JP2017049063A - Stroke detection device and electric servo device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stroke detection device with which it is possible to detect a stroke amount with high accuracy without extending the length of a movement member, even when the maximum amount of stroke of the movement member increases.SOLUTION: A movement position calculation circuit 80 of a stroke detection device 54, when switching the movement position of an input plunger 29 from a calculation method based on the detection value of a first Hall IC 75A to a calculation method based on the detection value of a second Hall IC 75B, calculates the movement position of the input plunger 29 at that switching point of time on the basis of the detection value of the second Hall IC 75B, and then corrects a difference between the detection value of the first Hall IC 75A and the detection value of the second Hall IC 75B at the switching point of time so as to gradually eliminate it along with the movement of the input plunger 29, and calculates the movement position of the input plunger 29 on the basis of the detection value of the second Hall IC 75B. Thus, it is possible to detect a stroke amount with high accuracy even when the maximum amount of stroke of the input plunger 29 increases.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a stroke detection device that detects a movement position of a moving member, and an electric booster that is incorporated in a vehicle such as an automobile, in which the stroke detection device is incorporated.

  Patent Document 1 discloses a vehicle including a brake assist device that assists a brake pedal by depressing a brake pedal and transmits it to a master cylinder, and a stroke detection device that detects a movement position of an input rod based on an operation amount of the brake pedal. A brake device is described. Then, it is disclosed that this vehicle brake device controls the hydraulic pressure of the brake fluid by the brake assist device based on the operation amount of the brake pedal detected by the stroke detection device and supplies it to the hydraulic pressure control unit. ing.

JP 2015-21745 A

  The stroke detection device employed in the vehicle brake device according to Patent Document 1 described above is a Hall sensor unit in which the magnetic flux density of a plurality of magnetic bodies mounted on the input rod along the axial direction is provided on the casing cover. The configuration to detect is adopted. With this configuration, the stroke amount (movement position) of the input rod is detected. However, in this stroke detection device, when the maximum stroke amount of the input rod increases, it is necessary to increase the length of the input rod, and the device itself becomes large.

  The present invention has been made in view of the above points, and even if the maximum stroke amount of the moving member (input member) is increased, the stroke amount is reduced without increasing the length of the moving member (input member). It is an object of the present invention to provide a stroke detection device and an electric booster that can detect with high accuracy.

  In order to solve the above problems, a stroke detection device according to the present invention is a stroke detection device that detects a movement position of a moving member, and the stroke detection device includes a magnet member attached to the moving member, A plurality of detection elements for detecting a magnetic flux density from the magnet member; and a movement position calculation circuit for calculating a movement position of the movement member based on a detection result from the detection element as the movement member moves. The moving position calculation circuit changes the moving position of the moving member accompanying the movement of the moving member from a calculation method based on the detection value of the one detection element to a calculation method based on the detection value of the other detection element. At the time of switching, after calculating the moving position of the moving member at the switching time based on the detection value of the other detection element, the one detection element at the switching time is moved along with the movement of the moving member. The correction value is corrected so as to gradually eliminate the difference between the detection value of the other detection element and the detection value of the other detection element, and the movement position of the moving member is calculated based on the detection value of the other detection element. .

  An electric booster according to the present invention is connected to an electric motor, an assist mechanism that is driven by the electric motor to propel a piston of a master cylinder, a housing that houses the assist mechanism, and a brake pedal. An input member extending into the housing; a stroke detection device for detecting a stroke of the input member relative to the housing; and a control device for controlling the operation of the electric motor based on the stroke of the input rod. In the electric booster, the stroke detection device includes a magnet member attached to the input member, a plurality of detection elements for detecting a magnetic flux density generated in the magnet member, and the detection as the input member moves. A movement position calculation circuit for calculating a movement position of the input member based on a detection result from the element. When the position calculation circuit switches the movement position of the input member accompanying the movement of the input member from the calculation method based on the detection value of the one detection element to the calculation method based on the detection value of the other detection element, After calculating the movement position of the input member at the time of switching based on the detection value of the other detection element, the detection value of the one detection element and the detection value of the other detection element are moved along with the movement of the input member. The correction is made so that the difference from the detection value is gradually eliminated, and the movement position of the input member is calculated based on the detection values of the other detection elements.

  According to the stroke amount detection device and the electric booster according to the present invention, even if the maximum stroke amount of the moving member (input member) increases, the length of the moving member (input member) is not increased. The enlargement can be suppressed and the stroke amount can be detected with high accuracy.

It is sectional drawing of the electric booster which concerns on embodiment of this invention. It is a schematic diagram of the stroke detection apparatus employ | adopted as the electric booster of FIG. It is the figure which showed the recognition movement position of the input plunger based on the output value of 1st and 2nd Hall IC with respect to time when the brake pedal was depressed calculated by the conventional method. It is a flowchart at the time of calculating the movement position of an input plunger by the movement position calculation circuit of this embodiment with the movement of an input plunger when a brake pedal is depressed. It is the figure which showed the recognition movement position of the input plunger based on the output value of the 1st and 2nd Hall IC with respect to time when the brake pedal was depressed calculated by the movement position calculation circuit of this embodiment. It is a flowchart at the time of calculating the movement position of an input plunger by the movement position calculation circuit of this embodiment with the movement of an input plunger when operation of a brake pedal is cancelled | released. It is the figure which showed the recognition movement position of the input plunger based on the output value of 1st and 2nd Hall IC with respect to time when the operation of a brake pedal was cancelled | released calculated by the movement position calculation circuit of this embodiment. is there.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
The electric booster 1 according to this embodiment is applied to a vehicle brake device such as an electric vehicle or a hybrid electric vehicle. In the following description, the left side is assumed to be the front side (vehicle front side) and the right side is assumed to be the rear side (vehicle rear side) in FIG.

  Referring to FIG. 1, the electric booster 1 according to the present embodiment is roughly a housing 3, an input plunger 29, an electric motor 2, a ball screw mechanism 38, a stroke detection device 54, a controller 55, It has. The input plunger 29 extends into the housing 3 and is connected to the brake pedal 6 via the input rod 30 and constitutes an input member together with the input rod 30. The electric motor 2 is provided in the housing 3. The ball screw mechanism 38 propels the primary piston 10 and the secondary piston 11 of the master cylinder 4 by the operation of the electric motor 2. The ball screw mechanism 38 is configured as an assist mechanism. The stroke detection device 54 detects the movement position (stroke amount) of the input plunger 29 (input rod 30) with respect to the housing 3. The controller 55 is a control device that controls the operation of the electric motor 2 based on the movement position (stroke amount) of the input plunger 29 detected by the stroke detection device 54.

  The electric booster 1 has a structure in which a tandem master cylinder 4 is connected to the front side of the housing 3 (left side in FIG. 1). A reservoir 5 for supplying brake fluid to the master cylinder 4 is attached to the top of the master cylinder 4. The housing 3 includes a front housing 3A that houses the electric motor 2, the ball screw mechanism 38, and the like, and a rear housing 3B that closes the rear end opening (the right end opening in FIG. 1) of the front housing 3A. The rear housing 3B is concentric with the master cylinder 4 and has a cylindrical portion 7 protruding from the rear of the housing 3, that is, in a direction away from the master cylinder 4. A mounting plate 60 is fixed around the cylindrical portion 7 of the rear housing 3B. A plurality of stat bolts 8 are attached to the attachment plate 60. The electric booster 1 is disposed in the engine room with the input rod 30 protruding from a dash panel (not shown) that is a partition wall between the engine room and the vehicle compartment of the vehicle and facing the vehicle interior. And fixed to the dash panel using a plurality of stud bolts 8.

  A bottomed cylinder bore 9 is formed in the master cylinder 4. A substantially cylindrical primary piston 10 is disposed on the opening side of the cylinder bore 9. The front end side of the primary piston 10 is formed in a cup shape and is disposed in the cylinder bore 9. A cup-shaped secondary piston 11 is disposed on the bottom side of the cylinder bore 9. The rear end portion of the primary piston 10 extends from the opening of the master cylinder 4 into the housing 3 and extends into the cylindrical portion 7 of the rear housing 3B. In the cylinder bore 9 of the master cylinder 4, a primary chamber 12 is formed between the primary piston 10 and the secondary piston 11, and a secondary chamber 13 is formed between the bottom of the cylinder bore 9 and the secondary piston 11.

  Each of the primary chamber 12 and the secondary chamber 13 of the master cylinder 4 is a wheel cylinder (not shown) of each wheel via a hydraulic control unit (not shown) by two hydraulic circuits from the hydraulic port of the master cylinder 4. And the brake fluid generated by the master cylinder 4 or the fluid pressure control unit is supplied to the wheel cylinder of each wheel to generate a braking force.

  The master cylinder 4 is provided with reservoir ports 14 and 15 for connecting the primary chamber 12 and the secondary chamber 13 to the reservoir 5, respectively. On the inner peripheral surface of the cylinder bore 9, annular piston seals 16, 17, 18, 19 that abut against the primary piston 10 and the secondary piston 11 are axially arranged in order to partition the inside of the cylinder bore 9 into a primary chamber 12 and a secondary chamber 13. Are arranged at predetermined intervals along the line. The piston seals 16 and 17 are disposed so as to sandwich one reservoir port 14 (rear side) along the axial direction. When the primary piston 10 is in the non-braking position shown in FIG. 1, the primary chamber 12 communicates with the reservoir port 14 via the piston port 20 provided on the side wall of the primary piston 10. When the primary piston 10 moves forward from the non-braking position and the piston port 20 reaches one piston seal 17, the primary chamber 12 is shut off from the reservoir port 14 by the piston seal 17 and a hydraulic pressure is generated.

  Similarly, the remaining two piston seals 18 and 19 are disposed along the axial direction with the reservoir port 15 (front side) interposed therebetween. When the secondary piston 11 is in the non-braking position shown in FIG. 1, the secondary chamber 13 communicates with the reservoir port 15 via a piston port 21 provided on the side wall of the secondary piston 11. Then, the secondary piston 11 moves forward from the non-braking position, and the secondary chamber 13 is shut off from the reservoir port 15 by the piston seal 19 to generate hydraulic pressure.

  A spring 22 is interposed between the primary piston 10 and the secondary piston 11. A spring 23 is interposed between the bottom of the cylinder bore 9 and the secondary piston 11. The primary piston 10 is formed in a substantially cylindrical shape as a whole, and has an intermediate wall 24 in the center in the axial direction. A guide bore 25 passes through the intermediate wall 24 in the axial direction. A part of the input piston 26 is slidably and liquid-tightly inserted into the guide bore 25. The input piston 26 is formed in a stepped shape including a small diameter portion 26A located on the front side and a large diameter portion 26B extending continuously from the small diameter portion 26A to the rear side. A small diameter portion 26 </ b> A of the input piston 26 is slidably and liquid-tightly inserted into the guide bore 25.

  A seal 27 seals the outer peripheral surface of the small diameter portion 26 </ b> A of the input piston 26 and the inner peripheral surface of the guide bore 25 provided on the intermediate wall 24 of the primary piston 10. An outer flange-shaped spring receiving portion 26 </ b> C is formed at the rear end of the large-diameter portion 26 </ b> B of the input piston 26. A guide recess 26 </ b> D is formed on the rear end surface of the input piston 26. The input piston 26 faces the primary chamber 12 of the master cylinder 4 at the front end portion of the small diameter portion 26 </ b> A and can move relative to the primary piston 10 along the axial direction.

  An input plunger 29 is guided behind the input piston 26 inside the rear side of the primary piston 10 so as to be movable along the axial direction. The input plunger 29 includes a shaft portion 29A, an annular portion 29B, a small-diameter protruding portion 29C, a spherical concave portion 29D, and a spring receiving portion 29E. The annular portion 29B protrudes radially outward from the axially rear end of the shaft portion 29A. The small-diameter protruding portion 29C protrudes forward from the front end surface of the shaft portion 29A. The spherical recess 29D is provided on the rear end surface of the shaft portion 29A. The spring receiving portion 29E protrudes rearward from the periphery of the spherical recess 29D. The ball joint 31 at the front end portion of the input rod 30 is connected to the spherical recess 29D of the input plunger 29 so as to allow a certain degree of inclination with respect to the axial direction of the input rod 30. A small-diameter projecting portion 29 </ b> C of the input plunger 29 is disposed in a guide recess 26 </ b> D provided on the rear end surface of the input piston 26.

  The front end side of the input rod 30 connected to the input plunger 29 is disposed inside the cylindrical portion 7 and the primary piston 10 of the rear housing 3B, and the rear end side extends from the cylindrical portion 7 to the outside. The brake pedal 6 is connected to the rear end portion of the input rod 30 via a clevis 30A. And the input rod 30 moves to an axial direction by operation of the brake pedal 6. FIG. In addition, a hook-shaped stopper abutting portion 32 is formed at a substantially intermediate portion of the input rod 30. A stopper 33 extending radially inward is formed at the rear end portion of the cylindrical portion 7, and the retracted position of the input rod 30 is defined by the stopper contact portion 32 of the input rod 30 coming into contact with the stopper 33. It has become so.

  A first spring 34 that is a compression coil spring is interposed between the intermediate wall 24 of the primary piston 10 and a spring receiving portion 26 </ b> C formed at the rear end portion of the input piston 26. A second spring 36, which is a compression coil spring, is interposed between a spring receiving portion 29E provided at the rear end portion of the input plunger 29 and a spring receiver 35 attached to the rear end portion of the primary piston 10. Has been. A cylindrical member 37 is disposed in a cylindrical screw shaft 40 that constitutes a ball screw mechanism 38 to be described later. The cylindrical member 37 has a rear end portion that contacts the front surface of the outer peripheral portion of the spring receiver 35 and extends from the front end of the screw shaft 40 to a position slightly ahead. A spring receiver 37 </ b> A is formed on the front end surface of the cylindrical member 37.

  The input piston 26 and the input plunger 29 are held with respect to the primary piston 10 at the initial position shown in FIG. 1 by the first spring 34 and the second spring 36 when the brake pedal 6 is not operated. That is, the input piston 26 and the input plunger 29 are elastically held at a position where the urging force of the first spring 34 and the urging force of the second spring 36 are balanced with respect to the primary piston 10. The input piston 26 and the input plunger 29 are movable forward and backward from this initial position with respect to the primary piston 10.

  A ball screw mechanism 38 as an assist mechanism is accommodated in the housing 3. The ball screw mechanism 38 is a rotation / linear motion conversion mechanism that is driven by the electric motor 2 disposed in the housing 3 and converts a rotational motion into a linear motion to apply thrust to the primary piston 10. The ball screw mechanism 38 includes a nut member 39 that is a rotating member and a screw shaft 40 that is a linear motion member. The nut member 39 is rotatably supported in the housing 3 by a bearing 42. The bearing 42 is fixed to the rear housing 3B.

  The screw shaft 40 is formed in a cylindrical shape. The screw shaft 40 extends from the inside of the nut member 39 into the cylindrical portion 7 of the housing 3, is movable along the axial direction, and is supported by the housing 3 so as not to rotate around the axis. The screw shaft 40 is urged in the backward direction by the urging force of a return spring 49 which is a compression coil spring interposed between the bottom of the front housing 3A and a spring receiver 37A provided at the front end of the cylindrical member 37. Yes. On the inner peripheral surface of the nut member 39 and the outer peripheral surface of the screw shaft 40, spiral grooves 39A and 40A are formed, respectively. Between these spiral grooves 39A and 40A, a plurality of rolling elements balls 41 are loaded together with grease. The screw shaft 40 is guided by the stopper 33 of the cylindrical portion 7 so as to be movable along the axial direction, and is supported so as not to rotate around the shaft. Thereby, with rotation of the nut member 39, the ball 41 rolls along the spiral grooves 39A, 40A, and the screw shaft 40 moves in the axial direction. The ball screw mechanism 38 is capable of mutually converting rotational-linear motion between the nut member 39 and the screw shaft 40.

  The primary piston 10 has a rear end portion inserted into the screw shaft 40, and a rear surface of the outer peripheral portion of the spring receiver 35 abuts on a stepped portion 44 formed of a plurality of protrusions formed on the inner peripheral portion of the screw shaft 40. The retracted position with respect to the screw shaft 40 is defined. Due to the contact with the step portion 44, the primary piston 10 is pushed forward by the step portion 44 together with the cylindrical member 37 by the advancement of the screw shaft 40. Further, even when the screw shaft 40 does not advance, the primary piston 10 can be moved away from the step portion 44 by the advancement of the input rod 30, the force piston 26, and the input plunger 29.

  The electric motor 2 is housed in the housing 3 on a separate axis from the master cylinder 4, the input rod 30, and the ball screw mechanism 38. A pulley 45 </ b> A is attached to the output shaft 2 </ b> A of the electric motor 2. The output shaft 2A is rotatably supported in the housing 3 by bearings 50 and 51. A pulley 45 </ b> B is attached to the nut member 39 of the ball screw mechanism 38. A belt 46 is wound around the pulley 45A of the output shaft 2A and the pulley 45B of the nut member 39. The electric motor 2 rotates the nut member 39 of the ball screw mechanism 38 via the pulleys 45A and 45B and the belt 46.

  The electric booster 1 includes a rotation position sensor (not shown) that detects the rotation position of the electric motor 2, a stroke detection device 54 that detects the movement position of the input plunger 29 by operating the brake pedal 6, and a master cylinder. A hydraulic pressure sensor (not shown) for detecting hydraulic pressures of the four primary chambers 12 and the secondary chamber 13 is provided. Based on these output signals, the controller 55 controls the operation of the electric motor 2. The controller 55 can be appropriately connected to an in-vehicle controller or the like for executing various brake controls such as regenerative cooperative control, brake assist control, and automatic brake control. In the figure, reference numeral 55A denotes a wiring connector for supplying power to the electric motor 2, the controller 55, and the stroke detecting device 54, and transferring control signals.

  As shown in FIGS. 1 and 2, the stroke detection device 54 includes a plurality of magnet members 70 </ b> A and 70 </ b> B, a hall sensor unit 71, and the hall ICs 75 </ b> A and 75 </ b> B of the hall sensor unit 71 as the input plunger 29 moves. And a movement position calculation circuit 80 for calculating the movement position (stroke amount) of the input plunger 29 based on the detection result from. The plurality of magnet members 70A and 70B, that is, the first and second magnet members 70A and 70B are respectively fixed to the input plunger 29 at intervals along the axial direction, and the magnetic poles are moved along the moving direction of the input plunger 29. Arranged side by side. The first and second magnet members 70 </ b> A and 70 </ b> B are both formed in a ring shape, and are arranged on the outer periphery of both end portions of the input plunger 29 with an interval in the axial direction.

  The hall sensor unit 71 includes a plurality of hall ICs 75A and 75B and a casing 77 that supports the plurality of hall ICs 75A and 75B. The plurality of Hall ICs 75A and 75B, that is, the first and second Hall ICs 75A and 75B are supported by the casing 77 at intervals along the axial direction. The casing 77 is attached to the master cylinder 4 inserted into the housing 3, and the first and second Hall ICs 75A and 75B are connected to the first and second magnet members 70A and 70B via the peripheral wall of the rear part of the primary piston 10. It arrange | positions so that it may oppose. The hall sensor unit 71 detects the magnetic flux density across the hall ICs 75A and 75B by the movement of the first and second magnet members 70A and 70B that move together with the input plunger 29, and the input plunger 20 (first and second magnets). A voltage signal is output in accordance with the movement of the members 70A and 70B).

  As will be described in detail later, the movement position of the input plunger 20 is calculated by the movement position calculation circuit 80 based on detection signals from the Hall ICs 75A and 75B. The first and second Hall ICs 75A and 75B can detect the magnetic flux density of at least one of the first and second magnets 70A and 70B regardless of the position of the input plunger 29 that is moved by the operation of the brake pedal 6. Is arranged. The first Hall IC 75A corresponds to one detection element, and the second Hall IC 75B corresponds to another detection element.

Next, an operation when the electric booster 1 is energized will be described.
FIG. 1 shows an initial position in a non-braking state where the input rod 30 and the screw shaft 40 of the ball screw mechanism 38 are in the most retracted position. When the input pedal 30 is moved forward by operating the brake pedal 6, the stroke detection device 54 detects the operation amount of the brake pedal 6 (the movement position of the input rod 30 and the input plunger 29). Specifically, the movement position calculation circuit 80 moves the movement position of the input plunger 29 based on the voltage signal output from each Hall IC 75A, 75B according to the movement of the first and second magnet members 70A, 70B attached to the input plunger 29. Is detected. The controller 55 controls the operation of the electric motor 2 based on the movement position of the input plunger 29 (input rod 30). The signal output from the Hall IC 75 may be a voltage signal, a current signal, a digital signal, or the like.

  By rotating the nut member 39 of the ball screw mechanism 38 via the pulleys 45A and 45B and the belt 46 by the electric motor 2, the screw shaft 40 is advanced. Then, the spring receiver 35 of the primary piston 10 is pressed by the step 44 of the screw shaft 40, and the primary piston 10 moves forward to follow the stroke of the input rod 30. Thereby, a hydraulic pressure is generated in the primary chamber 12, and this hydraulic pressure is transmitted to the secondary chamber 13 through the secondary piston 11. In this way, the brake fluid pressure generated in the master cylinder 4 is supplied to the wheel cylinder of each wheel, and a braking force is generated by friction braking.

  When the operation of the brake pedal 6 is released, the controller 55 reversely rotates the electric motor 2 based on the movement position of the input plunger 29 (input rod 30) detected by the stroke detection device 54, whereby the primary piston 10 and the secondary piston The piston 11 moves backward, the brake fluid pressure in the master cylinder 4 is reduced, and the braking force is released.

  When the hydraulic pressure is generated, the hydraulic pressure in the primary chamber 12 is received by the small diameter portion 26 </ b> A of the input piston 26, and the reaction force is transmitted to the brake pedal 6 via the input plunger 29 and the input rod 30. As a result, it is possible to execute boost control that generates a desired braking force at a predetermined boost ratio (ratio of hydraulic pressure output to operating force of the brake pedal 6). FIG. 2 shows a state in which the screw shaft 40 of the ball screw mechanism 38 has advanced following the stroke of the input piston 26 by the boost control.

  And the controller 55 can control the action | operation of the electric motor 2, and can adjust the relative position of the input piston 26 and the primary piston 10 which follows this. Specifically, the hydraulic pressure output for the operation of the brake pedal 6 is increased by adjusting the position of the primary piston 10 to the front, that is, the master cylinder 4 side with respect to the stroke position of the input piston 26, That is, the hydraulic pressure output for the operation of the brake pedal 6 can be reduced by adjusting to the brake pedal 6 side. At this time, by the action of the first spring 34 and the second spring 36, the fluctuation of the reaction force to the brake pedal 6 due to the fluctuation of the hydraulic pressure output is suppressed. As a result, in addition to the boost control, brake control such as brake assist control, automatic brake control, inter-vehicle control, and regenerative cooperative control can be executed.

Next, based on the voltage signal output from the first and second Hall ICs 75A and 75B according to the movement of the first and second magnet members 70A and 70B attached to the input plunger 29, the movement position calculation circuit 80 causes the brake pedal to A method of calculating the operation amount 6 (movement position of the input blanker 29) will be described with reference to FIGS.
The movement position calculation circuit 80 basically detects the magnetic flux density of at least one of the first and second magnet members 70A and 70B by at least one of the Hall ICs 75A and 75B, and determines the movement position of the input plunger 29. The first magnet member from the second Hall IC 75B is determined from a method of calculating the moving position of the input plunger 29 based on, for example, an output value corresponding to the magnetic flux density of the first magnet member 70A from the first Hall IC 75A. It is necessary to switch to a method of calculating with an output value corresponding to a magnetic flux density of 70A.

  Therefore, in FIGS. 3, 5, and 7, the solid line indicates the recognized movement position of the input plunger 29 based on the output values of the first and second Hall ICs 75 </ b> A and 75 </ b> B when the input plunger 29 is moving at a constant speed in the axial direction. The broken line indicates the output value of the magnetic flux density from the first magnet member 70A by the second Hall IC 75B with respect to time, while the alternate long and short dash line from the first magnet member 70A by the first Hall IC 75A with respect to time. The output value of the magnetic flux density is shown. 3, 5, and 7, for example, when the first magnet member 70 </ b> A comes close to the first Hall IC 75 </ b> A, the output value of the first Hall IC 75 </ b> A with respect to time increases and the measurement sensitivity is improved, and the first magnet member 70 </ b> A is improved. As the distance from the first Hall IC 75A increases, the output value of the first Hall IC 75A with respect to time decreases, and the measurement sensitivity decreases.

  Therefore, as shown in FIG. 3, at the time of switching, that is, the axial distance between the first Hall IC 75A and the first magnet member 70A and the axial distance between the second Hall IC 75B and the first magnet member 70A. Even when the distance is the same, the first Hall IC 75A and the second Hall IC 75B have their own measurement sensitivities. Therefore, the recognition movement position of the input plunger 29 based on the output value of the first Hall IC 75A, and the second The recognition movement position of the input plunger 29 based on the output value of the Hall IC 75B is different. For this reason, at the time of switching, the first Hall IC 75A cannot be simply switched to the second Hall IC 75B, and the difference between the output value of the first Hall IC 75A and the output value of the second Hall IC 75B at the time of switching is calculated. If the movement position of the input plunger 29 is calculated by correcting in addition to the output value of the second Hall IC 75B after switching, the error with respect to the movement position increases with the movement of the input plunger 29 after switching. I can't.

  In view of this problem, the movement position of the input plunger 29 based on the output value of the first Hall IC 75A with respect to time and the movement position of the input plunger 29 based on the output value of the second Hall IC 75B with respect to time are substantially collinear. So that there is no step difference at the time of switching (difference in the recognized movement position of the input plunger 29 by the first and second Hall ICs 75A and 75B), the first or second hole. It was necessary to correct the movement position of the input plunger 29 based on the output value of the IC 75A or 75B.

  In the present embodiment, first, a method of calculating the movement position of the input blanker 29 by the movement position calculation circuit 80 when the brake pedal 6 is depressed will be described with reference to FIGS. 4 and 5. The first and second Hall ICs 75A and 75B calculate the moving position of the input blanker 29 based on the output value of the magnetic flux density from the first magnet member 70A, and the first and second Hall ICs 75A and 75B. Since the method of calculating the movement position of the input blanker 29 based on the output value of the magnetic flux density from the two magnet members 70B is the same, the magnetic flux density from the first magnet member 70A of the first and second Hall ICs 75A and 75B is the same. A method for calculating the movement position of the input blanker 29 based on the output value will be described below.

  With reference to FIGS. 4 and 5, first, in step S1, it is determined whether or not the process of switching the detection of the magnetic flux density from the first magnet member 70A from the first Hall IC 75A to the second Hall IC 75B is in progress. . This determination is made based on whether or not the switching flag is “0”. If it is determined in step S1 that the switching process is not being performed (No), that is, the switching flag is “0”, the process proceeds to step S2, while the switching process is being performed (Yes). If it is determined that the switching flag is “1”, the process proceeds to step S11.

  In step S2, the switching point for switching from the calculation method based on the output value of the magnetic flux density of the first magnet member 70A by the first Hall IC 75A to the calculation method based on the output value of the magnetic flux density of the first magnet member 70A by the second Hall IC 75B. It is determined whether or not. The determination at this step S2 is shown in FIG. 5 with respect to time, the output value (broken line) of the magnetic flux density from the first magnet member 70A by the second Hall IC 75B with respect to time, and the first magnet member by the first Hall IC 75A with respect to time. It is determined based on whether or not the output value (one-dot chain line) of the magnetic flux density from 70A is substantially parallel (time b1 to time b2). Then, if it is determined that both are substantially parallel (Yes), the process proceeds to step S3. On the other hand, if it is determined that both are not approximately parallel (No), the process proceeds to step S8.

  In step S3, the switching flag is set to “1”. Subsequently, in step S4, the switching point flag is set to “1”. Subsequently, in step S5, the output value S1 of the magnetic flux density of the first magnet member 70A by the first Hall IC 75A and the output value S2 of the magnetic flux density of the first magnet member 70A by the second Hall IC 75B at the switching point b. The difference ΔSt is calculated. Subsequently, in step S6, the movement position X1 of the input plunger 29 is calculated from the output value S1 of the magnetic flux density of the first magnet member 70A by the first Hall IC 75A at the switching point b, and the movement of the input plunger 29 at the switching point b. A difference ΔSf between the position X1 and the output value S2 of the magnetic flux density of the first magnet member 70A by the second Hall IC 75B is calculated. In step S7, the movement position X1 ′ (= X1) of the input plunger 29 immediately after the switching point b is calculated by adding ΔSf to the output value S2 of the magnetic flux density of the first magnet member 70A by the second Hall IC 75B. .

  In step S8, it is determined whether or not the switching point flag is “0”. When it is determined that the switching point flag is “0” (Yes), the process proceeds to step S9, where calculation based on the output value S1 of the magnetic flux density of the first magnet member 70A by the first Hall IC 75A is performed. The moving position X of the input plunger 29 is calculated by the method. Specifically, the moving position X of the input plunger 29 is calculated by adding or subtracting a predetermined value α to or multiplying the output value S1 of the magnetic flux density of the first magnet member 70A by the first Hall IC 75A or by multiplying the predetermined coefficient α. . On the other hand, if it is determined in step S8 that the switching point flag is “1” (No), the process proceeds to step S10, and in step S10, the magnetic flux density of the first magnet member 70A is output by the second Hall IC 75B. The movement position X of the input plunger 29 is calculated by a calculation method based on the value S2. Specifically, the movement position X of the input plunger 29 is calculated by adding or subtracting a predetermined value α ′ to the output value S2 of the magnetic flux density of the first magnet member 70A by the second Hall IC 75B, or multiplying by a predetermined coefficient α ′. The

  Next, in step S11, the difference between ΔSt calculated in step S5 and the output value S2 of the magnetic flux density of the first magnet member 70A by the second Hall IC 75B accompanying the movement of the input plunger 29 is the movement of the input plunger 29. A value ΔS divided by half of the speed is calculated. Subsequently, in step S12, ΔS calculated in step S11 is added to the output value S2 of the magnetic flux density of the first magnet member 70A by the second Hall IC 75B accompanying the movement of the input plunger 29 to move the input plunger 29. X is calculated.

Next, in step S13, the movement position X of the input plunger 29 calculated in step S12 is equal to or greater than the value obtained by adding ΔSt calculated in step S5 to the movement position X1 of the input plunger 29 at the switching point b calculated in step S7. It is determined whether or not. If YES is determined in step S13, the correction section (correction section a in FIG. 5) is completed, the process proceeds to step S14, and the switching flag is set to “0” in step S14. . On the other hand, if it is determined No in step S13, it is still in the correction section (in the correction section a in FIG. 5), and the process proceeds to return.
Referring to FIG. 5, when the brake pedal 6 is depressed, the recognized movement position of the input plunger 29 based on the output value of the first Hall IC 75A with respect to time and the input based on the output value of the second Hall IC 75B with respect to time. It can be seen that the recognized movement position of the plunger 29 changes in substantially the same straight line.

Next, a method for calculating the movement position of the input blanker 29 by the movement position calculation circuit 80 when the operation of the brake pedal 6 is released will be described with reference to FIGS.
With reference to FIGS. 6 and 7, first, in step S51, it is determined whether or not the process of switching the detection of the magnetic flux density from the first magnet member 70A from the second Hall IC 75B to the first Hall IC 75A is in progress. . This determination is made based on whether or not the switching flag is “0”. If it is determined in step S51 that the switching process is not in progress (No), that is, if the switching flag is “0”, the process proceeds to step S52, while the switching process is in progress (Yes). If it is determined that the switching flag is “1”, the process proceeds to step S61.

  In step S52, the switching point for switching from the calculation method based on the output value of the magnetic flux density of the first magnet member 70A by the second Hall IC 75B to the calculation method based on the output value of the magnetic flux density of the first magnet member 70A by the first Hall IC 75A. It is determined whether or not. The determination in step S2 is as shown in FIG. 7, in which the output value (broken line) of the magnetic flux density from the first magnet member 70A by the second Hall IC 75B with respect to time and the first magnet member by the first Hall IC 75A with respect to time. It is determined based on whether or not the output value (one-dot chain line) of the magnetic flux density from 70A is substantially parallel (time b1 to time b2). Then, if it is determined that both are substantially parallel (Yes), the process proceeds to step S53, while if it is determined that both are not approximately parallel (No), the process proceeds to step S58.

  In step S53, the switching flag is set to “1”. Subsequently, in step S54, the switching point flag is set to “0”. Subsequently, in step S55, the output value S2 of the magnetic flux density of the first magnet member 70A by the second Hall IC 75B and the output value S1 of the magnetic flux density of the first magnet member 70A by the first Hall IC 75A at the switching point b. The difference ΔSt is calculated. Subsequently, in step S56, the movement position X2 of the input plunger 29 is calculated from the output value S2 of the magnetic flux density of the first magnet member 70A by the second Hall IC 75B at the switching point b, and the movement of the input plunger 29 at the switching point b. A difference ΔSf between the position X2 and the output value S1 of the magnetic flux density of the first magnet member 70A by the first Hall IC 75A is calculated. In step S57, the movement position X2 ′ (= X2) of the input plunger 29 immediately after the switching point b is calculated by adding ΔSf to the output value S1 of the magnetic flux density of the first magnet member 70A by the first Hall IC 75A. .

  In step S58, it is determined whether or not the switching point flag is “1”. If it is determined that the switching point flag is “1” (Yes), the process proceeds to step S59, and the input plunger is calculated by a calculation method based on the output value S2 of the magnetic flux density of the first magnet member 70A by the second Hall IC 75B. 29 movement positions X are calculated. Specifically, the moving position of the input plunger 29 is calculated by adding or subtracting a predetermined value α to or multiplying the output value S2 of the magnetic flux density of the first magnet member 70A by the second Hall IC 75B, or by multiplying by a predetermined coefficient α. On the other hand, if it is determined in step S58 that the switching point flag is “0” (No), the process proceeds to step S60, and the calculation based on the output value S1 of the magnetic flux density of the first magnet member 70A by the first Hall IC 75A. The moving position X of the input plunger 29 is calculated by the method. Specifically, the moving position X of the input plunger 29 is calculated by adding or subtracting a predetermined value α ′ to the output value S1 of the magnetic flux density of the first magnet member 70A by the first Hall IC 75A, or multiplying by a predetermined coefficient α ′. The

  Next, in step S61, the difference between ΔSt calculated in step S55 and the output value S1 of the magnetic flux density of the first magnet member 70A by the first Hall IC 75A accompanying the movement of the input plunger 29 is used as the movement of the input plunger 29. A value ΔS divided by half of the speed is calculated. Subsequently, in step S62, ΔS calculated in step S61 is subtracted from the output value S1 of the magnetic flux density of the first magnet member 70A by the first Hall IC 75A accompanying the movement of the input plunger 29, and the movement position of the input plunger 29 is subtracted. X is calculated.

Next, in step S63, the movement position X of the input plunger 29 calculated in step S62 is equal to or less than the value obtained by subtracting ΔSt calculated in step S55 from the movement position X2 of the input plunger 29 at the switching point b calculated in step S57. It is determined whether or not. If YES is determined in step S63, the correction section (correction section a in FIG. 7) is completed, the process proceeds to step S64, and the switching flag is set to “0” in step S64. . On the other hand, if it is determined No in step S63, it is still in the correction section (in the correction section a in FIG. 7), and the process proceeds to return.
Referring to FIG. 7, when the operation of the brake pedal 6 is released, the recognized movement position of the input plunger 29 based on the output value of the first Hall IC 75A with respect to time and the output value of the second Hall IC 75B with respect to time. It can be seen that the recognized movement position of the input plunger 29 based on the input plunger 29 changes in substantially the same straight line.

  As described above, the stroke detection device 54 provided in the electric booster 1 according to the present embodiment is input based on the detection results from the first and second Hall ICs 75A and 75B as the input plunger 29 moves. A movement position calculation circuit 80 for calculating the movement position of the plunger 29 is provided. The movement position calculation circuit 80 determines the movement position of the input plunger 29 accompanying the movement of the input plunger 29, for example, when the brake pedal 6 is depressed. When switching from the calculation method based on the output value of the first Hall IC 75A to the calculation method based on the output value of the second Hall IC 75B, the movement position of the input plunger 29 at the time of switching is calculated based on the output value of the second Hall IC 75B. After that, the movement position of the input plunger 29 in the correction section a (see FIG. 5) from the switching time is the input position. An arithmetic expression based on the output value S2 of the second Hall IC 75B accompanying the movement of the ranger 29, the difference ΔSt between the output value of the first Hall IC 75A and the output value of the second Hall IC 75B at the time of switching, and the moving speed of the input plunger 29 It is made to calculate with.

  Thereby, even when the maximum stroke amount of the input plunger 29 increases, the stroke amount can be detected without increasing the length of the input plunger 29 by increasing the number of Hall ICs 75A and 75B. Moreover, by the calculation method of the movement position calculation circuit 80 provided in the stroke detection device 54, the recognized movement position of the input plunger 29 based on the output value of the first Hall IC 75A with respect to time and the output value of the second Hall IC 75B with respect to time. Therefore, the movement position (stroke amount) of the input plunger 29 can be detected with high accuracy.

  In the present embodiment, the stroke detection device 54 is incorporated in the electric booster 1 as means for detecting the movement position of the input plunger 29 of the electric booster 1. The stroke detection device 54 can be configured alone as means for detecting the movement position of the corresponding moving member.

  In the present embodiment, two first and second magnet members 70A and 70B are provided, but three or more may be provided. Similarly, three or more first and second Hall ICs 75A and 75B may be provided. Good.

  DESCRIPTION OF SYMBOLS 1 Electric booster, 2 Electric motor, 3 Housing, 4 Master cylinder, 10 Primary piston, 29 Input plunger (input member, moving member), 38 Ball screw mechanism (assist mechanism), 54 Stroke detection device, 55 Controller (control device) ), 70A First magnet member, 70B Second magnet member, 71 Hall sensor unit, 75A First Hall IC (detection element), 75B Second Hall IC (detection element), 80 Moving position calculation circuit

Claims (3)

A stroke detecting device for detecting a moving position of a moving member,
The stroke detection device comprises:
A magnet member mounted on the moving member;
A plurality of detecting elements for detecting a magnetic flux density from the magnet member;
A moving position calculation circuit that calculates a moving position of the moving member based on a detection result from the detection element as the moving member moves,
The movement position calculation circuit switches the movement position of the moving member accompanying the movement of the moving member from a calculation method based on the detection value of the one detection element to a calculation method based on the detection value of the other detection element. In this case, after calculating the movement position of the moving member at the switching time based on the detection value of the other detection element, the detection value of the one detection element at the switching time and the other are calculated along with the movement of the moving member. A stroke detection device, wherein the difference between the detection element and the detection value of the detection element is corrected so as to be gradually eliminated, and the movement position of the moving member is calculated based on the detection value of another detection element.   The movement position of the moving member in the correction section from the switching time point is the detection value of the other detection element accompanying the movement of the moving member, the detection value of the one detection element at the switching time point, and the detection value of the other detection element. The stroke detection device according to claim 1, wherein the stroke detection device is calculated by an arithmetic expression based on a difference from a detection value and a moving speed of the moving member. An electric motor, an assist mechanism that is driven by the electric motor to propel the piston of the master cylinder, a housing that houses the assist mechanism, an input member that is connected to a brake pedal and extends into the housing, and the housing In the electric booster comprising: a stroke detection device for detecting the stroke of the input member; and a control device for controlling the operation of the electric motor based on the stroke of the input rod.
The stroke detection device includes a magnet member attached to the input member, a plurality of detection elements for detecting a magnetic flux density generated by the magnet member, and a detection result from the detection element as the input member moves. A movement position calculation circuit for calculating a movement position of the input member based on
The movement position calculation circuit switches the movement position of the input member accompanying the movement of the input member from a calculation method based on the detection value of the one detection element to a calculation method based on the detection value of the other detection element. In this case, after calculating the movement position of the input member at the switching time based on the detection value of the other detection element, the detection value of the one detection element and the other detection are detected along with the movement of the input member. An electric booster characterized by correcting so that a difference from a detected value of an element is gradually eliminated, and calculating a movement position of the input member based on a detected value of another detecting element.

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