WO2018033868A1

WO2018033868A1 - Bidirectional telescopic guide

Info

Publication number: WO2018033868A1
Application number: PCT/IB2017/054978
Authority: WO
Inventors: Massimo LENTI; Alex DALL'AGNOL
Original assignee: Marangoni Meccanica S.P.A.
Priority date: 2016-08-16
Filing date: 2017-08-16
Publication date: 2018-02-22

Abstract

A bidirectional telescopic guide (1) having a connection bar (2), a first (5) and a second shaft (6) movable in opposite directions with respect to the connection bar (2) in a longitudinal direction (7), a first (10) and a second guide and slide assembly (11) for coupling the first shaft (5) to the connection bar (2) and the second shaft (6) to the first shaft (5), respectively, and a motorized drive (12) for both shafts (5 and 6); the motorized drive being driven by a single motor (38) and having a pair of racks (32 and 33), one solidly connected to a connection bar (2) and the other to the second shaft (6), and both meshing with a single pinion (35) driven by the motor (38) and rotatably mounted on first shaft (5).

Description

"BIDIRECTIONAL TELESCOPIC GUIDE "

TECHNICAL FIELD

The present invention relates to a bidirectional telescopic guide.

BACKGROUND ART

In the field of guides, it is known to use unidirectional telescopic guides with two or more shafts or extensions and bidirectional telescopic guides having a pair of outgoing shafts. The shafts are generally coupled to a single guide and slide with respect to the guide in opposite directions. In some applications, the shafts move freely with respect to the guide and simple mechanical end stops are interposed between the shafts and the guide.

In other applications, each one of the shafts is moved by a respective motor, which can be operated independently of the other motor, or synchronised with the other motor to translate the shafts in opposite directions in unison. Alternatively, the motors are controlled in cascade.

In both cases, an associated cable or belt drive is interposed between each motor and the associated shaft. Normally, electric limit switches are always used in the presence of electric drive motors and, in many cases, braking or parking devices are also provided in predetermined operating positions for the shafts.

In yet other applications, the shafts are driven by a single motor and are coupled to each other and the motor itself, always by cable or belt drives with or without idlers. Braking or parking devices for the shafts may also be provided in these solutions.

Although used, known solutions of the above-described type are not very satisfactory for the following reasons.

First of all, bidirectional telescopic guides always comprise two opposing outgoing shafts. This entails considerable bulk when the guide is completely closed, i.e. in a state of retracted shafts, and relatively limited spans in a condition of maximum opening or extraction of the shafts.

In addition to this, known powered guides of the above- described type are insufficiently precise, both due to the presence of malleable drives, as both belts and cables tend to stretch over time, especially if subjected to variable high loads, in this way losing their initial preloading, and due to positioning errors ascribable to the end stops and/or the inevitable play of the kinematic drive chain. In some solutions, positioning errors of the shafts even vary according to the orientation and/or usage conditions of the guide. In other words, guides designed for working in a horizontal plane are often unsatisfactory or even unsuitable for working in vertical or inclined planes and vice versa.

DISCLOSURE OF INVENTION

The object of the present invention is to provide a bidirectional telescopic guide that allows solving the above-indicated problems in a simple and inexpensive manner and, at the same time, is simple and inexpensive to manufacture and has precise positioning, independently of the conditions of use.

According to the present invention, a bidirectional telescopic guide is provided that comprises a connection bar, a first and a second shaft movable in opposite directions with respect to said connection bar in a longitudinal direction, first guide and slide means for coupling the first shaft to said connection bar, second guide and slide means for coupling said second shaft to said first shaft and a motorized drive for operating said first and second shafts, characterized in that said motorized drive comprises a single motor, a first and a second rack extending parallel to said direction and solidly connected to said connection bar and to said second shaft, respectively, and a pinion simultaneously meshing with both said racks and driven by said motor; said pinion being rotatably mounted on said first shaft.

Preferably, in the above defined guide, the pinion rotates about a fixed axis with respect to the first shaft and orthogonal to said longitudinal direction and to said racks.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described with reference to the accompanying drawings, which illustrate a non-limitative embodiment, in which:

Figure 1 is a perspective view of a preferred embodiment of the guide made according to the principles of the present invention and arranged in a closed position;

Figures 2 and 3 are similar figures to Figure 1 and show the guide according to the invention in two different open positions ;

Figure 4 is an exploded view of the guide in Figure 1; and Figure 5 is a side view of the guide along arrow A in Figure 1.

BEST MODE FOR CARRYING OUT THE INVENTION

In the accompanying figures, reference numeral 1 indicates a powered bidirectional telescopic guide comprising a connection bar 2 having an L-shaped cross-section and designed to be connected, in a known manner, to a connection head 4, fixed or movable and, in any case, in itself known and partially illustrated. Always with reference to the accompanying drawings, the guide 1 also comprises an intermediate extension or shaft 5 and an outer shaft or extension 6 for connecting the load to be handled. Both shafts 5 and 6 are movable in opposite directions with respect to the connection bar 2 along a longitudinal direction 7. Preferably, shaft 5 is defined by an ordinary plate elongated in direction 7. Instead, shaft 6 is defined by an L-shaped section bar.

Referring to Figure 3, the shafts 5 and 6 have lengths L measured parallel to direction 7, equal to each other and also equal to a length LI of the connection bar 2.

Finally, the guide 1 comprises a guide and slide assembly 10 for coupling shaft 5 to the connection bar 2, a guide and slide coupling 11 for coupling shaft 6 to shaft 5 and a motorized mechanical drive 12 for moving the shafts 5 and 6.

Referring to Figures 4 and 5, the assemblies 10 and 11 are conceptually identical. In the particular example described, assembly 10 comprises a pair of shaped sliding bars 13 extending parallel to the direction 7 in positions facing each other, with one solidly connected to the connection bar 2 and the other solidly connected to shaft 5, expediently by screws or other equivalent ways of solid connection. Preferably, the bars 13 have the same length as shaft 5 and the connection bar 2.

Always referring to Figure 3, the guide and slide assembly 10 also comprises a slide 15, in turn, comprising a plate 16 extending in direction 7 and two pairs of sliding shoes 18 and 19. The sliding shoes 18 and 19 are C-shaped, solidly connected to opposite surfaces of the plate 16, extend in opposite directions, and have profiles complementary to those of the bars 13 (Figure 5) to positively couple and slide along the respective bars 13. At their opposite terminal ends, the bars 13 carry respective solidly connected pins 20 defining respective longitudinal stops of the slide 15. Preferably, the pins 20 protrude in a cantilever fashion from the associated sliding bars 13.

Still referring to Figures 4 and 5, the guide and slide assembly 11 comprises a pair of shaped sliding bars 23 extending parallel to direction 7 in positions facing each other, with one solidly connected to shaft 5 and the other solidly connected to shaft 6, expediently by screws or other equivalent ways of solid connection. Preferably, the bars 23 have the same length as the shafts 5 and 6.

Still referring to Figures 4 and 5, assembly 11 also comprises a slide 25, in turn, comprising a plate 26 extending in direction 7 and two pairs of sliding shoes 28 and 29. The sliding shoes 28 and 29 are C-shaped, solidly connected to opposite surfaces of the plate 26, extend in opposite directions, and have profiles complementary to those of the bars 23 (Figure 5) to positively couple and slide along the respective bars 23. At their opposite terminal ends, the bars 23 carry respective solidly connected pins 30 defining respective longitudinal stops of the slide 25. Preferably, the pins 30 protrude in a cantilever fashion from the associated sliding bars 23. Always with reference to the accompanying drawings, the mechanical drive 12 comprises two racks 32 and 33, which extend parallel to said direction 7 in positions facing each other and are solidly connected, respectively, to the connection bar 2 in a position transversely spaced apart from the associated bar 13, and respectively, to shaft 6 in a position transversely spaced apart from the associated bar 23 (Figures 1 and 4) . Preferably, the racks 32 and 33 extend for the entire length of connection bar 2 and of shaft 5, respectively .

Still with reference to Figures 4 and 5, the drive 12 also comprises a pinion 35, which is rotatably mounted on a support frame 36, in turn, solidly connected to an intermediate portion, expediently the middle, of shaft 5. The pinion 35 turns in opposite directions about a rotation axis 37 orthogonal to direction 7, the racks 33 and the shafts 5 and 6 under the driving force of a motor 38, preferably a brushless electric motor, extending coaxially to axis 37 and controlled by a command and control unit 39. In use, by operating the electric motor 38, it is possible to move the shafts 5 and 6 between two opposite open extracted positions, illustrated in Figures 2 and 3, and through an intermediate, closed retracted position, shown in Figure 1. When the shafts 5 and 6 are arranged in the aforementioned extracted positions, the pinion 35 meshes with an end portion of both racks 32 and 33 and both shafts 5 and 6 lie in an extracted end position state. In the closed retracted state, the shafts 5 and 6 fully face each other and shaft 5 fully faces the connection bar 2.

During the passage between one and the other of the aforementioned open extracted positions, the slides 15 and 25 are brought up against the associated pins 20 and 30, moving in unison with the respective shaft 5 and 6.

From the foregoing and that immediately perceivable from Figures 2 and 3, it is clear that the bidirectionality of the guide 1 is obtained by moving both the shafts 5 and 6 in two opposite directions.

In addition to this, it is evident that the length of the guide 1 in the state of maximum opening is double the length of the guide 1 in the closed state, i.e. twice length L. In other words, for a given extension, the described guide 1 is much more compact when arranged in the closed state with respect to known solutions. The special configuration of the guide and slide assemblies 10 and 11 provided, together with the stop pins 20 and 30 enables maintaining the stability of the guide 1 unaltered under load, whatever the distribution of load to be handled and whatever the position the shafts 5 and 6 are in, including the state of maximum extraction of the shafts 5 and 6. The use of a single motor and a double-rack toothed drive enables accurate and precise position control of the shafts 5 and 6 at all times, independently of the load applied, the position of the shafts 5 and 6 with respect to the connection bar 2 and the inclination of the connection bar.

The special drive employed also enables stopping and holding the shafts 5 and 6, and thus the load, in any position along direction 7, as the drive is irreversible. In other words, the described guide 1 does not need braking or parking systems for the shafts 5 and 6.

In the described guide 1, the position control of the shafts 5 and 6 does not require the use of sensors or electric limit switches, as it is sufficient to control the motor 38 for positioning by using a common encoder associated, for example, with the output shaft of the motor.

The position control of the shafts 5 and 6, and therefore of the load, is invariant over time, as, with respect to known solutions, the drive 12 has no malleable or flexible elements, the extensibility of which, as is known, varies over time depending on the magnitude of the load and the frequency of motion reversal. From the foregoing, it is evident that the described guide 1 is capable of working in any operating condition, that is to say whatever the orientation in space of the connection bar 2.

Finally, from the foregoing, it is evident that given the perfect symmetry of the guide 1 with respect to a plane on which direction 7 lies and which passes through shaft 5, the load to be handled could be connected to the connection bar 2 and the connection head 4 connected to shaft 6.

Claims

1. A bidirectional telescopic guide comprising a connection bar, a first and a second shaft moveable in opposite directions with respect to said connection bar in a longitudinal direction, first guide and slide means for coupling the first shaft to said connection bar, second guide and slide means for coupling said second shaft to said first shaft and a motorized drive for operating said first and second shafts, characterized in that said motorized drive comprises a single motor, a first and a second rack extending parallel to said direction and solidly connected to said connection bar and to said second shaft, respectively, and a pinion simultaneously meshing with both said racks and driven by said motor; said pinion being rotatably mounted on said first shaft.

2. The guide according to claim 1, characterized in that said pinion rotates about an axis that is fixed with respect to the first shaft and orthogonal to said longitudinal direction and said racks.

3. The guide according to claims 1 or 2, characterized in that said pinion is rotatably mounted on a middle portion of said first shaft.

4. The guide according to any of the preceding claims, characterized in that said shafts and said connection bar have respective lengths measured parallel to said longitudinal direction that are equal to each other.

5. The guide according to claim 4, characterized in that said first and second shaft are movable between two open extracted positions and an intermediate, closed retracted position; when arranged in said closed retracted position, said shafts are fully facing each other and said first shaft is fully facing said connection bar.

6. The guide according to any of the preceding claims, characterized in that said first and second guide and slide assemblies are equal to each other.

7. The guide according to any of the preceding claims, characterized in that said first and second guide and slide assemblies comprise, respectively, a first and a second slide, interposed between said first shaft and said connection bar and between the first shaft and the second shaft, respectively, and movable both with respect to the shafts and the connection bar; said first and second guide and slide assemblies also respectively comprising first and second sliding guides of the first and said second slide, respectively .

8. The guide according to claim 7, characterized in that said first and second guides are parallel to said sliding direction and comprise a pair of first sliding bars and a pair of second sliding bars, respectively; said first and second bars having the same length as said shafts.

9. The guide according to claim 8, characterized in that said first sliding bars face each other, with one solidly connected to said connection bar and the other solidly connected to said first shaft; said second sliding bars facing each other, with one solidly connected to said first shaft and the other solidly connected to said second shaft.

10. The guide according to claim 9, characterized in that said first and second sliding bars have lengths equal to the length of said shafts.

11. The guide according to claim 7, characterized in that it comprises mechanical strikers fixed to opposite end portions of said shafts and defining longitudinal end stops of said first and second slides.