NL2021629B1

NL2021629B1 - Lift unit

Info

Publication number: NL2021629B1
Application number: NL2021629A
Authority: NL
Inventors: Peerboom Leopold
Original assignee: Almotion B V
Priority date: 2018-09-14
Filing date: 2018-09-14
Publication date: 2020-05-06

Abstract

Lift unit (1) comprising: - a carriage (7) and an elongated base (3) for translating said carriage (7) in a longitudinal direction (A) with respect to said elongated base (3), - a pulley (19) which is rotatable about a first rotation axis (23), - a flexible element (13) that is passed over said pulley (19), wherein said flexible element (13) at a first end thereof is connected to said carriage (7), - a counterweight element (11), connected to said flexible element (13) at a second end of said flexible element (13) such that said counterweight element (11) is only connected to said carriage (7) via said flexible element (13), wherein said counterweight element (11) is arranged for providing a counterweight to said carriage (7), wherein said counterweight element (1 1) is arranged in a receiving space provided in said elongated base (3) such that said counterweight element (11) is displaced in said receiving space when translating said carriage (7) in said longitudinal direction (A), wherein a dimension of said counterweight element (11) in a direction perpendicular to said longitudinal direction (A) is in the range of 1 mm to 3 mm smaller than the corresponding inner dimension of said receiving space.

Description

Title: Lift unit

Description

The present disclosure relates to a lift unit.

Lift units for translating a carriage in a vertical direction are known. Such a unit comprises two pulleys wherein a flexible element is passed over the two pulleys. The carriage is attached to the flexible element such that by rotating the pulleys the carriage may be moved in the vertical direction.

The lift unit may also be referred to as a linear unit or a motion system and is typically used for positioning an object at a desired height. An example of such a use is in machines for moving a product holder from a lower position to a higher position wherein for the product can only be reliably handled when the product is positioned with sufficient accuracy. An important aspect of the lift unit is a relative to provide for a relative safe lift unit while maintaining the lift unit relative compact. Another relevant aspect of the lift unit is power consumption for lifting the object to a position and/or maintaining the object at a position.

An object of the present disclosure is to provide a lift unit that is relative safe and compact and has a relative low power consumption for lifting the object to a position and/or maintaining the object at a position.

This objective is realised by the lift unit according to the present disclosure. The lift unit according to the present disclosure comprises a carriage and an elongated base for translating said carriage in a longitudinal direction with respect to said elongated base. The carriage is attached to a counterweight element via a flexible element. The flexible element is at a first end thereof connect to said carriage and at a second end thereof connected to said counterweight. The lift unit comprises a pulley that is rotatable about a first rotation axis, wherein said flexible element is passed over said pulley.

The counterweight element is arranged for providing a counterweight to said carriage, wherein said counterweight element preferably is arranged in a receiving space provided in said elongated base such that said counterweight is displaced in said receiving space when translating said carriage in said longitudinal direction. By providing a counterweight a relative low force is required for lifting the object, in use, to a vertical position and/or maintaining the object, in use, at a vertical position. The counterweight furthermore contributes to realising a relative safe lift unit in that the force required for lifting the object may be reduced.

The present disclosure at least partly relies on the insight that by providing the counterweight inside the elongated base a relative compact and safe lift unit may be realised. By providing the counterweight element inside the elongated base, the counterweight may be shielded from the surrounding of the lift unit and thereby avoid, or at least significantly reducing, the risk of an operator or object to collide with the counterweight.

It is advantageous if said lift unit comprises a translation element, wherein said carriage is connected to said elongated base via said translation element. Providing a translation element is advantageous for realising a relative accurate movement of the carriage, thereby realising a functional decoupling for realising a required stiffness, by said elongated base, and an accurate positioning of the carriage.

Preferably, said lift unit comprises an end part that is connected to said elongated base, wherein said pulley is provided in said end part. Providing a separate end part is beneficial for allowing said elongated base to have a relative low complexity.

In a practical embodiment of the lift unit according to the present disclosure, said end part provides an end stop for limiting said translation in said longitudinal direction. This is beneficial for realising a relative safe lift unit, wherein translation of said carriage is limited to a predetermined height.

It is beneficial if said lift unit comprises a drive arrangement connected to said pulley for rotating said pulley about said first rotation axis and thereby translating said carriage in said longitudinal direction.

Preferably a perimeter of said elongated base, in a direction perpendicular to said longitudinal direction, is closed. This is beneficial for shielding the counterweight element the surrounding of the lift unit and thereby avoid, or at least significantly reducing, the risk of an operator or object to collide with the counterweight.

In an embodiment said counterweight element is glidingly received in said elongated base. This is beneficial for avoiding a change of orientation, such as rotation or tilting, of said counterweigh relative to said elongated base. It is noted that such a change of orientation may result in a change of the required power consumption while changing a position of the object. Moreover, a change in orientation may due to friction of the counterweight with the elongated base result in a reduced positioning accuracy.

It is advantageous if said flexible element comprises a toothed belt and wherein said pulley comprises teeth arranged for cooperating with teeth of said toothed belt. A combination of a toothed belt and a toothed pulley is beneficial for avoiding, or at least significantly reduce, the risk of the flexible element moving relative to the pulley and thereby reduce a positioning accuracy of the carriage.

Preferably, a weight of said counterweight element is larger than a weight of said carriage. This is beneficial for realising a lift unit wherein, in the absence of a driving force for driving the pulley, a drop of the carriage to a lower position is avoided, or at least, the a speed of lowering the carriage is reduced.

It is beneficial if said elongated base comprises an extruded profile.

In an embodiment said elongated base is arranged for attachment of the lift unit to a structure for holding the lift unit. This is beneficial for realising a lift unit having a relative low complexity while being relative compact

In an embodiment of the lift unit according to the present disclosure, said elongated base, at a side of said elongated base opposite a side of said elongated base attached to said translation element, is arranged for attachment of the lift unit to a structure for holding the lift unit. This is beneficial for avoiding deformation of the elongated base due to weight of the object that is to be positioned and translated in the vertical direction.

Preferably, the counterweight element is only connected to said carriage via said flexible element. This is beneficial for avoiding the need for a second pulley at a lower side of the elongated base and the need for the flexible element to be endless for passing the flexible element over the first and second pulley. In other words, the counterweight element is hangs freely inside said elongated base.

In an embodiment of the lift unit according to the present disclosure, said end part comprises a pulley receiving space that is bound by an internal wall of said end part, wherein said pulley receiving space is dimensioned such that, in use, said internal wall limits a movement of said flexible element for maintaining said cooperation between said teeth of said pulley (19) and said toothed belt. This is beneficial for avoiding the flexible toothed element to move relative to the toothed pulley.

Preferably, said lift unit comprises a blocking organ for blocking movement of said counterweight element outside said elongated base. This is beneficial for shielded the counterweight element from the surrounding of the lift unit and thereby avoid, or at least significantly reducing, the risk of an operator or object to collide with the counterweight.

Preferably, a dimension of said counterweight element in a direction perpendicular to said longitudinal direction is in the range of 1 mm to 3 mm smaller than a corresponding inner dimension of said receiving space. This is beneficial for avoiding a change of orientation, such as rotation or tilting, of said counterweigh relative to said elongated base. It is noted that such a change of orientation may result in a change of the required power consumption while changing a position of the object. Moreover, a change in orientation may due to friction of the counterweight with the elongated base result in a reduced positioning accuracy.

The present disclosure will now be explained by means of a description of a preferred embodiment a lift unit according to the present disclosure, in which reference is made to the following schematic figures, in which:

Fig. 1: an exploded view of parts of a lift unit according to the present disclosure are shown;

Fig. 2: a side view of a lift unit according to the present disclosure is shown;

Fig. 3: a cross-section of the lift unit from Fig. 2 is shown;

Fig. 4: another side view of the lift unit from Fig. 2 is shown;

Fig. 5: elements of the lift unit from Fig. 2 are shown; Fig. 6: a side view of the lift unit from Fig. 2 is shown.

Lift unit 1 comprises an elongated base 3 and a carriage 7. The elongated base 3 extends in a longitudinal direction A and comprises a single part of extruded profile. Extruded profiles are well known and commonly used for motion systems. Lengths of these profiles in a lift unit can vary depending on the desired length of the unit. Extruded profiles provide required stiffness to the lift unit 1 for allowing a relative accurate movement of the carriage 7. In particular any bending of the lift unit 1 due to for instance a load of an object that needs to be lifted is prevented, or at least significantly reduced by said extruded profile. This allows for a decoupling of a required stiffness of the lift unit 1 and an accurate positioning of the carriage 5 in the longitudinal direction A. The extruded profile 3 is a so-called closed profile having a perimeter, in a direction perpendicular to said longitudinal direction A, that is closed. In other words, the outer perimeter of the extruded profile is continuous, apart from through holes and openings that may be provided in the extruded profile after extrusion of the profile. Alternatively it is conceivable that the elongated base 3 is formed from a profile made from bending sheet material, such as a steel plate.

At a first side of the extruded profile 3 a translation element in the form of a rail guide 9 is attached to the extruded profile 3. The carriage 7 is designed such that the carriage 7 may be guided along the rail guide 9 in said longitudinal direction A. At a side of the carriage 7 opposite said rail guide 9, the carriage 7 is provided with an interface element 5 for attaching an end effector (not shown) or object (not shown) to the lift unit 1. At a second side of the extruded profile 3, opposite said first side of the extruded profile 3, the elongated base 3 is arranged for attachment of the lift unit 1 to a structure (not shown) for holding the lift unit 1 at a predetermined position.

The lift unit 1 is further provided with an end part 21 that is attached to the extruded profile 3 at an outer end thereof, that in use, wherein the extruded profile 3 is positioned substantially vertically, preferably vertical, forms an upper outer end of the extruded profile 3. The end part 21 is dimensioned such that the translation of the carriage 7 at an upper translation range is limited by the end part 21. In other words, the end part 21 provides an end stop for limiting a translation of the carriage 7 in the vertical direction to a predetermined height. The end part 21 houses a toothed pulley 19 that may be driven by a drive arrangement formed by an electromotor (not shown) for rotation of the pulley 19 about a rotation axis 23.

A counterweight element 11 is provided inside the extruded profile 3. The dimensions of a cross-section of the counterweight element 11 perpendicular to said longitudinal direction A are smaller than the inner dimensions of a cross-section of the extruded profile 3 perpendicular to said longitudinal direction A for allowing said counterweight element 11 to move inside said extruded profile 3. Preferably, said dimensions of said counterweight element are in the range of 1 - 3 mm smaller than said inner dimensions of said extruded profile 3. At a, in use, lower side the elongated base 3 is provided with a blocking organ in the form of a screw 25 for blocking the counterweight element 11 to exit the extruded profile 3.

The counterweight element 3 is connected to said carriage 7 via a toothed belt 13. The counterweight element 3 is attached to the toothed belt through a first connection arrangement 15 and the carriage 7 is attached to the toothed belt trough a second connection arrangement 17. The toothed belt 13 is passed over said pulley 19 such that said counterweight element 11 provides a counterweight to said carriage 7. The teeth (not shown) of the toothed belt 13 are arranged to cooperate with teeth of said pulley 19 to avoid, or at least significantly reduce, the risk of the flexible element 13 moving relative to the pulley 19. The weight of the counterweight element 11 is larger than the combined weight of said carriage 7 and said interface element 5 such that in a situation wherein said pulley 19 is not powered by said drive arrangement the interface element 5 collides with said end part 21.

Claims

CONCLUSIONS

Lift unit (1) comprising:

a carriage (7) and an elongated base (3) for translating the carriage (7) in a longitudinal direction (A) relative to the elongated base (3), a pulley (19) arranged about a first axis of rotation (23) rotatable, a flexible element (13) wrapped around the pulley (19), the flexible element (13) being connected to the carriage (7) at a first end thereof, a counterweight element (11) a second end of the flexible element (13) is connected so that the counterweight element (11) is connected to the carriage (7) only through the flexible element (13), the counterweight element (11) being arranged to be a counterweight for the carriage ( 7), wherein the counterweight element (11) is provided in a receiving space in the elongated base (3) such that the counterweight element (11) moves in the receiving space when the carriage (7) moves in the longitudinal direction (A), wherein a dimension of the counterweight element (11) in a ric perpendicular to the longitudinal direction (A) in the range of 1 mm to 3 mm is smaller than a corresponding inner dimension of the receiving space.

Elevator unit (1) according to claim 1, wherein the elevator unit (1) comprises a translation element (9), the carriage (7) being connected to the elongated base (3) via the translation element (9).

Lift unit (1) according to claim 1 or 2, wherein the lift unit (1) comprises an end part (21) connected to the elongated base (3), the pulley (19) being provided in the end part (21).

Elevator unit (1) according to claim 3, wherein the end part (21) forms an end stop for limiting translation in the longitudinal direction (A).

Elevator unit (1) according to any of the preceding claims, wherein the elevator unit (1) comprises a drive arrangement connected to the pulley (19) for rotating the pulley (19) about the first axis of rotation (23) thereby translating the carriage (7) in the longitudinal direction (A).

Elevator unit (1) according to any of the preceding claims, wherein a circumference of the elongated base (3) is closed in a direction perpendicular to the longitudinal direction (A).

Elevator unit (1) according to any of the preceding claims, wherein the counterweight element (11) is kept sliding in the elongated base (3).

Elevator unit (1) according to any of the preceding claims, wherein the flexible element (13) comprises a toothed belt and the pulley (19) comprises teeth adapted to cooperate with the teeth of the toothed belt.

Elevator unit (1) according to any of the preceding claims, wherein a weight of the counterweight element (11) is greater than a weight of the carriage (7).

Elevator unit (1) according to any of the preceding claims, wherein the elongated base comprises an extruded profile.

Elevator unit (1) according to any of the preceding claims, wherein the elongated base (3) is arranged for attaching the elevator unit (1) to a structure for holding the elevator unit (1).

Elevator unit (1) according to claims 2 and 11, wherein the elongated base (3) is on one side of the elongated base (3) opposite to the side of the elongated base (3) attached to the translation element (9 ) is adapted for mounting the lift unit (1) with a structure for holding the lift unit (1).

Elevator unit (1) according to claims 3 and 8, wherein the end part (21) comprises a pulley receiving space bounded by an internal wall of the end part (21), the pulley receiving space being dimensioned such that, when used, the internal wall movement of the flexible element (13) limited to maintain cooperation between the teeth of the pulley (19) and the teeth of the toothed belt.

Lift unit (1) according to any of the preceding claims, wherein the lift unit (1) comprises a blocking member (25) for blocking movement of the counterweight element (11) outside the elongated base (3)