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CN-116669999-B - Valve unit for an anti-lock brake system

CN116669999BCN 116669999 BCN116669999 BCN 116669999BCN-116669999-B

Abstract

A valve unit (10) for an anti-lock braking system (ABS) comprises a valve body (11), a piston (18) movable in the valve body and a resilient element (34) acting on the piston. The valve body has an outlet port (14), an inlet port (17), a main chamber (15) in communication with the outlet port, an expansion chamber (16) having an outflow channel (51) enabling fluid communication between the main chamber and the expansion chamber, and a bypass channel (50) between the inlet port and the outlet port. The piston (18) is movable in the main chamber (15) and has a longitudinal through cavity (31). The piston has a first lateral surface facing away from the outlet port and a second lateral surface opposite the first lateral surface and facing away from the outlet port, wherein the area of the first lateral surface is smaller than the area of the second lateral surface. The resilient element (34) applies a resilient force to move the piston (18) away from the outlet port (14). The valve unit (10) is activatable by the pressure of the brake fluid in the main chamber (15).

Inventors

  • SANDRO BONARDO

Assignees

  • 莱卡姆动力传动系统责任有限公司

Dates

Publication Date
20260512
Application Date
20211123
Priority Date
20201125

Claims (18)

  1. 1. A valve unit for a vehicle anti-lock braking system, the valve unit comprising: A valve body (11) having an outlet port (14) hydraulically connectable to the brake caliper (G), an inlet port (17) hydraulically connectable to the master cylinder (M), a main chamber (15) in fluid communication with the outlet port (14), an expansion chamber (16) having an outflow channel (51) establishing fluid communication between the main chamber (15) and the expansion chamber (16), and a bypass channel (50) establishing fluid communication between the inlet port (17) and the outlet port (14); A piston (18) longitudinally movable in the main chamber (15) and having a longitudinal cavity (31) extending through the piston between an end face (32) of the piston facing the outlet port (14) and a lateral passage (33) leading to a lateral surface of the piston, the piston (18) generally having a first lateral surface facing the outlet port (14) and a second lateral surface opposite the first lateral surface and facing away from the outlet port (14), wherein the area of the first lateral surface is smaller than the area of the second lateral surface; at least one elastic element (34) exerting an elastic force to move the piston (18) away from the outlet port (14), Wherein the piston (18) has two selectable operating positions: in a first position in normal braking conditions, in which the force of the elastic element exceeds the longitudinal component of the hydraulic thrust of the braking fluid present in the main chamber (15), whereby the piston (18) moves away from the outlet port (14) and blocks the outflow channel (51) without blocking the bypass channel (50), and In a second position of the valve unit in an activated condition, wherein the hydraulic thrust of the brake fluid present in the main chamber (15) has a longitudinal component exceeding the force exerted by the elastic element (34), whereby the piston (18) moves towards the outlet port (14) and blocks a bypass channel (50) without blocking the outflow channel (51).
  2. 2. The valve unit of claim 1, wherein: the main chamber (15) forms: a first section (19) arranged closer to the outlet port (14) and having a first diameter (D1), A third section (21) arranged remote from the outlet port (14) and having a third diameter (D3) smaller than the first diameter (D1), and -A second intermediate section (20) located between the first section (19) and the third section (21), having a second diameter (D2) greater than the first diameter (D1); the piston (18) comprises: A first portion (22) sealingly sliding in a first section (19) of the main chamber (15), An intermediate portion (23) which slides sealingly in a second intermediate section (20) of the main chamber, and A third portion (24) sealingly sliding in a third section (21) of the main chamber; Thereby making it possible to The first transverse surface has an area of a circle having a first diameter (D1), and The second transverse surface has the area of an annular crown having an outer circumference with a diameter corresponding to the second diameter (D2) and an inner circumference with a diameter corresponding to the third diameter (D3).
  3. 3. Valve unit according to claim 1, further comprising means (42) for adjusting the elastic force exerted by the elastic element (34) on the piston (18).
  4. 4. A valve unit according to claim 3, wherein the valve unit comprises: A transverse shoulder (35) facing away from the outlet port (14) and integral with the valve body (11), A transverse lining wall (36) facing said transverse shoulder (35) and longitudinally spaced therefrom, A valve stem (37) connecting the transverse lining (36) to the piston (18) and integrating the piston with the transverse lining (36) in the longitudinal direction, And wherein the elastic element (34) is a compression spring, which is compressed longitudinally between the lateral lining wall (36) and the lateral shoulder (35).
  5. 5. Valve unit according to claim 4, wherein the means (42) for adjusting the elastic force exerted by the elastic element (34) on the piston (18) are configured to adjust the longitudinal distance between the lateral lining wall (36) and the lateral shoulder (35).
  6. 6. Valve unit according to claim 5, wherein the valve stem (37) comprises a threaded stem portion engaged in a corresponding threaded through hole (39) formed through the lateral lining wall (36), whereby a rotation applied to the valve stem about the central longitudinal axis (37A) of the valve stem itself causes a variation of the longitudinal distance between the lateral lining wall (36) and the piston (18).
  7. 7. Valve unit according to claim 6, wherein the valve stem (37) has an enlarged terminal head (40) of circular cross-section, which engages in a groove (41) formed in the piston (18).
  8. 8. Valve unit according to claim 6 or 7, wherein the valve stem (37) has a central longitudinal axis (37A) that is eccentric with respect to a longitudinal central axis (18A) of the piston (18).
  9. 9. Valve unit according to claim 6 or 7, wherein the valve stem (37) has a central longitudinal axis (37A) and the lateral lining wall (36) has an outer peripheral edge, at least a part of which has a lateral distance (P1) from the central longitudinal axis (37A) that is greater than the minimum lateral distance (P2) between the central longitudinal axis (37A) and a surface of the valve body (11) that faces the valve stem (37) in the lateral direction and that acts as a stop against rotation of the lateral lining wall (36) when the valve stem (37) is rotated.
  10. 10. A valve unit according to claim 6, wherein the device (42) is rotatably coupled to the valve stem (37) by a splined longitudinal coupling (44) allowing relative longitudinal movement between the device (42) and valve stem (37).
  11. 11. Valve unit according to any one of claims 4 to 7, wherein the lateral lining wall (36) is accommodated with lateral play within a chamber formed by the valve body and is longitudinally movable within a chamber (38) formed by the valve body (11).
  12. 12. A valve unit according to claim 1 or 2 or 3, wherein the elastic element (34) is an elastic traction element having a first end constrained to the piston (18) and a second end constrained to a transversal lining (36) integral with the valve body (11).
  13. 13. Valve unit according to claim 12, wherein the lateral lining wall (36) is fixed with respect to the valve body (11) or adjustable in longitudinal position, thereby adjusting the pretension of the elastic element (34) and thus the traction force acting on the piston away from the outlet port (14).
  14. 14. A valve unit according to claim 3, wherein the means (42) comprise an electric drive electrically connectable to an Electronic Control Unit (ECU) mounted on a carrier plate of the vehicle.
  15. 15. A valve unit according to claim 3, wherein the means (42) comprise a manual adjustment mechanism.
  16. 16. Valve unit according to claim 1, wherein the expansion chamber (16) accommodates: a longitudinally slidable float valve element (61), and A secondary spring element (66) pushing the floating valve element (61) towards the inlet port (17), And wherein the expansion chamber (16) is in fluid communication with the inlet port (17) through a passage (68), wherein a one-way valve (69, 70, 71) is mounted to allow brake fluid to flow through the passage from the expansion chamber (16) towards the inlet port (17) in only one direction (B).
  17. 17. The valve unit of claim 16, wherein: The floating valve element (61) is movable within the expansion chamber (16) between a shoulder (64) of the valve body (11) arranged in the expansion chamber closest to the inlet port (17) and a transverse wall (67) arranged in the expansion chamber furthest from the inlet port, and wherein The outflow channel (51) opens into the expansion chamber (16) at a location located longitudinally adjacent the shoulder (64).
  18. 18. Valve unit according to claim 4, wherein the elastic element (34) comprises at least two compression springs between the lateral lining wall (36) and the lateral shoulder (35), wherein a first spring is always longitudinally precompressed between the lateral lining wall (36) and the lateral shoulder (35), and a second spring has a shorter free length than the first spring and is not longitudinally precompressed between the lateral lining wall (36) and the lateral shoulder (35).

Description

Valve unit for an anti-lock brake system Technical Field The present invention relates to a valve unit for a hydraulic brake system to control an anti-lock function of wheels of a vehicle. The valve system is suitable for use in motor and non-motor vehicles such as bicycles. Background Anti-lock braking systems ("ABS") have been installed on vehicles having hydraulic brakes to prevent skidding or uncontrolled skidding, thereby reducing the impact of sudden stops. One such system is shown in fig. 1, in which four wheels of a motor vehicle are equipped with brake discs E1-E4 and associated sensors S1-S4, which are operable to face the speech wheels F1-F4 or equivalent elements rotationally integral with the brake discs. According to a known mode, the sensors S1-S4 detect the rotational speed of the wheel with which they are associated and send a signal representative of the rotational speed, for example through the wires N1-N4, to an Electronic Control Unit (ECU) or module, which processes the received speed signal. Each brake disc is associated with a brake caliper G1-G4. The master cylinder M operated by the foot controller C activates the brake calipers through respective hydraulic lines H1-H4, on each of which a valve unit ABS1-ABS4 is mounted. Each ABS valve unit controls the flow and pressure of brake fluid to the associated brake caliper in response to electronic control signals from the electronic control unit ECU. When the ECU detects a condition indicating impending wheel lock, it activates the corresponding ABS valve to reduce the hydraulic pressure on the brake at the affected wheel, thereby reducing the braking force on that wheel so that the wheel remains braked but can rotate. This process is repeated continuously during braking, several times per second, to prevent the vehicle from slipping. DE 101 58 a1 discloses an anti-lock brake system for bicycles, comprising a master cylinder and a slave cylinder integrated into a hydraulic actuator forming a hydraulically closed compact unit with an outlet valve and a check valve and a low pressure liquid hydraulic reservoir. The system also includes an electronic controller, at least one wheel brake, at least one speed sensor, and a hydraulic actuator having a low pressure hydraulic fluid reservoir connected to the drain valve and the isolation valve. A check valve is connected in parallel with the discharge valve and downstream from the isolation valve and the discharge valve from the hydraulic cylinder. EP 3 392,105 A2 describes a hydraulic brake system for a bicycle comprising two electrically operated valve assemblies. Each valve assembly is independently operated by a respective electric actuator. The first valve assembly is for blocking brake fluid between the master cylinder and the brake caliper, and the second valve assembly is for opening parallel passages hydraulically connecting the brake caliper and the accumulator. The two electric actuators are supplied with power in a predetermined sequence by the ECU, respectively. The two valve assemblies are located on parallel branches of a hydraulic circuit connecting a master cylinder operated by a handle and a brake caliper. During normal braking, the first valve assembly is open to allow direct fluid communication between the master cylinder and the brake caliper, while the second valve assembly is closed. In an emergency braking condition, the first electric actuator closes the first valve assembly to block pressure input from the handle to block pressure from the first valve assembly to the caliper to prevent further pressure increase on the caliper in the event of an impending wheel lock. The second electric actuator opens the second valve to allow pressure to drain into an accumulator located upstream of the second valve in the parallel passage. Thus, the pressure on the caliper is reduced, releasing the brake. Other ABS systems include a valve unit that includes a piston mounted in a hydraulic line. The piston is controlled by an electric actuator (solenoid valve) which moves the piston back and forth to change the volume in the hydraulic line, thereby regulating the pressure in the brake circuit. Disclosure of Invention According to the prior art, the main object of the present invention is to provide an ABS valve unit that can be actuated to intervene in the case of locking the braked wheel, instead of being electrically controlled by means of a conventional actuator. The present invention provides an ABS valve unit that is actuated by brake fluid pressure present in a hydraulic circuit of a brake system. According to one aspect, the present invention discloses a valve unit for a hydraulic brake system for controlling an anti-lock function of a wheel of a vehicle, as defined in claim 1. Preferred embodiments of the invention are defined in the dependent claims. Generally, a valve unit for an anti-lock brake system of a vehicle includes a valve body, a movable piston in the valve body, and