprises at least one cross-helical gear. As leadscrew 108 turns in nut 130, earner 116 is driven in the door open direction (DOD) or door closed direction (DCD). Any suitable drive motor is contemplated for drive motor 112. For example, according to some embodiments, drive motor 112 comprises a direct current (DC) motor, such as a 12 Volt DC motor. In operation, when the drive motor 112 is driven in a first direction, carrier 116 travels in the door open direction (DOD). Conversely, when drive motor 112 is driven in a second direction opposite the first direction, carrier 116 travels in the door closed direction (DCD).

[0046] According to some embodiments, one or more of worm gear 138 and output shaft 136 is rotatably supported by at least one bearing (such as ball bearing 137) (FIG. 4B). According to some embodiments, the at least one bearing may be coupled to a first end 139 of worm gear 138 proximate drive motor 112.

[0047] As drive motor 112 turns leadscrew 108. torque (T) about the leadscrew axis (LC) may be generated (FIG. 6A). Without correction, this torque (T) may twist carrier 116 about guide shaft 110 and out of proper alignment therewith, which would affect the ability of carrier 116 to travel smoothly along guide shaft 110 in the door open direction (DOD) and in the door closed direction (DCD). To help counter the leadscrew torque (T), the described power drive unit 100 may further comprise at least one anti-rotation member (generally, anti-rotation member 142, specifically, example anti-rotation member 142 A depicted in FIG. 6B or example anti-rotation member 142B depicted in FIG. 6C, as discussed below). Anti-rotation member 142 is coupled to earner 116 or is incorporated into at least one housing face proximate leadscrew 108 and is configured to engage at least one housing face or at least one carrier face (such as exterior carrier face 147) to resist torsional displacement of leadscrew 108 during operation of drive motor 112 (see, for example, FIG. 6A). The at least one housing face is typically an interior face of one or more of gear housing 104 and carrier housing 144. For example, according to some embodiments, the at least one housing face is an interior face of a groove 145 in carrier housing 144, such as interior housing face 146. According to some embodiments, anti-rotation member 142 is incorporated into one or more of the gear housing 104 and the carrier housing 144. For example,according to some embodiments, anti-rotation member 142 may be a molded feature of carrier housing 144 or a feature otherwise coupled to carrier housing 144. According to some embodiments, gear housing 104 and carrier housing 144 are one-piece (unitary). In addition to assisting with countering leadscrew torque (T), anti-rotation member 142 may also help to compensate for small differences in component tolerances and help ensure there is an essentially zero-play interface. According to some embodiments, anti-rotation member 142 is enabled to move along the at least one housing face (e.g., interior housing face 146 along groove 145 in carrier housing 144) without undesirable clearance. Furthermore, according to some embodiments, antirotation member 142 may help prevent clicking noises during load reversals (which may take place when switching between driven directions DOD and DCD of drive motor 112).

[0048] Anti-rotation member 142 may take a variety of forms. According to some embodiments, anti-rotation member 142 comprises a first energy storage member 148 configured to resiliently engage housing face 146 or to resiliently engage carrier face 147. For example, according to a first set of embodiments, anti-rotation member 142 comprises a post 150 coupled to first energy storage member 148A (FIGS. 6B, 7). According to some embodiments, first energy storage member 148A comprises an S-shaped spring wrapped around post 150 and biased into contact with the at least one housing face 146. For example, the S-shaped spring (first energy storage member 148 A) may fit within a groove in gear housing 104 or carrier housing 144 (such as groove 145) and is biased to apply a preload force (P) against the at least one housing face (such as interior housing face 146), which may help to ensure an essentially zero-play interface. The S-shaped spring (first energy storage member 148A) may comprise steel; however, any suitable material or combination of materials is contemplated. According to some embodiments, antirotation member 142 further comprises at least one resilient bumper. For example, according to some embodiments, anti-rotation member 142A comprises one or more resilient bumpers 152 which may be positioned between post 150 and the first energy storage member 148A (e.g., S-shaped spring). Resilient bumpers 152 are configured to provide at least some cushioning prior to the first energy storage member 148A reaching its end of travel (towards an outer surface of post 150), preventing clicking noises. Resilient bumpers 152 may comprise any suitable material or combination of suitable materials, such as rubber.

[0049] As noted above, according to some embodiments, anti-rotation member 142 may be incorporated into one or more of gear housing 104 and carrier housing 144. For example, first energy storage member 148 may comprise a resilient member coupled to housing face 146 or molded therefrom that is configured to resiliently engage carrier face 147. For example, according to some embodiments, carrier housing 144 is fabricated from a molded rubber or other resilient material and anti-rotation member 142 is configured as a resilient protrusion of housing face 146.

[0050] According to a second set of embodiments, anti-rotation member 142 comprises a cam-shaped member 154 configured to abut the at least one housing face (e.g., interior housing face 146) when in first orientation (see, for example, FIG. 8). According to some embodiments, cam-shaped member 154 may be sized and shaped such that when it is rotated to a certain angle, 0. about a vertical axis associated with anti-rotation member 142B (such as vertical axis V) at least one cam face (such as cam face 156) engages the at least one housing face (such as interior housing face 146). To pre-dispose the cam-shaped member 154 to the engaging orientation, a cam energy storage member 148B (also referred to herein as a second energy storage member 148B) is coupled to cam-shaped member 154 and is configured to resiliently position the cam-shaped member 154 to the first orientation. For example, as shown in FIG. 8, cam-shaped member 154 may fit within groove 145 of carrier housing 144 with a pre-load (i.e., biased against the carrier housing 144), which helps to ensure an essentially zero-play interface. According to some embodiments, the cam energy storage member 148B comprises a leaf spring which resiliently abuts a pre-load protrusion 158 of the carrier housing 144 (FIG. 8). Any suitable type of energy storage member is contemplated for the cam energy storage member 148B. For example, according to some embodiments, cam energy storage member 148B comprises one or more of a spring and an elastomeric member. Any suitable material or combination of materials is contemplated for cam-shaped member 154. For example, according to some embodiments, camshaped member 154 comprises plastic, steel, aluminum or any suitable combination thereof. According to some embodiments, a lubricant may be applied to the cam-shaped member 154 to reduce friction between the cam-shaped member 154 and the at least one housing face (such as interior housing face 146).

[0051] According to some embodiments, power drive unit 100 further comprises an electronic control unit (ECU) 160 configured to actuate drive motor 112 (see, for example, FIGS.1 to 3). As noted above, ECU 160 comprises a printed circuit board (PCB) 162 with a microcontroller (not shown) in communication with a module storing the appropriate software (not shown). The ECU 160 includes the logic to drive power drive unit 100 (via drive motor 112). However, according to some embodiments, the described power drive unit is absent ECU 160 (see, for example, FIG. 9 depicting power drive unit 200, which is similar to power drive unit 100 but instead comprising electrical connector 166 without ECU 160).

[0052] As would be understood by persons skilled in the art, traditional powered automotive closures (such as trunk lids, liftgates and sliding doors) are almost always opened fully with every use and held firmly in place in the fully open position against a fixed end stop (typically using gas struts, springs or latches). However, this is often not the case with powered swinging side doors. Swinging doors are often opened only partially, due to the presence of nearby vehicles or other obstacles. Thus, a user typically interacts with a power door system that is halting and holding the door in a partially open condition. As a result, a power drive unit should be able to hold the door firmly in any position and do so without objectionable noises. An actuator with freeplay in the gear train is undesirable in this regard, since freeplay can lead to clicking noises and uncontrolled motion of the door when coming to a stop or changing direction. However, the gear interface must be designed with some clearance in the gear teeth to allow for manufacturing tolerances and to help ensure operation of the gear train without binding or excess friction.

[0053] With that in mind, the described power drive units incorporate features to reduce or eliminate freeplay in the geartrain comprised of the described worm and helical gears. In particular, the described power drive units introduce an applied force (also referred to herein as a pre-load) to the worm gear 138, which biases the gear teeth of worm gear 138 into the teeth of helical gear 140. This bias tends to reduce and, in some embodiments, eliminate the freeplay between gear teeth while still allowing for the necessary design clearances. The applied force is achieved with an anti-backlash member which may be installed into the actuator after the worm gear is installed.

[0054] Attention is directed to FIGS. 10A to 15B which depict certain features of power drive unit 100, according to non-limiting embodiments. To help ensure meshing engagement between worm gear 138 and helical gear 140, power drive unit 100 may comprise anti-backlash member 168 (generally, anti-backlash member 168, specifically anti-backlash member 168 A depicted in FIGS. 10A, 10B and anti-backlash member 168B depicted in FIGS. 11 to 12B). Anti-backlash member 168 comprises a backlash energy storage member 170 (also referred to herein as a third energy storage member 170) configured to apply the pre-load force (F) to worm gear 138 to push worm gear 138 into meshing engagement with helical gear 140 (FIG.10B). For example, according to some embodiments, backlash energy storage member 170 is biased to compel an abutting member 172 to push against one or more of output shaft 136 and worm gear 138. Any suitable energy storage member is contemplated. According to some embodiments, the backlash energy storage member 170 comprises one or more of a coil spring and an elastomeric member. According to some embodiments, backlash energy storage member 170 comprises a spring. Any suitable abutting member is contemplated. For example, according to some embodiments, abutting member 172 comprises a plunger (as shown in FIGS. 13A, 13B). With the assistance of the anti-backlash member 168, clearance in the meshing between worm gear 138 and helical gear 140 may be reduced. Anti-backlash member 168 may also add friction advantageous for holding the vehicle door in a particular position. It is understood that according to some embodiments power drive unit 100 comprises anti-backlash member 168 but not guide shaft 110. It is also understood that power drive unit 100 may comprise both guide shaft 110 and anti-backlash member 168.

[0055] Anti-backlash member 168 may take a variety of forms and configurations. FIGS. 10A and 10B depict anti-backlash member 168 A, according to a first set of non-limiting embodiments. Anti-backlash member 168A comprises backlash housing 174 configured to fixedly engage with gear housing 104. For example, according to some embodiments, backlash housing 174 is configured to press fit or screw into a corresponding orifice (not shown) of gear housing 104 such that once power drive unit 100 is assembled, the location of anti-backlash member 168 A relative to worm gear 138, helical gear 140 and output shaft 136 is fixed. Anti-backlash member 168A further comprises backlash energy storage member 170 and abutting member 172. As notedabove, backlash energy storage member 170 is biased to compel abutting member 172 into engagement with one or more of worm gear 138 and output shaft 136 to apply the pre-load (F) to worm gear 138. For example, backlash energy storage member 170 is inserted into backlash housing 174 and coupled to abutting member 172 such that the relative position between backlash housing 174 and abutting member 172 is variable based on the extension and compression of backlash energy storage member 170 (since abutting member 172 is movably coupled to backlash housing 174). According to some embodiments, backlash energy storage member 170 may be coupled to backlash housing 174 and abutting member 172 under a preload (see, for example, FIGS. 13A and 13B in which the preload at installation is provided by compressing backlash energy storage member 170 to produce a corresponding preload displacement (PD)). According to some embodiments, backlash energy storage member 170 is configured to have a low spring rate (or equivalent) so that the applied pre-load force (F) does not vary throughout the travel of abutting member 172. The spring rate and preload are selected such that the applied pre-load force (F) is high enough to be able to push the worm gear 138 and helical gear 140 together during low torque conditions but is low enough to allow for some gear separation during high torque conditions.

[0056] According to some embodiments, as shown in FIGS. 10A and 10B, antibacklash member 168A is located along worm gear 138 or output shaft 136 at a location proximate to drive motor 112 such that the preload force (F) is applied proximate drive motor 112 (and to the applied torque) and the reaction force (R) applied by helical gear 140 to worm gear 138 is applied at a location distal to the preload (F) and drive motor 112. According to some embodiments, antibacklash member 168 is configured to apply the pre-load (F) at a location along worm gear 138 distal to drive motor 112 and reaction force (R), as described below in respect of anti-backlash member 168B.

[0057] Attention is directed to FIGS. 11 to 13B which depict anti-backlash member 168B, according to non-limiting embodiments. Anti-backlash member 168B shares many features of anti-backlash feature 168A. However, the backlash housing 174 of anti-backlash member 168B comprises one or more retention clips 176 configured to fixedly engage with gear housing 104 (FIGS. 13A and 13B). For example, according to some embodiments, retention clips 176 areconfigured to fixedly engage with groove 178 of gear housing 104. Retention clips 176 are configured to aid in the installation of anti-backlash member 168B on gear housing 104 such that anti-backlash member 168B can be pre-installed on gear housing 104 with backlash energy storage member 170 under a desired preinstallation preload. In addition, anti-backlash member 168B may comprise at least one O-ring 179 configured to seal the associated orifice of gear housing 104.

[0058] In addition, contrary to anti-backlash member 168 A, anti-backlash member 168B is configured to apply the pre-load (F) to worm gear 138 at a worm gear location 180 distal to first end 139 (FIGS. 12A, 12B). Moving the location of the applied pre-load (F) past the location of the reaction force (R) and further away from the drive motor 112 provides additional stability to the gear arrangement and helps to reduce the force required to deflect the worm gear 138 towards helical gear 140.

[0059] In operation, when torque demand from drive motor 112 is low, backlash energy member 170 pushes worm gear 138 into meshing engagement with helical gear 140, and freeplay is reduced or otherwise eliminated. The resulting friction generated by the preload (F) affects the efficiency of the geartrain, which is expected and accounted for. This friction can be advantageous, as it typically enhances the capability of the power drive unit 100 to hold a vehicle door open without electrical power. As torque demand increases, the gear mesh between worm gear 138 and helical gear 140 generates a separation force (S), which pushes the worm gear 138 and helical gear 140 apart (FIG. 14). A certain amount of separation is advantageous. When separation is within an acceptable range, the worm gear 138 is in an ideal relative position to helical gear 140. At this point, the force provided by backlash energy storage member 170 typically makes up only part of the reaction force (R) on the worm gear 138, so there is typically no added friction from backlash energy storage member 170. As a result, at least according to some embodiments, backlash energy storage member 170 does not affect the maximum output capability of power drive unit 100 (or power drive unit 200). Furthermore, according to some embodiments, there is minimal effect on gear wear, as the highest wear occurs during high torque transmission (at which point backlash energy storage member 170 does not have any effect and worm gear 138 is properly aligned with helical gear 140). Of course, it is understood that separation between worm gear 138 and helical gear 140 must be constrained to avoid insufficient gear meshing (i.e.,insufficient meshing between the gears to transfer torque from the drive motor 112 to the helical gear 140 to turn leadscrew 108). In other words, the optimal worm-to-motor interface is achieved with a coupling that allows for some separation or misalignment.

[0060] According to some embodiments, power drive unit 100 comprises features configured to limit the amount of separation between worm gear 138 and helical gear 140. For example, according to some embodiments, power drive unit 100 further comprises oblong bushing 182 coupled to worm gear 138 and configured to limit movement of worm gear 138 along a first transverse axis (Tl) and to allow some movement of worm gear 138 along a second transverse axis (T2) (FIGS. 15A and 15B, oblong bushing 182 allowing displacement (D) of worm gear 138 along axis T2). Transverse axes Tl and T2 are preferably orthogonal or at right angles to each other. According to some embodiments, oblong bushing 182 is configured to allow some movement of worm gear 138 along the second transverse axis (T2) when the torque output from the drive motor 112 exceeds a limit. For example, according to some embodiments, the torque output from drive motor 112 may exceed a predetermined limit when the vehicle is parked on a steep grade (the torque required to move the door against gravity may exceed the predetermined limit or is otherwise considered “high”). Oblong bushing 182 supports worm gear 138 along the Tl axis while providing the desired clearance along the T2 axis for the preload force (F) to press worm gear 138 towards helical gear 140. According to some embodiments, worm gear 138 is supported in an axial direction (AD) by ball bearing 137. According to some embodiments, oblong bushing 182 is coupled to worm gear 138 proximate the applied pre-load force (F) (FIG. 14).

[0061] According to some embodiments, in addition to backlash energy storage member 170 and oblong bushing 182, the motor coupling and ball bearing 137 allow worm gear 138 to tilt towards helical gear 140 during operation. The motor coupling allows for some misalignment between worm gear 138 (such as worm gear shaft 184 of worm gear 138) and output shaft 136 (FIG. 12B). Furthermore, according to some embodiments, ball bearing 137 is configured to allow for at least some tilting of worm gear 138.

[0062] The described power drive units may comprise additional features to help ensure smooth and quiet operation. According to some embodiments, power drive unit 100 further comprises at least one torque transfer member coupled to at least one of output shaft 136 of thedrive motor 112 and leadscrew 108 (FIGS. 16A to 16D). For example, according to some embodiments, power drive unit 100 comprises a first torque transfer member 186 operatively coupled to output shaft 136 and worm gear 138 (FIGS. 16A and 16B) and / or a second torque transfer member 188 operatively coupled to helical gear 140 and leadscrew 108 (FIGS. 16C and 16D). Torque transfer members 186 and 188 help provide a smooth flexible coupling between the respective components. At least one of torque transfer members 186 and 188 comprises at least two non-resilient members, such as non-resilient members 190 of first torque transfer member 186 and non-resilient members 192 of second torque transfer member 188. Each of non-resilient members 190 (in first torque transfer member 186) and 192 (in second torque member 188) are rotationally coupled to each other, respectively, with a resilient member therebetween (such as resilient member 194 between non-resilient members 190 and resilient member 196 between non-resilient members 192). According to some embodiments, resilient members 194 and 196 comprise an elastomeric material.

[0063] Each of torque transfer members 186, 188 has two operational zones: (1) a Noise, Vibration and Harshness (NVH) zone comprising the respective resilient member, and (2) a Hard-Stop (HS) zone comprising the non-resilient members. Non-resilient members 190, 192 are fixedly coupled to the respective output shaft 136 / worm gear 138 or helical gear 140 / leadscrew 108 with the respective resilient member 194, 196 rotationally sandwiched therebetween. During normal operation (e.g., normal operating torque loads between the drive motor output shaft 136 and the worm gear 138 or between the helical gear 140 and the leadscrew 108), the respective resilient member flexes to absorb some of the mis-match between the respective turning members (output shaft 136 / worm gear 138 or helical gear 140 / leadscrew 108). During high torsional loads, the non-resilient members of the HS zone shift relative to each other, compressing the respective resilient member to the extent that the respective two non-resilient members abut each other providing a “hard stop”. This “hard stop” helps to limit the maximum compression or deformation of the respective resilient member during rotational coupling which may allow for use of a lower durometer elastomer for the respective resilient member. As a result, torque transfer members 186, 188 may better handle misalignment between the respective torsional interfaces (e.g., the interface between the output shaft 136 / worm gear 138 or the interface between helical gear140 / leadscrew 108) and improve sound quality while reducing shock loads. Any suitable material or combination of suitable materials for the non-resilient members 190, 192 and the resilient members 194, 196 is contemplated. For example, resilient members 194, 196 may be fabricated from an elastomeric material, such as rubber.

[0064] It will also be understood that for the purposes of this application, "at least one of X, Y, and Z" or "one or more of X, Y, and Z" language can be construed as X only, Y only, Z only, or any combination of two or more items X, Y, and Z (e.g., XYZ, XYY, YZ, ZZ, XX, XY).

[0065] In the present application, components may be described as being "configured to" or "enabled to" perform one or more functions. Generally, it is understood that a component that is configured to or enabled to perform a function is configured to or enabled to perform the function, or is suitable for performing the function, or is adapted to perform the function, or is operable to perform the function, or is otherwise capable of performing the function.

[0066] Additionally, components in the present application may be described as being "operatively connected to", "operatively coupled to", and the like, to other components. It is understood that such components are connected or coupled to each other in a manner to perform a certain function. It is also understood that "connections", "coupling" and the like, as recited in the present application include direct and indirect connections between components.

[0067] References in the application to "one embodiment", "an embodiment", "an implementation", "a variant", etc., indicate that the embodiment, implementation or variant described may include a particular aspect, feature, structure, or characteristic, but not every embodiment, implementation or variant necessarily includes that aspect, feature, structure, or characteristic. Moreover, such phrases may, but do not necessarily, refer to the same embodiment referred to in other portions of the specification. Further, when a particular aspect, feature, structure, or characteristic is described in connection with an embodiment, it is within the knowledge of one skilled in the art to affect or connect such module, aspect, feature, structure, or characteristic with other embodiments, whether or not explicitly described. In other words, any module, element or feature may be combined with any other element or feature in different embodiments, unless there is an obvious or inherent incompatibility, or it is specifically excluded.

[0068] It is further noted that the claims may be drafted to exclude any optional element. As such, this statement is intended to serve as antecedent basis for the use of exclusive terminology, such as "solely", "only", and the like, in connection with the recitation of claim elements or use of a "negative" limitation. The terms "preferably", "preferred", "prefer", "optionally", "may", and similar terms are used to indicate that an item, condition or step being referred to is an optional (not required) feature of the invention.

[0069] The singular forms "a", "an", and "the" include the plural reference unless the context clearly dictates otherwise. The term "and / or" means any one of the items, any combination of the items, or all of the items with which this term is associated. The phrase "one or more" is readily understood by one of skill in the art, particularly when read in context of its usage.

[0070] The term "about" can refer to a variation of± 5%, ± 10%. ± 20%, or± 25% of the value specified. For example, "about 50" percent can in some embodiments carry a variation from 45 to 55 percent. For integer ranges, the term "about" can include one or two integers greater than and / or less than a recited integer at each end of the range. Unless indicated otherwise herein, the term "about" is intended to include values and ranges proximate to the recited range that are equivalent in terms of the functionality of the composition, or the embodiment.

[0071] As will be understood by one skilled in the art, for any and all purposes, particularly in terms of providing a written description, all ranges recited herein also encompass any and all possible sub-ranges and combinations of sub-ranges thereof, as well as the individual values making up the range, particularly integer values. A recited range includes each specific value, integer, decimal, or identity within the range. Any listed range can be easily recognized as sufficiently describing and enabling the same range being broken down into at least equal halves, thirds, quarters, fifths, or tenths. As a non-limiting example, each range discussed herein can be readily broken down into a lower third, middle third and upper third, etc.

[0072] As will also be understood by one skilled in the art, all language such as "up to", "at least", "greater than", "less than", "more than", "or more", and the like, include the number recited and such terms refer to ranges that can be subsequently broken down into sub-ranges as discussed above. In the same manner, all ratios recited herein also include all sub-ratios falling within the broader ratio.

[0073] Persons skilled in the art will appreciate that there are yet more alternative implementations and modifications possible, and that the above examples are only illustrations of one or more implementations. The scope, therefore, is only to be limited by the claims appended hereto.

Claims

CLAIMSWhat is claimed is:

1. A power drive unit for opening and closing a vehicle door comprising:a bracket configured to couple to one of a vehicle body and the vehicle door;a gear housing configured to couple to the other one of the vehicle body and the vehicle door;a link arm operatively coupled to the bracket at a first end and pivotally coupled to a carrier at a second end distal to the first end;a leadscrew and a guide shaft coupled to the gear housing spaced apart from each other; anda drive motor operatively coupled to the leadscrew;wherein the carrier is operatively coupled to the guide shaft and to the leadscrew, the carrier being configured to travel along the guide shaft and the leadscrew in a door open direction and in a door closed direction opposite the door open direction as the leadscrew rotates in a nut fixed in relation to the carrier; andwhereinwhen the drive motor is driven in a first direction, the carrier travels in the door open direction, andwhen the drive motor is driven in a second direction opposite the first direction, the carrier travels in the door closed direction.

2. The power drive unit of claim 1, further comprising:an anti-rotation member coupled to the carrier or incorporated into at least one housing face proximate the leadscrew, the anti-rotation member configured to engage the at least one housing face or at least one carrier face to resist torsional displacement of the leadscrew during operation of the drive motor.

3. The power drive unit of claim 2, wherein the at least one housing face is an interior face of one or more of the gear housing and a carrier housing.

4. The power drive unit of either claim 2 or claim 3, wherein the anti-rotation member comprises:a first energy storage member configured to resiliently engage the at least one housing face or to resiliently engage the at least one carrier face.

5. The power drive unit of claim 4, wherein the first energy storage member comprises an S- shaped spring.

6. The power drive unit according to any one of claims 2 to 5, wherein the anti-rotation member further comprises at least one resilient bumper.

7. The power drive unit of either claim 2 or claim 3, wherein the anti-rotation member comprises:a cam-shaped member configured to abut the at least one housing face when in a first orientation; anda second energy storage member coupled to the cam-shaped member and configured to resiliently position the cam-shaped member to the first orientation.

8. The power drive unit of claim 7, wherein the second energy storage member comprises a leaf spring which resiliently abuts a pre-load protrusion of the carrier.

9. The power drive unit according to any one of claims 1 to 8, wherein an output shaft of the drive motor is coupled to a worm gear configured to mesh with a helical gear, the helical gear being operatively coupled to the leadscrew.

10. The power drive unit of claim 9, further comprising an anti-backlash member having a third energy storage member configured to apply a pre-load to the worm gear to push the worm gear into meshing engagement with the helical gear.

11. The power drive unit of claim 10, wherein the anti-backlash member is configured to apply the pre-load at a location along the worm gear distal to the drive motor.

12. The power drive unit of either claim 9 or claim 10 further comprising an oblong bushing coupled to the worm gear, the oblong bushing being configured to support the worm gear such that movement along a first transverse axis of the worm gear is more limited than movement along a second transverse axis of the worm gear.

13. The power drive unit according to any one of claims 10 to 12, wherein the third energy storage member comprises a spring, preferably a coil spring, or an elastomeric member.

14. The power drive unit according to any one of claims 9 to 13, further comprising a first torque transfer member operatively coupled to the output shaft and the worm gear.

15. The power drive unit according to any one of claims 9 to 14, further comprising a second torque transfer member operatively coupled to the helical gear and the leadscrew.

16. The power drive unit of either claim 14 or claim 15, wherein at least one of the first torque transfer member and the second torque transfer member comprises two non-resilient members rotationally coupled to each other with a resilient member therebetween.

17. The power drive unit of claim 16, wherein the resilient member comprises an elastomeric material.

18. The power drive unit according to any one of claims 1 to 17, further comprising an electronic control unit configured to actuate the drive motor.

19. The power drive unit according to any one of claims 1 to 18, further comprising at least one bushing positioned between the guide shaft and the carrier.

20. A power drive unit for opening and closing a vehicle door comprising:a bracket configured to couple to one of a vehicle body and the vehicle door;a gear housing configured to couple to the other one of the vehicle body and the vehicle door;a link arm operatively coupled to the bracket at a first end and pivotally coupled to a carrier at a second end distal to the first end;a leadscrew coupled to the gear housing;a drive motor operatively coupled to the leadscrew and having an output shaft operatively coupled to a worm gear, the worm gear being configured to mesh with a helical gear operatively coupled to the leadscrew; andan anti-backlash member having a backlash energy storage member configured to apply a pre-load force to the worm gear to push the worm gear into meshing engagement with the helical gear;wherein the carrier is operatively coupled to the leadscrew, the earner being configured to travel along the leadscrew in a door open direction and in a door closed direction opposite the door open direction as the leadscrew rotates in a nut fixed in relation to the carrier; andwhereinwhen the drive motor is driven in a first direction, the carrier travels in the door open direction, andwhen the drive motor is driven in a second direction opposite the first direction, the carrier travels in the door closed direction.

21. The power drive unit of claim 20, wherein the output shaft is operatively coupled to a first end of the worm gear via a ball bearing and the anti-backlash member is configured to apply the preload to the worm gear at a worm gear location distal to the first end of the worm gear.

22. The power drive unit of either claim 20 or claim 21 further comprising an oblong bushing coupled to the worm gear and configured to limit movement of the worm gear along a first transverse axis and to allow some movement of the worm gear along a second transverse axis.

23. The power drive unit of claim 22, wherein the oblong bushing is configured to allow some movement of the worm gear along the second transverse axis when torque output from the drive motor exceeds a limit.

24. The power drive unit of either claim 22 or claim 23, wherein the oblong bushing is coupled to the worm gear proximate the applied pre-load force.

25. The power drive unit according to any one of claims 20 to 24, wherein the anti-backlash member comprises:a backlash housing configured to fixedly engage with the gear housing; and an abutting member moveably coupled to the backlash housing via the backlash energy storage member, the backlash energy storage member being biased to compel the abutting member into engagement with one or more of the worm gear and the output shaft to apply the pre-load to the worm gear.

26. The power drive unit of claim 25, wherein the backlash housing comprises one or more retention clips configured to fixedly engage with the gear housing.

27. The power drive unit of either claim 25 or claim 26, wherein the abutting member comprises a plunger.

28. The power drive unit according to any one of claims 20 to 27, wherein the backlash energy storage member comprises one or more of a spring and an elastomeric member.

29. The power drive unit of claim 28, wherein the spring comprises a coil spring.

30. The power drive unit according to any one of claims 20 to 29, further comprising a first torque transfer member operatively coupled to the output shaft and the worm gear.

31. The power drive unit according to any one of claims 20 to 30, further comprising a second torque transfer member operatively coupled to the helical gear and the leadscrew.

32. The power drive unit of either claim 30 or claim 31 , wherein at least one of the first torque transfer member and the second torque transfer member comprises two non-resilient members rotationally coupled to each other with a resilient member therebetween.

33. The power drive unit of claim 32, wherein the resilient member comprises an elastomeric material.

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