WO2025219942A1

WO2025219942A1 - Upright of an industrial vehicle

Info

Publication number: WO2025219942A1
Application number: PCT/IB2025/054069
Authority: WO
Inventors: Davide Massarenti; Giovanni Paolo Bonelli
Original assignee: LTE Lift Truck Equipment SpA
Current assignee: LTE Lift Truck Equipment SpA
Priority date: 2024-04-18
Filing date: 2025-04-17
Publication date: 2025-10-23
Anticipated expiration: 2026-10-18

Abstract

Described is an upright of an industrial vehicle comprising a fixed section (3) and a section (4) movable, relative to the fixed section (3), along an upwards and downwards vertical direction; at least one hydraulic cylinder (5) performs the movement of part of the movable section (4) relative to the fixed section (3); the hydraulic cylinder (5) comprises a jacket (6) for housing a piston (7), movable inside the jacket (6); the piston (7) divides the jacket (6) into a first chamber (10) and into a second chamber (11) whose respective volume varies in relation to the relative position of the piston (7) in the jacket (6); a rod (8) is connected to the piston (7) and defines therewith an element (9) which is movable relative to the jacket (6); the movable element (9) has an inner chamber (15) which extends along at least part of the length of the rod (8) and of the piston (7) and has at least one conduit (16) which places the inner chamber (15) in fluid communication with the first chamber (10) of the jacket (6).

Description

DESCRIPTION

UPRIGHT OF AN INDUSTRIAL VEHICLE

Technical field

This invention relates to an upright of an industrial vehicle.

Background art

The industrial vehicle is, for example, a lift truck, in particular with forks, or another vehicle designed for moving and transporting goods.

The upright has a fixed section and a section movable, relative to the fixed section, for moving a load upwards and downwards.

The movable section comprises a unit for gripping a load.

With regard to the type of upright, a single hydraulic cylinder or a pair of hydraulic cylinders performs the movement of the gripping unit.

These cylinders are identified in technical jargon as primary cylinders.

Prior art primary cylinders comprise a rod equipped with a piston movable inside a jacket.

The piston forms two chambers separate from each other, a first chamber and a second chamber, in which an operating fluid (hydraulic fluid or hydraulic liquid) circulates.

The chambers modify the respective volume in relation to the translation of the piston in the jacket.

In a retracted position of the rod of the hydraulic cylinder, the piston is in a first end of stroke position in which the volume of the first chamber is a maximum and the volume of the second chamber is a minimum.

In an extended position of the rod of the hydraulic cylinder, the piston is in a second end of stroke position in which the volume of the first chamber is a minimum and the volume of the second chamber is a maximum.

One of the ends of the rod comes out of the jacket at the first chamber and a head element, or cover, closes the first chamber for the passage and guiding of the rod. The head element comprises one or more sealing elements and scraping elements configured to come into contact with the outer surface of the rod during its translation, entering and exiting the first chamber.

The head element has a conduit in communication with the outside environment and with the first chamber of the jacket.

A filtering element is inserted in the conduit for filtering the air from the outside environment entering the first chamber during the lowering operation.

However, this route of communication with the outside environment causes the formation of rust inside the jacket of the cylinder.

This results in an unacceptable operating condition which requires a different design solution to avoid this problem.

There are prior art hydraulic cylinders with an oil bath which do not suffer from the formation of rust; this solution is generally adopted for the so- called secondary cylinders which move profiles of the movable section relative to the fixed section.

This oil bath solution is difficult to use for the primary cylinders due to the overall size greater than that of other solutions, with consequent problems in terms of visibility of the driver.

Aim of the invention

In order to overcome this problem, a hydraulic cylinder has been conceived wherein the above-mentioned first chamber, closed by the head element or cover, is sealed relative to the second chamber.

The operating fluid is mixed with the air in the first chamber.

Considering this embodiment, the need has been felt of making an upright of an industrial vehicle as described in independent claim 1 wherein the operating fluid, upon reaching an end of stroke position of the piston, can flow from the chamber of the jacket to the inner chamber of the rod and of the piston through a conduit made only in the piston. In this solution claimed, at the piston end of stroke position, the conduit remains in fluid communication with the first chamber without being occluded.

Brief description of the drawings

Further features and advantages of the invention are more apparent from the non-limiting description which follows of a preferred embodiment of an upright of an industrial vehicle as illustrated in the accompanying drawings, in which:

- Figure 1 is a schematic perspective view of an industrial vehicle provided with an upright in accordance with this invention;

- Figure 2 is a schematic cross-section of a first embodiment of a hydraulic cylinder of the upright of Figure 1 in a first configuration wherein the rod is in a retracted position;

- Figure 3 shows the hydraulic cylinder of Figure 2 in a second configuration with the rod in a partly withdrawn position;

- Figure 4 is an enlarged view of a detail of the hydraulic cylinder of Figure 2 and Figure 3;

- Figure 5 is a schematic cross-section of a second embodiment of the hydraulic cylinder of the upright of Figure 1 ;

- Figure 6 is an enlarged view of a detail of the hydraulic cylinder of Figure 5;

- Figure 7 shows a variant embodiment of Figure 5;

- Figure 8 is a schematic cross-section of a third embodiment of the hydraulic cylinder of the upright of Figure 1 ;

- Figure 9 shows a variant embodiment of Figure 8;

- Figure 10 shows an enlarged detail of the hydraulic cylinder of Figure

2 in a third configuration in which the rod is in a completely withdrawn position;

- Figures 11 and 12 illustrate two variant embodiments of the detail of Figure 10. Detailed description of preferred embodiments of the invention

The numeral 1 denotes an upright of an industrial vehicle 2, see Figure 1 .

The industrial vehicle 2 is a vehicle suitable for transporting loads, such as, for example, a lift truck.

The upright 1 comprises a fixed section 3 and a section 4 movable, relative to the fixed section 3, along an upwards and downwards vertical direction relative to the ground.

The fixed section 3 comprises a single pair of sliding members 3a.

The movable section 4 comprises one or more pairs of sliding members 4a.

If the movable section 4 comprises several pairs of sliding members 4a, these pairs are movable relative to each other in a telescopic fashion.

The movable section 4 comprises a unit 19 for gripping a load.

The gripping unit 19 is movable relative to at least one pair of sliding members 4a of the movable section 4.

With regard to the type of upright 1 , a single hydraulic cylinder 5 or a pair of hydraulic cylinders 5 performs the movement of part of the mobile section 4 relative to the fixed section 3, in particular the movement of the gripping unit 19.

With reference to a hydraulic cylinder 5, it has a main direction of extension D.

The direction D is parallel to the vertical.

The hydraulic cylinder 5 comprises a jacket 6 for housing a piston 7, movable inside the jacket 6.

A rod 8 is connected to the piston 7 and is moved by the piston 7.

The piston 7 and the rod 8 define an element 9 which is movable relative to the jacket 6.

The rod 8 has on its outer surface an elastic ring 27.

The positioning of the elastic ring 27 along the rod 8 is determined by the maximum desired stroke of the rod 8 and/or by the overall dimensions of the hydraulic cylinder 5. This arrangement determines a relative positioning of the elastic ring 27 relative to the piston 7.

The piston 7 divides the jacket 6 into a first chamber 10 and into a second chamber 11 whose respective volume varies in relation to the relative position of the piston 7 in the jacket 6.

The first chamber 10 is closed by a lid 12 connected to one of the ends of the jacket 6.

The cover 12 closes in a sealed fashion the end of the jacket 6, meaning that the first chamber 10 is closed and isolated from the outside environment.

Inside the first chamber 10 there is a predetermined quantity of operating fluid, that is, lubricating liquid, labelled 25.

The elastic ring 27 is intended to make contact with the cover 12 defining the end of stroke of the movable element 9.

As stated above, this determines the maximum withdrawal of the rod 8.

The cover 12 has a through hole 20 in which a portion of the rod 8 is inserted.

At least one sealing element 21 and a scraper 22 are interposed between the outer surface of the rod 8 and the through hole 20 of the cover 12.

A guide element 26, in the form of a ring, is interposed between the outer surface of the rod 8 and the through hole 20 of the cover 12.

The second chamber 11 is in fluid communication with a conduit 13 for introducing a working fluid.

Thus, when the operating fluid is fed into the second chamber 11 , the piston 7 is moved into the jacket 6, thereby increasing the volume of the second chamber 11 and hence reducing the volume of the first chamber 10 (Figure 3).

In other words, with reference to the vertical direction, the piston 7 translates from the bottom upwards, a raising operation.

The raising operation concludes with the reaching of the piston 7 in an end of stroke position, or third configuration, determined by the contact between the elastic ring 27 and part of the hole 20 passing through the cover 12 (Figure 10).

Alternatively, as illustrated in Figures 11 and 12, the end of stroke position is determined by a contact between the piston 7 and the cover 12.

According to these variant embodiments the elastic ring 27 is not present.

It should be noted that in the end of stroke position illustrated in all the variant embodiments (Figures 10, 11 and 12), or third configuration, the conduit 16 which places the inner chamber 15 in fluid communication and the first chamber 10 of the jacket 6 remains in fluid communication with the first chamber 10 without being occluded.

This is because the conduit 16 has no braking function of the movable element 9.

The second chamber 11 is in fluid communication with a conduit 14 for emitting a working fluid.

The infeed duct 13 and the emission conduit 14 coincide since the hydraulic cylinder 5 is a single-acting cylinder.

In this way, the escape of the operating fluid from the second chamber 11 moves the piston 7 during its translation into the jacket 6, increasing the volume of the first chamber 10 and, therefore, reducing the volume of the second chamber 11 (Figure 2).

In other words, with reference to the vertical direction, the piston 7 translates from the top downwards, a lowering operation.

In order to allow the piston 7 to translate from the bottom upwards, thereby reducing the volume of the first chamber 10, the movable element 9 has an inner chamber 15 which extends along at least part of the length of the rod 8 and/or of the piston 7 and at least one conduit 16 in fluid communication with the inner chamber 15 and the first chamber 10 of the jacket 6.

Advantageously, the operating fluid with the reduction in the inner space of the first chamber 10 can flow into the inner chamber 15 of the movable element 9 through the conduit 16 which places in communication the first chamber 10 of the jacket 6 with the inner chamber 15.

This prevents the operating fluid mixed with air from obstructing the translation of the piston 7 with the increase in the volume of the second chamber 11 during the raising operation, since the fluid is incompressible.

During the lowering operation, with the increase in the volume of the first chamber 10, the operating fluid introduced into the inner chamber 15 of the movable element 9 is free to return into the first chamber 10 through the conduit 16 which places it in communication with it.

The inner chamber 15 extends along at least part of the length of the rod 8 and along at least part of the length of the piston 7.

The term length means a linear extension along a direction parallel to the main direction of extension D of the hydraulic cylinder 5.

According to the variant embodiments of Figures 2 to 4, with reference to the rod 8 the inner chamber 15 extends for a limited portion of the rod 8. The inner chamber 15 formed in the rod 8 is a blind chamber.

According to the variant embodiment of Figures 8 and 9, the inner chamber 15 extends along the entire length of the rod 8.

According to this variant embodiment, the rod 8 is in the form of a tubular body (Figures 8 and 9).

According to this embodiment, the rod 8 comprises an element 23 for closing one of the ends of the rod 8.

The closing element 23 is positioned at the end of the rod 8 opposite the piston 7.

The piston 7 is connected to the rod 8 on the opposite side to the closing element 23.

The conduit 16 which places in communication the inner chamber 15 and the first chamber 10 of the jacket 6 is formed in the piston 7.

According to the embodiments illustrated, the conduit 16 is formed only in the piston 7. The conduit 16 which places in communication the inner chamber 15 and the first chamber 10 of the jacket 6 has at least one stretch T1 which extends in a direction transversal to the main direction of extension D of the hydraulic cylinder 5, see detail in Figure 2.

Preferably, the direction of T1 is at a right angle to the direction D (Figure 4).

According to an alternative embodiment, see detail in Figure 3, the conduit 16 has at least one stretch T1 which extends in a direction transversal or orthogonal to the main direction of extension D of the hydraulic cylinder 5 and at least one further stretch T2 which extends in a direction converging or parallel to the main direction of extension D of the hydraulic cylinder 5 (Figure 6).

This further stretch T2 leads into the first chamber 10.

Optionally, there are valve means 17 housed in a conduit 24 in fluid communication with the inner chamber 15 (they are absent in the embodiments of Figure 7 and Figure 8).

The valve means 17 are configured to pass from a closed position to an open position of the conduit 24 if the pressure inside the conduit 24 in which they are installed exceeds a threshold value.

An overpressure condition might occur when the piston 7 reaches the end of stroke position during the raising operation wherein the first chamber 10 reaches a condition of minimum volume and the second chamber 11 reaches a condition of maximum volume, as illustrated in Figure 2.

The valve means 17 are in fluid communication with the second chamber 11 in such a way that when they are in the open position the fluid can flow from the inner chamber 15 to the second chamber 11 .

In order to facilitate the passage of fluid in the valve means 17, optionally, a drainage body 18 (illustrated in Figure 5 and in Figure 9) has one end leading into the inner chamber 15 and the other end in fluid communication with the valve means 17. The size of the drainage body 18 depends on the quantity of hydraulic fluid present under normal operating conditions in the first chamber 10.

If, over time, a leak of hydraulic fluid occurs from the second chamber 11 to the first chamber 10, there will be a greater quantity of hydraulic fluid in the first chamber 10 which could result in an overpressure condition which brings the valve means 17 to the open position.

The invention also relates to an industrial vehicle 2, in particular a lift truck, comprising an upright according to the invention.

It should also be noted that the combination of alternative embodiments with reference to the shape of the inner chamber 15, the shape of the conduit 16 which places in communication the inner chamber 15 and the first chamber 10 of the jacket 6, the presence/absence of the valve means 17 and the presence/absence of the drainage body 18 is not limited to the embodiments illustrated since it is possible to combine these features while remaining within the innovative concept of this invention.

Lastly, it should be noted that since the jacket 6 is not exposed to air entering from the outside, since the cover 12 closes the first chamber 10 without placing it in communication with the outside environment, rust does not form in the jacket 6.

Claims

1 . An upright of an industrial vehicle comprising a fixed section (3) and a section (4) movable, relative to the fixed section (3), along an upwards and downwards vertical direction; the movable section (4) comprises at least one pair of sliding members (4a) movable relative to the fixed section (3); the movable section (4) comprises a unit (19) for gripping a load which is movable relative to the pair of sliding members (4a) of the movable section (4); at least one hydraulic cylinder (5) performs the movement of the gripping unit (19) and/or the pair of sliding members (4a); the hydraulic cylinder (5), has a main direction of extension (D), comprises a jacket (6) for housing a piston (7), movable inside the jacket (6); the piston (7) divides the jacket (6) into a first chamber (10) and into a second chamber (11 ) whose respective volume varies in relation to the relative position of the piston (7) in the jacket (6); the first chamber (10) is closed by a lid (12) connected to one of the ends of the jacket (6); the second chamber (11 ) is in fluid communication with a conduit (13, 14) for introducing and emitting a working fluid; a rod (8) is connected to the piston (7) and defines therewith an element (9) which is movable relative to the jacket (6); the piston (7) is movable from a first position, corresponding to a retracted position of the rod (8), to a second end of stroke position, corresponding to an extended position of the rod (8), and vice versa; at least one end of the rod (8) extends outside the jacket (6) through the lid (12); the movable element (9) has an inner chamber (15) which extends along at least part of the length of the rod (8) and of the piston (7) and has at least one conduit (16) which places the inner chamber (15) in fluid communication with the first chamber (10) of the jacket (6). characterised in that the conduit (16) which places in fluid communication the inner chamber (15) and the first chamber (10) of the jacket (6) is formed only in the piston

(7) and in that, at the second end-of-stroke position of the piston (7), the conduit (16) remains in fluid communication with the first chamber (10) without being occluded.

2. The upright according to the preceding claim, characterised in that the inner chamber (15) extends along at least part of the length of the rod

(8) and along at least part of the length of the piston (7).

3. The upright according to any one of the preceding claims, characterised in that the conduit (16) which places in fluid communication the inner chamber (15) and the first chamber (10) of the jacket (6) has at least one stretch (T1 ) which extends in a direction transversal, preferably orthogonal, to the main direction of extension (D) of the hydraulic cylinder (5).

4. The upright according to the preceding claim, characterised in that the conduit (16) has at least one stretch (T1 ) which extends in a direction transversal, preferably orthogonal, to the main direction of extension (D) of the hydraulic cylinder (5) and at least one further stretch (T2) which extends in a direction converging or parallel to the direction of extension (D) of the hydraulic cylinder (5); this further stretch (T2) leads into the first chamber (10).

5. The upright according to any one of the preceding claims, characterised in that the movable element (9) comprises valve means (17) housed in at least part of a conduit (24) in fluid communication with the inner chamber (15); the valve means (17) are configured to pass from a closed position to an open position of the conduit (24) if the pressure inside the conduit (24) exceeds a threshold value.

6. The upright according to the preceding claim, characterised in that it comprises a drainage body (18) having one end opening into the inner chamber (15) and one end in communication with the valve means (17).

7. The upright according to any one of the preceding claims, characterised in that the inner chamber (15) extends along the entire length of the rod (8).

8. The upright according to the preceding claim, characterised in that the rod (8) comprises an element (23) for closing the end of the rod (8) which extends outside the jacket (6); the piston (7) is connected to the rod (8) on the opposite side to the closing element (23).

9. The upright according to any one of the preceding claims, characterised in that the rod (8) has on its outer surface an elastic ring (27) intended to make contact with the cover (12) defining the second end of stroke position of the piston (7).

10. The upright according to any of claims 1 to 8, characterised in that the second end of stroke position of the piston (7) is determined by a contact between the piston (7) and the cover (12).

11 . The upright according to any one of the preceding claims, characterised in that the rod (8) does not have any hole which places the inner chamber (15) in direct communication with the first chamber (10) of the jacket (6).

12. An industrial vehicle, in particular a lift truck, comprising an upright according to any one of claims 1 to 11 .