Electromechanical Brake Booster Device

Abstract

To provide an electromechanical brake booster configured to make a sensor detect displacement of a member which moves together with a brake pedal so as to drive a motor, and eliminate the necessity for positioning in a circumferential direction of the sensor, while avoiding a restriction in design on the sensor and the device from being enlarged in size.SOLUTION: An electromechanical brake booster comprises an input rod 20 connected to a brake pedal BP, a control rod 40 which has a cylindrical body 220 to be detected attached to an outer peripheral surface thereof and which linearly moves in an axial direction accompanying operation of the brake pedal BP in tandem with the input rod 20, and a position sensor 52 that detects displacement of the control rod 40, where the position sensor 52 is arranged outside the body 220 to be detected. The position sensor 52 detects displacement of the body 220 to be detected so as to detect displacement of the control rod 40.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to an electromechanical brake booster for amplifying the force applied when the brake pedal is depressed in an automobile. [Background technology]

[0002] Brake boosters that amplify the force applied when the brake pedal is depressed have been known for some time to assist in braking operations in automobiles. For example, a vacuum brake booster that utilizes the negative pressure of the engine, such as the invention described in JP 54-90459 A (Patent Document 1), has been commonly used.

[0003] In recent years, the movement towards carbon neutrality has been gaining momentum in countries around the world, and in order to achieve the goal of moving away from fossil fuels, the transition to vehicles that do not have engines as their power source, such as electric vehicles and fuel cell vehicles, has become an important issue for the future of the automotive industry.

[0004] In that case, one of the differences between conventional engine-equipped vehicles and non-engine vehicles such as electric vehicles is that, since they do not have an engine, the engine negative pressure (intake pipe negative pressure) used in conventional systems is not generated, which creates the problem that various parts that use negative pressure cannot be used.

[0005] Therefore, there is a need for a brake booster that can provide a high braking force that can be used in automatic braking as an alternative to a vacuum brake booster. For example, electromechanical brake boosters equipped with a motor as a power source are known, such as the inventions described in JP 2018-199448 A (Patent Document 2) and JP 2018 / 097278 A (Patent Document 3).

[0006] These conventional electromechanical brake boosters make it possible to amplify the force applied when stepping on the brake pedal by using an electrically powered motor, even in vehicles that do not have an engine.

[0007] Here, by detecting the displacement of an input rod (input member) connected to the brake pedal and a control rod (assist member) that works in conjunction with the input rod, it is possible to control the motor to be driven when the brake pedal is depressed. For example, an invention described in JP 2007-191133 A (Patent Document 4) is known that uses a linear potentiometer with a sensor rod attached to a bracket extending from the input rod as a displacement detection means.

[0008] As a displacement detection means utilizing a magnetic position sensor in a conventional electromechanical brake booster, for example, as shown in FIG. 9, a method is generally known in which a detectable body 26, which is a magnet, is attached to one end of an arm 25 that extends in both directions perpendicular to the axis centered on an input rod 20, and a pair of regulating plates 27, 27 for regulating the rotation are erected near the other end of the arm 25, so that the detectable body 26 moves only in the axial direction, and the displacement of the detectable body 26 is detected by a position sensor 52 arranged outside the detectable body 26, thereby detecting the displacement of the input rod 20 which moves in conjunction with the detectable body 26.

[0009] When arranging the sensor rod and the object to be detected 26 away from the input rod 20 in this manner, it is necessary to prevent interference with the spring that maintains the input rod 20 in an upright position, which creates problems such as design limitations and an increase in the size of the device itself.

[0010] Therefore, for example, it is known to position a stroke sensor near the end face of the opening of the base and provide a detection part on the input member that is detected by the stroke sensor, as in the invention described in JP 2017-114395 A (Patent Document 5).The invention described in Patent Document 5 is said to reduce the possibility of interference with parts outside the base and improve the layout flexibility of the stroke sensor.

[0011] However, the structures of Patent Document 4, Patent Document 5, and the conventional invention shown in Fig. 9 all require circumferential positioning. That is, there is an inconvenience in that the sensor must be positioned in the correct direction for normal operation both at the time of design and at the time of manufacture. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] Japanese Patent Application Publication No. 54-90459 [Patent Document 2] JP 2018-199448 A [Patent Document 3] Re-tabled publication 2018 / 097278 [Patent Document 4] JP 2007-191133 A [Patent Document 5] JP 2017-114395 A Summary of the Invention [Problem to be solved by the invention]

[0013] The present invention aims to eliminate the need for circumferential positioning of the sensor while avoiding design restrictions related to the sensor and the increase in size of the device itself in an electromechanical brake booster that drives a motor by using a sensor to detect the displacement of a member that is linked to the brake pedal. [Means for solving the problem]

[0014] The electromechanical brake booster achieved to solve the above problems is as follows: An input rod connected to the brake pedal; a control rod having a cylindrical detection object attached to its outer circumferential surface and moving linearly in the axial direction in conjunction with the input rod in response to operation of the brake pedal; a position sensor for detecting a displacement of the control rod; the position sensor is disposed outside the detection object, and the displacement of the detection object is detected by the position sensor, thereby detecting the displacement of the control rod. It is characterized by:

[0015] According to the present invention, a cylindrical detectable object is attached to the outer circumferential surface of a control rod, and a position sensor that detects the displacement of the detectable object is positioned outside the detectable object. This makes it possible to avoid design restrictions related to the sensor and the increase in size of the device itself, while eliminating the need for circumferential positioning of the sensor.

[0016] Also, a ball stud is attached to one end of the control rod; The ball stud has a shaft portion, a spherical head portion, and a flange portion formed to protrude between the shaft portion and the head portion, When the cylindrical detectable object is attached so that it cannot fall off by inserting the shank of the ball stud into a through hole formed in line with its axis and holding it between the flange portion of the ball stud and the end of the control rod, the detectable object can be attached reliably and easily.

[0017] Furthermore, a biasing member is disposed inside the input rod for biasing the input rod and the control rod in directions separating them from each other to maintain the input rod in a constant position, When the input rod and the control rod are connected by crimping, there is no need to place a spring on the outer periphery of the input rod, so it is possible to utilize the space around the input rod to place a position sensor.

[0018] In addition, it is equipped with an ON-OFF sensor that is attached to the brake pedal and sends an ON signal when the brake pedal is pressed and an OFF signal when the brake pedal is not pressed. When the position of the detectable object when the ON-OFF sensor sends an OFF signal after the engine is started is corrected as the initial position, even if there is variation in the degree of detection of the detectable object in the circumferential direction, the correction can be performed to ignore the variation and use the object without problems.

[0019] The electromechanical brake booster according to the present invention is An input rod connected to the brake pedal; a control rod which moves linearly in an axial direction in response to operation of the brake pedal in cooperation with the input rod; a sensor unit including a position sensor that detects a displacement of the control rod; a motor section that operates in response to the displacement of the control rod; a control unit that drives the motor unit by using information obtained from the sensor unit; a rotary-to-linear motion conversion unit arranged on an outer periphery of the control rod, the rotary-to-linear motion conversion unit including a shaft member and a rotating member, and interlocking with the motor unit to convert the rotary motion of the rotating member into linear motion of the shaft member; a bracket that restricts the axial rotation of the shaft member and moves in an axial direction in conjunction with the shaft member; A return spring for biasing the bracket to return to its original position after it has been moved; It is desirable to further include a master cylinder connected to the tip end side of the control rod and the shaft member, and operated by linear motion of the control rod or the shaft member.

[0020] In addition, it is particularly desirable that the input rod, the control rod, the motor section, the rotary-linear conversion section, the bracket, and the master cylinder are all arranged coaxially, as this allows for a compact overall configuration. Effect of the Invention

[0021] According to the present invention, it is possible to avoid design restrictions on the position detection sensor and an increase in size of the device itself, while eliminating the need for circumferential positioning of the sensor. [Brief description of the drawings]

[0022] [Figure 1] 1 is a perspective view showing a preferred embodiment of an electromechanical brake booster according to the present invention; [Diagram 2] FIG. 2 is a top view of the embodiment shown in FIG. [Diagram 3] FIG. 2 is a plan view of the embodiment shown in FIG. 1 with the cover removed. [Figure 4] Cross-sectional view taken along line AA in FIG. [Diagram 5] Cross-sectional view of line BB shown in Figure 2. [Figure 6] FIG. 2 is a cross-sectional view of a main portion of the embodiment shown in FIG. [Figure 7] 2 is an exploded perspective view showing an input rod, a biasing member, and a control rod in the embodiment shown in FIG. 1. [Figure 8] 2A and 2B are schematic diagrams showing the embodiment shown in FIG. 1, where FIG. 2A is a plan view and FIG. [Figure 9] 1A and 1B are schematic diagrams showing a conventional example, in which (a) is a plan view and (b) is a front view. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0024] 1 to 5 show a preferred embodiment of the electromechanical brake booster of the present invention, and this electromechanical brake booster 1 has a casing 10, an input rod 20, a biasing member 30, a control rod 40, a sensor unit 50, a motor unit 60, a control unit 70, a rotary-linear motion conversion unit 80, a bracket 90, a support 100, a return spring 110, and a master cylinder 120.

[0025] The casing 10 is composed of a cylindrical cover 11 and a doughnut-shaped bottom plate 12. Reference numeral 13 denotes a window formed in the cover 11 for mounting an external connector, reference numeral 14 denotes a fixing screw for fixing the cover 11 and the bottom plate 12, and reference numeral 15 denotes a fixing member for fixing the casing 10 to the body of an automobile.

[0026] The input rod 20 is rod-shaped overall, movable in the axial direction and swingable within a certain angular range, and has a connection hole 21 extending in the axial direction of the input rod 20 and a spring retaining hole 22 extending in the axial direction and having a smaller diameter than the connection hole 21 formed continuously on its end face at one end (the control rod 40 side), and a brake pedal connector 23 is attached to the other end, which is rotatable in the circumferential direction and is used to connect to the brake pedal BP.

[0027] The biasing member 30 is made up of a coil spring 31 that exerts a repulsive force, and a retainer 32. The retainer 32 has a conical shape as a whole, and has a mortar-shaped receiving surface 33 on the inside.

[0028] The control rod 40 is rod-shaped overall and can move axially. One end (the input rod 20 side) has a ball stud 210 fixed thereto by a flange portion 213, with a cylindrical detectable object 220, which is a magnet for position detection, attached thereto so that it cannot fall off. The other end has a step portion 42 for engaging with a plate 41 and a small-diameter tip portion 44 for attaching a coil spring 43 to the outside.

[0029] The retainer 32 is positioned in the connecting hole 21 of the input rod 20 with the receiving surface 33 facing outward, and the coil spring 31 is positioned between the spring holding hole 22 and the retainer 32. The input rod 20 and the control rod 40 are crimped and connected by inserting the spherical head 212 of a ball stud 210 attached to the control rod 40 into the connection hole 21 of the input rod 20 and deforming the outer edge of the connection hole 21 to reduce its diameter with the receiving surface 33 of the retainer 32 in contact with the ball stud 210, thereby forming a ball joint mechanism.

[0030] The sensor section 50 is composed of a sensor board 51 and a position sensor 52, and the amount of displacement of the detection target 220 detected by the position sensor 52 is output as a signal via the sensor board 51.

[0031] The motor section 60 is made up of a stator 61, a rotor 62, a rotating shaft 63 that rotates in synchronization with the rotor 62, and two bearings 64, 65 that support the rotating shaft 63 rotatably in the circumferential direction. Reference numerals 66, 67 denote detection gears for detecting the number of rotations, and reference numeral 68 denotes a motor cover that is attached so as to stand from the bottom plate 12 and covers the motor section 60.

[0032] The control unit 70 is a control board 71 having the function of a motor driver for controlling the power supplied from outside via a power cable (not shown) to drive the motor unit 60. The control board 71 is connected to the position sensor 52 and the rotation speed sensor 72 via cables 73, 74, and drives the motor unit 60 using signals from each sensor.

[0033] In this embodiment, two sets of the rotation speed sensor 72 and the corresponding detection gears 66, 67 are provided, and by using rotation speed sensors with different performance, it is possible to achieve both high precision and high speed motor control, but it is also possible to provide only one set of the rotation speed sensor and the corresponding detection gears.

[0034] The rotary-linear motion conversion unit 80 is a mechanism for converting the rotary motion of the motor unit 60 into linear motion, and is configured by a feed screw mechanism including a cylindrical shaft member 81 having a thread formed on its outer periphery, a nut-shaped rotating member 82 having a thread groove formed on its inner periphery and screw-fitted with the shaft member 81, and a cylindrical connecting member 83 connecting the rotating member 82 to the rotating shaft 63. In this embodiment, the rotating member 82 and the connecting member 83 are formed separately and then integrally joined, but they may also be integrally molded.

[0035] The bracket 90 is a generally equilateral triangle in plan view, with through holes 91, 92 formed at the center and near each apex. The shaft member 81 is inserted and fixed into the through hole 91 at the center, and is attached to three posts 100 via flange bushes 93 attached to the through holes 92 near each apex, making the bracket 90 immovable in the axial direction but movable in the axial direction, restricting the axial rotation of the shaft member 81 and allowing it to move in the axial direction in unison.

[0036] Three pillars 100 are installed between the cover 11 and the bottom plate 12, and are positioned by inserting a small diameter portion 101 formed near one end into a mounting hole 16 formed in the bottom plate 12 and by bringing a large diameter portion 102 formed adjacent to the small diameter portion 101 into contact with the bottom plate 12. The pillars are fixed by attaching a nut 104 to a tip portion 103 of the pillar protruding from a mounting hole 17 formed in the cover 11.

[0037] The return springs 110 are used to urge the bracket 90 back to its original position after it has been moved, and are attached to three reinforcing pillars 100 suspended between the cover 11 and the bottom plate 12, with one end in contact with the bottom plate 12 and the other end in contact with the flange bush 93.

[0038] The master cylinder 120 comprises a cylinder bore 121 which is cylindrical with a bottom and has a first output port 122 and a second output port 123 formed on the side, a first piston 130 arranged within the cylinder bore 121, and a second piston 140 arranged within the cylinder bore 121 closer to the bottom than the first piston 130. The master cylinder 120 is arranged so that the opening of the cylinder bore 121 faces the opening at the bottom of the casing 10 and closes it, and is fixed by a bolt 125 and a nut 126 which are inserted while communicating a mounting hole 124 of the cylinder bore 121 and a mounting hole 18 of the bottom plate 12.

[0039] Both ends of the first piston 130 are formed in a cup shape, and are formed with an H-shaped cross section partitioned by a partition wall 131. An elastic body 133 which is a reaction disk is fitted into a recess 132 formed on the base end side (the control rod 40 side) of the partition wall 131, and the tip end 45 of the control rod 40 comes into contact with the elastic body 133.

[0040] Both ends of the second piston 140 are formed in a cup shape, and have an H-shaped cross section partitioned by a partition wall 141. A recess 142 is formed on the base end side (the first piston 130 side) of the partition wall 141, and a retainer rod 148 described later comes into contact with the recess 142.

[0041] In the cylinder bore 121 of the master cylinder 120, a primary chamber 127 is formed between a first piston 130 and a second piston 140, and a secondary chamber 128 is formed between the bottom of the cylinder bore 121 and the second piston 140. The inside of the cylinder bore 121 including the primary chamber 127 and the secondary chamber 128 is filled with brake fluid, which is a working fluid, and the brake fluid is supplied from a reservoir (not shown).

[0042] At this time, sealing members 151, 152 installed between the outer periphery of the first piston 130 and the inner periphery of the cylinder bore 121, and sealing members 161, 12 installed between the outer periphery of the second piston 140 and the inner periphery of the cylinder bore 121, prevent the brake fluid from leaking outside the designated compartment.

[0043] The primary chamber 127 and secondary chamber 128 of the master cylinder 120 are respectively connected to a first output port 122 and a second output port 123 formed on the side of the cylinder bore 121, and the hydraulic pressure of the brake fluid output from each output port via a separate system is supplied to the brakes (not shown) of each wheel to generate braking force.

[0044] A coil spring 134 is interposed between the first piston 130 and the second piston 140, and biases the first piston 130 and the second piston 140 in a direction separating them from each other. Inside the coil spring 134, an expandable member 135 consisting of a retainer guide 136 and a retainer rod 138 for maintaining a predetermined distance between the first piston 130 and the second piston 140 is arranged.

[0045] The retainer guide 136 is cylindrical and has a stopper portion 137 that protrudes inward at its tip. The retainer rod 138 is rod-shaped and has a flange portion 139 that protrudes radially outward at its base end. By inserting the retainer rod 138 into the retainer guide 136, the two can move relative to each other in the axial direction, and when the stopper portion 137 of the retainer guide 136 and the flange portion 139 of the retainer rod 138 interfere with each other, the expandable member 135 is expanded to a predetermined extent.

[0046] A coil spring 144 is interposed between the second piston 140 and the bottom of the cylinder bore 121, and biases the second piston 140 and the bottom of the cylinder bore 121 in a direction separating them from each other. An expandable member 145 consisting of a retainer guide 146 and a retainer rod 148 is disposed inside the coil spring 144 to maintain a predetermined distance between the second piston 140 and the bottom of the cylinder bore 121.

[0047] The retainer guide 146 is cylindrical and has a stopper portion 147 that protrudes inward at its tip. The retainer rod 148 is hollow rod-shaped and has a flange portion 149 that protrudes radially outward at its base end. By inserting the retainer rod 148 into the retainer guide 146, the two become capable of moving relative to each other in the axial direction, and when the stopper portion 147 of the retainer guide 146 and the flange portion 149 of the retainer rod 148 interfere with each other, the expandable member 145 is expanded to a predetermined extent.

[0048] In this embodiment, the input rod 20, the control rod 40, the motor section 60, the rotary-to-linear motion conversion section 80, the bracket 90 and the master cylinder 120, which are directly related to the operation of the brake booster, are all arranged coaxially (see Figures 4 and 5), making it possible to achieve a space-saving configuration overall.

[0049] The operation of the electromechanical brake booster 1 according to this embodiment will now be described.

[0050] With the electromechanical brake booster 1 installed in an automobile, when the driver depresses the brake pedal BP, the input rod 20 connected to the brake pedal BP moves axially, and the control rod 40 moves linearly in synchronization with the input rod 20.

[0051] At this time, the control rod 40 and the shaft member 81 are not synchronized and can move axially separately, so that only the control rod 40 moves without changing the position of the shaft member 81.

[0052] Then, the control rod 40 advances the first piston 130 and the second piston 140 against the biasing forces of the coil springs 43 , 134 , and 144 .

[0053] In addition, when the control rod 40 moves, the control unit 70 uses a signal sent from the position sensor 52 that detects the displacement to control the supply of power and an operating signal to the motor unit 60, causing the motor unit 60 to operate and rotate.

[0054] In addition, a separate rotation speed sensor 72 is provided which detects the motor rotation speed by detecting the rotation speed of detection gears 66, 67 attached to the rotating shaft 63. When the control unit 70 controls the supply of power and an operating signal to the motor unit 60, the signal sent from the rotation speed sensor 72 to the control unit 70 via a cable 74 can be utilized.

[0055] When the motor unit 60 rotates, the rotating member 82 rotates in synchronization with the rotating shaft 63 via the connecting member 83, but since the axial rotation of the shaft member 81 is restricted by the bracket 90, the rotational movement of the rotating member 82, which is screwed into the shaft member 81, is converted into linear movement, and the first piston 130 and second piston 140 move forward on the axis.

[0056] At this time, the bracket 90 also moves in synchronization with the shaft member 81 in a direction that advances the first piston 130 and the second piston 140 on the axis while compressing the return spring 110, but since the bracket 90 slides while being guided by the support 100 via the flange bush 93, smooth operation is possible.

[0057] Then, the shaft member 81 advances the first piston 130 and the second piston 140 against the biasing forces of the coil springs 134, 144 via the plate 42.

[0058] In this way, the force exerted when the driver depresses the brake pedal BP is applied directly to the first piston 130 and the second piston 140 of the master cylinder 120 via the input rod 20 and the control rod 40, and in addition, the pressing force obtained by converting the rotational motion of the motor section 60 into the linear motion of the shaft member 81 is applied to the first piston 130 and the second piston 140 of the master cylinder via the shaft member 81, thereby making it possible to amplify the force exerted when the driver depresses the brake pedal BP by using a motor driven by electricity.

[0059] Then, as the driver releases the brake pedal BP and the brake pedal BP returns to its original position, the input rod 20 and control rod 40 connected to the brake pedal BP also return to their original positions. As the control rod 40 moves, the control unit 70 controls the supply of power and an actuation signal to the motor unit 60 in response to a signal from the position sensor 52 which detects the displacement, and the motor unit 60 is actuated to rotate in the reverse direction.

[0060] When the motor unit 60 rotates in reverse, the rotating member 82 rotates in reverse in synchronization with the rotating shaft 63 via the connecting member 83. However, since the axial rotation of the shaft member 81 is restricted by the bracket 90, the rotational motion of the rotating member 82 which is screwed into the shaft member 81 is converted into linear motion, and the first piston 130 and the second piston 140 on the axis move backward.

[0061] Furthermore, even if the motor unit 60 is unable to reverse normally due to a malfunction of the motor unit 60 or the control unit 70, the biasing forces of the coil springs 134, 144 and the return spring 110 will cause the shaft member 81 and the first piston 130 and second piston 140 of the master cylinder to retract and return to their original positions before operation.

[0062] The main points of the present invention will be described below with reference to FIG. 6, which is a cross-sectional view of a main portion of the embodiment shown in FIG. 1, FIG. 7, which is an exploded perspective view of some components in the embodiment shown in FIG. 1, FIG. 8, which is a schematic view of the embodiment shown in FIG. 1, and FIG. 9, which is a schematic view of a conventional example.

[0063] As shown in Figures 6 and 7, in a preferred embodiment of the present invention, the retainer 32 is positioned in the connecting hole 21 of the input rod 20 with the receiving surface 33 facing outward, and the coil spring 31 is positioned between the spring holding hole 22 and the retainer 32. The input rod 20 and the control rod 40 are connected by inserting a shaft 211 into the connection hole 21 of the input rod 20 and deforming the outer edge of the connection hole 21 to reduce its diameter with the receiving surface 33 of the retainer 32 in contact with the head 212 of the ball stud 210, and crimping the connection hole 21 of the input rod 20 into the head 212 of the ball stud 210.

[0064] At this time, the biasing force of the coil spring 31 transmitted through the retainer 32 acts in a direction separating the ball stud 210 and the input rod 20 from each other, thereby exerting the same effect as a conventional spring for maintaining rod position, and preventing the input rod 20 from collapsing under its own weight and preventing a gap from occurring between the input rod 20 and the control rod 40, which could result in abnormal noise or erratic behavior.

[0065] In addition, in this embodiment, the space around the outer periphery of the input rod 20 is utilized, and the sensor base 51 and position sensor 52 of the sensor unit 50 are arranged on the upper surface of the bracket 90 in correspondence with the object to be detected 220, making it possible to detect the positions of the input rod 20 and the control rod 40 in a space-saving manner.

[0066] The shaft 211 of the ball stud 210 is inserted into a through hole 221 formed in alignment with the axis of the cylindrical detectable object 220, which is a magnet, and one end 222 of the detectable object 220 is held by a flange portion 213 formed to protrude between the shaft portion 211 and the head 212, while the other end 223 of the detectable object 220 is held by the end of the control rod 40, thereby mounting the detectable object 220 on the control rod 40 so that it cannot fall off.

[0067] In this way, by attaching the detectable body 220 integrally to the control rod 40 by the ball stud 210, there is no need to provide an arm 25 as in the conventional example shown in Figure 9, and the periphery of the input rod 20 and the control rod 40 can be used freely as shown in the schematic diagram of Figure 8, thereby avoiding design restrictions and the increase in size of the device itself.

[0068] Furthermore, since the detectable object 220 is cylindrical, there is no need to provide a regulating plate 27 as in the conventional example shown in FIG. 9, and the detectable object 220 is free to rotate in the circumferential direction as shown in the schematic diagram of FIG. 8, making it unnecessary to position the detectable object 220 in the circumferential direction relative to the position sensor 52.

[0069] Although the shape of the detection object 220 is cylindrical in this embodiment, it may be, for example, columnar without a through hole (not shown).

[0070] As shown in FIG. 6, an ON-OFF sensor 230 is attached to the brake pedal BP, which transmits an ON signal when the brake pedal is depressed and an OFF signal when the brake pedal is not depressed. The ON-OFF sensor 230 is connected to the control unit 70.

[0071] This ON-OFF sensor 230 is for correcting the position of the detection object 220 when an OFF signal is transmitted from the ON-OFF sensor 230 after the engine is started, using the position as an initial position.

[0072] That is, in this embodiment, the input rod 20 and the control rod 40 are rotatable relative to each other in the circumferential direction, and therefore the circumferential orientation is not required in advance at the time of design, manufacture, or use. However, the detectable body 220, which is a magnet, may not have a uniform magnetic field in the circumferential direction, and therefore, unless correction is performed, there is a possibility that deviations will occur when detecting displacement.

[0073] In contrast, even if there is variation in the degree of detection of the detectable object 220 in the circumferential direction, the variation can be ignored and the device can be used without problems by correcting the position of the detectable object 220 when the OFF signal is transmitted from the ON-OFF sensor 230 after the engine is started as the initial position.

[0074] The correction may be performed every time an OFF signal is sent after the engine is started, or may be performed only when an OFF signal is sent for the first time after the engine is started.

[0075] As described above, according to the present invention, it is possible to avoid design restrictions on position detection sensors and increases in size of the device itself, while eliminating the need for circumferential positioning of the sensors. [Explanation of symbols]

[0076] 1 electromechanical brake booster, 10 casing, 11 cover, 12 bottom plate, 13 window, 14 fixing screw, 15 fixing member, 16 mounting hole, 17 mounting hole, 18 mounting hole, 20 input rod, 21 connection hole, 22 spring holding hole, 23 brake connector, 25 arm, 26 object to be detected, 27 regulating plate, 30 biasing member, 31 coil spring, 32 retainer, 33 receiving surface, 40 control rod, 41 plate, 42 step portion, 43 coil spring, 44 tip portion, 50 sensor portion, 51 sensor board, 52 position sensor, 60 motor portion, 61 stator, 62 rotor, 63 rotating shaft, 64 bearing, 65 bearing, 66 detection gear, 67 detection gear, 68 motor cover, 70 control portion, 71 control board, 72 RPM sensor, 73 cable, 74 cable, 80 rotary-linear converter, 81 shaft member, 82 rotary member, 83 connecting member, 90 bracket, 91 through hole, 92 through hole, 93 flange bush, 100 support, 101 small diameter portion, 102 large diameter portion, 103 tip portion, 104 nut, 110 return spring, 120 master cylinder, 121 cylinder bore, 122 first output port, 123 second output port, 124 mounting hole, 125 bolt, 126 nut, 127 primary chamber, 128 secondary chamber, 130 first piston, 131 bulkhead, 132 recess, 133 elastic body, 134 coil spring, 135 expandable member, 136 retainer guide, 137 stopper portion, 138 retainer rod, 139 Flange portion, 140 second piston, 141 partition wall, 142 recessed portion, 143, 144 coil spring, 145 expandable member, 146 retainer guide, 147 stopper portion, 148 retainer rod, 149 flange portion, 151 seal member, 152 seal member, 161 seal member, 162 seal member, 210 ball stud, 211 shaft portion, 212 head portion, 213 flange portion, 220 detection object, 221 through hole, 222 one end, 223 other end, 230 ON-OFF sensor, BP brake pedal

Claims

1. An electromechanical brake booster comprising: An input rod connected to the brake pedal; a control rod having a cylindrical detection object attached to its outer circumferential surface and moving linearly in the axial direction in conjunction with the input rod in response to operation of the brake pedal; a sensor unit including a position sensor that detects a displacement of the control rod; a motor section that operates in response to the displacement of the control rod; a control unit that drives the motor unit by using information obtained from the sensor unit; a rotary-to-linear motion conversion unit arranged on an outer periphery of the control rod, the rotary-to-linear motion conversion unit including a shaft member and a rotating member, and interlocking with the motor unit to convert the rotary motion of the rotating member into linear motion of the shaft member; a bracket that restricts the axial rotation of the shaft member and moves in an axial direction in conjunction with the shaft member; A return spring for biasing the bracket to return to its original position after it has been moved; a master cylinder connected to a tip end side of the control rod and the shaft member and operated by linear motion of the control rod or the shaft member, the position sensor is disposed outside the detection object, and the displacement of the detection object is detected by the position sensor, thereby detecting the displacement of the control rod. Electromechanical brake booster.

2. A ball stud is attached to one end of the control rod; The ball stud has a shaft portion, a spherical head portion, and a flange portion formed to protrude between the shaft portion and the head portion, the shank of the ball stud is inserted into a through hole formed in the cylindrical detection object so as to coincide with the axis of the cylindrical detection object, and the detection object is attached so as not to become detached by being held between a flange portion of the ball stud and an end portion of the control rod.

2. An electromechanical brake booster according to claim 1.

3. a biasing member is disposed inside the input rod for biasing the input rod and the control rod in directions separating them from each other to maintain the input rod in a constant position; The input rod and the control rod are connected by crimping.

3. An electromechanical brake booster according to claim 1 or 2.

4. An ON-OFF sensor is attached to the brake pedal and transmits an ON signal when the brake pedal is depressed and an OFF signal when the brake pedal is not depressed. a position of the detected object when an OFF signal is transmitted from the ON-OFF sensor after the engine is started is used as an initial position for correction; 4. An electromechanical brake booster according to claim 1, 2 or 3.

5. the input rod, the control rod, the motor unit, the rotary-linear motion conversion unit, the bracket, and the master cylinder are all coaxially arranged.

2. An electromechanical brake booster according to claim 1.

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