Patent Description:
The invention is applicable on working machines within the fields of industrial construction machines or construction equipment, in particular excavators and articulated haulers. Although the invention will be mainly described with respect to an excavator, the invention is not restricted to this particular machine, but may also be used in other working machines such as articulated haulers, dump truck and backhoe loaders. , loaders, skid steer loaders, as far as it is equipped of linear cylinders to drive the movement of the equipment.

In recent years, there has been a clear trend towards the electrification of vehicles, and thus a move away from the use of fossil fuels that cause greenhouse gas emissions. Electric vehicles also have the advantage of being much quieter than their thermal counterparts.

This trend is now spreading to construction machinery which, until now, has included a combustion engine driving a hydraulic pump. Gradually, internal combustion engines will be replaced by electric motors. There are also solutions to replace the hydraulic system and the various cylinders that make it up. Today, the solution mainly consists of replacing the hydraulic cylinders with electric cylinders. In practice, however, this poses many problems, including bulk, exposure to shocks and above all potentially irreversible deformation or wear, or even breakage, caused by the induced forces.

It is well known that during certain operations, such as the digging or dumping phases, relatively large forces are applied in the axis of the linear actuators. Traditionally, i.e. with hydraulic cylinders, pressure limiters in the form of safety valves are used, which allow part of the oil contained inside the cylinder to be evacuated and thus limit the mechanical stresses induced on the cylinder body and the rod. However, and to the knowledge of the Applicant, nobody has so far succeeded in solving this problem with electric cylinders, with performances similar to that of hydraulic cylinders.

<CIT> proposes an original design of electric cylinder, in which the electric motor is housed inside the cylinder rod. This electric motor drives a threaded hub which engages inside a cylinder forming the cylinder body. Although this design of electric actuator is rather original, it is not certain that it solves the problems of deformation or breakage related to the induced forces and the above mentioned electric cylinder, which is fragile, remains exposed to potential external shocks.

On the other hand, <CIT> proposes an electric excavator, in which the hydraulic cylinders are replaced by electric actuators, which comprise an electric motor driving an actuating rod through a wheel and worm, the rod comprising a first end attached to the wheel and a second end attached to the mobile part of the excavator, such as a segment of the articulated arm.

In another register, <CIT> discloses a kind of excavator, in which the mast is mounted on a lifting platform. The lifting platform is moved vertically by means of a scissor mechanism, which is driven by an electric actuator. This actuator consists of an electric motor driving a threaded rod in rotation, which passes through a threaded hole delimited by a carriage. The rotation of the threaded rod around its axis causes the translational movement along the axis of the rod. One of the bars of the scissor mechanism is articulated on the carriage, so that the movement of the carriage causes the platform to move in a vertical direction.

<CIT> discloses an electric actuator for a construction equipment according to the preamble of claim <NUM>. This electric actuator works similarly to a hydraulic cylinder: It comprises an electric motor that moves a push rod back and forth using a screw/nut combination.

<CIT> discloses an electric actuator in which an electric motor is used to move an internal cylinder back and forth inside an external cylinder (telescopic system). A transmission device enables to transform the motor torque into a linear force.

Finally, <CIT> discloses a geotechnical system for excavating the location of foundation pillars.

An object of the invention is to provide a simple, effective, robust and economical solution to replace hydraulic cylinders of a construction equipment with electric actuators. In detail, the integration of the actuator(s) inside the equipment offers large possibilities to fit the components of the actuator(s) and adopt an appropriate sizing. This solution will make it possible to propose fully electrically driven construction equipment on the market.

The object is achieved by a construction equipment according to claim <NUM>, comprising at least one electric actuator including:.

According to the invention, at least the electric motor, the rod and the sliding member are integrated into said second element of the construction equipment.

Advantageously, guiding means are fixed relative to second element or integral with said second element.

The electric actuator(s) with which the construction equipment according to the invention is equipped are build up from simple elements "off the shelf" whose performance, durability and efficiency have been proven in the past. Moreover, the guiding means and the integration of sensitive elements of the actuators into the construction equipment enables to achieve very promising results in terms of robustness, durability and efficiency.

Moreover, and thanks to the usage of an electric motor, energy recovery can be applied through the electric motor acting as generator, during driven movements, typically when excavator boom is moving down under gravity.

Advantageously, the construction equipment of the invention includes the following (optional) features:.

<FIG> shows a construction equipment <NUM> (also referred to as a "construction machine" or "work machine"), which in the example is an excavator. Obviously, and as mentioned above, the invention is not limited to this particular example as it can be applied to any other construction machine.

The construction machine <NUM> comprises an upper frame (also known as "platform") <NUM> that can be pivoted around a vertical axis. The upper frame4 includes the driver cab. It is rotationally mounted on a lower frame equipped with a pair of continuous tracks <NUM>, e.g. caterpillars tracks <NUM>.

The excavator <NUM> further includes an excavator arm <NUM>, which comprises a boom <NUM> that is rotatable relative to the upper frame <NUM> and a dipper <NUM> (also known as "stick" or "arm") that is rotatable relative to the boom <NUM>. Besides, a tool <NUM>, such as a bucket, is removably attached to the end of the dipper <NUM>.

In reference to <FIG>, <FIG>, Numeral reference <NUM> denotes the articulation (or hinge) between boom <NUM> and upper frame <NUM>, Numeral reference <NUM> denotes the articulation (or hinge) between boom <NUM> and dipper <NUM> and Numeral reference <NUM> denotes the articulation between tool <NUM> and dipper <NUM> (Cf.

As a general rule, and in compliance with the applicable standards, the axes represented in dash dot on the figures are axes of rotational movement. No numeral reference has been added to avoid overloading the drawings.

In known manner, the articulations <NUM>, <NUM> and <NUM> allow rotating the boom <NUM>, dipper <NUM> or tool <NUM> around an axis of rotation parallel to the ground surface. Accordingly, when the construction equipment lays on a flat surface, said axis or rotation is horizontal. However, in variant, some construction equipment include articulation(s), linked to actuator(s), whose axis of rotation is not parallel to the ground.

In the example, the boom <NUM> is angle-shaped, which means that it includes two straight segments that delimit between them an angle of approximately <NUM>°.

The construction machine <NUM> is specific in that it is entirely electric. In other words, the construction machine <NUM> has neither a thermal engine, nor hydraulics. The continuous tracks <NUM> are driven by at least two electric motors (not shown), respectively one for each track <NUM>, and the movements of the excavator arm <NUM> and tool <NUM> are achieved thanks to electric actuators, respectively three electric actuators <NUM>, <NUM> and <NUM> from <FIG>, whose characteristics are detailed below.

Each actuator consists of a rod <NUM>, extending along a longitudinal axis X12 and a sliding element <NUM> (which can also be called "carriage"), movable along the rod <NUM>.

Each actuator also comprises an electric motor <NUM>, for converting electrical energy into movement of the sliding element <NUM> along the longitudinal axis X12. For instance, electrical energy can be supplied from a rechargeable on-board battery pack (not shown), e.g. a Lithium-ion battery pack.

The electric motor <NUM> is preferably a DC motor, e.g. a Brushless DC motor (BLDC). However, in variant, it could also be an AC motor.

Each actuator further includes a connecting rod <NUM>, comprising a first end 18A which is articulated to the sliding element <NUM> about a pivot axis perpendicular to the longitudinal axis X12 and a second end 18B which is articulated to a first element of the construction machine <NUM>.

In the embodiment of <FIG> and <FIG>, the excavator <NUM> includes a first actuator <NUM> for moving the boom <NUM>, whereby the second end 18B of the connecting rod is attached to a hinge A of the platform/upper frame <NUM>. The excavator <NUM> further includes a second actuator <NUM> for moving the dipper <NUM>, whereby the second end 18B of the connecting rod is attached to a hinge B of the dipper <NUM> and a third actuator <NUM> for moving the tool <NUM>, whereby the second end 18B of the connecting rod is attached to a hinge C of the tool <NUM>.

Accordingly, in the embodiment of <FIG> and <FIG>, said first element can be the upper frame <NUM>, the dipper <NUM> or the tool <NUM>.

In the example of <FIG>, the hinges B and C to which are attached the second ends 18B of connecting rods <NUM> are part of the element to be actuated, while hinge A belongs to another element, resp. the upper frame <NUM>.

Advantageously, at least the electric motor <NUM>, the rod <NUM> and the sliding member <NUM> are integrated, and then protected into a second element of the construction equipment, such as the boom <NUM> or dipper <NUM>. Accordingly, rod axis X12 is fixed/immobile relative to said second element. More precisely, the only degree of freedom of rod <NUM> relative to second element is the rotation about its own axis X12.

Preferably, said second element is part of the metallic structure of the construction equipment <NUM>. As its name indicates, the metallic structure, or carcass, is an assembly of pieces of metal making up the framework of the construction equipment <NUM>.

For instance, upper frame <NUM> and excavator arm <NUM> are part of the metallic structure of construction equipment <NUM>. Basically, the metallic structure can be formed by metallic sheets joined together.

Besides, and in order to avoid any confusion or misunderstanding, it is clear that the first and second elements of the construction equipment, to which it is referred to above, are two distinctive elements, which means that it is not one and the same element.

In the embodiment of <FIG> and <FIG>, elements <NUM>, <NUM> and <NUM> of actuators <NUM> and <NUM> are integrated into the boom <NUM> as second element and elements <NUM>, <NUM> and <NUM> of actuator <NUM> are integrated into the dipper <NUM> as second element.

By the expression "integrated into", it is meant that elements <NUM>, <NUM> and <NUM> of each actuator are housed or encased inside a sort of protective shield, which is actually part of the machine framework.

Advantageously, said second element <NUM> or <NUM> delimits an opening <NUM>, in the form of a slot, which extends in a direction parallel to that of the rod <NUM>, to allow the passage of the connecting rod <NUM>. This opening <NUM> is particularly visible in <FIG>.

In the example of an excavator, the boom <NUM> and dipper <NUM> are traditionally made from steel plates, potentially associated to casted parts, which delimit an unused hollow volume. The idea here is therefore to use this unused hollow volume to house at least the electric motor <NUM>, the carriage <NUM> and the rod <NUM>, in order to protect these elements from shocks. It is therefore understandable that, structurally, the carcass of the excavator <NUM> according to the invention which could be described as "<NUM>% electric" is similar to that of a traditional hydraulic excavator, except that openings, e.g. opening <NUM>, are created to allow passage of connecting rod <NUM>.

Each actuator also includes guide means to guide the movement of the sliding element <NUM> along the longitudinal axis X12. These guide means can take several forms, including the one shown in <FIG>, where the guidance is actually provided by the second element <NUM> or <NUM> to which it is referred to above. Specifically, sliding element <NUM> has a cross-section approximately the same as that of said second element <NUM> or <NUM>, so that rudimentary guidance is achieved.

In the example shown in <FIG>, sliding element <NUM> and rod <NUM> form a helical link (Cf. https://www. php/Liaison h%C3%A9lico%C3%AFdale). The helical link, or connection, is achieved by contact between two helical surfaces.

For instance, this helical link is achieved by using a ball screw or roller screw mechanism (not shown). The principle of this mechanism is to use rolling elements, such as balls or rollers, to limit friction between the rod <NUM> and the sliding element <NUM>. As this type of helical connection is well known from the state of the art, no further details are given here. There is a lot of information on the internet on this subject, for example on the following internet pages, the content of which is incorporated herein by reference:.

In reference to <FIG>, when electric motor <NUM> is switched on (i.e. supplied with electric power), it drives rod <NUM> in rotation around axis X12, as depicted by arrow R1. Thanks to the helical link, the rotation of rod <NUM> leads to a translation of the carriage <NUM> forward or backward along rod <NUM> (Cf. Arrow D1), depending on the rotation direction of the E-motor <NUM>. As a result, connecting rod <NUM> pivots around hinge A and forces the boom <NUM> to rotate around the articulation <NUM> between boom <NUM> and upper frame <NUM> (Cf. Accordingly, the electric actuator <NUM> forms a simple means to move the boom <NUM> up or down, depending on the sense of rotation of the E-motor <NUM>.

Typically, the axis of articulation between sliding element <NUM> and connecting rod <NUM> is parallel to the axis of articulation between connecting rod <NUM> and said first element (e.g. upper frame <NUM>, dipper <NUM> or tool <NUM>) of the construction equipment to which it is referred to above. Also, it can be noted that the axes of articulations provided at the ends 18A and 18B of connecting rod <NUM> are parallel to the axes of articulations <NUM>, <NUM> and <NUM> of the excavator <NUM>.

According to a variant not shown, sliding element/carriage <NUM> is fixed/fastened to an external body (also known as the "nut" or "nut element") of the ball screw or roller screw mechanism to which it is referred to above, in order to limit the efforts that are transmitted to the ball/roller screw mechanism. This means that the sliding element is not part of the ball/roller screw mechanism as such. Typically, sliding element <NUM> can be fastened to nut element of the ball/roller screw mechanism using conventional fasteners, such as rivets, screws or bolts.

<FIG> show a second embodiment of the invention. For the purpose of conciseness, only the differences relative to the first embodiment are mentioned below.

In this second embodiment, the main difference with respect to the first embodiment is that electric motor <NUM> constitutes the carriage/sliding element, i.e. electric motor <NUM> slides along rod <NUM>. Specifically, the electric motor <NUM> comprises a hollow rotor, which is engaged with rod <NUM> by means of a frictionless transmission system such as a ball screw or roller screw system. Thus, the rotor of motor <NUM> has a "nut" function, inverted commas indicating that it is not a nut in the conventional sense. In this embodiment, and contrary to the first embodiment, rod <NUM> is fixed in rotation around its longitudinal axis X12.

Also, in this second embodiment, the translational guidance is provided by at least one rail, preferably two rails <NUM>, which extend parallel to rod <NUM> and are each engaged in a bore of the electric motor as a sliding element. Precisely, the rails are engaged each through a respective hole extending through two brackets supporting motor <NUM>.

In the example, each rail is a cylinder with a circular cross-section, but it is obvious that, alternatively, the cross-section of the cylinder could be different, e.g. rectangular.

In reference to <FIG>, when electric motor <NUM> is switched on (i.e. supplied with electric power), the rotor <NUM> of the electric motor is driven in rotation around axis X12. Thanks to the helical link, and since rod <NUM> is fixed in rotation in this embodiment, rotation of the rotor <NUM> is achieved simultaneously with a translation along rod <NUM>. The rotor <NUM> drives the stator <NUM> in translation along the rod. In other words, the motor <NUM> moves forward or backward along rod <NUM> (Cf. Arrow D1) as the rotor <NUM> rotates around axis X12, depending on the rotation direction of the E-motor <NUM>. As a result, connecting rod <NUM> pivots around hinge A and forces the boom <NUM> to rotate around the articulation <NUM> between boom <NUM> and upper frame <NUM> (Cf. Accordingly, the electric actuator <NUM> forms a simple means to move the boom <NUM> up or down, depending on the sense of rotation of the E-motor <NUM>.

<FIG> show a third embodiment of the invention. For the purpose of conciseness, only the differences with respect to the first two embodiments are mentioned below.

In this third embodiment, the sliding element <NUM> and the rod <NUM> are connected to each other in the manner of a sliding connection. In this example, the electric motor <NUM> is a linear motor with a rotor <NUM> forming the sliding element and a stator <NUM> forming the rod.

Linear motors in general are, for example, described on the following web page https://en. org/wiki/Linear motor , the content of which is incorporated herein by reference.

Also, in this third embodiment, the rod <NUM> takes the form of a rail, with a cross-section comparable to that of a I-beam, but asymmetrical. Carriage <NUM> has a complementary cross-section, so that carriage <NUM> is naturally guided in translation along rod <NUM>. Therefore, rail <NUM> extends inside a groove of sliding element <NUM>, said groove being of complementary shape.

In reference to <FIG>, when electric motor <NUM> is switched on (i.e. supplied with electric power), the carriage (e.g. the rotor) is driven in translation along rod <NUM> operating as the stator. In other words, carriage moves forward or backward along rod <NUM> (Cf. Arrow D1), depending on the control signal transmitted to the E-motor <NUM>. As a result, connecting rod <NUM> pivots around hinge A and forces the boom <NUM> to rotate around the articulation <NUM> between boom <NUM> and upper frame <NUM> (Cf. Accordingly, the electric actuator <NUM> forms a simple means to move the boom <NUM> up or down.

<FIG> shows a variant of the invention, in which actuator <NUM> is used to move an accessory (or attachment) on the construction machine, in this case a thumb <NUM>. In general, a thumb makes it easier to pick, hold and move awkward material such as rocks, concrete, branches, and debris that does not fit into the bucket <NUM>.

In this embodiment, and contrary to the previous ones, the protection casing is a box <NUM> fastened to the machine <NUM>, which means that the protection casing <NUM> is something that can be fitted a posteriori. In the example, the protection casing <NUM> is attached below the dipper <NUM>. Accordingly, the electric motor <NUM>, the rod <NUM> and the sliding element <NUM> are housed inside this removable box <NUM>, which fulfills as well a guiding function for the carriage <NUM>.

Typically, this protection casing <NUM> can be easily disassembled from the machine <NUM>. For example, this box could be bolted below the boom <NUM> or dipper <NUM>. An advantage of this configuration is that it facilitates maintenance operations on the electric motor <NUM>. It also allows conserving the exact same framework relative to a hydraulic construction machine.

Accordingly, the expression "protection casing" has to be interpreted in the broadest possible manner: For instance, a protection casing does not necessarily delimit an enclosed volume: It could be a rectangular box with three sides.

<FIG> shows another variant of the invention, applied to a hauler (or articulated hauler). For the clarity of the drawings, only the rear portion of the hauler is represented herein. In this variant, the electric actuator <NUM> is used to operate a skip <NUM> of the hauler, i.e. for tipping the skip up and down.

In this example, when electric motor <NUM> is switched on (i.e. supplied with electric power), it drives rod <NUM> in rotation around axis X12. Thanks to the helical link, the rotation of rod <NUM> leads to a translation of the carriage <NUM> forward or backward along rod <NUM>, depending on the rotation direction of the E-motor <NUM>. As a result, connecting rod <NUM> forces the skip <NUM> to rotate around the articulation between the skip and chassis (Cf. Accordingly, the electric actuator <NUM> forms a simple means to tip the skip <NUM> up and down, depending on the sense of rotation of the E-motor <NUM>.

<FIG> shows another variant of the invention, in which guiding means comprise two guiding rails <NUM> extending parallel one to each other along a direction parallel to axis X12. These two rails <NUM> are fixed relative to second element in the example formed by excavator boom. More particularly, these two rails can be integral with second element, i.e. with boom metallic structure. In the example, the rails <NUM> provide longitudinal guidance for one carriage/sliding element <NUM> moving along rod <NUM>. In a variant not shown, the rails can provide guidance for two or more carriages.

Also, in a variant not shown, guiding means could include more than two rails, e.g. three or four distinctive rails.

<FIG> shows another embodiment of the invention, in which the electric motor and sliding element (carriage) are one and the same element. In detail, the output shaft 16A of the electric motor meshes with a gear wheel 17A (according to a worm drive engagement) which itself meshes with a rack <NUM> (according to rack and pinion engagement) which can also be considered as a rod similar to that of other embodiments of the invention described above. Therefore, rotation of the motor output shaft is transmitted to gear wheel, which induces a translation of the motor/carriage back and forth along the rack (As represented by double sided arrow D1 on <FIG>), depending on rotation direction of the motor output shaft. The sliding element, comprising the E-motor <NUM> and a support element <NUM>, is articulated with a first end of connecting rod <NUM>. The other end of connecting rod <NUM> is articulated on first element of the construction equipment, which is in this specific example upper frame <NUM>.

The guiding of the sliding element <NUM>+<NUM> can be insured by the rack <NUM>, or by a dedicated guiding arrangement (not shown).

In a variant not shown, the system could include more than one rack, e.g. two racks which engage each with one or more gear wheels of the carriage.

<FIG> represents an alternative embodiment, in which the output shaft 16A of the electric motor <NUM> meshes with at least two successive gear wheels 17A, for example three successive gear wheels 17A, which all engage each with one and the same rack 17B thanks to pinion and rack engagement. Gear wheels 17A are mounted/provided on a support <NUM> acting as sliding element. Rotation of the motor output shaft induces a rotation of the gear wheels and accordingly a movement along rack 17B. Support <NUM> is articulated with one end of a connecting rod <NUM>, the function of which is identical to that of the other embodiments described above.

Last, <FIG> shows another embodiment of the invention, in which the electric motor <NUM> is a linear actuator configured to move a rod <NUM> back and forth. A sliding element or carriage <NUM> is fixed to the rod <NUM>, in particular at one end opposite to motor <NUM>. As for other embodiments, connecting rod <NUM> is articulated to carriage <NUM>. Again, rod axis X12 is fixed/immobile relative to second element, which is in the example boom <NUM>.

In a variant not shown, applicable to any one of the described embodiments herein, the assembly of E-motor <NUM> and rod <NUM> can move/rotate inside second element, e.g. boom <NUM>, of the construction equipment. These movements are achieved by introducing some functional clearances/pivot points and allow absorbing some deformation.

It is to be understood that the present invention is not limited to the embodiments described above and illustrated in the drawings; rather, the skilled person will recognize that many changes, variants and modifications may be made within the scope of the appended claims.

For example, at least one of the actuators described above may include an additional electric motor. Typically, the two electric motors could each be located at one end of the rod <NUM>. Alternatively, the two electric motors could be arranged side by side (i.e. in parallel). These two electric motors may or may not be identical.

Obviously, and in the same spirit, the actuator(s) can include two or more rods <NUM>, regardless of the number of motors <NUM>. For instance, only one motor can be used to drive two rods <NUM>, using an appropriate transmission.

Similarly, the actuator(s) can include two or more sliding elements <NUM>, regardless of the number of rods <NUM>.

Similarly, the actuator(s) can include two or more connecting rods <NUM>, regardless of the number of sliding elements <NUM>.

Also, in another example, two or more actuators can be used to actuate the same element.

In another example, one could very well imagine a configuration where the rod would not be driven directly by the electric motor. In this example, the electric motor could be arranged perpendicular to the axis of the rod and drive the rod by means of an angle gear mechanism, such as a worm and wheel. The choice of configuration depends on the space available for the motor(s). In another example, the E-motor <NUM> could be arranged parallel to rod <NUM>, (but not coaxial: side by side). Accordingly, a transmission system is provided between motor <NUM> and rod <NUM>. This transmission system could be a gear set (chain of pinions), a belt or a chain. It also acts as a speed reducer.

In another example, the electric motor could include a speed reducer, typically an epicyclic reducer (planetary gear set).

In another example, at least one of the electric actuators <NUM> fitted to Construction Machinery <NUM>, preferably each actuator <NUM>, includes a static brake (also known as a "safety brake") to hold the sliding element <NUM> in place when the electric motor <NUM> is switched off. Further details of this type of brake can be referred to what already exists on this subject and is described on the following web page:
https://fr. org/wiki/Frein de s%C3%A9curit%C3%A9.

In another example, the pivot connections between the elements of actuator <NUM> may include a cushioning device, such as a bush, to protect the mechanism from shocks or induced forces.

In another example, at least one of the electric actuators <NUM> fitted to the construction machinery, preferably each actuator <NUM>, includes a position or rotation sensor to provide closed loop or closed loop control of the position of the moving parts of the machine <NUM>.

In another example, construction machine <NUM> could be equipped with one or more force or torque sensors.

In another example, the or each opening <NUM> is provided with dust and/or water protection device, such as brush, rubber bands and/or deflector(s).

In another example, the guiding means described above could be supplemented or replaced by wheels, to make the carriage <NUM> roll along a surface so as to ensure frictionless guidance.

Claim 1:
A construction equipment (<NUM>), comprising at least one electric actuator (<NUM>, <NUM>, <NUM>; <NUM>) including:
- a rod (<NUM>), extending along a longitudinal axis (X12);
- a sliding member (<NUM>), movable along the rod (<NUM>);
- an electric motor (<NUM>), for converting electrical power into a movement of the sliding member (<NUM>) along the longitudinal axis (X12);
- guiding means (<NUM>; <NUM>; <NUM>; <NUM>; <NUM>) for guiding the movement of the sliding member (<NUM>) along the longitudinal axis (X12);
characterized in that:
- said electric actuator further includes a connecting rod (<NUM>), comprising a first end (18A) which is articulated on sliding member (<NUM>) and a second end (18B) which is articulated on a first element (<NUM>; <NUM>; <NUM>; <NUM>; <NUM>) of the construction equipment, in order to move the first element relative to a second element (<NUM>; <NUM>; <NUM>) or inversely; and in that
- at least the electric motor (<NUM>), the rod (<NUM>) and the sliding member (<NUM>) are integrated into said second element (<NUM>; <NUM>; <NUM>) of the construction equipment.