Manually operated hydraulic lowering device for lifting equipment

Abstract

Hydraulic lowering device for a safety brake of a lifting device, comprising a fluid reservoir (1), a fluid outlet (18), a pressurized fluid accumulator (2), a pump (3) connected to the reservoir for injecting the fluid from the reservoir under pressure into the accumulator, a three-way pressure regulator (4) having a mechanical control input, actuated via a handwheel (5), for setting a setpoint value, a fluid inlet connected to the accumulator (2), a fluid outlet connected to the fluid outlet (18), and a drain connected to the reservoir (1). The three-way pressure regulator allows the release, reinforcement and weakening of the brake to be controlled precisely and safely. The separation between the creation, by pumping, of an energy reserve in the accumulator and the control of the lowering via the pressure regulator facilitates control. Figure for abstract: Fig. 1

Description

Title of the invention: Manually controlled hydraulic lowering device for lifting equipment Technical field

[0001] The present application relates to a manually controlled hydraulic lowering device for lifting equipment. State of the art

[0002] A lifting device of the crane, overhead crane, etc. type, usually comprises a line provided with a drum around which suspension cables are wound to which the load to be lifted is attached. Such a lifting device can be used to lift extremely heavy loads, for example weighing more than 50 tonnes, and the weight of which is sometimes not the only source of danger (the load may for example be a radioactive material or a bucket filled with molten metal).

[0003] The lifting machine needs to be equipped with brakes for several functions, including: slowing down and then stopping the load when approaching a stop position (service brake); blocking the lifting machine when it is in its stop position, i.e. when the load is at the desired height (parking brake); stopping and blocking the lifting machine in the event of an electrical failure or, more generally, in the event of an emergency of any nature (safety brake, also called an emergency brake or "failsafe brake" in English).

[0004] A safety brake is configured to be triggered when it is no longer supplied with electricity (in the event of a power failure): this is called a lack brake or negative brake. Disc brakes have been used for this purpose since the 1960s, in particular because their heating poses little or no problems.

[0005] A safety disc brake generally comprises:

[0006] - a disc secured to the line to be braked,

[0007] - a clamp, comprising two plates capable of clamping the disc, which chainrings are usually fitted with friction pads,

[0008] - for each tray or for one of the two trays only, a spring with washers configured to impose a pressure force on said plate in the direction of closing the brake, that is to say so as to push and maintain under pressure the plates against the disc and thus tighten the clamp,

[0009] - an actuator, which can be electrohydraulic or electromagnetic or electromechanical, and which presses against one end of the washer spring so as to compress it in the direction of opening the brake; when the actuator is under tension, it compresses the washer spring, which opens the clamp and releases the disk (and therefore the line) rotating.

[0010] In the event of an electrical failure, the actuator suddenly becomes inoperative, releasing the washer spring which closes the brake. The load is then stopped and remains suspended in the air.

[0011] The load must then be lowered again, even though the electricity may still not be restored. This operation is carried out using a hydraulic lowering device, which allows the safety brake to be slightly reopened and thus allows the line to rotate and the load to be lowered.

[0012] The electromagnetic and electromechanical safety brakes are thus equipped with a hydraulic release chamber and a “hydraulic release” connection to which an operator can connect a hydraulic lowering unit when a lowering operation is necessary.

[0013] Being by definition managed by a hydraulic system, already integrated into the brake or not, hydraulic brakes are for their part comprised of a main hydraulic chamber for the current management of the brake, and they are generally provided with a “lowering option” which allows control of the hydraulic management system of the brake to be taken.

[0014] In all cases, the brake comprises a hydraulic chamber into which a fluid (for example oil) under pressure can be injected, which hydraulic chamber bears against one end of the washer spring of the brake so as to compress said spring in the direction of opening of the brake. Throughout the following, this hydraulic chamber is called the hydraulic brake release chamber, including when it is an electrohydraulic brake and the chamber in question is not only a release chamber but is also the main operating chamber of the brake.

[0015] In known brakes (whatever the nature of the brake), the lowering must be managed by an operator from the lifting bridge or the top of the crane, in an uncomfortable and dangerous position because at height.

[0016] In known brakes (whatever the nature of the brake), the hydraulic release device integrated into the brake or which is connected to it when a lowering operation is necessary is equipped with a fluid reservoir, a lever-operated hand pump which will supply a volume of fluid following an action on its lever, and a flow limiter which will maintain a permanent controlled leak to the reservoir.

[0017] The combination of the pump flow and the leakage flow generates a counter-pressure in the hydraulic chamber of the brake, opposing the force of the washer spring via the hydraulic release device.

[0018] When the counter pressure produces a force just greater than the pinching force sufficient to hold the load, sliding begins and the load descends.

[0019] Although functional on paper, in practice, the adjustment of the pressure in the hydraulic chamber is only accessible by matching the pumping frequency to the leakage flow rate.

[0020] In order to balance the volume of fluid injected into the hydraulic brake release chamber, the operator must adjust the pumping force and speed throughout the entire duration of the lowering, both of which vary depending on the expected pressure, which causes stress, fatigue and risk.

[0021] Thus, the known lowering devices are very difficult to operate and they do not allow the load to be lowered in a slow and controlled manner. Indeed, they do not allow the operator to "feel" the pressure in the hydraulic chamber of the brake, nor to easily regulate this pressure. In practice, the lowering device may ultimately react in an all-or-nothing manner: while the brake is still applied, a single additional action on the pump lever can cause a rapid and significant increase in the pressure in the hydraulic release chamber, which results in the opening of the brake and the subsequent dropping of the load.

[0022] Furthermore, not only is the device devoid of means for controlling the pressure in the hydraulic release chamber, but in addition, once the equilibrium pressure is exceeded, the lowering device does not allow the operator to act to reduce in a controlled manner the quantity and / or the pressure of fluid in the hydraulic chamber in order to slightly close the brake so as to slow the fall of the load.

[0023] Note that the term "balance pressure" of the brake means the fluid pressure in the hydraulic release chamber which allows the washer spring to be compressed (in the direction of opening the brake) but without detaching the pads from the disc, in other words the fluid pressure which allows the hydraulic chamber to exactly counter the force exerted by the spring on the clamp plates to retain the load. When this balance pressure is reached in the hydraulic chamber, the load is no longer retained by the brake although it is not really open.

[0024] In order for the load to be lowered in a slow, progressive and controlled manner, the pressure in the chamber must be both greater than this equilibrium pressure so that the brake plates do not exert a force likely to block the disc, and sufficiently close to this pressure so that the plates press sufficiently on the disc to slow down the descent of the load. Statement of the invention

[0025] The invention aims to overcome at least one of the aforementioned drawbacks by proposing a lowering device for lifting equipment, which allows a load to be lowered from in a safe, controlled manner that is easy to operate and safe for the operator.

[0026] To this end, the invention proposes a hydraulic lowering device for a safety brake of a lifting machine, intended to be used with a brake provided with a hydraulic release chamber and a fluid inlet connection, called a release connection, the lowering device comprising a fluid reservoir and a fluid outlet. The lowering device according to the invention is characterized in that it comprises: - a pressurized fluid accumulator, connected to the fluid reservoir, - a pump connected to the tank to inject fluid present in the tank under pressure into the accumulator, - a three-way pressure regulator comprising a mechanical control input for adjusting a setpoint value, a fluid inlet connected to the accumulator, a first fluid outlet connected to the fluid outlet socket of the lowering device, and a second fluid outlet, called drain, connected to the reservoir, - a manual actuation device for the pressure regulator control input, - an extension for the fluid connection from the fluid outlet socket to the safety brake release connection. The lowering device according to the invention is used as follows:

[0027] - when a lowering operation is necessary, an operator comes to connect the lowering device on the safety brake release connection, via the lowering device extension,

[0028] - initially, the operator focuses on creating a reserve energy; it operates the pump to pressurize the fluid in the accumulator until a pressure in the accumulator is obtained corresponding, for example, to the maximum pressure permitted in the hydraulic chamber of the brake or preferably corresponding to the maximum admissible pressure in the accumulator,

[0029] - in a second step, the operator concentrates on the piloting itself; it changes the pressure in the hydraulic chamber of the brake as it wishes by manipulating the manual actuation member of the control input of the three-way pressure regulator, in order to control the descent of the load.

[0030] Thus, the invention is based on the combination of two principles:

[0031] - the decoupling between the pressurization of the fluid intended to be injected into the hydraulic brake release chamber, and the injection of this fluid into said chamber, that is to say the decoupling between the physical pumping action (which requires power) and the pressure adjustment action (which requires finesse, precision, and attention), this decoupling being made possible by the provision of an ac- accumulator in the lowering device;

[0032] - control of the pressure in the hydraulic chamber of the brake, thanks to the provision of a three-way pressure regulator between this accumulator and the fluid outlet of the lowering device; lowering is therefore carried out by regulating a pressure and not a volume or a flow rate as is the case with known lowering devices.

[0033] In addition, the use of a three-way pressure regulator makes it possible to control the pressure in the hydraulic brake release chamber in both directions:

[0034] - if the setpoint value requested at the regulator control input is su higher than the regulator outlet pressure, i.e. the fluid pressure in the hydraulic brake release chamber, the pressure regulator connects the fluid inlet and the fluid outlet of the regulator, i.e. respectively the accumulator and the brake release circuit; the fluid flows towards the brake and the pressure in the hydraulic release chamber increases, which weakens the brake;

[0035] - if the set value is lower than the fluid pressure in the hy chamber brake release hydraulics, the regulator connects the regulator's fluid outlet and the drain, i.e. the brake and the reservoir respectively; the fluid flows towards the reservoir from the hydraulic release chamber, which reinforces the brake,

[0036] - if the set value is equal to the pressure of the fluid in the chamber hy brake release hydraulics, the pressure regulator closes the three channels, this corresponds to a stable lowering phase where the braking force is slightly lower than the force due to the load.

[0037] Furthermore, once the extension is connected to the brake, the lowering device can be used from the ground, the operator being able to settle into a stable and comfortable posture, which is not insignificant given the fact that a lowering operation can take several hours depending on the load concerned.

[0038] Furthermore, the device according to the invention has the advantage of being compatible with the vast majority of known safety brakes, in particular with all safety brakes with hydraulic actuator and with all electromagnetic or electromechanical safety brakes equipped with a hydraulic release option.

[0039] According to particular embodiments of the invention, the lowering device further meets the following characteristics, implemented individually or in any technically possible and operational combination.

[0040] In some embodiments, the lowering device comprises a safety stop device, called a dead man's safety device, comprising a safety handle configured to be able to be moved by an operator between a passive locking position which prohibits the injection of fluid into the hydraulic chamber of brake release and an active unlocking position which allows the injection of fluid into the hydraulic brake release chamber, the safety lever being automatically returned to its passive locking position in the absence of action from the operator.

[0041] The dead man's safety device guarantees completely safe lowering. At any time, the load can be instantly stopped by releasing the safety lever.

[0042] In certain embodiments, the lowering device further comprises: - a first pressure sensor for measuring the pressure of the fluid at the inlet of the three-way pressure regulator and a first display means associated with said first sensor for displaying the measured pressure, - a second pressure sensor for measuring the fluid pressure at the fluid outlet of the lowering device or at the outlet of the pressure regulator, and a second display means associated with said second sensor for displaying the measured pressure.

[0043] The first pressure sensor and the first associated display means (to said first sensor) are for example a first pressure gauge capable of measuring pressures up to 250 bar, and the second pressure sensor and the second display means (associated with said second sensor) are for example a second pressure gauge capable of measuring pressures up to 150 bar.

[0044] These pressure sensors and associated display means make it possible to know and control on the one hand the pressure available in the accumulator, which corresponds to the pressure at the inlet of the pressure regulator, and on the other hand the pressure prevailing in the hydraulic brake release chamber, which corresponds to the pressure of the fluid at the fluid outlet of the device and which also preferably corresponds to the pressure at the outlet of the pressure regulator. The usefulness of these pressure sensors and associated display means will be better understood on reading the detailed description below.

[0045] In certain embodiments, the lowering device comprises, in parallel with the pressure regulator, a fluid return circuit between the fluid outlet and the reservoir, allowing the brake release chamber to be emptied into the reservoir. As will be understood later, this return circuit also contributes to the safety of the lowering device and the brake, in combination, respectively, with the dead man's safety device and with a pressure limiter (described later).

[0046] In some embodiments, the lowering device comprises a mobile carriage on which all the components of the device are mounted. This mobile carriage contributes to the ergonomics of the device according to the invention, in that it allows the operator to easily install himself at the most appropriate location to control the lowering.

[0047] In some embodiments, the pump may be: a hand pump, for example a piston pump manually activated by a lever; a motorized pump, for example a rotary gear pump associated with a screwdriver, the pump comprising a gear provided with a recess for receiving a screwdriver bit for driving said gear in rotation by said screwdriver. The screwdriver is provided with a battery so that it can be supplied with electricity under any circumstances (in particular in the event of a power failure).

[0048] The device may comprise several pumps each connected to the reservoir, including, for example, a hand pump and a motorized pump.

[0049] In some embodiments, the lowering device comprises: - a main drilled block to which the tank, the pump, and a pressurizing hose connecting the accumulator to said main drilled block are connected, and - a secondary drilled block to which the pressure regulator is connected, a supply hose connected to the accumulator via the main drilled block, a return hose connected to the tank via the main drilled block, and the fluid outlet of the lowering device, as well as the first and second pressure sensors when present.

[0050] In some embodiments, the lowering device includes a pressure limiter between the accumulator and the reservoir, configured to limit the fluid pressure injected into the accumulator.

[0051] In some embodiments, the return circuit (between the fluid outlet and the reservoir) includes another pressure limiter configured to limit the fluid pressure that is injected via the fluid outlet into the hydraulic brake release chamber.

[0052] In some embodiments, wherein the dead man's device comprises: - a first solenoid valve on the return circuit, which first solenoid valve is configured to be open when the safety handle is in the passive locking position and to be closed when the safety handle is in the active unlocking position, and - a second solenoid valve at the inlet of the pressure regulator, which second solenoid valve is configured to be closed when the safety handle is in the passive locking position and to be open when the safety handle is in the active unlocking position.

[0053] The invention extends to a method of lowering a load onto a lifting machine, characterized in that it uses a lowering device as previously defined, and in that it comprises: - a step of pressurizing the accumulator during which at least part of the fluid present in the reservoir is injected into the accumulator by activation of the pump; - a step of controlling the pressure at the pressure regulator outlet using the manual actuation member of the pressure regulator control input so as to control the lowering of a load carried by the lifting equipment, - the pressurization and piloting steps being carried out successively, independently of each other.

[0054] Preferably, the accumulator is pressurized until the maximum pressure that the accumulator can withstand is obtained in the accumulator. During lowering, if necessary, that is to say if the pressure at the inlet of the pressure regulator becomes insufficient, the operator can stop the lowering of the load by imposing a set value on the regulator that is low enough for the brake to be applied, stop his control to pressurize the accumulator again using the pump, then finally resume his control once the accumulator has thus been "reinflated". Preferably, the operator reinflates the accumulator until the maximum value admissible by the accumulator is obtained at the inlet of the regulator, in order to avoid having to reinflate the accumulator frequently. Brief description of the drawings

[0055] The invention, according to an exemplary embodiment, will be well understood and its advantages will appear better on reading the detailed description which follows, given for information purposes and in no way limiting, with reference to the appended drawings in which:

[0056] [Fig-1] [Fig. 1] is a perspective view of a first exemplary embodiment of a hydraulic lowering device according to the invention;

[0057] [Fig.2] [Fig.2] represents the example of embodiment of [Fig.l], seen in perspective from an opposing point of view;

[0058] [Fig.3] [Fig.3] is a perspective view of part of a second example of production of a hydraulic lowering device according to the invention;

[0059] [Fig.4] [Fig.4] is an exploded perspective view of a third example of a sheave use of a device according to the invention;

[0060] [Fig.5] [Fig.5] is a hydraulic diagram of the embodiment example of [Fig.4]. Detailed description

[0061] Identical elements shown in the above-mentioned figures are identified by identical numerical references.

[0062] [Fig. 1] and 2 represent a first exemplary embodiment of a lowering device according to the invention. Reference is also made to Figures 4 and 5 for the common parts between this first exemplary embodiment and the third exemplary embodiment which is represented in these [Fig. 4] and 5.

[0063] The lowering device according to the invention of [Fig.l] and 2 comprises:

[0064] - a reservoir 1 containing a fluid such as oil,

[0065] - an accumulator 2 capable of withstanding a pressure of 200 bar for example,

[0066] - a piston pump 3 which can be manually operated by a lever 10,

[0067] - a main drilled block 13 and a secondary drilled block 14 which facilitate the connection hydraulics of some of the elements of the lowering device between them (see further),

[0068] - a three-way pressure regulator (see [Fig.4] and 5), more simply also called pressure regulator - or even regulator - throughout the description,

[0069] - a handwheel 5 for controlling the pressure at the outlet of the pressure regulator, which corresponds to the pressure of the hydraulic chamber of the brake, the axis 6 of said handwheel (see [Fig.4]) being fitted into the control input of the pressure regulator.

[0070] - a dead man safety device comprising in particular a lever of security 7,

[0071] -a collar pressure gauge 8 for measuring and displaying the pressure at the inlet of the pressure regulator 4,

[0072] - a collar pressure gauge 9 for measuring and displaying the pressure at the outlet of the regulator 4,

[0073] - a fluid outlet socket 18 to which the operator connects the end of a pipe (not shown), referred to as an extension, the opposite end of said extension being connected to a fluid inlet connection of the safety brake,

[0074] - a fluid return circuit 30 (see [Fig.5]) which connects the fluid outlet socket 18 to tank 1.

[0075] The second embodiment illustrated in [Fig.3] differs from the first example in that its pump is a motorized submersible pump 3' (see [Fig.4]) comprising a gear driven by a screwdriver 11.

[0076] The third example illustrated in [Fig.4] differs from the two previous examples in that it comprises two pumps, including a submersible pump 3' driven by a screwdriver 11, similar to the pump of the second example, and a hand pump 3 actuated by a lever 10, similar to that of the first embodiment.

[0077] Reference is now made to the hydraulic diagram of [Fig.5] which is valid for the three proposed embodiment examples, with the exception of the presence of two pumps which only concerns the third example.

[0078] The sets delimited by dotted lines represent respectively the reservoir 1, the main drilled block 13 and the secondary drilled block 14.

[0079] The pumps 3 and 3' are connected on the one hand to the reservoir 1 and on the other hand to the main drilled block 13; they allow the fluid present in the reservoir 1 to be injected into the accumulator 2 via the main drilled block 13, to which the accumulator 2 is connected by a first hose 15, called the pressurizing hose, and via non-return valves 20 (for the hand pump 3) and 21 (for the gear pump 3').

[0080] A pressure limiter 22, also mounted on the main drilled block 13, prevents the accumulator from inflating beyond its maximum admissible pressure by returning the pumped fluid to the reservoir 1 when this pressure is reached.

[0081] Furthermore, in the usual manner, the tank 1 is equipped with a level detector 12.

[0082] A second flexible hose 16, called a supply flexible hose, extending between the drilled block main 13 and the secondary drilled block 14 make it possible to connect the accumulator 2 to the fluid inlet of the pressure regulator 4.

[0083] The collar pressure gauge 8 measures and displays the pressure PI, which corresponds both to the fluid pressure in the accumulator 2 and to the fluid pressure at the inlet of the pressure regulator 4. The collar pressure gauge 9 measures and displays the pressure P2, which corresponds both to the pressure at the outlet of the pressure regulator 4, to the pressure at the fluid outlet 18 of the lowering device and to the pressure in the hydraulic brake release chamber.

[0084] When the operator increases, using the handwheel 5, the set pressure at the control input of the pressure regulator, the pressure P2 at the output of the regulator increases accordingly and the fluid is injected into the hydraulic brake release chamber via the extension.

[0085] When the operator operates the handwheel 5 so as to reduce the set pressure, the outlet pressure P2 decreases and the fluid flows in the other direction, from the brake to the lowering device. The fluid is then returned to the reservoir 1 via the return circuit 30, and in particular via a conduit 26, arranged in the secondary drilled block 14, then via a third hose 17, called the return hose, extending between the secondary drilled block 14 and the main drilled block 13.

[0086] Optionally but advantageously, a pressure limiter 27 is provided on the return pipe 26 in order to secure the brake. If, through clumsiness or error, the operator imposes, at the control input of the pressure regulator 4, a pressure setpoint which exceeds the pressure supported by the hydraulic brake release chamber, the pressure limiter 27 opens and part of the fluid is directed towards the reservoir instead of being sent into the brake.

[0087] The presence of this pressure limiter 27 makes it possible to use the lowering device without risk for any type of brake, not only for brakes whose hydraulic release chamber can withstand up to 180 bar (such as a safety brake intended for a lifting machine capable of carrying several tens, or even hundreds, of tons), but also for lower-power brakes whose hydraulic release chamber is limited to 20 bar for example. In the absence of such a pressure limiter 27, one way of reducing the risks of damage to the brake is to limit the pressure PI to which the accumulator is previously inflated, by stopping the step of pressurizing the accumulator when the pressure PI approaches the pressure maximum supported by the hydraulic brake release chamber (which is a known technical specification of the brake).

[0088] The dead man device comprises a safety solenoid valve 25 on the fluid return circuit 30. The solenoid valve 25 is actuated by a progressive stop 24 (see [Fig.4]) pressed by the safety lever 7. When the operator presses the safety lever 7, the safety solenoid valve 25 is closed and the pressure at the outlet of the regulator 4 is sent into the brake, or possibly into the return conduit 26 in the event of exceeding the maximum pressure supported by the brake.

[0089] Releasing the safety lever 7 causes the progressive stop 24 to return, the solenoid valve 25 to open and the circuit to be emptied into the reservoir 1 at the outlet of the pressure regulator (including the hydraulic brake release chamber), which causes the brake to close immediately.

[0090] In addition to the solenoid valve 25, a second solenoid valve 23 may be provided in the secondary drilled block 14 at the inlet of the pressure regulator 4. This second solenoid valve 23 is actuated, in the closing direction, by a second progressive stop 24 which is depressed when the operator presses the safety lever 7.

[0091] Releasing the safety lever 7 therefore causes in this case, not only the opening of the solenoid valve 25, but also the closing of the solenoid valve 23, which has the consequence of isolating the accumulator 2 from the rest of the circuit. The solenoid valve 23 is optional, it comes in addition to the solenoid valve 25 to guarantee very rapid closing of the brake, avoiding emptying and filling at the same time the hydraulic brake release chamber. The solenoid valve 23 thus makes it possible to gain in brake release time.

[0092] The dead man safety device illustrated (with its lever 7, its two solenoid valves and its two progressive stops) is of course described only as a non-limiting example. A person skilled in the art is able to design, in general, a dead man safety device using his general knowledge. For example, as a variant, it would be possible to provide a controlled safety device originating from a customer detection such as overspeed, overheating, clock, etc. This variant is less interesting in that it requires the device to be equipped with a battery to electrically power the detection means in the event of a power failure.

[0093] In the example illustrated in [Fig.5], a flow limiter 37 is also provided between the accumulator and the tank. This limiter is used in ON / OFF like a tap, in order to allow the emptying (in the ON position) of the accumulator 2 towards the tank 1 to put the lowering device into rest.

[0094] In the context of the lowering method according to the invention, the operator first builds up an energy reserve by inflating the accumulator to the maximum using pump 3 or pump 3'. He can repeat this operation as many times as necessary. necessary during lowering, taking care first to block the load by reducing the set value at the control input of the pressure regulator.

[0095] He then operates the handwheel 5 so as to increase the pressure in the brake, more or less quickly, until the load is released. This means that he has exceeded the equilibrium pressure in the brake. This equilibrium pressure depends not only on the brake but also and above all on the load (this is not a technical specification of the brake alone); it is therefore unknown to the operator at the start of lowering.

[0096] The pressure gauge 9 allows the operator to know the value of this equilibrium pressure at the moment when the load begins to descend suddenly. He then suddenly operates the steering wheel in the other direction to close the brake and stop the load. Now that he knows approximately the equilibrium pressure, the operator can handle the steering wheel more precisely so as to quickly return to near this pressure and then gradually exceed it to slide the load. He then easily controls the speed of lowering of the load by precisely controlling the pressure regulator 4 around the equilibrium pressure.

[0097] That being said, a lowering device without a pressure gauge 9 is in accordance with the invention. The operator must then control the regulator blindly, without ever knowing the value of the equilibrium pressure. Without being essential, the pressure gauge 9 helps to reduce the stress of the operator.

[0098] The pressure gauge 8 allows the operator to know the state of the energy reserve available to him in the accumulator 2. This allows him to anticipate a possible lack of pressure and the need to reinflate the accumulator. The pressure gauge 8 is an optional element of the lowering device according to the invention, this element not being essential to the safety of the operator or to the success of the lowering (a lack of pressure at the regulator input resulting in the brake closing and the load stopping). Just like the pressure gauge 9, the pressure gauge 8 contributes to the ergonomics of the lowering device and helps to reduce the stress of the operator.

[0099] In addition to the pressure gauges 8 and 9, the lowering device illustrated in [Fig.5] comprises two other pressure taps, namely: - a pressure sensor 28 at the main drilled block 13 configured to measure the pressure PI; this sensor 28 theoretically indicates the same measurement as the pressure gauge 8, i.e. the pressure PI delivered by the accumulator, - a pressure sensor 29 on the return circuit between the fluid outlet 18 and the pressure limiter 27; this sensor 29 theoretically indicates the same pressure as the pressure gauge 9, i.e. the pressure delivered by the pressure regulator 4 which also corresponds to the pressure in the hydraulic brake release chamber.

[0100] These additional sensors can be connected to a recording device or to a remote control device, for retrospective or remote analysis of the lowering operation.

[0101] The lowering device according to the invention finally preferably comprises a rolling carriage 31 which, in the examples illustrated, comprises, among other things, wheels 35, two sides 32, 33 connected in particular by a lower plate 36 and by an upper plate 34 on which the collar pressure gauges 8 and 9 and the safety lever 7 are mounted.

Claims

Claims

1. Hydraulic lowering device for a safety brake of a lifting machine, intended to be used with a brake provided with a hydraulic release chamber and a fluid inlet connection, called the release connection, the lowering device comprising: - a fluid reservoir (1), and - a fluid outlet socket (18), characterized in that it comprises: - a pressurized fluid accumulator (2), connected to the fluid reservoir (1), - a pump (3, 3') connected to the reservoir for injecting fluid present in the reservoir under pressure into the accumulator, - a three-way pressure regulator (4) comprising a mechanical control input for adjusting a set value, a fluid inlet connected to the accumulator (2), a first fluid outlet connected to the fluid outlet socket (18) of the lowering device, and a second fluid outlet, called a drain, connected to the reservoir (1),- a member (5) for manual actuation by an operator of the mechanical control input of the pressure regulator (4), - an extension for the fluid connection of the fluid outlet socket (18) to the safety brake release connection.,

2. Lowering device according to claim 1, comprising a safety stop device, called a dead man's safety device, comprising a safety lever (7) configured to be able to be moved by an operator between a passive locking position which prohibits the injection of fluid into the hydraulic brake release chamber and an active unlocking position which authorizes the injection of fluid into the hydraulic brake release chamber, the safety lever (7) being automatically returned to its passive locking position in the absence of action by the operator.

3. A lowering device according to one of claims 1 or 2, comprising: - a first pressure sensor (8) for measuring the pressure of the fluid at the inlet of the pressure regulator (4) and a first display means (8) associated with said first sensor for displaying the measured pressure, - a second pressure sensor (9) for measuring the pressure of the fluid at the fluid outlet of the lowering device or at the outlet of the lowering device, output of the pressure regulator and a second display means (9) associated with said second sensor for displaying the measured pressure.

4. A lowering device according to claim 3, wherein the first pressure sensor and the first display means are a first pressure gauge (8) capable of measuring pressures up to 250 bar, and the second pressure sensor and the second display means are a second pressure gauge (9) capable of measuring pressures up to 150 bar.

5. A lowering device according to one of claims 1 to 4, comprising a fluid return circuit (30) between the fluid outlet (18) and the reservoir (1) in parallel with the pressure regulator (4).

6. A lowering device according to one of claims 1 to 5, comprising a movable carriage (31) on which all the components of the lowering device are mounted.

7. Lowering device according to one of claims 1 to 6, the pump is chosen from: a piston pump (3) manually activated by a lever (10), a rotary gear pump (3') associated with a screwdriver (H).

8. A lowering device according to one of claims 1 to 7, comprising: - a main drilled block (13) to which the reservoir (1), the pump (3) and a pressurizing hose (15) connecting the accumulator (2) to said main drilled block are connected, and - a secondary drilled block (14) to which the pressure regulator (4) are connected, a supply hose (16) connected to the accumulator via the main drilled block (13), a return hose (17) connected to the reservoir (1) via the main drilled block (13), and the fluid outlet (18) of the lowering device.

9. A lowering device according to one of claims 1 to 8, comprising a pressure limiter (22) between the accumulator (2) and the reservoir (1), configured to limit the fluid pressure injected into the accumulator.

10. A lowering device according to claim 5, wherein the return circuit (30) comprises a further pressure limiter (27) configured to limit the fluid pressure injected into the hydraulic brake release chamber via the fluid outlet (18).

11. A lowering device according to one of claims 1 to 10, wherein the dead man's device comprises: - a first solenoid valve (25) on the return circuit (30), which first solenoid valve is configured to be open when the safety lever (7) is in the passive locking position and to be closed when the safety lever is in the active unlock position, and - a second solenoid valve (23) at the inlet of the pressure regulator (4), which second solenoid valve is configured to be closed when the safety lever (7) is in the passive locking position and to be open when the safety lever is in the active unlocking position.

12. Method for lowering a load onto a lifting device, characterized in that it uses a lowering device according to one of the preceding claims, and in that it comprises: - a step of pressurizing the accumulator (2) during which at least part of the fluid present in the reservoir (1) is injected into the accumulator (2) by activating the pump (3, 3'), - a step of controlling the pressure at the outlet of the pressure regulator (4) using the member (5) for manually actuating the control input of the pressure regulator so as to control the lowering of a load carried by the lifting device, - the pressurization and piloting steps being carried out successively, independently of each other.

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