A SINGLE-PISTON AIR DISC BRAKE

Technical Field of the Invention

The present invention relates to a single-piston disc brake used in commercial vehicles and its comprised innovations. Using fewer parts than the number used in the prior art, the subject of the invention relates to the disc brake designed to reduce the complexity of the drive and adjustment mechanism in the closed volume of the caliper housing of the disc brake.

Prior Art

In patent files EP1852627A2, US10221907B2, EP343800A1 and

US2016/0215835A1, the caliper housing is connected to the carrier via guide pins. The caliper housing can slide on the guide pins and move in the axial direction. In this way, force can be exerted on the pads. Inside the caliper housing, there is a drive mechanism that can activate the brake by applying compressive force to one of the pads. The drive mechanism consists of one or more pistons, a lever and bearing elements that transmit the drive force to the piston by increasing it by variable rates. The half bearing, which transfers the forces from the lever to the caliper housing and allows the lever to rotate on an axis, the piston bushing, which carries the lateral loads from the thruster piston and allows the thruster piston to move on an axis, is used. There are one or more return springs separating the thruster piston from the pad when the driving force is reduced or terminated during the braking process. (Figure-23, Figure-24)

In the files EP1852627A2, US10221907B2, which have switched to the prior art, during the braking process, wear occurs on the pad and brake disc as long as the pads rub against the brake disc. This amount of wear occurs substantially on the friction surfaces of the pads. Thus, the operating gap between the brake disc and the pads increases over time. In this case, an automatic adjustment mechanism is used to ensure that the working gap is kept at a certain value in order to ensure that the braking performance does not decrease, and the desired braking moment is obtained and the brake activation time does not prolong. As the operating gap increases, the automatic adjustment mechanism allowing the pad to approach the disc by advancing the thruster piston is located inside the caliper housing, integrated into the piston shaft or just next to the drive mechanism. (Figure 25)

As in the file US10221907B2, the drive lever is seated by two half bearings in designs containing an automatic adjustment mechanism that operates integrated to the thruster piston. In these designs, a large and heavy pressure plate and at least two return springs are used. This increases the total weight of the brake. (Figure 22)

Patent file US10570970B2, which was introduced to the prior art, contains the inventions with a separate adjustment mechanism next to the piston. These adjustment mechanisms contain a large number of parts and they are in complex structures. In these techniques, the movement of the automatic adjustment mechanism is transmitted to the piston shaft with a gear or chain and the position of the thruster piston is automatically adjusted. In some techniques, the drive lever is seated with a half bearing and an additional bearing element. The geometry of the drive lever is complex and difficult to produce. Assembly labor and maintenance/service costs are high. (Figure-26)

The problems experienced in the above-mentioned files and in all known applications of the prior art are as follows:

1- Due to the bearing element, automatic adjustment mechanism parts, drive levers with complex geometries, production of these parts is difficult and costly.

2- The total weight of the brake is high due to the large number of parts that make up the brake mechanism.

3- Assembly and service costs are high due to the use of a large number of components. As a result, it has become compulsory to carry out R.&D studies on air disc brakes to eliminate the above-mentioned disadvantages and to develop solutions to existing problems.

Purpose of the invention

The total weight of the brake is important for vehicle manufacturers. For this reason, it is expected that brake manufacturers will optimize the structural parts of the brake in order to increase the braking capacity and increase the crosssection of the load-carrying parts by reducing the weight of the internal mechanism.

The weight of the internal mechanism parts has been substantially reduced by the present invention. This advantage has been made possible by the design of a simpler automatic adjustment mechanism. Instead of a complex and difficult to manufacture drive lever, a lightweight drive lever with simple geometry and easier to manufacture is designed. Thus, it has been ensured that the brake is less costly and easier to manufacture and maintain.

The brake performance expected by vehicle manufacturers can be met by a lighter disc brake. Both driver comfort, environmental and economic positive effects of this cannot be ignored.

Detailed Description of the Invention

In order to understand the innovations made in order to achieve the above- mentioned purposes in a single-piston air disc brake subject to the invention in the best way, it should be evaluated in the light of the following figures.

Among these figures;

Figure - 1 Overall perspective view of the disc brake

Figure - 2 Overall perspective view of the disc brake from different angles

Figure - 3 Interior detail perspective view of complete disc brake Figure - 4 Interior detail view of disc brake caliper housing

Figure - 5 Caliper rear view of disc brake interior detail

Figure - 6 Disc brake cross-sectional view

Figure - 7 Interior detail perspective view of disc brake caliper housing

Figure - 8 Brake drive mechanism perspective view

Figure - 9 Exploded view of brake drive mechanism

Figure - 10 Exploded view of brake automatic adjustment mechanism

Figure - 11 Disc brake cross-sectional view

Figure - 12 Exploded view of the design of the second type adjustment mechanism

Figure - 13 Perspective view of second type of pressure plate

Figure - 14 Cross-sectional view of caliper housing

Figure - 15 Cross-sectional view of the design of the second type adjustment mechanism

Figure - 16 View of the second type of brake pad and piston fixing channels on it

Figure - 17 Exploded view of the second type of drive and adjustment mechanism

Figure - 18 Perspective view of driving lever

Figure - 19 Front view of drive lever

Figure - 20 Cross-sectional view of drive lever

Figure - 21 Perspective view of the caliper cover

Figure - 22 Single piston disc brake view with a double seated lever relating to US10221907B2

Figure - 23 Single piston disc brake view with a dual-seated lever and a multi-plate clutch adjustment mechanism relating to EP3431800A1

Figure - 24 Single piston disc brake view with single seated lever and multi-plate adjustment mechanism relating to US2016/0215835A1 Figure - 25 Disc brake view with a separate adjustment mechanism from the piston containing a curved lever with large and small bearing relating to EP1852627A2

Figure - 26 Single piston disc brake view with a separate adjustment mechanism from the piston relating to US10570970B2

In order to understand the innovations made in a single-piston air disc brake subject to the invention in the best way,, numbers are placed on the pictures. Accordingly;

1. Carrier

1.1. Guide pins

2. Caliper Housing

2.1. Piston support

2.2. Tooth locked washer channel

3. Pads

3.1. Piston retaining channels

4. Brake disc

5. Thrust piston

5.1. Piston retaining projections

6. Drive lever

6.1. Connection area

6.2. Bearing channel

6.3. Lever arms

6.4. Pin housing

6.5. Hollow

6.6. Roller housing

6.7. Air chamber push-rod pocket

7. Half bearing

8. Piston bushing

9. Return spring

10. Manual adjustment mechanism

11. Automatic adjustment mechanism

11.1. Adjustment fork

11.2. Wrap spring 11.3. Adjustment ring

11.4. Piston shaft

11.5. Spring washers

11.6. Circlip

11.7. Cone clutch

12. Caliper cover

12.1. Bearing seat surface

12.2. Bearing tooth seat

13. Pressure plate

13.1. Roller pressure surface

13.2. Step

14. Tooth locked washer

14.1. Tooth

15. Washer

16. Driving gear

16.1. Tooth locked washer contact surface

17. Seal

18. Ball-endedpin

19. Roller

20. Roller bushing

21. Second type automatic adjustment mechanism

21.1. Second type adjustment fork

21.2. Second type wrap spring

21.3. Second type adjustment ring

21.4. Second type piston shaft

21.5. Spiral pressure spring

21.6. Pressure washer

21.7. Thrust bearing

21.8. Second type circlip

21.9. Second type cone clutch

22. Second type pressure plate

22.1. Roller pressure surface

22.2. Step a. Elongation angle b. Arm width c. Arm depth d. Hollow width e. Hollow length f. Hollow depth

The air disc brake has a carrier (1). Duty of the carrier is to hold the pins (1.1) guiding to the caliper housing (2). There is a brake disc (4) in the space in the middle of the carrier and pads (3) are placed on both sides of the brake disc (4). Another duty of the carrier is to carry the braking forces caused by the friction of the pads (3) on the brake disc (4). (Figure-1, Figure-2)

The invention in question has a thruster piston (5) in the caliper housing (2), an automatic adjustment mechanism (11) operating on the same axis as the piston shaft and integrated on it, a drive lever (6), a half bearing (7) operating with drive lever (6), and a return spring (9). There is also a manual adjustment mechanism (10) that provides motion transmission through a gear. The pressure plate (13) used for transmitting the drive force from the drive lever (6) to the piston shaft (11.4) in the caliper housing (2) of the invention is thin and lightweight. The force transmission line used in the invention is on a straight line. (Figure-6, Figure-7) Thus, a thin pressure plate (13) can be used. The roller housing (6.6) on the drive lever (6) includes the roller bushing (20). The roller (19) can rotate in the roller bushing (20). The pressure plate (13) has a flat roller contact surface (13.1) in contact with the roller (19). There is a quadrilateral or circular step (13.2) surrounding the roller contact surface (13.1). This step (13.2) prevents the roller (19) on the drive lever (6) from moving axially and falling out from its seat. (Figure-3, Figure-4, Figure-6, Figure-17)

The main innovation of the invention is the use of a drive lever (6) which has been manufactured by forging or casting method and machined with the bearing channel (6.2) in order to be used with the half bearing (7) used as bearing element. The drive forces acting on the drive lever (6) shown in Figure 18 and the stress level generated by these forces on the drive lever (6) are calculated. According to the engineering calculations, the cross-sectional dimensions of the lever arms (6.3), have been determined as arm width (b) between 7.5 - 9.5 mm and arm depth (c) between 18.5 - 21.5 mm. Thus, the drive lever (6) is prevented from cracking and breaking from the arms specified under repeated loads during the economic life of the vehicle. In addition, an optimization between the lever mass and strength has been achieved by determining the hollow length (e) of the hollow (6.5) in the lower part of the roller housing (6.6) as 23 - 25 mm, the hollow width (d) as 11 - 13 mm and the hollow depth (f) as 9.5 - 10.5 mm in order to lighten the drive lever (6). (Figure - 20) The ball- ended pin (18) is connected to the pin housing(6.4) formed at one end of the roller housing (6.6). The connection area (6.1) between the air chamber pushrod pocket (6.7) and the lever arms (6.3) of the drive lever (6) is designed such that a certain angle of extension (a) is between 38 and 42 degrees to prevent stress build-up. (Figure-19) In this way, the drive lever (6) is lighter, and the production and machining costs are lower than the prior art. (Figure 5)

Another innovation is the use of a tooth locked washer (14) that is located between the return spring (9) and the driving gear (16) and contacts these two parts. The washer (15) contacts the other side of the return spring (9) and the washer (15) and return spring (9) are located over the piston bushing (8). The tooth locked washer (14) has been designed with a tooth form. Tooth (14.1) on the tooth locked washer (14) is placed into tooth locked washer channel (2.2) on caliper housing (2) during assembly and rotation movement of locked washer (14) is prevented. (Figure - 14) However, when the thruster piston (5) is moved in the braking direction, the tooth (14.1) of tooth locked washer (14) is able to perform axial movement within the tooth locked washer channel (2.2) Meanwhile, when the automatic adjustment mechanism (11) is adjusting, the tooth locked washer (14) does not rotate while the driving gear (16) rotates counter-clockwise. Thus, no energy is stored on the return spring (9) in the direction of rotation. (Figure-8, Figure-9) If energy is stored on the return spring (9) in the direction of rotation , when braking is terminated, the driving gear (16) rotates clockwise with the return spring (9) and de-adjusts the operating clearance. Thus, the gap between pad (3) and brake disc (4) increases and braking performance reduces. Tooth locked washer (14) prevents energy storage by shape change of the return spring (9) in rotation direction and generates a friction force as it contacts with driving gear (16). The friction force between the tooth locked washer (14) and driving gear (16) is designated by engineering calculations. (Figure - 14) In this way, the cone clutch (11.7) in the automatic adjustment mechanism (11) can rotate the piston shaft (11.4) and the driving gear (16) while activation of the brake and adjust the operating clearance. Pressure force is transmitted to the cone clutch (11.7) by spring washers (11.5). A circlip (11.6) is connected to one end of the spring washer (11.5). When braking is finished, the wrap spring (11.2) terminates the clutch function, allowing the adjustment ring (11.3) to return independently of the piston shaft (11.4). The piston shaft (11.4) does not rotate in the opposite direction and prevents the operating gap from increasing. If the friction force on the contact surface (16.1) between the tooth locked washer (14) and the driving gear (16) is high, the clutch moment of the cone clutch (11.7) is insufficient during braking. The cone clutch (11.7) slips and the adjustment cannot take place. If the friction between the tooth locked washer (14) and the driving gear (16) is insufficient, the piston shaft (11.4) rotates in the opposite direction in the brake release phase and an de-adjustment occurs. All these equilibrium on the automatic adjustment mechanism (11) could be achieved by engineering calculations.

Another innovation of the invention is that the force transfer from the drive lever (6) to the piston shaft (11.4) can be performed using a much lighter and thinner pressure plate (13) than the prior art. The roller pressure surface (13.1) of the pressure plate (13) is designed flat. Thus, the lateral loads caused by the eccentric movement of the drive lever (6) are reduced and the brake efficiency is increased. There is also a step (13.2) around the roller pressure surface (13.1). This step (13.2) can be circular or slot (22.2). The purpose of using the step (13.2) is to prevent the roller (19) from separating from the drive lever (6) due to forces caused by gravity or vibration. If the roller (19) is separated from the drive lever (6) and falls into the caliper housing (2), the braking is eliminated and causes accidents. Therefore, step (13.2) is of great importance.

The second type automatic adjustment mechanism (21) shown in Figure 17 is connected to the second type pressure plate (22). The second type pressure plate (22) has a roller pressure surface (22.1) in contact with the roller (19) and a step (22.2) formed on both sides of the second type pressure plate (22). (Figure - 13) The width of the step (22.2) is between 38 - 40 mm and its length is between 8-18 mm by engineering calculations.

Another innovation of the invention is that the bearing seat surface (12.1) shown in Figure 21 and the bearing seat surface (12.1) used for bearing have two bearing tooth locked washer housings (12.2) at the bottom and above. Thanks to this feature, the half bearing (7), which serves as a bearing, is prevented from losing its function by leaving the housing with the effect of vibration forces and gravity by preventing the axial movement from the bearing seat surface (12.1). In addition, an easy-to-machining, low-cost caliper cover (12) is used due to its single bearing feature on the bearing seat surface (12.1).

Another innovation criterion of the invention is the presence of piston support (2.1) within the caliper housing (2). (Figure - 11) It is positioned under the adjustment fork (11.1) for carrying the vertical forces from the drive lever (6). The adjustment fork (11.1) is designed in the form of a projection measured in the same radius as the outer radius. Thanks to this feature of the adjustment fork (11.1), the loads on the piston bushing (8) are reduced. Thus, the service life of the piston bushing (8) is extended. It also increases braking efficiency. Since both the linear movement and the rotational movement of the adjustment fork (11.1) are guided by this piston support (2.1), the piston support (2.1) is designed by evaluating engineering analyses and friction calculations.

Another mode of application of the automatic adjustment mechanism (11) is the use of a larger diameter second type cone clutch (21.9), helix pressure spring (21.5), thrust bearing (21.7), which is the second type automatic adjustment mechanism (21). Due to production tolerances, different forces can be obtained in the same amount of compression in spring washers (11.5). This may cause each mechanism to have different efficiency and different characteristics. This is an undesirable case. Thanks to the helix pressure spring (21.5), the size of the pressure force applied to the second type of cone clutch (21.9) is more stable compared to the use of spring washer (11.5). The effect of the force variability in the second type of cone clutch (21.9) with large diameter (40-45 mm) and small clutch angle (1-5 degrees) can be kept to a minimum. The contact between the second type piston shaft (21.4) and the second type adjustment ring (21.3) is interrupted by the position where the spiral pressure spring (21.5) is located. Therefore, the efficiency of the second type automatic adjustment mechanism (21) and indirectly the brake efficiency has been increased and the wear problems that may be seen in the second type piston shaft (21.4) and the second type adjustment ring (21.3) have been eliminated over time. In addition, thanks to the thrust bearing (21.7) positioned between the spiral pressure spring (21.5) and the second type piston shaft (21.4), the friction force that negatively affects the brake adjustment performance is also minimized. The pressure washer (21.6) is positioned between the spiral pressure spring (21.5) and the thrust bearing (21.7). When braking is finished, the second type wrap spring

(21.2) terminates the clutch function, allowing the second type adjustment ring

(21.3) to return independently of the second type piston shaft (21.4). However, the second type of cone clutch (21.9) design with a cone diameter in the range of 40-45 mm and a cone angle in the range of 1-5 degrees, the wear problem that can be observed over time in the second type adjustment ring (21.3) and the second type adjustment fork (21.1) is minimized. Thus, the second type of cone clutch (21.9), the second type of adjustment ring (21.3) and the second type of adjustment fork (21.1) have a longer life. The second type circlip (21.8) is connected to the end of the second type adjustment fork (21.1). In addition, due to the large diameter of the second type of cone clutch (21.9) (40-45 mm), the adjustment efficiency is also increased as the compressive force required for the clutch is reduced. (Figure-12, Figure 15)

Unlike the present technique, a piston fixing method has been applied in the invention. There are retaining projections (5.1) on the thrust piston (5) and the thrust piston (5). On the back of the pad (3) there are slot and/or channelshaped piston fixing channels (3.1) shown in Figure-16, where the retaining projections (5.1) are seated and preventing the rotational movement of the thruster piston (5). Seal (17) is placed so that it comes into contact with piston retaining projections (5.1). Piston fixing projections (5.1) and piston fixing channels (3.1) are designed by measuring the maximum manual adjustment moments and by calculating the strength of the parts to prevent damage to the parts in case of excessive moment application.