Manually operated hydraulic lowering device for lifting equipment

Abstract

Hydraulic lowering device for the safety brake of a lifting machine, comprising a fluid reservoir (1), a fluid outlet (18), a pressurized fluid accumulator (2), a pump (3) connected to the reservoir for injecting pressurized fluid from the reservoir 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 for precise and safe control of the brake release, reinforcement, and weakening. Separating the pumping of an energy reserve in the accumulator from the lowering control via the pressure regulator simplifies operation. Figure for the abstract: Fig. 1

Description

Title of the invention: Manually operated hydraulic lowering device for lifting equipment technical field

[0001] This application relates to a manually operated hydraulic lowering device for lifting equipment. State of the art

[0002] A lifting device such as a crane, overhead crane, etc., usually comprises a line equipped 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 whose weight is sometimes not the only source of danger (the load may, for example, be radioactive material or a bucket filled with molten metal).

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

[0004] A safety brake is specifically configured to activate when it is no longer supplied with electricity (in the event of a power failure): this is called a fail-safe brake or negative brake. Disc brakes have become the standard since the 1960s for this purpose, in particular because their overheating poses few or no problems.

[0005] A disc safety brake generally comprises:

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

[0007] - a clamp, comprising two plates adapted to clamp the disc, which The plates are generally equipped with friction pads,

[0008] - for each plate or for one of the two plates only, a spring to washers configured to apply pressure to said plate in the direction of brake closure, that is, in such a way as to push and maintain pressure on the plates against the disc and thus tighten the clamp,

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

[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 mid-air.

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

[0012] 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 required.

[0013] Being by definition managed by a hydraulic system, already integrated into the brake or not, hydraulic brakes include a main hydraulic chamber for the current management of the brake, and they are generally equipped with a "lowering option" which allows taking control of the hydraulic management system of the brake.

[0014] In all cases, the brake includes a hydraulic chamber into which a pressurized fluid (for example, oil) can be injected. This hydraulic chamber bears against one end of the brake's washer spring so as to compress the spring in the direction of brake opening. In the following, this hydraulic chamber is referred to as the brake release hydraulic chamber, including in the case of an electro-hydraulic brake where the chamber is not only a release chamber but 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 posture because of the 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 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 back pressure in the hydraulic chamber of the brake, which opposes 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 retain the load, the 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 rate.

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

[0021] Thus, known lowering devices are very difficult to operate and do not allow the load to be lowered slowly and in a 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 can ultimately react in an all-or-nothing fashion: while the brake is still engaged, a single additional action on the pump lever can cause a rapid and significant increase in pressure in the hydraulic release chamber, resulting in the brake opening and the subsequent drop of the load.

[0022] In addition, not only is the device devoid of means of controlling the pressure in the hydraulic release chamber, but also 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 pressure of fluid in the hydraulic chamber in order to slightly close the brake so as to slow the fall of the load.

[0023] It should be noted that the "equilibrium pressure" of the brake refers to the fluid pressure in the hydraulic release chamber that compresses the spring with washers (in the direction of brake opening) without separating the pads from the disc; in other words, the fluid pressure that allows the hydraulic chamber to exactly counteract the force exerted by the spring on the caliper plates to retain the load. When this equilibrium pressure is reached in the hydraulic chamber, the load is no longer retained by the brake, even though it is not fully open.

[0024] In order for the load to be lowered slowly, progressively and in a 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 close enough to it so that the plates press sufficiently on the disc to slow the descent of the load. Description of the invention

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

[0026] To this end, the invention proposes a hydraulic lowering device for a safety brake on a lifting machine, intended for use with a brake equipped with a hydraulic release chamber and a fluid inlet connection, referred to as the release connection. The lowering device comprises 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 reservoir to inject, under pressure, fluid from the reservoir into the accumulator. - a three-way pressure regulator comprising a mechanical control input for setting a setpoint value, a fluid inlet connected to the accumulator, a first fluid outlet connected to the fluid outlet of the lowering device, and a second fluid outlet, called the 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 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 of energy; it operates the pump to pressurize the fluid in the accumulator until a pressure is reached in the accumulator corresponding, for example, to the maximum permissible pressure in the hydraulic chamber of the brake or, preferably, to the maximum permissible pressure in the accumulator,

[0029] - in a second stage, the operator focuses on the actual piloting; He can adjust the pressure in the hydraulic chamber of the brake at will by manipulating the manual actuation device 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 chamber for releasing the brake, and the injection of this fluid into said chamber, that is to say the decoupling between the physical action of pumping (which requires power) and the action of adjusting the pressure (which requires finesse, precision, and attention), this decoupling being made possible by the provision of an ac- accumulator in the lowering device;

[0032] - the 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; the 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] Furthermore, 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 controller input is greater than the regulator's output pressure, i.e., the fluid pressure in the hydraulic brake release chamber, the pressure regulator connects the fluid inlet and 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 allows the brake to be weakened;

[0035] - if the setpoint value is lower than the fluid pressure in the chamber hy During the brake release procedure, the regulator connects the regulator's fluid outlet to the drain, i.e., the brake and the reservoir respectively; the fluid flows from the hydraulic release chamber towards the reservoir, thus strengthening the brake.

[0036] - if the setpoint value is equal to the fluid pressure in chamber hy brake release procedure, the pressure regulator closes the three channels, this corresponds to a stable lowering phase where the braking force is slightly less 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 that a lowering operation can take several hours depending on the load involved.

[0038] In addition, the device according to the invention has the advantage of being compatible with the vast majority of known safety brakes, in particular with all hydraulically actuated safety brakes 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 according to any technically possible and operational combination.

[0040] In certain embodiments, the lowering device includes a safety stop device, referred to as a dead man's safety device, comprising a safety lever configured to be able to be moved by an operator between a passive locking position that prevents 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 by the operator.

[0041] The dead man's safety device ensures a 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 fluid pressure 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 to measure 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 (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 inlet pressure of the pressure regulator, and on the other hand, the pressure in the hydraulic brake release chamber, which corresponds to the fluid pressure at the fluid outlet of the device and preferably also corresponds to the outlet pressure of the pressure regulator. The usefulness of these pressure sensors and associated display means will be better understood upon reading the detailed description below.

[0045] In certain embodiments, the lowering device includes, 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 deadman's switch and with a pressure limiter (described later).

[0046] In certain embodiments, the lowering device comprises a mobile trolley on which all the components of the device are mounted. This mobile trolley contributes to the ergonomics of the device according to the invention, in that it allows the operator to easily position themselves in the most suitable location to control the lowering.

[0047] In certain embodiments, the pump may be: a hand pump, for example a piston pump activated manually by a lever; a motorized pump, for example a rotary gear pump associated with a screwdriver, the pump comprising a gear having a recess for receiving a screwdriver bit for the purpose of driving said gear in rotation by said screwdriver. The screwdriver is equipped with a battery so that it can be powered under all circumstances (in particular in the event of a power outage).

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

[0049] In certain embodiments, the lowering device comprises: - a main borehole block to which are connected the tank, the pump, and a pressurization hose linking the accumulator to said main borehole block, and - a secondary bored block to which are connected the pressure regulator, a supply hose connected to the accumulator via the main bored block, a return hose connected to the tank via the main bored 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 tank, configured to limit the pressure of fluid 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 certain embodiments, which 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 lever is in the passive locking position and to be open when the safety lever is in the active unlocking position.

[0053] The invention extends to a method for lowering a load onto a lifting device, characterized in that it uses a lowering device as previously defined, and in that it comprises: - a pressurization stage of 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 outlet of the pressure regulator using the manual actuation device of the pressure regulator's control input in order to control the lowering of a load carried by the lifting equipment, - the pressurization and piloting stages being carried out successively, independently of each other.

[0054] Preferably, the accumulator is pressurized until the maximum pressure it can withstand is reached. During lowering, if necessary—that is, if the pressure at the inlet of the pressure regulator becomes insufficient—the operator can stop the load's descent by setting the regulator to a sufficiently low setpoint to engage the brake, cease piloting the accumulator to repressurize it using the pump, and then resume piloting once the accumulator has been repressurized. Preferably, the operator repressurizes the accumulator until the maximum permissible pressure at the regulator inlet is reached, thus avoiding the need for frequent repressurization. Brief description of the drawings

[0055] The invention, according to an exemplary embodiment, will be better understood and its advantages will become more apparent upon reading the following detailed description, given by way of example and in no way limiting, with reference to the accompanying drawings in which:

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

[0057] [Fig.2] [Fig.2] represents an example of the embodiment of [Fig.1], 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 construction of a hydraulic lowering device according to the invention;

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

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

[0061] Identical elements represented in the aforementioned figures are identified by identical numerical references.

[0062] Figures 1 and 2 represent a first 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 embodiment and the third embodiment shown in Figures 4 and 5.

[0063] The lowering device according to the invention in [Fig. 1] 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 that can be manually actuated 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 below),

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

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

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

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

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

[0073] - a fluid outlet 18 to which the operator connects the end of a hose (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 port 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 includes two pumps, one of which is a submersible pump 3' driven by a screwdriver 11, similar to the pump of the second example, and a hand pump 3 operated 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 embodiments, with the exception of the presence of two pumps which only concerns the third example.

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

[0079] The pumps 3 and 3' are connected on one side to the reservoir 1 and on the other side 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 flexible 15, called the pressurization flexible, 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 being inflated beyond its maximum permissible pressure by returning the pumped fluid to the reservoir 1 when this pressure is reached.

[0081] In addition, as is customary, the tank 1 is equipped with a level detector 12.

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

[0083] The collar manometer 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 manometer 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 port 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 setpoint 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 actuates the handwheel 5 to decrease the set pressure, the outlet pressure P2 decreases and the fluid flows in the opposite 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, provided in the secondary drilled block 14, and 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 line 26 to protect the brake. If, through carelessness or error, the operator sets a pressure at the control input of the pressure regulator 4 that exceeds the pressure withstanding the hydraulic chamber for releasing the brake, the pressure limiter 27 opens and some of the fluid is directed to the reservoir instead of being sent to the brake.

[0087] The presence of this pressure limiter 27 allows the lowering device to be used safely for any type of brake, not only for brakes whose hydraulic release chamber can withstand up to 180 bar (such as a safety brake for a lifting device capable of lifting 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 to reduce the risk of brake damage is to limit the pressure PI to which the accumulator is initially pressurized, by stopping the accumulator pressurization step 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's device includes 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]) depressed 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 line 26 in the event of exceeding the maximum pressure that the brake can withstand.

[0089] Releasing the safety lever 7 causes the progressive stop 24 to return, the solenoid valve 25 to open and the circuit at the outlet of the pressure regulator (including the hydraulic chamber for releasing the brake) to drain into the reservoir 1, 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 solenoid valve 25, but also the closing of solenoid valve 23, which consequently isolates the accumulator 2 from the rest of the circuit. Solenoid valve 23 is optional; it complements solenoid valve 25 to ensure very rapid brake closure, avoiding the simultaneous emptying and filling of the brake release hydraulic chamber. Solenoid valve 23 thus reduces the brake's return time.

[0092] The illustrated deadman's safety device (with its lever 7, two solenoid valves, and two progressive stops) is described only as a non-limiting example. A person skilled in the art is generally capable of designing a deadman's safety device using their general knowledge. As an alternative, a safety device controlled by a customer-supplied detection system such as overspeed, overheating, or a timer could be provided. This alternative is less advantageous because it requires equipping the device with a battery to power the detection means in the event of a power failure.

[0093] In the example illustrated in [Fig. 5], a flow restrictor 37 is further provided between the accumulator and the reservoir. This restrictor is used in ON / OFF mode as a valve, in order to allow drainage (in the ON position) from the accumulator 2 to the reservoir 1 for the purpose of disengaging the lowering device.

[0094] In the lowering process according to the invention, the operator first creates an energy reserve by fully inflating the accumulator using pump 3 or pump 3'. This operation can be repeated as many times as necessary. necessary during the lowering, taking care first to block the load by reducing the setpoint value at the control input of the pressure regulator.

[0095] He then actuates the handwheel 5 to increase the pressure in the brake, more or less rapidly, 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 (it is not a technical specification of the brake alone); it is therefore unknown to the operator at the beginning of the lowering process.

[0096] The pressure gauge 9 allows the operator to determine the equilibrium pressure at the moment the load begins to descend abruptly. The operator then sharply turns the handwheel in the opposite direction to close the brake and stop the load. Now that the operator has an approximate idea of ​​the equilibrium pressure, they can more precisely control the handwheel to quickly return to this pressure and then gradually exceed it to slide the load. The operator can then easily control the load's descent speed by precisely adjusting the pressure regulator 4 around the equilibrium pressure.

[0097] That being said, a lowering device without a pressure gauge 9 conforms to the invention. The operator must then control the regulator blindly, without ever knowing the equilibrium pressure value. While not essential, the pressure gauge 9 helps to reduce operator stress.

[0098] The pressure gauge 8 allows the operator to know the state of the energy reserve available in the accumulator 2. This allows them to anticipate a possible pressure drop and the need to repressurize the accumulator. The pressure gauge 8 is an optional component of the lowering device according to the invention, as it is not essential for the operator's safety or for the success of the lowering operation (a pressure drop at the regulator inlet would result in the brake closing and the load stopping). Like the pressure gauge 9, the pressure gauge 8 contributes to the ergonomics of the lowering device and helps reduce operator stress.

[0099] In addition to pressure gauges 8 and 9, the lowering device illustrated in [Fig. 5] includes two other pressure ports, 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 chamber for releasing the brake.

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

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

Claims

Demands

1. Hydraulic lowering device for a safety brake of a lifting machine, intended for use with a brake having a hydraulic release chamber and a fluid inlet connection, referred to as the release connection, the lowering device comprising: - a fluid reservoir (1), and - a fluid outlet (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 under pressure into the accumulator fluid present in the reservoir, - a three-way pressure regulator (4) comprising a mechanical control input for setting a setpoint value, a fluid inlet connected to the accumulator (2), a first fluid outlet connected to the fluid outlet connection (18) of the lowering device, and a second fluid outlet, referred to as the drain, connected to the reservoir (1),- a component (5) for manual actuation by an operator of the mechanical control input of the pressure regulator (4), - an extension for the fluid connection from the fluid outlet (18) to the release connection of the safety brake.

2. A lowering device according to claim 1, comprising a safety stop device, referred to as 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 chamber for releasing the brake and an active unlocking position which permits the injection of fluid into the hydraulic chamber for releasing the brake, 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 claim 1 or 2, comprising: - a first pressure sensor (8) for measuring the fluid pressure 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 fluid pressure at the fluid outlet of the lowering device or at 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 any 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 any one of claims 1 to 5, comprising a movable trolley (31) on which all the components of the lowering device are mounted.

7. Lowering device according to any one of claims 1 to 6, the pump is selected 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 any one of claims 1 to 7, comprising: - a main drilled block (13) to which are connected the reservoir (1), the pump (3), a pressurizing hose (15) connecting the accumulator (2) to said main drilled block, and - a secondary drilled block (14) to which are connected the pressure regulator (4), 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 any one of claims 1 to 8, comprising a pressure limiter (22) between the accumulator (2) and the reservoir (1), configured to limit the pressure of fluid injected into the accumulator.

10. Lowering device according to claim 5, wherein the return circuit (30) includes another pressure limiter (27) configured to limit the fluid pressure injected into the hydraulic brake release chamber via the fluid outlet port (18).

11. A lowering device according to any one of claims 1 to 10, wherein the deadman'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 handle (7) is in the passive locking position and for 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. A 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 pressurization step of the accumulator (2) during which at least part of the fluid present in the reservoir (1) is injected into the accumulator (2) by activation of the pump (3, 3'), - a step of controlling the pressure at the outlet of the pressure regulator (4) using the manual actuation device (5) of the control input of the pressure regulator in order to control the lowering of a load carried by the lifting equipment, - the pressurization and piloting stages being carried out successively, independently of each other.

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