Aerial work platform and method for controlling an aerial work platform

Description

[0001] The present invention relates to a lifting platform, as well as to a method of controlling such a platform.

[0002] The invention relates more specifically to cradles whose components of the lifting structure are moved by hydraulic actuators that the user actuates by means of a fluid, typically oil, which circulates in a hydraulic circuit under the effect of an electrically driven pump. This type of cradle, whose movement on the ground is generally also operated by an electric motor, thus comprises an electric motor pump, which sucks the fluid from a reservoir of the hydraulic system and which forces the fluid into the hydraulic circuit to circulate it to the hydraulic actuators.

[0003] When the user commands the actuation of one of the hydraulic actuators, all or part of the fluid delivered by the motor pump is sent to the relevant actuator in order to actuate it. The actuation speed of the actuator and therefore the speed of movement of the corresponding part of the lifting structure of the nacelle are directly linked to the flow rate of the fluid supplying the actuator, so that when the user commands the actuation of the hydraulic actuator with a high speed, the motor pump can, if necessary, be controlled to increase its delivery rate. In addition, each hydraulic actuator of the nacelle can be associated with a proportional solenoid valve which takes from the flow of fluid delivered by the motor pump a flow of fluid which is sent to the actuator, being adjusted to the need for the actuation of this actuator.In all cases, the fraction of the discharge flow, not used by the hydraulic actuator, is returned directly to the tank. It is understood that, thanks to the different proportional solenoid valves, the user can simultaneously actuate two actuators and thus operate in parallel two movements of different respective parts of the lifting structure, provided that the discharge flow is sufficient to cover the respective needs of the two actuations. That being said, the presence of these different proportional solenoid valves makes the hydraulic circuit complex and expensive, which is not always desirable for certain types of platforms, in particular platforms of limited size.

[0004] In the absence of such proportional solenoid valves, it may be possible to allow the user to operate two hydraulic actuators simultaneously, but the fluid may then flow mainly towards the one of the two actuators which offers the least resistance. This leads to movements of the lifting structure which are dangerous, because they are imprecise and difficult to control, since these movements depend, among other things, on the configuration of the lifting structure and the load on board the platform.

[0005] For its part, JP 2002 326799 discloses a lifting platform vehicle according to the preamble of claim 1. This vehicle comprises a lifting structure actuated by hydraulic actuators which are respectively associated with control levers. The hydraulic actuators are supplied with fluid by a pump driven by an electric motor which is controlled by an electronic circuit belonging to a controller. The electronic circuit is designed to calculate the fluid flow rates respectively required by the hydraulic actuators as a function of the actuation of the latter by the control levers. In particular, when several of the control levers are actuated simultaneously, the circuit adds up the flow rates respectively required to actuation of the respectively corresponding hydraulic actuators.Based on the total flow rates required, the electronic circuit drives the electric motor so that the pump delivers the fluid with a flow rate that at least covers the needs of the actuators actually operated. In order to distribute the fluid delivered by the pump between the various hydraulic actuators, the vehicle's hydraulic system includes an electromagnetic regulation assembly, with proportional opening, which is controlled by a dedicated circuit that is connected to the aforementioned control levers.

[0006] The aim of the present invention is to propose an improved lifting platform, which, while having a simple and inexpensive hydraulic system, allows the simultaneous movement of two different parts of its lifting structure to be carried out in a controlled manner.

[0007] To this end, the invention relates to a lifting platform as defined in claim 1.

[0008] The invention also relates to a method for controlling a lifting platform, as defined in claim 12.

[0009] One of the ideas underlying the invention is, from the flow of fluid delivered by the electric motor pump, to be able to circulate the fluid to the hydraulic actuators with a precise flow rate, which is adjusted to the needs of the actuation of the one or two hydraulic actuators and which is distributed in a regulated manner with respect to this or these two actuators. To do this, the hydraulic actuators of the nacelle according to the invention are divided into two groups of one or more actuators.In addition, when the operator commands the actuation of the or one of the actuators of the first group and / or the actuation of the or one of the actuators of the second group, a first target flow rate for the actuation requirement of the first group and a second target flow rate for the actuation requirement of the second group are determined, it being understood that the second target flow rate is zero in the case where the operator commands the actuation of the or one of the actuators only of the first group, and it being understood that the first target flow rate is zero in the case where the operator commands the actuation of the or one of the actuators only of the second group. In all cases, the motor pump is controlled so that its discharge flow rate, that is to say the flow rate of the fluid leaving the motor pump under the effect of the discharge generated by the latter, is equal to or greater than the sum of the first and second target flow rates.The invention then provides that a regulated proportion of the fluid delivered by the motor pump is sent jointly to the first and second groups, this regulated proportion having a controlled flow rate which is equal to the sum of the first and second target flow rates. The invention then provides that this regulated proportion is divided into two adjusted parts, which respectively have the first and second target flow rates and which are respectively sent to the first group and to the second group to actuate the two hydraulic actuators concerned, and this with precision and in accordance with the operator's command.In practice, the corresponding flow regulation and distribution operations are carried out respectively by a flow regulation device and, downstream of the latter, a flow distribution device, which belong to ad hoc flow control means, controlled by an appropriate control unit, typically a computer integrated into the nacelle, this control unit also ensuring the determination of the first and second target flow rates, as well as the control of the motor pump. As detailed below, the aforementioned flow control means can have a particularly simple and inexpensive embodiment.In all cases, the invention makes it possible to simultaneously move two different parts of the lifting structure of the nacelle and therefore increase the productivity of this nacelle, while precisely controlling the reliability of the two corresponding movements so that they respond to the control instructions given by the user of the nacelle. The invention does not, however, require hydraulic equipment that would be numerous and / or complex, and therefore expensive. In particular, each hydraulic actuator does not have to be associated with a proportional solenoid valve for the purposes of controlling its actuation. Similarly, the motor pump of the nacelle according to the invention can be of simple and inexpensive technology, in particular by being of fixed displacement, the pump of this motor pump being for example a gear pump.The invention thus finds a preferential, but non-limiting, application to lifting cradles, which are self-propelled and have an exclusively electric primary energy source, in particular having a power of between 2 and 15 kW, and / or to lifting cradles whose platform elevation height is moderate, in particular less than 16 m.

[0010] Advantageous optional features 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: [ Fig. 1 ] there figure 1 is an elevation view of a lifting platform according to the invention; and [ Fig. 2 ] there figure 2 is a diagram of some components of the nacelle of the figure 1 , in particular a hydraulic system of the latter.

[0012] On the figures 1 And 2 a 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. The chassis 10 is provided with wheels for its translation on the ground. In the exemplary embodiment considered in the figures, these wheels are divided into a pair of rear wheels 11 and a pair of front wheels 12.

[0014] The wheels of at least one of the two pairs of wheels 11 and 12 are steered, being tiltable 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 steered wheels 11 and / or 12 makes it possible to rotate the chassis 10 correspondingly relative to the ground. The steered wheels 11 and / or 12 can thus be oriented in an adjustable manner relative to the chassis 10 in order to steer the lifting platform 1 on the ground along a trajectory controlled by the operator using the lifting platform 1. For this purpose, in the exemplary embodiment considered in the figures and as indicated schematically in the figure 2 , the chassis 10 comprises a hydraulic directional control device 13 which acts on the steered wheels 11 and / or 12 so as to adjust their orientation relative to the chassis 10. The hydraulic directional control device 13 is, as such, known in the art, in particular in the field of lifting platforms, so that the embodiment of this device is not limiting.

[0015] In a variant not shown, all or part of the rear wheels 11 and the front wheels 12 can be replaced by tracks for the purpose of translating the chassis 10 on the ground. More generally, the rear wheels 11 and the front wheels 12 are only examples of ground translation members which equip the chassis 10.

[0016] Whatever the specific features of the ground translation members, such as the rear wheels 11 and front wheels 12, the chassis 10 is advantageously designed to be self-propelled so as to be able to move on the ground by itself. For this purpose, the chassis 11 incorporates transmission members, which drive at least some of the aforementioned ground translation members, for example the rear wheels 11 and / or the front wheels 12. These transmission members, which are not shown in the figures, are known in the field of self-propelled platforms, being for example mechanical and / or hydraulic and / or electrical in nature. In all cases, these transmission members are themselves driven by a motorization 14 which is advantageously integrated into the chassis 10, as shown schematically in the figure 1 . According to a preferred embodiment, the motorization 14 is electric.

[0017] The lifting platform 1 also comprises a platform 20 which is designed so that the operator using the lifting platform can stand thereon. The platform 20 is thus designed to accommodate this operator on board, as well as, where appropriate, one or more other persons and / or equipment for carrying out work at height. For this purpose, the platform 20 comprises a floor 21, on which the operator stands, and a guardrail 22 which rises from the floor 21 surrounding the platform 20. In addition, the platform 20 is provided with a control panel 23 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 30 of the lifting platform 1, supporting the platform 20.

[0018] The lifting structure 30 is arranged on the chassis 10 so as to more or less raise the platform 20 relative to the chassis 10. For this purpose, the lifting structure 30 comprises a turret 31, which rests on the chassis 10 and which is rotatable relative to the latter around an axis of rotation extending perpendicular to the ground, and an arm 32, which connects the turret 31 to the platform 20 and which is deployable so as to more or less separate the platform 20 from the turret 31.

[0019] The embodiment of the turret 31 is not limiting. Similarly, the embodiment of the arm 32 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 purpose of deploying this mechanical structure. In the exemplary embodiment considered in the figures, the arm 32 is an articulated arm which, as clearly visible in the figure 1 , includes a lower arm element 32.1, forming a pantograph whose lower end is articulated on the turret 31, an intermediate arm element 32.2, forming a boom which is articulated on the upper end of the pantograph, and an upper arm element 32.3, forming a pendulum whose one end is articulated on the boom while the opposite end supports the platform 20. The relative movements permitted by the arm elements 32.1, 32.2 and 32.3 are known per se and will not be described further, the reader being able for example to refer to FR 3 067 341. In a variant not shown, the arm 32 is at least partially telescopic, including arm elements which fit into each other.

[0020] More generally, the embodiment of the lifting structure 30 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 20 relative to the chassis 10 is modified in a corresponding manner, the platform 20 thus being controlled in movement, by means of the lifting structure 30, by the operator using the lifting platform 1.

[0021] Whatever the shape of the lifting structure 30, the movable parts of the latter are driven in displacement relative to each other and / or relative to the chassis 10 by hydraulic actuators which are integrated into the lifting platform 1. Thus, in the embodiment considered here, these hydraulic actuators act on the turret 31 for the purpose of its rotation around the aforementioned axis of rotation relative to the chassis 10, as well as on the arm 32 for the purpose of its deployment relative to the turret, in particular on the arm elements of the arm 32 for their displacement relative to each other. Such hydraulic actuators are known per se in the field of lifting platforms and the embodiment of each of them is not limiting of the invention. Thus, each of the aforementioned hydraulic actuators can be, for example, a single-acting cylinder, a double-acting cylinder, a rotary actuator, etc.Whatever their form of embodiment, the aforementioned hydraulic actuators are, as shown diagrammatically in the . figures 2 , divided into two groups, namely a group G1 consisting of one or more of these hydraulic actuators, the actuator(s) of group G1 being referenced 41, and a group G2 consisting of the rest of the aforementioned hydraulic actuators, the actuator(s) of group G2 being referenced 42. In the exemplary embodiment considered in the figures, group G1 includes several actuators 41 and group G2 also includes several actuators 42, as indicated schematically in the figure 2 .

[0022] The fact of distributing the hydraulic actuators of the lifting platform 1, which act on respective parts of the lifting structure 30 for the purpose of moving the latter, presents an advantage which will appear in more detail later and which is linked to the possibility for the operator using the lifting platform 1 to actuate in a controlled manner simultaneously one of the actuators 41 of the group G1 and one of the actuators 42 of the group G2 and therefore, thereby, to drive the lifting structure 30 simultaneously according to two movements, by moving the two parts of this lifting structure on which the actuated actuator 41 and the actuated actuator 42 act respectively.In practice, the way of distributing the hydraulic actuators of the lifting platform 1, which act on the lifting structure 30, between the groups G1 and G2 is not limiting of the invention and can be the subject of multiple variants, according to the specificities and choices of operation of the lifting structure 30. By way of non-limiting example, in the embodiment considered in the figures, the lower arm element 32.1 and the upper arm element 32.3 are actuable by two of the actuators 41 of the group G1, while the intermediate arm element 32.2 is actuated by one of the actuators 42 of the group G2, as indicated in the . figure 1 .

[0023] In order to operate the actuators 41 and 42, the lifting platform 1 comprises a hydraulic system S, which is shown in figure 2 and which will be detailed below, as well as a control unit 50 for controlling the hydraulic system S. In practice, the control unit 50 comprises a computer or similar electronic components and is connected and controlled to the control panel 23 of the platform 20 by arrangements of the lifting platform 1, which are known per se and which will not be detailed here further.

[0024] The control unit 50 is adapted to determine, at the same time, a first target flow rate Q1 as a function of a command made by the operator using the lifting platform 1 and intended for one of the actuators 41 of the group G1 and a second target flow rate Q2 as a function of a command made by this operator and intended for one of the actuators 42 of the group G2. Thus, when the operator orders one of the actuators 41 to be actuated, by acting on an ad hoc control element of the control panel 23, the control unit 50 calculates the first target flow rate Q1 as being the fluid flow rate that it is necessary to send to the actuator 41 concerned to move the corresponding part of the lifting structure 30 according to the command applied by the operator.This fluid flow rate depends, among other things, on the speed of movement of the lifting structure 30, which is controlled by the operator: the greater the speed of this movement controlled by the operator, the greater the fluid flow rate to be sent to the actuator 41 concerned. Similarly, when the operator orders one of the actuators 42 to be actuated, by acting on another ad hoc control element of the control panel 23, the control unit 50 calculates the second target flow rate Q2 as being the fluid flow rate that it is necessary to send to the actuator 42 concerned to move the corresponding part of the lifting structure 30 according to the command applied by the operator. Of course, when the user commands the actuation of one of the actuators 41 without actuating the actuators 42, the second target flow rate Q2 is zero. Similarly, when the operator commands the actuation of one of the actuators 42 without actuating the actuators 41, the first target flow rate Q1 is zero.When the operator simultaneously commands the actuation of one of the actuators 41 and the actuation of one of the actuators 42, the target flow rates Q1 and Q2 are both unaffected.

[0025] The hydraulic system S comprises a circulation circuit 60 through which a fluid, typically oil, circulates between a reservoir 70 of the hydraulic system S and the actuators 41 and 42. This circulation circuit 60 comprises, among other things, fluid flow lines, connecting the various components of the hydraulic system to each other and / or to the actuators 41 and 42, as illustrated by the figure 2 In practice, these circulation circuit lines 60 are produced by pipes, where appropriate flexible, integrated into the lifting platform 1. The tank 70 is preferably integrated into the chassis 10, the embodiment of this tank 70 not being limiting.

[0026] The S hydraulic system also includes an 80 motor pump which, as illustrated in the figure 2 , sucks the fluid from the reservoir 70 and delivers it into the circulation circuit 60 to circulate this fluid therein. The motor pump 80 is electric and thus includes a pump 81 and an electric motor 82 which drives the pump 81. The motor pump 80 is designed to be controlled by the control unit 50 so that, in operation, the motor pump 80 delivers the fluid into the circulation circuit 60 with a delivery flow rate QR which is greater than or equal to the sum of the first target flow rate Q1 and the second target flow rate Q2. The control unit 50 is thus adapted to control the electric motor 82, in particular to control the speed at which this electric motor 82 drives the pump 81 so that the latter delivers the fluid into the circulation circuit 60 with the delivery flow rate QR.

[0027] According to a practical and economical embodiment, the pump 81 has a fixed displacement. As a result, the delivery flow rate QR is proportional to the speed at which the electric motor 82 drives the pump 81. The fixed displacement pump 81 is preferably a gear pump, which has the advantage of being reliable, robust and inexpensive, but which requires that the speed at which it is driven is not too low in order to maintain good internal lubrication and, therefore, a long service life. In this embodiment, the pump 81 is therefore designed to be driven by the electric motor 82 at a predetermined minimum speed at which the pump 81 delivers the fluid into the circulation circuit 60 with a minimum value for the delivery flow rate QR.Furthermore, the control unit 50 is then adapted to not control the driving of the pump 81 below the predetermined minimum speed, whatever the values ​​of the first target flow rate Q1 and the second target flow rate Q2. It is understood that, when the control unit 50 calculates that the sum of the target flow rates Q1 and Q2 is less than the minimum value of the delivery flow rate QR, associated with the aforementioned predetermined minimum speed, the control unit 50 controls the driving of the pump 81 at the predetermined minimum speed, so that the delivery flow rate QR at the outlet of the motor pump 80 is equal to the aforementioned minimum value and is therefore greater than the sum of the flow rates Q1 and Q2.On the other hand, when the sum of the flow rates Q1 and Q2 determined by the control unit 50 is equal to or greater than the minimum value associated with the aforementioned predetermined minimum speed, the control unit 50 controls the motor pump 80 so that the discharge flow rate QR at the outlet of the motor pump 80 is equal to the sum of the target flow rates Q1 and Q2.

[0028] The hydraulic system S further comprises flow control means 90 for controlling the flow of fluid in the circulation circuit 60 between, on the one hand, the reservoir 70 and, on the other hand, the actuators 41 of the group G1 and the actuators 42 of the group G2. These flow control means 90 are controlled by the control unit 50 and are adapted, by means of their control by the control unit 50, to both jointly send to the groups G1 and G2 a regulated proportion of the fluid delivered by the motor pump 80, this regulated proportion having a controlled flow rate Q0 equal to the sum of the first target flow rate Q1 and the second target flow rate Q2, and then to divide this regulated proportion into two adjusted parts, which respectively have the first target flow rate Q1 and the second target flow rate Q2 and which are respectively sent to the group G1 and to the group G2.It is understood that when the discharge flow rate QR at the outlet of the motor-pump 80 is equal to the sum of the target flow rate Q1 and the target flow rate Q2, the flow control means 90 are controlled so that the controlled flow rate Q0 is equal to the discharge flow rate QR, which is equivalent to saying that the aforementioned regulated proportion corresponds to the entire flow discharged by the motor-pump 80. Conversely, when the discharge flow rate QR at the outlet of the motor-pump 80 is greater than the sum of the target flow rates Q1 and Q2, the flow control means 90 are controlled so that the controlled flow rate Q0 is equal to only a fraction of the discharge flow rate QR, which is equivalent to saying that the aforementioned regulated proportion corresponds to only a part of the flow discharged by the motor-pump 80.

[0029] The flow control means 90 comprise a flow regulating device 91 and a flow distributing device 92, which are arranged in series between the motor pump 80 and the actuators 41 and 42, the flow distributing device 92 being downstream of the flow regulating device 91 with respect to the flow delivered by the motor pump 80. This embodiment is practical and economical.

[0030] The flow control device 91 has three paths, namely: an inlet channel 91A which receives the entire flow leaving the motor pump 80 via a line 61 of the circulation circuit 60, this line 61 connecting the discharge of the motor pump 80 to the inlet of the flow regulation device 91, a main outlet channel 91B which sends the fluid leaving the flow regulation device 91 to the flow distribution device 92, via a line 62 of the circulation circuit 60, and a secondary outlet channel 91C which sends the fluid leaving the flow regulation device 91 directly to the reservoir 70, via a line 63 of the circulation circuit 60.

[0031] The flow control device 91 is adapted to regulate the flow of fluid from the inlet port 91A to the main 91B and secondary 91C outlet ports, being controlled by the control unit 50 so that the main outlet port 91B receives the aforementioned regulated proportion of the fluid delivered by the motor pump 80 while an excess of the fluid delivered by the motor pump is discharged via the secondary outlet port 91C, this excess having a flow rate equal to the difference between the delivery flow rate QR and the controlled flow rate Q0, it being recalled that the controlled flow rate Q0 is equal to the sum of the target flow rates Q1 and Q2.Thus, when the discharge flow rate QR is equal to the sum of the target flow rates Q1 and Q2, the flow rate of the fluids in the secondary outlet channel 91C is zero, while when the discharge flow rate QR is strictly greater than the sum of the target flow rates Q1 and Q2, the flow rate of fluid in the secondary outlet channel 91C is non-zero, being equal to the difference between the discharge flow rate QR and the sum of the target flow rates Q1 and Q2.

[0032] In order to perform the flow regulation just described, the flow regulation device 91 is designed, in a particularly ingenious and inexpensive embodiment, to include a proportional solenoid valve 91.1 and a pressure compensator 91.2, as illustrated in the figure 2 The proportional solenoid valve 91.1 is adapted to control the flow of fluid from the inlet port 91A to the main outlet port 91B, allowing this flow with a controlled passage cross-section or interrupting this flow, according to a pilot signal emitted by the control unit 50 based on the sum of the target flow rates Q1 and Q2. The pressure compensator 91.2 is adapted to connect the upstream side of the proportional solenoid valve 91.1 to the secondary outlet port 91C according to a connection ratio that is a function of the pressure differential between the upstream and downstream sides of the proportional solenoid valve 91.1. Thus, when the control unit 50 determines that it is operating the motor pump 80 in such a way that the discharge flow rate QR is equal to the sum of the target flow rates Q1 and Q2, the control unit 50 causes the passage section of the proportional solenoid valve 91 to be fully opened.1: in this case, the pressure difference between the upstream and downstream of the proportional solenoid valve 91.1 is almost zero, so that the pressure compensator 91.2 keeps the connection between the upstream of the proportional solenoid valve 91.1 and the secondary outlet channel 91C closed, under the effect of an ad hoc spring, integrated into the pressure compensator 91.2. When the control unit 50 determines that it is operating the motor pump 80 in such a way that the discharge flow rate QR is strictly greater than the sum of the target flow rates Q1 and Q2, the control unit 50 only partially opens the passage section of the proportional solenoid valve 91.1, with an opening proportion corresponding substantially to the fraction represented by the share of the sum of the target flow rates Q1 and Q2 with respect to the discharge flow rate QR: in this case, the upstream of the proportional solenoid valve 91.1 presents an overpressure with respect to the downstream of this proportional solenoid valve, so that the pressure compensator 91.2 opens the connection between the upstream of the proportional solenoid valve 91.1 and the secondary outlet path 91C, until equilibrium is reached between the pressure upstream of the proportional solenoid valve 91.1 and the pressure downstream of this proportional solenoid valve, supplemented by the load of the spring integrated into the pressure compensator 91.2.

[0033] In the embodiment shown in the figures, the flow control device 91 also includes an on / off solenoid valve 91.3, which is adapted to control the communication of a spring chamber of the pressure compensator 91.2 with the reservoir 70, by enabling or interrupting this communication, depending on a pilot signal emitted by the control unit 50. The on / off solenoid valve 91.3 can thus be provided normally open, so that, as long as the control unit 50 does not command its closure, the spring chamber of the pressure compensator 91.2 communicates freely with the secondary outlet 91C, via the on / off solenoid valve 91.3, thus allowing a near-zero pressure in the spring chamber of the pressure compensator 91.2. Under the effect of the motor pump 80, the pressure rises in line 61 up to the load value of the spring of the pressure compensator 91.2, which causes the pressure compensator 91.2 to switch to allow the flow of the flow delivered by the motor pump 80 from the inlet port 91A to the secondary outlet port 91C, via the pressure compensator 91.2. The pressure in the inlet port 91A cannot exceed the value corresponding to the load of the spring of the pressure compensator 91.2. In steady state, as soon as the lifting structure 30 is to be moved, the control unit 50 commands the closing of the on-off solenoid valve 91.3, which interrupts the communication between the spring chamber of the pressure compensator 91.2 and the secondary outlet port 91C. The pressure in the spring chamber of the compensator 91.2 is then equal to the pressure of the main outlet port 91B, allowing normal operation of the pressure compensator 91.2, as described above.The pressure in the intake tract 91A is no longer limited to the value corresponding to the spring load of the pressure compensator 91.2.

[0034] Also in the embodiment considered in the figures, the flow control device 91 comprises an all-or-nothing distributor 91.4, which is adapted to send the fluid from downstream of the proportional solenoid valve 91.1 to the hydraulic directional control device 13, being controlled by the control unit 50. The all-or-nothing distributor 91.4 is, for example, a four-way, three-position distributor. The all-or-nothing distributor 91.4 makes it possible to divert, to the hydraulic directional control device 13, the flow from the main outlet channel 91B, depriving the flow distribution device 92 thereof. In this way, the hydraulic system S is used to, when it is not used to actuate the actuators 41 and 42, actuate the hydraulic directional control device 13 and thus make it possible to orient the movement path of the lifting platform 1 on the ground.The lifting platform 1 thus avoids having, in addition to the hydraulic system S, another hydraulic system which would be dedicated to the actuation of the hydraulic directional control device 13.

[0035] Furthermore, the arrangement of the all-or-nothing solenoid valve 91.3 and the all-or-nothing distributor 91.4 in the flow control device 91 is of practical and economic interest, in particular by providing that this flow control device 91 is integrated into the chassis 10.

[0036] For its part, the flow distribution device 92 has three paths, namely: an inlet channel 92A, which receives the fluid from the main outlet channel 91B of the flow regulating device 91, via the line 62, and which is thus, in service, supplied by the regulated proportion, having the controlled flow rate Q0, of the fluid delivered by the motor pump 80, a first outlet channel 92B, sending the fluid to the actuators 41 of the group G1, via a line 64 of the circulation circuit 60, and a second outlet channel 92C which sends the fluid to the actuators 42 of the group G2, via a line 65 of the circulation circuit 60.

[0037] The flow distribution device 92 is adapted to distribute all the fluid of the inlet channel 92A between the first outlet channel 92B and the second outlet channel 92C, being controlled by the control unit 50 so that the first outlet channel 92B receives an adjusted part of the aforementioned regulated proportion, having the target flow rate Q1, and that the second outlet channel 92C receives the remainder of the regulated proportion, in other words an adjusted part of the latter, having the target flow rate Q2.

[0038] Thus, when one of the actuators 41 of group G1 is actuated while none of the actuators 42 of group G2 are actuated, the control unit 50 directs the entire flow from input channel 92A to the first output channel 92B, via the flow distribution device 92. Similarly, when one of the actuators 42 of group G2 is actuated while none of the actuators 41 of group G1 is actuated, the control unit 50 directs the entire flow from input channel 92A to the second output channel 92C, via the flow distribution device 92. When one of the actuators 41 of group G1 and one of the actuators 42 of group G2 are actuated simultaneously, the control unit 50 distributes the flow from input channel 92A between output channels 92B and 92C, via the flow distribution device 92, with a distribution key corresponding to the respective proportions of the target flow Q1 and the target flow Q2.

[0039] In order to carry out the flow distribution which has just been described, the flow distribution device 92 comprises, according to a particularly clever and inexpensive embodiment, a proportional solenoid valve 92.1 and a pressure compensator 92.2, as illustrated in the figure 2. The proportional solenoid valve 92.1 is adapted to control the flow of the fluid from the inlet port 92A to the first outlet port 92B, by allowing this flow with a controlled passage section or by interrupting this flow, depending on a control signal that the control unit 50 emits from the respective values ​​of the target flow rates Q1 and Q2. The pressure compensator 92.2 is adapted to connect the upstream of the proportional solenoid valve 92.1 to the second outlet port 92C and to connect the downstream of this proportional solenoid valve to the first outlet port 92B according to respective inverse connection proportions which are a function of the pressure differential between the upstream and downstream of the proportional solenoid valve 92.1.Thus, when one of the actuators 41 of the group G1 is actuated while none of the actuators 42 of the group G2 is actuated, the control unit 50 causes the passage section of the proportional solenoid valve 92.1 to open completely: in this case, there is no pressure difference between the upstream and downstream of this proportional solenoid valve 92.1, so that the pressure compensator 92.2 keeps the connection between the upstream of this solenoid valve and the outlet port 92C completely closed while keeping the connection between the downstream of this solenoid valve and the outlet port 92B completely open, under the effect of an ad hoc spring, integrated into the pressure compensator 92.2. When one of the actuators 42 of group G2 is actuated while none of the actuators 41 of group G1 is actuated, the control unit 50 completely closes the passage section of the proportional solenoid valve 92.1: in this case, the upstream of the proportional solenoid valve 92.1 presents an overpressure with respect to the downstream of this solenoid valve, so that the pressure compensator 92.2 fully opens the connection between the upstream of the proportional solenoid valve 92.1 and the outlet 92C while fully closing the connection between the downstream of the proportional solenoid valve 92.1 and the outlet 92B, under the effect of the aforementioned permanent overpressure which counteracts the effect of the spring integrated into the pressure compensator 92.2. When one of the actuators 41 of group G1 and one of the actuators 42 of group G2 are actuated simultaneously, the control unit 50 only partially opens the passage section of the proportional solenoid valve 92.1, with a proportion of opening corresponding substantially to the percentage that the target flow rate Q1 represents with respect to the sum of the target flow rates Q1 and Q2: in this case, the upstream of the proportional solenoid valve 92.1 presents an overpressure with respect to the downstream of this solenoid valve, so that the pressure compensator 92.2 partially opens the connection between the upstream of the solenoid valve and the outlet port 92C while closing, in an inverse proportion, the connection between the downstream of the solenoid valve and the outlet port 92B, until balancing between the pressure upstream of the proportional solenoid valve 92.1 and the pressure downstream of this solenoid valve, supplemented by the load of the spring integrated into the pressure compensator 92.2.

[0040] The flow control means 90 also comprise, for each of the actuators 41, an all-or-nothing distributor 93 which is adapted to send the fluid to the corresponding actuator 41, from the flow distribution device 92. At the inlet, each all-or-nothing distributor 93 is connected to the first outlet channel 92B of the flow distribution device 92, via the line 64, while the outlet of each all-or-nothing distributor 93 is connected to the reservoir 70, via a line 66 of the circulation circuit 60. Similarly, the flow control means 90 comprise, for each of the actuators 42, an all-or-nothing distributor 94 which is adapted to send the fluid to the corresponding actuator, from the flow distribution device 92.Each all-or-nothing distributor 94 is, at the input, connected to the second output channel 92C of the flow distribution device 92, via the line 65, while at the output, each all-or-nothing distributor 94 is connected to the reservoir 70 by the line 66 which is thus common to the different all-or-nothing distributors 93 and 94. The all-or-nothing distributors 93 and 94 are controlled by the control unit 50. Each all-or-nothing distributor 93, 94 is, for example, a four-way, three-position distributor.

[0041] The operation of the lifting platform 1 will now be described, thus illustrating an example of a method for controlling this lifting platform.

[0042] When the operator using the lifting platform 1 orders the actuation of one of the actuators 41 to move the part of the lifting structure 30, associated with this actuator 41, the target flow rate Q1 is determined as a function of this actuation, in particular of the speed of the latter. Similarly, when the operator orders the actuation of one of the actuators 42, the target flow rate Q2 is determined as a function of this actuation, in particular of the speed of the latter. In practice, the determination of the target flow rates Q1 and Q2 is carried out by the control unit 50, as explained above. Also as explained previously, the target flow rate Q1 is zero if none of the actuators 41 is actuated simultaneously with the actuator 42 concerned, or the target flow rate Q2 is zero if none of the actuators 42 is actuated simultaneously with the actuator 41 concerned.

[0043] In all cases, the motor pump 80 is then controlled, in practice by the control unit 50, so that the discharge flow rate QR of the fluid discharged by the motor pump is greater than or equal to the sum of the target flow rates Q1 and Q2. In particular, when the lifting structure 30 is moved at high speed, the sum of the target flow rates Q1 and Q2 is substantial and is therefore generally greater than the minimum value of the discharge flow rate QR, associated with the minimum speed at which the pump 81 must be driven by the motor 82 in the case where the motor pump 80 has the specific characteristic of exhibiting such a minimum drive speed.On the other hand, when the lifting structure 30 is moved at low speed, which is typically the case when the lifting structure is in a constrained environment and / or in approach phase, the sum of the target flows Q1 and Q2, in particular when one of these two target flows is zero, may be less than the minimum value of the discharge flow QR.

[0044] In all cases, a regulated proportion of the fluid discharged by the motor pump 80, with a controlled flow rate Q0 equal to the sum of the target flow rates Q1 and Q2, is sent jointly to groups G1 and G2 of the actuators 41 and 42. This regulation ensures that the flow sent to groups G1 and G2 maintains the controlled flow rate Q0, even when the discharge flow rate QR is greater than the value of the controlled flow rate Q0, by means of the corresponding excess discharge flow rate being discharged, the excess being returned directly to the reservoir 70. In practice, this regulation is carried out by the flow control device 91, which is controlled accordingly by the control unit 50, as detailed above.

[0045] The aforementioned regulated proportion is then divided into two adjusted parts, which respectively have the first target flow rate Q1 and the second target flow rate Q2 and which are respectively sent to the group G1 and to the group G2. This distribution ensures that the flow sent to each of the groups G1 and G2 corresponds to the fluid requirement for the actuation ordered by the operator. In particular, this distribution leads to the entirety of the aforementioned regulated proportion being sent only to the group G1 when the target flow rate Q2 is zero and, conversely, being sent only to the group G2 when the target flow rate Q1 is zero. In practice, this distribution is carried out by the flow distribution device 92, controlled accordingly by the control unit 50, as explained above.

[0046] The adjusted portion that is sent to group G1 then reaches actuator 41 whose actuation has been ordered by the user, via the all-or-nothing distributor 93 associated with this actuator 41, this all-or-nothing actuator 93 being controlled in the open position by the control unit 50 while the other all-or-nothing distributors 93 are kept closed. Similarly, the adjusted portion that is sent to group G2 reaches actuator 42 whose actuation has been ordered by the operator, via the all-or-nothing distributor 94 associated with this actuator 42, this all-or-nothing distributor 94 being controlled in the open position by the control unit 50 while the other all-or-nothing distributors 94 are kept closed.

[0047] Thus, the lifting structure 30 can be moved according to two simultaneous movements in a precise and controlled manner. The corresponding control of the lifting platform 1 is reliable, while being simple and inexpensive to implement. This being the case, it is understood that the hydraulic system S of the lifting platform 1 is not designed to move the lifting structure 30 according to more than two simultaneous movements. It is also understood that the hydraulic system S is not designed to move the lifting structure 30 according to two simultaneous movements which would result from two actuators 41 or which would result from two actuators 42, in other words according to two simultaneous movements which would result from two actuators of the same group among the groups G1 and G2. The size of the lifting platform 1 is therefore preferably adapted accordingly, the lifting platform 1 being in particular designed to raise the platform 20 to a height of less than 16 meters.Likewise, the lifting platform 1 is preferably “all electric”, that is to say that, in addition to the electric motor provided for its motor pump 80, the motor 14 of the lifting platform 1 is also electric: in particular, the chassis 10, which then advantageously integrates the motor pump 80, has a total electrical power which is preferably between 2 and 15 kW.

[0048] Finally, various modifications and variations to the lifting platform 1 and its control system, which have been described so far, can be considered. For example: within the lifting structure 30, the rotating turret 31 can be replaced by a fixed base; and / or in the case where the pump 81 of the motor pump 80 does not have the specificity of having to be driven at a predetermined minimum speed, the flow regulation device 91 can be simplified accordingly.

Claims

1. Aerial work platform (1) including: - a chassis (10) which is provided with ground translation members (11, 12), - a basket (20) which is adapted for an operator to stand on, - a lifting structure (30), which supports the basket and is arranged on the chassis so as to more or less lift the basket relative to the chassis, - hydraulic actuators (41, 42) which act on respective parts of the lifting structure so as to displace said respective parts relative to the rest of the lifting structure or relative to the chassis, - a hydraulic system (S) comprising: • a circulation circuit (60) through which fluid flows between a reservoir (70) and the hydraulic actuators, • a motor pump (80) which is electric and draws fluid from the reservoir and delivers to the circulation circuit for circulation, and • flow regulation means (90) for regulating fluid flow in the circulation circuit between the reservoir and the hydraulic actuators, and - a control unit (50) allowing to control the hydraulic system, wherein the hydraulic actuators (41, 42) are divided between a first group (G1) of one or more of the hydraulic actuators (41) and a second group (G2) of one or more of the hydraulic actuators (42), the hydraulic actuator or actuators of the first group being distinct from the hydraulic actuator or actuators of the second group, wherein the control unit (50) is able to: - determine both a first target flow rate (Q1) as a function of by-operator activation of the hydraulic actuator(s) (41) of the first group (G1) and a second target flow rate (Q2) as a function of by-operator activation of the hydraulic actuator(s) (42) of the second group (G2), and - control the motor pump (80) so that the motor pump delivers the fluid at a delivery flow rate (QR) which is greater than or equal to the sum of the first and second target flow rates (Q1, Q2), wherein the flow regulation means (90) are able, by being controlled by the control unit (50), to: - send jointly toward the first and second groups (G1, G2) a regulated proportion of fluid delivered by the motor pump (80), this regulated proportion presenting a controlled flow rate (Q0) which is equal to the sum of the first and second target flow rates (Q1, Q2), then - dividing said regulated proportion into two adjusted portions, which respectively present the first and second target flow rates and which are respectively sent to the first group and to the second group, wherein the flow regulation means (90) comprise a flow distribution device (92) which: - is provided with three ports, namely an inlet port (92A), which is supplied with said regulated proportion of the fluid delivered by the motor pump (80), a first outlet port (92B), which supplies fluid to the first group (G1), and a second outlet port (92C), which supplies fluid to the second group (G2), and - is able to distribute all fluid in the inlet port between the first and second outlet ports, the flow distribution device (92) being controlled by the control unit (50) so that the first outlet port receives the adjusted portion presenting the first target flow rate (Q1) and the second outlet port receives the adjusted portion presenting the second target flow rate (Q2), and wherein the flow regulation means (90) further comprise a flow regulating device (91), which: - is provided with three ports, namely an intake port (91A), which receives all fluid delivered by the motor pump (80), a main outlet port (91B), which sends fluid to the inlet port (92A) of the flow distribution device (92), and a secondary outlet port (91C), which sends fluid directly to the reservoir (70), and - is able to regulate a flow of fluid from the intake port toward the main and secondary outlet ports, the flow regulating device being controlled by the control unit (50) so that the main outlet port receives said regulated proportion of fluid delivered by the motor pump (80) while a surplus of fluid delivered by the motor pump, which has a flow rate equal to the difference between the delivered flow rate (QR) and the controlled flow rate (Q0), is evacuated through the secondary outlet port.

2. The aerial work platform according to claim 1, wherein the motor pump (80) includes a fixed-displacement pump (81) and an electric motor (82) which drives the fixed-displacement pump, the delivery flow rate (QR) being proportional to the speed at which the electric motor drives the fixed-displacement pump, wherein the fixed-displacement pump (81) is designed to be driven by the electric motor (82) at a predetermined minimum speed which is associated with a minimum value for the delivery flow rate (QR), the fixed-displacement pump being in particular a gear pump, and wherein the control unit (50) is unable to control driving of the fixed-displacement pump (81) below the predetermined minimum speed, irrespective of the values of the first and second target flow rates (Q1, Q2).

3. The aerial work platform according to any one of claims 1 or 2, wherein the flow distribution device (92) includes: - a first proportional electrovalve (92.1), which is able to control flow of fluid from the inlet port (92A) to the first outlet port (92B) so as to interrupt or adjust by a controlled passage section flow of fluid from the inlet port to the first outlet port, as a function of a control signal which the control unit (50) emits, from the respective values of the first and second target flow rates (Q1, Q2), and - a first pressure compensator (92.2), which is able to connect upstream of the first proportional electrovalve (92.1) to the second outlet port (92C) and to connect downstream of the first proportional electrovalve to the first outlet port (92B) according to inverse respective connection proportions which are a function of the pressure differential between upstream and downstream of the first proportional electrovalve.

4. The aerial work platform according to any one of the preceding claims, wherein the flow regulating device (91) includes: - a second proportional electrovalve (91.1), which is able to control flow of fluid from the intake port (91A) to the main outlet port (91B) so as to interrupt or adjust by a controlled passage section flow of fluid from the intake port to the main outlet port, as a function of a control signal which the control unit (50) emits, from the sum of the first and second target flow rates (Q1, Q2), and - a second pressure compensator (91.2), which is able to connect upstream of the second proportional electrovalve (91.1) to the secondary outlet port (91C) according to a connection proportion which is a function of the pressure differential between upstream and downstream of the second proportional electrovalve.

5. The aerial work platform according to claim 4, wherein the flow regulating device (91) also includes an on-off electrovalve (91.3), which is able to control communication between a spring loaded chamber of the second pressure compensator (91.2) and the reservoir (70) so as to interrupt or allow communication between the spring loaded chamber of the second pressure compensator, as a function of a control signal which the control unit (50) emits.

6. The aerial work platform according to one of claims 4 or 5, wherein the chassis (10) is equipped with a hydraulic steering device (13), which acts on at least some of the ground translation members (11, 12) so as to adjust orientation of the at least some of the ground translation members relative to the chassis in order to direct the aerial work platform (1) on the ground, and wherein the flow regulating device (91) further includes an on-off distributor (91.4) which is controlled by the control unit (50) and able to send fluid from downstream of the second proportional electrovalve (91.1) toward the hydraulic steering device (13).

7. The aerial work platform according to any one of the preceding claims, wherein the flow regulating device (91) is integrated into the chassis (10).

8. The aerial work platform according to any one of the preceding claims, wherein several hydraulic actuators (41, 42) are provided in the first group (G1) and / or in the second group (G2) and are each associated with an on-off distributor (93, 94) of the flow regulation means (90), which is controlled by the control unit (50) and is able to send fluid to the corresponding hydraulic actuator from the rest of the flow regulation means.

9. The aerial work platform according to any one of the preceding claims, wherein the lifting structure (30) comprises a turret (31), which rests on the chassis (10) and is rotatable relative to the chassis about an rotation axis extending perpendicularly to the ground, and an arm (32), which connects the turret to the basket (20) and is deployable to move the basket more or less away from the turret, and wherein the hydraulic actuators (41, 42) act both on the turret (31) to rotate the turret about the rotation axis relative to the chassis (10) and on the arm (32) to deploy the arm relative to the turret.

10. The aerial work platform according to any one of the preceding claims, wherein the lifting structure (30) is designed to lift the basket (20) to a height of less than 16 meters.

11. The aerial work platform according to any one of the preceding claims, wherein the chassis (10) incorporates the motor pump (80) and an electric motor (14) which drives the ground translation members (11, 12), the chassis having a total electric power of between 2 and 15 kW.

12. A method for controlling an aerial work platform (1), the aerial work platform comprising: - a chassis (10) provided with ground translation members (11, 12), - a basket (20) suitable for an operator to stand on, - a lifting structure (30), which supports the basket and is arranged on the chassis so as to more or less lift the basket relative to the chassis, - hydraulic actuators (41, 42), which act on respective parts of the lifting structure so as to move said respective parts relative to the rest of the lifting structure or relative to the chassis, and which are divided between a first group (G1) of one or more of the hydraulic actuators (41) and a second group (G2) of one or more of the hydraulic actuators (42), the hydraulic actuator or actuators of the first group being distinct from the hydraulic actuator or actuators of the second group, and - a hydraulic system (S) comprising: • a circulation circuit (60) through which fluid flows between a reservoir (70) and the hydraulic actuators, • a motor pump (80) which is electric and draws fluid from the reservoir and delivers to the circulation circuit for circulation, and • flow regulation means (90) for regulating fluid flow in the circulation circuit between the reservoir and the hydraulic actuators, wherein a first target flow rate (Q1) is determined as a function of activation of one or more hydraulic actuators (41) of the first group (G1) by an operator using the aerial work platform (1), wherein a second target flow rate (Q2) is determined as a function of activation of one or more hydraulic actuators of the second group (G2) by the operator, wherein the motor pump (80) is controlled so that fluid delivered by the motor pump presents a delivery flow rate (QR) which is greater than or equal to the sum of the first and second target flow rates (Q1, Q2), wherein the flow regulation means (90) are controlled to: - jointly send toward the first and second groups (G1, G2) a regulated proportion of fluid delivered by the motor pump (80), the regulated proportion presenting a controlled flow rate (Q0) which is equal to the sum of the first and second target flow rates (Q1, Q2), then - divide said regulated proportion into two adjusted portions, which respectively present the first and second target flow rates (Q1, Q2) and which are respectively sent to the first group (G1) and to the second group (G2), wherein the flow regulation means (90) comprise: - a flow distribution device (92) which is provided with three ports, namely an inlet port (92A), which is supplied with said regulated proportion of fluid delivered by the motor pump (80), a first outlet port (92B), which sends fluid to the first group (G1), and a second outlet port (92C), which sends fluid to the second group (G2), and - a flow regulating device (91) which is provided with three ports, namely an intake port (91A), which receives all fluid delivered by the motor pump (80), a main outlet port (91B), which sends fluid to the inlet port (92A) of the distribution device (92), and a secondary outlet port (91C), which sends fluid directly to the reservoir (70), wherein the flow distribution device (92) is controlled to distribute all fluid in the inlet port between the first and second outlet ports, so that the first outlet port receives the adjusted portion presenting the first target flow rate (Q1) and the second outlet port receives the adjusted portion presenting the second target flow rate (Q2), and wherein the flow regulating device (91) is controlled to regulate the flow of fluid from the intake port to the main and secondary outlet ports, so that the main outlet port receives said regulated proportion of fluid delivered by the motor pump (80) while an excess of fluid delivered by the motor pump, which has a flow rate equal to the difference between the delivered flow rate (QR) and the controlled flow rate (Q0), is evacuated through the secondary outlet port.