An Anti-lock control unit for the hydraulic brakes of a handlebar-guided vehicle

Abstract

An anti-lock control unit for the hydraulic brakes of a handlebar-guided vehicle A hydraulic brake control unit for a handlebar-guided vehicle comprises a brake master cylinder (13) configured to be mounted externally on a handlebar tube (20), while internally to the handlebar tube two valves (50, 70) are mounted, arranged at opposite ends of a cartridge device (24) and electrically controlled so as to perform an anti-lock braking control.

Description

[0001] An anti-lock control unit for the hydraulic brakes of a handlebar- guided vehicle

[0002] Technical field

[0003] The present invention relates to an anti-lock control unit for the hydraulic brakes of a handlebar-guided vehicle, such as a bicycle or an electric bicycle.

[0004] Background art

[0005] Anti-lock braking systems ("ABS") have been installed on vehicles with hydraulic brakes in order to prevent skidding, thereby reducing the effects of stopping abruptly. In an ABS braking system, all of the wheels of a vehicle are equipped with brake discs and associated phonic wheels or equivalent elements that are integrated with brake discs. Sensors detect the rotational speeds of wheels to which they are associated and send signals indicative of the rotation speeds to an electronic control unit (ECU) which processes the rotational signals received. A brake caliper is associated with each brake disc. A pump, operated by a control member (a manual control lever on a bicycle), activates the brake calipers through the respective hydraulic circuits, on each of which an ABS valve unit is installed. Each ABS valve unit, in response to electrical control signals from the electronic control unit, controls the flow and pressure of brake fluid to an associated brake caliper. When the ECU detects a condition indicative of the imminent locking of a wheel, it activates the respective ABS valve such as to reduce the hydraulic pressure on the brake at the affected wheel, thus reducing the braking force on this wheel, in such a way that the wheel remains braked but may rotate. This process is continuously repeated during braking, several times per second thereby preventing the vehicle from swerving.

[0006] Several anti-lock systems for bicycles (motorcycles, bicycles and electric bicycles), and products for all of these types of vehicles are known. For example, EP 3 392 104 Al discloses an ABS valve unit mounted on a bracket beneath the handlebars of a bicycle. WO 2021 / 205334 Al discloses two other mounting devices for an ABS unit, one mounted on the front fork of a bicycle, the other mounted inside one of the tubes of a bicycle frame. Known mounting solutions have the disadvantage of mounting the ABS unit in a position that is unsightly and vulnerable to external damage. In the case of the frame mounting option, said frame must be designed and constructed specifically so as to accommodate an ABS system, which is expensive and may add additional weight to the bicycle.

[0007] Summary of the invention

[0008] A main object of the present invention is to provide an improved anti-lock control unit in which the components of the anti-lock system are protected from damage and are not visible from the outside. Another object of the invention is to simplify the hydraulic connections between the components of a hydraulic brake control unit in an anti-lock braking control system.

[0009] According to one aspect, the present invention provides a hydraulic brake control unit for a hydraulic braking system for controlling the anti-lock function of a vehicle wheel, as defined in claim 1. Preferred embodiments are defined in the dependent claims.

[0010] In summary, according to one aspect, the present disclosure relates to a hydraulic brake control unit for a handlebar-guided vehicle equipped with an anti-lock braking control system, the vehicle comprising a handlebar tube extending in an axial direction. The control unit comprises: a brake master cylinder configured to be mounted externally on the handlebar tube to apply a brake fluid pressure to at least one brake on the vehicle; a cartridge device of axially elongated cylindrical shape, configured to be mounted inside the handlebar tube, wherein the cartridge device provides: a master cylinder side port hydraulically connectable to the brake master cylinder; a brake side port hydraulically connectable to at least one brake; a first axially elongated cavity open at a first axial end of the cartridge device; a second axially elongated cavity open at a second axial end of the cartridge, opposite the first axial end; an accumulator hydraulically connectable to the second axially elongated cavity for receiving an amount of brake fluid from the brake side port and to temporarily retain that amount of brake fluid and subsequently return it to the brake side port; a hold valve accommodated at least partially in the first axially elongated cavity, wherein the hold valve is a normally open valve, controlled by a solenoid and electrically energizable to temporarily occlude fluid communication between the master cylinder side port and the brake side port; a release valve accommodated at least partially in the axially elongated second cavity, wherein the release valve is a normally closed valve, controlled by a solenoid and electrically energizable to temporarily allow fluid communication between the brake side port and the accumulator; formed inside the cartridge device are channels which fluidically connect: the master cylinder side port with the brake side port through the first axially elongated cavity, and the brake side port with the accumulator through the second axially elongated cavity.

[0011] Brief description of the drawings

[0012] In order for the present invention to be well understood, some preferred embodiments will now be described, provided by way of example, with reference to the accompanying drawings, in which:

[0013] Fig. 1 schematically represents the layout of an anti-lock braking system on a handlebar-guided vehicle;

[0014] Figs. 2 to 4 are views of a handlebar assembly comprising a hydraulic brake control unit for a handlebar-guided vehicle equipped with an anti-lock braking control system; and

[0015] Fig. 5 is a schematic axial cross-sectional view of components of the control unit that are mounted inside the handlebars.

[0016] Detailed description

[0017] Referring initially to Fig. 1, schematically shown is the layout of a hydraulic braking system for a handlebar-guided vehicle, typically a bicycle or an e-bike. The braking system comprises an anti-lock braking system (ABS) and a series of mechanical and electromechanical components. The ABS system comprises wheel rotational sensors 10 that are applied to the wheels (not shown) of a vehicle (not shown). The wheels are equipped with brake discs (not shown) and related brake calipers 11 (only one brake caliper is shown), which apply a braking force to the brake pads on a caliper by means of a hydraulic braking circuit 15 and consequently generate a braking torque that acts upon the wheel. A manual brake lever 21 operates a brake master cylinder 13 for generating and controlling the pressure within a hydraulic circuit of a brake 15. Preferably, a pressure sensor 14 detects the pressure of the brake fluid within the hydraulic circuit. Rotational sensors 10 detect the rotational speeds of the wheels to which they are associated and send signals that are indicative of said rotational speeds to a brake control unit (BCU) 16, which is an electronic unit that receives and processes signals from the rotational sensors 10 and from the pressure sensor 14. The electrical signals from the pressure sensor 14 are sent to the BCU in order to control the pressure within the hydraulic circuit 15 of the brake. The electrical signals from the pressure sensor 14 are sent to the BCU 16 through a line 9. A battery B supplies power to the BCU through a power supply line 35. If the vehicle is an electric bicycle, it may be powered by the same battery as the electric drive motor.

[0018] The hydraulic braking system comprises a hydraulic brake control unit which includes, in addition to the brake master cylinder 13, two solenoid valves: a "hold valve" 50, which is a normally open solenoid valve, and a "release valve" 70, which is a normally closed solenoid valve, and an accumulator 90. The hold valve 50, the release valve 70, and the accumulator 90 are integrated into a tube 20 of the vehicle’s handlebars (Figs. 2-5). The brake master cylinder 13 is mounted externally on the handlebar tube 20.

[0019] The accumulator 90 is configured such as to store brake fluid at a controlled pressure during the operation of the ABS system and to reintroduce said brake fluid into the hydraulic circuit such as to make it available to the brake master cylinder once again. The accumulator is arranged within a brake fluid path wherein the access thereof is controlled by the release valve 70. A one-way valve 100, schematically illustrated, is interposed between the hold valve 50 and the brake master cylinder 13 and allows brake fluid to flow from the brake caliper to the brake master cylinder when the pressure in the brake caliper is higher than the pressure in the brake master cylinder.

[0020] The BCU 16 may also have an integrated IMU (Inertial Measurement Unit) 18 which detects acceleration and orientation of the bicycle. Based upon these measurements, the BCU activates the hold valve and the release valve in order to prevent the bicycle from tipping over when the rider brakes excessively on high friction road surfaces and to prevent the controlled wheel from locking when the rider brakes on low friction surfaces.

[0021] The pressure sensor 14 may advantageously be mounted inside the handlebar tube.

[0022] In some embodiments, the BCU 16 may also be mounted inside the handlebar tube or adjacent to the handlebar assembly, for example in an on-board computer fixed to the handlebars.

[0023] The handlebar tube 20 identifies a central axis x. In this context, terms such as "axial" or "axially" should be interpreted as indicating a direction parallel to or coincident with the x- axis. In use, the axis of the handlebars is substantially horizontal and oriented transversely to the direction of advancement of the vehicle.

[0024] A brake control lever 21 is mounted in a pivoted manner by means of a clamp 22 on the handlebar tube 20 in such a way as to be able to rotate about a pin 23 with respect to the axial axis x of the handlebar.

[0025] When the control lever 21 is activated, the brake master cylinder 13 sends pressurized fluid through a tube 111 to a brake master cylinder side port 110 (or inlet port) formed in an axially elongated cylindrical cartridge device 24, fixedly mounted inside the handlebar tube 20.

[0026] The cartridge device 24 forms a series of internal cavities and channels. For constructive reasons, as in the example illustrated in Fig. 5, the cartridge device 24 may comprise the joining of several complementary parts 24a, 24b axially side by side.

[0027] The cartridge device 24 may be made of a plastics material or a metallic material, such as aluminum or the alloys thereof. The cartridge device 24 may be inserted into the handlebar tube 20 through an open end of the handlebar tube.

[0028] The cartridge device 24 forms a delivery port or brake side port 112 that hydraulically connects the control unit to at least one brake caliper in order to deliver pressurized brake fluid to said caliper during braking.

[0029] The cylindrical cartridge device 24 has two axially opposite ends, and forms (Fig. 5): a first axially extended cavity 59 open at a first axial end of the cartridge device, in which the hold valve 50 is at least partially accommodated, and a second axially extended cavity 79 open at a second axial end of the cartridge, in which the release valve 70 is at least partially accommodated.

[0030] The cavities 59 and 79 are axially elongated in directions parallel to the axis x of the handlebar tube.

[0031] The hold valve 50 (Fig. 5) is a normally open solenoid valve which is electrically controlled by a solenoid and may be electrically energized in order to temporarily block fluid communication between the inlet port 110 from the brake master cylinder and the brake side port 112.

[0032] The hold valve 50 is accommodated at least partially within a body 24a formed by the cartridge 24 inserted into the handlebar tube 20.

[0033] A plunger 53 of the hold valve 50 is accommodated, at least partially, axially slidable within the first axially elongated cavity 59.

[0034] An electromagnetic coil 67 is mounted stationary inside the handlebar tube 20 and coaxially surrounds at least one portion of the plunger 53 of the hold valve 50. At least one part of the plunger 53 of the hold valve, in particular the portion of the hold valve plunger that is surrounded by the electromagnetic coil 67, is made of a material with high magnetic permeability and low magnetic hysteresis, such as soft iron.

[0035] A return spring 64 pushes the hold valve plunger 53 away from the cartridge, towards a normally open valve position.

[0036] When supplied with power, the electromagnetic coil 67 generates a magnetic flux that biases the plunger 53 with an axial force that opposes the axial force of the return spring 64 and closes the hold valve 50.

[0037] The release valve 70 is a normally closed solenoid valve, electrically controlled by a solenoid, and may be electrically energized in order to temporarily enable fluid communication between the brake caliper and the accumulator 90.

[0038] The release valve 70 is accommodated at least partially in a body 24b formed by the cartridge 24 inserted into the handlebar tube 20.

[0039] A release valve plunger 73 is accommodated in an axially slidable manner, at least partially inside the second axially elongated cavity 79.

[0040] An electromagnetic coil 83 is mounted stationary inside the handlebar tube 20 and coaxially surrounds at least one portion of the release valve plunger 73. At least part of the release valve plunger 73, in particular the portion of the release valve plunger that is surrounded by the electromagnetic coil 83, is made of a material with high magnetic permeability and low magnetic hysteresis, such as soft iron.

[0041] The accumulator 90 may be hydraulically connected to the outlet port through the release valve 70, when said valve is opened by electrically energizing the electromagnetic coil 83. The release valve plunger 73 has two alternative positions: a normal braking position, wherein the release valve is normally closed, the brake side port 112 is not in communication with the accumulator 90, and an activated or open position, in which the release valve plunger 73 allows brake fluid to partially flow back from the part of the circuit that is communication with the brake side port 112 into the accumulator 90.

[0042] A return spring 80 urges the release valve plunger 73 towards the body 24b of the cartridge and towards the closing position of the release valve, wherein the plunger 73 interrupts fluidic communication between the accumulator and the brake caliper.

[0043] Another return spring 93 biases a plunger 92 inside the accumulator 90 away from the body 24b of the cartridge.

[0044] When powered, the electromagnetic coil 83 generates a magnetic flux that biases the plunger 73 with an axial force that opposes the axial force of the return spring 80 and opens the release valve.

[0045] A network or plurality of internal channels or passages is obtained inside the cartridge device, which internal channels or passages fluidically connect the master cylinder side port 110, the brake side port 112, the first axially extended cavity 59, the second axially extended cavity 79 and the accumulator 90. Such channels are suitably configured in such way that, by selectively activating the hold valve and the release valve, various operating conditions may be obtained, including a condition in which fluid communication between the brake master cylinder side port and the brake side port is temporarily blocked, and a condition in which fluid communication between the brake side port and the accumulator is temporarily permitted.

[0046] A channel 130 connects the brake side port 112 to the second axially extended cavity 79.

[0047] A channel 120, which connects the brake master cylinder side port to the brake side port, comprises a first channel section 121 between the master cylinder side port 110 and the first axially extended cavity, a second channel section 122 extending between the first axially extended cavity and the channel 130.

[0048] A channel 140 extends between the brake master cylinder side port and the second channel section 122 and is provided with a one-way valve 100 interposed between the second channel section 122 and the brake master cylinder side port 110. The one-way valve 100 allows brake fluid to flow from the second channel section 122 to the brake master cylinder side port when the pressure in the second channel section 122 is greater than the pressure in the brake master cylinder, but not vice versa.

[0049] Preferably, the pressure sensor 14 is received in a cavity 141 fluidically communicating with the second channel section 122 by means of a channel 142.

[0050] Operation of the ABS control unit is as follows. During normal riding, the brakes are not operated and the manual brake lever 21 is in the rest position. The brake master cylinder 13 is in a resting condition. Neither the hold valve nor the release valve are activated. The hold valve is normally open and the release valve is normally closed. The brake fluid within the entire circuit of the braking system is at atmospheric pressure.

[0051] During normal braking, the rider exerts a force on the manual brake lever 21 and activates the brake master cylinder 13. The hold valve 50 is still open and the release valve 70 is still closed. Brake fluid flows from the brake master cylinder 13 through the channels 120, 130 into the cartridge device 24 and flows from the brake side port 112 towards the brake caliper.

[0052] Using the hydraulic pressure sensor 14, a control algorithm inside the BCU detects that a braking operation is in progress and monitors the speeds of the wheels and the acceleration of the bicycle.

[0053] If, by means of the control algorithm, the BCU 16 detects the occurrence of a wheel skid or the risk of the bicycle tipping over, the first mitigation action that the ABS system may take is to prevent further fluid from entering the brake caliper, thus preventing any further increase in braking torque at the wheel. This is achieved by activating the hold valve 50. Activating the electromagnetic coil 67 causes the hold valve 50 to close. The plunger 53, moving toward the body of the cartridge 24, occludes any fluid communication within the channel 120 thereby ensuring that a further increase in pressure from the brake master cylinder 13 may not be transmitted to the brake caliper. Brake fluid pressurized by the brake master cylinder fills the channel 140 but is blocked within said channel by the one-way valve 100, which is closed due to the fact that the pressure in the channel 140 is greater than the pressure in the channel section 122.

[0054] If the BCU 16 detects another wheel skid or the risk of the bicycle tipping over, an additional mitigation action may be taken which consists in reducing the pressure in the brake caliper and thus decreasing the braking torque at the wheel. This may allow a skidding wheel to recover adhesion. Said pressure may be reduced by temporarily activating the release valve 70. The activation of the electromagnetic coil 83 causes the plunger 73 to move away from the cartridge 24, opening the port 74, which places the brake side port 112 in fluid communication with the accumulator 90. This allows brake fluid to flow from the brake caliper through the release valve 70 into the chamber of the accumulator 90 where the brake fluid moves the plunger of the accumulator 92 against a loading spring 93.

[0055] Once the braking maneuver has been completed, the rider releases the manual brake lever 21. The hold valve 50 reopens, and the fluidic pressure of the channels 120, 130 returns to the atmospheric level. The loading spring 93 empties the accumulator 90 by sending fluid from the accumulator into the channel 130, after which the release valve is de-energized and the spring 80 closes said release valve.

[0056] Although some specific embodiments of the control unit have been presented, it is to be understood that this information has been provided for illustrative purposes only and that the invention is not to be limited by these in any way. Various modifications will be evident to persons skilled in the art, in the light of the preceding examples. The scope of the invention is limited only by the appended claims.

Claims

CLAIMS1. A hydraulic brake control unit for a handlebar-guided vehicle equipped with an anti- lock braking control system, the vehicle comprising a handlebar tube (20) extending in an axial direction (x), wherein the control unit comprises: a brake master cylinder (13) configured to be mounted externally on the handlebar tube (20) to apply a brake fluid pressure to at least one brake (11) on the vehicle; a cartridge device (24) of axially elongated cylindrical shape configured to be mounted inside the handlebar tube (20), wherein the cartridge device provides: a master cylinder side port (110) hydraulically connectable to the brake master cylinder (13); a brake side port (112) hydraulically connectable to at least one brake (11); a first axially elongated cavity (59) open at a first axial end of the cartridge device (24); a second axially elongated cavity (79) open at a second axial end of the cartridge, opposite the first axial end; an accumulator (90) hydraulically connectable to the second axially elongated cavity for receiving an amount of brake fluid from the brake side port and to temporarily retain that amount of brake fluid and subsequently return it to the brake side port; a hold valve (50) accommodated at least partially in the first axially elongated cavity (59), wherein the hold valve is a normally open valve, controlled by a solenoid (67) and electrically energizable to temporarily occlude fluid communication between the master cylinder side port (110) and the brake side port (112); a release valve (70) accommodated at least partially in the axially elongated second cavity (79), wherein the release valve is a normally closed valve, controlled by a solenoid (83) and electrically energizable to temporarily allow fluid communication between the brake side port (112) and the accumulator (90); channels (120, 130), formed inside the cartridge device (24), which fluidically connect: the master cylinder side port (110) with the brake side port (112) through the first axially elongated cavity (59), andthe brake side port (112) with the accumulator (90) through the second axially elongated cavity (79).

2. A control unit according to claim 1, wherein said channels (120, 130) comprise a channel (130) connecting the brake side port (112) to the axially elongated second cavity (79).

3. A control unit according to claim 2, wherein said channels (120, 130) comprise a channel (120) connecting the master cylinder side port (110) with the brake side port (112), wherein said channel (120) comprises a first channel section (121) between the master cylinder side port (110) and the first axially elongated cavity (59), and a second channel section (122) extending between the first axially elongated cavity and the channel (130).

4. A control unit according to claim 3, wherein within the cartridge device (24) there is also formed a channel (140) extending between the master cylinder side port (110) and said second channel section (122) and wherein the cartridge device is provided with a one-way valve (100) interposed between the second channel section (122) and the master cylinder side port (110), and wherein the one-way valve (100) is configured to allow brake fluid to flow from the second channel section (122) to the master cylinder side port (110) when the pressure in the second channel section (122) is greater than the pressure in the brake master cylinder (13), but not vice versa.

5. A control unit according to claim 3 or 4, further comprising a fluid pressure sensor (14) accommodated in a cavity (141) formed in the cartridge device (24).

6. A control unit according to claim 5, wherein the cavity (141) that accommodates the fluid pressure sensor (14) is fluidically communicating with the brake side port (112).

7. A control unit according to any one of the preceding claims, wherein the cartridge device (24) is composed of the union of two complementary cylindrical parts (24a, 24b)arranged axially side by side, of which a first part (24a) provides the first axially elongated cavity (59) that accommodates at least partially the hold valve (50), and a second part (24b) provides the second axially elongated cavity (79) that accommodates at least partially the release valve (70).

8. A control unit according to claim 7, wherein both the first (24a) and second (24b) parts form sections of the channel (120) establishing fluid communication between the master cylinder side port (110) and the brake side port (112), and of the channel (130) establishing fluid communications between the brake side port (112) and the accumulator (90).

9. A handlebar assembly for a handlebar-guided vehicle, comprising a handlebar tube (20) and at least one hydraulic brake control unit according to any one of the preceding claims, wherein the hold valve (50), the release valve (70) and the cartridge device (24) are mounted inside the handlebar tube (20), and the brake master cylinder (13) is mounted externally on the handlebar tube (20).

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