BRAKE ACTUATOR

Abstract

Brake actuating device (100) which is arranged to push or release a piston (30) towards a brake pad and is controlled by an electrical signal, the brake actuating device comprising: a force generating part (110) provided for generating a force by an electrical signal; a spindle member (120) adapted to rotate by receiving a force from the force generating member (110) and having a first screw portion (121a) formed on an outer peripheral surface; and a nut member (130) provided for pressing or releasing the piston (30), the nut member (130) having a second screw portion (131a) formed on an inner peripheral surface to engage with the first screw portion (121a), wherein the size of the pitch of the second screw portion (131a) is constant, characterized in that a size of a pitch between adjacent threads of the first screw portion (121a) changes in a constant cycle along a rotational direction, wherein the size of the pitch of the first screw portion (121a) changes cyclically, so that a load exerted on the force generating part (110) connected to the spindle element (120) during rotation of the spindle element (120) changes cyclically.

Description

field of technology

[0001] The present disclosure relates to a brake operating device and, more particularly, to a brake operating device capable of performing precise control in an electronic caliper brake. Technical background

[0002] A braking system is essential for decelerating a vehicle, and recently an electronic caliper brake has been proposed for parking braking, which uses a brake actuation device in addition to a hydraulic disc brake.

[0003] The electronic caliper brake includes a disc that rotates with a wheel of a vehicle, a carrier on which a pair of brake pad plates are installed so that they can be moved forward and backward to press the disc, a caliper housing slidably installed on the carrier, a cylinder provided in the caliper housing, a piston installed in the cylinder so that it can be moved forward and backward by hydraulic brake pressure, a spindle member and a nut member for pressing the piston, and an actuator for transmitting a driving force to the spindle member.

[0004] Such an electronic caliper brake performs hydraulic braking by pressing the piston with the hydraulic brake pressure, or it performs parking braking by receiving a driving force from a power transmission part of the actuator and pressing the piston through a power conversion part.

[0005] In particular, during a braking operation, the actuator controls the current supplied to the actuator. In this case, a conventional electronic caliper brake only controls the current to determine whether the actuator is actuated or stopped. RevelationTechnical task

[0006] The present disclosure aims to provide a brake actuator capable of detecting the rotational speed or torque of a spindle member during braking without a separate sensor.

[0007] The present disclosure aims to provide a brake operating device capable of performing precise control without affecting the assembly and productivity of the product by changing only a part of the structure of a spindle or nut member.

[0008] The present disclosure aims to provide a brake operating device capable of improving efficiency by adjusting a supply current depending on a temperature condition of a power generating part or a motor.

[0009] Document DE 10 2019 202 219 A1 relates to an electric caliper brake with a power transmission module including a spindle part installed to pass through a rear portion of the cylinder and configured to receive rotational force from an actuator to rotate, and a nut part threadably coupled to the spindle part, disposed in the piston, and configured to be moved forward or backward according to the rotation of the spindle part to actuate the piston. The spindle part includes a first screw thread portion corresponding to a screw thread formed on the nut part, and a second screw thread portion arranged to have the same axis as the first screw thread portion and having a thread pitch different from that of the first screw thread portion.As the nut member rotates around the second screw thread portion, a frictional force between the screw thread of the nut member and the second screw thread increases. Document KR 20 0 426 314 Y1 relates to a self-locking screw and discloses that the pitch of the screw changes from one end to the other and that protrusions are formed on the screw thread at regular intervals. DE 10 2013 008 673 A1 relates to an electromechanical parking brake and discloses a position detection unit, such as a Hall sensor or a switch, for detecting the relative position of the pitch of the spindle member with respect to the nut member. Technical solution

[0010] The present invention is defined in the independent claims. Specific embodiments are set forth in the dependent claims.

[0011] One aspect of the present disclosure provides a brake operating device configured to push or release a piston toward a brake pad and controlled by an electrical signal, comprising a force generating part configured to generate a force by an electrical signal, a spindle member configured to rotate by receiving force from the force generating part and having a first screw portion formed on an outer peripheral surface, and a nut member configured to push or release the piston, the nut member having a second screw portion formed on an inner peripheral surface to engage with the first screw portion, wherein a size of a pitch between adjacent threads of the first screw portion is changed in a constant cycle along a rotation direction.The size of the pitch of the second screw portion is constant, while the size of the pitch of the first screw portion changes cyclically, so that a load exerted on the force generating part connected to the spindle element during rotation of the spindle element changes cyclically.

[0012] The first screw portion may have a first pitch between the threads on one side and a second pitch between the threads on the other side, and a size (X+α) of the second pitch may be larger than a size (X) of the first pitch.

[0013] The first pitch may be formed on the opposite side of the second pitch with respect to the central axis of the spindle element.

[0014] The nut member may include a rod member in which the second screw portion is formed, and a head formed to extend radially from the rod member and provided with an anti-rotation part corresponding to an anti-rotation surface of the piston.

[0015] Another aspect of the present disclosure provides a brake operating device configured to push or release a piston toward a brake pad and controlled by an electrical signal, comprising a force generating part configured to generate a force or power by an electrical signal, a spindle member configured to rotate by receiving force from the force generating part and having a first screw portion formed on an outer peripheral surface, and a nut member configured to push or release the piston, the nut member having a second screw portion formed on an inner peripheral surface to engage with the first screw portion, wherein a size of a pitch between adjacent threads of the second screw portion is changed in a constant cycle along a rotation direction.The size of the pitch of the first screw portion is constant, while the size of the pitch of the second screw portion changes cyclically, so that a load exerted on the force generating part connected to the spindle element during rotation of the spindle element changes cyclically.

[0016] The second screw portion may have a first pitch between the threads on one side and a second pitch between the threads on the other side, and a size (X+α) of the second pitch may be larger than a size (X) of the first pitch.

[0017] The first pitch may be formed on the opposite side of the second pitch with respect to the central axis of the nut member.

[0018] The nut member may include a rod member in which the second screw portion is formed, and a head formed to extend radially from the rod member and provided with an anti-rotation part corresponding to an anti-rotation surface of the piston.

[0019] Another aspect of the present disclosure provides a brake operating device configured to push or release a piston toward a brake pad and controlled by an electrical signal, comprising a force generating part configured to generate a force by an electrical signal, a spindle member configured to rotate by receiving force from the force generating part and having a first screw portion formed on an outer peripheral surface, and a nut member configured to push or release the piston, wherein the nut member has a second screw portion formed on an inner peripheral surface to engage with the first screw portion, wherein the first screw portion has a plurality of projections configured tothat they project onto grooves between threads in a constant cycle along a rotational direction. When the spindle element and the nut element mesh and are rotated, the projection generates a load by cyclically gripping the nut element.

[0020] The projections may be shaped to protrude in a cycle of one revolution along the direction of rotation.

[0021] A size of a pitch between the adjacent threads of the second screw portion may be formed to be constant.

[0022] The nut member may include a rod member in which the second screw portion is formed, and a head formed to extend radially from the rod member and provided with an anti-rotation part corresponding to an anti-rotation surface of the piston.

[0023] Another aspect of the present disclosure provides a brake operating device configured to push or release a piston toward a brake pad and controlled by an electrical signal, comprising a force generating part configured to generate a force by an electrical signal, a spindle member configured to rotate by receiving force from the force generating part and having a first screw portion formed on an outer peripheral surface, and a nut member configured to push or release the piston, wherein the nut member has a second screw portion formed on an inner peripheral surface to engage with the first screw portion, wherein the second screw portion has a plurality of projections configured tothat they project onto grooves between threads in a constant cycle along a rotational direction. When the spindle element and the nut element mesh and are rotated, the projection generates a load by being cyclically held against the spindle element.

[0024] The projections may be shaped to protrude in a cycle of one revolution along the direction of rotation.

[0025] A size of a pitch between the adjacent threads of the first screw section may be formed to be constant.

[0026] The nut member may include a rod member in which the second screw portion is formed, and a head formed to extend radially from the rod member and provided with an anti-rotation part corresponding to an anti-rotation surface of the piston. Beneficial effects

[0027] A brake operating device according to an embodiment of the present disclosure can detect a rotational speed or torque of a spindle member during braking without a separate sensor.

[0028] The brake operating device according to an embodiment of the present disclosure can perform precise control without affecting the assembly and productivity of the product by changing only a part of the structure of the spindle member or a nut member.

[0029] The brake operating device according to an embodiment of the present disclosure can improve efficiency by adjusting the supply current depending on the temperature state of a power generating part or a motor. Description of drawings Fig. 1 is a schematic cross-sectional view of an electronic caliper brake according to a first embodiment of the present disclosure. Fig. 2 is a cross-sectional view of a spindle member according to the first embodiment of the present disclosure. Fig. 3 is an enlarged cross-sectional view of part A in Fig. 2. Fig. 4 is an enlarged cross-sectional view of part B in Fig. 2. Fig. 5 is a cross-sectional view of a nut member according to a second embodiment of the present disclosure. Fig. 6 is an enlarged cross-sectional view of part A in Fig. 5. Fig. Figure 7 is an enlarged cross-sectional view of part B in Fig. 5. Fig. 8 is a diagram showing a current change during a braking operation of brake operating devices according to the first and second embodiments of the present disclosure. Fig. 9 is a schematic cross-sectional view of a spindle member according to a third embodiment of the present disclosure. Fig. 10 is an enlarged cross-sectional view of part A in Fig. 9. Fig. 11 is a cross-sectional view of a nut member according to a fourth embodiment of the present disclosure. Fig. 12 is a diagram showing a current change during a braking operation of brake operating devices according to the third and fourth embodiments of the present disclosure. Type of revelation

[0030] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The following illustration is intended to fully convey the spirit of the present disclosure to a person having ordinary skill in the art to which the present disclosure pertains. The present disclosure is not limited to the embodiment shown herein, but may be embodied in other forms. The drawings are not intended to limit the scope of the present disclosure in any way, and components may be exaggerated for clarity of illustration. Throughout the application, like reference numerals refer to like elements.

[0031] Fig. 1 is a schematic cross-sectional view of an electronic caliper brake according to a first embodiment of the present disclosure, Fig. 2 is a cross-sectional view of a spindle element according to the first embodiment of the present disclosure, Fig. 3 is an enlarged cross-sectional view of part A in Fig. 2, and Fig. 4 is an enlarged cross-sectional view of part B in Fig. 2.

[0032] Referring to the Fig. 1 to 4, an electronic caliper brake 1 according to an embodiment of the present disclosure includes a carrier 10 on which a pair of pad plates 11 and 12 are installed so as to be movable forward and backward to press a disk D that rotates together with a wheel of a vehicle, a caliper housing 20 in which the carrier 10 is slidably installed and a cylinder 21 is provided, a hydraulic chamber 23 provided in the cylinder 21 and into which brake oil is introduced to generate hydraulic pressure, a piston 30 installed so as to be movable forward and backward by the hydraulic pressure generated in the hydraulic chamber 23, and an actuator 100 provided to receive an electrical signal and transmit a rotational force to the piston 30 to press or release the piston 30 toward the pad plate 11.

[0033] The pair of pad plates 11 and 12 includes the inner pad plate 11 in contact with the piston 30 and the outer pad plate 12 in contact with a finger portion 222 of the caliper housing 20, which will be described later. The two pad plates 11 and 12 are installed on the carrier 10 attached to a vehicle body and move forward and backward toward the opposite side surfaces of the disc D. A friction pad 13 is attached to a surface of each of the pad plates 11 and 12 facing the disc D.

[0034] The caliper housing 20 is slidably mounted on the carrier 10. More specifically, the caliper housing 20 includes the cylinder 21, in which the actuator 100 is installed at its rear end and the piston 30 is installed to move forward and backward therein, and the finger part 22, which is bent downward to actuate the outer brake pad plate 12 in front of it.

[0035] The piston 30 is cylindrically shaped, open on one side and hollow inside and slidably inserted into the cylinder 21.

[0036] The piston 30 is configured such that an anti-rotation surface (not shown) having a shape corresponding to an anti-rotation part 132a of a nut member 130 is formed on an inner peripheral surface thereof to limit the rotation of the nut member 130.

[0037] The piston 30 receives the rotational force of the actuator 100 to push the inner pad plate 11 toward the disc D. At this time, the piston 30 moves forward toward the inner pad plate 11 to push the inner pad plate 11, and due to the rotational force, the caliper housing 20 operates in the direction opposite to the piston 30, so that the finger part 22 pushes the outer pad plate 12 toward the disc D, thereby performing braking.

[0038] The actuating device 100 includes a force generating part 110 provided to generate a rotational force by an electrical signal, a spindle element 120 provided to rotate by receiving energy from the force generating part 110, and the nut element 130 provided to convert a rotational force of the spindle element 120 into a linear movement to press or release the piston 30 onto the inner lining plate 11 side.

[0039] The power generating part 110 may include a motor 111 for generating power by an electrical signal, a reduction gear part 112 for amplifying a torque while reducing the power of the motor 111, and a drive shaft 113 for transmitting the power of the reduction gear part 112.

[0040] One side of the spindle member 120 is connected to the drive shaft 113 to receive the rotational force of the force generating part 110, and the other side is screwed to the nut member 130 to convert the rotational force into a linear motion.

[0041] Specifically, on one side of the spindle member 120, a connecting part 123 is provided which is connected to the drive shaft 113 to receive power, on the other side of the spindle member 120, a rotating shaft 121 is provided which has a first screw portion 121a formed on its outer peripheral surface to be screwed to the nut member 130, and between the rotating shaft 121 and the connecting part 123, a flange part 122 is provided which extends in a radial direction to limit a moving range of the nut member 130.

[0042] The first screw portion 121a formed on the outer peripheral surface of the rotary shaft 121 is engaged with a second screw portion 131a to move the nut member 130 forward and backward by the rotation of the spindle member 120.

[0043] The first screw portion 121a is in the shape of an externally threaded screw protruding from the outer peripheral surface of the rotary shaft 121. It includes threads shaped to protrude helically along the rotary shaft, as well as grooves shaped to be relatively recessed between adjacent threads. In this case, the distance between adjacent threads is referred to as the pitch.

[0044] The size of the pitch between the adjacent threads of the first screw portion 121a can be changed in a constant cycle along a rotational direction.

[0045] For example, the pitch size of the first screw portion 121a may increase and then decrease with each rotation of the spindle member 120. In this case, the first screw portion 121a may have a first pitch between the threads on one side in the radial direction with respect to a center axis of the rotary shaft and a second pitch between the threads on the other side in the radial direction. A size (X+α) of the second pitch is larger than a size (X) of the first pitch, and the first pitch is formed on the opposite side of the second pitch with respect to the center axis. In this case, a variable range α of the pitch size can be determined within a range in which the spindle member 120 is rotatable within the nut member 130.

[0046] However, an increase / decrease cycle of the pitch size of the first screw portion 121a may be changed in various ways, and in a case where the pitch size is changed to be repeated in a constant cycle, the cycle may be changed to half a turn, two turns, etc., and should be understood as the same.

[0047] The nut member 130 is screwed to the spindle member 120 to convert the rotational force of the spindle member 120 into a linear movement to push or release the piston 30 toward the inner lining plate 11.

[0048] Specifically, the nut member 130 includes a rod member 131 in which the second screw portion 131a is formed to engage with the first screw portion 121a, and a head 132 formed to extend radially from one end of the rod member 131. The head 132 is provided with an anti-rotation portion 132a formed on an outer peripheral surface and having a shape corresponding to the anti-rotation surface (not shown) of the piston 30 to limit the rotation of the nut member 130.

[0049] The second screw portion 131a has the shape of an internally threaded screw having screw threads on an inner peripheral surface and includes threads shaped to protrude helically along the inner peripheral surface and grooves shaped to be relatively recessed between the adjacent threads.

[0050] The size of the pitch between the adjacent threads of the second screw portion 131a is formed to be constant.

[0051] Since the pitch of the second screw portion 131a is constant, while the pitch of the first screw portion 121a is cyclically changed, a load applied to the force generating part 110 connected to the spindle member 120 during rotation of the spindle member 120 can be cyclically changed. A detail of this will be explained later along with a diagram of Fig. 8 described.

[0052] A brake operating device 200 according to a second embodiment will be described below. In the second embodiment, the same content as in the first embodiment of the present disclosure is omitted.

[0053] Fig. 5 is a cross-sectional view of a nut member 230 according to the second embodiment of the present disclosure, Fig. 6 is an enlarged cross-sectional view of part A in Fig. 5, and Fig. Figure 7 is an enlarged cross-sectional view of part B in Fig. 5.

[0054] Referring to the Fig. 1 and 5 to 7, the actuating device 200 comprises a force generating part 210 provided to generate a rotational force by an electrical signal, a spindle element 220 provided to rotate by receiving a force from the force generating part 210, and the nut element 230 provided to convert a rotational force of the spindle element 220 into a linear movement to press or release the piston 30 onto the inner lining plate 11 side.

[0055] A rotary shaft 221 of the spindle member 220 has a first screw portion 221a formed on its outer peripheral surface, and the first screw portion 221a is engaged with a second screw portion 231a so that the nut member 230 can be moved forward and backward by the rotation of the spindle member 220.

[0056] In this case, the size of the pitch between adjacent threads of the first screw portion 221a can be made constant.

[0057] The nut member 230 includes a rod member 231 in which the second screw portion 231a is formed to be engaged with the first screw portion 221a, and a head 232 formed to extend radially from one end of the rod 231. The head 232 is provided with an anti-rotation portion 232a formed on an outer peripheral surface and having a shape corresponding to the anti-rotation portion (not shown) of the piston 30 to limit the rotation of the nut member 230.

[0058] The second screw portion 231a has the shape of an internally threaded screw having screw threads on an inner peripheral surface and includes threads shaped to protrude helically along the inner peripheral surface and grooves shaped to be relatively recessed between the adjacent threads.

[0059] In this case, the size of the pitch between the adjacent threads of the second screw portion 231a can be changed in a constant cycle along the direction of rotation.

[0060] For example, the pitch of the second screw portion 231a may increase and then decrease with each rotation of the spindle member 120. In this case, the second screw portion 231a may have a first pitch between the threads on one side in the radial direction with respect to a center axis of the rotary shaft and a second pitch between the threads on the other side in the radial direction. The size (X+α) of the second pitch is larger than the size (X) of the first pitch, and the first pitch is formed on the opposite side of the second pitch with respect to the center axis. In this case, the variable range α of the pitch size can be determined within a range in which the spindle member 220 is rotatable within the nut member 230.

[0061] However, an increase / decrease cycle of the pitch size of the second screw portion 231a may be changed in various ways, and in a case where the pitch size is changed to be repeated in a constant cycle, the cycle may be changed to half a turn, two turns, etc., and should be understood as the same.

[0062] Since the pitch of the first screw portion 221a is constant, while the pitch of the second screw portion 231a is cyclically changed, a load applied to the force generating part 210 can be cyclically changed upon rotation of the spindle member 220. A detail of this will be explained later together with the diagram of Fig. 8 described.

[0063] Next, the operation of the brake operating devices according to the first and second embodiments of the present disclosure and a change in the current of the power generating part according to its operation will be described.

[0064] Fig. 8 is a diagram showing a current change during a braking operation of the brake operating devices 100 and 200 according to the first and second embodiments of the present disclosure.

[0065] With reference to the Fig. 1 and Fig. 8, the electronic caliper brake 1 with the brake operating device 100 according to the first embodiment of the present disclosure generates a rotational force by transmitting an electrical signal to the force generating part 110 of the operating device 100 during the braking operation. As the spindle member 120, which receives the rotational force, rotates, the nut member 130 moves forward to push the piston 30. Accordingly, the piston 30 presses the pad plates 11 and 12 against the disc D to perform the braking operation.

[0066] At this time, a change in the current applied to the actuator 100 is detected with reference to the Fig. The diagram shown in Figure 8 describes this.

[0067] Depending on the chronological sequence, it can be divided into a first to third section.

[0068] The first section is a section in which an initial load is generated to generate steady-state power for the actuator 100. The second section is a section in which the spindle member 120 rotates and the nut member 130 advances, but a relatively small load is generated until just before friction occurs between the pad plates 11 and 12 and the disk D. The third section is a section in which friction occurs between the pad plates 11 and 12 and the disk D, so that the nut member 130 can no longer advance, and a large steady-state load is applied to the actuator 100.

[0069] Specifically, the first section is a section in which the power generating part 110 is operated and an instantaneous high current is required to operate the spindle element 120 in a stationary state.

[0070] The third stage is a stage where the braking operation is completed because the lining plates 11 and 12 can no longer move forward by coming into close contact with the disc D. That is, the spindle element 120 can no longer rotate, and the stationary load is generated, so the current supplied to the power generating part 110 increases sharply. At this time, when the supplied current reaches a high current (target current) above a certain value, the current supply is stopped and the braking operation is completed.

[0071] The second section is the section before friction occurs between the lining plates and the disc through the piston 30, while the spindle element 120 rotates and the nut element 130 moves forward. The second section requires a low current because the load is relatively light compared to the first section.

[0072] At this time, in the general actuator 100, the load applied to the actuator 100 in the second section is constant, so the supply current is kept constant. Therefore, it is impossible to accurately calculate the actual speed and torque of the spindle element 220 in the second section without a separate sensor.

[0073] On the other hand, in the actuator 100 according to the first embodiment of the present disclosure, since the lead size of the first screw portion 121a changes cyclically when the screw member 120 and the nut member 130 are engaged, the load applied to the actuator 100 changes in a constant cycle. That is, the current in the actuator 100 changes cyclically in the second section. Accordingly, it is possible to calculate the actual rotational speed (rpm) and torque of the screw member 120 until the braking operation is started and stopped in the second section.

[0074] Furthermore, depending on the operating time and intensity, the force-generating part 110 of the actuator 100 may overheat, causing the temperature condition to change. The resistance value of the force-generating part 110 changes depending on the temperature, so the rotational speed of the spindle element 120 may vary. In this case, the actuator 100 of the present disclosure may detect the rotational speed of the spindle element 120, allowing the temperature of the force-generating part 110 to be inversely calculated from the rotational speed data as a function of temperature. Thus, the input current or torque required for the temperature condition can be precisely and efficiently controlled.

[0075] The above description of the diagram of Fig. 8 can also be applied to the second embodiment. Specifically, the actuator 200 according to the second embodiment is provided such that the lead size of the first screw portion 221a of the screw member 220 is constant, and the lead size of the second screw portion 231a of the nut member 230 is cyclically changed. That is, the lead structure formed in the screw member 220 and the nut member 230 according to the second embodiment is opposite to the lead structure formed in the screw member 120 and the nut member 230 according to the first embodiment. Accordingly, it can be understood that the principle of generating a load in the second portion is the same as in the first embodiment.

[0076] Next, a brake operating device 300 according to the third embodiment will be described. The same content as in the first embodiment of the present disclosure will be omitted.

[0077] Fig. 9 is a schematic cross-sectional view of a spindle element 300 according to a third embodiment of the present disclosure, and Fig. 10 is an enlarged cross-sectional view of part A in Fig. 9.

[0078] Referring to the Fig. 1, Fig. 9 and Fig. 10, the actuating device 300 comprises a force generating part 310 provided to generate a rotational force by an electrical signal, a spindle element 320 provided to rotate by receiving energy from the force generating part 310, and a nut element 330 provided to convert a rotational force of the spindle element 320 into a linear movement to press or release the piston 30 onto the inner lining plate 11 side.

[0079] A rotary shaft 321 of the spindle member 320 has a first screw portion 321a formed on its outer peripheral surface, and the first screw portion 321a is engaged with a second screw portion 331a so that the nut member 330 can be moved forward and backward by the rotation of the spindle member 320.

[0080] The first screw portion 321a has the shape of an externally threaded screw formed on the outer peripheral surface of the rotary shaft, and includes threads shaped to protrude helically along the rotary shaft and grooves shaped to be relatively recessed between the adjacent threads.

[0081] The size of the pitch between the adjacent threads of the first screw portion 321a may be constant.

[0082] On the grooves of the first screw portion 321a, a plurality of projections 321b may be formed in a constant cycle along a rotation direction.

[0083] For example, the projection 321b may be shaped to protrude in a cycle of one revolution along the rotation direction.

[0084] When the spindle member 320 and the nut member 330 are engaged and rotated, the projection 321b can generate a load by cyclically gripping the nut member 330. For example, the projection 321b can engage an inner peripheral surface of one end of a rod member 331 or a projection (not shown) provided in the groove of the second screw portion 331a of the nut member 330.

[0085] However, the position where the protrusion 321b is formed is not limited to this, and as long as the protrusion 321b can generate a cyclic load when the spindle member 320 rotates, the protrusion 321b may be provided at various positions such as the thread pitch, and it should be understood in the same manner as above.

[0086] The nut member 330 is screwed to the spindle member 320 to convert the rotational force of the spindle member 320 into a linear movement to push or release the piston 30 toward the inner lining plate 11.

[0087] Specifically, the nut member 330 includes the rod member 331 in which the second screw portion 331a is formed to be engaged with the first screw portion 321a, and a head 332 formed to extend radially from one end of the rod member 331. The head 332 is provided with an anti-rotation portion 332a formed on an outer peripheral surface and having a shape corresponding to the anti-rotation portion (not shown) of the piston 30 to limit the rotation of the nut member 330.

[0088] The second screw portion 331a is in the shape of an internally threaded screw having threads on an inner peripheral surface. The second screw portion 331a includes threads shaped to protrude helically along the inner peripheral surface and grooves shaped to be relatively recessed between adjacent threads.

[0089] A size of a pitch between the adjacent threads of the second screw portion 331a may be formed constant.

[0090] At least one projection (not shown) corresponding to the above-described projection of the first screw portion 321a may be formed on the groove of the second screw portion 331a.

[0091] Therefore, the projection 321b of the first screw portion 321a of the spindle member 320 can be caught on a projection (not shown) provided on the inner peripheral surface of the end of the rod member 331 or the groove of the second screw portion 331a in a constant cycle. Accordingly, the load applied to the force generating part 310 during the rotation of the spindle member 320 can be cyclically changed. A detail of this will be explained later along with a diagram of Fig. 12 described.

[0092] A brake operating device 400 according to a fourth embodiment will be described below. The same content as in the third embodiment of the present disclosure will be omitted.

[0093] Fig. 11 is a cross-sectional view of a nut member according to the fourth embodiment of the present disclosure.

[0094] Referring to the Fig. 1 and Fig. 11, the actuating device 400 comprises a force generating part 410 provided to generate a rotational force by an electrical signal, a spindle element 420 provided to rotate by receiving a force from the force generating part 410, and a nut element 430 provided to convert a rotational force of the spindle element 420 into a linear movement to press or release the piston 30 onto the inner lining plate 11 side.

[0095] A rotary shaft 421 of the spindle member 420 has a first screw portion 421a formed on its outer peripheral surface, and the first screw portion 421a is engaged with a second screw portion 431a so that the nut member 430 can be moved forward and backward by the rotation of the spindle member 420.

[0096] The first screw portion 421a has the shape of an externally threaded screw formed on the outer peripheral surface of the rotary shaft 421. The first screw portion 421a includes threads shaped to protrude helically along the rotary shaft 421 and grooves shaped to be relatively recessed between the adjacent threads.

[0097] At least one projection (not shown) corresponding to a projection of the second screw portion 431a, which will be described later, may be formed on the groove of the first screw portion 421a.

[0098] The nut member 430 includes the rod member 431, in which the second screw portion 431a is formed to be engaged with the first screw portion 421a of the spindle member 420, and a head 432 formed to extend radially from one end of the rod member 431. The head 432 is provided with an anti-rotation portion 432a formed on an outer peripheral surface and having a shape corresponding to the anti-rotation portion (not shown) of the piston 30 to limit the rotation of the nut member 430.

[0099] The second screw portion 431a is in the shape of an internally threaded screw having threads on an inner peripheral surface. The second screw portion 431a includes threads shaped to protrude helically along the inner peripheral surface and grooves shaped to be relatively recessed between adjacent threads.

[0100] A size of a pitch between the adjacent threads of the second screw portion 431a may be formed constant.

[0101] In this case, a plurality of protrusions 431b may be formed on the grooves between the threads of the second screw portion 431a in a constant cycle along a rotational direction.

[0102] For example, the protrusion 431b may be shaped to protrude in a cycle of one revolution along the rotation direction.

[0103] When the spindle member 420 and the nut member 430 are engaged and rotated, the projection 431b can generate a load by cyclically holding the spindle member 420. For example, the projection 431b can be gripped at one end of the rotating shaft 421 or can engage the projection (not shown) provided on the groove of the first screw portion 421a.

[0104] However, the position where the protrusion 431b is formed is not limited thereto, and as long as the protrusion 431b can generate a cyclic load when the spindle member 420 rotates, the protrusion 431b may be provided at various positions such as the thread of the second screw portion 431a, and it should be understood in the same manner as above.

[0105] Therefore, the projection 431b of the second screw portion 431a of the nut member 430 can be caught on a projection (not shown) provided at the end of the rotary shaft 421 or in the groove of the first screw portion 421a in a constant cycle. Accordingly, the load applied to the force generating part 410 during the rotation of the spindle member 420 can be cyclically changed. A detail of this will be explained later along with the diagram in Fig. 12 described.

[0106] The following describes the operation of the brake operating devices according to the third and fourth embodiments of the present disclosure and a change in the current of the power generating part depending on the operation. A description of the content related to the Fig. 8, is omitted.

[0107] Fig. 12 is a diagram showing a current change during a braking operation of the brake operating devices 300 and 400 according to the third and fourth embodiments of the present disclosure.

[0108] With reference to the Fig. 1 and Fig. 12, in the electronic caliper brake 1 with the brake operating device 100 according to the third embodiment of the present disclosure, since the operation in the first section and in the third section during the braking operation is identical to the description of the operation in Fig. 8, a description of it is omitted, and a functioning of the second section in the diagram of Fig. 12 is described.

[0109] The second section is the section before friction occurs between the lining plates and the disc by the piston 30, while the spindle element 420 rotates and the nut element 430 advances. The second section requires a low current because the load is relatively light compared to the first section.

[0110] At this time, in the general actuator 100, the load applied to the actuator 100 in the second section is constant, so the current is kept constant. Therefore, it is impossible to accurately calculate the actual speed and torque of the spindle element 420 in the second section without a separate sensor.

[0111] On the other hand, in the actuator 300 according to the third embodiment of the present disclosure, a protrusion 321b is formed on the groove of the first screw portion 321a in a constant cycle. When the screw member 320 and the nut member 330 mesh, the load acting on the actuator 300 is changed in a constant cycle. That is, the current in the actuator 300 is changed in a constant cycle in the second section. Accordingly, it is possible to calculate the actual rotational speed (rpm) and torque of the screw member 320 before the braking operation is initiated and then terminated in the second section.

[0112] Furthermore, depending on the operating time and intensity, the force-generating part 310 of the actuator 300 may overheat, causing the temperature condition to change. The resistance value of the force-generating part 310 changes depending on the temperature, so the rotational speed of the spindle element 320 may vary. In this case, the actuator 300 of the present disclosure can detect the rotational speed of the spindle element 320, so that the temperature of the force-generating part 310 can be inversely calculated from the rotational speed data as a function of temperature. Thus, the input current or torque required for the temperature condition can be precisely and efficiently controlled.

[0113] The description of the diagram in Fig.11 can also be applied to the fourth embodiment. Specifically, in the actuator 400 of the fourth embodiment, the protrusion 431b is formed in a constant cycle in the groove of the second screw portion 431a of the nut member 430, and the principle of generating a load in the second portion is the same, and therefore, it should be understood in the same way as the third embodiment described above.

[0114] The foregoing has illustrated and described specific embodiments, but it should be understood by those skilled in the art that the disclosure is not limited to the embodiments described above and various changes and modifications may be made without departing from the following claims.

Claims

[1] A brake actuating device (100) configured to push or release a piston (30) toward a brake pad and controlled by an electrical signal, the brake actuating device comprising: a force generating part (110) provided for generating a force by an electrical signal; a spindle member (120) adapted to rotate by receiving a force from the force generating member (110) and having a first screw portion (121a) formed on an outer peripheral surface; and a nut member (130) provided for pressing or releasing the piston (30), the nut member (130) having a second screw portion (131a) formed on an inner peripheral surface to engage with the first screw portion (121a), wherein the size of the pitch of the second screw portion (131a) is constant, characterized by in that a size of a pitch between adjacent threads of the first screw portion (121a) changes in a constant cycle along a direction of rotation, wherein the size of the pitch of the first screw portion (121a) changes cyclically, so that a load exerted on the force generating part (110) connected to the spindle element (120) during rotation of the spindle element (120) changes cyclically. [2] Brake operating device (100) according to claim 1, wherein the first screw portion (121a) has a first pitch between the threads provided on one side and a second pitch between the threads provided on the other side, and a value (X+α) of the second gradient is greater than a value (X) of the first gradient. [3] The brake operating device (100) according to claim 2, wherein the first slope is formed on the opposite side of the second slope with respect to a central axis of the spindle member (120). [4] A brake actuating device (200) configured to push or release a piston (30) toward a brake pad and controlled by an electrical signal, the brake actuating device comprising: a force generating part (210) provided for generating a force by an electrical signal; a spindle member (220) adapted to rotate by receiving a force from the force generating member (210) and having a first screw portion (221a) formed on an outer peripheral surface; and a nut member (230) provided for pressing or releasing the piston (30), the nut member (230) having a second screw portion (231a) formed on an inner peripheral surface to engage with the first screw portion (221a), wherein the size of the pitch of the first screw portion (221a) is constant, characterized by in that a size of a pitch between adjacent threads of the second screw portion (231a) changes in a constant cycle along a direction of rotation, wherein the size of the pitch of the second screw portion (231a) changes cyclically, so that a load exerted on the force generating part (210) connected to the spindle element (220) during rotation of the spindle element (220) changes cyclically. [5] Brake actuating device (200) according to claim 4, wherein the second screw portion (231a) has a first pitch between the threads provided on one side and a second pitch between the threads provided on the other side, and a value (X+α) of the second gradient is greater than a value (X) of the first gradient. [6] The brake operating device (200) according to claim 4, wherein the first slope is formed on the opposite side of the second slope with respect to a central axis of the nut member (230). [7] A brake actuating device (300) configured to push or release a piston (30) toward a brake pad and controlled by an electrical signal, the brake actuating device (300) comprising: a force generating part (310) provided for generating a force by an electrical signal; a spindle member (320) adapted to rotate by receiving a force from the force generating member (310) and having a first screw portion (321a) formed on an outer peripheral surface; and a nut member (330) provided for pressing or releasing the piston (30), the nut member (330) having a second screw portion (331a) formed on an inner peripheral surface to engage with the first screw portion, characterized by that the first screw portion (321a) has a plurality of projections (321b) shaped to protrude in a constant cycle along a direction of rotation into grooves between threads, wherein when the spindle member (320) and the nut member (330) are engaged and rotated, the projection (321b) generates a load by being cyclically held to the nut member (330). [8] The brake operating device (300) according to claim 7, wherein the projections are shaped to protrude in a cycle of one revolution along the rotational direction. [9] Brake operating device (300) according to claim 7, wherein the size of the pitch between the adjacent threads of the second screw portion (331a) is constant. [10] A brake actuating device (400) configured to push or release a piston (30) toward a brake pad and controlled by an electrical signal, the brake actuating device (400) comprising: a force generating part (410) provided for generating a force by an electrical signal; a spindle member (420) adapted to rotate by receiving a force from the force generating member (410) and having a first screw portion (421a) formed on an outer peripheral surface; and a nut member (430) provided for pressing or releasing the piston (30), the nut member (430) having a second screw portion (431a) formed on an inner peripheral surface to engage with the first screw portion (421a), characterized by in that the second screw portion (431a) has a plurality of projections (431b) shaped to protrude in a constant cycle along a rotational direction into grooves between threads, wherein when the spindle member (420) and the nut member (430) are engaged and rotated, the projection (431b) generates a load by being cyclically held on the spindle member (420). [11] The brake operating device (400) according to claim 10, wherein the projections (431b) are shaped to protrude in a cycle of one revolution along the rotational direction. [12] Brake operating device (400) according to claim 10, wherein the size of the pitch between the adjacent threads of the first screw portion (421a) is constant. [13] Brake operating device (100, 200, 300, 400) according to claim 1, 4, 7 or 10, wherein the nut member (130, 230, 330, 430) comprises a rod member (131, 231, 331, 431, 431) in which the second screw portion (131a, 231a, 331a, 431a) is formed, and a head (132, 232, 332, 432) formed to extend radially from the rod member (431) and provided with an anti-rotation part (132a, 232a, 332a, 432a) corresponding to an anti-rotation surface of the piston (30).

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