A braking simulator device with conical spring washers

Abstract

The present invention relates to a braking simulator device (1000) with conical spring washers, comprising a cylindrical casing (100) configured for the internal sliding of a floating element (200), wherein the floating element is axially pushed by a coil spring (300) which pushes, on one side, on one end of the floating element (200) and, on the other side, on a shock absorber pin (400), wherein said end of the floating element (200) has a tip (250) which penetrates into the coil spring and is configured to abut against an element of the shock absorber pin (400), the device (1000) being characterized in that : a first plurality of conical spring washers (500) is arranged axially in series between said shock absorber pin (400) and said shock absorber ring (600); a second plurality of conical spring washers (700) is arranged axially in series between said shock absorber ring (600) and said final absorber element (900); wherein said shock absorber pin (400) is provided with a shock absorber pin tip (450) configured to abut against said shock absorber pin after a first predetermined axial stroke, and wherein said shock absorber ring (600) is provided with a shock absorber ring tip (650) configured to abut against said final absorber element (900) after a second predetermined axial stroke.

Description

[0001] A braking simulator device with conical spring washers

[0002] To: Brembo N.V.

[0003] Inventors: Martina Truffello, Manlio Della Rossa

[0004] The present invention relates to a brake pedal simulator device with conical spring washers.

[0005] Background art

[0006] The context relates to the use of a brake pedal simulator (eBPS) in a braking system, which decouples the control input from the hydraulic output pressure. In systems of this type, a force resisting the imposed pedal pressing is generated to provide a feedback to the user.

[0007] At present, braking systems in which the command is hydraulically and mechanically decoupled from the actuation are provided with a pedal pressing simulator, which returns a force feedback which resists the pressing by the user on the input command. For safety reasons, it is necessary to use an eBPS simulator which associates a reaction force with the command stroke. This force feedback is usually generated by a system of coil springs with different characteristic stiffnesses, actuated in series and / or in parallel to generate a non-linear resistance curve. Specifically, a progressive resistance curve is necessary to simulate the feeling returned by a conventional hydraulic system.

[0008] Figure 1 shows an example of an eBPS assembly with coil springs actuated in sequence or in parallel to obtain a progressive stiffness curve.

[0009] United States Patent US 2021 / 0291797 Al describes a pedal force simulator device which includes a pressure piston actuatable by a brake pedal and axially mounted in a housing. The device has at least two stacks of conical spring washers connected in series, each with at least two conical spring washers, and at least two of these stacks have different elastic constants. These stacks are located in the housing between an end face of the pressure piston and an axial stop of the housing. At least one of the stacks of conical spring washers includes an axial receiving recess, in which an elastic element, which can be deformed by the pressure piston, is located. One end of the elastic element is supported on the pressure piston and the other end is supported on one of the stacks of conical spring washers.

[0010] The context of this invention is the attempt to simulate the pedal force feeling perceived during the actuation of a conventional hydraulic braking system. The device generates a restoring force on the brake pedal when the latter is actuated.

[0011] The inherent problems and limitations of pre-existing pedal simulation systems include several drawbacks related to the use of coil springs:

[0012] - Low stiffness and large size: The coil springs are characterized by low stiffness values in relation to the characteristic size thereof, both axially and radially. Therefore, it is necessary to use multiple springs in parallel to obtain an adequate force response. - Assembly and tolerance complexity: Using multiple springs in parallel implies smaller tolerances to avoid problems during the assembly.

[0013] - High costs and special materials : Special materials and treatments are necessary to ensure the expected lifecycle of the coil springs, especially if the required stiffnesses are high. This results in a higher cost of the final component.

[0014] - Limited size optimization: The overall size of the eBPS (Electronic Brake Pedal Simulator) system cannot be optimized. In order to obtain the desired stiffness values, the size of the springs is substantially fixed; therefore, the length of the coil springs limits the minimum length of the block, and the radial footprint of the block is also closely related to the diameters of the coil springs.

[0015] Discontinuous load curves: A variable but often discontinuous load curve can be obtained with the coil springs, due to the sequential activation of the springs in series. This can lead to perceivable "skips of force" in the characteristic of the spring.

[0016] Object and subject-matter of the invention

[0017] It is the object of the present invention to provide a braking simulator device which solves the problems and overcomes the drawbacks of the prior art.

[0018] The present invention relates to a device according to the appended claims.

[0019] Detailed description of embodiments of the invention

[0020] List of drawings

[0021] The invention will now be described by way of a nonlimiting illustration, with particular reference to the figures in the accompanying drawings, in which:

[0022] — figure 1 shows a brake pedal simulator device according to the prior art;

[0023] — figure 2 shows a section of a brake pedal simulator according to an embodiment of the invention;

[0024] — figure 3 shows an exploded perspective view of a brake pedal according to an embodiment of the invention .

[0025] It is specified here that elements of different embodiments can be combined together to provide further embodiments, without restrictions, by respecting the technical concept of the invention, as those skilled in the art will effortlessly understand from the description .

[0026] The present description further makes reference to the prior art for the implementation thereof in relation to detail features not described, such as elements of minor importance usually used in the prior art in solutions of the same type, for example.

[0027] When an element is introduced, it is always understood that there can be "at least one" or "one or more".

[0028] When a list of elements or features is given in this description, it is understood that the finding according to the invention "comprises" or alternatively "consists of" such elements.

[0029] When listing features within the same sentence or bullet list, one or more of the single features can be included in the invention without connection with the other features on the list.

[0030] Two or more of the parts (elements, devices, systems) described above can be freely associated and considered as a kit of parts according to the invention.

[0031] Embodiments

[0032] The invention consists in implementing, in the eBPS, a system of conical spring washers to generate the force feedback, so that the size of the component is optimized while simultaneously ensuring an appropriate resistance curve for the user's needs. The present system opposes to the conventional use of coil springs, which has many limitations. Furthermore, the conical spring washers are used in combination with wire springs, so as to take advantage of the properties of the wire springs for low stiffnesses and long strokes, and those of conical spring washers for high stiffnesses and small displacements.

[0033] The operation thereof can be inferred by observing Figure 2 and Figure 3, in which a simplified eBPS assembly is shown.

[0034] With reference to Figures 2 and 3, when the user presses the input command, he / she actuates the floating element 200 by means of a mechanical connection. The latter, sliding inside the eBPS casing 100, compresses a first coil spring 300. The use of a coil spring 300 for the first actuation part is necessary to associate a low resistance with the first part of the pedal pressure (low stiffness zone of the resistance curve). This first part of the resistance curve ends when the floating element 200 (with the tip 250 extending towards the inside of the coil spring 300) strikes the tip 450 of the shock absorber pin 400. The tip 450 also penetrates into the coil spring in the opposite direction with respect to the tip 250 of the floating element, after a predetermined compression of the coil spring 300.

[0035] The shock absorber pin 400 is an element which, when the command is not actuated, rests on a first abutment 150 inside the cylindrical seat 100, by virtue of a radially outermost element 455 coaxial to the tip 450 according to an optional aspect of the invention, preloading the first stack of conical spring washers 500.

[0036] After the contact between the tip 250 of the floating element 200 and the tip 450 of the shock absorber pin of the absorber 400, the stroke resistance is provided by the first stack of conical spring washers 500. Similarly, while the stroke continues, the tail 460 of the shock absorber pin 400, opposite to the tip 450, comes into contact with a recess 650 (optional) of the shock absorber ring 600 (generally, it comes into contact with the shock absorber ring 600), which is placed after the shock absorber pin 400 on the side of the tail 460, thus actuating the second stack of conical spring washers 700 to enter the final part of the resistance curve. The second stack of conical spring washers extends from the shock absorber ring 600 to a final absorber element 900. In particular, the shock absorber ring has a central element 650 which penetrates into said second plurality of conical spring washers 700.

[0037] When the system is at rest, the shock absorber ring 600 also rests on a second abutment 160 obtained in the housing 100, by virtue of an element 655 preferably radially outermost and coaxial to the central element 650, preloading the second stack of conical spring washers 700. Such mechanical abutments can be provided to preload the springs, allowing the fatigue life and vibration life of the conical spring washers themselves to be improved. Furthermore, a design of this type reduces the operating stroke variability of each spring pack. This differs from the prior art, in which all the conical spring washers are mutually in series and in parallel to a wire spring. This does not allow limiting the pedal curve variability and the stroke of the conical spring washers themselves, worsening the fatigue life.

[0038] The final part of the system is closed by an absorber cap 900 provided with an O-ring 800 to prevent the entry of dirt and dust into the casing 100.

[0039] United States Patent US 2021 / 0291797 Al describes a pedal force simulator. The invention, on the other hand, focuses on the creation of a brake pedal simulator which specifically uses conical spring washers to generate the force feedback. Unlike the patent, which employs a general elastic element in the stacks of conical spring washers, the invention suggests a system which starts with a coil spring to provide low resistance in the initial step of the pedal actuation.

[0040] The activation sequence of the springs differs significantly. In the patent, the elastic element first interacts with only one stack of conical spring washers, and the additional stacks are compressed only when the restoring force reaches a sufficient level. The invention provides instead that, after the compression of the initial coil spring, a shock absorber pin activates a first stack of conical spring washers. The tail of this shock absorber pin then engages a shock absorber ring, which in turn activates a second stack of conical spring washers, defining the final part of the resistance curve.

[0041] Another important difference between the two approaches relates to the interaction between the elastic element and the pin. In the patent, an actuator pin on the piston enters the recess of the coil spring, and thus the latter works in parallel with the conical spring washers, while in the invention, when the float and the shock absorber pin come into contact, the compression of the coil spring is concluded, and there is only the compression of the conical spring washers. This difference in the interaction and penetration between pin and spring has a technical effect on the force feedback mode and progressiveness, allowing a progressive and smoother activation in the invention.

[0042] As for the mechanical pretensioning stops, although the mentioned patent includes them, these are not on the cylindrical housing as in the invention. In the invention, a first abutment inside the cylindrical casing accommodates an element of the shock absorber pin at rest, preloading the first plurality of conical spring washers. Similarly, a second abutment inside the cylindrical casing accommodates an element of the shock absorber disc at rest, preloading the second plurality of conical spring washers. This is consistent with the progressive actuation in series of the springs described above: with pins in the internal elements, the actuation in series would not be achieved. Furthermore, the effectiveness of this choice comprises the fact that the preload is directly managed by the fixed structural elements of the housing, contributing to the stability and precision of the system.

[0043] Advantages of the invention

[0044] Using disc springs has the dual purpose of considerably reducing the size of the reaction element (with respect to a coil spring), while simultaneously providing considerably higher stiffness values. The advantages deriving from the use of conical spring washers can be summarized as follows:

[0045] - Very large loads can be supported with a small installation space, which is a crucial aspect for the eBPS: for example, the overall size of the ePedal is the most critical parameter in the design of motorcycle applications, because it must be installed as close as possible to the pedal master cylinder . - The characteristic curve of the spring can be designed as linear, regressive or progressive with an appropriate relative arrangement of the individual discs. This is a great advantage as compared to the use of coil springs; with the latter, it is possible to obtain a variable but discontinuous load curve, resulting in the activation of springs in series, while with the conical spring washers, it is possible to obtain a smooth and progressive load curve directly;

[0046] - By virtue of the virtually unlimited number of possible combinations of the individual conical spring washers, the characteristic curve and the length of the stack can be easily adapted as needed; considering the same number of discs, it is possible to obtain completely different load curves by simply positioning them differently from one another;

[0047] - The service life under dynamic load conditions is highly long if the spring is suitably dimensioned and preloaded (to avoid alternating tensioncompression stresses);

[0048] - With an appropriate arrangement of the individual discs, it is possible to achieve a wide damping effect, which is a desirable aspect for the application discussed here.

[0049] Preferred embodiments have been described above and variations of the present invention have been suggested, but it should be understood that those skilled in the art may make modifications and changes without departing from the related scope of protection, as defined by the appended claims.

Claims

CLAIMS1. A braking simulator device (1000) with conical spring washers, comprising a cylindrical casing (100) configured for internal sliding of a floating element (200) along a cylinder axis (X), wherein the floating element (200) is axially pushed by a coil spring (300) which is configured to push, on one side, on one end of the floating element (200) and, on the other side, on a shock absorber pin (400), wherein said end of the floating element (200) has a floating element tip (250) which penetrates into the coil spring and is configured to abut against a tip (450) of the shock absorber pin (400), which also axially penetrates into the coil spring in the direction opposite to the floating element tip (250), after a predetermined compression of the coil spring (300), the device (1000) being characterized in that:- a shock absorber ring (600) is comprised, arranged coaxially in front of a shock absorber pin tail (460) opposite to said shock absorber pin tip (450);- a first plurality of conical spring washers (500) is arranged axially in series between said shock absorber pin (400) and said shock absorber ring (600), wherein the shock absorber pin tail (460) penetrates into said first plurality of conical spring washers;- a final absorber element (900) is further provided, arranged coaxially after said shock absorber ring (600) on the side opposite to said shock absorberpin tail (460);- a second plurality of conical spring washers (700) is arranged axially in series between said shock absorber ring (600) and said final absorber element (900), wherein said shock absorber ring has a central element (650) which penetrates into said second plurality of conical spring washers (700); wherein said shock absorber pin tail (460) is configured to abut against said shock absorber ring (600) after a first predetermined axial stroke, and wherein said central element (650) of shock absorber ring (600) is configured to abut against said final absorber element (900) after a second predetermined axial stroke.

2. The braking simulator device (1000) according to claim 1, wherein a first abutment (150) is present within the cylindrical casing (100), configured to abuttingly accommodate an element (455) of the shock absorber pin (400) at rest, so as to preload the first plurality of conical spring washers (500).

3. The braking simulator device (1000) according to claim 1 or 2, wherein a second abutment (160) is present within the cylindrical casing (100) configured to abuttingly accommodate an element (655) of the shock absorber ring (600) at rest, so as to preload the second plurality of conical spring washers (700).

4. The braking simulator device (1000) according to one of claims 1 to 3, wherein the final absorber element(900) is provided with an O-ring (800) to prevent the entry of dirt and dust into the cylindrical casing (100).

5. The braking simulator device (1000) according to one of claims 1 to 4, wherein the cylindrical casing (100) comprises a first abutment (150) on the inner surface thereof configured to accommodate an element (455) of the shock absorber pin (400) in a resting position, preloading the first plurality of conical spring washers (500), and a second abutment (160) configured to accommodate an element (655) of the shock absorber ring (600) in a resting position, preloading the second plurality of conical spring washers (700).

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