Disc brake for lifting equipment, combining a positive brake and a negative brake

Abstract

Hybrid brake for lifting equipment, comprising: an upper plate (2) and a lower plate (3) forming a clamp suitable for clamping a disc (1), the upper plate being carried by a shoe (6) sliding axially in a half-caliper (4); a stack of spring washers (10) arranged in the half-caliper; a negative piston (80) sliding axially in the half-caliper, the negative piston being able to be placed in an open brake position when a first energy source is activated, the negative piston being pushed into a closed brake position by the stack of spring washers when the first energy source is inactive; a positive piston (90) sliding axially through the stack of spring washers (10), the positive piston being able to be placed in a closed brake position when a second energy source is activated, the positive piston being in an open brake position when the second energy source is inactive.Figure for the abridged version: Fig. 1.

Description

Title of the invention: Disc brake for lifting equipment, combining a positive brake and a negative brake. Technical field

[0001] The present application relates to a disc brake particularly suitable for braking heavy loads (for example, more than several tons and up to 50t), such as a brake intended to equip an elevator, a cable car or a lifting device such as a crane, overhead crane, etc. State of the art

[0002] An elevator or lifting device comprises, on the one hand, a high-speed line including a motor (generally with a variable speed drive) and a high-speed shaft driven in rotation by the motor via a coupling system, and on the other hand, a low-speed line including a low-speed shaft and a drum on which the load suspension cables (elevator cabin or load to be lifted) are wound, the low-speed shaft being driven in rotation by the shaft of the high-speed line to which it is connected via a reducer.

[0003] An elevator or lifting device must be equipped with brakes for several functions, including: slowing down and then stopping the elevator or lifting device as it approaches a stopping position (service brake), locking the elevator each time the doors open, or locking the lifting device when it is in its stopping position, i.e., when the load is at the desired height (parking brake). Standards require that the elevator or lifting device also be equipped with a safety brake, also called an emergency brake or "failsafe brake," to slow down, stop, and lock the elevator or lifting device in the event of a power failure or, more generally, in any emergency.

[0004] Service brakes (high speed and low torque) are generally associated with the high speed line, while safety brakes (low speed and high torque) are mounted on the low speed line.

[0005] A safety brake is specifically configured to trigger when it is no longer supplied with electricity (in the event of an electrical failure): this is referred to as a fail-safe brake or negative brake.

[0006] Disc brakes have become the standard since the 1960s for this purpose, in particular because their overheating poses few or no problems. Indeed, under the effect of heat, the discs expand radially and not in the direction of their thickness, so that the braking torque remains controlled.

[0007] A disc safety brake generally comprises:

[0008] - a disc attached to the line to be braked, on either side of which extend the two plates of a clamp suitable for gripping the disc, which plates are fitted with friction pads,

[0009] - for each plate or for one of the two plates only, a spring to washers configured to impose a compressive force on said plate so as to push and maintain pressure on the plates against the disc and thus close and tighten the clamp,

[0010] - a configured hydraulic, electromagnetic, or electromechanical actuator to, when under tension, compress the washer spring so as to move said platter away from the disc to open the clamp and release the rotating disc.

[0011] With regard to elevators, service and parking brakes must be rated for 10 million operations, while the safety brake must be rated for 200,000 uses. Similarly, manufacturers of lifting equipment often require that the parking brakes and safety brakes they integrate into their equipment be guaranteed for 4 million and 200,000 uses, respectively, although no standard currently mandates this.

[0012] Some manufacturers of elevators or other lifting equipment use a single brake to perform both service and parking functions. Because this brake is used more frequently and / or for longer periods, its friction pads wear out more quickly, increasing maintenance costs. For the same reasons, the brake's lifespan decreases, requiring more frequent replacement. All of this results in periods of elevator or lifting equipment downtime that are inconvenient for users (in the case of residential elevators) or costly for the company (in the case of lifting equipment or non-standard elevators used in industry).

[0013] Other manufacturers of elevators or other lifting equipment use the safety brake as a parking brake, which necessitates oversizing the safety brake to ensure it is rated for 4 or 10 million uses instead of 200,000. This means increasing the number of washers in the safety brake to compensate for potential washer breakage that may occur during repeated use. This results in an increase in the brake's size and manufacturing costs. Presentation of the invention

[0014] The invention aims to overcome at least one of the aforementioned drawbacks by providing a brake that can be used simultaneously as a parking brake and emergency brake, or even as a service brake if lifting standards evolve in this direction, without sacrificing safety, the compactness of the brake, or its simplicity of design, and without increasing its manufacturing and maintenance costs.

[0015] Throughout the following, the expression "lifting equipment" encompasses both industrial lifting equipment such as cranes, lifting bridges, etc., and elevators, for industrial or domestic use.

[0016] To achieve the aforementioned objectives, the invention proposes a hybrid brake for lifting equipment, intended to cooperate with a disc of the lifting equipment extending in a plane orthogonal to an axial direction, the hybrid brake comprising:

[0017] - two plates extending parallel to the disk on either side of it, the two plates forming a clamp that can be actuated between an open brake position in which the plates are away from the disc and a closed brake position in which the plates clamp the disc.

[0018] This hybrid brake is characterized in that it comprises:

[0019] - a rigid body comprising a tubular upper part, called a half-stirrup upper, located on one side of the disc, one of the platters, called the upper platter, being supported by a shoe mounted to slide along the axial direction in a central recess passing through the upper half-caliper,

[0020] - a stack of spring washers arranged in the central recess of the half-caliper upper around a central axis parallel to the axial direction, the stack of spring washers can be compressed beyond a level, called emergency braking compression, in which said stack exerts a force on the shoe corresponding to a desired emergency clamping force on the disc,

[0021] - a negative actuator, comprising a negative piston driven by a first source of energy, which negative piston has a face on which rests a lower end of the stack of spring washers, the negative piston being mounted to slide along the axial direction in the central recess of the upper half of the caliper between a high open brake position in which the negative piston compresses the stack of spring washers beyond the emergency braking compression, and a low closed brake position in which the brake is closed and in which the negative piston maintains the stack of spring washers at the emergency braking compression on one side and is in direct or indirect contact with the shoe on the other side,the negative piston being placed in its upper open brake position when the first energy source is activated and in its lower closed brake position when said first energy source is inactive (either because there is an electrical fault or because the first source is not activated or is intentionally deactivated),

[0022] - a positive actuator comprising a positive piston driven by a second source of energy, the positive piston comprising a shaft extending along the central axis through the stack of spring washers, the positive piston being mounted to slide along the axial direction between a high open brake position, in which the brake is open, and a low closed brake position, in which the brake is closed (and more or less tight) and in which a lower end of the shaft is coupled to the shoe, the positive piston being placed in its upper open brake position when the second power source is inactive and being able to be placed in its lower closed brake position when the second power source is activated.

[0023] The brake according to the invention can thus be described as a hybrid brake in that it integrates both a positive actuator which closes the brake (with a more or less significant controlled clamping force) when it is activated and a negative actuator which closes the brake when it is inactive or deactivated.

[0024] In case of emergency, the negative actuator is deactivated and the brake is closed with a desired emergency clamping force, which is fixed by the structure of the stack of spring washers.

[0025] The positive actuator can be used as a parking brake, or even as a service brake subject to changes in standards in this regard, and it must, as such, be sized to be qualified for approximately one million operating cycles (preferably qualified for several million, for example, at least 10 million operating cycles). The positive actuator can also be used for short-term static load holding (short-term parking brake, when the installation is energized, with the negative actuator always on standby to ensure load safety).

[0026] Given its design, the negative brake is automatically engaged in the event of a power failure (secondary power source unavailable and negative actuator inactive). The negative brake can also be used actively for any emergency dynamic braking (in case of any fault) and for long-term static load holding (long-term parking brake, for example, when the installation is taken out of service). The stack of spring washers, which constitutes the negative brake's energy reserve for emergency braking, must therefore be dimensioned to be qualified for 200,000 cycles of use. Since the negative brake is not used as a service brake, the stack of spring washers does not need to be dimensioned for several million cycles, thus limiting its size and cost.

[0027] Moreover, since a single device—and in particular a single body incorporating two types of brake—serves all situations, the size and manufacturing costs of the overall lifting equipment braking system are considerably reduced, without compromising safety. Furthermore, as will become clearer from the detailed description below, the brake design is particularly simple.

[0028] According to a possible feature of the invention, the negative piston comprises a cylindrical upper cavity receiving a lower part of the stack of washers springs, the negative piston further comprising a lower end configured to bear directly or indirectly on the shoe when the negative piston is in the lower position, so that the pressure exerted by the stack of spring washers on the bottom of the piston cavity is transmitted to the shoe (when the negative piston is in the lower position).

[0029] According to one possible feature of the invention, the first energy source (energy source of the negative actuator) is hydraulic, the negative piston having an external shoulder that is oriented towards the disc and that delimits, in the central recess of the half-caliper, a chamber called the negative hydraulic chamber. The filling of said negative hydraulic chamber by the fluid from the first energy source therefore exerts pressure on said shoulder in the opposite direction to the disc, which causes the negative piston to move in the opposite direction to the disc.

[0030] Alternatively, the first energy source can be electromagnetic or electromechanical.

[0031] According to one possible feature of the invention, the second energy source (energy source of the positive actuator) is hydraulic or electromechanical or electromagnetic.

[0032] Conventionally, each plate is equipped with one or more friction pads. According to a possible feature of the invention, the brake includes a wear compensation device between the stack of spring washers and the shoe to compensate for wear of the friction pads.

[0033] Advantageously and according to the invention, this wear compensation device comprises:

[0034] - a thread called the compensation thread, formed on the shaft of the positive actuator between the lower end of the stack of spring washers and the lower end of the shaft,

[0035] - shells called recovery shells, arranged around the thread of each adjustment shell has a threaded face complementary to the adjustment thread.

[0036] - for each recovery shell, a housing provided in the negative piston and in which said shell is housed, the housing having an axial dimension greater than an axial footprint of the compensating shell increased by at least one compensating thread pitch so that the compensating shell can move axially in this housing over an axial distance of at least one thread pitch, the housing also having a radial depth sufficient for the shell to move radially over a radial distance corresponding at least to the depth of the compensating thread pitch so that the tapping of the shell can disengage from the compensating thread,

[0037] - an elastic ring surrounding the shells, exerting pressure on them A centripetal radial force tends to keep the repair shells pressed against the repair thread. For example, the elastic ring bears against a peripheral outer face of the shells opposite their threaded face.

[0038] According to a possible feature of the invention, there are three of the catching shells, uniformly distributed around the catching thread, i.e. arranged on radii forming angles of 120° between them.

[0039] According to one possible feature, the wear compensation device further includes an actuator configured to drive the positive piston in rotation and means for piloting said actuator.

[0040] Wear compensation can thus be done not only automatically by step skipping as explained later in the detailed description with reference to the attached figures, but also in a controlled manner by rotating the positive piston (and therefore the compensation thread) by the aforementioned dedicated actuator.

[0041] The hybrid brake according to the invention can be a sliding brake or a symmetrical brake.

[0042] If the hybrid brake according to the invention is a sliding brake:

[0043] - in addition to the upper half-caliper, the rigid body of the brake comprises a part lower plate, called counter-caliper, located on the other side of the disc, the other plate, called lower plate, being located on this counter-caliper and being fixed relative to it,

[0044] - the brake lacks an actuator for braking on the counter-caliper side; it It therefore preferably includes only the previously defined negative actuator and positive actuator, which are arranged in the upper half-brace,

[0045] - the brake comprises a column on which the rigid body (half-caliper + counter- (bracket) is mounted to slide along the axial direction.

[0046] If the hybrid brake according to the invention is a symmetrical brake:

[0047] - in addition to the upper half-caliper, the rigid body of the brake includes a half-caliper lower, located on the other side of the disc,

[0048] - like the upper plate, the lower plate is supported by a lower shoe mounted sliding along the axial direction in a central recess of the lower half-brace,

[0049] - the brake comprises a second positive actuator and a second negative actuator Arranged in the lower caliper half and configured to move the lower brake shoe, the second negative and positive actuators can be identical to the negative and positive actuators of the upper caliper half, respectively, but arranged symmetrically (with respect to the braking plane represented by the disc) in the lower caliper half. In short, the entire brake assembly can be symmetrical with respect to the disc.

[0050] The invention extends to a braking system comprising a hybrid brake as previously defined and a microprocessor controller(s) to which the positive and negative actuators of said hybrid brake are connected, the controller being configured to use the positive actuator for all dynamic service braking and for all static holding when the lifting equipment is in service, energized and in the absence of a fault ("short-term" static holding), and to use the negative actuator for all dynamic emergency braking and for all static holding ("long-term") when the lifting equipment is taken out of service (i.e. is no longer energized), the negative actuator also being, by its design, automatically triggered without action from the controller for all dynamic emergency braking in the event of an electrical failure.

[0051] The invention extends to a lifting device characterized in that it is equipped with a hybrid brake as previously defined. In the preceding sentence, the expression "a hybrid brake" should not be understood as meaning "one and a half" hybrid brake but as meaning "at least one" hybrid brake, that is to say, one or more hybrid brakes. Brief description of the drawings

[0052] 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:

[0053] [Fig-1] [Fig. 1] is a cross-section by an axial plane of an embodiment of a hybrid brake according to the invention;

[0054] [Fig.2] the [Fig.2] is a symbolic representation of the hybrid brake of the [Fig.1];

[0055] [Fig.3] [Fig.3] is a symbolic representation of a catch-up device wear that can be fitted to a hybrid brake according to the invention, showing the brake in the case of new friction pads and with the positive piston in the high position of the open brake, the negative piston being in the high position;

[0056] [Fig.4] [Fig.4] is a symbolic representation of the catch-up device of wear of the [Fig.3] in the case of new friction pads and with the positive piston in the lower position of the closed brake, the negative piston being in the upper position;

[0057] [Fig.5] [Fig.5] is a symbolic representation of the wear compensation device of [Fig.3] to 5 in the case of worn friction pads, simulating the closing of the positive brake, i.e. the descent of the positive piston towards the disc from its high position, the negative piston being unused and therefore fixed in the high position;

[0058] [Fig.6] [Fig.6] is a symbolic representation of the wear compensation device of [Fig.5] (with worn friction pads), simulating the opening of the positive brake, i.e. the upward movement of the positive piston in the opposite direction to the disc, after braking following the situation in [Fig.5], the negative piston is still fixed in the upper position. Detailed description

[0059] Identical elements represented in the aforementioned figures are identified by identical numerical references.

[0060] Throughout this description, the brake is defined and described in the position in which it appears in the accompanying figures. The terms "up," "down," "upper," "lower," "above," "below," "up," "down," etc., refer to this position and are unrelated to the direction of gravity, as the brake can operate in any position. Thus, for example, since the brake is described in a position in which its actuators are located above the disc, the expression "the piston moves down" is used to mean more generally that the piston in question moves in the direction of the disc (which does not necessarily mean that it follows the direction of gravity), while the expression "the piston moves up" means that the piston moves away from the disc.

[0061] Figure 1 represents a hybrid brake 100 according to the invention, seen in cross-section along an axial plane (plane containing the central axis of the brake body). More precisely, the axial plane in question is a plane of symmetry of the brake.

[0062] The hybrid brake 100 is associated with a disc 1 of a lifting device (not shown), which disc is fixed to a rotating line of said lifting device. The hybrid brake 100 comprises an upper plate 2 equipped with friction pads 7 (also called wear linings) and a lower plate 3, similarly equipped with friction pads 7. The plates and the disc are parallel to each other and orthogonal to a central axis Xi00 of the brake, the reference numeral Xi also designating the axis of rotation of the disc 1, which is parallel to the central axis Xi00. The term "axial direction" refers to the direction of the central axis Xi00 of the brake.

[0063] The hybrid brake 100 further comprises a rigid body including an upper half-caliper 4, hereinafter simply referred to as the "half-caliper," and a counter-caliper 5. The half-caliper 4 is tubular: it includes a central recess 40 extending through it along the axial direction. This central recess 40 is not necessarily cylindrical; it may comprise a series of sections of different diameters forming various internal shoulders. However, for reasons of economy, these different sections preferably all have a circular cross-section to allow for sealing and guidance using conventional gaskets. Other cross-sections (polygonal, for example, particularly square) are nevertheless possible, provided that specific gaskets of complementary shape are used.

[0064] The plate 2 is carried by a shoe 6 mounted to slide inside the central recess 40 of the half-bracket (the plate 2 could, alternatively, correspond to the lower face of said shoe 6), while the plate 3 is carried by the counter-bracket 5 (it is for example fixed on the upper face of the latter).

[0065] The hybrid brake 100 also includes a stack of spring washers 10. The spring washers are chosen for their dimensional characteristics / material / properties (particularly stiffness), just as the brake pads are chosen for their coefficient of friction, depending in particular on the maximum load that the brake is designed to slow. The stack of spring washers is thus dimensioned to generate a clamping force, called the emergency clamping force, inducing (via the brake pads and therefore according to their coefficient of friction) a braking force that must correspond to the braking force required to instantly stop said maximum load.

[0066] The hybrid brake 100 further comprises both a negative actuator 8 and a positive actuator 9, which together with the stack of spring washers 10 form a negative brake (or lack brake) and a positive brake.

[0067] The illustrated hybrid brake 100 is a sliding brake: the two actuators are located on the same side of the disc 1; they both act on the upper plate 2, and the brake has no actuator on the other side of the disc. The upper plate 2 can be moved closer to or further from the disc by the actuators, while the lower plate 3 remains stationary. For the two plates to simultaneously apply a pinching force to the disc, the rigid body of the brake must be able to move axially. To this end, the brake includes a column 12 on which the rigid body of the brake (half-caliper 4 + counter-caliper 5) is mounted to slide along the axial direction, via a bracket 120 which, in this example, extends from the counter-caliper 5, the bracket 120 and the column 12 thus forming a sliding joint. The column 12 is fixed to a base plate 15.The brake 100 also includes a screw 121 allowing the rigid body to be locked onto the column 12 if necessary, particularly during maintenance operations.

[0068] Alternatively, the hybrid brake could be a symmetrical brake. It would then comprise four actuators, namely a positive actuator and a negative actuator on each side of the disc. The sliding brake is preferred because it offers lower manufacturing and maintenance costs, as well as increased reliability (fewer actuators, therefore less risk of failure or breakage).

[0069] The negative actuator 8 comprises a negative piston 80 mounted to slide in the central recess 40 of the half-caliper.

[0070] The illustrated example uses a hydraulic negative actuator 8. A chamber 81 (called the negative chamber) is therefore provided, which negative chamber 81 is delimited by the The inner face of the recess 40 and the outer face of the negative piston. More precisely, the negative chamber 81 is delimited by an external shoulder 84 of the piston oriented downwards (i.e., towards the disc 1) and an internal shoulder 401 of the half-caliper oriented upwards (i.e., in the opposite direction to the disc 1). This negative chamber 81 is connected to a pressurized fluid supply device (not shown) which constitutes the primary hydraulic energy source for the operation of the negative actuator 8.

[0071] Alternatively, the negative actuator could be electromechanical or electromagnetic, the person skilled in the art being able, without demonstrating inventive activity, to adapt the shape of the half-caliper and to integrate therein, for example, the electromagnets necessary for the movement of the negative piston towards its upper position when the electromagnets are energized for the realization of an electromagnetic negative brake.

[0072] The negative piston 80 has an upper cavity 82 in which a lower part of the stack of spring washers 10 is housed. The lower end of the stack 10 thus rests on a bottom 83 of the upper cavity 82. The upper end of the stack of spring washers 10 also comes to rest against a fixed element of the rigid body of the brake, in this case the lower face of a cover 11 fixed to the top of the half-caliper 4.

[0073] The presence of the cover facilitates maintenance operations by allowing access to the inside of the half-caliper and especially to the stack of spring washers 10: if one wishes to change a broken spring washer for example, it is enough to unscrew the screws which pass through the lower flange of the cover 11 and hold it fixed to the half-caliper 4, then remove the cover to be able to access the stack of spring washers 10 housed in the upper cavity 82 of the negative piston.

[0074] The central recess 40 of the half-stirrup extends axially by a central recess 110 passing through the cover 11 in the axial direction.

[0075] With the stack of spring washers 10 wedged between the lower face of the cover 11 (which is fixed) and the bottom 83 of the upper cavity of the negative piston 80, the compressive force of the stack of spring washers 10 tends to move the negative piston 80 downwards, towards the shoe 6.

[0076] When the chamber 81 of the negative actuator is empty or when a low or zero pressure is imposed on the fluid contained in said chamber, the negative piston 80 descends under the effect of the push of the stack of spring washers 10; the lower end 85 of the negative piston 80 comes to press, directly or indirectly, on a stop or ball joint 97 carried by the lower end of the positive piston 90; the stop or ball joint 97 comes to couple with the shoe 6 and the negative piston pushes the shoe 6 in the direction of the disc 1 as the stack of spring washers 10 relaxes.

[0077] When the friction pads 7 of the plate 2 come into contact with the disc 1. The rigid brake body slides upwards as a single unit along the column 12, while the negative piston 80 continues to descend relative to the caliper half, until the negative piston 80 is in a fully closed brake position. In this position, the friction pads of both plates are in contact with the disc and together exert a clamping force on the disc. The clamping force, known as the emergency clamping force, then applied to the disc depends on the residual compression of the stack of spring washers 10 in this lower position of the negative piston. This residual compression can be adjusted during the brake design by changing the number, stiffness, material, and / or dimensions of the washers used. A desired emergency clamping force can thus be achieved.

[0078] When the negative piston 80 is in the high position as illustrated in [Fig. 1], i.e. when the chamber 81 is filled with a fluid pressure greater than or equal to a given threshold value, the stack of spring washers 10 is compressed beyond the emergency braking compression (which corresponds to the low position of the piston 80).

[0079] In the event of an electrical failure or if the fluid supply to chamber 81 is intentionally stopped, i.e., if the (first) power source of the actuator 8 is inactive (or deactivated), the pressure in chamber 81 drops abruptly and the chamber empties; the negative piston 80 falls to its lowered position and the brake is closed in a fraction of a second. The actuator 8 is therefore indeed a negative actuator.

[0080] The positive actuator 9, for its part, includes a positive piston 90 mounted to slide in the central recesses 40 and 110 of the half-caliper and the cover.

[0081] In the illustrated example, the positive actuator 9 is also hydraulic. It therefore includes a chamber 91 (called the positive chamber) provided above a face of the positive piston 90 oriented upwards (direction opposite to the disc), which chamber is supplied with fluid via a supply conduit 92. This fluid constitutes a second source of energy, which enables the operation of the positive actuator 9.

[0082] The positive piston 90 comprises, from top to bottom, a first section 901 of smaller diameter and then a second section 902 of larger diameter, so that an external shoulder 903 oriented upwards (i.e. in the opposite direction to the disc 1) is formed between the first and second sections of the piston.

[0083] The positive chamber 91 of the positive actuator is delimited by the external face of the positive piston 90 and by the internal face of the recess 110 of the cover above this external shoulder 903.

[0084] The external diameter of the second section 902 of the positive piston is substantially equivalent (within a minimum clearance) to the internal diameter of a corresponding section of the central recess 110 of the cover, to allow the piston 90 to slide about the central axis XiOo while preventing fluid leaks that may occur from chamber 91 between the outer face of the piston and the inner face of the recess 110 in the cover. A seal 93 can be provided to limit these leaks, as well as a groove 94 and a conduit 95 for collecting any leaks downstream (i.e. below) the seal 93.

[0085] The positive piston 90 then includes a third section forming a shaft 904 which passes through the stack of spring washers 10 (the shaft 904 passes through the central hole of each of the spring washers); the shaft 904 also passes through the lower end 85 of the negative piston 80. As already mentioned above, the lower end of the shaft 904 of the positive piston is provided with a stop ([Fig. 1]) or a ball joint ([Fig. 2]), referenced 97 in both cases, which engages in a corresponding recess 60 of the shoe 6 when the positive piston 90 is moved downwards towards the disc 1. Note that the lower end 96 of the piston may be without a ball joint or stop and be configured to couple directly with the shoe 6.

[0086] A bellows 99, fixed on one side to the external face of the lower portion 85 of the negative piston and on the other side to the lower end 96 of the positive piston (for example to the stop or ball joint 97), is advantageously provided to prevent the entry of dust and lining particles which could disrupt the wear compensation system.

[0087] The hybrid brake 100 is further associated with a controller (not shown) which allows the positive actuators 9 and negative actuators 8 to be controlled by acting on the energy supply to these actuators.

[0088] When dynamic service braking or static parking braking is required, the controller commands the injection of pressurized fluid into the positive chamber 91 (activation of the second energy source) of the positive actuator 9, causing the positive piston 90 to move downwards until the stop or ball joint 97 at the lower end of the shaft 904 engages with the shoe 6 and then pushes the latter towards the disc 1. When the friction pads 7 of the backing plate 2 come into contact with the disc 1, the rigid brake body slides upwards as a single unit along the column 12 while the positive piston 90 continues to descend relative to the caliper half, until the friction pads of both backing plates are in contact with the disc and together exert a clamping force on the disc. The clamping force then imposed on the disc 1 is a function of the fluid pressure in the positive chamber 91.The positive brake can therefore be controlled to exert a variable, controlled clamping force.

[0089] Meanwhile, the negative brake 8 is kept open as illustrated in [Fig.1], i.e. a fluid pressure at least equal to a predetermined threshold pressure (capable of compensating the emergency braking compression of the stack 10) is maintained in the negative chamber 81 so that the negative piston 80 remains in the high position as illustrated in [Fig.1].

[0090] The hybrid brake 10 further includes a wear compensation device 13 arranged between the stack of spring washers 10 and the shoe 6, and which will now be described with reference to [Fig.3] to 6, on which only half of the positive and negative actuators of the brake are represented symbolically, the other half being obtained by symmetry with respect to the axis Xi00.

[0091] The wear compensation device 13 comprises:

[0092] - a thread 131, called a compensating thread, formed on a lower portion of the 904 shaft of the positive piston,

[0093] - a plurality of shells 130, for example three shells 130 arranged at 120° one of the others around the 131 thread,

[0094] - an elastic ring 133 surrounding the shells and exerting forces on them centripetal radials which keep the shells in contact with the catching thread 131; each shell 130 has an inner face 132 (face oriented towards the Xioo axis) which is tapped with a screw pitch complementary to the screw pitch of the catching thread 131, so that the tapped inner face 132 of the shells fits into the catching thread 131, under the pressure of the elastic ring 133.

[0095] - for each shell 130, a housing 134 receiving said shell (the housing (being specific to said shell or common to several shells), which housing 134 is provided in the negative piston 80 and is open towards the central axis Xi00, the housing 134 having an axial dimension greater than that of the shell so that the shell can move axially in the housing over a stroke at least equal to the pitch of the thread 131, the housing 134 also having a radial depth sufficient for the shell to move radially over a stroke allowing the tapping 132 to exit the thread 131. Note that the compensation device 13 can comprise a plurality of separate housings 134, in particular one housing per shell 130, or a single circular housing which goes around the shaft 904 (i.e. a circular groove provided in the inner face of the negative piston 80) and which accommodates all the shells 130, or even a plurality of housings each accommodating several shells.

[0096] In [Fig. 3] and [Fig. 4], the brake has unworn friction pads 7. In [Fig. 3], the negative piston 80 is in the open brake position as illustrated in [Fig. 1] (the negative chamber 81 contains pressurized fluid exerting on the piston 80 a force greater than the emergency braking compression force). The positive piston 90 is also in the open brake position (the positive chamber 91 is empty and the shoulder 903 (see [Fig. 1]) of the piston 90 is in contact with or near the cover 11). In this position, each shell 130 is bearing against the upper face 135 (or upper stop) of its housing 134.

[0097] When the positive actuator 9 is actuated, for example for a service operation, the positive piston 90 is pushed downwards by the pressurized fluid injected into the positive chamber 91, and the positive piston 90 moves from its upper position ([Fig. 3]) to its lower closed brake position, illustrated in [Fig. 4]. During this time the negative piston 80 is held fixed in its upper open brake position.

[0098] When the positive piston 90 is in the closed brake position, the friction pads 7 are in contact with the disc 1. As the piston, and therefore the thread 131, descends, the shells follow until they come to rest against the lower face (or lower stop) 136 of the housing. The thread may be lowered slightly further than the shells (as is the case in [Fig. 4]), pushing them radially but without disengaging the threads 132 in the shells from the thread 131.

[0099] Figure 5 illustrates the positive piston 90 in its downward phase, but in the case where the friction pads 7 are worn. In this case, when the positive piston 90 reaches the height of Figure 4 (which corresponds to the lower position of the closed brake when the pads are new), the (worn) pads 7 are still some distance from the disc 1 since they have a reduced thickness due to their wear, and the piston can continue to descend, pushed by the pressurized fluid in the positive chamber 91. The shells 130 can no longer descend, held by the lower face 136 (or lower stop) of the housing. They are then forced to move radially, pushed by the thread 131, until their threaded section 132 disengages from the thread 131.

[0100] It should be noted that the threads of the compensating thread 131 and the tapped hole 132 of the compensating shells advantageously have a triangular cross-section with an upper face orthogonal to the central axis X100 and an inclined lower face. Thus, when the positive piston 90 descends, the compensating thread exerts on the compensating shells 130 a force that comprises both an axial component, which drives the shells downwards, and a radial component, which tends to radially displace the shells outwards when they have come to rest against the lower face 136 of the housing. Conversely, when the positive piston 90 rises, the compensating thread 131 exerts on each shell 130 a purely axial force which ensures that the tapping 132 of the shells remains engaged in the compensating thread 131 of the shaft, including when the shells come to rest against the upper face 135 of the housing.

[0101] Having reached the situation shown in [Fig. 5], the piston 90 continues to descend and the shells skip one or possibly several steps of the thread 131, to end up in the position illustrated in [Fig. 6]. When the positive brake energy source is then deactivated or reduced, the piston 90 rises until the shells come into abuts against the upper face (or upper stop) 135 of the housing and thus stops the piston 90 in a new high position with the brake open ([Fig. 6]). This new high position with the brake open is offset by one or more thread pitches 131 relative to the previous high position, the offset corresponding to the thickness lost through wear by the friction pads 7. Thus, with the same stroke, actuation of the positive piston 90 always closes the brake, whether the pads are worn or not.

[0102] The adjustment mechanism also serves the negative brake, since when the positive brake is not used and the negative piston 80 is in the open brake position (see [Fig. 3] and [Fig. 5]), the shells are always in contact with the upper face 135 of the negative piston housing 134. However, in the example described, the negative piston 80 acts (i.e., indirectly bears against) the shoe 6 via the adjustment device 13, more precisely via the shells 130, the adjustment thread 131, and the lower end 96 of the shaft 904. Thus, when the negative piston 80 is in the open brake position, the lower end of the negative piston is already in indirect contact with the shoe via the shells 130 and the positive piston shaft 904. When the emergency brake is triggered, the negative piston 80 immediately pushes the shoe 6 towards the disc.The relative position of the shells 130 and the thread 131 taking into account the thickness of the friction pads 7 and their possible wear, the closing of the brake (with a predetermined emergency braking torque) is guaranteed with the same stroke of the negative piston 80, whether the pads are worn or not.

[0103] The presence of a positive brake in the hybrid brake does not interfere with the emergency braking function. The negative piston 80 can be actuated (moved down) regardless of the position of the positive piston 90. If the positive piston 90 is in the open brake position, as previously described, the negative piston 80 drives the brake shoes 130 and the shoe 6 from the beginning of its stroke. If the positive brake is in use and the positive piston 90 is, for example, in the closed brake position, the negative piston 80 will only press on the brake shoes 130 and the shoe 6 at the end of its stroke, to ensure that the torque applied to the disc is at least equal to the emergency braking torque.If the positive brake is in use and the positive piston 90 is in an intermediate position (either descending or ascending), the negative piston 80 will take over at an intermediate point in its own stroke when the upper face 135 of the housings 134 comes into contact with the shells 130. It should be noted that, even when it is in the upward phase, the positive piston 90 does not offer resistance to the descent of the emergency negative piston, since the upward movement of the positive piston occurs with negative energy (the chamber 91 empties). Furthermore, the brake 100 includes a return spring 98 configured to return the positive piston 90 to its upper brake position. open. In the illustrated example, the return spring 97 is housed around the shaft 904 inside the stack of spring washers 10. The return spring 98 bears on one side against the bottom 83 of the upper cavity of the negative piston and on the other side against an external shoulder 905 of the positive piston, which shoulder 905 is located at the junction between the sections 902 and 904 of the piston (it is therefore oriented downwards).

[0104] The hybrid brake 100 preferably also includes a recentering device 14 which allows the brake body to be recentered relative to the disc in order to guarantee a symmetrical opening relative to the disc over the entire wear range of the friction pads 7 (the pads of the plate 2 being able to be more or less worn than those of the plate 3. This device will not be described in detail here.

Claims

1. Demands Hybrid brake for lifting equipment, designed to cooperate with a lifting equipment disc extending in a plane orthogonal to an axial direction, the hybrid brake comprising: - two plates (2, 3) extending parallel to the disc on either side thereof, the two plates forming a clamp that can be actuated between an open brake position in which the plates are at a distance from the disc and a closed brake position in which the plates clamp the disc, characterized in that it comprises: - a rigid body (4, 5) comprising a tubular upper part (4), called the upper half-caliper, located on one side of the disc, one of the plates (2), called the upper plate, being carried by a shoe (6) mounted to slide along the axial direction in a central through recess (40) of the upper half-caliper, - a stack of spring washers (10) arranged in the central recess (40) of the upper half-caliper around a central axis (Xi00) parallel to the axial direction, the stack of spring washers (10) being configured to be able to be compressed beyond a level, called emergency braking compression, in which said stack exerts a force on the shoe (6) corresponding to a desired emergency clamping force on the disc, - a negative actuator (8), comprising a negative piston (80) driven by a first energy source, which negative piston has a face (83) on which rests a lower end of the stack of spring washers (10), the negative piston (80) being mounted to slide along the axial direction in the central recess (40) of the upper half-caliper between an upper open brake position in which the negative piston (80) compresses the stack of spring washers (10) beyond the emergency braking compression, and a lower closed brake position in which the brake is closed and in which the negative piston (80) maintains the stack of spring washers (10) at the emergency braking compression on one side and is in direct or indirect contact with the shoe (6) on the other side,the negative piston being placed in its upper open brake position when the first energy source is activated and in its lower closed brake position when said first energy source is inactive, - a positive actuator (9) comprising a positive piston (90) driven by a second energy source, the positive piston comprising a shaft (904) extending along the central axis (Xk») through the stack of spring washers (10), the positive piston being mounted to slide along the axial direction between a high open brake position in which the brake is open, and a low closed brake position in which the brake is closed and in which a lower end (96) of the shaft is coupled to the shoe (6), the positive piston being placed in its high open brake position when the second energy source is inactive and being able to be placed in its low closed brake position when the second energy source is activated.

2. Hybrid brake according to claim 1, characterized in that the negative piston (80) comprises a cylindrical upper cavity (82) receiving a lower part of the stack of spring washers (10), the negative piston further comprising a lower end (85) configured to bear directly or indirectly on the shoe (6) when the negative piston is in the closed brake low position.

3. Hybrid brake according to one of claims 1 or 2, characterized in that the first source of energy is hydraulic, the negative piston (80) having an external shoulder (84) which is oriented towards the disc (1) and which delimits, in the central recess (40) of the half-caliper, a hydraulic chamber (81) called negative chamber.

4. Hybrid brake according to any one of claims 1 or 2, characterized in that the first energy source is electromagnetic or electromechanical.

5. Hybrid brake according to any one of claims 1 to 4, characterized in that the second energy source is hydraulic or electromechanical or electromagnetic.

6. Hybrid brake according to any one of claims 1 to 5, characterized in that each plate (2, 3) is provided with one or more friction pads (7) and in that the brake includes a wear compensation device (13) between the stack of spring washers (10) and the shoe (6) to compensate for the wear of the friction pads.

7. Hybrid brake according to claim 6, characterized in that the wear compensation device (13) comprises: - a thread (131), called the compensating thread, formed on the shaft (904) of the positive actuator between the lower end of the stack of spring washers (10) and the lower end (96) of the shaft, - shells (130), called compensating shells, arranged around the compensating thread (131), each compensating shell (130) having a threaded face (132) complementary to the compensating thread (131), - for each compensating shell (130), a recess (134) formed in the negative piston (80) in which said shell is housed, the recess (134) having an axial dimension greater than an axial clearance of the compensating shell increased by at least one compensating thread pitch so that the compensating shell (130) can move axially in this recess over an axial distance of at least one pitch of threading,the housing also having a sufficient radial depth to allow the shell to move radially over a radial distance corresponding at least to the depth of the compensating thread pitch, - an elastic ring (133) surrounding the shells and exerting a centripetal radial pressure on them tending to keep the compensating shells (130) pressed against the compensating thread (131).

8. Hybrid brake according to claim 7, characterized in that the wear compensation device further comprises an actuator configured to drive the positive piston (90) in rotation and means for piloting said actuator.

9. Hybrid brake according to any one of claims 1 to 8, characterized in that: - in addition to the upper half-caliper (4), the rigid body of the brake comprises a lower part (5), called counter-caliper, located on the other side of the disc (1), the other plate (3), called lower plate, being located on this counter-caliper (5) and being fixed relative to it, - the brake is without an actuator for braking on the side of the counter-caliper (5); - the brake comprises a column (12) on which the rigid body (4, 5) is mounted to slide along the axial direction.

10. A braking system for lifting equipment, comprising a hybrid brake according to any one of claims 1 to 9 and a microprocessor controller(s) to which the positive actuator (9) and the negative actuator (8) of said hybrid brake are connected, the controller being

11. configured to use the positive actuator for all dynamic service braking and for all static holding when the lifting equipment is in service, energized and in the absence of a fault, and to use the negative actuator for all dynamic emergency braking in the event of a fault and for all static holding when the lifting equipment is taken out of service. Lifting device characterized in that it is equipped with a hybrid brake according to any one of claims 1 to 9.