Electro-hydraulic disc brakes

Abstract

The present invention relates to an electro-hydraulic disc brake, and more particularly to an automatic brake pad wear recovery system, the structure of which is based on the interaction between brake arms (2, 3), a brake arm connecting plate (14) and an automatic brake pad wear adjustment and recovery device (7).

Description

Technical Field

[0001] The present invention relates to an electric hydraulic disc brake, and more particularly to an automatic brake pad wear recovery system. Background Art

[0002] Disc brakes are widely used in applications where friction braking is applied. Therefore, a disc brake essentially consists of brake pads that press against the brake disc surface to create friction. The brake pads are mounted on brake shoes that are connected to the clamp or brake arm. In turn, the brake shoes are actuated by springs to close and open the brake.

[0003] In this type of brake, two vertically oriented brake levers or arms have respective first ends pivotally connected to a base and respective second ends connected by an opening and closing mechanism. Thus, the opening and closing mechanism "closes" and "opens" the brake arms, causing the brake pads to come into contact ("closed") or away from ("opened") the disc.

[0004] This type of brake generally presents inconveniences related to brake pad wear, which causes play between the pad and the disc, which, if not compensated, can lead to inefficient braking operation or even failure due to loss of load.

[0005] Various solutions for compensating or restoring brake pad wear are known from the prior art, generally involving the use of pins and auxiliary pistons whose function is to reduce the gap formed between the brake pad and the disc.

[0006] However, this known solution has drawbacks. On the one hand, it is very complex and requires a drive pin or piston. On the other hand, it is also inefficient because considerable compensation occurs after wear.

[0007] Therefore, there remains a need in the art for an effective and safe recovery system for compensating for brake pad wear. Summary of the Invention

[0008] Purpose of the Invention

[0009] One of the objects of the present invention is to provide an electro-hydraulic disc brake with an automatic brake pad wear recovery system.

[0010] Another object of the present invention is to provide an electro-hydraulic disc brake with an automatic brake pad wear recovery system that is safe during use.

[0011] Another object of the present invention is to provide an electro-hydraulic disc brake having an automatic brake pad wear recovery system that is efficient and simple in structure.

[0012] Another object of the present invention is to provide an electro-hydraulic disc brake with an automatic brake pad wear recovery system that allows immediate compensation of brake pad wear.

[0013] Summary of the Invention

[0014] The present invention achieves the aforementioned objectives by an electro-hydraulic disc brake comprising two pivotable vertical brake arms, an upper brake arm pivotally connected to one of the vertical brake arms and a drive system comprising a release actuator, a spring brake mechanism, and an automatic brake pad wear adjustment and recovery mechanism located between the upper portion of the brake arm and a lower joint of the upper brake arm. The brake comprises an inter-arm connecting plate having a brake arm set screw secured with a torque plate washer, and a brake opening clearance adjustment bushing disposed in a hole in the inter-arm connecting plate to create a clearance between the bushing and the hole; and the automatic brake pad wear adjustment and recovery mechanism comprises:

[0015] a bearing receiving the bushing and the guy wire, at least a portion of the outer surface of the guy wire and a portion of the inner surface of the bushing having multiple input trapezoidal threads, and a roller disposed between the bushing and the bearing;

[0016] a spring disposed between the roller and the bearing;

[0017] The bearing has a beveled inner bore, and the bushing has a tapered end whose outer surface defines a corresponding bevel. The interaction between the bevel and the bevel on the bushing's outer surface allows free rotation of the bushing when an axial force is applied in the direction of spring compression, but prevents rotation when an axial force is applied in the opposite direction, as the bevels on both parts act as wedges. The bearing forms a housing that accommodates the rear portion of the guy wire. Preferably, the multi-entry trapezoidal thread has a helix angle of approximately 32°. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention will now be described in more detail with reference to the accompanying drawings, in which:

[0019] Figure 1 - is a perspective front view of the electro-hydraulic disc brake according to the present invention;

[0020] Figure 2 - is a rear view of the electro-hydraulic disc brake according to the present invention, with the release actuator and the spring brake device hidden in the figure;

[0021] Figure 3 - is a rear view of the electro-hydraulic disc brake according to the invention, showing an enlarged detail of the spring brake device and the AA cutout;

[0022] Figure 4- is a rear view of the electro-hydraulic disc brake according to the present invention, with the release actuator hidden and showing an enlarged detail of the BB cutout, as well as the spring brake mechanism;

[0023] Figure 5 - is a perspective top view of the top of the electro-hydraulic disc brake according to the present invention;

[0024] Figure 6 - is a top sectional view of an electro-hydraulic disc brake according to the present invention;

[0025] Figure 7 - is an enlarged sectional view of the automatic brake pad wear adjustment and recovery device of the electro-hydraulic disc brake according to the present invention;

[0026] Figure 8 - is a sectional view of a cable receiving housing of an electro-hydraulic disc brake according to the present invention; and

[0027] Figure 9 - is a partial view of an electro-hydraulic disc brake cable according to the present invention; and

[0028] Figure 10 - is an exploded view of the automatic brake pad wear adjustment and recovery device of the electro-hydraulic disc brake according to the present invention. DETAILED DESCRIPTION

[0029] The following will be based on Figures 1 to 10 The present invention is described with reference to the illustrated embodiments of the present invention.

[0030] Figure 1 A disc brake with an electrohydraulic actuator 1 is shown, with the disc omitted for better visibility. Brake 1 comprises two pivotable vertical brake arms 2, 3; an upper brake arm 4 is pivotally connected to one of the vertical brake arms 3 and to a drive system comprising a release actuator 5, a spring brake device 6, and an automatic brake pad wear adjustment and recovery device 7. Supports (brake shoes) 8 for brake pads 9 are fixed to brake arms 2, 3 on shafts 10. The lower ends of the pivotable vertical brake arms 2, 3 are pivotally mounted to a base 11 via pivots 12 mounted on support members 13 of the base 11.

[0031] The primary components and operation of this type of brake are well known to those skilled in the art, and therefore this disclosure will focus on describing aspects that facilitate a better understanding of the automatic brake pad wear recovery solution.

[0032] Figure 2 A rear view of the brake according to the invention is shown, with the release actuator 5 and the spring brake device 6 excluded.

[0033] As shown in the drawings, the brake of the present invention includes a brake arm connecting plate 14 in which set screws of brake arms 15 and brake opening clearance adjusting bushings 16 are provided.

[0034] like Figure 3 As shown, the brake arm set screw 15 is a screw fixed by means of a self-locking nut and a plate washer with a calculated torque.

[0035] like Figure 4 As best shown in FIG, a brake opening clearance adjustment bushing 16 is disposed in a hole 14f of the plate 14. A calculated gap F exists between the diameter of the bushing 16 and the hole 14f of the plate to ensure clearance between the brake pad and the brake disc when the brake arm moves in the brake opening.

[0036] Figure 5 The top of the hydraulic brake is shown, in which the brake pad wear adjustment and recovery device 7 can be seen between the upper part of the brake arm 3 and the lower joint of the upper brake arm 4. The recovery device is connected to the lower joint of the upper brake arm 4, which is connected to the upper joint of the brake arm 3.

[0037] like Figures 6 to 8 As best shown, the device 7 comprises a bearing 17 located between the top of one of the brake arms 3 and the lower joint of the upper arm 4 of the brake. Positioned in this bearing is a bushing 18 and a cable 19 having a multi-entry trapezoidal thread. The cable 19 extends to a washer 20 provided on the other arm 2 of the brake.

[0038] like Figure 8 As best shown, bearing 17 has an inner bore with a beveled surface 17f, and the bushing has a tapered end whose outer surface defines a corresponding beveled surface 18f. Thus, when interacting with the corresponding beveled surface 18f on the outer surface of bushing 18, beveled surface 17f of bearing 17 acts as a wedge, preventing the bushing from rotating when an axial force is applied to it in the direction of the wedge. In the opposite direction, the wedge loses its locking effect and allows bushing 18 to rotate freely by compressing a spring 21 located behind roller 23. This spring 21 ensures that the tapered end of the bushing is always in a self-locking position, preventing it from rotating even when no force is applied to the guy wire.

[0039] It should be noted that the bearing 17 may be constructed with a closure cover 22 (see Figure 7 and 10 In this case, the inclined surface 17f is the inclined surface of the bearing cover 17.

[0040] When the brake is closed by force from the coil spring brake on the upper brake arm, the brake arm pivots on one of the brake arms by exerting an axial force on the bearing 17 of the brake cable, which in turn transmits this force to the threaded bushing 18 mounted in the cable bearing.

[0041] Bushing 18, in turn, transmits this force to cable 19 via the threads between it and the cable. Due to the inclination of the thread helix (wedge / ramp effect), this force acting on the multi-input trapezoidal thread generates a tangential force on the bushing thread. This tangential force, in turn, generates a torque on bushing 18, which causes bushing 18 to rotate within bearing 17 on cable 19 because its rotation is locked by its attachment to the brake arm connected to the bearing. The same axial force acts on the calculated inclination of the bushing's inclined surface, preventing the bushing from rotating. This axial force, combined with the coefficient of friction between the bearing and bushing's inclined surfaces 17f and 18f, creates a self-locking effect. Since bushing 18 is prevented from rotating, the axial force applied to it is transmitted to cable 19, which is connected to the other brake arm, transmitting the force there. Through the motion of the lever, the brake arm transmits this force to the brake shoe, which generates the braking force.

[0042] As the friction material of the brake pads wears, the brake arms will move further than normal, closing against each other. This movement overcomes the pressure applied by washer 15a, mounted between one of the brake arms 3 and the inter-arm connecting plate 14, because bushing 16 attached to the other arm will interact with circular hole 14f in plate 14 to act as a mechanical stop for the brake arms' movement in the closing direction. Under the force exerted by the brake spring, the brake arms will continue to move relative to washer 15a and bushing 16, causing washer 15a to change position on the plate, allowing the brake to close.

[0043] When the brake is opened, the two brake arms pivot in opposite directions, but their opening travel is limited by the plate 14 located behind them. The circular hole 14f in the plate 14 intersects tangentially with a bushing 16 mounted on one of the brake arms, acting as a mechanical stop and halting the arm's motion. The brake-opening force cannot overcome the pressure of the washer mounted on the other end of the plate. The upper brake arm pivots relative to the brake arm by exerting an opposing axial force on the threaded bushing 18, which in turn exerts an axial force on the guy cable 19, which is secured to the other brake arm via a bearing. This axial force on the bushing compresses the spring 20 located behind the bushing's axial roller, allowing the bushing cone and the restoring bearing cone to separate due to the calculated clearance behind the roller. This movement rotates the bushing relative to the guy cable through the helical tilting action of the multi-input trapezoidal thread, as the axial force no longer acts on the bushing's inclined surface, creating a wedge effect.

[0044] However, in this case, the brake has not yet reached its maximum travel, and the upper brake arm continues to exert an axial force on the brake cable. This force continues to be exerted on the bushing, causing it to rotate on the cable, and this rotational movement of the bushing allows the cable to move relative to the bushing, reducing the distance between the brake arms and compensating for brake pad wear.

[0045] like Figure 8 As best shown in FIG, the tapered end of bushing 18 has a threaded inner surface that is configured to receive corresponding threads from the rear of guy wire 19.

[0046] like Figure 9 As shown, the thread of the guy wire 19 is preferably a multi-entry trapezoidal thread calculated to ensure that the angle α of the thread helix is ​​about 32°. This inclination of the helix allows the rear part to rotate with respect to the guy wire when an axial force is applied to the rear part.

[0047] Of course, the number of threaded entries may vary depending on the helix angle and the size of the guy wire.

[0048] An important point of the present invention is that the bushing 18 and the bearing 17 form a fixed housing, so that the rear of the guy wire 19 can move axially within the housing.

[0049] This construction allows the automatic brake pad wear recovery system to be safe, as the rear of the cable 19 does not protrude "outwards" during use and is protected by the moulded housing.

[0050] In this sense, built-in guy wires reduced the physical space of the set and provided greater flexibility in the structure.

[0051] like Figure 10 As shown in the exploded view of FIG, the device 7 may comprise, in addition to the connecting shafts 27 and 28, optional additional construction details such as scrapers 24 and 25 and a guide bushing 26.

[0052] Having described examples of exemplary embodiments of the present invention, it should be understood that the scope of the present invention encompasses other possible variations of the described inventive concept, being limited only by the content of the accompanying claims, including the possible equivalents therein.

Claims

1. An electro-hydraulic disc brake comprising two pivotable vertical brake arms (2, 3), an upper brake arm (4) pivotally connected to one of the vertical brake arms (3) and a drive system formed by a release actuator (5), a spring brake device (6), an automatic brake pad wear adjustment and recovery device (7) located between the upper part of the other vertical brake arm (2) and the lower joint of the upper brake arm (4), characterized in that: The brake comprises a brake arm inter-connecting plate (14) having a brake arm positioning screw (15) and a brake opening clearance adjustment bushing (16), wherein the brake arm positioning screw (15) is a screw fixed with a calculated torque plate washer (16a), and wherein the brake opening clearance adjustment bushing (16) is disposed in a hole (14f) of the brake arm inter-connecting plate (14) to form a gap (F) between the brake opening clearance adjustment bushing (16) and the hole (14f); and The automatic brake pad wear adjustment and recovery device (7) comprises: a bearing (17) receiving a bushing (18) and a guy wire (19), at least a portion of an outer surface of the guy wire (19) and a portion of an inner surface of the bushing (18) having a multi-entry trapezoidal thread; a roller (23) disposed between the bushing (18) and the bearing, and a spring (21) disposed between the roller (23) and the bearing (17); The bearing (17) has an inner bore with a bevel (17f), and the bushing has a tapered end, the outer surface of which defines a corresponding bevel (18f), wherein the interaction between the bevel (18f) of the outer surface of the bushing (18) and the bevel (17f) of the bearing (17) allows free rotation of the bushing (18) when an axial force is applied in the direction of compression of the spring, and prevents rotation of the bushing when the axial force is applied in the opposite direction.

2. The electro-hydraulic disc brake according to claim 1, wherein: The bearing (17) forms a housing that receives the rear portion of the guy wire (19).

3. The electro-hydraulic disc brake according to claim 1 or 2, wherein: The multiple-input trapezoidal thread has a helix angle of approximately 32°.

4. The electro-hydraulic disc brake according to claim 1 or 2, wherein: The bearing (17) includes a body closed by a cover (22), and an inclined surface (17f) of the bearing (17) is formed on the cover (22).

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