WO2024252088A1 - Improved architecture of an electrohydraulic excavator - Google Patents

Abstract

The invention relates to an architecture of an electric excavator (1), comprising: a lower frame (10) comprising movement members (12) that are capable of moving the electric excavator, and at least one movable accessory (14) capable of being actuated by at least one hydraulic cylinder (15); at least one hydraulic circuit (16) capable of supplying the hydraulic cylinder (15) of the lower frame (10); and an upper frame (20) comprising at least one electric energy storage means (22) and a controller (24), the upper frame (20) being rotatable in relation to the lower frame (10) via a rotary collector (30), the hydraulic circuit (16) being arranged entirely inside the lower frame (10).

Description

IMPROVED ELECTROHYDRAULIC SHOVEL ARCHITECTURE

Description

Technical Domain

[0001] The present invention relates to the field of electric machines, more precisely an electric mini excavator architecture comprising hydraulic components.

Previous technique

[0002] Small electric shovels, not exceeding 5 or 6 tonnes for example, are frequently used for work not requiring high outputs and limited to small areas. In a known manner, these mini shovels comprise an upper chassis including a turret and an articulated arm, and being rotatable relative to a lower chassis including tracks for the translational movement of the machine, as well as a stabilization and leveling blade, allowing on the one hand to level the ground when the machine is moving, and on the other hand to stabilize the latter when stationary, by pressing the blade on the ground. Similarly, there may be a track width adjustment cylinder, which allows the tracks to be spread apart or brought together.

[0003] In small electric excavators, the power source, including a battery, is generally installed in the upper chassis, and the functions of the lower chassis, including the drive of the tracks and the stabilizing blade, use hydraulic actuators. Furthermore, the constant increase in the electrification of such machines involves issues such as the sizing of the batteries and the space available for the electrical equipment.

[0004] Furthermore, the rotation of the turret relative to the lower chassis implies the presence of a rotating joint for the fluids and a rotating collector for the electrical part. The rotating joint thus makes it possible to transmit the fluids from the upper chassis to the lower chassis, up to the hydraulic actuators. [0005] However, the actuators for driving the tracks are far from the flow source that supplies them. This implies a reduction in energy efficiency, which leads to a significant loss of power during long travel on a construction site. These losses are due to the fact that the flow of fluid pumped into the upper chassis passes successively through distributors, into the rotating joint, then into the hoses to the supply and discharge ports of the engines. Since the discharge flow follows approximately the same path to the tank, the losses are almost doubled. In particular, hydraulic rotating joints induce high losses due to fluid lamination.

[0006] Thus, existing electric shovel architectures do not provide optimal performance, and the hydraulic and/or electrical rotating connections used elsewhere on these machines are complex, bulky and expensive.

[0007] The present invention thus aims to respond at least partially to these problems.

Disclosure of the invention

[0008] The present disclosure relates to an electric shovel architecture, comprising:

- a lower chassis comprising movement members capable of moving the electric shovel, and at least one mobile accessory capable of being actuated by at least one hydraulic cylinder,

- at least one hydraulic circuit capable of supplying the hydraulic cylinder of the lower chassis,

- an upper chassis comprising at least one means for storing electrical energy and a controller, the upper chassis being rotatable relative to the lower chassis by means of a rotating collector, the hydraulic circuit being arranged entirely in the lower chassis.

[0009] Arranging the hydraulic circuit entirely in the lower chassis makes it possible, on the one hand, to limit losses linked to the path of the fluid from the upper chassis to the lower chassis, thereby improving the efficiency of the machine, and on the other hand to simplify the rotating connection (here the rotating collector) between the upper chassis and the lower chassis.

[0010] In some embodiments, the hydraulic circuit comprises a reservoir, a motor pump unit having a hydraulic pump and an electric motor adapted to rotate the hydraulic pump, at least one hydraulic conduit and an integrated control adapted to actuate the hydraulic cylinder to move or immobilize the mobile accessory.

[0011] In some embodiments, the reservoir is formed by at least part of a housing of the lower chassis, the motor pump unit being disposed in the reservoir.

[0012] In some embodiments, the rotating collector is capable of transferring only the current supplied by the electrical energy storage means and the commands issued by the controller, from the upper chassis to the lower chassis.

[0013] In some embodiments, the rotating manifold does not include any fluid passage between the upper frame and the lower frame.

[0014] In some embodiments, each movement member is actuated by an electric motor capable of executing commands transmitted by the controller.

[0015] In some embodiments, the electric motor of each movement member comprises a brake controlled by the controller and a variator capable of converting a direct current coming from the electrical energy storage means into an alternating current.

[0016] In some embodiments, the electric motor of each movement member is a geared motor.

[0017] In some embodiments, the electric motor of each movement member is capable of being cooled by a fluid circulating in the hydraulic circuit. [0018] In some embodiments, the architecture includes a heat exchanger capable of cooling a fluid circulating in the hydraulic circuit, the heat exchanger comprising a portion of the lower frame.

[0019] In some embodiments, the moving members are tracks, and the movable accessory is a leveling and stabilizing blade.

[0020] In some embodiments, the mobile accessory comprises at least one of the movement members, the at least one hydraulic cylinder being capable of moving the at least one of the movement members to move the movement members closer to or further away from each other.

Brief description of the drawings

[0021] The invention and its advantages will be better understood upon reading the detailed description given below of different embodiments of the invention given as non-limiting examples. This description refers to the appended pages of figures, in which:

[0022] [Fig. 1] Figure 1 schematically represents, in a side view, an architecture of an electric mini excavator according to an embodiment of the invention.

[0023] [Fig. 2] Figure 2 schematically represents, in a rear view, the electric mini excavator of Figure 1.

[0024] [Fig.3] Figure 3 is a detailed schematic representation of the architecture of the electric mini excavator of Figures 1 and 2.

Description of the embodiments

[0025] Figures 1 and 2 respectively represent a side and rear view of an electric mini excavator architecture 1 according to the invention, and Figure 3 schematically illustrates this architecture in detail.

[0026] The electric mini excavator 1 comprises a lower chassis 10 and an upper chassis 20 movable in rotation about an axis A vertical relative to the lower chassis 10, by means of a connection, comprising a rotating collector 30. More precisely, the connection between the upper and lower chassis ensures several functions, including a bearing function performed by a circular roller or ball track, an orientation function by a toothed crown and a rotation motor capable of providing a rotational torque, and a rotating joint function via the rotating collector 30 to transmit energy and a logic control signal (or fluids according to the prior art). Alternatively, the logic signal can be transmitted by a radio signal. Alternatively, it could be transmitted in the power signal which would serve as a carrier wave.

[0027] The term "lower chassis" means the entire lower part of the shovel 1, in other words the lower carriage, including the structure itself of the chassis, and the elements carried by this structure. Thus, the lower chassis 10 comprises a casing 17 carrying two movement members, typically tracks 12. A front end of the casing 17 carries a mobile accessory, typically a stabilizing and leveling blade 14 (hereinafter referred to as "blade 14"), capable of leveling the ground when the shovel 1 is moving, and of stabilizing the shovel 1 when stationary, by pressing the blade 14 on the ground. The blade 14 can be actuated by a hydraulic cylinder 15 making it possible to adjust the position of the blade 14. Alternatively, the shovel 1 can comprise at least two hydraulic cylinders 15 allowing at least two hydraulic movements of the blade 14.

[0028] The upper chassis 20 comprises a turret inside which a user can sit to operate the shovel 1. A front face of the turret carries an articulated arm 26 at the end of which is arranged a tool, for example a bucket. Such an articulated arm 26, well known, is not the subject of the invention and will not be described in more detail.

[0029] The upper chassis 20 further comprises an electrical energy storage means, typically a battery 22 capable of providing a direct current (DC current), and a controller 24, typically a computer or an electronic control unit commonly referred to by the acronym ECU in English. The controller 24 is adapted to control the various electrical components arranged in the lower chassis 10, each component electrical system which may include a variator to shape the current according to the instructions of the controller, in the manner described below.

[0030] In this regard, the lower chassis 10 further comprises a hydraulic circuit 16 capable of actuating the hydraulic cylinder 15. The hydraulic circuit 16 comprises a reservoir R containing a hydraulic fluid, for example oil, a motor pump unit including an electric motor M and a hydraulic pump 162 driven in rotation by the electric motor M, hydraulic conduits 161 inside which the fluid coming from the reservoir R circulates, and a control (not shown) making it possible to actuate the hydraulic cylinder 15 to move or immobilize the blade 14.

[0031] Thus, the hydraulic circuit 16 is arranged entirely in the lower chassis 10. In other words, the elements that comprise the hydraulic circuit 16, namely the reservoir R, the conduits 161, the hydraulic pump 162, the electric motor M and the control are all arranged in the lower chassis 10. It is thus understood that no hydraulic circuit is arranged in both the upper chassis 20 and the lower chassis 10, and therefore that the rotating collector 30 does not accommodate any passage of fluid between the upper chassis 20 and the lower chassis 10.

[0032] It will be noted that the upper chassis 20 can also comprise a hydraulic circuit, for example to actuate the articulated arm 26, but this hydraulic circuit is then arranged entirely in the upper chassis 20 and does not communicate with the lower chassis 10.

[0033] This configuration makes it possible to limit the pressure losses linked to the flow of fluid from the upper chassis 20 to the lower chassis 10 when the tank is arranged in the upper chassis 20, and also to the return of the fluid to said tank. This thus makes it possible to improve the overall efficiency of the shovel 1 when the hydraulic actuators are actuated, and consequently to increase the autonomy of the battery 22 which electrically supplies the engine M. In this way, the shovel can work for longer. [0034] Furthermore, no fluid passage is necessary via the rotating collector 30, which is capable of transferring only the current supplied by the battery 22 and the commands issued by the controller 24, from the upper chassis 20 to the lower chassis 10. The rotating collector 30 is thus simpler, less bulky, and less expensive.

[0035] Alternatively, the reservoir R is not a separate element arranged in the lower chassis 10, but is formed by a portion of the casing 17 itself. The casing 17 may also be composed of a hollow structural element of the chassis 10. The motor pump unit may then be arranged in the reservoir.

[0036] The lower chassis 10 further comprises electric motors, typically geared motors 18 comprising an electric motor accompanied by a mechanical reducer, capable of actuating the tracks 12. More precisely, the architecture comprises as many geared motors as there are movement members, in the present case two geared motors 18, that is to say one geared motor 18 for each track 12.

[0037] Each geared motor 18 comprises a variator (or inverter) 181 capable of converting a direct current (DC current) coming from the battery 22 into an alternating current (AC current), and a brake 182 capable of applying a braking torque to the geared motor 18 to slow down and immobilize the track 12 and therefore the shovel 1.

[0038] The variator 181 is connected to the battery 22 via a connector 23 passing through the rotating collector 30. Thus, only direct current passes through the rotating collector 30, the direct current being converted into alternating current in the lower chassis 10 only, by the variator 181. This makes it possible to further simplify the rotating collector 30.

[0039] The brake 182 is controlled by the controller 24 via a wired connection, or even wirelessly as shown in FIG. 3. More generally, the controller 24 is able to transmit control signals (for example “CAN bus” signals) to the lower chassis 10, with or without contacts (the “contactless” configuration is shown in FIG. 3), in particular to the geared motors 18 to control the translation and direction of the shovel 1 or to apply a brake, or to the electric motor M to regulate the flow rate of the hydraulic pump 162. More precisely, by "contactless", it is understood that the logic control signals are transmitted for example by radio waves, and are therefore not transmitted via a physical link passing through the rotating collector 30. Conversely, by "with contact", it is understood that the logic control signals are transmitted via the rotating collector 30, either by dedicated tracks or by a carrier wave of the electrical power signal.

[0040] Using a geared motor 18 for each track 12, integrating its own brake, its own variator and its control logic makes it possible to simplify the lower chassis. The geared motor 18 can in fact be controlled simply remotely by the controller 24, and does not require hydraulic actuators powered from the upper chassis 20.

[0041] Alternatively, the tracks 12 can be driven hydraulically via an associated hydraulic circuit. In this case, said hydraulic circuit is arranged entirely in the lower chassis.

[0042] Preferably, the electric shovel architecture 1 comprises a cooling circuit for cooling the geared motors 18. In the embodiment shown schematically in FIG. 3 , the cooling fluid for the electric geared motors 18 is the hydraulic oil of the hydraulic circuit 16. In particular, the fluid taken from the reservoir R by the hydraulic pump 162 can be routed to a distribution device 163 adapted to distribute the fluid between the cylinder 15 and the geared motors 18, in particular by taking a pilot pressure allowing the piloting of the hydraulic cylinder 15 and therefore of the blade 14, the remainder of the hydraulic fluid being routed to the geared motors 18, in contact with which cooling by heat transfer takes place, to cool the latter. The hydraulic fluid is then redirected to the reservoir R.

[0043] Using the fluid and the pump 162 of the hydraulic circuit 16 to both control the cylinder 15 and allow the cooling of the geared motors 18 makes it possible to further simplify the architecture of the electric shovel 1. [0044] Preferably, the hydraulic circuit 16 may further comprise a heat exchanger 164 on the hydraulic channels 161 redirecting the hydraulic fluid to the reservoir R, making it possible to cool the hydraulic fluid circulating in the hydraulic channels 161, in order to improve the cooling of the geared motors 18. When the reservoir R is formed by a portion of the casing 17 of the lower chassis 10, the heat exchanger may be formed by the wall of the casing 17 itself, the inertia of the lower chassis 10 and/or the ambient air on the outside of the casing 17 then allowing the fluid to be cooled. Preferably, the hydraulic circuit 16 may further comprise a filter 165, on the hydraulic sampling channel 161, upstream of the pump 162 for example. Alternatively, the filter 165 may be arranged downstream of the exchanger 164.

[0045] It will be noted that instead of a stabilizing blade, the architecture can comprise a hydraulic cylinder (not shown) capable of laterally moving the tracks 12 closer or further apart from each other, in order to adjust the track width. This allows access to the worksite through narrow passages, and to adjust the spacing of the tracks to the maximum width permitted by the track, ensuring the lateral stability of the machine. Alternatively, the architecture can comprise a first hydraulic cylinder, typically for a stabilizing blade as described above, and a second hydraulic cylinder for adjusting the track width. The hydraulic circuit 16 can thus actuate both the first cylinder and the second cylinder, and also allows the geared motors 18 to be cooled.

[0046] It will also be noted that the functions described above (stabilizing blade 14 and track width adjustment) supplied by the hydraulic circuit 16 and actuated by hydraulic cylinders are not limiting, the hydraulic circuit 16 being able to supply other functions and other mobile accessories of the lower chassis 10.

[0047] Although the present invention has been described with reference to specific exemplary embodiments, it is obvious that modifications and changes may be made to these examples without departing from the general scope of the invention as defined by the claims. In particular, Individual features of the various illustrated/mentioned embodiments may be combined in additional embodiments. Therefore, the description and drawings are to be considered in an illustrative rather than restrictive sense.

Claims

Claims [Claim 1] Electric shovel architecture (1), comprising: - a lower chassis (10) comprising movement members (12) capable of moving the electric shovel, and at least one mobile accessory (14) capable of being actuated by at least one hydraulic cylinder (15), - at least one hydraulic circuit (16) capable of supplying the hydraulic cylinder (15) of the lower chassis (10), - an upper chassis (20) comprising at least one electrical energy storage means (22) and a controller (24), the upper chassis (20) being rotatable relative to the lower chassis (10) by means of a rotating collector (30), characterized in that the hydraulic circuit (16) is arranged entirely in the lower chassis (10). [Claim 2] Architecture according to claim 1, in which the hydraulic circuit (16) comprises a reservoir (R), a motor pump unit having a hydraulic pump (162) and an electric motor (M) adapted to drive the hydraulic pump (162) in rotation, at least one hydraulic conduit (161) and an integrated control adapted to actuate the hydraulic cylinder (15) to move or immobilize the mobile accessory (14). [Claim 3] Architecture according to claim 2, in which the tank (R) is formed by at least part of a casing (17) of the lower chassis (10), the motor pump unit being arranged in the tank (R). [Claim 4] Architecture according to any one of claims 1 to 3, in which the rotating collector (30) is capable of transferring only the current supplied by the electrical energy storage means (22) and the commands issued by the controller (24), from the upper chassis (20) to the lower chassis (10). [Claim 5] Architecture according to any one of claims 1 to 4, in which the rotating collector (30) does not include any fluid passage between the upper frame (20) and the lower frame (10). [Claim 6] Architecture according to any one of claims 1 to 5, in which each displacement member (12) is actuated by an electric motor (18) capable of executing commands transmitted by the controller (24). [Claim 7] Architecture according to claim 6, in which the electric motor (18) of each displacement member (12) comprises a brake (182) controlled by the controller (24) and a variator (181) capable of converting a direct current coming from the electrical energy storage means (22) into an alternating current. [Claim 8] Architecture according to claim 6 or 7, in which the electric motor (18) of each displacement member (12) is a geared motor. [Claim 9] Architecture according to any one of claims 6 to 8, in which the electric motor (18) of each displacement member (12) is capable of being cooled by a fluid circulating in the hydraulic circuit (16). [Claim 10] Architecture according to any one of claims 1 to 9, comprising a heat exchanger (164) capable of cooling a fluid circulating in the hydraulic circuit (16), the heat exchanger (164) comprising a portion of the lower chassis (10). [Claim 11] Architecture according to any one of claims 1 to 10, in which the displacement members are tracks (12), and the mobile accessory is a leveling and stabilizing blade (14). [Claim 12] Architecture according to any one of claims 1 to 10, in which the mobile accessory (14) comprises at least one of the displacement members (12), the at least one hydraulic cylinder (15) being capable of moving the at least one of the displacement members (12) to bring the displacement members (12) closer to or further away from each other.