Lift assembly

Abstract

A lift assembly includes a base, a platform moveable relative to the base between raised and lowered positions, and a scissor mechanism to move the platform relative to the base. The lift assembly also includes a drive mechanism including a mount block, a plurality of electric motors arranged in series to define an initial electric motor, one or more intermediate electric motors, and a final electric motor, and a plurality of gears each mounted to one of the electric motors. The drive mechanism also includes an output shaft spaced from the electric motors and coupled to the mount block, an output gear rotationally coupled to the output shaft and driven by the gear mounted to the final electric motor to receive a combined rotational torque from the series of electric motors, and an output belt wound about the output shaft upon rotation of the output gear.

Description

LIFT ASSEMBLYBACKGROUND OF THE INVENTION1. Field of the Invention

[0001] The invention relates generally to a lift assembly.2. Description of the Related Art

[0002] Lift assemblies commonly include a base, a platform moveable relative to the base, a first pair of scissor arms, and a second pair of scissor arms. The first pair of scissor arms and the second pair of scissor arms typically pivot to permit the platform to move. Movement of the scissor arms, and thus the platform, is typically effectuated by a drive mechanism. Conventionally, these drive mechanisms are fixed relative to the base and include electric motors which output rotational torque to an output shaft, and an output belt is wound about the output shaft upon rotation of the output shaft. Typically, these output shafts are physically spaced from the electric motors through a series of intervening gearing. The intervening gearing may assist in positioning the output shaft above the remainder of the drive mechanism to permit the output belt to be wound about the output shaft without physical interferences with the drive mechanism. However, the intervening gearing also causes physical interferences with the platform as the platform is moved to the lowered position, thus preventing the platform from being lowered to a sufficient height for many applications.

[0003] As such, there remains a need for an improved lift assembly.SUMMARY OF THE INVENTION AND ADVANTAGES

[0004] The present invention provides a lift assembly including a base and a platform moveable relative to the base between a raised position and a lowered position. Thelift assembly also includes a scissor mechanism coupled to the base and to the platform to move the platform relative to the base. The lift assembly further includes a drive mechanism coupled to the base. The drive mechanism includes a mount block extending along an axis and a plurality of electric motors supported by the mount block. The electric motors are arranged in series along the axis to define an initial electric motor, one or more intermediate electric motors, and a final electric motor. The drive mechanism also includes a plurality of gears each mounted to one of the electric motors, an output shaft spaced from the electric motors and coupled to the mount block, and an output gear rotationally coupled to the output shaft and driven by the gear mounted to the final electric motor to receive a combined rotational torque from the series of electric motors. The drive mechanism further includes an output belt wound about the output shaft upon rotation of the output gear.

[0005] Accordingly, the output gear driven by the gear mounted to the final electric motor and the output shaft rotationally coupled to the output gear permits the output belt to be wound about the output shaft without resulting in physical interferences with the scissor mechanism or the platform, particularly when the platform is in the lowered position. As such, the platform is permitted to achieve a relatively close proximity to the base. The platform achieving a relatively close proximity to the base enables a relatively low overall height of the lift assembly when the platform is in the lowered position and thus permits the lift assembly to fit under objects with relatively tight clearances to the ground to lift these objects with the platform to the raised position.BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Other advantages of the present invention will be readily appreciated, as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings.

[0007] Figure 1 is a perspective view of a lift assembly having a platform in a raised position.

[0008] Figure 2 is a perspective view of the lift assembly of Figure 1 , with the platform in a lowered position.

[0009] Figure 3 is a perspective view of a lift assembly having the platform in the raised position.

[0010] Figure 4 is a perspective view of the lift assembly of Figure 3, with the platform in the lowered position.

[0011] Figure 5 is a perspective view of the lift assembly having a skirt and the platform in the raised position.

[0012] Figure 6 is a perspective view of the lift assembly of Figure 5, with the platform in the lowered position.

[0013] Figure 7 is a side view partially in cross-section of the lift assembly of Figures 1 -6.

[0014] Figure 8 is a rear view of the lift assembly of Figures 1-7.

[0015] Figure 9 is a rear view partially in cross-section of the lift assembly ofFigure 8.

[0016] Figure 10 is an exploded view of the lift assembly, with the lift assembly including a guide roller.

[0017] Figure 11 is an exploded view of the lift assembly, with the lift assembly including the guide roller.

[0018] Figure 12 is an exploded view partially in cross-section of the lift assembly of Figure 8.

[0019] Figure 13 is a perspective view of a drive mechanism for the lift assembly of Figures 1-12.

[0020] Figure 14 is a perspective view of another embodiment of a lift assembly having the platform in the raised position.

[0021] Figure 15 is a perspective view of the lift assembly of Figure 14 having the platform in the lowered position.

[0022] Figure 16 is a perspective view of the lift assembly having a skirt and the platform in the raised position.

[0023] Figure 17 is a perspective view of the lift assembly of Figure 16, with the platform in the lowered position.

[0024] Figure 18 is a perspective rear view of the lift assembly of Figures 14- 17.

[0025] Figure 19 is a side view partially in cross-section of the lift assembly of Figures 14-18.

[0026] Figure 20 is a rear view of the lift assembly of Figures 14-19.

[0027] Figure 21 is an exploded view of the lift assembly of Figures 14-20.

[0028] Figure 22 is a side view of the lift assembly of Figures 14-21, with the platform in the lowered position.

[0029] Figure 23 is an exploded view of the lift assembly of Figure 22.

[0030] Figure 24 is a perspective view of the drive mechanism for the lift assembly of Figures 14-23.

[0031] Figure 25 is a perspective view of the drive mechanism of Figure 24.

[0032] Figure 26 is a front view partially in cross-section of the drive mechanism of Figures 24 and 25.

[0033] FIG. 27 is a perspective view of a planetary gearset of the lift assembly;

[0034] FIG. 28 is another perspective view of the planetary gearset of the lift assembly; and

[0035] FIG. 29 is another perspective view of the planetary gearset of the lift assembly.DETAILED DESCRIPTION OF THE INVENTION

[0036] With reference to the Figures, wherein like numerals indicate like parts throughout the several views, a lift assembly 100 includes a base 102 and a platform 104 moveable relative to the base 102 between a raised position, as shown in Figures 1, 3, 5, 7-9, 14, 16, and 18-20, and a lowered position, as shown in Figures 2, 4, 6, 15, 17, 22, and 23. The lift assembly 100 also includes a scissor mechanism 106 coupled to the base 102 and to the platform 104 to move the platform 104 relative to the base 102. The lift assembly 100 further includes a drive mechanism 108 coupled to the base 102. The drive mechanism 108 includes a mount block 110 extending along an axis Al and a plurality of electric motors 112 supported by the mount block 110. The electric motors 112 are arranged in series along the axis Al to define an initial electric motor 1 14, one or more intermediate electric motors 1 16, and a final electric motor 118. The drive mechanism 108 also includes a plurality of gears 120 each mounted to one of the electric motors 112, an output shaft 122 spaced from the electric motors 1 12 and coupled to the mount block 110, and an output gear 124 rotationally coupled to the output shaft 122 and driven by the gear 120 mounted to the final electric motor 118 to receive a combined rotational torque from the series of electric motors 112. The drive mechanism 108 further includes an output belt 126 wound about the output shaft 122 upon rotation of the output gear 124.

[0037] Accordingly, the output gear 124 driven by the gear 120 mounted to the final electric motor 118 and the output shaft 122 rotationally coupled to the output gear 124 permits the output belt 126 to be wound about the output shaft 122 without resulting in physical interferences with the scissor mechanism 106 or the platform 104, particularly when theplatform 104 is in the lowered position. As such, the platform 104 is permitted to achieve a relatively close proximity to the base 102. The platform 104 achieving a relatively close proximity to the base 102 enables a relatively low overall height of the lift assembly 100 when the platform is in the lowered position and thus permits the lift assembly 100 to fit under objects with relatively tight clearances to the ground and lift these objects with the platform 104 to the raised position.

[0038] As discussed herein, the output gear 124 is rotationally coupled to the output shaft 122. More specifically, the output gear 124 may be rotationally fixed to the output shaft 122. Although not required, it is to be appreciated that the output gear 124 may be fixed to the output shaft 122. Moreover, the output gear 124 may rotate about a rotational axis, and the output shaft 122 may be coaxial with the rotational axis of the output gear 124. Said differently, the output shaft 122 may extend along an output shaft axis, and the output gear 124 may be rotatable about the output shaft axis. In a non-limiting example, the output gear 124 may define a bore, and the output shaft 122 may be disposed at least partially in the bore of the output gear 124. In one embodiment, the output shaft 122 and the output gear 124 are keyed or splined together such that the output shaft 122 and the output gear 124 are rotationally fixed to one another. In another embodiment, the output shaft 122 and the output gear 124 are welded together such that the output shaft 122 and the output gear 124 are rotationally fixed to one another. Moreover, the output shaft 122 and the output gear 124 may be integral with one another, such as formed integrally with one another or formed separately and later joined to become integral.

[0039] The plurality of electric motors 112 arranged in series permits the rotational torque from the gears 120 to be combined. The combined rotational torque from the gears 120 of the series of electric motors 112 is then transferred from the gear 120 of the final electric motor 118 to drive the output gear 124. The series arrangement of the plurality ofelectric motors 112 lowers the profile of the drive mechanism 108 while still being capable of generating significant power due to the rotational torque from the gears 120 being combined.

[0040] The series of gears 120 may be in meshed relation with one another, as shown in Figures 19, 24, and 25. In other words, each of the plurality of gears 120 may be in contact with at least one adjacent gear 120. Moreover, the gear 120 of the final electric motor 118 may be in meshed relation with the output gear 124. Moreover, in some embodiments, at least one of the gears 120 mounted to at least one of the intermediate electric motors 116 is an idler gear 128 not directly driven by an electric motor 112. The idler gear 128 may serve instead to transfer torque between adjacent gears, while maintaining space near the drive mechanism 108 which is not occupied by an electric motor 112.

[0041] The lift assembly 100 may further include a tensioner pulley 130 supported by the base 102 and contactable with the output belt 126 when the platform is in the lowered position. The tensioner pulley 130 may include a bracket 132 fixed to the base 102 and a pulley 134, roller 134, or other rotatable component rotatable about the bracket 132. The tensioner pulley 130 prevents the output belt 126 from contacting the drive mechanism 108 and / or other components of the lift assembly 100 while the platform 104 is in the lowered position. The tensioner pulley 130 also provides a vertical vector force on the output belt 126 as the platform 104 is moved from the lowered position to the raised position, thus decreasing the amount of combined rotational torque needed to be provided by the series of electric motors 112 to successfully move the platform 104 to the raised position. Moreover, although not required, the tensioner pulley 130 may be positioned adjacent to the idler gear 128. More specifically, the tensioner pulley 130 may be positioned in the space maintained near the drive mechanism 108 which is adjacent to the idler gear 128 and not occupied by an electric motor 112.

[0042] The plurality of electric motors 112 may each be stepper motors. The plurality of electric motors 112 may each include a housing, a stator disposed within the housing, and a rotor disposed within the stator. In one embodiment, each electric motor 112 is fixed to the mount block 110. The drive mechanism 108 may further include a plurality of motor shafts rotationally fixed to the rotors of the electric motors 112 and rotationally fixed to one of the plurality of gears 120. In a non- limiting example, each motor shaft may be keyed, or splined, to one of the plurality of gears 120 to rotationally fix the motor shaft to the gear 120. In other non-limiting examples, each motor shaft may be welded, brazed, soldered, or otherwise physically joined with one of the plurality of gears 120, each motor shaft may be integral with one of the plurality of gears 120, or each motor shaft may be formed integrally with one of the plurality of gears 120 such as but not limited to by casting. The motor shaft associated with the electric motor 112 may extend through a bore defined by the mount block 110. As such, the mount block 110 may define a plurality of bores through which a plurality of motor shafts may extend. Moreover, the drive mechanism 108 may include a bearing disposed in the bore for supporting rotation of the motor shaft. The bearing may be a ball bearing, a roller bearing such as but not limited to a needle bearing, or a plain bearing, among other possibilities. It is to be appreciated that the drive mechanism 108 may include a plurality of bearings, each disposed in one bore defined by the mount block 110.

[0043] In another embodiment, the lift assembly 100 may further include a plurality of transmissions 136 each disposed between one of the series of electric motors 112 and the mount block 110. Each transmission 136 is configured to modulate torque provided to the gears 120 from the electric motors 112. As described further below, each of the plurality of transmissions 136 may be further defined as a planetary gearset 230. As also described further below, each of the plurality of transmissions 136 may be further defined as a plurality of planetary gearsets 230.

[0044] More specifically, each electric motor 112 may be fixed to a transmission 136, and each transmission 136 may be fixed to the mount block 110. The plurality of motor shafts may be rotationally fixed to the transmission, and the transmission may be rotationally fixed to a transmission shaft which is rotationally fixed to one of the plurality of gears 120. In a non- limiting example, each transmission shaft may be keyed, or splined, to one of the plurality of gears 120 to rotationally fix the transmission shaft to the gear 120. In other non-limiting examples, each transmission shaft may be welded, brazed, soldered, or otherwise physically joined with one of the plurality of gears 120, each transmission shaft may be integral with one of the plurality of gears 120, or each transmission shaft may be formed integrally with one of the plurality of gears 120 such as but not limited to by casting. The transmission shaft associated with the electric motor 112 may extend through the bore defined by the mount block 110. As such, the mount block 110 may define a plurality of bores through which a plurality of motors shafts may extend. Moreover, the drive mechanism 108 may include a bearing disposed in the bore for supporting rotation of the transmission shaft. The bearing may be a ball bearing, a roller bearing such as but not limited to a needle bearing, or a plain bearing, among other possibilities. It is to be appreciated that the drive mechanism 108 may include a plurality of bearings, each disposed in one bore defined by the mount block 110.

[0045] Each motor shaft of each electric motor 112 may rotate at a relatively high rotational speed. Each transmission 136 reduces the rotational speed of the motor shaft and increases the relative torque generated by the transmission shaft. In this way, each transmission 136 assists in increasing the torque exerted on the plurality of gears 120. Although not required, the transmission 136 may include at least one planetary gearset 230. Each planetary gearset 230 may include any chosen from a sun gear, two or more planet gears (such as three planet gears), a ring gear, and a carrier gear. Although not required, the transmission 136 may include a first planetary gearset 232, may include a second planetary gearset 234, andmay include a third planetary gearset 236. It is to be appreciated that the transmission 136 may include any number of planetary gearsets 230. Each planetary gearset 230 reduces the rotational speed and increases the torque generated.

[0046] Although not required, the ring gear may be common among the planetary gearsets 230. More specifically, the first planetary gearset 232, the second planetary gearset 234, and the third planetary gearset 234 may include a common ring gear. The common ring gear may be incorporated into a housing for the planetary gearsets 230, as shown in Figures 27-29. The common ring gear may be fixed relative to the mount block 110. In other words, the sun gear(s) and / or planetary gear(s) may rotate within the common ring gear fixed while the common ring gear remains stationary (e.g., fixed to the mount block 110). It is also to be appreciated that each successive planetary gearset 230 further reduces the rotational speed of the motor shaft and increases the relative torque generated by the transmission shaft. Although the planetary gearset 230 as shown in Figures 27-29 includes the first planetary gearset 232, the second planetary gearset 234, and the third planetary gearset 236, and more particularly includes the common ring gear, it is to be appreciated that other arrangements of planetary gearsets 230 may be used in accordance with the present invention and are contemplated herein.

[0047] Contact between adjacent gears 120 creates friction and back-drive between the gears 120 and / or the transmissions 136 and / or the electric motors 112. As such, no control system need be used a brake, thus simplifying any control system present (e.g., brake synchronization among electric motors 112) and lowering the cost of the drive mechanism 108. However, a control system to be used a brake may be included nonetheless as a redundant safety precaution.

[0048] The plurality of electric motors 112 and the gears 120 may be each rotatable about a rotational axis. The rotational axes of the series of electric motors 112 may be aligned along a common plane. Moreover, the output gear 124 may be rotatable about arotational axis, and the rotational axis may be aligned along the common plane. However, it is to be appreciated that the rotational axis of the output gear 124 may be offset from the common plane.

[0049] The mount block 110 may be further defined as a first mount block 110, the plurality of electric motors 112 may be further defined as a first plurality of electric motors 112 defining a first initial electric motor 114, one or more first intermediate electric motors 116, and a first final electric motor 118. The drive mechanism 108 may further include a second mount block 138 extending along a second axis A2. The second axis A2 may extend parallel to the first axis Al. The drive mechanism 108 may also include a second plurality of electric motors 140 supported by the second mount block 138. The second plurality of electric motors 140 are arranged in series along the second axis A2 to define a second initial electric motor 142, one or more second intermediate electric motors 144, and a second final electric motor 146. The second mount block 138 may include all or some of the same characteristics of the first mount block 1 10, such as defining a plurality of bores and including a plurality of bearings each disposed in one bore of the second mount block 138.

[0050] The plurality of gears 120, the first plurality of electric motors 1 12, and the second plurality of electric motors 140 may be arranged in a plurality of drive assemblies 148. Each drive mechanism 108 includes one of the first plurality of electric motors 112, one of the gears 120, and one of the second plurality of electric motors 140. The drive mechanism 108 may include at least three drive assemblies 148, at least four drive assemblies 148, at least five drive assemblies 148, at least six drive assemblies 148, at least seven drive assemblies 148, at least eight drive assemblies 148, at least nine drive assemblies 148, at least ten drive assemblies 148, or any other larger number of drive assemblies 148.

[0051] Moreover, the gear 120 of the first initial electric motor 114 may also be mounted to the second initial electric motor 142. In other words, there may be an initial driveassembly. Additionally, the gear 120 of the first final electric motor 118 may also be mounted to the second final electric motor 146. Thus, there may be a final drive assembly. The gear 120 of each of the one or more first intermediate electric motors 116 may also be mounted to one of the one or more second intermediate electric motors 144. As such, there may be one or more intermediate drive assemblies.

[0052] The first mount block 110 may be disposed between the first plurality of electric motors 112 and the gears 120, and the second mount block 138 may be disposed between the second plurality of electric motors 140 and the gears 120. The first plurality of electric motors 112 and the second plurality of electric motors 140 may be disposed opposite one another and configured to rotate in opposite rotational directions relative to one another. In other words, the first plurality of electric motors 112 may be configured to rotate clockwise and the second plurality of electric motors 140 may be configured to rotate counterclockwise, or the first plurality of electric motors 112 may be configured to rotate counterclockwise and the second plurality of electric motors 140 may be configured to rotate clockwise. In this manner, the total rotational torque imparted upon the gears 120 is additive of the torque generated by the first plurality of electric motors 112 and the torque generated by the second plurality of electric motors 140.

[0053] The one of the first plurality of electric motors 112 and the one of the second plurality of electric motors 56 in one drive mechanism 108 may be considered to be in a parallel torque arrangement. Moreover, each drive mechanism 108 may be arranged in a series torque arrangement. The electric motors 112, 140 of the drive assemblies 148 arranged in series with one another need not rotate at the same rotational speed. It is contemplated that the electric motors 112, 140 of the drive assemblies 148 arranged in series with one another may rotate at different rotational speeds. Additionally, the first plurality of electric motors 112 and the second plurality of electric motors 140 may be powered by alternating current or directcurrent. Sources of electrical energy (e.g., wires) to power the first plurality of electric motors112 and the second plurality of electric motors 140 may be in electrical communication with a power source.

[0054] As mentioned herein, the output gear 124 driven by the gear 120 of the final electric motor(s) 118, 146 receives the combined rotational torque from the gears 120 of the series of electric motors 112, 140. As such, the output gear 124 may be configured to receive rotational torque from the plurality of gears 120. Although not required, the rotational torque provided to the output gear 124 may be exclusively provided by the gear 120 of the final electric motor 118. Moreover, each of the gears 120 may be sized such that a gear reduction is not established between the gears 120 of the series of electric motors 112, 140. Moreover, the output gear 124 may be sized such that a gear reduction is not established between the gear 120 of the final electric motor(s) 118, 146 and the output gear 124.

[0055] The drive mechanism 108 may be configured to produce high torque at low rotations per minute (RPM) of the output shaft 122 and / or the gears 120. In a non-limiting example, the drive mechanism 108 may exert sufficient torque to lift thousands of pounds on the platform 104 between the lowered position and the raised position. The first plurality of electric motors 112, the second plurality of electric motors 140, and the gears 120 may be together configured to rotate the output shaft 122 between 1 RPM and 50 RPM, between 5 RPM and 40 RPM, between 10 RPM and 30 RPM, between 10 RPM and 20 RPM, and may be approximately 15 RPM. Such low rotations per minute of the output shaft 122 prevents binding of the gears 120, which may otherwise be expected from such an arrangement.

[0056] Moreover, the electric motors 112 arranged in spaced relation to one another along the axis Al do not present any electric or magnetic field concerns that would prevent the electric motors 112 from successfully operating. More specifically, because the relative energy usage of each electric motor 112 is relatively low, the total flux generated bythe electric motor 112 is insufficient to cause malfunction of adjacent electric motor(s) 112.Therefore, the electric motors 112 may be arranged in spaced relation to one another relatively closely along the axis Al. For example, a gap may be defined between adjacent electric motors 112 along the axis Al. The gap may be between 0.1 inches and 3 inches, may be between 0.25 inches and 2 inches, may be between 0.25 inches and 1.5 inches, may be between 0.25 inches and 1.25 inches, and may be between 0.25 inches and 1 inch.

[0057] Although not required, the output shaft 122 may have a lip 150 extending circumferentially about a distal end 152 of the output shaft 122 to retain the output belt 126 to the output shaft 122. The lip 150 may be integral with the output shaft 122. However, the lip 150 may be a separate component or portion of a separate component. In a non-limiting example, a spool may be disposed about the output shaft 122 and rotationally fixed to the output shaft 122, and the spool may have the lip 150. The lip 150 assists in preventing the output belt 126 from becoming misaligned or otherwise disengaged from the output shaft 122.

[0058] In one embodiment, as shown in Figures 9 and 13, the lift assembly 100 includes a bearing 154 supported by the base, and the distal end 152 of the output shaft 122 is supported by the bearing 154. Although not required, the bearing 154 may be further defined as a pillow block. As shown in Figures 9 and 13, the bearing 154 is depicted as one particular construction of the pillow block. However, it is to be appreciated that the bearing 154 may be arranged through other constructions, such as other constructions of pillow blocks.

[0059] In another embodiment, as shown in Figures 21-25, the output shaft 122 forms a cantilever with the distal end 152 of the output shaft 122 free-floating. It is to be appreciated that the proximal end 156 of the output shaft 122 may be supported by the mount block 110. However, in the embodiments with both the first and second mount blocks 110, 138 and the first and second series of electric motors 112, 140, it is to be appreciated that the outputshaft 122 may be supported by both the first and second mount blocks 110, 138 and extend such that both distal ends of the output shaft 122 are free-floating. In other words, the output shaft 122 may form two cantilevers on opposing sides of the drive mechanism 108.

[0060] The scissor mechanism 106 may include a first arm 158, a second arm 160, a third arm 162, and a fourth arm 164 each supported by the base 102 and extending toward the platform 104. The first arm 158 and the second arm 160 may be pivotable relative to one another to define a first pair of scissor arms 166 to assist the platform in moving between the raised position and the lowered position. The third arm 162 and the fourth arm 164 may be pivotable relative to one another to define a second pair of scissor arms 168 to assist the platform in moving between the raised position and the lowered position. The drive mechanism 108 may be disposed between the first and second pairs of scissor arms 166, 168.

[0061] More specifically, the first arm 158 may extend between the base 102 and the platform 104, the second arm 160 may extend between the base 102 and the platform 104, the third arm 162 may extend between the base 102 and the platform 104, and the fourth arm 164 may extend between the base 102 and the platform 104. However, it is to be appreciated that the lift assembly 100 may include a fifth arm pivotably coupled to the first arm 158, a sixth arm pivotably coupled to the second arm 160, a seventh arm pivotably coupled to the third arm 162, and an eighth arm pivotably coupled to the fourth arm 164. The fifth arm, the sixth arm, the seventh arm, and the eighth arm may extend to the platform 104. However, there may even be a ninth arm, a tenth arm, an eleventh arm, and a twelfth arm pivotably coupled to the fifth arm, the sixth arm, the seventh arm, and the eighth arm, respectively, which also extend to the platform 104. The fifth arm, the sixth arm, the seventh arm, the eighth arm, as well as the ninth arm, the tenth arm, the eleventh arm, and the twelfth arm, serve to extend a vertical distance that the platform 104 may be moved to relative to the base 102.

[0062] The first arm 158 may be rotationally fixed to the platform 14 and may be moveable relative to the base 102. In a non-limiting example, the first arm 158 may include a first wheel 170 in contact with the base 102 to permit the first arm 158 to move relative to the base 102. The second arm 160 may be rotationally fixed to the base 102 and may be moveable relative to the platform 104. In a non-limiting example, the second arm 160 may include a second wheel 172 in contact with the platform 104 to permit the second arm 160 to move relative to the platform 104. The third arm 162 may be rotationally fixed to the base 102 and may be moveable relative to the platform 104. In a non-limiting example, the third arm 162 may include a third wheel 174 in contact with the platform 104 to permit the third arm 162 to move relative to the platform 104. The fourth arm 164 may be rotationally fixed to the platform 104 and may be moveable relative to the base 102. In a non-limiting example, the fourth arm 164 may include a fourth wheel 176 in contact with the base 102 to permit the fourth arm 164 to move relative to the base 102.

[0063] The lift assembly 100 may further include a second shaft 178 coupled to the second arm 160 and the third arm 162. The second shaft 178 may define a groove 180, and the output belt 126 may be disposed at least partially in the groove 180 to align the output belt 126 upon winding the output belt 126 about the second shaft 178. It is to be appreciated that the output belt 126 need not be wound completely about the second shaft 178 in order for the groove 180 to align the output belt 126. In other words, the groove 180 may align the output belt 126 when the output belt 126 is only partially wound about the second shaft 178.

[0064] The second shaft 178 may include a core shaft 182 extending transverse to the second arm 160 and the third arm 162. The second shaft 178 may also include a first sleeve 184 disposed about the core shaft 182. The first sleeve 184 may be disposed between the second arm 160 and the output belt 126. The second shaft 178 may further include a second sleeve 186 disposed about the core shaft 182. The second sleeve 186 may be disposed betweenthe output belt 126 and the third arm 162. The first sleeve 184, the second sleeve 186, and the core shaft 182 may collectively define the groove 180.

[0065] The lift assembly 100 may further include a second output belt 188 wound about the output shaft 122. The second output belt 188 may be wound at least partially about the second shaft 178. The second shaft 178 may define a second groove 190, and the second output belt 188 may be disposed at least partially in the second groove 190 to align the second output belt 188 upon winding the second output belt 188 about the second shaft 178. It is to be appreciated that the second output belt 188 need not be wound completely about the second shaft 178 in order for the second groove 190 to align the second output belt 188. In other words, the second groove 190 may align the second output belt 188 when the second output belt 188 is only partially wound about the second shaft 178. More specifically, the second shaft 178 may further include a third sleeve 192 disposed about the core shaft X, and the second output belt 188 may be disposed between the second sleeve 186 and the third sleeve 192. The second sleeve 186, the third sleeve 192, and the core shaft 182 may collectively define a second groove 190, and the second output belt 188 may be at least partially disposed in the second groove 190.

[0066] The first arm 158 may have a first cam surface 194, the second arm 160 may have a second cam surface 196, the third arm 162 may have a third cam surface 198, and the fourth arm 164 may have a fourth cam surface 200. The output belt 126 may have first and second ends 202, 204, with the first end 202 wound about the drive mechanism 108 to facilitate the movement of the platform 104 relative to the base 102. The lift assembly 100 may further include a third shaft 206 coupled to the scissor mechanism 106, and the second end 204 of the output belt 126 may be mounted to the third shaft 206. It is to be appreciated that the second end 204 of the output belt 126 need not be mounted directly to the third shaft 206 but instead may be mounted through one or more intervening components. The third shaft 206 may havea first bearing 208 contactable with the first cam surface 194, a second bearing 210 contactable with the second cam surface 196, a third bearing 212 contactable with the third cam surface 198, and a fourth bearing 214 contactable with the fourth cam surface 200 to guide the platform 104 between the raised position and the lowered position.

[0067] Both the second arm 160 and the third arm 162 have inner surfaces 216, 218 facing each other. The lift assembly 100 may further include a guide roller 220 rotatably coupled to the third shaft 206. The guide roller 220 is engageable with the inner surface 216 of the second arm 160 to guide the platform 104 between the raised position and the lowered position. The guide roller 220 may slide, or roll, across the inner surface 216 of the second arm 160 as the platform 104 moves between the raised position and the lowered position. Moreover, the lift assembly 100 may further include a guide shaft 222 extending transversely from the third shaft 206, and the guide roller 220 may be rotatable about the guide shaft 222.

[0068] The lift assembly 100 may further include a second guide roller 224 rotatably coupled to the third shaft 206. The second guide roller 224 is engageable with the inner surface 218 of the third arm 162 to guide the platform 104 between the raised position and the lowered position. The second guide roller 224 may slide, or roll, across the inner surface 218 of the third arm 162 as the platform 104 moves between the raised position and the lowered position. Moreover, the lift assembly 100 may further include a second guide shaft 226 extending transversely from the third shaft 206, and the second guide roller 224 may be rotatable about the second guide shaft 226. It is to be appreciated that the first guide roller 220 and the second guide roller 224 are spaced from one another along the third shaft 206, and that the first guide shaft 222 and the second guide shaft 226 are likewise spaced from one another along the third shaft 206.

[0069] The lift assembly 100 may also include a skirt 228 extending between the platform 104 and the base 102, with the skirt 228 enclosing the scissor mechanism 106 andthe drive mechanism 108. The skirt 228 prevents ingress of contaminants (e.g., dust) which may cause damage or wear to the components of the lift assembly 100, such as to the scissor mechanism 106 or the drive mechanism 108. Moreover, the skirt 228 may have a configuration whereby the skirt 228 is able to fold onto itself, such as an accordion configuration.

[0070] In a second aspect of the present invention, another embodiment of a lift assembly 100 is provided. The lift assembly 100 includes a base 102, a platform 104 moveable relative to the base 102 between a raised position and a lowered position, and a scissor mechanism 106 coupled to the base 102 and to the platform 104 to move the platform 104 relative to the base 102. The lift assembly 100 also includes a drive mechanism 108 coupled to the base 102. The drive mechanism 108 includes a mount block 110 extending along an axis Al and a plurality of electric motors 112 supported by the mount block 110. The electric motors 1 12 are arranged in series along the axis Al to define an initial electric motor 114, one or more intermediate electric motors 116, and a final electric motor 118. The drive mechanism 108 also includes a plurality of gears 120 each mounted to one of the electric motors 1 12 and a plurality of transmissions 136 each disposed between one of the series of electric motors 1 12 and one of the gears 120. Each of the transmissions 136 is configured to modulate torque provided to the gears 120 from the electric motors 112. The drive mechanism 108 further includes an output gear 124 spaced from the electric motors 112 and driven by the gear 120 mounted to the final electric motor 118. It is to be appreciated that the second aspect of the present invention described above may be used in combination with any other characteristics of any other lift assemblies as described herein.

[0071] In a third aspect of the present invention, another embodiment of a lift assembly 100 is provided. The lift assembly 100 includes a base 102, a platform 104 moveable relative to the base 102 between a raised position and a lowered position, and a scissor mechanism 106 coupled to the base 102 and to the platform 104 to move the platform 104relative to the base 102. The scissor mechanism 106 includes a first arm 158, a second arm 160, a third arm 162, and a fourth arm 164 each supported by the base 102 and extending toward the platform 104. The first arm 158 and the second arm 160 are pivotable relative to one another to define a first pair of scissor arms 166 to assist the platform 104 in moving between the raised position and the lowered position. The third arm 162 and the fourth arm 164 are pivotable relative to one another to define a second pair of scissor arms 168 to assist the platform 104 in moving between the raised position and the lowered position. Both the second arm 160 and the third arm 162 have inner surfaces 216, 218 facing each other.

[0072] The lift assembly 100 according to the third aspect of the invention also includes a drive mechanism 108 coupled to the base 102 and disposed between the first and second pairs of scissor arms 166, 168. The lift assembly 100 further includes an output belt 126 having first and second ends 202, 204, with the first end 202 wound about the drive mechanism 108 to facilitate the movement of the platform 104 relative to the base 102. The lift assembly 100 further includes a third shaft 206 coupled to the scissor mechanism 106, with the second end 204 of the output belt 126 mounted to the third shaft 206. The lift assembly 100 further includes a guide roller 220 rotatably coupled to the third shaft 206, with the guide roller 220 engaging the inner surface 216 of the second arm 160 to guide the platform 104 between the raised position and the lowered position. It is to be appreciated that the third aspect of the present invention described above may be used in combination with any other characteristics of any other lift assemblies as described herein.

[0073] For example, in the third aspect of the invention, the drive mechanism 108 may include a mount block 110 extending along an axis Al and a plurality of electric motors 112 supported by the mount block 110. The electric motors 112 may be arranged in series along the axis Al to define an initial electric motor 114, one or more intermediate electric motors 116, and a final electric motor 118. The drive mechanism 108 may also include aplurality of gears 120 each mounted to one of the electric motors 112, an output gear 124 driven by the gear 120 mounted to the final electric motor 118 to receive a combined rotational torque from the series of electric motors 112, and an output shaft 122 spaced from the series of electric motors 112 to receive the combined rotational torque from the output gear 124. The output belt 126 may be wound about the output shaft 122 upon rotation of the output gear 124.

[0074] Moreover, in the third aspect of the present invention, the output shaft 122 may have a lip 150 extending circumferentially about a distal end 152 of the output shaft 122 to retain the output belt 126 to the output shaft 122. Further still, in the third aspect of the present invention, the lift assembly 100 may further include a plurality of transmissions 136 each disposed between one of the series of electric motors 112 and the mount block 110. Each transmission 136 is configured to modulate torque provided to the gears 120 from the electric motors 112.

[0075] 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. Many modifications and variations of the present invention are possible in light of the above teachings, and the invention may be practiced otherwise than as specifically described.

Claims

CLAIMSWhat is claimed is:

1. A lift assembly comprising: a base; a platform moveable relative to said base between a raised position and a lowered position; a scissor mechanism coupled to said base and to said platform to move said platform relative to said base; a drive mechanism coupled to said base, said drive mechanism comprising, a mount block extending along an axis, a plurality of electric motors supported by said mount block, with said electric motors arranged in series along said axis to define an initial electric motor, one or more intermediate electric motors, and a final electric motor, a plurality of gears each mounted to one of said electric motors, an output shaft spaced from said electric motors and coupled to said mount block, an output gear rotationally coupled to said output shaft and driven by said gear mounted to said final electric motor to receive a combined rotational torque from said series of electric motors, and an output belt wound about said output shaft upon rotation of said output gear.

2. The lift assembly as set forth in claim 1, wherein said output shaft has a lip extending circumferentially about a distal end of said output shaft to retain said output belt to said output shaft.

3. The lift assembly as set forth in claim 1 further comprising a bearing supported by said base, and wherein said a distal end of said output shaft is supported by said bearing.

4. The lift assembly as set forth in claim 3, wherein said bearing is further defined as a pillow block.

5. The lift assembly as set forth in claim 1, wherein said output shaft forms a cantilever with a distal end of said output shaft free-floating.

6. The lift assembly as set forth in claim 1, wherein said scissor mechanism comprises a first arm, a second arm, a third arm, and a fourth arm each supported by said base and extending toward said platform; wherein said first arm and said second arm are pivotable relative to one another to define a first pair of scissor arms to assist said platform in moving between said raised position and said lowered position; wherein said third arm and said fourth arm are pivotable relative to one another to define a second pair of scissor arms to assist said platform in moving between said raised position and said lowered position; and wherein said drive mechanism is disposed between said first and second pairs of scissor arms.

7. The lift assembly as set forth in claim 6 further comprising a second shaft coupled to said second arm and said third arm, wherein said second shaft defines a groove, and wherein said output belt is disposed at least partially in said groove to align said output belt upon winding said output belt about said second shaft.

8. The lift assembly as set forth in claim 7, wherein said second shaft comprises a core shaft extending transverse to said second arm and said third arm, a first sleeve disposed about said core shaft and disposed between said second arm and said output belt, and a second sleeve disposed about said core shaft and disposed between said output belt and said third arm, and wherein said first sleeve, said second sleeve, and said core shaft collectively define said groove.

9. The lift assembly as set forth in claim 8 further comprising a second output belt wound about said output shaft, with said second output belt wound at least partially about said second shaft, wherein said second shaft further comprises a third sleeve disposed about said core shaft, wherein said second output belt is disposed between said second sleeve and said third sleeve, wherein said second sleeve, said third sleeve, and said core shaft collectively define a second groove, and wherein said second output belt is at least partially disposed in said second groove.

10. The lift assembly as set forth in claim 6, wherein said first arm has a first cam surface, wherein said second arm has a second cam surface, wherein said third arm has a third cam surface, wherein said fourth arm has a fourth cam surface, wherein said output belt has first and second ends with said first end wound about said drive mechanism to facilitate said movement of said platform relative to said base, and further comprising a third shaft coupled to said scissor mechanism, with said second end of said output belt mounted to said third shaft, and with said third shaft having a first bearing contactable with the first cam surface, a second bearing contactable with said second cam surface, a third bearing contactable with said third cam surface, and a fourth bearing contactable with said fourth cam surface to guide said platform between said raised position and said lowered position.

11. The lift assembly as set forth in claim 10, wherein both said second arm and said third arm have inner surfaces facing each other, and further comprising a guide roller rotatably coupled to said third shaft, with said guide roller engageable with said inner surface of said second arm to guide said platform between said raised position and said lowered position.

12. The lift assembly as set forth in claim 11 further comprising a guide shaft extending transversely from said third shaft, with said guide roller rotatable about said guide shaft.

13. The lift assembly as set forth in claim 11 further comprising a second guide roller rotatably coupled to said third shaft, with said second guide roller engageable with said inner surface of said third arm to guide said platform between said raised position and said lowered position.

14. The lift assembly as set forth in claim 1 further comprising a plurality of transmissions each disposed between one of the series of electric motors and said mount block, wherein said each transmission is configured to modulate torque provided to said gears from said electric motors.

15. The lift assembly as set forth in claim 14, wherein each of said plurality of transmissions is further defined as a planetary gearset.

16. The lift assembly as set forth in claim 14, wherein each of said plurality of transmissions is further defined as a plurality of planetary gearsets.

17. The lift assembly as set forth in claim 1 , wherein at least one of said gears mounted to at least one of said intermediate electric motors is an idler gear not directly driven by an electric motor.

18. The lift assembly as set forth in claim 1 further comprising a tensioner pulley supported by said base and contactable with said output belt when said platform is in said lowered position.

19. The lift assembly as set forth in claim 1, wherein said series of gears are in meshed relation with one another.

20. The lift assembly as set forth in claim 1 further comprising: a second mount block extending along a second axis; and a second plurality of electric motors supported by said second mount block, with said second plurality of electric motors arranged in series along said second axis to define a secondinitial electric motor, one or more second intermediate electric motors, and a second final electric motor; wherein said gear of said initial electric motor is also mounted to said second initial electric motor and said gear of said final electric motor is also mounted to said second final electric motor.

21. A lift assembly comprising: a base; a platform moveable relative to said base between a raised position and a lowered position; a scissor mechanism coupled to said base and to said platform to move said platform relative to said base; a drive mechanism coupled to said base, said drive mechanism comprising, a mount block extending along an axis, a plurality of electric motors supported by said mount block, with said electric motors arranged in series along said axis to define an initial electric motor, one or more intermediate electric motors, and a final electric motor, a plurality of gears each mounted to one of said electric motors, a plurality of transmissions each disposed between one of said series of electric motors and one of said gears, wherein each of said transmissions is configured to modulate torque provided to said gears from said electric motors; and an output gear spaced from said electric motors and driven by said gear mounted to said final electric motor.

22. A lift assembly comprising: a base;a platform moveable relative to said base between a raised position and a lowered position; a scissor mechanism coupled to said base and to said platform to move said platform relative to said base; wherein said scissor mechanism comprises a first arm, a second arm, a third arm, and a fourth arm each supported by said base and extending toward said platform; wherein said first arm and said second arm are pivotable relative to one another to define a first pair of scissor arms to assist said platform in moving between said raised position and said lowered position; wherein said third arm and said fourth arm are pivotable relative to one another to define a second pair of scissor arms to assist said platform in moving between said raised position and said lowered position; and wherein both said second arm and said third arm have inner surfaces facing each other; and a drive mechanism coupled to said base and disposed between said first and second pairs of scissor arms; an output belt having first and second ends with said first end wound about said drive mechanism to facilitate said movement of said platform relative to said base; a third shaft coupled to said scissor mechanism with said second end of said output belt mounted to said third shaft; and a guide roller rotatably coupled to said third shaft with said guide roller engaging said inner surface of said second arm to guide said platform between said raised position and said lowered position.

23. The lift assembly as set forth in claim 22, wherein said drive mechanism comprising,a mount block extending along an axis, a plurality of electric motors supported by said mount block, with said electric motors arranged in series along said axis to define an initial electric motor, one or more intermediate electric motors, and a final electric motor, a plurality of gears each mounted to one of said electric motors, an output gear driven by said gear mounted to said final electric motor to receive a combined rotational torque from said series of electric motors, and an output shaft spaced from said series of electric motors to receive the combined rotational torque from said output gear; and wherein said output belt is wound about said output shaft upon rotation of said output gear.

24. The lift assembly as set forth in claim 22, wherein said output shaft has a lip extending circumferentially about a distal end of said output shaft to retain said output belt to said output shaft.

25. The lift assembly as set forth in claim 22 further comprising a plurality of transmissions each disposed between one of the series of electric motors and said mount block, wherein said each transmission is configured to modulate torque provided to said gears from said electric motors.

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