Master cylinders, especially tandem master cylinders, particularly in drive-by-wire braking systems.

Abstract

This concerns master cylinders, particularly braking systems including the TMC. [Solution] A braking system including a TMC1, formed from a substantially cylindrical base body, having an internal space 9 defined therein in which at least one piston 7 moves under the pressure of an actuator, the movement of the actuator controlled by a brake pedal, this control performed via a booster positioned between the actuator and the brake pedal and electronically controlled by an electrical unit, or directly by mechanical coupling with the pedal in the event of booster failure, or via a so-called by-wire electrical coupling between the pedal and an electrical unit that controls an electric motor acting on the actuator, the internal space of the master cylinder is in communication on the one hand with a brake fluid reservoir via at least one inlet pipe 11, and on the other hand with at least one brake hydraulic circuit acting on the brakes via at least one outlet pipe.

Description

TECHNICAL FIELD

[0001] The present invention relates to a braking device comprising a master cylinder, in particular a tandem master cylinder (TMC), and to a master cylinder or TMC of this type. BACKGROUND ART

[0002] Braking systems are critical components for vehicle safety, ensuring effective deceleration and control under diverse driving conditions. Conventional braking systems, particularly systems that use master cylinders, especially tandem master cylinders without additional mechanisms, often face limitations in fluid transmission efficiency for specific applications. Conventional master cylinder designs are based on moving a piston inside a sealing zone to displace brake fluid, which can lead to flow obstructions, especially under severe conditions. Therefore, under very low temperature conditions, the viscosity of the brake fluid increases, which further restricts its movement within the system. Such limitations can reduce braking efficiency and increase the risk of brake failure. SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION

[0003] Current braking systems mainly employ a master cylinder and related components that operate on hydraulic principles. Existing solutions do not adequately address the problem of fluid viscosity caused by low temperatures, or the need to increase fluid intake during emergency situations. This is particularly true for brake-by-wire systems, which present various specific difficulties as they rely on electrical signals to actuate the brakes. The present invention also seeks to solve this problem.

[0004] Therefore, especially in the case of so-called drive-by-wire braking systems, it is desirable to improve the performance of existing braking systems so that they can operate effectively under adverse conditions. In drive-by-wire braking systems, the connection between the brake pedal and the master cylinder is entirely electrically controlled, and in the event of an electrical failure, the driver will be unable to mechanically push the master cylinder to generate the necessary braking pressure with the piston. [Means for solving the problem]

[0005] The present invention aims to overcome the shortcomings of the prior art by providing a braking system including a master cylinder, particularly a TMC. The master cylinder, particularly the TMC, is formed from a substantially cylindrical base body, and an internal space is defined therein in which at least one piston moves under the pressure of an actuator. The movement of the actuator is controlled by a brake pedal, and this control is performed via a booster that is electronically controlled by an electrical unit positioned between the actuator and the brake pedal, or directly by a mechanical coupling with the pedal in the event of booster failure, or by a coupling between the pedal and an electrical unit that controls an electric motor acting on the actuator. The braking system is characterized by the following: the internal space of the master cylinder is in communication on the one hand with a brake fluid reservoir via at least one inlet pipe and on the other hand with at least one brake hydraulic circuit acting on the brakes via at least one outlet pipe, the braking system being provided with at least one suction valve positioned between the brake fluid reservoir and at least one outlet pipe in the fluid path, an electronic controller ESP capable of controlling a pump that creates a negative pressure to open at least one suction valve, and an O-ring for sealing around at least one suction valve. [Effects of the Invention]

[0006] By providing this suction valve, the ESP can complement, and even replace, the pressurizing action of the piston on the brakes in the most severe conditions, especially in the event of piston failure. This ensures that the system always maintains optimal fluid flow and pressure, particularly when the viscosity of the brake fluid increases. Similarly, in the event of an electrical system failure, activating the emergency mode allows for a significant supply of brake fluid, ensuring effective braking. Furthermore, the sealing ring minimizes, or even eliminates, the risk of leakage, thus ensuring that the pressurized fluid flow on the brakes functions reliably and optimally, especially in severe or emergency situations.

[0007] Therefore, the fluid receiving capacity of the braking system is improved.

[0008] In particular, it provides improved braking performance, increased convenience, and a braking system that is especially suitable for so-called by-wire braking.

[0009] Therefore, according to one embodiment, the movement of a mechanical actuator is controlled by an electrical unit that receives a signal from a brake pedal via a wire, and the electrical unit determines the braking force based on this signal, and as a result controls the corresponding operation of the actuator by an electric motor.

[0010] In another embodiment, the brake pedal sends a signal to the ESP via an electrical wire, which determines the braking force based on this signal and, as a result, controls the corresponding operation of the pump with an electric motor.

[0011] The two embodiments described above may be combined with each other, or each may be implemented independently.

[0012] Preferably, at least one suction valve is housed in each inlet pipe of the master cylinder or in the bypass conduit of at least one of each inlet pipe, and an inner annular step is formed on the inner wall of the inlet pipe or bypass conduit, and the faces of the individual suction valves housed in the inlet pipe or individual bypass conduit that face the internal space abut therein.

[0013] Preferably, a recess in the shape of an annular groove is formed on the annular step portion of the inner wall, and a sealing O-ring is housed in this recess.

[0014] Preferably, the sealing O-ring is compressed radially against the bottom of the annular groove by the sides of the individual valves which are press-fitted against the O-ring.

[0015] In particular, at least one valve is housed in an individual inlet pipe, and a bypass pipe is provided extending from a portion of the inlet pipe upstream of each valve to the internal space of the master cylinder, especially the TMC.

[0016] According to another preferred embodiment, at least one suction valve is located in a bypass conduit extending between at least one inlet pipe and an internal space or at least one outlet pipe.

[0017] According to one preferred embodiment, at least one bypass conduit comprises a main through-hole between the outside of the base body and at least one outlet pipe, and an auxiliary through-hole extending between at least one inlet pipe and the main through-hole.

[0018] Preferably, at least one suction valve is located in the main through-hole.

[0019] Preferably, the main through-hole has a longitudinal axis parallel to the longitudinal axis of at least one inlet pipe.

[0020] In one embodiment, a main through-hole extends to the upper side of the master cylinder, and the top surface of this hole is closed by a press-fitted sphere.

[0021] The present invention also particularly relates to a master cylinder intended to form part of a braking system according to the present invention, wherein the master cylinder, in particular a TMC, is formed from a substantially cylindrical base body, inside which an interior space in which at least one piston is movable is defined, the interior space of the master cylinder being communicable, on the one hand, with a brake fluid reservoir via at least one inlet pipe, and on the other hand, with at least one brake hydraulic circuit acting on the brakes via at least one outlet pipe, the master cylinder being characterized in that at least one suction valve arranged between the brake fluid reservoir and the at least one outlet pipe in the fluid path within the base body is provided, and in that a sealing O-ring is provided around the at least one valve.

[0022] By way of example, the drawings show a plurality of preferred embodiments according to the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] [Figure 1] 1 is a schematic view of a vehicle provided with a mechanical braking system including a booster. [Figure 2] 1 is a schematic view of a vehicle provided with a so-called brake-by-wire braking system. [Figure 3] 1 is a longitudinal sectional view showing a part of a tandem master cylinder (TMC) according to one embodiment of the present invention. [Figure 4] FIG. 4 is an enlarged view showing a part of FIG. 3; and [Figure 5] FIG. 5 is an enlarged view showing a part of FIG. 4. DETAILED DESCRIPTION OF EMBODIMENTS FOR CARRYING OUT THE INVENTION

[0024] In FIG. 1, the driver depresses the pedal P (F pedal ), and via the electric unit, the booster B (Fout=F pedal +F boosterA schematic diagram shows an automobile controlling a booster that acts on a primary piston moving within the internal space of the TMC1. The TMC1 includes two outlet pipes, a first outlet pipe 13 and a second outlet pipe 14, which communicate with hydraulic braking circuits C1 and C2, respectively, and these circuits act on a brake caliper 40 under the control of the ESP.

[0025] If the actuator and / or booster fails, the driver can still directly push the piston (the so-called "push-through" or push-through function).

[0026] The ESP receives a braking signal from the pedal via sensors and an electrical unit, and based on this signal, the ESP controls the pump to open two suction valves, the first valve 15 and the second valve 16, located between the brake fluid reservoir 10 and two inlet pipes, the first inlet pipe 11 and the second inlet pipe 12, respectively, within the TMC1, thereby hydraulically controlling or supplementing the braking function in emergencies or when the actuator fails.

[0027] Figure 2 schematically shows a car in which the driver presses pedal P and controls the booster via an electrical unit, and the booster (Fout=F BWA The system acts on the primary piston moving within the internal space of the TMC1. The TMC1 includes two outlet pipes, a first outlet pipe 13 and a second outlet pipe 14, which communicate with a hydraulic braking circuit under the control of the ESP.

[0028] The actuator BWA is not mechanically connected to the pedal; its movement is controlled by an electric motor controlled by an electrical unit 41 based on signals received from sensor 42, and the sensor determines the desired braking force from the pedal stroke and the force applied by the driver.

[0029] If the actuator fails, the operator cannot directly push the piston (the "push-through" function will not be available).

[0030] The ESP receives a braking signal from the pedal via sensors and an electrical unit, and based on this signal, the ESP controls the pump to open the brake fluid reservoir 10 within the TMC1 and two suction valves, the first valve 15 and the second valve 16, located between the two vertically oriented inlet pipes, the first inlet pipe 11 and the second inlet pipe 12, respectively. This allows for or complements hydraulic control of the braking function in emergencies or when the actuator fails.

[0031] Figure 3 shows that the TMC1 includes two pistons, a primary piston 7 and a secondary piston 8, which reciprocate within the internal space 9 of the cylinder under the pressure of an actuator (not shown), thereby forming hydraulic pressure transmitted to individual brake circuits via two outlet pipes, a first outlet pipe 13 and a second outlet pipe 14.

[0032] The two inlet pipes, the first inlet pipe 11 and the second inlet pipe 12, respectively, connect the brake fluid reservoir to the internal space 9.

[0033] Furthermore, two bypass conduits, the first bypass conduit 5 and the second bypass conduit 6, are provided, connecting the internal space 9 and the inlet pipe upstream of the valve. These bypass conduits also extend to the outside of the cylindrical body, particularly as shown at the top of the figure, and are sealed by a sphere that is press-fitted from above.

[0034] These two bypass conduits 5 and 6 each lead to an internal space, allowing the brake fluid from the reservoir to pass through to the internal space when the two pistons are in a resting position and not being pushed by the actuator, and no braking is required. Therefore, when the two pistons are actuated by the actuator during normal operation of the system, increasing the pressure in the internal space, these conduits ensure a fluid supply to actuate the brakes.

[0035] On the other hand, each inlet pipe is equipped with individual suction valves 15 and 16, which, when the ESP operates the pump (not shown), can open additional communication points between the reservoir and the internal space. These communication points are not obstructed even if the piston is unintentionally pushed into the pushed-in position and becomes blocked.

[0036] On the other hand, when the piston is functioning correctly, these valves can increase the amount of brake fluid delivered to the internal space by suction, thereby improving the flow of brake fluid and thus increasing braking efficiency, especially in harsh conditions where, for example, increased fluid viscosity negatively affects the flow.

[0037] The inner walls of the two inlet pipes 11 and 12, the first and second, include stepped sections 17, and surfaces 18 facing the internal spaces 9 of the individual valves housed in the individual inlet pipes abut therewith.

[0038] Above the stepped portion 17 (i.e., on the side opposite to the internal space), a recess in the shape of an annular groove 20 is formed, and a sealing O-ring 19 is housed in this recess. In this embodiment, this same stepped portion 17 forms one of the walls of the annular groove 20 that supports the sealing O-ring. However, without departing from the scope of the present invention, two separate stepped portions may be provided for the sealing O-ring and for the valve surface facing the internal space, thereby separating the inner surface of the annular groove 20 from the stepped portion 17 with which the surface 18 abuts.

[0039] The annular side surface 21 of each valve abuts laterally against the O-ring, compressing it sufficiently to achieve a seal, which prevents brake fluid from moving across the O-ring from the bottom to the top of the figure.

[0040] To achieve this level of sealing, the valve is press-fitted into the O-ring, which is then pushed back laterally and deformed so that its cross-section becomes elliptical, as shown in the diagram.

[0041] By incorporating a sealing O-ring in this manner, the geometric shape and placement of the O-ring are optimized, ensuring effective and reliable sealing while minimizing the risk of fluid leakage. The inherent flexibility of the sealing O-ring allows it to adapt to changes in pressure and temperature, thereby improving the ring's durability and performance over time. Furthermore, this design ensures that the O-ring is always in contact with the sealing surface, providing a high level of sealing that can withstand the harsh conditions of hydraulic systems.

[0042] In particular, the body of the TMC can be made of metal, especially aluminum. The valve can be made of steel. [Explanation of Symbols]

[0043] 1 TMC 7, 8 pistons 9 Interior space 10 Brake fluid reservoir 11, 12 Inlet pipe 13, 14 Outlet pipe 15, 16 Suction valve 17 Step section 18. Surfaces facing the internal space 9 of each valve 19. O-ring for sealing 20 Recesses in the shape of annular grooves 21 Annular side of the valve 40 Brake caliper 41 Electrical Unit 42 sensors P pedal B Booster C1, C2 Hydraulic Braking Circuits

Claims

1. A braking system comprising a master cylinder, particularly a TMC, formed from a substantially cylindrical base body, wherein an internal space is defined therein, within which at least one piston moves under the pressure of an actuator, the movement of the actuator is controlled by a brake pedal, and this control is performed via a booster positioned between the actuator and the brake pedal and electronically controlled by an electrical unit, or directly by mechanical coupling with the pedal in the event of a booster failure, or via a so-called by-wire electrical coupling between the pedal and an electrical unit that controls an electric motor acting on the actuator, wherein the internal space of the master cylinder is in communication on the one hand with a brake fluid reservoir via at least one inlet pipe, and on the other hand with at least one brake hydraulic circuit acting on the brakes via at least one outlet pipe, wherein at least one suction valve is provided positioned between the brake fluid reservoir and at least one outlet pipe in the fluid path, an electronic controller ESP capable of controlling a pump that creates negative pressure to open at least one suction valve is provided, and an O-ring for sealing is provided around at least one valve.

2. The system according to claim 1, characterized in that the movement of a mechanical actuator is controlled by an electrical unit that receives a signal from a brake pedal via a wire, the electrical unit determines the braking force based on this signal, and as a result controls the corresponding operation of the actuator by an electric motor.

3. The system according to claim 1 or 2, characterized in that the brake pedal sends a signal to the ESP via an electrical wire, the ESP determines the braking force based on this signal, and as a result controls the corresponding operation of the pump with an electric motor.

4. The system according to any one of claims 1 to 3, characterized in that at least one suction valve is housed in each inlet pipe of a master cylinder or in a bypass conduit of at least one of each inlet pipe, an inner annular step is formed on the inner wall of the inlet pipe or bypass conduit, and the surface of each suction valve housed in the inlet pipe or individual bypass conduit facing the internal space abuts against therein.

5. The system according to claim 4, characterized in that a recess in the shape of an annular groove is formed on the annular stepped portion of the inner wall, and a sealing O-ring is housed in this recess.

6. The system according to claim 5, characterized in that the sealing O-ring is compressed radially with respect to the bottom of the annular groove by the sides of the individual valves which are press-fitted with respect to the O-ring.

7. The system according to any one of claims 1 to 6, characterized in that at least one valve is housed in an individual inlet pipe, and a bypass pipe is provided extending from a portion of the inlet pipe upstream of the individual valve to the internal space of a master cylinder, particularly the TMC.

8. The system according to any one of claims 1 to 6, characterized in that at least one suction valve is located in a bypass conduit extending between at least one inlet pipe and an internal space or at least one outlet pipe.

9. In particular, a master cylinder for forming part of a braking system according to any one of claims 1 to 8, the master cylinder being formed from a substantially cylindrical base body, having an internal space defined therein in which at least one piston can move, and the internal space of the master cylinder being able to communicate on the one hand with a brake fluid reservoir via at least one inlet pipe, and on the other hand with at least one brake hydraulic circuit acting on the brakes via at least one outlet pipe, wherein at least one suction valve is provided in the fluid path within the base body, between the brake fluid reservoir and at least one outlet pipe, and a sealing O-ring is provided around at least one valve.

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