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DE-112024002496-T5 - Valve unit for an anti-lock braking system for bicycles

DE112024002496T5DE 112024002496 T5DE112024002496 T5DE 112024002496T5DE-112024002496-T5

Abstract

The valve assembly (20) comprises an outer valve body (21) that defines an axially elongated inner cavity (22) in which a piston valve component (23) is slidably actuated. Three stationary annular seals (31, 32, 33) are mounted on the outer valve body within the inner cavity (22) and engage with the piston valve component (23) in a sliding sealing manner: an upstream end seal (31), a downstream end seal (32), and an intermediate seal (33) located within the inner cavity (22) between an inlet port (27) and an outlet port (26). The outer valve body (21) does not need to provide a sliding surface for moving seals and can be made of plastic material.

Inventors

  • Sandro Bonardo
  • Andrea Canestrari

Assignees

  • RAICAM DRIVELINE S.r.l.

Dates

Publication Date
20260513
Application Date
20240604
Priority Date
20230612

Claims (10)

  1. Valve unit (20) for a hydraulic anti-lock braking system for a bicycle, the valve unit comprising: an outer valve body (21) defining an inner cavity (22) having an axially elongated shape; a piston valve component (23) axially displaceable within the inner cavity (22) and separating an upstream chamber (25) from a downstream chamber (24) within the inner cavity (22), the piston valve component (23) being connectable to an electric motor (28) for controlling the axial position of the piston valve component (23) along the inner cavity (22); an inlet port (27) formed in the outer valve body (21) for establishing a fluid connection between the upstream chamber (25) and a brake-actuating hydraulic master cylinder (13); an outlet port (26) formed in the outer valve body (21) for establishing a fluid connection between the downstream chamber (24) and a brake caliper (11) operatively connected to the valve unit (20), wherein the inlet port (27) and the outlet port (26) are axially spaced apart from each other along the inner cavity (22); wherein the piston valve component (23) has a downstream end section (232) with a diameter (D2), an upstream end section (231) and a central section (233) with a smooth cylindrical surface having a diameter (D3) and one or more radially narrower surfaces (234) extending axially from the smooth cylindrical surface (235) towards the upstream end section (231), wherein the diameter (D3) of the central section (233) is larger than the diameter (D2) of the downstream end section (232); Three stationary annular seals (31, 32, 33) mounted on the outer valve body (21) within the inner cavity (22) and slidingly sealing against the piston valve component (23): (i) an upstream end seal (31) engaging with the upstream end section (231); (ii) a downstream end seal (32) engaging with the downstream end section (232), wherein the upstream and downstream end seals (31, 32) are axially spaced apart such that the inlet port (27) and the outlet port (26) are located axially between the upstream and downstream end seals (31, 32); (iii) an intermediate seal (33) mounted within the inner cavity (22) between the inlet port (27) and the outlet port (26), the piston valve assembly (23) being axially actuated between a normal braking position in which the smooth cylindrical surface (235) is axially displaced with respect to the intermediate seal (33) and is not engaged with it, and the intermediate seal (33) being transversely aligned with and radially separated from the one or more radially narrower surfaces (234), thereby defining one or more corresponding passages (236) between the piston valve assembly (23) and the intermediate seal (33), thereby establishing a fluid connection between the downstream and upstream chambers (24, 25); and at least one fluid-isolating position in which the piston valve component (23) is axially displaced in the direction of the upstream chamber (25) and the intermediate seal (33) engages with the smooth cylindrical surface (235), thereby fluidly isolating the downstream chamber (24) from the upstream chamber (25).
  2. Valve unit according to Claim 1 , wherein the outer valve body (21), which defines the inner cavity (22), is made of plastic material.
  3. Valve unit according to Claim 1 or Claim 2 , wherein the upstream end section (231) of the piston valve component (23) has a diameter (D1) that is smaller than the diameter (D3) of the central section (233).
  4. Valve unit according to Claim 3 , wherein the diameter (D2) of the downstream end section (232) is larger than the diameter (D1) of the upstream end section (231).
  5. Valve unit according to one of the preceding claims, wherein the intermediate seal (33) has a conical lip which tapers towards the upstream chamber (25).
  6. Valve unit according to Claim 1 , wherein one or more radially narrower surfaces (234) comprise axially extending grooves spaced apart in the circumferential direction.
  7. Valve unit according to Claim 1 , wherein the outer valve body (21) is formed as an essentially tubular body with axially opposite open ends and a central, radially thicker wall region (211) providing a transverse surface (212) facing the upstream chamber (25), an upstream hollow tubular insert (35) is fitted within the inner cavity (22) and provides an axial passage to the receiving provides the upstream end section (231) of the piston valve component (23), and wherein the intermediate seal (33) is continuously held in an axial position between the central wall region (211) and the upstream hollow tubular insert (35).
  8. Valve unit according to one of the preceding claims, wherein the valve unit is configured such that the piston valve component (23) can be driven according to a pressure modulation operating mode to perform a linear reciprocating motion and repeatedly and alternately achieve two relatively axially offset fluid-isolating positions: a first fluid-isolating position in which the piston valve component (23) is displaced axially in the direction of the upstream chamber (25) and the intermediate seal (33) is in engagement with the smooth cylindrical surface (235), thereby fluidly isolating the downstream chamber (24) from the upstream chamber (25); and a second fluid-isolating position in which the piston valve component (23) is moved axially further towards and into the upstream chamber (25) and the intermediate seal (33) engages with the smooth cylindrical surface (235), thereby fluidly isolating the downstream chamber (24) from the upstream chamber (25).
  9. Valve unit according to one of the Claims 1 until 7 , wherein the valve unit is configured such that the piston valve component (23) can be driven according to an operating mode to perform a linear reciprocating motion and repeatedly and alternately reach two relatively axially offset positions: the normal braking position in which the smooth cylindrical surface (235) is axially displaced with respect to the intermediate seal (33) and is not engaged with it, and the intermediate seal (33) is transversely aligned with and radially separated from the one or more radially narrower surfaces (234), thereby defining one or more corresponding passages (236) between the piston valve component (23) and the intermediate seal (33), thereby establishing a fluid connection between the downstream and upstream chambers (24, 25); and the at least one fluid-isolating position in which the piston valve component (23) is axially displaced in the direction of the upstream chamber (25) and the intermediate seal (33) engages with the smooth cylindrical surface (235), thereby fluidly isolating the downstream chamber (24) from the upstream chamber (25).
  10. Hydraulic anti-lock braking system for a bicycle, comprising a valve unit (20) according to one of the preceding claims.

Description

Technical field The present invention relates to a valve unit for a hydraulic braking system for controlling the anti-lock braking function of a wheel of a vehicle, in particular a bicycle or an e-bike. background Anti-lock braking systems (“ABS”) are installed on vehicles with hydraulic brakes to prevent skidding by reducing the effects of an abrupt stop. In an ABS braking system, all wheels of a vehicle are equipped with brake discs and associated wheel speed sensors or equivalent elements that are rotationally integrated with the brake discs. The sensors detect the rotational speeds of the wheels to which they are associated and send signals indicating these speeds to an electronic control unit (ECU), which processes the received rotational signals. Each brake disc is associated with a brake caliper. A master cylinder, actuated by a control (hand lever control on a bicycle), activates the brake calipers through a separate hydraulic circuit, each of which has an ABS valve unit. Each ABS valve unit controls the flow and pressure of brake fluid toward its associated brake caliper in response to electrical control signals from the electronic control unit. When the ECU detects a condition indicating an impending wheel lock-up, it actuates the corresponding ABS valve to reduce the hydraulic pressure at the brake on the affected wheel. This reduces the braking force at that wheel, allowing it to remain braked but still rotate. This process is repeated continuously during braking, several times per second, to prevent the vehicle from skidding. WO 2021/205337 A1 Disclosure reveals an ABS actuation device for a hydraulic bicycle brake system, comprising an internal cavity in which a piston valve assembly is slidably mounted, separating an upstream chamber from a downstream chamber. An inlet port establishes a fluid connection between the upstream chamber and a hydraulic master cylinder, actuated by a brake lever. An outlet port connects the downstream chamber to a hydraulic slave cylinder, which acts on a brake caliper. The position of the piston valve assembly is controlled by an electric motor. During normal braking, when there is no need for ABS intervention, the electric motor is inactive, and the piston valve assembly is in an end position facing the downstream chamber. A sealing ring mounted on the piston valve assembly leaves an annular gap between the sealing ring and the cavity wall. This gap connects the upstream and downstream chambers, allowing brake fluid pumped by the master cylinder to flow past the piston valve assembly toward the caliper. In conditions requiring ABS activation, the electric motor is activated, causing the piston valve assembly to move toward the upstream chamber. This engages a reduced-diameter area of the cavity where the sealing ring is located, thus interrupting the fluid connection between the upstream and downstream chambers. In this state, the volume of the downstream chamber increases, resulting in a decrease in the pressure of the brake fluid supplied to the caliper. Overview of the invention A primary object of the present invention is to provide an improved and simplified ABS valve unit that has a simplified design, is easier to manufacture and easier to assemble. Another specific object of the present invention is to provide a valve unit that is more economical to produce, with a valve body made of plastic material. Another object of the invention is to provide a valve unit that has safety features that ensure effective braking even in the event of a failure or loss of electrical power on an e-bike. According to one aspect, the present invention provides a valve unit for a hydraulic braking system for controlling the anti-lock braking function of a vehicle wheel, as defined in claim 1. Preferred embodiments are defined in the dependent claims. In summary, a valve assembly for a hydraulic anti-lock braking system for a bicycle comprises an outer valve body that defines an inner cavity with an axially elongated shape. A piston valve component is mounted to be axially displaceable within the inner cavity and separates an upstream chamber from a downstream chamber within the inner cavity. The piston valve component is equipped with an electric motor to control its axial movement. The valve assembly is connected along the inner cavity. An inlet port is formed in the outer valve body to establish a fluid connection between the upstream chamber and a brake-actuated hydraulic master cylinder. An outlet port is also formed in the outer valve body to establish a fluid connection between the downstream chamber and a brake caliper operatively connected to the valve assembly. The inlet and outlet ports are axially spaced apart along the inner cavity. The piston valve assembly has a downstream end section with a given diameter, an upstream end section, and a central section with a smooth cylindrical surface having a diameter larger than that of the downstream end section. The central