EP3741720B1

EP3741720B1 - Lift truck

Info

Publication number: EP3741720B1
Application number: EP20175749.9A
Authority: EP
Inventors: Davide Massarenti
Original assignee: LTE Lift Truck Equipment SpA
Current assignee: LTE Lift Truck Equipment SpA
Priority date: 2019-05-24
Filing date: 2020-05-20
Publication date: 2022-03-23
Anticipated expiration: 2040-05-20
Also published as: IT201900007212A1; EP3741720A1

Description

This invention relates to a lift truck.
The lift truck is equipped with an upright designed for lifting and lowering a load.
The upright comprises an actuator unit configured to move an element for supporting the load.
Generally, the actuator unit is in the form of a hydraulic cylinder, preferably of a single action type.
The hydraulic cylinder comprises a jacket which houses a piston, movable by translating inside it, which has a rod having an end positioned outside the jacket.
The piston divides the jacket into a first chamber and a second chamber.
With reference to the arrangement of the hydraulic cylinder in the truck, the longitudinal axis of extension of the cylinder is positioned along a vertical direction, consequently the first chamber is positioned below the second chamber.
The first chamber is configured to receive a liquid fluid, in particular lubricating oil, and the second chamber is configured to receive a gaseous fluid, in particular air from the outside environment.
More specifically, the escape of the rod from the jacket, and therefore the lifting of the supporting element of the load, is regulated by the flow of oil into the first chamber whilst the second chamber is emptied of the air drawn from the outside environment.
On the other hand, the retraction of the rod in the jacket, which corresponds to the lowering of the supporting element of the load, is regulated by the emptying of oil from the first chamber whilst the second chamber fills with air drawn from the outside environment.
The hydraulic cylinder comprises a head element, or cover, for closing the second chamber.
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.
In order to filter the air from the outside environment entering the second chamber during the operation for lowering the supporting element of the load, the head element comprises a filtering element positioned along a conduit for connecting the outside environment and the second chamber for the passage of the air.
As is known, the portion of the conduit which houses the filtering element extends along a direction parallel to the longitudinal axis of extension of the rod, that is, along a vertical direction, so the filtering element is positioned parallel to the rod of the hydraulic cylinder.
More specifically, the filtering element leads out at the face of the head element where the rod comes out.
However, this position of the filtering element lends itself to the accumulation of dust and condensate which is inevitably sucked during the movement of the rod and therefore results in a rapid wear of the inner parts of the hydraulic cylinder.
Moreover, the replacement of the filtering element is a rather difficult operation with the aid of normal tools.
As an example, CN 104 649 198 discloses a lift truck according to the preamble of claim 1.
To overcome these problems, the need has been felt of making a lift truck which comprises an upright device comprising at least one actuator unit configured for moving a supporting element of a respective load from at least a first configuration to a second configuration, different in height from the first configuration, and vice versa.
The actuator unit comprises a plunger slidable in a hollow body, housing the plunger, in such a way as to define a first chamber, configured to receive a liquid fluid, and a second chamber in fluid communication with the outside environment. The hollow body has a longitudinal axis of main extension positioned along a vertical direction.
The actuator unit comprises a head body of the hollow body, forming partly the second chamber, which has at least one conduit extending from a first opening, in fluid communication with the outside environment, to a second opening, in fluid communication with the second chamber.
The conduit of the head body has at least one portion for housing a filtering element.
The housing portion of the filtering element extends along a direction transversal, in particular at right angles, relative to the direction of the axis of the hollow body in such a way that the filtering element is positioned along a direction transversal, in particular at right angles, to the direction of the axis of the hollow body.
Advantageously, the current arrangement of the filtering element allows an easy maintenance using suitable tools, in particular by the expulsion of the filtering element to be replaced acting from the inside towards the outside. Further features and advantages of the invention are more apparent from the non-limiting description which follows of a preferred embodiment of a lift truck as illustrated in the accompanying drawings, in which:

Figure 1 is a schematic perspective view of a lift truck according to this invention;
Figure 2 is a schematic front view of an actuator unit of the lift truck;
Figure 3 is a schematic perspective view of a detail of the actuator unit of Figure 2.

The reference numeral 1 denotes a lift truck according to this invention. The lift truck 1 comprises an upright device 2 configured for lifting and lowering loads.
The upright device 2 comprises an element 3 for supporting a respective load, illustrated for example with the dashed block 4.
The upright device 2 comprises at least one actuator unit 5 configured for moving the supporting element 3 from at least a first configuration to a second configuration, different in height from the first configuration, and vice versa.
For example, the first configuration may correspond to a position for picking up the load 4 from the ground, that is to say, a lowered position, adopted by the supporting element 3 in a loading station.
The second configuration may correspond to a position raised above the ground to be able to move the load 4 received from the loading station to an unloading station.
The actuator unit 5 comprises a plunger 6 slidable in a hollow body 7 housing the plunger 6.
The hollow body 7 has a longitudinal axis 7a of main extension.
In particular, the hollow body 7 is cylindrical in shape.
The hollow body 7 has an outer lateral surface 7b.
The outer lateral surface 7b extends about the main longitudinal axis 7a of extension.
The plunger 6 translates inside the hollow body 7 along the main direction of extension 7a of the hollow body 7.
The plunger 6 defines inside the hollow body 7 a first chamber 8, configured to receive a liquid fluid, and a second chamber 9 in fluid communication with the outside environment.
The first chamber 8 and the second chamber 9 are chambers with a variable volume since the respective volume depends on the relative position of the plunger 6 with respect to the hollow body 7.
The actuator unit 5 is positioned in such a way that the hollow body 7 has the relative main axis 7a of extension positioned in a vertical direction.
In this way, the first chamber 8 is positioned below the second chamber 9. In other words, the first chamber 8 may be defined alternatively as the lower chamber and the second chamber 9 may be defined alternatively as the upper chamber.
The first chamber 8 has at least one inlet and outlet opening for the liquid fluid, in particular oil, not illustrated.
The second chamber 9 has at least one opening 12 for the passage of the gaseous fluid, in particular air coming from the outside environment.
In this embodiment, the opening 12 for the gaseous fluid of the second chamber 9 is both at the inlet and at the outlet.
The actuator unit 5 comprises a rod 13 connected to the plunger 6.
The rod has a relative outer surface 13b.
The rod 13 has at least one end portion 13a positioned outside the hollow body 7.
The rod 13 translates along the main direction of extension 7a of the hollow body 7 by movement of the plunger 6.
In use, the introduction of the liquid fluid into the first chamber 8 makes it possible to translate the plunger 6 upwards, and consequently the rod 13, increasing the volume of the first chamber 8 and, consequently, reducing the volume of the second chamber 9 for the escape of the gaseous fluid, or air, contained therein.
In that way, the actuator unit 5 controls the movement of the supporting element 3 from the first configuration to the second configuration.
On the other hand, the escape of the liquid fluid from the first chamber 8 makes it possible to translate the plunger 6 downwards, and consequently the rod 13, reducing the volume of the first chamber 8 and, consequently, increasing the volume of the second chamber 9 for introducing the gaseous fluid, or air, inside it.
In that way, the actuator unit 5 controls the movement of the supporting element 3 from the second configuration to the first configuration.
The actuator unit 5 comprises a head body 14 of the hollow body 7, defining in part the second chamber 9.
The head body 14 has an outer lateral surface 14a and a top surface 14b. The outer lateral surface 14a of the head body 14 extends about the main axis 7a of longitudinal extension of the hollow body 7.
The top surface 14b of the head body 14 is positioned transversal, in particular at right angles, to the lateral surface 14a.
The outer lateral surface 14a is contiguous with the lateral surface 7b of the hollow body 7.
The head body 14, in particular at its top surface 14b, has a through hole 24 in which the rod 13 slides during its translation.
The head body 14 comprises at least one scraping element 25 and a sealing element 26 configured to come into contact with the outer surface 13b of the rod 13.
The head body 14 has at least one conduit 15 which extends from a first opening 16, in fluid communication with the outside environment, to a second opening 17, in fluid communication with the second chamber 9. The second opening 17 leads into the passageway 12 of the second chamber 9.
According to the invention, the conduit 15 of the head body 14 has at least one portion 27 for housing a filtering element 18.
The filtering element 18 is configured for filtering the gaseous fluid, or air, entering and leaving the second chamber 9.
According to the invention, the housing portion 27 of the filtering element 18 extends along a direction transversal, in particular at right angles, to the direction of the axis 7a of the hollow body 7.
In other words, the housing portion 27 of the filtering element 18 extends along a direction radial to the direction of the axis 7a of the hollow body 7. With reference to the top surface 14b of the head body 14 the housing portion 27 of the filtering element 18 extends parallel to it.
In this way, the filtering element 18 is positioned along a direction transversal, in particular at right angles, to the direction of the axis 7a of the hollow body 7.
In other words, the filtering element 18 is positioned along a direction radial to the direction of the axis 7a of the hollow body 7.
Advantageously, the current arrangement of the filtering element 18 allows an easy maintenance using suitable tools, in particular by the expulsion of the filtering element 18 to be replaced acting from the inside towards the outside.
According to the invention, the actuator unit 5 comprises an element 19 for protecting the first opening 16 of the conduit 15 of the head body 14.
The protective element 19 comprises a lateral portion 22 forming a screen for protecting the first opening 16 of the conduit 15 of the head body 14. The lateral portion 22 has an inner surface 22a facing towards the lateral surface 14a of the head body 14.
The lateral portion 22 has an outer surface 22b facing towards the outside environment.
In other words, the lateral portion 22 of the protective element 19 is in the form of a solid of revolution about the main longitudinal axis 7a of extension.
Advantageously, the protective element 19 defines a physical barrier between the first opening 16 of the conduit 15 of the head body 14 and the outside environment in such a way as to prevent the entrance of contaminating substances which may wear the components of the actuator unit 5.
The protective element 19 and the head body 14 are configured to be coupled to each other.
In particular, the coupling between the protective element 19 and the head body 14 is a sealed coupling.
In particular, a sealing element 23 is positioned between the lateral portion 22 of the protective element 19 and the head body 14.
In particular, the lateral surface 14a of the head body 14 has a respective seat for housing the sealing element 23.
The sealing element 23 is interposed between the lateral surface 14a of the head body 14 and the inner surface 19a of the protective element 19.
According to the invention, the head body 14 has a recess 21, made on the lateral surface of the head body 14, configured for forming a hollow space 20 between the protective element 19 and the first opening 16 of the conduit 15.
The hollow space 20 between the head body 14 and the protective element 19 is in the form of an annular circular crown.
The recess 21 made on the lateral surface of the head body 14 is configured to define a gap 28 for passage of the gaseous fluid, or air of the outside environment, between the lateral surface 14a of the head body 14 and the lateral portion 22 of the protective element 19.
The hollow space 20 is in the form of a groove interposed between the lateral surface 14a of the head body 14 and the lateral portion 22 of the protective element 19.
With reference to the vertical arrangement of the hollow body 7 of the actuator unit 5, the gap 28 allows the passage of the gaseous fluid, or ambient air, from the bottom upwards, if entering the second chamber 9, and from the top downwards, if flowing out from the second chamber 9. The configuration of the protective element 19 and the arrangement of the filtering element 18 in the head body 14 advantageously allows air of the outside environment to be drawn without depositing dust, condensate or other potentially contaminating substances.

Claims

A lift truck comprising an upright device (2) comprising at least one actuator unit (5) configured for moving a supporting element (3) of a respective load (4) from at least a first configuration to a second configuration, different in height from the first configuration, and vice versa; the actuator unit (5) comprises a plunger (6) slidable in a hollow body (7), housing the plunger (6), in such a way as to define a first chamber (8), configured to receive a liquid fluid, and a second chamber (9) in fluid communication with the outside environment; the hollow body (7) having a longitudinal axis (7a) of main extension positioned along a vertical direction;
the actuator unit (5) comprises a head body (14) of the hollow body (7), defining in part the second chamber (9); characterized in that the head body (14) having at least one conduit (15) which extends from a first opening (16), in fluid communication with the outside environment, to a second opening (17), in fluid communication with the second chamber (9);

the conduit (15) of the head body (14) has at least one portion for housing a filtering element (18);

wherein the housing portion of the filtering element (18) extends along a direction transversal, in particular at right angles, relative to the direction of the axis (7a) of the hollow body (7) in such a way that the filtering element (18) is positioned along a direction transversal, in particular at right angles, to the direction of the axis (7a) of the hollow body (7).
The lift truck according to claim 1, characterised in that the actuator unit (5) comprises an element (19) for protecting the first opening (16) of the conduit (15) of the head body (14).
The lift truck according to claim 1 or 2, characterised in that the protective element (19) and the head body (14) are configured to be coupled to each other.
The lift truck according to claim 3, characterised in that it comprises a sealing element (23) positioned between the protective element (19) and the head body (14).
The lift truck according to any one of the preceding claims, characterised in that the head body (14) comprises a recess (21) made on the lateral surface of the head body (14) configured for defining a hollow space (20) for gaseous fluid, or air of the outside environment, between the head body (14) and the protective element (19).
The lift truck according to claim 5, characterised in that the hollow space (20) between the head body (14) and the protective element (19) is in the form of an annular circular crown.
The lift truck according to claim 5, characterised in that the recess (21) made on the lateral surface (14a) of the head body (14) is configured to define a gap (28) for passage of the gaseous fluid, or air of the outside environment, between the lateral surface (14a) of the head body (14) and the lateral portion (22) of the protective element (19).