Anti-lock device for wheel and brake system equipped with such device

Abstract

The invention relates to an anti-lock device (1) for a wheel, which is arranged in a hydraulic pressure circuit between a master cylinder (2) and at least one brake caliper (3) of the wheel, in particular for an aircraft. According to the invention, the device comprises: a centrifugal element (4) attached to a rim (5) of the wheel and movable from a retracted position when the wheel is rotated at a speed below a threshold rotational speed to a deployed position due to centrifugal force when the wheel is rotated at a speed beyond the threshold rotational speed; a pressure regulating system (6) comprising a hydraulic inlet (6a) connected to the master cylinder (2) and a hydraulic outlet (6b) connected to the hydraulic inlet of the brake caliper (3), the pressure regulating system (6) is movable between a hydraulic circuit closed position when the centrifugal element (4) is in the retracted position and a hydraulic circuit open position driven by the centrifugal element (4) in the deployed position.

Description

Technical Field

[0001] This invention relates to the technical field of braking systems for vehicles, and more specifically to anti-lock braking systems (ABS) for wheels. The device is particularly applicable to, but not limited to, braking systems for light aircraft (i.e., ULM type), or more generally to aircraft weighing less than 5.7 tons. Background Technology

[0002] In traditional braking systems, particularly those used in aircraft, hydraulic pressure is typically applied to the brake calipers to apply braking force to the brake discs mounted on the wheels. However, in certain situations, especially during emergency braking, the wheels may lock up, causing the vehicle to lose control.

[0003] To address this problem, anti-lock braking systems, also known as "anti-skid" systems in English, have been developed.

[0004] The anti-skid system is designed to improve braking performance and help maintain the aircraft's directional stability during the critical phases of takeoff and landing.

[0005] One known anti-skid system uses sensors to measure the speed of an aircraft's wheels during braking. If the sensors detect that one of the wheels is beginning to lock up, the anti-skid system automatically intervenes to reduce the braking pressure on that particular wheel. By reducing the braking pressure, the anti-skid system allows the wheel to continue rotating, thereby preventing wheel lock-up and loss of aircraft control.

[0006] Wheel lock-up can lead to several adverse consequences, including increased braking distance, excessive tire wear, loss of control and skidding, and even loss of directional control in aircraft.

[0007] Existing anti-slip systems are typically expensive, complex, and require power, which can be problematic, for example, in the event of an electrical system failure.

[0008] Furthermore, integrating the anti-skid system into the hydraulic circuit of the braking system may require significant modifications to the existing braking system, which can be expensive and complex.

[0009] Documents US4811994, US4809823 and US3632176 describe the prior art. Summary of the Invention

[0010] Furthermore, integrating the anti-skid system into the hydraulic circuit of the braking system may require significant modifications to the existing braking system, which can be expensive and complex.

[0011] For this purpose, a wheel anti-lock braking system has been developed, which is arranged in a hydraulic pressure circuit between the master cylinder and at least one wheel brake caliper.

[0012] According to the invention, the device includes a centrifugal element attached to the wheel rim, which is movable from a retracted position when the wheel rotates at a speed below a threshold speed to an extended position due to centrifugal force when the wheel rotates at a speed above the threshold speed. This feature avoids the use of electronic sensors to detect rotational speed, thereby improving system reliability and eliminating the need for a power supply.

[0013] Furthermore, the device of the present invention includes a pressure regulating system comprising a hydraulic inlet connected to the master cylinder on one side and a hydraulic outlet connected to the hydraulic inlet of the brake caliper. The pressure regulating system is movable between a hydraulic circuit closed position when the centrifugal element is in the retracted position and a hydraulic circuit open position driven by the centrifugal element in the deployed position, in which the centrifugal element releases the circuit.

[0014] In reality, the pressure in the caliper is opposite to the centrifugal force. In other words, there is a pressure balance between the pressure generated by the deployment of the centrifugal element and the pressure inside the caliper. The lower the wheel speed, the smaller the centrifugal force needed to maintain the pressure, and therefore the pressure in the caliper will push the regulating system back to the hydraulic circuit closed position.

[0015] Below the threshold speed, there is no further braking. To compensate for this deficiency, the braking system can be equipped with two brake calipers, or a bypass system can be installed, as described below.

[0016] Another solution involves installing a preloaded spring to push the regulating system into the intermediate hydraulic circuit open position.

[0017] In this way, once the centrifugal element can no longer maintain the pressure, the spring takes over and ensures a lower pressure. For example, if the pressure is regulated to 40 bar by the centrifugal element, the pressure can be reduced to 15 bar instead of 0 bar by the preloaded spring when the wheel rotates at a speed below the threshold speed.

[0018] According to a particular embodiment, the device includes a wheel hub, a hydraulic circuit pressure regulating system integrated into the wheel hub, and the wheel hub includes:

[0019] - A lateral hydraulic inlet, which is connected to the master cylinder on one side and to the hydraulic inlet of the pressure regulating system on the other side;

[0020] - An axial hydraulic outlet, which is connected on one side to the hydraulic outlet of the pressure regulating system and on the other side to the hydraulic inlet of the brake caliper.

[0021] This allows for improved integration of pressure regulation systems, reduces the complexity of braking systems, and makes installation in existing braking systems easier.

[0022] According to a particular embodiment, the pressure regulating system includes a rod slidably mounted axially in the hub, which is intended to be actuated by a centrifugal element in an extended position and to actuate a valve to switch the hydraulic circuit from a closed position to an open position. This provides a smooth transition between the open and closed positions of the hydraulic circuit, thereby improving the efficiency of the braking system.

[0023] In a particular embodiment, the centrifugal element includes at least one pivoting arm, such as an L-shaped arm, having a first counterweight end and a second end, the second end being designed to push a rod when the arm pivots to the extended position. This particular design ensures good sensitivity to centrifugal forces, thereby improving system accuracy.

[0024] The valve is, for example, in the form of a tubular piston with two shoulders defining an annular chamber between them. The piston includes a bore located between the shoulders to form a hydraulic inlet for the pressure regulating system and to communicate the annular chamber with the inside of the piston. The annular chamber communicates with a hydraulic inlet to the hub, and the piston's rod-opposite end includes a hydraulic outlet for the pressure regulating system communicating with a hub outlet, which is closed by a ball joint. The ball joint is designed to be pushed by a protrusion fixed to a stationary portion of the hub when the valve is actuated by the rod, thereby opening the hydraulic circuit.

[0025] Preferably, the spherical element returns to the closed position of the pressure regulating system outlet by a spring arranged in the tubular piston, thereby ensuring precise control of the hydraulic pressure in the braking system.

[0026] Therefore, the present invention provides a reliable and simple technical solution that is easy to integrate into existing braking systems, thereby improving the safety and efficiency of braking systems, especially for aircraft.

[0027] Preferably, the centrifugal element includes a base to which two arms are hinged, intended to be positioned at the hub of a rim, the arms being radially opposite to the base, and the base being secured to the rim by a clamping system comprising at least two rods screwed into the base, the at least two rods being radially opposite to the base and terminating at shoulder ends, such that tightening the rods clamps the arms of the rim and securely fixes the centrifugal element to the rim.

[0028] The present invention also provides a wheel braking system including at least one brake caliper, which is hydraulically connected to the hydraulic outlet of the master cylinder via the aforementioned anti-lock braking device.

[0029] However, in this configuration with a single caliper, if the anti-lock braking system does not include a preloaded spring as described above, it means that the braking system will no longer function below the threshold speed.

[0030] To overcome this drawback, a bypass line, known in English as a "bypass," can be provided to the braking system. This includes pressure regulating devices, such as valves or pressure regulators, and also hydraulically connects the brake calipers to the hydraulic outlet of the master cylinder.

[0031] In this way, if a relatively high pressure, adjustable according to the pressure regulator, is applied to the brake pedal, the pressure bypasses the anti-lock braking system and is injected into the caliper to allow braking.

[0032] In another embodiment, the wheel includes a second brake caliper that is hydraulically and directly connected to a second hydraulic outlet of the master cylinder. This allows the device to be easily integrated into existing braking systems without major modifications.

[0033] In this configuration, when wheel rotation is impeded or significantly reduced, the system allows one of the brake calipers to stop working, resulting in a 50% reduction in braking power at the wheel. Of course, this 50% reduction can be adjusted by changing the diameter of the caliper piston. Attached Figure Description

[0034] Figure 1 It is a perspective view of the wheel rim including the braking system, with two calipers, anti-slip devices, and a hydraulic circuit with a master cylinder.

[0035] Figure 2 This is a view showing the positioning of the master cylinder of the aircraft brake pedal system.

[0036] Figure 3 This is a longitudinal sectional view of the main cylinder implemented in this invention.

[0037] Figure 4 This is an exploded perspective view of a braking system and an aircraft wheel rim that integrate the anti-skid device according to the present invention.

[0038] Figure 5 yes Figure 4 A longitudinal sectional view of the braking system and wheel rim with integrated anti-skid device assembled in the middle.

[0039] Figure 6 This is a perspective and longitudinal sectional view of the tubular piston of the pressure regulating system implemented in this invention.

[0040] Figure 7 It is a perspective view of a wheel rim including a braking system according to another embodiment, having a single caliper, anti-slip device, and showing a hydraulic circuit with a master cylinder and bypass line.

[0041] Figure 8 yes Figure 4 A longitudinal sectional view of the braking system and wheel rim with integrated anti-skid device assembled in the middle, including a preloaded pressure-maintaining spring. Detailed Implementation

[0042] Reference Figures 1 to 8 The present invention relates to an anti-lock braking system (1) for wheels during braking, ideally designed for light aircraft, commonly referred to as an "anti-skid device". The device (1) is positioned in a hydraulic pressure circuit that connects a master cylinder (2) to at least one wheel brake caliper (3).

[0043] Preferably, the braking system includes two calipers (3), wherein the first caliper is hydraulically connected to a first hydraulic outlet of the master cylinder (2), and the second brake caliper (3) is hydraulically connected to a second outlet of the master cylinder (2) via an anti-lock braking device (1).

[0044] In this way, when the device (1) according to the invention is activated, it prevents pressure from being distributed to one of the calipers (3), thus reducing braking power by 50% in the example above.

[0045] refer to Figure 2 It shows a brake pedal system for a light aircraft, which has two brake pedals, one for each main landing gear wheel, and each pedal actuates the master cylinder (2) via a push rod (2a).

[0046] Each master cylinder (2) has two push rods (2a), specifically two coaxial and opposite independent hydraulic outlets (2b) and two independent hydraulic inlets (2c). Thus, when the pilot presses the brake pedal, each push rod (2a) applies force to the master cylinder (2).

[0047] refer to Figure 3 The master cylinder (2) comprises two distinct chambers (2d), each connected to a different braking circuit for each caliper (3). Inside each chamber is a piston that moves when the brake pedal is depressed. The pressure applied to the brake fluid by the piston's movement is transmitted to the hydraulic lines of the braking system.

[0048] When hydraulic pressure is generated, the hydraulic pressure is distributed to the brake caliper (3), causing the brake pads to press against the brake disc, thereby slowing down or stopping the rotation of the wheel.

[0049] Reference Figures 4 to 6 The anti-slip device (1) according to the present invention mainly comprises a centrifugal element (4), which is firmly attached to the wheel rim (5). The centrifugal element (4) can be in a retracted position (e.g., Figure 5As shown, the movement occurs between the wheel rotation speed (observed when it is below a certain threshold speed (e.g., 15 km / h)) and the unfolded position (caused by centrifugal force when the wheel is above the threshold speed (e.g., 20 km / h)). The use of this centrifugal element (4) eliminates the need for electronic sensors, thus increasing the robustness of the device (1) and reducing maintenance.

[0050] In addition to the centrifugal element (4), the device (1) integrates a pressure regulating system (6). This system includes a hydraulic inlet (6a) connected to the master cylinder (2) and a hydraulic outlet (6b) connected to the hydraulic inlet of the brake caliper (3). The pressure regulating system (6) is designed to operate in the hydraulic circuit closed position (e.g., Figure 5 As shown, the centrifugal element (4) moves between the retracted position (which prevents pressure distribution to the caliper (3)) and the hydraulic circuit open position (when the centrifugal element (4) is deployed, which allows pressure distribution to the caliper (3)). This feature ensures precise modulation of hydraulic pressure according to wheel speed, thus preventing the risk of wheel lock-up during braking.

[0051] The pressure regulating system (6) is preferably integrated into the wheel hub (7), which simplifies the design of the braking system and facilitates installation. The wheel hub (7) includes a lateral hydraulic inlet (7a) connected to the master cylinder (2) and the pressure regulating system (6), and an axial hydraulic outlet (7b) connected to the outlet (6b) of the pressure regulating system (6) and the brake caliper (3).

[0052] The pressure regulating system (6) includes a rod (8) that is slidably and sealably mounted axially in a hub (7). The rod is designed to be actuated by a centrifugal element (4) in an extended position and to actuate a valve (9) that is also slidably and sealably mounted in the hub (7).

[0053] The centrifugal element (4) is equipped, for example, with an L-shaped arm (4a), which in the illustrated embodiment are two arms (4a) for balancing and pivoting, having a first counterweight end (4a1) and a second end (4a2), the second end being intended to push the rod (8) when pivoting to the unfolded position.

[0054] The centrifugal element (4) includes a base (4b) to which an arm (4a) is hinged. The base (4b) is intended to be positioned at the hub of a rim (5). The arm (4a) is substantially radially opposed to the base (4b). The base (4b) is secured to the rim (5) by a clamping system comprising two rods (4c) screwed into the base (4b) and end-to-end at a shoulder end (4c1). Tightening the rods (4c) clamps the arm of the rim (5) like a plier, thereby securely fixing the centrifugal element (4) to the rim (5).

[0055] Reference Figure 6 The valve (9), designed to be actuated by a rod (8), is, for example, in the form of a tubular piston with two shoulders (9a) defining an annular chamber (9b) between the two shoulders. The piston includes a bore (9c) located between the two shoulders (9a) to allow communication between the annular chamber (9b) and the interior of the piston, and to form a hydraulic inlet (6a) for the pressure regulating system (6). A hydraulic outlet (6b) is integrated at one end of the piston opposite to the rod (8), which communicates with a hub outlet (7b).

[0056] Preferably, the ball (10) is used to close the hydraulic outlet (6b) of the valve (9). When the valve (9) is actuated by the rod (8), the ball is pushed by a protrusion (11) fixed to the stationary portion (12) of the hub (7) to open the hydraulic circuit. A spring (13) is arranged in the tubular piston to return the ball (10) to the closed position of the hydraulic outlet (6b) of the pressure regulating system (6). The stationary portion (12) with the protrusion is, for example, in the form of a plug that closes the end of the hub (7), in which a channel is provided to form the hydraulic outlet (7b) of the hub (7). The channel opens eccentrically in the hub (7) relative to the protrusion (11).

[0057] In another embodiment, the braking system may include only one caliper (3) per wheel. In this configuration, and in order to maintain operational braking when the wheel is rotating at a speed below a threshold speed, the anti-lock braking device (1) may include a preloaded spring (15) which is configured to push the pressure regulating system (6) to an intermediate hydraulic circuit open position to ensure a certain amount of pressure.

[0058] This example is in Figure 8 As shown, the spring (15) is positioned around the push rod (8) in the hub body (7), adjacent to a portion of the hub and opposite the valve (9).

[0059] exist Figure 7 In another example shown, the braking system includes a bypass line (14), also known as a “bypass” in English, equipped with a pressure regulating device, such as a valve (14a) or regulating valve (14b), which establishes a hydraulic connection with the brake caliper (3) connected to the hydraulic outlet (2b) of the master cylinder (2).

[0060] When the brake pedal is pressed with relatively high pressure (which can be adjusted according to the characteristics of the pressure regulating device (14a or 14b), the pressure is injected into the caliper (3) by bypassing the anti-lock braking system (1). This configuration has several advantages and technical benefits.

[0061] In this way, even if the anti-lock braking system fails, it can ensure that the brakes continue to operate, thereby improving the overall safety of the system.

[0062] As can be seen from the above, the present invention provides an anti-skid device that does not require a power supply, is reliable in design, and can be easily integrated into existing braking systems without major modifications.

Claims

1. An anti-lock wheel device (1) arranged in a hydraulic pressure circuit between a main cylinder (2) and at least one wheel brake caliper (3), in particular for an aircraft, characterized in that, The anti-locking device for a wheel comprises: - a centrifugal element (4) fixed to the wheel rim (5) and movable from a retracted position when the wheel rotates at a speed lower than a threshold speed to a deployed position due to centrifugal force when the wheel rotates at a speed higher than the threshold speed; - a pressure regulation system (6) comprising a hydraulic inlet (6a) connected on one side to the master cylinder (2) and a hydraulic outlet (6b) connected to the hydraulic inlet of the brake caliper (3), the pressure regulation system (6) being movable between a hydraulic circuit closed position when the centrifugal element (4) is in the retracted position and a hydraulic circuit open position driven by the centrifugal element (4) in the deployed position.

2. The anti-lock braking device (1) for vehicle wheels according to claim 1, characterized in that, The anti-locking device for a wheel comprises a wheel hub (7), the pressure regulation system (6) being integrated into the hub (7) and the hub (7) comprising: - a lateral hydraulic inlet (7a) connected on one side to the master cylinder (2) and on the other side to the hydraulic inlet (6a) of the pressure regulation system (6); - an axial hydraulic outlet (7b) connected on one side to the hydraulic outlet (6b) of the pressure regulation system (6) and on the other side to the hydraulic inlet of the brake caliper (3).

3. The anti-lock braking device (1) for vehicle wheels according to claim 2, characterized in that, The pressure regulation system (6) comprises a rod (8) slidably axially mounted in the hub (7), intended to be pushed by the centrifugal element (4) in the deployed position and intended to push a valve (9) to switch from a hydraulic circuit closed position to an open position.

4. The anti-lock braking device (1) for vehicle wheels according to claim 3, characterized in that, The centrifugal element (4) comprises at least one pivoting arm (4a) having a first weighted end (4a1) and a second end (4a2) intended to push the rod (8) when the arm (4a) is pivoted to the deployed position.

5. The anti-lock braking device (1) for vehicle wheels according to any one of claims 3 to 4, characterized in that, The valve (9) is in the form of a tubular piston comprising two shoulders (9a) between which an annular chamber (9b) is defined, the piston comprising a bore (9c) between the two shoulders (9a) to form the hydraulic inlet (6a) of the pressure regulation system (6) and to communicate the annular chamber (9b) with the inside of the piston, the annular chamber (9b) communicating with the hydraulic inlet (7a) of the hub (7) and one end of the piston opposite the rod (8) comprising the hydraulic outlet (6b) of the pressure regulation system (6) communicating with the hydraulic outlet (7b) of the hub (7), closed by a ball (10) intended to be pushed by a protrusion (11) of a stationary part (12) of the hub (7) to open the hydraulic circuit when the valve (9) is pushed by the rod (8).

6. The anti-lock braking device (1) for vehicle wheels according to claim 5, characterized in that, The ball (10) is returned to the closed position of the hydraulic outlet of the pressure regulation system (6) by a spring (13) arranged in the tubular piston.

7. Antilock wheel device (1) according to any one of the preceding claims, characterized in that The anti-locking device of the wheel comprises a preloaded spring (15) which urges the pressure regulating system (6) into an intermediate hydraulic circuit opening position.

8. Antilock device (1) for vehicle wheels according to any one of the preceding claims, characterized in that, The centrifugal element (4) comprises a base (4b) to which two arms (4a) are hinged, intended to be positioned at the hub of the rim (5), the arms (4a) being diametrically opposite with respect to the base (4b), and the base (4b) is fixed to the rim (5) by a clamping system comprising at least two rods (4c) screwed into the base (4b), diametrically opposite with respect to the base (4b) and ending with a shoulder end (4c1), so that screwing the rods (4c) clamps the arms of the rim (5) and firmly fixes the centrifugal element (4) to the rim (5).

9. A wheel braking system comprising at least one brake caliper (3) which is hydraulically connected to a hydraulic outlet (2b) of a master cylinder (2) via an anti-locking device of the wheel (1) according to any one of claims 1 to 8.

10. The brake system of claim 9, wherein, A by-pass line (14) equipped with pressure regulating means, such as a valve (14a) or a regulating valve (14b), also hydraulically connects the brake caliper (3) to the hydraulic outlet (2b) of the master cylinder (2).

11. The brake system of claim 9, wherein, The wheel comprises a second brake caliper (3) which is hydraulically and directly connected to a second hydraulic outlet (2b) of the master cylinder (2). The wheel comprises a second brake caliper (3) which is hydraulically and directly connected to a second hydraulic outlet (2b) of the master cylinder (2).

Images