Field of the Invention

This invention refers to an automatic slack adjuster brake between the wear element and the rotating element of an automotive braking system whose slack adjustment system is based on the false rotation of the coupling of the slack set over the traction coupling, when there is excessive slack resulting from the wear of the pad, and its locking is processed by means of dentate surfaces, which promote the adjustment of the set to a slack deemed acceptable. Background of the Invention

Automotive braking systems, especially those for heavy vehicles, such as trucks and buses, promote the contact between the surface of an rotating element associated with the wheels, usually a drum or disc, and a wear element, pads or discs, which have attrition with each other, causing the reduction of the rotation speed of the rotating element and, consequently, of the vehicle.

As a result of use, the wear elements have their thickness reduced throughout time, causing a substantial increase of the space between their surface of contact and the surface of contact of the rotating element, demanding an adjustment of this slack in order to allow the due functioning of the system as a whole.

This adjustment can be made manually, through the use of devices such as bolts, switches, and couplings, with the regulation of the slack to a level deemed appropriate. Automatic brake adjusters on their turn are capable of detecting an excessive route for the brake actuator, due to additional wear of the brake pads, and of automatically gauging such route to maintain the proper space between the parts. The intention is to allow, after wear of the pads above a certain limit, the automatic adjuster to promote the dislocation of the pad towards the attrition surface, thus reducing the space between surfaces and consequently the route of the brake actuation mechanism when braking. In the current state-of-the-art, related to automatic adjusters, the mechanism of the adjusters is based on the perception of excessive slack caused by the wear of the wear elements, as to promote a correction of the route of the brake actuator to compensate such slack. The perception of excessive slack is possible through the use of mechanical systems associated with the angular movement of the slack adjuster set. Thus, when the angular movement occurs beyond the limit of the elastic slack and of the normal slack between the components, the adjustment system promotes the dislocation of the brake actuator coupling to an advanced point in relation to its route.

The adjustment system can be composed by arrangements based on coupling by friction or, more contemporary, based on the coupling of spur gears that promote the carriage of the set and the dislocation of the brake actuator coupling.

By rule, the coupling of the gears is promoted by means of grooves coinciding in opposed surfaces that interact, forming a set of reentries and crimped overhangs. The recurring inconvenience is that after successive actuations, the gear coupling system naturally undergoes wear. This invention solves such problem by replacing the coinciding grooves by two coinciding spur surfaces that adjust in the top position, sensibly reducing wear. State of Art Analysis Patent PI 9711883-4 describes a brake adjuster by friction that consists of an extended fixation device with first and second ends. The fixation device is arranged in a hole of the brake piston, movable in relation to a brake housing that surrounding the friction brake for a braking position and for a retracted position of the brake piston, which may be dislocated to the T/BR2010/000088

retracted position by means of a flexible element. The patent deals with a friction brake adjuster and does not mention spur surfaces or command stem, therefore, different from the present invention.

Document PI 8603432-4 deals with an automatic adjuster that works to keep a constant slack between the braking surfaces, respectively, of the braking element and the rotating braking element of a braking system that operates in a rotating system and, therefore, not applicable to the characteristics of the invention. Invention PI 82045800-1 demonstrates an automatic adjuster, detector of slack and disc brake actuation set, whose means are movable brake actuators, a rotating propeller element, a rotating propelled element, and a positive clutch, usually geared, providing a driving connection between the propelled element and the rotating adjustment element, not applicable to the characteristics of the invention, as it only describes rotating actuating elements.

Document US 3999638 deals with the brake slack adjusters, not applicable to the characteristics of the object of analysis, for it only describes manual actuators that work based on screw nuts. Patent US6408993B1 reveals an arrangement of control for brake lever coupled to an "S" chamber axis with groove, of an automotive braking system with drums, connected to a stem of cylindrical compression. Although the document mentions a control disc, it is different from the invention for it does not present the spur interface that is adjusted and locked when placed on the top. Invention US7198138B2 describes an automotive braking system that automatically adjusts the slack developed as a result of the pads and drum. When the angular movement of the housing lever exceeds the desired limit due to wear, the internal device automatically adjusts the excessive slack. It 00088

is different from the invention for it does not present the same spur surface of adjustment and lock.

Patent WO 2007/023508A1 deals with an automatic brake adjuster with a flexible reference point in which an one-way locking device and a clutching device are integrated in a part and placed in a worm shaft to isolate the locking mechanism and the gear of regulation of the clutch spring loaded by the pressure glove to work independently. The locking mechanism works as a sensor of the excess of slack of the pad and to adjust the slack between the pad and the drum where the clutching mechanism is located, ignoring the excessive travel of the brake actuator due to the elasticity in the parts of the brake of an automotive braking system. It is different from the invention proposed, for it does not present spur interface that is adjusted and locked when placed on top. Document MU 8100426-5 reveals a brake adjuster whose working system is similar to that of this invention, but using the coupling connection with a screw nut, both provided by the respective coupling. Therefore, it promotes a different connection system, more complex and requiring a larger number of parts for its composition. Description of Figures Figure 1 shows an exploded view of the automatic break adjuster, evidencing its components and parts, with special highlight to the following: frame (1); command stem (2), which, in its linear movement, moves the slack set gear (12); fork (3), which moves the adjuster and tractions the command stem (2), with variations of dislocation (3A); scrapper (4), dust coat (5), sealing cap (7), and sealing rings (20 and 25) ensure that the internal lubrication of the adjuster is not subject to leakage during its operation and protect the adjuster against dust; sprocket (6) and worm shaft (11) transmit the load from the frame (1) to the shaft, with the sprocket teeth (6) being asymmetrical; the front lid (8) seals the regulating set and supports the work of the cover (16); the dust coat bushing (10) guides the command stem (2) and supports the mount of the scrapper (4) and dust coat (5); the slack set gear (12) pulled by the command stem (2) determines the slack between the pad and the drum, in addition to pulling the coupling set (13 and 14); the traction coupling (13) and the slack set coupling (14) pull, when necessary, the worm shaft (11) through saw teeth, considering that such worm shaft (11) is fitted into the interior of the traction coupling (13) and is attached by a lock ring (24); the bearing (15) is attached by the bolt (22), supporting the worm shaft (11) and the compression spring (19); the cover (16) releases the contact between the saw teeth of the couplings (13 and 14), according to the adopted setting; the locking bushing (17) ensures that the worm shaft (11) remains steady during the rotation of the slack set coupling (14) over the traction coupling (13); the compression spring (18) maintains constant pressure to the contact between the locking bushing (17) and the worm shaft (11); the expansive plate (21) regulates the pressure to be exercised by the compression spring (18); the bushing (26) is a disposable part, destined to protect the frame (1) of wear due to attrition; the grease box (23) is the lubrication point of the set, and it may be either straight or angular, and attached to various points of the adjuster; pins (9 and 27), mounted in the fork (3 or 3A) are attached by means of counter-pins (28 and 29) and promote the traction of the frame (1) and the command stem (2) upon the actuation of the set. Figure 2A illustrates the manner how the set is moved upon the braking actuation, indicating, in the arrows, the direction of the movement of the set and the consequent traction exercised by the command stem (2). Figure 2B details the interaction between the gear of the slack set (12) and the command stem (2).

Figure 3A illustrates the angles of actuation of the adjuster: angle "A" corresponds to the normal slack, in which the adjuster works without promoting the dislocation of the gears; angle "B" corresponds to the elastic slack, due to the elasticity of the components upon the braking load, and angle "C" corresponds to excessive slack between the pad and the drum, based on which the adjuster promotes the correction of the slack between the parts. Figure 3B illustrates angle "D", correspondent to the reflex of angle "A" in the set of the adjuster parts. Figure 3C illustrates the detail of angle "D" in the interaction of the command stem (2) with the slack set gear (12) and with the slack set coupling (14). Figure 4A illustrates the movement of the adjuster during slack angle "A", where the adjuster moves and causes the fork (3) to pull the command stem (2), transforming its linear movement into rotation of the slack set gear (12), touching the right flank of the slack set coupling (14), while the worm shaft (11) remains steady with the support of the locking bushing (17). Figure 4B details the movement of the command stem (2) upon the actuation of the adjuster, where it is possible to observe the aligned position of teeth 1, 2, and 3 of the coupling set (13 and 14).

Figure 5A shows a cross-section view of the interaction of the command stem (2) with the slack set gear (12), during the movement upon the adjuster actuation. Figure 5B details the cross section view, elucidating the traction of the command stem (2) over the slack set gear (12).

Figure 6A illustrates the movement of the adjuster during elastic angle "B", in which the slack set gear (12) pulls the slack set coupling (14), as to make it slide on the traction coupling (13). Figure 6B details the interaction of the command stem (2) movement with the slack set gear (12) during angular dislocation "B", in which the slack set coupling (14) slides over the traction coupling (13), evidencing the distancing of teeth 1, 2, and 3, previously aligned.

Figure 7A represents the movement of the adjuster during slack angle "C", in which the excessive wear of the wear element causes the exceeding of angle "B", causing the slack set coupling (14) to slide over the traction coupling (13), surpassing the spacing between the teeth and promoting the insertion into a point that is advanced in relation to the teeth fittings. Figure 7B illustrates the insertion of the slack set coupling (14) with the traction coupling (13) in an advanced position, when teeth 1, 2, and 3 are positioned advanced in relation to the previous alignment.

Figure 8A presents the movement of the adjuster return after excess angle "C", in which the fork (3) pushes the command stem (2) that pulls the slack set gear (12) in the opposite direction, until it touches the superior flank of the traction coupling (14). Figure 8B details the movement of the command stem (2) over the slack set gear (12) upon the adjuster actuation. Figure 8C illustrates the insertion of the slack set coupling (14) with the traction coupling (13) in advanced position, during the movement of return. Figure 9 illustrates the movement of return of the adjuster during angles "B" and "A", in which the traction coupling (13) pulls the worm shaft (11), whose conical teeth push the locking busing (17), dislocating it axially. Throughout this movement of return, the worm shaft (11) also the sprocket (6) and consequently the axis inserted therein. Figure 10 illustrates the adjuster after the return to its original position, already with slack between the pad and the drum, automatically corrected to acceptable levels. Detailed description of the Invention

This invention refers to an automatic slack adjuster between a wear element (such as brake pads) and a rotating element associated with the wheel motion, such as the brake drum of automotive braking systems, considering that the adjustment promoted by the automatic adjuster is based on the false rotation of the slack set coupling (14) over the traction coupling (13), when there is excessive slack, usually caused due to wear of the pads. The set interacts as to promote the locking, through spur surfaces, generating traction sufficient in the set to provide the adjustment of the space between the pad and the drum to a slack deemed acceptable.

It regards to a functional advance in relation to invention MU8100426-5, already validated by the National Institute of Industrial Property ("INPI"), which foresaw the connection of the coupling against a screw nut, both provided with the respective fittings. Such connection system is more complex and requires more parts in its composition, which is being treated more simply and directly by the present invention, by promoting the interaction between the slack set coupling (14) and the traction coupling (13).

The invention consists of a frame (1), preferably of nodular cast iron, which promotes resistance and elasticity, and it can be provided in various lengths and inclinations, pursuant to the configuration of the vehicle, whose objective is to provide support for the functioning of the slack adjustment function, comprising various components. The command stem (2) dislocates following a linear movement, interacting and moving the slack set gear (12). The Fork (3 or 3A) moves the adjuster when the brake is triggered, at the same time in which it pulls the command stem (2), and it can be provided with various dislocation lengths, according to the use. The scrapper (4), dust case (5), sealing cap (7), and sealing rings (20 and 25) ensure that the internal lubrication of the adjuster is not subject to leakage during its actuation, and protect the adjuster against undesired elements, such as water, dirt, dust, etc. The sprocket (6) and the worm shaft (11) transmit the load of the frame (1) to the "S" camshaft, considering that the teeth of the sprocket are asymmetrical and preferably, both parts are made of high quality stainless steel, which ensures mechanical resistance after receiving the proper thermal treatment. The front cover (8) seals the adjustment set as a whole and provides work support to the cover (16). The dust case bushing (10) guides the command stem (2) and supports the mount of the scrapper (4) and dust case (5). The slack set gear (12), pulled by the command stem (2) determines that the slack between the wear element and the rotating element, in addition to pulling the coupling set (13 and 14). The traction coupling (13) and the slack set coupling (14) pull, through saw teeth, when necessary, the worm shaft (11). The traction coupling (13) has an internal fitting, preferably six-headed, where the worm shaft (11) is coupled. The locking ring (24) guarantees the traction capacity of the coupling (13), making it a single piece with the worm shaft (11). The bearing (15), attached by bolt (22), supports the worm shaft (11) and also the compression spring (19). The cover (16) releases the contact between the saw teeth of the couplings (13 and 14) upon the adjustment of the automatic adjuster. The locking bushing (17) guarantees that the worm shaft (11) remains steady during the rotation of the slack set coupling (14) over the saw teeth, upon its dislocation over the traction coupling (13). The compression spring (18) maintains constant pressure so that the contact of the locking bushing (17) with the worm shaft (11) is permanent. The compression spring (18) has its pressure regulated by means of the expansive plate (21). The bushing (26), preferably made of tempered steel, protects the frame (1) against wear, and may be replaced when needed, having different diameters, depending on the need. The grease box (23) is the lubrication point of the adjuster mechanism, and it may be either straight or angular, and attached to various points of the adjuster. Pins (9 and 27), mounted in the fork (3 or 3A) are attached by means of counter- pins (28 and 29) and promote the traction of the frame (1) of the adjuster and the command stem (2).

Once the automatic adjuster is installed in the vehicle, the command stem (2) will be in its starting point, positioning the slack set gear (12) in contact with the upper flank of the slack set coupling (14). The existing slack (angle "D") between the parts (12 and 14) is compatible with a slack deemed acceptable between the pad and the brake drum, respective, the elements of wear and elements of rotation of the braking system. During the movement of the automatic adjusted in angle "A", the device moves and causes the fork (3) to pull the command stem (2), transforming its linear movement into rotation, turning the slack set gear (12) until it touches the lower flank of the slack set coupling (14). During this movement, the worm shaft (11) remains steady with the support of the locking bushing (17). The brake wedges expand by just touching the brake drum. From this movement, the gear (12) now rotates the coupling (14), causing it to slide over the teeth of the traction coupling (13). The braking load is exercised as a whole during movement "B", so that the area of contact between the teeth of the parts (14 and 13) is sufficient to guarantee a good braking of the vehicle without any adjustment. The representation of angle "C" reflects what happens upon the excessive wear of the braking pads, from the movement of angle "B", i.e., angle "B" in excess.

The coupling (14) has its rotation beyond the point of insertion of the teeth, where it slides over the next tooth of the traction coupling (13). At this moment, the fork (3) begins to push the command stem (2) that rotates the slack set gear (12) in the opposite direction, until it touches the upper flank of the traction coupling (14). The traction coupling (14) begins to rotate the worm shaft (11). At this moment, the conical teeth of the worm shaft (11) push the locking bushing (17), which slides axially. During the movement of return, the work shaft (11) remains spinning, thus rotating the sprocket (6) and also the "S" camshaft.

After returning to the initial position, the result is an automatic adjustment, maintaining as constant the slack between the pads and drum. If the slack is excessively large, for instance, after the adjuster has been removed for maintenance, the brake will have to be actuated several times to regulate 00088

the route of the automatic brake adjuster. The work cycle, in this case, is the same described above, with the following differences: when the brake is applied with normal slack, the automatic brake adjuster will act many times as described above. When the brake is released, the automatic break adjuster returns to the initial position without any adjustment, working in this way until the pad is worn out, when it will then start to perform its function.

This invention is not limited to the representations commented or illustrated herein, and must be understood in its broad scope. Many changes and other representations of invention will come to the mind of those acquainted with the technique related to this invention, with the benefit of the lessons learned from the descriptions above and attached drawings. Furthermore, it should be understood that the invention is not limited to the specific form revealed, and that changes and other forms are understood as included within the scope of the claims attached hereto. Although specific terminology is employed in this document, these terms should be used only in the generic and descriptive forms, therefore not limitative.