Electric lifter

Abstract

The invention provides an electric lifter, comprising a fixed mast structure, a movable mast structure that is movable relative to the fixed mast structure at feast one transmission means (chain or cog drive belt or rack or similar), and a load carrier, in particular a fork load carrier, being connected to the at least one transmission means and configured to carry a load, wherein the at least one transmission means is movably connected to the movable mast structure while being configured to move along a closed loop path, the closed loop path being stationary relative to the movable mast structure.

Claims

1. A lifter comprising: a fixed mast structure; a movable mast structure that is movable relative to the fixed mast structure; at least one transmission assembly, the transmission assembly comprising a motor and at least one drive member; and a load carrier, connected to the at least one drive member and structured to carry a load, wherein the at least one drive member is movably connected to the movable mast structure and is structured to move along a respective closed loop path, wherein the at least one drive member is structured to transmit a lifting force from the motor to the load carrier, and wherein the lifter is structured to lift the load carrier in a first stage by moving the at least one drive member along the closed loop path while lifting the load carrier connected to the at least one drive member, and wherein the lifter is structured to lift the load carrier in a second stage by the at least one drive member transmitting a lifting force through the load carrier to the movable mast structure to thereby cause the load carrier to lift the moveable mast structure.

2. The lifter according to claim 1, wherein the movable mast structure is stationary during the first stage, and wherein the at least one drive member is stationary along the closed loop path during the second stage.

3. The lifter according to claim 2, wherein the movable mast structure comprises a stop retainer that is structured to stop the relative motion between the load carrier and the movable mast structure at the end of the first stage.

4. The lifter according to claim 1, further comprising at least one driving pinion for driving the at least one drive member, the driving pinion being attached to the fixed mast structure.

5. The lifter according to claim 4, further comprising one or more retaining rolls structured to provide an engaging connection between the at least one driving pinion and the at least one drive member.

6. Lifter according to claim 1, further comprising at least one rack, in particular a toothed rack, rigidly connected to the movable mast structure and at least one rack pinion engaging the at least one rack and for driving the at least one rack.

7. The lifter according to claim 1, further comprising at least one guiding pinion, wherein the at least one guiding pinion is attached to the movable mast structure and is structured to guide the at least one drive member.

8. The lifter according to claim 1, further comprising an additional movable mast structure and an additional drive member for providing a connection between the additional movable mast structure and the fixed mast structure and structured to implement a third lifting stage.

9. The lifter according to claim 1, wherein the motor is an electric motor configured to provide power to the at least one drive member for lifting the load carrier during a lifting phase.

10. The lifter according to claim 9, wherein the electric motor is configured and managed to generate electric power during a lowering phase.

11. The lifter according to claim 10, wherein the electric motor is managed by a controller in order to charge an electric accumulator or wherein the electric motor is connected to an electro-brake.

12. The lifter according to claim 9, comprising an epicycloidal gearbox connected to the electric motor, wherein an external ring gear of the epicycloidal gearbox engages a rack rigidly connected to the fixed part of the lifter, and wherein at least one planetary gear of the epicycloidal gearbox is connected to a shaft with at least one driving pinion attached thereto, the at least one driving pinion engaging with wherein torque generated by the external ring gear and the at least one planetary gear are calculated to provide a lifting of the load carrier in a first stage and a lifting of the load carrier and the movable mast structure in a second stage.

13. A lift-truck comprising the lifter according to claim 1.

14. The lifter according to claim 1, wherein the load carrier is a fork load carrier.

15. The lifter according to claim 1, wherein the at least one drive member comprises at least one chain or rack.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIGS. 1 and 2 illustrate a first embodiment of the invention, “free lift” configuration in side and front view.

(2) FIG. 3 illustrates a second embodiment of the invention, side view.

(3) FIGS. 4 and 5 illustrate a third embodiment of the invention, two stages configuration (duplex), side and rear view.

(4) FIGS. 6 and 7 illustrate a fourth embodiment of the invention, two stages configuration (duplex) with free lift, side and front view.

(5) FIG. 8 illustrates a fifth embodiment of the invention, three stages configuration (triplex) with free lift, side view.

(6) FIGS. 9-12 illustrates a sixth embodiment of the invention.

(7) FIG. 13 illustrates a possible flexible connection between the transmission means and the forks carriage.

DETAILED DESCRIPTION OF THE INVENTION

(8) In the drawings the reference numbers denote the following: 100 driving pinion/driving chain pinion 105 guiding pinion/guiding chain pinion 110 transmission means (chain or positive drive belt or cog belt or rack) 120 forks carriage 130 forks 140 electric motor with gearbox 150 fixed mast structure 160 movable mast structure 165 rack pinion 170 rack 180 retaining roll 190 electro brake 200 stop retainer 210 transmission means hook/chain hook 215 epicycloidal reduction gearbox 220 pinion of the epicycloidal gearbox connected to the electric motor 230 planet gear of the epicycloidal gearbox directly connected to the driving pinion or through a shaft and an additional part 245 240 ring gear of the epicycloidal gearbox connected to the rack or to the rack pinion 245 driving pinion/chain pinion connected to the chain 250 plain washer 260 forks carriage connection 270 load

(9) The most simple embodiment of the invention is described in FIGS. 1 and 2, a typical “free lift” configuration, in which for example an electric motor M, with an electro brake EF and a gearbox R, by means of a shaft S and one or two driving pinions 100, drives one or more transmission means a drive member, (namely a chain or positive drive belt or cog belt or rack or similar) 110 which lift the load 270 positioned on the forks 130. In particular one of the pinions is implemented as “drive” 100 and the other one as a guiding pinion 105. The transmission means is moving in a loop path around the guiding pinions with the fork carriage being connected to each end of the transmission means 110.

(10) FIG. 3 shows the operating principle of a mast without “free lift” option, where the forks maximum height is approximately the double of the fixed mast structure (or column) height. With this solution, when the load L is lifted, the mobile column (the movable mast structure) 160 is lifted as well, thus increasing the height of the whole lifting system. The system works with an electric motor with a gearbox which, by means of a rack pinion, drives a rack that lifts the mobile column 160. The rack is rigidly connected to the mobile column 160.

(11) FIGS. 4 and 5 provide for a different implementation of the same concept, in a 2 stages configuration (duplex), respectively in side and rear view.

(12) FIGS. 6 and 7 show the solution of a lifting system with “free lift” as first act, 2 stages configuration, side and front view, in the first lifting stage, according to free lift movement, there are not relative movements between fixed and movable mast structures; the advantage is that the overall height of the lifting structure does not increase. When the forks carriage 120 hits the stop retainer 200 and stops, the transmission means 110 will lift both the forks carriage 120 and the mobile column 160, at the same speed. This is the second lifting stage, during which the load L is lifted up to a height which is almost double than the fixed column.

(13) FIG. 8 shows the solution of a lifting system with “free lift” as first act, 3 stages configuration, side view. The lifter comprises an additional movable mast structure 160 and an additional transmission means, if compared to two stages configuration.

(14) The clamping system of the forks carriage 120 and the transmission means 110 will be accurately studied to allow the transition through the driving pinion 100 and the retaining roll or rolls 180. FIG. 13 shows an example of a possible implementation, without limitations and restrictions.

(15) FIGS. 9, 10, 11 and 12 show another possible embodiment of the invention. The electric motor M and, if necessary, the gearbox R drives an epicycloidal gearbox (refer to FIG. 9) which is designed to generate different output torque in order to create a sequence of the movements; during the lifting phase, the forks carriage 120 moves first and then the mobile column 160 moves; following the same principle, during the lowering phase, the mobile column 160 will lower first, and then the forks carriage 120.

(16) In particular, the invention provides the following embodiments:

(17) 1.) Fully electric lifter system that, by means of an electric motor and a transmission means (ref. FIG. 6), lifts loads wherein, with the controlled movement of the transmission means 110, it carries out both the function of “free lift” (first step) and the function to lift completely the mobile column 160 with the correct lifting sequence (second step) in this two stages example; in case of a non “free lift” implementation, with only an half turn of the transmission means 110 (see FIGS. 4 and 5), it carries out the function to lift completely the forks 130, lifting at the same time completely the mobile column 160 up to the top by means of a rack fixed to the mobile column.
2.) Fully electric lifter system made by an electric motor connected to an epicycloidal gearbox (ref. FIG. 9), wherein an external ring gear 240 of the gearbox engages a rack rigidly connected to the fixed part of the lifting structure (ref. FIG. 12) and wherein at least one planetary gear of the gearbox is connected to a shaft with at least one driving pinion 245 attached thereto, the at least one driving pinion engaging with the transmission means 110, in particular, wherein the torques generated by the external ring gear and the at least one planetary gear are respectively calculated to provide a lifting of the load carrier 120 in a first stage, in free movement, and a lifting of the load carrier and the movable mast structure 160 together in a second stage.
3.) A Lifter as defined in embodiment 1 that has one or more retaining rolls, as shown in FIGS. 6 and 7, item 180, that ensure a strong and reliable connection between the driving pinion 100 and the lifting transmission means 110.
4.) A Lifter as defined in embodiments 1 and 3 in which a single turn of the transmission means 110 allows first the lifting of the forks carriage 120 implementing the concept of “free lift” and then the lifting, at the same time, of the forks carriage 120 and the mobile column 160.
5.) A Lifter as defined in embodiments 1, 2, 3 and 4 where the lowering of forks carriage, mobile mast structure and accessories allows the energy recovery of the potential energy accumulated during the lifting actions of forks carriage, mobile mast structure and accessories. In the case of lowering weights, loads and goods in general, also their own potential energy will be converted to electric energy.
6.) A Lifter as defined in embodiments 1, 2, 3 and 4 wherein it is implemented a mobile flexible connection between the transmission means and the forks carriage (FIG. 13) that allows the transition through the driving pinions 100 and the retaining rolls 180.
7.) A Lifter as defined in embodiments 1, 2, 3, 4, 5 and 6 that, by means of an additional transmission means, implements a lifting feature based on the concept of triplex column (FIG. 8).

(18) An important feature has to be underlined: during the lifting phase the electric motor provides energy to the mobile part of the lifting structure and to the load which is accumulated as potential energy Wp:
Wp=L×h+L1×h1,
where L is the load L1 is a part of the lifting structure h is the load lifting height h1 is the lifting height of a part of lifting structure.

(19) During the lowering phase this energy is given back to the electric motor that, in this operating condition, works like a generator and regenerates energy back to the mains or, for example, to the battery.

(20) According to the electric solution with an electric motor and a gearbox an estimate of the efficiency η of the following components can be given: Electric motor: 80%, Reduction gearbox: 95%. Therefore, the total efficiency is about η: 0.8×0.95=76%.

(21) The electric motor M is usually connected to an electronic power converter that regulates the power to the motor during the lifting phase (driving) and regulates the power of the generator back to the mains or to the battery during the lowering phase (regenerating).

(22) Having described the preferred embodiments, it will become apparent that various modifications can be made, without departing from the scope of the invention as defined in the accompanying claims.