BRAKE MASTER CYLINDER

Abstract

Brake master cylinder (100), comprising a BLS module (200) for controlling the switching on of a brake light according to an actuation of a piston (111, 112) for controlling the switching on of a brake light according to an actuation of a piston (111, 112) which is provided to be moved back and forth within a cylinder body (110) in which the BLS module (200) comprises: a magnet (220) which is attached to a guide hole (120) which is formed in the cylinder body (110) in a longitudinal direction of the cylinder body; an actuating part (240) which is coupled to the piston in such a way that it is moved together with the piston (111) when the piston is moved; a Hall sensor (252) installed in the cylindrical body (110) at a location corresponding to the magnet (220), for detecting a magnetic flux density of the magnet; and a shielding part (230) which is provided to slide in the guide hole and is moved by the actuating part (240) to shield the Hall sensor from the magnet (220).

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention

[0001] The present invention relates to a brake master cylinder, and more particularly to a brake master cylinder that controls the switching of a brake lamp using a Hall sensor and a magnet installed in the master cylinder. 2. Description of the state of the art

[0002] In general, the master cylinder of a vehicle brake refers to a device for receiving a force used as a boosting force from a pressure difference between the vacuum and the atmosphere from a booster, converting the force into a hydraulic pressure, and transmitting the hydraulic pressure to a cylinder to generate a braking force.

[0003] The brake master cylinder is provided with a unit for detecting the actuation of a piston as a result of pedal input to switch a brake light on or off. As an example, German patent application publication DE 10 2004 014 808 A1 and Korean patent KR 10 1 085 801 B1 disclose master cylinders that switch a brake light using a Hall sensor. Another example of a brake master cylinder is known from publication US 2013 / 0 086 900 A1.

[0004] A conventional brake master cylinder includes a ring-shaped magnet installed in a piston that slides and is moved by pedal action, and a Hall sensor installed in a cylinder body of the master cylinder at a position corresponding to the magnet so that the piston can be moved forward and backward within the cylinder body. The Hall sensor detects the strength of a magnetic force due to the movement of the magnet installed in the piston to illuminate the brake light.

[0005] Generally, the annular magnet installed in the piston has a high magnetic flux density. A rare earth magnet, such as neodymium and samarium, which can be easily miniaturized, is used as the annular magnet. However, in recent years, due to the sudden increase in rare earth prices, the price of rare earth magnets made of rare earth elements has also increased, making the development of replacement technology important. In particular, to use a general magnet instead of a rare earth magnet, the volume of the magnet should be larger to increase the magnetic flux density. Since the interior of the master cylinder is a limited space, replacing the rare earth magnet with a general magnet is difficult. SUMMARY OF THE INVENTION

[0006] The present invention provides a master cylinder that: does not substantially increase the volume of the master cylinder; stably detects the magnetic flux density by moving a shielding member such that a change in the magnetic flux can be generated between a magnet and a Hall sensor; and reduces the volume of the magnet.

[0007] According to the invention, there is provided a brake master cylinder including a BLS module for controlling the turning on of a brake lamp according to an operation of a piston that is intended to be reciprocated within the cylinder body, the BLS module including: a magnet fixed to a guide hole formed in the cylinder body in the longitudinal direction of the cylinder body; an operating part coupled to the piston so as to be moved together with the piston as the piston moves; a Hall sensor installed in the cylinder body at a location corresponding to the magnet for detecting the magnetic flux density of the magnet; and a shielding part slidably provided in the guide hole and moved by the operating part to shield the Hall sensor from the magnet.

[0008] The BLS module may further include an elastic member provided in the guide hole to elastically support the shielding member.

[0009] One end of the shielding part may be opened so that the magnet is received in the shielding part when the shielding part is moved by the actuating part.

[0010] The operating member may include: a plate coupled to the piston; and a rod having a predetermined length, one end of which is coupled to the plate and the opposite end of which is inserted into the guide hole to be coupled to the shielding member.

[0011] A ball member for closing one end of the guide hole may be installed in the guide hole on a side opposite to the side where the rod is inserted.

[0012] A plug member for closing one end of the guide hole may be coupled to the guide hole on a side opposite to the side where the rod is inserted, and a fixing member coupled to or integral with the plug member may be provided to fix the magnet.

[0013] The operating part may include: a plate coupled to the piston; and a rod, one end of which is provided with a support supported by the plate and the opposite end of which is inserted into the guide hole to be coupled to the shielding part, and the plate may include a flange arranged to be concentric with the piston and protruding in a radial direction of the piston, and a coupling part bent from the flange and inserted into and fixed to the inner side of the piston, and the flange may support the support to slidably move the rod when the piston is operated.

[0014] The Hall sensor may be provided in the Hall sensor assembly, and the Hall sensor assembly may be coupled to an outer side of the cylinder body.

[0015] According to one embodiment of the present invention, a guide hole is formed in a brake master cylinder so that a general magnet, which is inexpensive, can be moved forward and backward, and a Hall sensor is provided at a location corresponding to the magnet so that the manufacturing cost can be reduced while the sensitivity of the master cylinder is increased. That is, the sensitivity of the master cylinder can be increased even when a general magnet having a low magnetic flux density is used by minimizing the gap between the magnet and the Hall sensor, and the cost can also be reduced.

[0016] Furthermore, a change in magnetic flux can be stably detected by providing a shielding member that moves between the magnet and the Hall sensor when the plunger is moved to shield the magnetic flux. Therefore, since the size of the magnet can be reduced compared to the prior art while the magnet is fixed in a position facing the Hall sensor, manufacturing costs can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings in which: Fig. 1 is a sectional view illustrating a brake master cylinder according to an embodiment of the present invention; Fig. 2 is a sectional view illustrating an operating state of the brake master cylinder according to the embodiment of the present invention; the Fig. 3 and Fig. 4 are views illustrating an operation of a BLS module provided in the brake master cylinder according to the embodiment of the present invention; and the Fig. 5 and Fig. 6 are sectional views illustrating a brake master cylinder according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are provided to fully convey the spirit of the present invention to those skilled in the art. The present invention is not limited to the embodiments shown herein and may be embodied in other forms. In the drawings, parts not relevant to the description may be omitted in order to more clearly illustrate the present invention, and elements may be enlarged to facilitate understanding of the present invention.

[0019] Fig. 1 is a sectional view illustrating a brake master cylinder according to an embodiment of the present invention. Fig. 2 is a sectional view illustrating an operating state of the brake master cylinder. Fig. 3 and Fig. 4 are views illustrating an operation of a BLS module provided in the brake master cylinder. The Fig. 5 and Fig. 6 are sectional views illustrating a brake master cylinder according to an embodiment of the present invention.

[0020] According to the Fig. 1 to 4, a master cylinder 100 according to an embodiment of the present invention includes a cylinder body 110 having a hollow portion 115, pistons 111 and 112 adapted to reciprocate within the hollow portion 116 of the cylinder body 110, and a brake light sensor (BLS) module 200 installed within the cylinder body 110 to detect the reciprocating motion of the pistons 111 and 112 and control the activation of a brake light. The pistons 111 and 112 include first and second pistons 111 and 112.

[0021] The BLS module 200 includes a magnet fixed to a guide hole 120 formed in the cylinder body 110, a Hall sensor assembly 250 installed outside the master cylinder 100 to detect a magnetic force of the magnet 220, an actuating member 240 coupled to the first piston 111 to be moved together with the first piston 111, a shielding member 230 moved by the actuating member 240 to shield the Hall sensor assembly from the magnet 220, and an elastic member 210 to provide the shielding member 230 with an elastic force.

[0022] More specifically, one end of the cylinder body 110 is opened, and an opposite end thereof has a closed cylindrical shape, and the pistons 111 and 112 provided in the cylinder body 110 to slide forward and backward according to an operation of the brake pedal (not illustrated) by the driver include the first and second pistons 111 and 112.

[0023] A reservoir (not illustrated) in which oil is stored so that the oil can be supplied to the master cylinder 100 is installed at an upper portion of the brake master cylinder 100. In the master cylinder 100, a pressure difference due to an operation of an input shaft (not illustrated) associated with the brake pedal (not illustrated) is transmitted to an output shaft (not illustrated), and the output shaft pushes the first and second pistons 111 and 112 of the master cylinder 100 such that the hydraulic pressure is transmitted to the wheel cylinders (not illustrated) of the wheels to generate a braking force.

[0024] A first fluid pressure chamber 111a, which is a space in which fluid pressure is generated, is formed between the first piston 111 and the second piston 112 inside the cylinder body 110, and a second fluid pressure chamber 112a, which is a space in which fluid pressure is generated, is formed between the second piston 112 and an inner wall of an opposite end of the cylinder body 110. A first return spring 111b and a second return spring 112b for returning the first piston 111 and the second piston 112, respectively, are provided in the fluid pressure chambers 111a and 112a.

[0025] A guide hole 120 is formed in the cylinder body 110, extending in the longitudinal direction of the cylinder body 111. As illustrated, the guide hole 120 is spaced a predetermined distance from the hollow portion 115 and is formed at a lower end of the cylinder body 110 so as to be parallel to the hollow portion 115. A magnet 220, which will be described below, and a rod of the operating member 240 are slidably inserted into the guide hole 120.

[0026] As in the Fig. 1 to 4, the guide hole 120 is closed by a ball part 125 on a side opposite to the side on which the rod 224 of the actuating part 240 is located, or as shown in the Fig. 5 and Fig. 6, a plug part 257 for closing one end of the guide hole 120 may be coupled to the end of the guide hole 120, and a fixing part 255 coupled or integral with the plug part 257 for fixing the magnet 220 may be provided.

[0027] According to an embodiment of the present invention, an actuating part 240 for moving the shielding part 230 for controlling the turning on of the brake lamp according to the forward and backward movement of the pistons 111 and 112 is installed in the first piston 111, and a Hall sensor assembly 250 is installed in the cylinder body 110 at a location corresponding to the magnet 220.

[0028] As in the Fig. 1 to 4, the magnet 220 may be fixed to the guide hole 120 formed in the longitudinal direction of the cylinder body 110. Then, since the shielding member 230 is moved between the magnet 220 and the Hall sensor assembly 250 by the shielding member 230, as described below, at least the magnet 220 should be fixed after being separated from the lower end of the guide hole 120 by a predetermined distance.

[0029] As in the Fig. 5 and Fig. 6, the magnet 220 may be fixed by the fixing member 255, and the elastic member 220 is inserted into and coupled to an outer periphery of the fixing member 255, and one end of the guide hole 120 is closed by the plug member 257. Here, the plug member 257 and the fixing member 255 may be coupled to each other or formed integrally.

[0030] The magnet 220 may be a rare earth magnet made of, for example, neodymium or samarium and having a high magnetic flux density. This is because the cost can be reduced by minimizing the size of the magnet 220 because the magnet 220 is fixed at a location facing the Hall sensor 252. A general magnet, such as a ferrite magnet or an alnico magnet, which has a low magnetic flux density and is inexpensive, can be used as the magnet 220, so that the cost can be reduced. Then, even if a general magnet has a low magnetic flux density, a displacement of the magnetic flux is generated by a separate shielding member 230 while the magnet 220 and the Hall sensor 252 are fixed, so that the magnet 220 can be detected accurately and reliably.

[0031] The S pole of magnet 220 is located on the front side in correspondence with Hall sensor 252, and the N pole of magnet 220 is located on the back side. Therefore, if Hall sensor 252 is an N pole sensor or an opposite pole sensor, the present invention can be appropriately modified and corrected by those skilled in the art. In actual fields, S pole Hall sensors are most commonly used.

[0032] As described above, the actuating member 240 performs the function of moving the shielding member 230 when the pistons 111 and 112 are moved. Specifically, the actuating member 240 includes a plate 241 coupled to the first piston 111, and a rod 242 of a predetermined length coupled to the plate 241 and inserted into the guide hole 120 of the cylinder body 110.

[0033] The plate 241 is coupled to the first piston 111 on the front surface facing an output shaft (not illustrated), which displaces the first piston 111 with the pedal force of the brake pedal (not illustrated). The plate 241 includes a flange 241a arranged to be concentric with the first piston 111 and protruding in a radial direction of the piston 111, and a coupling part 241b bent from the flange 241a and inserted into and fixed to the inner side of the first piston 111. Then, a concave stopper recess 113 is formed on an inner side of the first piston 111, and a stopper step 243, which is inserted into the stopper recess 113, is formed on the coupling part 241b at a corresponding location.

[0034] The rod 242 may be integrally coupled to the flange 241a of the plate 241 such that it is arranged parallel to the first piston 111 in the longitudinal direction of the cylinder body 110 to cooperate with the first piston 111, or it may be provided with a support 259 at one end thereof to be supported by the plate 242, as shown in Fig. 6 is illustrated.

[0035] This means that the flange 241a can, as in Fig. 6, when the first piston 111 is actuated, the support 259 supports the rod to slide together with the first piston 111 and can return to the initial position through the elastic member 210.

[0036] The rod 242 has a predetermined length, and a portion of the rod 242 is inserted into the guide hole 120 of the cylinder body 110. The rod 242 may be formed integrally with the plate 241. One end of the rod 242 coupled to the plate 241 is coupled to the shielding member 230.

[0037] The shielding member 230 is slidably provided in the guide hole 120.

[0038] The shielding member 230 is moved by the actuating member 240 to perform a function of shielding the magnetic force generated between the magnet 220 and the Hall sensor 252, and may be formed of steel. Specifically, one end of the shielding member 230 is opened so that the magnet 220 is accommodated in the shielding member 230 when the magnet 220 is displaced by the rod 242. Although the shielding member 230 is illustrated as surrounding the magnet 220, the present invention is not limited to this, and the shielding member 230 may be provided in the form of a plate that is moved between the magnet 220 and the Hall sensor 252. Furthermore, although it has been described that the shield member 230 is coupled to the rod 242 of the operating member 240, the present invention is not limited to this, and the shield member 230 can be pushed and moved while being in contact with the rod 242.Accordingly, an elastic member 210, which returns the shield member 230 to the initial position, is provided on an opposite side of the shield member 230 in contact with the rod 242.

[0039] The elastic member 210 is provided in the guide hole 120 and elastically supports the shield member 230. One end of the elastic member 210 is supported by a ball member 125, and an opposite end thereof is supported by the shield member 230. The elastic member 210 includes a coil spring.

[0040] The Hall sensor assembly 250 is fixedly installed on an outer side of the cylinder body 110. The Hall sensor assembly 250 includes a sensor housing 251 in which a bracket (not illustrated) for coupling the assembly to the cylinder body 110 is formed, and a Hall sensor (a magnetic sensing element) 252 installed inside the sensor housing 251 to detect a change in magnetic flux density with the magnet 220 and control the turning on of the brake light. Then, the sensor housing 251 can be easily attached to and removed from the cylinder body 110 because it is coupled to an outer side of the cylinder body 110 by a bolt (not illustrated) or the like, and the Hall sensor 252 is installed to correspond to the location of the magnet 220.

[0041] As described above, the guide hole 120 is located at a space in the radial direction of the cylinder body 110, and the magnet 220 can be fixed to the guide hole 120, and the Hall sensor 252 can be installed at a location corresponding to the magnet 220 to minimize the size of the magnet. Furthermore, even if a general magnet such as a ferrite magnet or an alnico magnet, which is inexpensive, is used, high accuracy can be ensured.Since the master cylinder 100 can be used as long as the distance between the guide hole 120 and the Hall sensor 252 can withstand a vacuum pressure, although the master cylinder 100 should have a predetermined thickness for withstanding the fluid pressure generated in the master cylinder 100, the size of the magnet can be reduced by minimizing the distance between the Hall sensor 252 and the magnet 220, or high accuracy can be ensured even though a general magnet having a low magnetic flux density is used.

[0042] Hereinafter, an operating state of the BLS module due to an operation of the brake master cylinder having the above-described structure will be described with reference to the accompanying drawings.

[0043] First, when the driver depresses the brake pedal (not illustrated) to brake the vehicle, the first piston 111 of the master cylinder 100 advances according to a required pedal force from the booster or the pedal detection sensor. As the first piston 111 advances, the oil in the closed first fluid pressure chamber 111a is compressed, and the oil in the second fluid pressure chamber 112a is compressed, while the second piston 112 is moved in conjunction with the first piston 111. The first return spring 111b and the second return spring 112b, which are provided in front of the first piston 111 and the second piston 112, respectively, are compressed when a force is applied to the brake pedal, and when the force applied to the brake pedal is released, the first and second pistons 111 and 112 return to the initial positions by the elastic restoring force.

[0044] When the first and second pistons 111 and 112 move forward and backward, the Hall sensor assembly 250 installed outside the cylinder body 110 detects the movement of the first and second pistons 111 and 112. That is, when the first piston 111 moves forward, the plate 241 and the rod 242 coupled to the first piston 111 move together, and accordingly, the shielding member 230 disposed in the guide hole 120 moves. Then, the shielding member 230 shields a magnetic force, while the elastic member 210 is compressed and moves between the magnet 220 fixed to the guide hole 120 and the Hall sensor 252.

[0045] Accordingly, since a magnetic flux acting on the Hall sensor 252 that detects a magnetic flux is reduced, the Hall sensor assembly 250 that detects the reduced magnetic flux turns on the brake lamp.

[0046] In contrast, when the first and second pistons 111 and 112 return to their initial positions, that is, when the shielding member 230 opens a space between the Hall sensor 252 and the magnet 220, the brake light is turned off because the magnetic flux acting on the Hall sensor 252 increases. In particular, according to the embodiment of the present invention, since the magnetic flux density can be significantly increased by minimizing the distance between the magnet 220 and the Hall sensor 252, the size of the magnet can be minimized, and high accuracy can be ensured even though a general magnet is used.

[0047] Although the present invention has been described above in conjunction with the limited embodiments and drawings, the present invention is not limited thereto, and it is obvious that various modifications and changes can be made by those skilled in the art within the scope equivalent to the technical idea of ​​the present invention and the appended claims.

Claims

[1] Brake master cylinder (100), comprising a BLS module (200) for controlling the switching on of a brake light according to an actuation of a piston (111, 112) for controlling the switching on of a brake light according to an actuation of a piston (111, 112) which is intended to be moved back and forth within a cylinder body (110), in which the BLS module (200) comprises: a magnet (220) fixed to a guide hole (120) formed in the cylinder body (110) in a longitudinal direction of the cylinder body; an actuating member (240) coupled to the piston so as to be moved together with the piston (111) when the piston is moved; a Hall sensor (252) installed in the cylinder body (110) at a location corresponding to the magnet (220) for detecting a magnetic flux density of the magnet; and a shielding member (230) slidably provided in the guide hole and moved by the actuating member (240) for shielding the Hall sensor from the magnet (220). [2] The brake master cylinder according to claim 1, wherein the BLS module (200) further comprises an elastic member (210) provided in the guide hole (120) for elastically supporting the shield member (230). [3] A brake master cylinder according to claim 1 or 2, wherein one end of the shielding member (230) is opened so that the magnet (220) is accommodated in the shielding member when the shielding member (230) is moved by the operating member (240). [4] Brake master cylinder according to one of claims 1 to 3, wherein the actuating part (240) comprises: a plate (241) coupled to the piston (111); and a rod (242) having a predetermined length, one end of which is coupled to the plate (241) and an opposite end of which is inserted into the guide hole (120) to be coupled to the shielding member (230). [5] A brake master cylinder according to claim 4, wherein a ball member (125) for closing one end of the guide hole (120) is installed in the guide hole on the side opposite to the side on which the rod (242) is inserted. [6] A brake master cylinder according to claim 4 or 5, wherein a plug member (257) for closing one end of the guide hole (120) is coupled to the guide hole (120) on the side opposite to the side on which the rod (242) is inserted, and a fixing member (255) coupled or integrally formed with the plug member (257) for fixing the magnet is provided. [7] Brake master cylinder according to one of claims 1 to 3, wherein the actuating part (240) comprises: a plate (241) coupled to the piston (111); and a rod (242), one end of which is provided with a support (259) supported by the plate (241), and an opposite end of which is inserted into the guide hole (120) to be coupled to the shielding part (230), and wherein the plate (240) includes a flange (241a) arranged to be concentric with the piston (111) and projecting in a radial direction of the piston, and a coupling part (241b) bent from the flange (241a) and inserted into and fixed to the inner side of the piston (111), the flange (241a) supporting the support (259) for the sliding of the rod (242) when the piston is actuated. [8] Brake master cylinder according to one of claims 1 to 7, wherein the Hall sensor (252) is provided in the Hall sensor arrangement (250) and the Hall sensor arrangement (250) is coupled to the outside of the cylinder body (110).

Images