Dual actuator assembly

A boom assembly includes a lower boom, an upper boom, and an actuator assembly. The lower boom has an upper end and a base end. The base end is configured to be pivotally coupled to a lift device. The upper boom has a lower end pivotally coupled to the upper end of the lower boom. The actuator assembly has (i) a first end coupled to at least one of the upper end of the lower boom and the lower end of the upper boom, and (ii) an opposing second end coupled to the upper boom. The actuator assembly includes a first actuator and a second actuator. The second actuator is rigidly joined to the first actuator at the first end of the actuator assembly and flexibly joined to the first actuator at the opposing second end of the actuator assembly.

BACKGROUND

Traditional articulated boom lifts may include a chassis, a turntable coupled to the chassis, and a boom assembly. An end of a first boom section is coupled to the turntable, and an opposing end of the first boom section may be coupled to a second boom section. A lift cylinder elevates the first boom section relative to the turntable and/or the second boom section relative to the first boom section, thereby elevating an implement (e.g., work platform, forks, etc.) that is coupled to the boom assembly.

SUMMARY

One embodiment relates to a boom assembly. The boom assembly includes a lower boom, an upper boom, and an actuator assembly. The lower boom has an upper end and a base end. The base end is configured to be pivotally coupled to a lift device. The upper boom has a lower end pivotally coupled to the upper end of the lower boom. The actuator assembly has (i) a first end coupled to at least one of the upper end of the lower boom and the lower end of the upper boom, and (ii) an opposing second end coupled to the upper boom. The actuator assembly includes a first actuator and a second actuator. The second actuator is rigidly joined to the first actuator at the first end of the actuator assembly and flexibly joined to the first actuator at the opposing second end of the actuator assembly.

Another embodiment relates to an actuator for a boom assembly. The actuator includes a first actuator, a second actuator arranged in parallel with the first actuator, a first coupler, a second coupler, a third coupler, and a fourth coupler. The first coupler is positioned to rigidly couple a first end of each of the first actuator and the second actuator together. The first coupler is configured to couple the first end of each of the first actuator and the second actuator to at least one of a lower boom and an upper boom of the boom assembly. The second coupler is positioned at an opposing second end of the first actuator. The second coupler is configured to couple the opposing second end of the first actuator to the upper boom of the boom assembly. The third coupler is positioned at an opposing second end of the second actuator. The third coupler is configured to couple the opposing second end of the second actuator to the upper boom of the boom assembly independent of the first actuator. The fourth coupler is positioned between (i) the first coupler and (ii) the second coupler and the third coupler. The fourth coupler flexibly couples the first actuator to the second actuator.

Still another embodiment relates to a lift device. The lift device includes a base, a boom assembly, and an actuator assembly. The boom assembly includes a first boom portion pivotally coupled to the base and a second boom portion pivotally coupled to the first boom portion. The actuator assembly has (i) a first end coupled to the first boom portion and (ii) an opposing second end coupled to the second boom portion. The actuator assembly includes a first actuator and a second actuator arranged in parallel with the first actuator. The second actuator is rigidly joined to the first actuator at the first end of the actuator assembly and flexibly joined to the first actuator at the opposing second end of the actuator assembly.

The invention is capable of other embodiments and of being carried out in various ways. Alternative exemplary embodiments relate to other features and combinations of features as may be generally recited in the claims.

DETAILED DESCRIPTION

According to an exemplary embodiment, a lift device includes an actuator assembly having two or more actuators (e.g., hydraulic cylinders, etc.) that are coupled (e.g., thereby forming a conjoined twin actuator arrangement, a parallel actuator assembly, etc.). In one embodiment, the two or more actuators are identical. The actuator assembly may be configured to selectively reposition (e.g., lift, rotate, elevate, etc.) at least a portion of a boom assembly including a first boom (e.g., a lower boom, a tower boom, etc.) and a second boom (e.g., a main boom, an upper boom, etc.). According to an exemplary embodiment, first ends (e.g., lower ends, etc.) of the two or more actuators are rigidly joined (e.g., with a single, rigid clevis bracket, etc.). In one embodiment, the first end of the actuator assembly is coupled to the first boom and the second boom with an intermediate link. In other embodiments, the first end of the actuator assembly is coupled to the first boom with an intermediate link. In still other embodiments, the first end of the actuator assembly is directly coupled to the first boom. According to an exemplary embodiment, a second end (e.g., an upper end, etc.) of the actuator assembly is directly coupled to the second boom. Second ends of the two or more actuators are flexibly coupled (e.g., with a flexible joint member, etc.), according to an exemplary embodiment. In one embodiment, the flexibly-joined end of each actuator of the actuator assembly includes a coupler (e.g., a clevis bracket, etc.) configured to interface the respective actuator with the second boom. Such an actuator assembly having conjoined twin actuators may facilitate the use of smaller diameter and less expensive actuators (e.g., hydraulic cylinders, etc.) in place of a single, larger diameter and more expensive actuator, thereby reducing the cost of the actuator assembly and lift device. The lift device may have a reduced overall height when configured in a stowed and/or non-extended orientation. By way of example, a lift device having the actuator assembly may have a more compact stowed and/or non-extended height relative to lift devices having a similarly-positioned single, larger diameter actuator design. By way of another example, a lift device having the actuator assembly may meet or exceed stowed height requirements for shipping and/or transport.

According to the exemplary embodiment shown inFIGS. 1-4, a lift device (e.g., an aerial work platform, a telehandler, a boom lift, a boom truck, etc.), shown as lift device10, includes a boom assembly, shown as boom40, coupled to a base, shown as lift base20. As shown inFIG. 1, the lift base20includes a chassis, shown as chassis22, and a supporting base structure, shown as turntable30, that is supported by the chassis22. According to an exemplary embodiment, the turntable30is rotatable relative to the chassis22. As shown inFIG. 1, the turntable30includes a counterweight, shown as tail counterweight32, coupled to a rear of the turntable30. In other embodiments, the tail counterweight32is otherwise positioned and/or at least a portion of the weight thereof is otherwise distributed throughout the lift device10(e.g., on the chassis22, on a portion of the boom40, etc.). As shown inFIG. 1, the chassis22is supported by a plurality of tractive elements, shown as tractive elements24. According to the exemplary embodiment shown inFIG. 1, the tractive elements24include wheels. In other embodiments, the tractive elements24include a track element. According to an exemplary embodiment, the tractive elements24are driven by a drive system, shown as drive system26. The drive system26may be controlled from a cab, a control panel at the turntable30, a control panel at a platform assembly, or from still another location.

As shown inFIGS. 1 and 2, the boom40includes a first, lower boom, shown as tower boom50, and a second, upper boom, shown as main boom70. According to an exemplary embodiment, the boom40is an articulating boom assembly. In one embodiment, the main boom70has a length that is greater than tower boom50. According to another exemplary embodiment, the boom40is a telescopic, articulating boom assembly. By way of example, the main boom70and/or the tower boom50may include a plurality of telescoping boom sections that are capable of extending and retracting along a longitudinal centerline to selectively increase and decrease a length thereof.

As shown inFIGS. 1 and 2, the tower boom50has a first end (e.g., lower end, etc.), shown as base end52, and an opposing second end, shown as upper end54. As shown inFIG. 1, the base end52of the tower boom50is pivotally coupled (e.g., pinned, etc.) to the turntable30at a joint, shown as tower boom pivot60. As shown inFIG. 1, the boom40includes a first actuator (e.g., pneumatic cylinder, electric actuator, hydraulic cylinder, etc.), shown as tower lift cylinder34. The tower lift cylinder34has a first end coupled to the turntable30and an opposing second end coupled to the tower boom50. According to an exemplary embodiment, the tower lift cylinder34is positioned to raise and lower the tower boom50relative to the turntable30about the tower boom pivot60.

As shown inFIGS. 1 and 2, the main boom70has a first end, shown as lower end72, and an opposing second end, shown as upper end74. As shown inFIGS. 1 and 2, the lower end72of the main boom70is pivotally coupled (e.g., pinned, etc.) to the upper end54of the tower boom50at a joint, shown as main boom pivot58. As shown inFIG. 1, the boom40includes an implement, shown as platform assembly92, coupled to the upper end74of the main boom70with an extension arm, shown as jib arm90. In some embodiments, the jib arm90is configured to facilitate pivoting the platform assembly92about a lateral axis (e.g., up and down, etc.). In some embodiments, the jib arm90is configured to facilitate pivoting the platform assembly92about a vertical axis (e.g., left and right, etc.). In some embodiments, the jib arm90is configured to facilitate extending and retracting the platform assembly92relative to the upper end74of the main boom70. According to an exemplary embodiment, the platform assembly92is a structure that is capable of supporting one or more workers. In some embodiments, an accessory or tool is coupled to the platform assembly92for use by a worker. Such tools may include pneumatic tools (e.g., impact wrench, airbrush, nail gun, ratchet, etc.), plasma cutters, welders, spotlights, etc. In some embodiments, the platform assembly92includes a control panel to control operation of the lift device10(e.g., the turntable30, the boom40, etc.) from the platform assembly92. In other embodiments, the platform assembly92is replaced with and/or includes an accessory or tool (e.g., forklift forks, etc.).

As shown inFIGS. 1 and 2, the boom40includes a second actuator (e.g., a conjoined twin actuator assembly, main boom actuator assembly, etc.), shown as actuator assembly100. According to an exemplary embodiment, the actuator assembly100is positioned to selectively reposition (e.g., lift, rotate, elevate, etc.) the main boom70relative to the tower boom50about the main boom pivot58. In some embodiments, the actuator assembly100is configured to replace the tower lift cylinder34. As shown inFIGS. 1-4, the actuator assembly100has a first end, shown as lower end102, and an opposing second end, shown as upper end104. As shown inFIGS. 2-4, the actuator assembly100includes a first actuator (e.g., pneumatic cylinder, electric actuator, hydraulic cylinder, etc.), shown as right actuator120, and a second actuator (e.g., pneumatic cylinder, electric actuator, hydraulic cylinder, etc.), shown as left actuator140.

As shown inFIGS. 2-4, the right actuator120includes a cylinder, shown as right cylinder122, having a first end, shown as lower end124, and an opposing second end, shown as upper end126. As shown inFIGS. 2-4, the right actuator120includes a cylinder head, shown as right cylinder head128, positioned at the upper end126of the right cylinder122. As shown inFIGS. 3 and 4, the left actuator140includes a cylinder, shown as left cylinder142, having a first end, shown as lower end144, and an opposing second end, shown as upper end146. As shown inFIGS. 3 and 4, the left actuator140includes a cylinder head, shown as left cylinder head148, positioned at the upper end146of the left cylinder142.

As shown inFIG. 4, the left actuator140includes a rod, shown as left cylinder rod150, disposed within an internal volume defined by the left cylinder142. The left cylinder rod150has a piston assembly (e.g., a piston, seals, etc.), shown as left piston152, positioned at an end thereof (e.g., a first end, a lower end thereof, an end proximate the lower end144of the left actuator140, etc.). As shown inFIG. 4, the left piston152separates the internal volume of the left cylinder142into a first chamber, shown as left retraction chamber154, and a second chamber, shown as left extension chamber156. According to an exemplary embodiment, the left extension chamber156increases in volume and the left retraction chamber154decreases in volume as the left cylinder rod150extends from the left cylinder142, and the left extension chamber156decreases in volume and the left retraction chamber154increases in volume as the left cylinder rod150retracts within the left cylinder142. As shown inFIG. 4, the left retraction chamber154forms a first, dynamic internal volume of the left cylinder142positioned between the left piston152and the left cylinder head148positioned at the upper end146of the left actuator140and the left extension chamber156forms a second, dynamic internal volume of the left cylinder142positioned between the left piston152and the lower end144of the left actuator140(e.g., the amount of volume within the first, dynamic internal volume and the second, internal volume is dependent on the position of the left piston152along the length of the left cylinder142, etc.).

According to an exemplary embodiment, the right actuator120includes a right cylinder rod (e.g., similar to the left cylinder rod150, etc.) disposed within an internal volume defined by the left cylinder142and has a right piston (e.g., similar to the left piston152, etc.) positioned at an end thereof (e.g., a first end, a lower end thereof, an end proximate the lower end124of the right actuator120, etc.). The right piston may separate the internal volume of the right cylinder122into a right retraction chamber (e.g., similar to the left retraction chamber154, etc.) and a right extension chamber (e.g., similar to the left extension chamber156, etc.). According to an exemplary embodiment, the right extension chamber increases in volume and the right retraction chamber decreases in volume as the right cylinder rod extends from the right cylinder122, and the right extension chamber decreases in volume and the right retraction chamber increases in volume as the right cylinder rod retracts within the right cylinder122. The right retraction chamber may form a first, dynamic internal volume of the right cylinder122positioned between the right piston and the right cylinder head128positioned at the upper end126of the right actuator120and the right extension chamber may form a second, dynamic internal volume of the right cylinder122positioned between the right piston and the lower end124of the right actuator120(e.g., the amount of volume within the first, dynamic internal volume and the second, internal volume is dependent on the position of the right piston along the length of the right cylinder122, etc.).

As shown inFIGS. 2-4, the actuator assembly100includes a first coupler (e.g., a rigid coupler, a single clevis joint, etc.), shown as lower coupling bracket160. According to an exemplary embodiment, the lower coupling bracket160is configured to pivotally couple the lower end102of the actuator assembly100to the boom40. According to the exemplary embodiment shown inFIGS. 2-4, the lower coupling bracket160includes a clevis bracket. In other embodiments, the lower coupling bracket160includes another type of bracket and/or coupler. As shown inFIGS. 3 and 4, the lower coupling bracket160includes a body, shown as coupling plate162. As shown inFIG. 3, the coupling plate162defines a pair of apertures, shown as cylinder apertures164. The cylinder apertures164are configured (e.g., sized, positioned, etc.) to receive the lower end124of the right cylinder122and the lower end144of the left cylinder142, thereby rigidly coupling the right actuator120and the left actuator140at the lower end102of the actuator assembly100. As shown inFIGS. 3 and 4, the lower coupling bracket160includes a plurality of extensions, shown as bracket arms166, extending from the coupling plate162. As shown inFIGS. 2 and 3, each of the bracket arms166define an aperture, shown as coupling aperture168.

As shown isFIGS. 1 and 2, the boom40includes a link, shown as intermediate link80. As shown inFIG. 2, the intermediate link80includes a first link, shown as link82, having a first end pivotally coupled (e.g., pinned, etc.) to the upper end54of the tower boom50at a joint, shown as pivot56, and a second end pivotally coupled (e.g., pinned, etc.) to the lower coupling bracket160at a joint, shown as pivot86. According to an exemplary embodiment, the second end of the link82defines an aperture configured (e.g., sized, positioned, etc.) to correspond with the coupling apertures168of the bracket arms166to receive a fastener (e.g., a clevis pin, etc.) and pivotally couple the link82to the lower coupling bracket160. The link82may thereby pivotally couple the lower end102of the actuator assembly100to the tower boom50.

As shown inFIG. 2, the intermediate link80includes a second link, shown as link84, having a first end pivotally coupled (e.g., pinned, etc.) to the lower end72of the main boom70at a joint, shown as pivot76, and a second end pivotally coupled (e.g., pinned, etc.) to the link82at a joint, shown as pivot88. The link84may thereby pivotally couple the lower end102of the actuator assembly100to the main boom70. In other embodiments, the intermediate link80does not include the link84such that the intermediate link80only couples the lower end102of the actuator assembly100to the tower boom50. In still other embodiments, the boom40does not include the intermediate link80. In such an embodiment, the lower coupling bracket160may be configured to directly couple the actuator assembly100to the tower boom50at the pivot56.

As shown inFIGS. 2-4, the actuator assembly100includes a second coupler, shown as upper, right coupling bracket170, coupled to the upper end126of the right cylinder122(e.g., to an opposing second end of the right cylinder rod opposite the right piston, etc.). As shown inFIGS. 3 and 4, the actuator assembly100includes a third coupler, shown as upper, left coupling bracket174, coupled to the upper end146of the left cylinder142(e.g., to an opposing second end of the left cylinder rod150opposite the left piston152, etc.). According to the exemplary embodiment shown inFIGS. 2-4, the upper, right coupling bracket170and the upper, left coupling bracket174each include a clevis bracket. In other embodiments, the upper, right coupling bracket170and/or the upper, left coupling bracket174include another type of bracket and/or coupler. As shown inFIGS. 2-3, the upper, right coupling bracket170and the upper, left coupling bracket174each define apertures, shown as coupling aperture172and coupling aperture176, respectively.

As shown inFIG. 2, the main boom70includes an interface, shown as cylinder interface96, positioned along a length of the main boom70(e.g., between the lower end72and the upper end74of the main boom70, etc.). According to an exemplary embodiment, the cylinder interface96defines an aperture. The aperture of the cylinder interface96may be configured (e.g., sized, positioned, etc.) to align with the coupling apertures172of the upper, right coupling bracket170and the coupling apertures176of the upper, left coupling bracket174to receive a fastener (e.g., a single clevis pin, etc.). The upper, right coupling bracket170and the upper, left coupling bracket174may thereby directly and cooperatively pivotally couple the upper end104of the actuator assembly100to the main boom70at a joint, shown as pivot78(e.g., each of the right actuator120and the left actuator140is independently coupled to the main boom70; the upper, right coupling bracket170couples the right cylinder122to the main boom70; the upper, left coupling bracket174couples the left cylinder142to the main boom70; etc.). In other embodiments, (i) the lower coupling bracket160is coupled to the lift base20and (ii) the right coupling bracket170and the left coupling bracket174are coupled to the tower boom50(e.g., the actuator assembly100replaces the tower lift cylinder34, the boom40only includes the tower boom50, etc.).

As shown inFIGS. 3 and 4, the actuator assembly100includes a fourth coupler (e.g., a flexible joint member, a flexible element, a flexible coupler, etc.), shown as upper coupler178, positioned to flexibly join the upper end126of the right cylinder122and the upper end146of the left cylinder142. According to an exemplary embodiment, the actuator assembly100having a flexible joint provided by the upper coupler178facilitates the upper end126of the right cylinder122and the upper end146of the left cylinder142to move, flex, and/or float relative to one another as the boom40(e.g., the main boom70, the cylinder interface96, the tower boom50, the intermediate link80, etc.) moves in response to various loading conditions (e.g., torsional loading, non-longitudinal loading imparted by deflection of the lift device10, etc.). By way of example, the upper coupler178may provide a target amount of flex and/or movement such that the actuator assembly100is not subject to high, non-longitudinal stresses induced from movement and/or deflection of surrounding structures (e.g., the cylinder interface96, the main boom70, the tower boom50, the intermediate link80, etc.).

As shown inFIGS. 2-4, the actuator assembly100includes a valve assembly having a valve block, shown as actuator valve block180. As shown inFIGS. 3 and 4, the actuator valve block180includes a first flow conduit, shown as right retraction chamber tube182; a second flow conduit, shown as right extension chamber tube184; a third flow conduit, shown as left retraction chamber tube186; and a fourth flow conduit, shown as left extension chamber tube188. According to an exemplary embodiment, the right retraction chamber tube182fluidly couples the actuator valve block180with the right retraction chamber of the right cylinder122, the right extension chamber tube184fluidly couples the actuator valve block180with the right extension chamber of the right cylinder122, the left retraction chamber tube186fluidly couples the actuator valve block180with the left retraction chamber154of the left cylinder142, and the left extension chamber tube188fluidly couples the actuator valve block180with the left extension chamber156of the left cylinder142. The actuator valve block180may thereby be in fluid communication (e.g., hydraulic fluid communication, etc.) with each of the right extension chamber of the right cylinder122, the right retraction chamber of the right cylinder122, the left retraction chamber154of the left cylinder142, and the left extension chamber156of the left cylinder142.

According to an exemplary embodiment, the actuator valve block180includes an individual valve block having single set of load holding valves. The single set of load holding valves may include (i) a first holding valve (e.g., a retraction chamber holding valve, etc.) fluidly coupled to the right retraction chamber tube182and the left retraction chamber tube186and (ii) a second holding valve (e.g., an extension chamber holding valve, etc.) fluidly coupled to the right extension chamber tube184and the left extension chamber tube188. The actuator assembly100having the actuator valve block180provides several advantages relative to systems employing multiple valve blocks and/or multiple sets of loading holding valves (e.g., a first independent valve block associated with the right actuator120and a second independent valve block associated with the left actuator140, etc.).

By way of example, the actuator valve block180may facilitate providing equal pressures within the right cylinder122and the left cylinder142during an extension operation and/or a retraction operation thereof. The actuator assembly100may thereby facilitate providing equal forces with the right actuator120and the left actuator140to the main boom70. A dual valve block design may operate non-uniformly (e.g., where the two cylinders operate in a ratcheting fashion as the extension operations and the retraction operations of each cylinder may not be synchronized, etc.). According to an exemplary embodiment, the actuator valve block180eliminates such ratcheting, as the right actuator120and the left actuator140are driven by a single source, the actuator valve block180.

By way of another example, the actuator valve block180may facilitate providing even loading even upon failure of a seal within the actuator assembly100(e.g., in the right actuator120, in the left actuator140, etc.). Systems having two sets of load holding valves may exhibit uneven loading as the failed cylinder may not maintain pressure and provide a lower force, while the operational cylinder may remain at a target pressure. According to an exemplary embodiment, the actuator valve block180eliminates such uneven loading even during a seal failure in one of the cylinders by distributing the load through a single set of load holding valves (e.g., one load holding valve for the pair of extension chambers and one load holding valve for the pair of retraction chambers).

As shown inFIG. 2, the actuator assembly100is positioned between the main boom70and the tower boom50, within a region, shown as actuator space98, when the boom40is configured in a stowed position. According to an exemplary embodiment, the conjoined twin cylinder arrangement of the actuator assembly100facilitates decreasing a dimension of the actuator space98relative to traditional, single cylinder actuator designs, making the boom40more compact (e.g., a collapsed or stowed height thereof, allowing the lift device10to meet stowed height requirements for transportation, etc.). According to an exemplary embodiment, the conjoined twin cylinder arrangement of the actuator assembly100facilitates the use of smaller diameter cylinders (e.g., eight inch diameter cylinders, etc.) in place of a single, large diameter cylinder (e.g., a twelve inch diameter cylinder, etc.), while still generating the same or increased force. The larger diameter cylinder required for a single cylinder design may not fit within the reduced region of the actuator space98and/or may require special materials (e.g., expensive materials, materials that are difficult to obtain, non-existent materials, etc.) to construct.