Composite system and brake system powered by means of electric motor
The composite connection system with grooves and spherical elements addresses the challenges of preventing relative movements in electrically actuated braking systems, offering a stable, cost-effective, and easy-to-assemble solution with reduced noise and vibration.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- ROBERT BOSCH GMBH
- Filing Date
- 2025-12-15
- Publication Date
- 2026-06-25
AI Technical Summary
Existing connections in electrically actuated braking systems face challenges in preventing relative movements between components while requiring a simple, space-saving, and easy-to-produce design, often necessitating complex assembly processes and additional components like retaining rings and anti-rotation pins.
A composite connection system using grooves and spherical connecting elements with a screw mechanism to ensure backlash-free assembly, allowing for optimal force distribution and preventing axial and radial displacement, featuring a spring-loaded screw head for maintaining clamping and an anti-rotation fit.
The solution provides a stable, play-free connection with reduced noise, vibration, and harshness, simpler assembly, lower costs, and higher flexibility, while maintaining structural integrity and reducing the need for additional components like retaining rings and anti-rotation pins.
Smart Images
Figure EP2025087146_25062026_PF_FP_ABST
Abstract
Description
[0001] R.416862
[0002] - 1 -
[0003] Description
[0004] title and electrically operated
[0005] Description
[0006] State of the art
[0007] The connection of two components is of fundamental importance in many systems. In addition to the requirements for the strength of the connection, its implementation in production is particularly significant. Furthermore, it is necessary to consider which relative movements of the components should be prevented by the connection and to what extent.
[0008] Various concepts for electrically actuated braking systems (EMS) are known from the prior art. The principle of such braking systems is shown in Figure 6. The gearbox is the basic assembly that converts the relatively low torques of the electric motor, which engages via shaft 601, into the high torques required by the braking system to press the brake pads against the brake disc. As can be seen in Figure 6, the EMS comprises a two-stage gearbox. In the first stage 602, the worm gear 605 is driven via the worm shaft 606 shown in Figure 6. The reduction here occurs as a rotary input motion to a rotary output motion. The torque is transmitted via the worm gear adapter to the second gearbox stage 603, which is generally designed as a ball screw drive.In this second gear stage 603, the rotation induced by the electric motor is converted into a translational motion 604, in order to R.416862.
[0009] - 2 - to apply the (not shown) brake pads in the brake caliper to the disc brake (not shown).
[0010] Disclosure of the invention
[0011] The invention relates to a composite system comprising a first and a second unit. The first unit has at least one first groove extending radially along its outer surface, and the second unit has at least one second groove extending radially along its inner surface. The grooves are designed such that, in the connected state, the combination of the first and second grooves creates a cavity between the first and second units. A plurality of connecting elements are arranged in this cavity to counteract both axial and radial displacement of the first unit relative to the second unit.
[0012] The connection according to the invention results in a simple and space-saving connection that is easy to implement in production, as it requires only shallow grooves. Furthermore, the connection can be easily disassembled. Depending on the design of the connecting elements, the invention allows for backlash-free assembly and high flexibility in adjusting the relative position of the two units to be joined.
[0013] Further advantages of the compound according to the invention are listed at the end of the description.
[0014] In a particularly advantageous embodiment of the invention, the grooves are rounded, in particular semicircular, and the connecting elements are spherical. The spherical connecting elements within the cavity formed by these appropriately dimensioned grooves ensure optimal force distribution for the connecting forces.
[0015] The first unit and the second unit advantageously have rotationally symmetrical parts, with the first and second grooves extending in the region of these rotationally symmetrical parts. R.416862
[0016] - 3 -
[0017] In a particularly advantageous embodiment of the invention, at least the second unit is designed such that, in the connected state, an access to the cavity is formed. This allows for very simple insertion of the connecting elements after the two units have been joined at the rotationally symmetrical parts. For this purpose, the access should be dimensioned such that the connecting elements can be inserted into the cavity through the access.
[0018] The cavity may have a stop in the area of access against which the connecting elements arranged in the cavity abut.
[0019] A particular advantage is the provision of a device by which, in the connected state, the connecting elements arranged in the cavity can be pressed against the stop within the cavity. This ensures a particularly stable and play-free connection.
[0020] This device can be implemented by providing an internal thread for receiving a screw in the access opening. This screw allows the connecting elements to be pressed against the stop when the cavity is substantially filled with them. Specifically, a guide guides the screw through the second unit, ensuring at least partial positive engagement with both the first and second units.
[0021] In this case, it is particularly advantageous that the screw has a spring-loaded screw head.
[0022] The invention also relates to an electrically driven braking system described above, comprising a gearbox by means of which the rotary motion of an electric motor is converted into a linear motion for actuating a brake caliper. R.416862
[0023] - 4 -
[0024] The core of this invention consists in the fact that the housing containing the gearbox, as the first unit, and the brake caliper, as the second unit, form a composite system according to one of the preceding claims.
[0025] Further advantageous embodiments can be found in the dependent claims.
[0026] The following describes embodiments of the invention with reference to figures.
[0027] Figures 1 a, b and c show parts of the first and second unit.
[0028] Figure 2 schematically shows cross-sections of different connections.
[0029] Figures 3a, 3b, 4a, 4b and 5 show in cross-section various embodiments of the connection according to the invention with screw and stop.
[0030] Figure 6 shows the well-known principle of an electromechanical brake.
[0031] Figures 7a, 7b and 7c show different cross-sections of electromechanical brakes.
[0032] Embodiments of the invention
[0033] The invention relates to a combination of a first and a second unit.
[0034] Figure 1 shows
[0035] • in part a the part of unit 101 relevant for the compound according to the invention as well as
[0036] • in parts b and c, the part of unit 102 relevant to the compound according to the invention. R.416862
[0037] - 5 -
[0038] The parts of units 101 and 102 relevant for the connection according to the invention are rotationally symmetrical.
[0039] The part of the first unit 101 shown in Figure 1a has two radially extending grooves 101a and 101b on its outer surface. The part of the second unit 102 shown in Figures 1b and 1c has two radially extending grooves 102a and 102b on its inner surface. It should be noted that a single groove or more than two grooves can also be provided for the connection according to the invention.
[0040] The parts of the units shown in Figure 1a to 1c are dimensioned such that, when assembled, they form two cavities 103a and 103b (in Figure 3a) through the grooves. The rotationally symmetric part of the second unit 102 is guided over the rotationally symmetric part of the first unit 101.
[0041] Figure 1c also shows the access point 104 in the rotationally symmetrical part of the second unit 102. This access point 104 allows access from the outside to the grooves 102a and 102b, or, in the connected state, to the cavities 103a and 103b.
[0042] Figure 2 schematically shows in the left part the cross-section of a ball connection designed according to the invention and in the right part a connection with a retaining ring according to the prior art.
[0043] In both connections, parts 101 and 102 are joined.
[0044] This is achieved in the right part of Figure 2 by inserting a retaining ring 202a into a cavity 202b between parts 101 and 102. This retaining ring 202a is an annular component that is inserted into the cavity 202b to hold or secure parts 101 and 102 axially against the force F shown in Figure 2. R.416862
[0045] - 6 -
[0046] In the left part of Figure 2, spherical connecting elements 201a and 201b are shown in the cavities formed by the described grooves 101a, 101b, 102a and 102b.
[0047] As shown in Figure 2, both connections counteract a force F acting axially on parts 101 and 102. When using a retaining ring (right side of Figure 2), securing against torques acting around the axis is not possible with the retaining ring alone. For this purpose, an anti-rotation pin 707 (ARP) is required in addition to the retaining ring 202a, as shown in Figure 7, which will be described later.
[0048] By comparing the connection according to the invention, a ball connection in the embodiment shown, on the one hand, and a conventional connection using a retaining ring on the other hand, the advantages of a ball connection become clear:
[0049] • The ball joint allows for the greatest possible wall thickness of units 101 and 102 in the area of the connection, as no space 202b needs to be provided for the mounting of the retaining ring 202a.
[0050] • The ball connection results in better force redirection at the most stressed points of the connection, since the roundness of the balls 201 redirects the forces better than the sharp edge of a retaining ring 202a.
[0051] • With a ball joint, it is generally possible to disassemble the connection.
[0052] • In the production line, the ball joint means simpler assembly than a retaining ring 202a (circlip).
[0053] • According to the invention, “multi-row” connections (cavities) are also possible, since assembly is carried out tangentially to the connecting parts 101 and 102 through access 104. Two rows are shown, for example, in the left part of Figure 2. R.416862
[0054] - 7 -
[0055] • As will be shown in Figure 4, the connection according to the invention also prevents the components from rotating relative to each other. When using a retaining ring, an anti-rotation pin (ARP) 707 is required for this purpose, as shown in Figure 7c.
[0056] • Furthermore, in the connection according to the invention, a disc spring 706, as shown in figure 7c, is saved.
[0057] Figures 3a and 3b show further details in cross-section of an embodiment of the connection according to the invention.
[0058] Figure 3a shows a cross-section through a cavity 103, which is formed by the grooves 101a / b and 102a / b of units 101 and 102 in their assembled state. The connecting elements, designed as spheres 201, are inserted into the cavity 103 through the access point 104. Near the access point, the stop 105 can be seen, against which the first inserted sphere abuts.
[0059] Access 104 has an internal thread for receiving a screw 301. By means of this screw 301, in the case where the cavity 103 is substantially filled with the balls 201, the balls 201 can be pressed towards the stop 105.
[0060] Figure 3b shows the screw 301 in detail. The screw 301 has a spring-loaded screw head 301b due to the spring element 301a. This compensates for settling processes of the balls 201 in the cavity 103. As a result, the balls 201 remain tightly packed in the cavity even after they have been pressed against the stop 105 by the screw 301.
[0061] Figure 4 illustrates the clamping effect to avoid the aforementioned disc spring.
[0062] Figure 4a shows a cross-section of the ball joint on the right. Here too, the parts to be joined are labeled 101 and 102, and the balls are labeled 201. R.416862
[0063] - 8 - marked In the right part of Figure 4a, an axial displacement of part 101 relative to part 102 is shown schematically. It can also be seen in the load diagram that area 401 is the area subjected to the highest load during the axial displacement. This axial displacement is effectively counteracted when the balls 201 are pre-tensioned with the screw 301, as schematically shown in the left part of Figure 4a. This results in the balls 201 being wedged in the cavity. The spring-loaded screw head 301b, already mentioned with reference to Figure 3b, ensures that this clamping effect is maintained even if the balls 201 settle over time. Thus, by wedged the balls 201 in the cavity 103, an axial displacement of the two parts 101 and 102 is counteracted.
[0064] This clamping effect also affects the radial displacement between parts 101 and 102. This is illustrated in Figure 4b. On the right side of Figure 4b, this radial movement is labelled as torque M. If the balls 201 are not clamped in the cavity 103, radial displacement between parts 101 and 102 is possible in response to the torque M. If the balls 201 are clamped, as shown in the left part of Figure 4b, radial displacement between parts 101 and 102 in response to the torque M is effectively prevented.
[0065] Figure 5 shows another method for counteracting radial displacement of parts 101 and 102. Here, an embodiment is shown in which the second unit 102 is made of a softer material than the material of the first unit 101. This is the case, for example, when the connection according to the invention connects the power housing (gearbox housing) of an electric motor brake to a brake caliper. This will be described further with reference to Figure 7.
[0066] Figure 5 shows that the screw 301 is guided through the access point 104. The core of this embodiment is that the screw 301 is guided through the second unit 102 and has at least a partial positive fit with the first unit 101. This positive fit results in an "anti-rotation positive fit" 501, which prevents radial movement, i.e., relative rotation.
[0067] - 9 -
[0068] The displacement between units 101 and 102 around their common axis is effectively counteracted. This "anti-rotation effect" can be used either instead of, or in addition to, the jamming of the spheres as described in Figure 4b.
[0069] The principle of an electrically actuated braking system (EMB) shown in Figure 6 has already been described in the introductory section.
[0070] Figure 7a shows the connection according to the invention within an electrically actuated braking system (EMB). In comparison, Figures 7b and 7c show the same connection with a conventional retaining ring.
[0071] In Figures 7a, 7b, and 7c, the second unit 102 is designated by reference numeral 701. The first unit 101, designated by reference numeral 703, is the housing of the gearbox 704, the so-called power housing. Both the brake caliper 701 and the power housing 703 are rotationally symmetrical in the areas relevant for the connection and are dimensioned as described above such that a cavity is created in the connected state by the grooves already described. The balls 702, which act as connecting elements 201, have been inserted into this cavity. The cross-sections shown in Figures 7a and 7b do not explicitly show the EMB motor. In the section shown in Figure 7c, the motor is partially visible in the upper right part. The brake linings of the brake caliper 701 are designated by reference numeral 710.
[0072] Not shown in the section of Figure 7a is the access 104 to screw 301 .
[0073] This is shown schematically in Figure 5, where reference numeral 102 therein marks the brake caliper 701 and reference numeral 101 therein marks the power housing 703.
[0074] The clamping of the balls 201 / 702 in the cavity (Figure 4 / left part) as shown in the preceding figures and / or the “anti-rotational form fit” 501 (Figure 5) results in a connection between brake caliper 701 R.416862
[0075] - 10 - and power housing 703, which protects the two parts against both relative axial displacements and radial relative rotational movements.
[0076] To better understand the advantages of the connection according to the invention, the corresponding connection with a conventional retaining ring is shown in Figures 7b and 7c.
[0077] In a groove in the power housing 701, the retaining ring 705 (C-ring) is inserted into the cavity formed by the grooves of the power housing and the brake caliper when the power housing and the brake caliper 702 are assembled. The retaining ring 705 prevents axial relative movement between the power housing and the brake caliper when the two are connected. The disc spring 706 further restricts this axial relative movement.
[0078] To prevent radial (rotational) movement between these parts, the anti-rotation pin (ARP) 707, designated by reference numeral 707 in Figure 7c, is provided.
[0079] However, the connection with the retaining ring / C-ring 705 and the anti-rotation pin (ARP) 707 has the following disadvantages:
[0080] • The connection requires a complex assembly (high forces for the C-ring 705, orienting the C-ring, axially joining it, overcoming the spring force of the disc spring 706 and holding it in position under force until the "Automatic Ring Placer" (ARP) is pressed in), this is usually done by means of a fully automatic system.
[0081] • The correct seating of the C-ring 705 must be checked.
[0082] • Damage to the C-ring 705 may occur during singulation.
[0083] • The C-ring 705 must be coated for corrosion protection, and this corrosion protection must last the entire service life of the parts. This corrosion protection is particularly important for dynamically stressed components such as an EMB.
[0084] • Due to wear and tear during assembly, the assembly unit, the "Automatic Ring Placer" (ARP), needs to be replaced relatively frequently. R.416862
[0085] - 11 -
[0086] • The point of force application on the C-ring 705 and the disc spring 706 is off-center.
[0087] • The assembly unit, the "Automatic Ring Placer" (ARP), usually causes notches in the housing, which can reduce its strength.
[0088] • Due to the long tolerance chain in the alignment of the ARP during press-fitting, relatively large tolerances can occur in the connection.
[0089] • The necessary bore for the ARP in the brake caliper is critical with regard to strength.
[0090] In contrast, the described connection according to the invention with balls 201 and forming screw 301 has the following advantages:
[0091] • The backlash-free connection reduces NVH (Noise, Vibration, and Harshness) of the overall system, for example, when the power housing is connected to the brake caliper in an EMB (Electronic Brake Module). This means that unwanted noise, vibration, and harshness that can occur in braking systems are reduced.
[0092] • The connection according to the invention allows for a high degree of flexibility in the angular position of the parts to be joined.
[0093] • The connection according to the invention requires little installation space.
[0094] • Standard parts (balls, forming screws) can be used. The balls should be corrosion-resistant.
[0095] • The round indentation for access 104 results in a reduced notch effect on the housing.
[0096] • The connection according to the invention results in simpler assembly than with the described C-ring solution (force-free joining, adjusting the angle position compared to joining and screwing balls)
[0097] • The ball joint according to the invention can draw on the know-how of conventional ball bearings.
[0098] • The connection according to the invention allows for a higher wall thickness of the power housing compared to the C-ring solution.
[0099] • The costs of the ball connection according to the invention (costs for balls and forming screw) are significantly lower than those of a connection with a retaining ring (ARP, C-ring, disc spring). R.416862
[0100] - 12 -
[0101] Reference sign
[0102] • 101 : first unit (inner unit)
[0103] • 102: second unit (outer unit)
[0104] • 101 a: first groove running radially along the outer surface of the first unit
[0105] • 101 b: second groove running radially along the outer surface of the first unit
[0106] • 102a: first groove running radially along the inner surface of the second unit
[0107] • 102b: second groove running radially along the inner surface of the second unit
[0108] • 103a / b: cavities formed by combining the first and second grooves
[0109] • 201 a / b: Connecting elements
[0110] • 202a: Retaining ring
[0111] • 202b: Groove for retaining ring
[0112] • 104: Access
[0113] • 105: Stop
[0114] • 301 : Screw
[0115] • 301 a: spring element
[0116] • 301 b: Screw head
[0117] • 501: Anti-rotation form fit
[0118] • 601: Output shaft of the electric motor
[0119] • 602: first gear stage
[0120] • 603: second gear stage
[0121] • 604: Gearbox output
[0122] • 605: Worm gear
[0123] • 606: Worm shaft
[0124] • 701 : Brake caliper (102)
[0125] • 702: Connecting element (201 a / b)
[0126] • 703: Gearbox housing / power housing (102)
[0127] • 704: Gearbox
[0128] • 705: C-Ring
[0129] • 706: Belleville washer
[0130] • 707: Anti-Rotation Pin (ARP)
Claims
R.416862 - 13 - Claims 1. Compound system with a first and a second unit (101 , 102), wherein • the first unit (101) has at least one first groove (101a, 101b) extending radially on its outer surface and the second unit (102) has at least one second groove (102a, 102b) extending radially on its inner surface such that • in the connected state o by the combination of the first and second groove (101 a, 101 b, 102a, 102b) a cavity (103a, 103b) is created between at least parts of the first and second unit (101 , 102), and o in the cavity (103a, 103b) a plurality of connecting elements (201 a, 201 b) are arranged in such a way that both an axial and a radial displacement of the first relative to the second unit (101 , 102) is counteracted.
2. Composite system according to claim 1, characterized in that the grooves (101 a, 101 b, 102a, 102b) are rounded, in particular semicircular, and the connecting elements (201 a, 201 b) are spherical.
3. Composite system according to one of the preceding claims, characterized in that the first and second unit (101 , 102) have rotationally symmetric parts (101 , 102) and the first and second grooves (101 a, 101 b, 102a, 102b) extend in the area of the rotationally symmetric parts (101 , 102).
4. Composite system according to one of the preceding claims, characterized in that at least the second unit (102) is designed such that in the connected state (104) an access to the cavity (103a, 103b) is formed.
5. Composite system according to one of the preceding claims, characterized in that the access (104) is dimensioned such that the connecting elements (201 a, 201 b) can be supplied via the access (104) into the cavity (103a, 103b).
6. Composite system according to one of the preceding claims, characterized in that the cavity (103a, 103b) in the area of the access (104) has a stop (105) against which the connecting elements (201a, 201b) arranged in the cavity abut. R.416862 - 14 - 7. Composite system according to one of the preceding claims, characterized in that a device is provided by means of which, in the connected state, the connecting elements (201 a, 201 b) in the cavity (103a, 103b) are held against the stop (105) can be pressed.
8. Composite system according to claim 7, characterized in that the device is realized by the access (104) having an internal thread for receiving a screw (301), wherein the screw (301) presses the connecting elements (201 a, 201 b) in the direction towards the stop (105) when the cavity (103a, 103b) is substantially filled with the connecting elements (201 a, 201 b).
8. Composite system according to claim 7, characterized in that the screw (301) is guided through the second unit (102) by means of a guide and has at least a partial positive locking with both the first unit (101) and the second unit (102).
9. Composite system according to one of the preceding claims, characterized in that the screw (301) has a resilient screw head (301 b).
10. Electrically operated braking system with a gearbox (602, 603) by means of which the rotary motion of an electric motor is converted into a linear motion for actuating a brake caliper (701), characterized in that the housing (703) containing the gearbox forms a first unit and the brake caliper (701) forms a second unit, forming a composite system according to one of the preceding claims.