Apparatus and method for compensating braking force zero point of brake apparatus for vehicle

Abstract

The braking force zero point correction device of the vehicle brake device of the present invention is characterized by comprising: a load switch unit that outputs an electrical signal when a brake pad actually presses against a brake disc and a screw bar moves backward due to a repulsive force; a motor current measuring unit that measures the motor current of a motor that rotates the screw bar to press against the brake disc; and a control unit that estimates the estimated load applied to the screw bar during the process of operating the motor according to the motor current, and corrects the zero point of the estimated load based on the electrical signal.

Description

Technology Field

[0001] The present invention relates to a braking force zero-point correction device and method for a vehicle brake device, and more specifically, to a braking force zero-point correction device and method for a vehicle brake device that corrects the estimated time of load occurrence by motor current using the actual time of load occurrence on the brake pad of the vehicle brake device. Background Technology

[0002] Generally, an automobile's electromechanical brake (EMB) converts the rotational force of a drive motor into linear motion using a screw and nut mechanism to pressurize a piston. The pressurized piston compresses the brake pad, which acts as a friction material, against the wheel disc, thereby generating braking force.

[0003] Conventional electromechanical brakes for vehicles generate a load by pushing the brake pads in a straight line through mechanical conversion of rotation achieved by controlling the motor's current.

[0004] However, conventional electromechanical brakes for vehicles had the problem that it was impossible to estimate the position for actual braking force generation and release tests using only control information applied to the motor, and it was impossible to estimate the actual braking force during the driver's braking process using only load switch operation.

[0005] The background technology for the present invention is disclosed in Korean Registered Patent Publication No. 10-0456779 (Title of invention: Brake device for automobile, Registration date: April 29, 2004). The problem to be solved

[0006] The present invention was created out of the aforementioned necessity, and the objective according to one aspect of the present invention is to provide a braking force zero-point correction device and method for a vehicle brake device that corrects the estimated time of load generation by motor current using the actual time of load generation on the brake pad of the vehicle brake device. means of solving the problem

[0007] A braking force zero point correction device for a vehicle brake device according to one aspect of the present invention is characterized by comprising: a load switch unit that outputs an electrical signal when a brake pad actually presses against a brake disc and a screw bar moves backward due to a repulsive force; a motor current measuring unit that measures the motor current of a motor that rotates the screw bar so that the brake pad presses against the brake disc; and a control unit that estimates the estimated load applied to the screw bar during the process of operating the motor according to the motor current, and corrects the zero point of the estimated load based on the electrical signal.

[0008] The control unit of the present invention is characterized by correcting the zero point of the estimated load based on the estimated load estimated at the time when the electrical signal is input.

[0009] The control unit of the present invention is characterized by correcting the estimated load at the time when the electrical signal is input to 0 if the estimated load is not 0 at the time when the electrical signal is input.

[0010] The control unit of the present invention is characterized by correcting the entire estimated load for each motor current based on the corrected zero point at the time when the electrical signal is input.

[0011] The control unit of the present invention is characterized by determining that a failure has occurred in the motor current monitoring function of the motor current measuring unit if the estimated load remains at 0 for a set time or longer after the electrical signal is input.

[0012] A method for correcting the zero point of a braking force of a vehicle brake device according to one aspect of the present invention comprises: a step in which, when a motor rotates a screw bar so that a brake pad presses against a brake disc, a motor current measuring unit measures the motor current of the motor, and a control unit estimates the load applied to the screw bar according to the motor current of the motor measured by the motor current measuring unit; a step in which, when the brake pad actually presses against the brake disc and the screw bar moves backward due to a repulsive force, a load switch unit outputs an electrical signal; and a step in which, when the electrical signal is input from the load switch, the control unit corrects the zero point of the estimated load based on the time at which the electrical signal is input.

[0013] The step of correcting the zero point of the estimated load according to the present invention is characterized by correcting the zero point of the estimated load based on the estimated load estimated at the time when the electrical signal is input.

[0014] The step of correcting the zero point of the estimated load of the present invention is characterized by correcting the estimated load at the time when the electrical signal is input to zero if the estimated load is not zero at the time when the electrical signal is input.

[0015] The step of correcting the zero point of the estimated load according to the present invention is characterized in that the control unit corrects the entire estimated load for each motor current based on the corrected zero point at the time when the electrical signal is input.

[0016] The present invention is characterized by further including a step in which the control unit determines that a failure has occurred in the motor current monitoring function of the motor current measuring unit if the estimated load remains at 0 for a set time or longer after the electrical signal is input. Effects of the invention

[0017] The braking force zero-point correction device and method for a vehicle brake device according to the present invention can reduce initial ineffectiveness and improve precision when calculating output load by correcting the estimated time of load generation by motor current using the actual time of load generation for the brake pad of the vehicle brake device. Brief explanation of the drawing

[0018] FIG. 1 is a perspective view of a vehicle brake device according to one embodiment of the present invention. Figure 2 is a cross-sectional view of AA' of Figure 1. Figure 3 is an enlarged view of part A of Figure 2. FIG. 4 is a half-sectional perspective view of a vehicle brake device according to one embodiment of the present invention. FIG. 5 is an exploded perspective view of a key part of a vehicle brake device according to one embodiment of the present invention. FIG. 6 is a perspective view showing a load switch portion of a vehicle brake device according to one embodiment of the present invention. FIG. 7 is an exploded view of the load switch portion of a vehicle brake device according to one embodiment of the present invention. Fig. 8 is a perspective view of Fig. 7 seen from a different direction. FIG. 9 is a diagram showing the load switch portion of a vehicle brake device operating during braking according to one embodiment of the present invention. Figure 10 is an enlarged view of part B of Figure 9. FIG. 11 is a block diagram of a braking force zero-point correction device for a vehicle brake device according to one embodiment of the present invention. FIG. 12 is a flowchart of a braking force zero-point correction device for a vehicle brake device according to one embodiment of the present invention. Specific details for implementing the invention

[0019] Hereinafter, a braking force zero-point correction device and method for a vehicle brake device according to an embodiment of the present invention will be described in detail with reference to the attached drawings. In this process, the thickness of lines or the size of components shown in the drawings may be exaggerated for clarity and convenience of explanation. Furthermore, the terms described below are defined considering their functions in the present invention, and these may vary depending on the intention or convention of the user or operator. Therefore, the definitions of these terms should be based on the content throughout this specification.

[0020] FIG. 1 is a perspective view of a vehicle brake device according to an embodiment of the present invention, FIG. 2 is a cross-sectional view of AA' of FIG. 1, FIG. 3 is an enlarged view of part A of FIG. 2, FIG. 4 is a half-sectional perspective view of a vehicle brake device according to an embodiment of the present invention, FIG. 5 is an exploded perspective view of a key part of a vehicle brake device according to an embodiment of the present invention, FIG. 6 is a perspective view showing a load switch part of a vehicle brake device according to an embodiment of the present invention, FIG. 7 is an exploded perspective view of a load switch part of a vehicle brake device according to an embodiment of the present invention, FIG. 8 is a perspective view of FIG. 7 viewed from a different direction, FIG. 9 is a diagram showing the load switch part operating during braking of a vehicle brake device according to an embodiment of the present invention, and FIG. 10 is an enlarged view of part B of FIG. 9.

[0021] Referring to FIGS. 1 through 10, a vehicle brake device (1) according to one embodiment of the present invention comprises a caliper body (100), a pair of brake pads (200), a screw bar (300), a nut part (400), a piston part (500), a bearing part (600), a load switch part (700), and a control part (800) (shown in FIG. 11). The caliper body (100) encloses a brake disc (10). The caliper body (100) comprises a first caliper body (110) and a second caliper body (120). The first caliper body (110) is equipped with a screw bar (300), a nut part (400), a piston part (500), a bearing part (600), a load switch part (700), and a motor part (900) (shown in FIG. 11). The second caliper body (120) is connected to the first caliper body (110), and a pair of brake pads (200) are mounted facing each other.

[0022] A pair of brake pads (200) are positioned facing each other on the caliper body (100) and are each located on both sides of the brake disc (10). Specifically, the brake pad (200) includes a back plate (210) and a friction member (220). The back plate (210) is positioned facing the piston part (500) described later and is pressed by the piston part (500).

[0023] The friction member (220) is coupled to the surface of the back plate (210) facing the brake disc (20). The friction member (220) can contact the brake disc (10).

[0024] The screw bar (300) is installed on the caliper body (100) and is rotatable by the power of the motor unit (900). The screw bar (300) is inserted into the nut unit (400) described later in a rod shape, is provided with male screw threads (not shown) on the outer side, and rotates by receiving rotational force from the motor unit (900) described later.

[0025] The motor unit (900) transmits power to the screw bar (300). The motor unit (900) is equipped with a motor (910) and a gear module unit (920). The gear module unit (920) is equipped with a plurality of gears (910), and one of the plurality of gears is connected to the motor (910) and the other is connected to the screw bar (300). That is, the gear module unit (920) receives rotational force from the motor (910) and rotates the screw bar (300).

[0026] The nut portion (400) moves linearly by the rotation of the screw bar (300). The nut portion (400) surrounds the outer side of the screw bar (300) and, depending on the rotation direction of the screw bar (300), is selectively moved toward the brake pad (200) or toward the opposite side of the brake pad (200).

[0027] Specifically, when the screw bar (300) is rotated in the set direction, the nut portion (400) converts the rotational motion of the screw bar (300) into linear motion and moves toward the brake pad (200). Conversely, when the screw bar (300) is rotated in the opposite direction to the set direction, the nut portion (400) moves toward the opposite side of the brake pad (200).

[0028] The piston portion (500) is installed in a shape that surrounds the outer side of the nut portion (400) and moves together with the nut portion (400) to press one of the pair of brake pads (200). The piston portion (500) is formed in a cylindrical shape, the direction in which the nut portion (400) is inserted is open, and the portion facing the brake pad (200) is shielded.

[0029] The piston portion (500) moves together with the nut portion (400), and applies pressure to the brake pad (200) by the pressure of the nut portion (400), or releases the pressure applied to the brake pad (200) by releasing the pressure of the nut portion (400). The piston portion (500) is moved toward the brake pad (200) or to the opposite side of the brake pad (200) by the pressure of the nut portion (400).

[0030] When the piston part (500) presses the brake pad (200), the brake pad (200) comes into contact with the brake disc (20) and generates braking force. That is, when the piston part (500) presses the back plate (210) of the brake pad (200), the friction member (220) of the brake pad (200) comes into contact with the brake disc (20).

[0031] The bearing section (600) supports the rotation of the screw bar (300) as a thrust bearing and moves by the repulsive force of the screw bar (300). Specifically, when the piston section (500) is in close contact with the brake pad (200) and presses the brake pad (200), a repulsive force is applied to the screw bar (300), causing it to move backward. As a result, the bearing section (600) moves backward and presses the load switch section (700). That is, the control section (800) described later becomes capable of measuring the point in time when the braking force is generated.

[0032] The load switch unit (700) is installed on the caliper body (100), is positioned facing the bearing unit (600), and is operated by the pressure of the bearing unit (600).

[0033] The load switch section (700) includes a housing section (710), a moving block section (720), and a connector section (730). The housing section (710) is installed on the first caliper body (110) of the caliper body (100). The housing section (710) has a ring-shaped installation hole section (711) formed therein, into which the moving block section (720), described later, is installed. The housing section (710) has a passage hole section (712) formed in the center through which a screw bar (300) passes.

[0034] The moving block (720) is installed in the housing (710) and moves by the pressure of the bearing (600), and returns to its original position by the elastic restoring force when the pressure of the bearing (600) is released. When the bearing (600) moves and pressurizes the moving block (720) due to the repulsive force of the screw (300), it moves backward and comes into contact with the connector (730) described later. At this time, the point in time when the repulsive force of the screw (300) is generated is the point in time when the piston (500) is in close contact with the brake pad (200) and pressurizes the brake pad (200) to generate braking force.

[0035] Subsequently, when the piston part (500) releases pressure on the brake pad (200) and the braking force is released, the bearing part (600) releases pressure on the movable block part (720), and the bearing part (600) returns to its original position by the elastic restoring force of the elastic member (722) described later. At this time, the braking force is released.

[0036] The movable block portion (720) protrudes outward from the housing portion (710). As a result, when the bearing portion (600) moves due to the repulsive force of the screw bar (300), the movable block portion (720) can be pressed.

[0037] The movable block portion (720) includes a movable block (721) and an elastic member (722). The movable block (721) is movably positioned on the housing portion (710) and comes into contact with the connector portion (730).

[0038] The movable block (721) includes a movable block body (721a) and a conductor plate (721d). The movable block body (721a) is elastically supported by an elastic member (722). The movable block body (721a) includes a first movable block body (721b) and a second movable block body (721c). The first movable block body (721b) is movably positioned in the installation hole (711) of the housing part (710). The second movable block body (721c) is connected to the first movable block body (721b), and a conductor plate (721d), described later, is installed on one side.

[0039] The conductor plate (721d) is installed on the movable block body (721a) and comes into contact with the contact portion (732). The conductor plate (721d) is installed on the second movable block body (721c) of the movable block body (721a) and comes into contact with the connector portion (730) during the movement of the movable block (721).

[0040] The elastic member (722) is connected to the movable block (721) by a spring and coupled with the connector part (730), and elastically supports the movable block (721). As a result, when the pressure of the bearing part (600) on the movable block (721) is released, the movable block (721) can return to its original position.

[0041] The connector part (730) comes into contact with the moving block part (720) when the moving block part (720) moves, and transmits an electrical signal to the control part (800).

[0042] The connector section (730) includes a connector body (731) and a contact section (732). An elastic member (722) is coupled to the connector body (731). The connector body (731) includes a first connector body (731a), a coupling plate (731b), and a second connector body (731c). A contact section (732), described later, is installed in the first connector body (731a). The coupling plate (731b) is connected to the first connector body (731a) and has an elastic member (722) coupled to it. The second connector body (731c) is connected to the coupling plate (731b) in a tubular shape and surrounds the contact section (732).

[0043] The contact portion (732) is mounted on the connector body (731) and generates an electrical signal upon contact with the movable block (721). Multiple contact portions (732) are mounted spaced apart from each other on the first connector body (731a) of the connector body (731).

[0044] The contact portion (732) includes a contact projection (732a) and a terminal (732b). The contact projection (732a) is mounted on the connector body (731) and contacts the conductor plate (721d). Multiple contact projections (732a) are mounted spaced apart from each other on the first connector body (731a) of the connector body (731).

[0045] The terminal (732b) is connected to the contact projection (732a), and when the conductor plate (721d) contacts the contact projection (732a), the electrical signal generated between the contact projection (732a) and the conductor plate (721d) is transmitted to the control unit (800) described later. The terminal (732b) is connected to the contact projection (732a) in multiple numbers. The second connector body (731c) of the connector body (731) surrounds the outer side of the terminal (732b).

[0046] The control unit (800) receives an electrical signal from the load switch unit (700) and controls the operation of the motor unit (900) based on the electrical signal. Specifically, the control unit (800) can predict the timing of braking force generation based on the electrical signal received from the load switch unit (700).

[0047] Conversely, the control unit (800) can predict the braking force release time if it does not receive an electrical signal from the load switch unit (700). The control unit (800) can predict the braking force generation time and the braking force release time and control the operation of the motor unit (900) to correct the position of the screw bar (300).

[0048] At this time, instead of always returning the position of the screw bar (300) to the initial point of braking force generation, the initial point of operation is reset and returned based on the point of braking force release, thereby reducing the initial ineffectiveness, i.e., the ineffective stroke. Furthermore, as the initial point of operation of the screw bar (300) is reset due to wear of the brake pad (200), the ineffective stroke during the next braking can be reduced.

[0049] Hereinafter, with reference to FIGS. 2, FIGS. 3, FIGS. 9, and FIGS. 10, we will examine the operation and effects of a vehicle brake device according to an embodiment of the present invention.

[0050] When braking, the screw bar (300) is rotated in a set direction by the power of the motor unit (900). When the screw bar (300) is rotated in the set direction, the nut unit (400) and the piston unit (500) move toward the brake pad (200), and the piston unit (500) presses the brake pad (200).

[0051] The brake pad (200) comes into contact with the brake disc (10) and a braking force is generated. At this time, the piston part (500) presses the brake pad (200), causing a repulsive force to be generated in the piston part (500) and the nut part (400), and also in the screw bar (300).

[0052] The bearing part (600) moves backward due to the repulsive force of the screw bar (300), and the load switch part (700) is activated as the bearing part (600) presses the load switch part (700). That is, the load switch part (700) is activated by the load of the bearing part (600).

[0053] The load switch unit (700) transmits an electrical signal to the control unit (800), and the control unit (800) predicts the timing of braking force generation based on the electrical signal received from the load switch unit (700) and can display this on the monitor unit (not shown).

[0054] Subsequently, when the brake is released, if the screw bar (300) rotates in the opposite direction of the set direction by the power of the motor part (900), the nut part (400) and the piston part (500) move to the opposite side of the brake pad (200), and the pressure on the brake pad (200) is released.

[0055] When the pressure of the brake pad (200) is released, the bearing part (600) returns to its original position, the bearing part (600) stops pressing the load switch part (700), and the operation of the load switch part (700) stops.

[0056] The load switch unit (700) does not transmit an electrical signal to the control unit (800), and the control unit (800) can predict the time of release of the braking force and display it on the monitor unit (not shown).

[0057] In this way, the control unit (800) predicts the braking force generation time and the braking force release time through the load switch unit (700), and based on this, controls the operation of the motor unit (900) to correct the position of the screw bar (300).

[0058] The control unit (800) operates the motor unit (900) so that the position of the screw bar (300) is not always returned to the initial point of braking force generation, but rather resets and returns the initial point of operation based on the point of braking force release. As a result, the initial ineffectiveness, i.e., the ineffective stroke, can be reduced. In addition, as the initial point of operation of the screw bar (300) is reset due to wear of the brake pad (200), the ineffective stroke during the next braking can be reduced.

[0059] FIG. 11 is a block diagram of a braking force zero-point correction device for a vehicle brake device according to one embodiment of the present invention.

[0060] Referring to FIG. 11, a braking force zero point correction device for a vehicle brake device according to one embodiment of the present invention includes a load switch unit (700), a control unit (800), a motor unit (900), a motor current measuring unit (1000), and an output unit (1100).

[0061] Here, the load switch unit (700) and the motor unit (900) are identical to the above-described embodiment, so their detailed description is omitted here.

[0062] The motor current measuring unit (1000) measures the motor current according to the driving of the motor (910) and inputs the measured motor current to the control unit (800).

[0063] The output unit (1100) outputs the motor current monitoring results. For example, if the motor current monitoring function is determined to be faulty by the control unit (800), the output unit (1100) provides information on the motor current monitoring function failure via video or audio according to the control signal of the control unit (800). At this time, passengers, etc., can recognize the corresponding function failure.

[0064] The output section (1100) may be a vehicle cluster (not shown), but is not specifically limited.

[0065] The control unit (800) operates the motor (910) to rotate the screw bar (300). As the screw bar (300) rotates by the power of the motor unit (900), the nut unit (400) moves in a straight line. Depending on the direction of rotation of the screw bar (300), the nut unit (400) moves toward the brake pad (200) or to the opposite side of the brake pad (200) to apply pressure to or release pressure on the brake pad (200).

[0066] The control unit (800) receives an electrical signal from the load switch unit (700) and can control the operation of the motor unit (900) based on this electrical signal.

[0067] At this time, the control unit (800) receives the motor current measured by the motor current measuring unit (1000) and estimates the load of the bearing unit (600) based on this motor current.

[0068] The control unit (800) can detect the estimated load expected to be applied to the screw bar (300) for each motor current by storing the load for each motor current in a lookup table format or by calculating the load based on the motor current.

[0069] The method of estimating the load of the bearing part (600) based on the motor current is not particularly limited.

[0070] Meanwhile, the control unit (800) receives an electrical signal from the load switch unit (700) as described above, depending on the operation of the motor unit (900).

[0071] That is, when braking, if the screw bar (300) rotates in the set direction by the power of the motor part (900), the nut part (400) and the piston part (500) move toward the brake pad (200), thereby causing the piston part (500) to press the brake pad (200).

[0072] As the brake pad (200) comes into contact with the brake disc (10), a braking force is generated. As the piston part (500) presses the brake pad (200), a repulsive force is generated in the piston part (500) and the nut part (400), and a repulsive force is also generated in the screw bar (300).

[0073] Due to the repulsive force of the screw bar (300), the bearing part (600) moves backward, and as the bearing part (600) presses the load switch part (700), the load switch part (700) operates and inputs an electrical signal to the control part (800). In this way, when an actual load is generated by the operation of the motor part (900), an electrical signal is input to the control part (800).

[0074] Accordingly, the control unit (800) can correct the zero point of the estimated load and the origin of the braking force based on the motor current, based on the electrical signal input from the load switch unit (700) due to the actual load generation. That is, the control unit (800) performs zero point correction for the initial braking force when braking force is generated through the control of the actual motor (910).

[0075] The point in time when the electrical signal input from the load switch unit (700) is input is the point in time when the actual load is generated. The control unit (800) can correct the zero point of the current estimated by the motor current by correcting the estimated load, estimated based on the motor current, to zero at the point in time when the electrical signal is input from the load switch unit (700). Through this, the control unit (800) performs zero point correction for the initial braking force when braking force is generated through the control of the actual motor (910).

[0076] For example, when the control unit (800) applies current to the motor and the motor operates, the motor current is measured by the motor current measuring unit (1000).

[0077] At this time, the control unit (800) estimates the load based on the measured motor current, and the estimated load may be greater than 0.

[0078] However, if an electrical signal is input from the load switch unit (700) during this process, the point in time when the electrical signal is input is the point in time when the load is actually generated, so it can be seen that the load estimated by the motor current is inaccurate.

[0079] Accordingly, the control unit (800) zeros out the estimated load by the motor current to 0 when the estimated load is greater than 0 at the time when an electrical signal is input from the load switch.

[0080] Furthermore, the control unit (800) can correct the entire estimated load per motor current by correcting a lookup table or calculation formula for estimating the load through the motor current.

[0081] The magnitude of the estimated load at the time when the electrical signal is input can be considered an error. For example, the control unit (800) can correct the total estimated load for each motor current by subtracting the estimated load (error) at the time when the electrical signal is input from each estimated load in the lookup table.

[0082] Meanwhile, the control unit (800) determines that a failure has occurred in the motor current monitoring function of the motor current measuring unit (1000) when an electrical signal is input from the load switch unit (700) and the estimated load based on the current motor current remains at 0 for a set time or longer while the electrical signal exceeds 0.

[0083] Typically, motor driving and piston movement by motor current precede the circuit closing of the load switch (700).

[0084] Accordingly, the control unit (800) determines that the motor current monitoring function is faulty if the estimated load based on the motor current remains 0 even when an electric signal is input from the load switch unit (700) (when the electric signal is greater than 0), and outputs this through the output unit (1100).

[0085] At this time, the output unit (110) can warn of a motor current monitoring function failure via video or voice.

[0086] Hereinafter, a method for zero-point correction of braking force of a vehicle brake device according to one embodiment of the present invention will be described in detail with reference to FIG. 12.

[0087] FIG. 12 is a flowchart of a braking force zero-point correction device for a vehicle brake device according to one embodiment of the present invention.

[0088] Referring to FIG. 12, the control unit (800) operates the motor (910) (S100).

[0089] As the motor unit (900) operates, the motor current measuring unit (200) measures the motor current of the motor (910) and inputs it to the control unit (800).

[0090] The control unit (800) estimates the load according to the motor current input from the motor current measuring unit (200) (S300).

[0091] Additionally, as the motor part (900) operates, the screw bar (300) rotates by the power of the motor part (900), causing the nut part (400) to move in a straight line.

[0092] That is, when braking, if the screw bar (300) rotates in the set direction by the power of the motor part (900), the nut part (400) and the piston part (500) move toward the brake pad (200), thereby causing the piston part (500) to press the brake pad (200).

[0093] As the brake pad (200) comes into contact with the brake disc (10), a braking force is generated. As the piston part (500) presses the brake pad (200), a repulsive force is generated in the piston part (500) and the nut part (400), and a repulsive force is also generated in the screw bar (300).

[0094] Due to the repulsive force of the screw bar (300), the bearing part (600) moves backward, and as the bearing part (600) presses the load switch part (700), the load switch part (700) operates and inputs an electrical signal to the control part (800).

[0095] Accordingly, the control unit (800) checks whether an electrical signal is input from the load switch unit (700) (S400), and if an electrical signal is input, checks whether the estimated load estimated as described above is 0 (S500).

[0096] If the estimated load is 0 as a result of the verification at step S500, the control unit (800) determines whether the estimated load remains 0 for a set time or longer (S600).

[0097] If the estimated load remains at zero as a result of the judgment in step S600, the control unit (800) determines the motor current monitoring function as faulty and outputs the judgment result through the output unit (110) (S700).

[0098] If the estimated load does not remain at zero as a result of the judgment in step S610, or if the estimated load changes, the control unit (800) determines that the estimated load is normal.

[0099] On the other hand, if the estimated load is not zero as a result of verification at step S500, the control unit (800) zero-points the estimated load based on the motor current to zero at the time when an electrical signal is input from the load switch unit (700) (S800).

[0100] In addition, the control unit (800) can correct the entire estimated load for each motor current by correcting a lookup table or calculation formula for estimating the load through the motor current (S900).

[0101] As such, the braking force zero-point correction device and method for a vehicle brake device according to one embodiment of the present invention can reduce initial ineffectiveness and improve precision when calculating output load by correcting the estimated time of load generation by motor current using the actual time of load generation on the brake pad of the vehicle brake device.

[0102] The implementations described herein may be implemented, for example, as methods or processes, devices, software programs, data streams, or signals. Even if discussed only in the context of a single form of implementation (e.g., discussed only as a method), the implementation of the discussed features may also be implemented in other forms (e.g., devices or programs). Devices may be implemented in appropriate hardware, software, and firmware, etc. Methods may be implemented in devices such as processors, which generally refer to processing devices including, for example, computers, microprocessors, integrated circuits, or programmable logic devices. Processors also include communication devices such as computers, cell phones, portable / personal digital assistants ("PDAs"), and other devices that facilitate the communication of information between end-users.

[0103] Although the present invention has been described with reference to the embodiments illustrated in the drawings, this is merely illustrative and those skilled in the art will understand that various modifications and equivalent alternative embodiments are possible therefrom. Accordingly, the true technical scope of protection of the present invention should be determined by the claims below. Explanation of the symbols

[0104] 1 : Vehicle brake system 10 : Brake disc 100 : Caliper body 110 : 1st caliper body 120: 2nd caliper body 200: Brake pad 210 : Backplate 220 : Friction member 300 : Screw bar 400 : Nut part 500 : Piston part 600 : Bearing part 700 : Load switch section 710 : Housing section 711: Installation hole 712: Pass-through hole 720 : Moving block section 721 : Moving block 721a : Moving block main body 721b : First moving block main body 721c: Second movable block main body 721d: Conductor plate 722 : Elastic member 730 : Connector part 800: Control unit 900: Motor unit 910: Motor 910: Gear Module 1000: Motor current measurement unit 1100: Output unit

Claims

Claim 1 A braking force zero point correction device for a vehicle brake device comprising: a load switch unit that outputs an electrical signal when a brake pad actually presses against a brake disc and a screw bar moves backward due to a repulsive force; a motor current measuring unit that measures the motor current of a motor that rotates the screw bar so that the brake pad presses against the brake disc; and a control unit that estimates the estimated load applied to the screw bar during the process of operating the motor according to the motor current, and corrects the zero point of the estimated load based on the electrical signal. Claim 2 A braking force zero point correction device for a vehicle brake device according to claim 1, wherein the control unit corrects the zero point of the estimated load based on the estimated load estimated at the time when the electrical signal is input. Claim 3 A braking force zero-point correction device for a vehicle brake device according to claim 2, wherein the control unit corrects the estimated load at the time when the electrical signal is input to zero if the estimated load is not zero at the time when the electrical signal is input. Claim 4 A braking force zero point correction device for a vehicle brake device according to claim 1, wherein the control unit corrects the entire estimated load for each motor current based on the zero point corrected at the time when the electrical signal is input. Claim 5 A braking force zero-point correction device for a vehicle brake device according to claim 1, characterized in that the control unit determines that a failure has occurred in the motor current monitoring function of the motor current measuring unit if the estimated load remains at zero for a set time or longer after the electrical signal is input. Claim 6 A method for correcting the zero point of a braking force of a vehicle brake device, comprising: a step in which a motor rotates a screw bar so that a brake pad presses against a brake disc, a motor current measuring unit measures the motor current of the motor, and a control unit detects an estimated load that is estimated to be applied to the screw bar according to the motor current of the motor measured by the motor current measuring unit; a step in which, when the brake pad actually presses against the brake disc and the screw bar moves backward due to a repulsive force, a load switch unit outputs an electrical signal; and a step in which, when the electrical signal is input from the load switch, the control unit corrects the zero point of the estimated load based on the time at which the electrical signal is input. Claim 7 A method for correcting the zero point of a braking force of a vehicle brake device according to claim 6, wherein the step of correcting the zero point of the estimated load is characterized by correcting the zero point of the estimated load based on the estimated load estimated at the time when the electrical signal is input. Claim 8 A method for correcting the zero point of a braking force of a vehicle brake device according to claim 7, wherein the step of correcting the zero point of the estimated load is characterized by correcting the estimated load at the time when the electrical signal is input to zero if the estimated load is not zero at the time when the electrical signal is input. Claim 9 In claim 6, the step of correcting the zero point of the estimated load is characterized in that the control unit corrects the entire estimated load for each motor current based on the corrected zero point at the time when the electrical signal is input. Claim 10 A method for zero-point correction of braking force of a vehicle brake device according to claim 6, further comprising the step of determining that a failure has occurred in the motor current monitoring function of the motor current measuring unit if the estimated load remains at zero for a set time or longer after the electrical signal is input.

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