Aerial work platform with combustion engine or electric motor drive

Description

[0001] The present invention relates to a lifting platform.

[0002] The invention relates more specifically to nacelles whose translation on the ground, typically by means of wheels, is motorized and whose components of the lifting structure are movable by hydraulic actuators which are actuated by a fluid, typically oil, which circulates in an open circuit under the effect of a pump, generally with variable displacement. For example, US 2021 / 261102 discloses an elevating nacelle whose hydraulic system comprises a pump driven by a motor and sucking a fluid from a reservoir to send it to a distribution unit where first valves control the actuation of hydraulic actuators moving a rotating turret and a deployable arm of the nacelle, while second valves of the distribution unit control the actuation of hydraulic actuators acting on the brake release of the wheels of the nacelle.In US 2021 / 261102, these first and second valves are all connected to the pump in the same way.

[0003] This type of nacelle often includes a thermal engine whose drive output is used to drive both the variable displacement pump and a hydraulic pump of a hydrostatic transmission whose hydraulic motor drives the ground-mounted wheels. Alternatively, the nacelle includes an electric motor that drives the variable displacement pump and the ground-mounted wheels.

[0004] When the platform is thermally powered and uses the aforementioned hydrostatic transmission, it is necessary to equip the platform with a booster pump, driven by the thermal engine. This booster pump allows fluid to be introduced under a predetermined fixed pressure into the closed circuit of the hydrostatic transmission in order to compensate for leaks and renew the oil, in particular to cool and filter it. The discharge from the booster pump is often also used to actuate hydraulic actuators involved in accessory functions, in particular in connection with ground translation, such as wheel brake release. This thermally powered hydraulic architecture is satisfactory, but the booster pump induces constant energy consumption, even when the platform is controlled to move its lifting structure without being controlled in ground translation.

[0005] When the platform is electrically powered, the use of a booster pump is no longer necessary to ensure ground movement as such. However, in this case, the hydraulic architecture becomes more complex if the aforementioned accessory functions are to be operated using hydraulic actuators.

[0006] More generally, we note that hydraulic architectures respectively associated with a thermal engine and an electric engine have their own advantages and disadvantages, which tend to distance the respective specificities of these two architectures. The design, industrialization and manufacturing of these two hydraulic architectures therefore induce substantial constraints and costs, which cannot be shared.

[0007] The aim of the present invention is to propose a new lifting platform which, while being available in a thermally powered version and an electrically powered version, is simpler to design, industrialize and manufacture, while optimizing its energy consumption.

[0008] To this end, the invention relates to a lifting platform, as defined in claim 1.

[0009] One of the ideas behind the invention is not to use a booster pump as mentioned above, but to integrate into the hydraulic system of the lifting platform a booster block, which is not motorized and which cooperates with a pressure-regulated pump block.According to the invention, this booster block controls the pressure regulation of the pump block so that (i) the pump block delivers the fluid with a delivery pressure which, regardless of the hydraulic actuators controlled in actuation, in particular for the needs of translation on the ground and / or for the movement of the lifting structure, is always sufficient to allow the actuation of these hydraulic actuators to be actuated and (ii) the hydraulic actuator(s) including the one involved in brake release, which need to be supplied with fluid under a predetermined booster pressure to be actuated, are efficiently supplied by the booster block as soon as this or these hydraulic actuators are controlled in actuation.As a result, the drive of the pump unit of the nacelle according to the invention can be either thermal or electrical: in other words, the same hydraulic components can be installed in the same locations within a nacelle with thermal motorization and within a nacelle with electrical motorization, as illustrated in more detail below. The design, industrialization and manufacture of a thermal version and an electric version of the nacelle according to the invention are thus remarkably improved.In addition, the boosting operated by the boost block of the nacelle according to the invention is energetically optimized in the sense that the pump block adapts its hydraulic power to the actual needs: when the nacelle is not controlled for the purposes of its translation on the ground, all the hydraulic power of the pump block can be used to actuate the hydraulic actuators acting on the lifting structure, in particular without it being necessary to run “for nothing” a boost pump as mentioned above; conversely, when the nacelle is controlled solely for the purposes of its translation on the ground, the hydraulic power of the pump block is limited to the supply of the accessory supply line by the boost block with fluid under the boost pressure. In practice, various embodiments can be envisaged for the pump block and for the boost block, as detailed below.Furthermore, the invention finds a remarkable application to bridge nacelles, also as presented in more detail below.

[0010] Additional advantageous characteristics of the lifting platform according to the invention are specified in the other claims.

[0011] The invention will be better understood by reading the following description, given solely by way of example and with reference to the drawings in which: there figure 1 is an elevation view of a lifting platform according to the invention; figure 2 is a diagram of some components of the nacelle of the figure 1 , in particular a hydraulic system of the latter; and the figure 3 is a view similar to the figure 2 , illustrating an alternative embodiment for the lifting platform, in accordance with the invention.

[0012] On the figures 1 And 2a lifting platform 1 is shown allowing an operator to reach an area located at height in order to carry out work there.

[0013] As shown in the figure 1 , the lifting platform 1 comprises a chassis 10 resting on the ground.

[0014] The chassis 10 is provided with wheels 11A and 11B for its translation. In the preferred embodiment which is illustrated in the figures, these wheels are divided into a pair of front wheels 11A and a pair of rear wheels 11B. In a variant not shown, all or part of the front wheels 11A and the rear wheels 11B can be replaced by tracks for the purposes of translating the chassis 10 on the ground. More generally, the front wheels 11A and the rear wheels 11B are only examples of ground translation members which equip the chassis 10.

[0015] The front wheels 11A are steered, being steerable to the left and to the right relative to an anteroposterior geometric axis of the chassis 10, extending parallel to the ground. This inclination of the wheels 11A makes it possible to rotate the chassis 10 in a corresponding manner relative to the ground. The wheels 11A can thus be oriented in an adjustable manner relative to the chassis 10 to modify the direction in which the chassis 10 translates on the ground and thus direct the lifting platform 1 on the ground following a trajectory controlled by the operator using this platform. For this purpose, as shown schematically in the figure 2 , the lifting platform 1 comprises a hydraulic actuator 20 which acts on the front wheels 11A so as to adjust their orientation relative to the chassis 10. In practice, this hydraulic actuator 20 is supported by the chassis 10. By way of example, the hydraulic actuator 20 is a double-acting, double-rod cylinder, it being emphasized that this example is not limiting and that other embodiments for the hydraulic actuator 20, as such, are known in the art, in particular in the field of lifting platforms. In a variant not shown, the rear wheels 11B are steered, replacing or in addition to the front wheels 11A: in this case, the lifting platform 1 comprises a hydraulic actuator, which is similar to the hydraulic actuator 20 but which acts on the rear wheels 11B so as to adjust their orientation relative to the chassis 10.

[0016] According to a preferred embodiment, which is implemented here and which is schematically illustrated in the figure 2 , the front wheels 11A are respectively carried by the opposite ends of the same front axle 12A and form with the latter a front axle 13A of the chassis 10. Similarly, the rear wheels 11B are respectively carried by the opposite ends of the same rear axle 12B and form with the latter a rear axle 13B of the chassis 10. The chassis 10 is thus a two-axle chassis, it being understood that in a variant not shown, the number of axles of the chassis 10 may be equal to or greater than three.

[0017] The lifting platform 1 is self-propelled so that it can move by itself on the ground. For this purpose, the lifting platform comprises a motorization 30 which makes it possible to drive at least some of the wheels 11A and 11B, here all the wheels 11A and 11B, so as to move the chassis 10 relative to the ground. In the embodiment of the figure 2 , the motorization 30 is thermal in the sense that it comprises a thermal engine 31 whose output provides the motive power necessary for the operation of the lifting platform 1. In practice, this thermal engine 31 is supported by the chassis 10. To ensure the transmission between the thermal engine 31 and the wheels 11A and 11B, the lifting platform 1 comprises a hydrostatic transmission 32 belonging to a hydraulic system S of the lifting platform, as indicated schematically in the figure 2 . The hydraulic system S uses a fluid, such as oil. This hydrostatic transmission 32 includes a hydraulic pump 33 to which the drive output of the thermal engine 31 is mechanically connected, a hydraulic motor 34 whose drive output is mechanically connected to the wheels 11A and 11B, and a closed circuit 35 in which the fluid circulates, in a closed loop, between the hydraulic motor 34 and the hydraulic pump 33. In practice, the specificities of the thermal engine 31 and the hydrostatic transmission 32 are not limiting, it being noted that such a hydrostatic transmission and such a thermal engine are known as such in the art, in particular in the field of aerial work platforms. Preferably, the hydraulic pump 33 has a variable displacement which is controlled by a control member 36, such as a cylinder.In addition, the closed circuit 35 is advantageously equipped with a scavenging valve 37 which regularly removes fluid from the closed circuit 35 to filter and / or cool it.

[0018] To ensure the transmission between the hydraulic motor 34 and the wheels 11A and 11B, the front 12A and rear 12B axles each include a transmission shaft 14A, 14B, the opposite ends of which are kinematically connected to the front 11A and rear 11B wheels respectively, and which advantageously includes a differential 15A, 15B. In addition, the drive output of the hydraulic motor 34 is connected, via a gearbox 16, to a central transmission shaft 17 the opposite ends of which are respectively connected to the transmission shafts 14A and 14B, in particular to their respective differentials 15A and 15B. In practice, the specific features of the mechanical transmission which has just been described between the hydraulic motor 34 and the wheels 11A and 11B are not limiting.

[0019] In all cases, the lifting platform 1 comprises a braking device 40 which, in the deactivated state, brakes at least some of the wheels 11A and 11B. Thus, in the absence of activation of the braking device 40, the latter mechanically blocks the rotation of at least some of the wheels 11A and 11B and thus prevents the movement of the chassis 10 relative to the ground. In a manner known per se and not detailed here, the braking device 40 comprises for example one or more springs which, when the braking device 40 is deactivated, apply brakes against the wheels and / or against an element of the mechanical transmission, kinematically linked to the wheels.In order to activate the brake release device 40 and thus allow the wheels 11A and 11B to be driven freely by the motor 30, the lifting platform 1 comprises a hydraulic actuator 50 acting on the brake release device 40: when this hydraulic actuator 50 is actuated, it activates the brake release device 40, for example by neutralizing or overcoming the force of the aforementioned spring(s) so as to separate the brakes normally applied by these springs. On the . figure 2 , the brake release device 40 is schematically illustrated as comprising two elements 40.1 and 40.2, which act mechanically on the transmission shaft 14B of the rear axle 12B, on either side of the differential 15B, and which can be activated by two respective elements 50.1 and 50.2 of the hydraulic actuator 50. In practice, the brake release device 40 and the hydraulic actuator 50 are supported by the chassis 10. Of course, in a variant not shown, the non-limiting arrangements which have just been described with reference to the figure 2 for the brake release device 40 and the hydraulic actuator 50 at the transmission shaft 14B can be provided, as a replacement or in addition, at the transmission shaft 14A.

[0020] According to an advantageous optional arrangement, which is implemented in the embodiment illustrated in the figures, the differential 15B of the transmission shaft 14B of the rear axle 12B can be locked by a locking device 60, which is known per se and which is only shown schematically in the figure 2 . The locking device 60 allows, when activated, to lock the differential 15B so that the two rear wheels 11B are forced to turn at the same speed even if one of them slips or is in the void, in particular due to an uneven state of the ground. In order to activate the locking device 60 and thus lock the differential 15B, the lifting platform comprises a hydraulic actuator 70 acting on this locking device 60: when the actuator 70 is actuated, it activates the locking device 60, for example by forcing a direct bridging on either side of the differential 15B. In practice, the locking device 60 and the hydraulic actuator 70 are supported by the chassis 10.Of course, in a variant not shown, as a replacement or in addition to the locking device 60 and the associated hydraulic actuator 70, a locking device and a hydraulic actuator, respectively similar to the latter, can be provided for the differential 15A.

[0021] According to another advantageous optional arrangement, which is also implemented in the embodiment illustrated in the figures, the front axle 13A is oscillating, that is to say that it is mounted on a fixed part of the chassis 10 in a movable manner in rotation about an anteroposterior geometric axis of the chassis, extending parallel to the ground and passing through the middle of the front axle 12A. Such an oscillating mounting for the axle 13A is known as such in the art, in particular in the field of lifting platforms, and the specific features of this oscillating mounting are not limiting. Moreover, the reader can refer to document EP 3 792 213 for a detailed example of such specific features.Whatever these specificities, the lifting platform 1 comprises one or more hydraulic actuators which act on the front axle 13A to control the oscillation of the latter and which, here, are two cylinders 80 and 81, as illustrated schematically in the . figure 2 . The cylinders 80 and 81 are supported by the chassis 10 and are fed with fluid in order to be kept in contact with the front axle 12A. When the cylinders 80 and 81 are actuated, these cylinders, the fluid supply of which is maintained by feeding in particular to compensate for leaks, are freely deployable by means of the circulation of fluid between them, so as to allow the front axle 13A to oscillate freely, which is typically to be implemented when the lifting platform 1 moves on the ground to allow the axle 13A to follow potential irregularities in the ground. When the cylinders 80 and 81 are not actuated, they are blocked, being prevented from modifying their deployment, and thus lock the front axle 13A in oscillation, which is typically to be implemented when the lifting platform 1 is stationary on the ground and deployed at height.Here again, a more detailed example of the operation of the cylinders 80 and 81 is given in EP 3 792 213 to which the reader can refer. Of course, in a variant not shown, the rear axle 13B can be provided as oscillating, replacing or supplementing the oscillation for the front axle 13A, by means of arrangements similar to what has just been described for the front axle 13A.

[0022] As shown in the figure 1 , the lifting platform 1 further comprises a platform 100 which is designed so that the operator using the lifting platform can stand thereon. The platform 100 is thus designed to accommodate this operator on board, as well as, where appropriate, one or more other persons and / or equipment in order to carry out work at height. For this purpose, the platform 100 comprises a floor 101, on which the operator stands, and a guardrail 102 which rises from the floor 101 surrounding the platform 100. In addition, the platform 100 is provided with a control panel 103 allowing the operator on board the platform to control the movement of the chassis 10 on the ground and the operation of a lifting structure 110 of the lifting platform 1, supporting the platform 100.

[0023] The lifting structure 110 is arranged on the chassis 10 so as to be able to move the platform 100 at least in height relative to the chassis. For this purpose, the lifting structure 110 comprises a turret 111, which rests on the chassis 10 and which is rotatable relative to the latter about an axis of rotation extending perpendicular to the ground, and an arm 112 which connects the turret 111 to the platform 100 and which is deployable so as to more or less separate the platform 100 from the turret 111, in particular upwards and laterally to the turret. In practice, the embodiment of the turret 111 is not limiting. Likewise, the embodiment of the arm 112 is not limiting: moreover, the term “arm” used here is understood in a broad sense and thus corresponds to an elongated mechanical structure, including several arm elements movable relative to each other for the purposes of deploying this mechanical structure.In the example shown in . figure 1 , the arm 112 is an articulated arm, the construction details of which are provided in FR 3 067 341 to which the reader can refer. In a variant not shown, the arm 112 is at least partially telescopic, including arm elements which fit into each other.

[0024] More generally, the embodiment of the lifting structure 110 is not limiting of the invention since, by moving parts of this lifting structure relative to each other and / or relative to the chassis 10, the positioning of the platform 100 relative to the chassis 10 is modified in a corresponding manner, the platform thus being controllable in movement, by means of the lifting structure 110, by the operator using the lifting cradle 1, in particular from the platform 100 using the control console 103.

[0025] Whatever the embodiment for the lifting structure 110, the movable parts of the latter can be driven in displacement relative to each other and / or relative to the chassis 10 by hydraulic actuators 120, which are integrated into the lifting platform 1 and only one of which is shown schematically in the figure 2 . Thus, in the embodiment considered here, the hydraulic actuators 120 act on the turret 111 for the purpose of rotating it, as well as on the arm 112 for the purpose of deploying it. As such, the hydraulic actuators 120 are known in the field of lifting platforms and the embodiment of each of them is not limiting, being obviously adapted to the range of the lifting structure 110 on which the hydraulic actuator 120 acts. For example, each of the hydraulic actuators 120 is a single-acting cylinder, a double-acting cylinder, a rotary actuator, etc.

[0026] The hydraulic system S of the lifting platform 1 makes it possible, by means of arrangements which will be presented below, to actuate the hydraulic actuators 20, 50, 70, 80 and 81 and 120 which have been described so far, by supplying them with fluid. For this purpose, as shown in the figure 2 , the hydraulic system S comprises a reservoir 130, containing a sufficient quantity of fluid for the operation of the hydraulic system S, and a circulation circuit 140 through which the fluid circulates between the reservoir 130 and the hydraulic actuators 20, 50, 70, 80, 81 and 120. In addition, the lifting platform 1 comprises a control unit 150 for controlling the hydraulic system S for the purpose of actuating the hydraulic actuators 20, 50, 70, 80 and 81 and 120. In practice, the control unit 150 comprises a computer or similar electronic components and is adapted to transmit control signals to the hydraulic system S, in particular electrical signals. The control console 103 is connected to the control unit 150 by any suitable means so that the control unit 150 is slaved to the control console 103, allowing the operator on board the platform to control the hydraulic system S.

[0027] The circulation circuit 140 comprises a pump unit 170 which allows the fluid to be circulated under pressure in the circulation circuit 140. The pump unit 170 can be driven by the heat engine 31, by being mechanically connected to the drive output of the latter. The pump unit 170 is connected to the reservoir 130 by a suction line 171 so as to be able to suck the fluid from the reservoir 130. The pump unit 170 is connected to a delivery line 172 in which the pump unit, when driven, delivers the fluid under a delivery pressure. This delivery pressure is variable, according to a pressure regulation. For this purpose, according to a preferred embodiment, both practical and economical, which is implemented at figure 2 , the pump unit 170 comprises a variable displacement pump 173, as well as a regulator 174. The pump 173 draws the fluid from the reservoir 130, via the suction line 171, and delivers the fluid under the discharge pressure into the discharge line 172. The regulator 174, which implements the pressure regulation of the pump unit 170, acts on a control member 175, here a cylinder, which controls the displacement of the pump 173. The regulator 174 thus makes it possible to adjust the displacement of the pump 173 in order to obtain a constant pressure differential between the pressure in the discharge line 172 and the pressure of an inlet 176 of the regulator 174. This amounts to saying that, in service, the regulator 174 maintains the discharge pressure in excess of the pressure at its inlet 176, with an overpressure value which is constant and which corresponds to the aforementioned pressure differential.As a non-limiting example, this pressure differential is approximately 20 bars. In practice, multiple embodiments, known as such in the art, are conceivable for the regulator 174 for the purposes of carrying out the pressure regulation of the pump unit 170 and are therefore not limiting: as an example, in the embodiment illustrated in . figure 2 , the regulator 174 comprises a first regulating member which makes it possible to maintain the pressure of the discharge line 172 at a value corresponding to the pressure of the inlet 176 increased by the aforementioned pressure differential by acting on the displacement of the pump 173 via the control member 175. A second regulating member makes it possible to cancel the displacement of the pump 173 when the pressure in the discharge line 172 reaches the preset maximum pressure value.

[0028] The circulation circuit 140 also includes a booster block 180 which, as explained below, performs two main functions, namely providing fluid booster and controlling the pressure regulation of the pump block 170.

[0029] At the inlet, the feeding block 180 is connected to the discharge line 172 by a branch supply line 181, so as to be supplied with fluid under the discharge pressure from the discharge of the pump block 170.

[0030] At the outlet, the feed block 180 is connected to a feed line 182 into which the feed block 180 sends the fluid from the bypass supply line 181 by regulating the pressure to a feed pressure. This feed pressure has a pre-set value, which, in an example considered here, is approximately 27 bars. For this purpose, the feed block 180 comprises a pressure reducer 183 which connects the bypass supply line 181 to the feed line 182. The pressure reducer 183 also connects the feed line 182 to a drainage line 131 connected to the reservoir 130, thus making it possible to limit the pressure of the fluid in the feed line 182 to the feed pressure.

[0031] In addition, the booster block 180 is designed to control the pressure regulation of the pump block 170 so as to bring the pressure of the fluid delivered by the pump block 170 into the delivery line 172, in other words the delivery pressure, to a value high enough to meet the operating needs of the lifting platform 1. More precisely, the pressure regulation is controlled by the booster block 180 taking into account at least the following three operating situations: in a first operating situation, where the lifting platform 1 is controlled to move the lifting structure 110 and / or to orient the wheels 11A and 11B, without being controlled to move in translation on the ground, in other words when at least one of the hydraulic actuators 20 and 120 is controlled in actuation without the hydraulic actuators 50, 70, 80 and 81 being controlled in actuation, the booster block 180 controls the pressure regulation so that the discharge pressure is greater than a load pressure of the actuator(s) which are controlled in actuation among the hydraulic actuators 20 and 120, this load pressure having a variable value, which depends on the work provided by this or these actuator(s) controlled in actuation to move the lifting structure 110 and / or orient the wheels 11A and 11B and which, in practice, can reach several dozens, even a few hundred bars;in a second operating situation, where the lifting platform 1 is controlled to move in translation on the ground, without being controlled to move the lifting structure 110 and / or orient the wheels 11A and 11B, in other words when the hydraulic actuator 50 and, where appropriate, at least one of the hydraulic actuators 70, 80 and 81 are controlled in actuation, without the hydraulic actuators 20 and 120 being controlled in actuation, the booster block 180 controls the pressure regulation so that the discharge pressure is greater than the booster pressure;and in a third operating situation, where the lifting platform 1 is, at the same time, controlled to move the lifting structure 110 and / or orient the wheels 11A and 11B and controlled to move in translation on the ground, in other words when at least one of the hydraulic actuators 20 and 120, as well as the hydraulic actuator 50 and, where appropriate, one of the hydraulic actuators 70, 80 and 81 are controlled in actuation, the booster block 180 controls the pressure regulation so that the discharge pressure is greater than the maximum between the load pressure and the booster pressure. ;

[0032] For this purpose, according to a preferred embodiment, both practical and economical, which is implemented at the figure 2 , the booster block 180 is connected to the hydraulic actuators 20 and 120 by a first load line 184, which is at the load pressure, and is connected to the pump block 170 by a second load line 185 which is connected to the inlet 176 of the regulator 174 of the pump block 170. Thus, the booster block 180 controls the pressure regulation of the pump block 170 by adjusting the discharge pressure to the pressure of the load line 185, increased by the pressure differential provided by the regulator 174. In addition, the booster block 180 comprises a solenoid valve 186, which is controlled by the control unit 150 and which is provided on a branch of the booster block 180, connecting the bypass supply line 181 and a pressure reducer 187 of the booster block. The pressure reducer 187 also connects the aforementioned branch of the feed block to the drainage line 131, thus making it possible to regulate the fluid pressure in this branch.In the non-actuated position, the solenoid valve 186 isolates the bypass supply line 181 from the pressure reducer 187, while in the actuated position, the solenoid valve 186 connects the bypass supply line 181 with the pressure reducer 187.The solenoid valve 186 is provided to be in the non-actuated position in the first operating situation and to be in the actuated position in the second and third operating situations: thus, when the hydraulic actuators 50, 70, 80 and 81 are not commanded to be actuated, the solenoid valve 186 prohibits the flow of fluid through it from the bypass supply line 181 to the pressure reducer 187, while when the hydraulic actuator 50 and, where appropriate, at least one of the hydraulic actuators 70, 80 and 81 are commanded to be actuated, the fluid from the bypass supply line 181 reaches, via the solenoid valve 186, the pressure reducer 187 which applies a reduction to the pressure of the bypass supply line 181. The booster block 180 also comprises a selector 188, which is connected to the outlet from pressure reducer 187 and to load lines 184 and 185.This selector 188 connects the load line 185 with the one between the outlet of the pressure reducer 187 and the load line 184, which has the highest pressure. In other words, the selector 188 sends to the load line 185 the fluid having the highest pressure between the fluid leaving the pressure reducer 187 and the fluid of the load line 184.

[0033] Based on the embodiment of the booster block 180, which has just been described and which is not, moreover, limiting, it is understood that the pressure of the load line 185 is controlled by the booster block 180 to be: the pressure of the load line 184, in the first operating situation, a reduction in the discharge pressure, in the second operating situation, and the maximum between the pressure of the load line 184 and the aforementioned reduction in the discharge pressure, in the third operating situation.

[0034] In practice, the aforementioned reduction in the discharge pressure, which is operated by the pressure reducer 187 in the embodiment illustrated in the figures, has a value fixed so that the boost pressure is smaller than the sum between the pressure differential and this reduction; for example, this reduction is approximately 15 bars. Therefore, the discharge pressure is, in the three aforementioned operating situations, brought by the pump unit 170 to a value sufficiently high to meet the operating needs of the lifting platform 1.

[0035] As an advantageous optional arrangement, the booster block 180 further comprises a solenoid valve 189 which is provided on a branch of the booster block 180, connecting the charging line 185 and the drainage line 131 connected to the tank 130. In the actuated position, the solenoid valve 189 isolates the charging line 185 and the drainage line 131 from each other, while, in the non-actuated position, the solenoid valve 189 puts them in communication with each other. The solenoid valve 189 is controlled by the control unit 150: in the three aforementioned operating situations, the control unit 150 switches the solenoid valve 189 to the actuated position.The interest of the solenoid valve 189 thus lies in another operating situation of the lifting platform 1, namely when the thermal engine 31 is switched on without, however, any of the hydraulic actuators 20, 50, 70, 80, 81 and 120 being actuated: in this case, although the pump unit 170 is driven by the thermal engine 31, its energy consumption remains very limited since the pressure of the load line 185 is substantially zero, which means that, by effect of the pressure regulation of the pump unit 170, the discharge pressure is limited to the aforementioned pressure differential. In the example mentioned above, the discharge line 172 is thus maintained at a pressure of approximately 20 bars, without working flow.

[0036] In order to control the actuation of the hydraulic actuators 20 and 120, the circulation circuit 140 comprises a main distribution block 190. This main distribution block 190 is, for the purposes of its fluid supply, connected to the delivery line 172 by a main supply line 191. As illustrated schematically in the figure 2 , the main distribution block 190 comprises, for each of the hydraulic actuators 20 and 120, a distributor 192 which controls the actuation of the hydraulic actuator concerned, by making it possible to send to this hydraulic actuator the fluid from the main supply line 191 when this hydraulic actuator is to be actuated, and by interrupting this sending of fluid when the hydraulic actuator is not to be actuated, where appropriate by evacuating excess fluid to the reservoir 130 via a drainage line 193. In practice, the respective embodiments of the distributors 192 are adapted to the actuator with which each of them is associated among the hydraulic actuators 20 and 120, these embodiments not being limiting. For example, the distributors 192 are solenoid valves, where appropriate with several ways and / or with N positions, N being greater than or equal to two.In all cases, the distributors 192 are controlled individually by the control unit 150 so as to allow the selective actuation of the hydraulic actuators 20 and 120, according to control instructions coming from the control unit 150. More generally, whatever the specificities of the distributors 192, the main distribution block 190 makes it possible to actuate the hydraulic actuators 20 and 120, by sending the fluid from the main supply line 191 selectively to the actuator(s) to be actuated among the hydraulic actuators 20 and 120. In practice, the locations where the distributors 192 are integrated in the lifting platform 1 are not necessarily grouped: for example, the distributor 192 associated with the hydraulic actuator 20 can be supported by the chassis 10 while the other distributors 192 are integrated into the lifting structure. 110.

[0037] In addition, the main distribution block 190 is connected to the booster block 180 by the load line 184. The main distribution block 190 is designed to, regardless of the actuator(s) that are controlled in actuation by the distributors 192 among the hydraulic actuators 20 and 120, set the load line 184 to the load pressure of this or these actuator(s) controlled in actuation. In practice, when several actuators among the hydraulic actuators 20 and 120 are simultaneously controlled in actuation, the load pressure in the load line 184 corresponds to the maximum value of the individual load pressures of these actuators controlled in actuation.One way to pressure the load line 184 at the highest load pressure of the hydraulic actuators 20 and 120 being controlled is to use pressure selectors between the lines connected to the hydraulic actuators, or valves between the lines connected to the hydraulic actuators and the load line 184.

[0038] In order to control the actuation of the hydraulic actuators 50, 70, 80 and 81, the circulation circuit 140 comprises an accessory distribution block 200. This accessory distribution block 200 is, for the purposes of its fluid supply, connected to the discharge line 172 by an accessory supply line 201.

[0039] The accessory distribution block 200 comprises a solenoid valve 202 which is controlled by the control unit 150. In the actuated position, the solenoid valve 202 makes it possible to send through it the fluid from the accessory supply line 201 to the hydraulic actuator 50 and thus to actuate the latter so as to activate the brake release device 40 as explained above. In the non-actuated position, the solenoid valve 202 isolates the hydraulic actuator 50 from the accessory supply line 201 and puts the hydraulic actuator 50 in communication with a drainage line 203 connecting the accessory distribution block 200 to the reservoir 130, which deactivates the brake release device 40, as explained above. The solenoid valve 202 thus makes it possible to control the actuation of the hydraulic actuator 50.

[0040] The accessory distribution block 200 also comprises a solenoid valve 204, which is similar to the solenoid valve 202, in particular being controlled by the control unit 150, but which, unlike the solenoid valve 202, makes it possible to control the actuation of the hydraulic actuator 70 and, thereby, the activation of the blocking device 60 presented above.

[0041] The accessory distribution block 200 also comprises two solenoid valves 205 and 206, which are controlled by the control unit 150 and which make it possible to control the actuation of the cylinders 80 and 81, while ensuring the feeding of these cylinders, whether the latter are actuated or not actuated, and this by using the fluid from the accessory supply line 201. This actuation of the cylinders 80 and 81 has been explained above, for the purposes of controlling the oscillation of the front axle 13A. According to considerations presented in detail in EP 3 792 213 to which the reader can refer, the respective inputs of the solenoid valves 205 and 206 are connected to each other by a branch of the accessory distribution block 200, connected to the accessory supply line 201 by a pressure reducer 207.

[0042] Thus, the accessory distribution block 200 is designed to control the actuation of the hydraulic actuators 50, 70, 80 and 81, by sending the fluid from the accessory supply line 201 selectively to the actuator(s) to be actuated among the actuators 50, 70, 80 and 81.It will be noted that, in addition to or in replacement of the hydraulic actuator 70, which provides the accessory function of activating the locking device 60, and in addition to or in replacement of the cylinders 80 and 81, which provide the accessory function of controlling the oscillation of the front axle 13A, one or more other hydraulic actuators can equip the lifting platform 1 to provide one or more other functions accessory to the operation of this lifting platform, by acting on corresponding accessory parts of the lifting platform, in a similar manner to the action of the hydraulic actuator 70 on the locking device 60 and to the action of the cylinders 80 and 81 on the front axle 13A.In this case, the accessory distribution block 200 comprises, for each of these additional hydraulic actuators, a distributor which is controlled by the control unit 150 and which controls the actuation of the hydraulic actuator concerned, making it possible to send to this hydraulic actuator the fluid from the accessory supply line 201 when this hydraulic actuator is to be actuated. Conversely, a variant not shown consists of limiting the accessory distribution block 200 to the solenoid valve 202, that is to say that, more generally, the accessory distribution block 200 can be limited to being able to control the actuation of the hydraulic actuator 50 for the purposes of activating the brake release device 40, insofar as the lifting platform 1 must always have the corresponding brake release function.In practice, the distributor(s) of the accessory distribution block 200 are integrated into the lifting platform 1 in respective locations which are not limiting and which are preferably adapted to the hydraulic actuator that each of them controls.

[0043] Following advantageous optional provisions, which are implemented at the figure 2 , the fluid leaving the feed block 180 via the feed line 182 is, in addition to being used by the accessory distribution block 200, used in connection with the hydrostatic transmission 32. For this purpose, the circulation circuit 140 comprises a compensation device 210 and a distributor 211, which are connected to the feed line 182 by a connection line 212 so as to be supplied with fluid by the feed line. The compensation device 210 is designed to introduce fluid into the closed circuit 35 to compensate for the losses of the latter. The compensation device 210 is, as such, known in the art, in particular in the field of lifting platforms, and will not be described further here.Whatever these specific embodiments, the compensation device 210 makes it possible, thanks to the fluid that it introduces into the closed circuit 35, to compensate for any leaks from this closed circuit, as well as to renew the fluid in the closed circuit by replacing withdrawals that are regularly made from the closed circuit 35, in particular by the scavenging valve 37 in order to renew and possibly cool the fluid in the closed circuit 35. The distributor 211 is, for its part, designed to act on the control member 36 which, as indicated above, makes it possible to adjust the displacement of the hydraulic pump 33. Here again, the distributor 211 in that it acts on the control member 36 is known as such and will therefore not be described here further, its embodiment not being limiting.

[0044] Taking into account the explanations given so far, the operation of the lifting platform 1 will be described by considering below different operating phases, which are frequently encountered in the field and which potentially follow one another, and this in any order. In all the operating phases considered below, the thermal engine 31 rotates and therefore drives the pump 173 of the pump unit 170.

[0045] In a first phase of operation, the operator of the lifting platform 1 does not give any control instructions to the lifting platform. The lifting platform 1 therefore remains stationary, in particular under the effect of the brake release device 40 which remains deactivated. The solenoid valves 186 and 189 are in the non-actuated position so that the pressure in the load line 185 is zero and, under the effect of the regulator 174, the discharge pressure at the outlet of the pump 173 is limited to the pressure differential mentioned above, i.e. for example 20 bars.

[0046] In a second operating phase, the operator gives instructions, in particular via the control panel 103, so that, without setting the lifting structure 110 in motion, the lifting platform 1 advances along the ground in a straight line, therefore without having to orient the wheels 11A to the left or to the right. The control unit 150 then switches the solenoid valves 186, 189 and 202 to the actuated position. The fluid in the discharge line 172, the pressure of which may initially be limited to the pressure differential, accesses, via the solenoid valve 186, the pressure reducer 187 and applies to the selector 188 the reduction, for example 15 bars, coming out of this pressure reducer 187. As the load pressure in the load line 184 is zero, the selector 188 allows the reduction to pass, which pressurizes the load line 185 to the value of this reduction.Under the effect of the regulator 174, the discharge pressure at the outlet of the pump 173 is brought to a value corresponding to the sum between the reduction and the pressure differential, that is to say, in the example considered so far, the sum between 15 bars and 20 bars. The fluid under this discharge pressure passes through the booster block 180 where the reducer 187 limits the pressure to the booster pressure, that is to say for example 27 bars, before reaching the accessory distribution block 200 via the accessory supply line 201. This fluid then passes through the solenoid valve 202 in the actuated position to actuate the hydraulic actuator 50 and thus activate the brake release device 40 to allow the lifting platform 1 to translate on the ground.

[0047] In a third operating phase, the operator gives instructions, in particular via the control panel 103, so that simultaneously the lifting platform 1 advances on the ground, if necessary by turning, and the lifting structure 110 moves the platform 100 relative to the chassis 10. The control unit 50 then switches or maintains the solenoid valves 186, 189 and 202 in the actuated position. The fluid in the delivery line 172 accesses, via the solenoid valve 186, the pressure reducer 187 and applies to the selector 188 the reduction, for example 15 bars, coming out of this pressure reducer 187.The selector 188 allows the fluid having the highest pressure between this reduction and the load pressure to pass into the load line 184, this load pressure being brought to a substantial value which depends on the work provided by one or more of the hydraulic actuators 120 controlled in actuation to act on the lifting structure 110, as well as, where appropriate, by the hydraulic actuator 20 to steer the wheels 11A and 11B to the left or to the right. In general, the value of this load pressure is greater than the reduction operated by the pressure reducer 187: it is considered here for example that the load pressure is worth a hundred bars. The load line 185 is pressurized with the fluid which the selector 188 allows to pass, that is to say to the aforementioned hundred bars.Under the effect of the regulator 174, the discharge pressure at the outlet of the pump 173 is brought to a value corresponding to the sum between the pressure differential and the pressure of the fluid in the load line 185, that is to say, here, the sum between 20 bars and the aforementioned hundred bars. The fluid under this discharge pressure is, on the one hand, sent to the main distribution block 190 to allow the actuation of the actuators 120 and optionally 20 to be actuated and, on the other hand, passes through the booster block 180 where the reducer 187 limits the pressure to the booster pressure, that is to say for example 27 bars, before reaching the accessory distribution block 200 where it actuates the hydraulic actuator 50 after passing through the solenoid valve 202 in the actuated position.

[0048] In a fourth operating phase, the operator gives instructions, in particular via the control panel 103, so that the lifting structure 110 moves the platform 100 relative to the chassis 10 and / or so that the wheels 11A are oriented to the left or to the right, without moving the chassis relative to the ground. The control unit 150 places or maintains the solenoid valve 189 in the actuated position and the solenoid valves 186 and 202 in the non-actuated position. Since the solenoid valve 202 is in the non-actuated position, all or part of the wheels 11A and 11B are blocked by the non-activated brake release device 40.Furthermore, since the pressure leaving the pressure reducer 187 is zero since the solenoid valve 186 isolates the latter from the bypass supply line 181, the selector 188 allows the fluid coming from the load line 184 to pass, which pressurizes the load line 185 to the value of the pressure of the load line 184, for example a hundred bars, as envisaged in the example above. Under the effect of the regulator 174, the discharge pressure at the outlet of the pump 173 is brought to a value corresponding to the sum between the pressure differential and the pressure in the load lines 184 and 185, that is to say, here, the sum between 20 bars and a hundred bars. The fluid under this discharge pressure is sent to the main distribution block 190 to enable the actuation of the actuator(s) 20 and / or 120 to be actuated and thus move the lifting structure 110.

[0049] It will be noted that in the various operating phases envisaged above, as well as in other potential operating phases, the control instructions given by the control unit 150 may, partially or totally, not result from instructions given by the operator via the control console 103, but from an automatic piloting unit which applies predetermined protocols, in particular protocols for securing the lifting platform 1.

[0050] On the figure 3 an alternative embodiment of the lifting platform 1 is shown, referenced 1'. The lifting platform 1' is identical to the lifting platform 1, except with regard to its motorization, referenced 30' instead of 30. The motorization 30' is distinguished from the motorization 30 by the fact that it is not based on a thermal engine, such as the thermal engine 31 of the lifting platform 1, but that it comprises one or more electric motors. In the embodiment considered in the figure 3 , the motorization 30' thus comprises two electric motors, namely an electric motor 31', the drive output of which is engaged with the gearbox 16 for the purpose of driving the wheels 11A and 11B of the lifting platform 1', and an electric motor 32', the drive output of which is engaged with the pump 173 for the purpose of driving the pump unit 170. More generally, it is understood that, whatever its specificities, the electric motorization 30' ensures, at the same time, the drive of the wheels 11A and 11B and the drive of the pump unit 170.

[0051] As a result, compared to the lifting platform 1, the lifting platform 1' is devoid of both a heat engine such as the heat engine 31 and an associated hydrostatic transmission such as the hydrostatic transmission 32, as well as hydraulic devices specific to such a hydrostatic transmission, such as the compensation device 210 and the distributor 211. For the rest, the lifting platform 1' has exactly the same components as the lifting platform 1, so that, on the figure 3 , the latter are identified with the same references as those used on the figure 2 . This illustrates the fact that the hydraulic system S presented in detail in the figure 2 can be used equally well for thermal and electric versions of the same lifting platform.

[0052] Finally, various arrangements and variants of the lifting platforms 1 and 1' that have been described so far can be envisaged. For example: within the lifting structure 110, the rotating turret 111 can be replaced by a fixed base; and / or as mentioned above, the elements belonging to the booster blocks 180, main distribution blocks 190 and accessory distribution blocks 200 are integrated into the lifting platform 1 in respective locations which are not limiting; this amounts to saying that the booster blocks 180, main distribution blocks 190 and accessory distribution blocks 200 which have been presented above are understood from a functional, and not a structural, point of view; thus, all or part of the functions of one of these blocks can be ensured by elements arranged in the same location as elements of another of these blocks, ensuring all or part of the functions of this other block.

Claims

1. An aerial lift (1; 1'), including: - a motor-drive (30; 30') by internal combustion engine or by electric motor, - a chassis (10) equipped with ground translation members (11A, 11B) which can be driven by the engine to move the chassis (10) with respect to the ground, - a platform (100) suitable for one operator standing thereon, - a lifting structure (110), which supports the platform (100) and which is arranged on the chassis (10) so as to be able to move the platform at height with respect to the chassis, and - a hydraulic system (S) comprising a reservoir (130), hydraulic actuators (20, 50, 70, 80, 81, 120) and a circulation circuit (140) through which fluid flows between the reservoir and the hydraulic actuators, the circulation circuit comprising: • a pump unit (170), which is connected to the reservoir (130) in such a way as to suck the fluid from the reservoir and which can be driven by the motor (30; 30') in such a way as to discharge the fluid into a discharge line (172) at a discharge pressure which is variable according to a pressure regulation, • a main manifold unit (190), which is connected to the discharge line (172) by a main supply line (191) and which controls the actuation of first actuators (20, 120) among the hydraulic actuators, selectively sending the main supply line fluid to the first actuator(s) to actuate, the first actuators including actuators (120) acting on portions of the lifting structure (110) so as to move the portions relative to the rest of the lifting structure or relative to the chassis (10), • a booster unit (180), which is connected to the discharge line (172) by a branched-off supply line (181) and which sends the fluid from the branched-off supply line into a booster line (182) by regulating the pressure thereof to a booster pressure the value of which is preset, and • an accessory manifold unit (200), which is connected to the booster line (182) by an accessory supply line (201) and which controls the actuation of one or a plurality of second actuators (50, 70, 80, 81) among the hydraulic actuators, by selectively sending fluid from the accessory supply line to the at least one second actuator to actuate, the second actuator(s) being distinct from the first actuators (20, 120) and acting on accessory portions (40, 60, 13A) of the aerial lift (1; 1'), the or one of the second actuators (50) thereby acting on a brake release device (40) which, in the non-activated state, brakes at least some of the ground translation members (11A, 11B), wherein the booster unit (180) controls said pressure regulation in such a way that: - when at least one of the first actuators (20, 120) is actuated without the second actuator(s) (50, 70, 80, 81) being actuated, the discharge pressure is higher than a load pressure of the first actuator(s) actuated, the value of which depends on the work provided by the first actuated actuator(s) controlled, - when the or at least one of the second actuators (50, 70, 80, 81), including the actuator acting on the brake release device (40), is actuated without the first actuators (20, 120) being actuated, the discharge pressure is higher than the load pressure, and - when at least one of the first actuators (20, 120) and the or at least one of the second actuators (50, 70, 80, 81), including the actuator acting on the brake release device (40), are actuated, the discharge pressure is higher than the maximum between the load pressure and the load pressure.

2. The aerial lift according to claim 1, wherein the booster unit (180) is connected to the main manifold unit (190) by a first load line (184) which is at the load pressure, and is connected to the pump unit (170) by a second load line (185), the pressure of which is controlled by the booster unit (180) so as to be: - the pressure of the first load line when at least one of the first actuators (20, 120) is actuated without the second actuator(s) (50, 70, 80, 81) being actuated, - a reduction of the discharge pressure when the or at least one of the second actuators (50, 70, 80, 81), including the actuator acting on the brake release device (40), is actuated without the first actuators (20, 120) being actuated, and - the maximum between the pressure of the first load line and said reduction of the discharge pressure when at least one of the first actuators (20, 120) and the or at least one of the second actuators (50, 70, 80, 81), including the actuator acting on the brake release device (40), are actuated, and wherein the booster unit (180) controls the pressure regulation of the pump unit (170) by adjusting the discharge pressure to the pressure of the second load line (185), increased by a constant pressure differential.

3. The aerial lift according to claim 2, wherein the booster unit (180) includes: - a pressure reducer (187) which regulates the pressure of the fluid passing therethrough to said reduction of the discharge pressure, - a solenoid valve (186) which: • puts the branched-off supply line (181) in communication with the pressure reducer (187) when the or at least one of the second actuators (50, 70, 80, 81), including the actuator acting on the brake release device (40), are actuated, and • isolates the branched-off supply line (181) from the pressure reducer (187) when the second actuator or actuators are not actuated, and - a selector (188) which sends to the second load line (185) the fluid having the highest pressure between the fluid leaving the pressure reducer (187) and the fluid from the first load line (184).

4. The aerial lift according to any one of preceding claims, wherein the booster unit (180) includes a pressure reducer (183) which connects the branched-off supply line (181) and the booster line (182) and which regulates the pressure of the fluid passing therethrough to the booster pressure.

5. The aerial lift according to any one of preceding claims, wherein the pump unit (170) includes: - a variable displacement pump (173), which sucks in the fluid from the reservoir (130) and which discharges the fluid into the discharge line (172), and - a regulator (174), which implements said pressure regulation and which acts on a control member (175), such as a cylinder, controlling the displacement of the pump.

6. The aerial lift according to any one of preceding claims, wherein the ground connecting members (11A, 11B) are distributed in at least two pairs of ground connecting members, the two ground connecting members (11A, 11B) of each pair are carried by the opposite ends, respectively, of the same drive axle (12A, 12B) and form with the latter an axle (13A, 13B) of the chassis (10).

7. The aerial lift according to claim 6, wherein at least one of the drive axles (12A, 12B) comprises a drive shaft (14A, 14B) which transmits the drive from the motor-drive (30; 30') to the ground translation members (11A, 11B) supported by the drive axle and which includes a differential (15A, 15B), and wherein the second actuators (50, 70, 80, 81) include, for the or at least one of the differentials (15A, 15B), an actuator (70) acting on a locking device (60) which, in the activated state, locks the differential concerned.

8. The aerial lift according to one of claims 6 or 7, wherein the or at least one of the axles (13A, 13B) is oscillating, and wherein the second actuators (50, 70, 80, 81) include, for the or each oscillating axle, cylinders (80, 81) which bear on the drive axle (12A, 12B) concerned so as to control the oscillation thereof.

9. The aerial lift according to any one of the preceding claims, wherein the first actuators include at least one actuator (20) acting on the orientation of at least some of the ground translation members (11A, 11B) relative to the frame (10) to change the direction along which the chassis translates on the ground.

10. The aerial lift according to any one of the preceding claims, wherein the motor (30) includes an internal combustion engine (31) which is mechanically connected to the pump unit (170) to drive the latter, wherein the hydraulic system (S) comprises a hydrostatic transmission (32) having a hydraulic pump (33), which is mechanically connected to the internal combustion engine (31), a hydraulic motor (34), which is mechanically connected to the ground translation members (11A, 11B) for driving the latter, and a closed circuit (35) wherein fluid flows between the hydraulic pump and the hydraulic motor, and wherein the circulation circuit (140) includes a compensation device (210), which is suitable for feeding fluid into the closed circuit (35) to compensate for losses, the compensation device being connected to the booster line (182).

11. The aerial lift according to claim 10, wherein the hydraulic pump (33) has a variable displacement, and wherein the circulation circuit (140) includes a directional control valve (211) which acts on a control member (36), such as a cylinder, controlling the displacement of the hydraulic pump (33), the directional control valve being connected to the load line (182).

12. The aerial lift according to any one of claims 1 to 9, wherein the motor (30') comprises one or a plurality of electric motors (31', 32') which drive both the ground translation members (11A, 11B) and the pump unit (170).