JP2008309516A - Tension sensor, and electric parking brake device for vehicle adopting tension sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress deterioration of detection accuracy caused by manufacture accuracy of a compression coil spring which is a component of a tension sensor. <P>SOLUTION: This tension sensor TS is equipped with a spring case 51, a shaft 52, the compression coil spring 53, and a magnet case 55, and also equipped with a detection element 61 provided on the spring case 51, and a magnet 62 provided on the magnet case 55. In the tension sensor TS, when the compression coil spring 53 is compressed and deformed by application of a tensile force in the axial direction, the magnet 62 and the detection element 61 are moved relatively, and the tensile force can be detected. A prescribed amount of radial-direction clearance is provided between the shaft 52 and a mounting hole 51a of the spring case 51, and a prescribed amount of radial-direction clearance is provided between the shaft 52 and a support hole 55a of the magnet case 55. Guide means 56, 59 for moving the magnet case 55 in the setting direction to the spring case 51 are provided between the spring case 51 and the magnet case 55. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a tension sensor capable of detecting a tensile force acting on a cable or the like, and an electric parking brake device for a vehicle that employs the tension sensor.

As one of the electric parking brake devices for a vehicle that employs a tension sensor, an electric motor, a conversion mechanism that converts a rotational driving force of the electric motor into a linear driving force, and an output portion of the conversion mechanism are connected to the linear motor. A cable for transmitting a driving force to the parking brake; a tension sensor capable of detecting a tensile force acting on the cable; and an electric control device for controlling the rotational drive of the electric motor. The cable is pulled by the rotational drive so that the parking brake is released from the release state, and the cable is released by the reverse rotation drive of the electric motor, and the parking brake is released from the brake state. (For example, refer to Patent Document 1).
Japanese Patent Laid-Open No. 2004-161101

  In the electric parking brake device disclosed in the above publication, as a tension sensor capable of detecting a tensile force acting on the cable, a part of the spring is assembled in a mounting hole provided in a spring case so as to be movable in the axial direction. A shaft (described as a rod in the above publication) that is accommodated in the case and protrudes out of the spring case, is coaxially disposed on the outer periphery of the portion of the shaft inside the case, and is engaged with the spring case at one end. A compression coil spring that engages with the shaft at the other end, a magnet case that is assembled with a support hole on the outer periphery of the shaft and that can move integrally with the shaft in the axial direction and supports the magnet; A movement amount detecting means (a magnet and a magnet) is integrally assembled with the spring case and the magnet. A detecting element that constitutes a means for detecting the relative movement amount of the output element), and when the compression coil spring is compressed and deformed by an axial tensile force acting between the spring case and the shaft, A magnet and a detecting element that can move relative to each other to detect the tensile force are employed.

  In the above tension sensor, the shaft is assembled so as to be movable in the axial direction with respect to the spring case. Therefore, in order to reduce the sliding resistance between the shaft and the spring case, the mounting hole provided in the spring case and the shaft It is necessary to provide a certain amount of clearance between the outer peripheries (a clearance for ensuring smooth axial movement of the shaft), but the magnet case can move integrally with the shaft in the axial direction. It is not necessary to provide the above-described gap between the support hole and the outer periphery of the shaft.

  Therefore, if a predetermined amount of clearance is provided between the mounting hole provided in the spring case and the outer periphery of the shaft, and the above-described clearance is not provided between the support hole of the magnet case and the outer periphery of the shaft, each compression coil spring The shaft is inclined with respect to the spring case due to the fact that the axial end face is not formed at right angles to the axis of the compression coil spring and their parallelism is poor (production accuracy of the compression coil spring). The inclination of the shaft may cause unexpected relative movement between the magnet and the detection element, which may deteriorate the detection accuracy of the tensile force. If the compression coil spring is configured to be freely rotatable on the outer periphery of the shaft, the inclination of the shaft changes according to the rotation of the compression coil spring.

  The present invention has been made to cope with the above-mentioned problems, and is assembled in a mounting hole provided in the spring case so as to be movable in the axial direction, and a part thereof is accommodated in the spring case, and the remaining part is the spring. A shaft projecting out of the case, a compression coil spring coaxially disposed on the outer periphery of the portion of the case inside the shaft, engaged with the spring case at one end, and engaged with the shaft at the other end; A magnet case that is assembled with a support hole on the outer periphery and can move integrally with the shaft in the axial direction and supports the magnet, and a movement amount detecting means is integrally assembled with the spring case and the magnet. A detecting element for constituting the compression coil, and an axial tensile force acts between the spring case and the shaft to compress the compression coil; In the tension sensor that can detect the tensile force by the relative movement of the magnet and the detection element when the pulling is compressively deformed, a predetermined amount of radial clearance is provided between the shaft and the mounting hole of the spring case. A required amount of radial clearance is provided between the shaft and the support hole of the magnet case, and guide means for moving the magnet case in a set direction with respect to the spring case is provided between the spring case and the magnet case. There is a special feature.

  In this case, the magnet case is assembled to the outer periphery of the shaft in a state where the magnet case is elastically engaged with the seat surface of the annular sheet integrally assembled to the outer periphery of the shaft, The seating surface can also be formed in a spherical shape centered on the axis of the shaft. The guide means includes a guide pin that is integrally fixed to the spring case or the magnet case and extends in a setting direction, and a shaft of the guide pin provided on the outer periphery of the guide pin provided in the magnet case or the spring case. It is also possible to provide a guide hole that is slidably fitted along the direction.

  In the tension sensor of the present invention described above, the axial end faces of the compression coil spring are not formed at right angles to the axis of the compression coil spring, and the shaft is Even if the shaft tilts with respect to the spring case, the tilt of the shaft is absorbed by the shaft tilting in the support hole of the magnet case whose moving direction is regulated by the guide means with respect to the spring case. . For this reason, the magnet case hardly tilts with respect to the spring case even if the shaft tilts with respect to the spring case due to the poor parallelism of the axial end face of the compression coil spring. Is possible. Therefore, it is possible to reduce the unexpected relative movement (according to the tilting of the magnet case with respect to the spring case) that occurs between the magnet provided in the magnet case and the detection element provided in the spring case. It is possible to suppress the deterioration of force detection accuracy.

  Further, the present invention provides a shaft that is assembled in a mounting hole provided in a spring case so as to be movable in the axial direction, a part of which is accommodated in the spring case, and a remaining part projects out of the spring case, A compression coil spring coaxially disposed on the outer periphery of the inner portion of the case and engaged with the spring case at one end and engaged with the shaft at the other end, and a support hole assembled to the outer periphery of the shaft A detection element case that can move integrally with the shaft in the axial direction and supports the detection element, and a magnet that is integrally assembled with the spring case and constitutes a moving amount detection means by the detection element, When the compression coil spring is compressed and deformed by an axial tensile force acting between the spring case and the shaft, the magnet In the tension sensor in which the detection element is relatively moved and the tensile force can be detected, a predetermined amount of radial clearance is provided between the shaft and the mounting hole of the spring case, and the shaft and the detection element case A required amount of radial clearance is provided between the support holes, and guide means for moving the detection element case in a set direction with respect to the spring case is provided between the spring case and the detection element case.

  In this case, the detection element case is assembled to the outer periphery of the shaft in a state in which the detection element case is elastically engaged with the seat surface of the annular sheet integrally assembled to the outer periphery of the shaft. The seating surface may be formed in a spherical shape centered on the shaft axis. The guide means includes a guide pin that is integrally fixed to the spring case or the detection element case and extends in a setting direction, and the guide pin that is provided on the detection element case or the spring case and is arranged on an outer periphery of the guide pin. It is also possible to provide a guide hole that is slidably fitted along the axial direction.

  In the tension sensor of the present invention described above, the axial end faces of the compression coil spring are not formed at right angles to the axis of the compression coil spring, and the shaft is Even if the shaft tilts with respect to the spring case, the tilt of the shaft is absorbed by the shaft tilting in the support hole of the detection element case whose moving direction is regulated by the guide means with respect to the spring case. The For this reason, even if the shaft tilts with respect to the spring case due to poor parallelism of the axial end face of the compression coil spring, the detection element case is hardly tilted with respect to the spring case. Is possible. Therefore, it is possible to reduce the unexpected relative movement between the detection element provided in the detection element case and the magnet provided in the spring case (according to the tilt of the detection element case with respect to the spring case). It is possible to suppress the accompanying deterioration in detection accuracy of the tensile force.

  And an electric motor, a conversion mechanism that converts the rotational driving force of the electric motor into a linear driving force, a cable that is connected to an output unit of the conversion mechanism and transmits the linear driving force to a parking brake, and A tension sensor capable of detecting a tensile force acting on the cable and an electric control device for controlling the rotational drive of the electric motor are provided. The parking brake is released when the cable is pulled by the forward rotation of the electric motor. In the electric parking brake device for a vehicle configured such that the cable is released by the reverse rotation driving of the electric motor and the parking brake is released from the braking state, the tension sensor is set as the tension sensor. It is also possible to employ the tension sensor described above. In this case, it is possible to improve the detection accuracy of the tensile force acting on the cable.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an electric parking brake device for an automobile embodying the present invention. The electric parking brake device decelerates and transmits a rotational driving force, which is an output of an electric motor 11, and the deceleration mechanism. The conversion mechanism B that converts the rotational driving force of the electric motor 11 transmitted through the mechanism A into a linear driving force, and the linear driving force that is driven by the linear driving force converted by the conversion mechanism B and outputs two linear driving forces. An equalizer 12 is provided for distribution to the sections.

  In addition, the electric parking brake device is connected to the output portions 12 a and 12 b of the equalizer 12 to transmit a linear driving force to the parking brakes 13 and 14, and an inner wire 15 a in one cable 15. A tension sensor TS capable of detecting a tensile force acting on the electric motor 11 and an electric control unit ECU for controlling the rotational drive of the electric motor 11 are provided.

  A one-way power transmission mechanism (not shown) may be interposed in a rotational drive transmission system between the electric motor 11 and the conversion mechanism B (for example, a connecting portion between the speed reduction mechanism A and the conversion mechanism B). The one-way power transmission mechanism transmits the rotational driving force from the electric motor 11 to the conversion mechanism B, but blocks the transmission of the rotational driving force from the conversion mechanism B to the electric motor 11, and stops the forward rotation driving of the electric motor 11. Sometimes the braking state of the parking brakes 13, 14 can be maintained.

  The operation of the electric motor 11 is controlled by the electric control unit ECU. When the driver operates the brake switch SW1, the electric motor 11 is rotated in the forward direction, and when the driver operates the release switch SW2. It is driven to rotate in the reverse direction. The speed reduction mechanism A includes an input gear 21, an intermediate large gear 22, an intermediate small gear 23, and an output gear 24, and is incorporated in a housing portion between a housing 31 and a casing 32 assembled on one side of the housing 31. ing.

  The input gear 21 is formed on the output shaft 11a of the electric motor 11 and rotates integrally with the output shaft 11a. The intermediate large gear 22 is rotatably mounted on a support shaft 33 supported by the housing 31 and the casing 32, and always meshes with the input gear 21. The intermediate small gear 23 is formed integrally with the intermediate large gear 22, is rotatably mounted on the support shaft 33, and is always meshed with the output gear 24. The output gear 24 is assembled to the end of the screw shaft 41 so that torque can be transmitted.

  The conversion mechanism B has a configuration in which a screw shaft 41 that is coaxially and integrally connected to the output gear 24 is used as an input element, and a nut 42 that is screwed and assembled to the screw shaft 41 is used as an output element. And the nut 42 is moved in the axial direction of the screw shaft 41 from the release position (shown position) on the right side of FIG. 1 toward the braking position on the left side of FIG. Further, when the screw shaft 41 is rotationally driven in the opposite direction, the nut 42 is moved in the axial direction of the screw shaft 41 toward the release position on the right side of FIG.

  The screw shaft 41 is arranged with the moving direction of the cables 15 and 16 as the axial direction, and has two trapezoidal male screws (the number and shape of the male screws can be changed as appropriate). It is assembled so as to be immovable and rotatable in the axial direction. The nut 42 is connected to the equalizer 12 via the connecting pin 43 and supports the equalizer 12 so as to be able to swing (rotate around the connecting pin 43).

  The equalizer 12 distributes the linear driving force acting on the nut 42 equally to the two output portions, and is pivotally assembled to the nut 42 at the center thereof. The equalizer 12 is connected to one end of the inner wire 15a in one cable 15 via the tension sensor TS at the arm portion 12a as one output portion, and at the arm portion 12b as the other output portion, The other cable 16 is directly connected to one end of the inner wire 16a.

  One cable 15 is composed of an inner wire 15a and an outer tube 15b that covers the outer periphery other than both ends of the inner wire 15a. The other end of the inner wire 15a is an operating portion of one parking brake 13. It is connected to. The other cable 16 is composed of an inner wire 16a and an outer tube 16b that covers the outer periphery other than both ends of the inner wire 16a. The other end of the inner wire 16a is an operating portion of the other parking brake 14. It is connected to.

  The tension sensor TS detects the tensile force of the inner wire 15a in the cable 15 and outputs it to the electric control unit ECU. As shown in detail in FIGS. 2 to 4, the spring case 51 and the shaft 52 are provided. And a pair of large and small compression coil springs 53, 54. The tension sensor TS includes a magnet case 55, a guide pin 56, and a tension coil spring 57.

  The spring case 51 includes a lower case 51A and an upper case 51B fixed to the upper portion of the lower case 51A. The lower case 51A has a mounting hole 51a (see FIG. 3) for assembling the shaft 52 so as to be movable in the axial direction, and a notch 51b (see FIGS. 2 and 3) for assembling one end of the inner wire 15a. And a pair of large and small compression coil springs 53 and 54 are accommodated therein. The attachment hole 51a of the lower case 51A has a predetermined amount larger than the outer diameter of the shaft 52, and a predetermined amount of radial clearance (to ensure smooth axial movement of the shaft 52) between the shaft 52 and the attachment hole 51a. Gap).

  The upper case 51B has a locking portion 51c for the tension coil spring 57 and a pair of arm portions 51d each including a Hall IC element (detection element) 61, and includes a compression coil spring 53 for the lower case 51A, The part which accommodates 54 is covered. The lower case 51A and the upper case 51B are provided with attachment holes 51e for fitting and fixing the guide pins 56.

  The shaft 52 is assembled in the middle portion so as to be movable in the axial direction in the mounting hole 51a of the lower case 51A. A part of the shaft 52 is accommodated in the spring case 51, and the remaining part protrudes outside the spring case 51. The part protruding outside the spring case 51 supports the magnet case 55 and also the equalizer 12. The arm portion 12a is connected via a connecting pin 19.

  The compression coil spring 53 has a larger wire diameter and a larger spring constant than the compression coil spring 54, and is arranged coaxially on the outer periphery of the in-case portion of the shaft 52. The compression coil spring 53 engages with the spring case 51 at one end and engages with the flange portion 52a of the shaft 52 at the other end, and is incorporated in a state where the mounting load is substantially zero.

  The compression coil spring 54 has a smaller wire diameter and a smaller spring constant than the compression coil spring 53, and is assembled in a mounting hole 52 b provided in the shaft 52. The compression coil spring 54 is disposed coaxially with the compression coil spring 53 and is engaged with the spring case 51 via the retainer 58 at the end protruding from the attachment hole 52b. The mounting load of the compression coil spring 54 is so small that the axial clearance at both ends of the compression coil spring 53 is zero, and the shaft 52 hardly deflects the compression coil spring 53 by the compression coil spring 54. It is urged in the axial direction toward the compression coil spring 53 by a weak force.

  The magnet case 55 is assembled to the outer periphery of the case 52 in the shaft 52 by a support hole 55a, and uses one compression coil spring 71, a pair of annular sheet plates 72, 73, and a pair of clips 74, 75. The shaft 52 can be moved in the axial direction and the radial direction and can be tilted, and can move integrally with the shaft 52 in the axial direction. The support hole 55a of the magnet case 55 has a required amount larger than the outer diameter of the shaft 52, and a required amount of radial clearance (the shaft 52 is in the support hole 55a) between the shaft 52 and the support hole 55a of the magnet case 55. A gap that can be tilted by the required amount).

  The magnet case 55 includes and supports a magnet 62 that constitutes a movement amount detection means (means for detecting the relative movement amount of the Hall IC element 61 and the magnet 62) by the Hall IC element 61, as well as a guide. A guide sleeve 59 that is fitted to the pin 56 and moves the magnet case 55 in the setting direction along the guide pin 56 with respect to the spring case 51 is integrally fixed. Further, the magnet case 55 is provided with a locking portion 55 b of the tension coil spring 57.

  The guide pin 56 is fitted and fixed at one end to the mounting hole 51e of the spring case 51 and is integrally fixed to the spring case 51, and is set in the set direction (the direction in which the tension of the inner wire 15a acts). (Parallel direction). On the outer periphery of the guide pin 56, a guide sleeve 59 is slidably fitted along the axial direction of the guide pin 56 through an inner hole (guide hole) 59a.

  The tension coil spring 57 is locked at one end to a locking portion 51 c provided on the spring case 51, and is locked at the other end to a locking portion 55 b provided on the magnet case 55. The locking portion 55b is urged toward the locking portion 51c of the spring case 51 with a small load. Thereby, in a state where a part of the spring case 51 (arm part 51d) and a part of the magnet case 55 are engaged, the gap between the guide pin 56 and the guide sleeve 59 is zero, and the moving direction of the magnet case 55 is changed. The direction is along the guide pin 56.

  In this embodiment configured as described above, when the brake switch SW1 is operated, the electric motor 11 is driven to rotate in the forward direction, and the screw shaft 41 of the conversion mechanism B is rotated in the forward direction. The equalizer 12 moves in the axial direction of the screw shaft 41 from the right position (release position) in FIG. 1 toward the left position (braking position) in FIG. For this reason, the inner wires 15a and 16a of the cables 15 and 16 are pulled, and the parking brakes 13 and 14 are changed from the released state to the braked state.

  At this time (when the inner wires 15a and 16a of the cables 15 and 16 are pulled), the tension sensor TS applies an axial tensile force between the spring case 51 and the shaft 52, and the compression coil spring 53 Is compressed and deformed, a relative movement occurs between the spring case 51 and the shaft 52, the Hall IC element 61 and the magnet 62 move relatively, and the above-described tensile force is detected. This tensile force is input to the electric control unit ECU, and when the value reaches a high set value, the forward rotation drive of the electric motor 11 is stopped based on a control signal from the electric control unit ECU. When the electric motor 11 is stopped from rotating forward, the reverse rotation of the screw shaft 41 is regulated and held by the conversion mechanism B, the speed reduction mechanism A, and the like, so that the braking state of both parking brakes 13 and 14 is held.

  Further, when the release switch SW2 is operated, the electric motor 11 is driven in reverse rotation, and the screw shaft 41 of the conversion mechanism B is rotated in reverse, whereby the nut 42 and the equalizer 12 are moved to the left position (braking position) in FIG. ) To the right position (release position) in FIG. For this reason, the inner wires 15a and 16a of both the cables 15 and 16 are loosened, and both the parking brakes 13 and 14 are released from the braking state.

  At this time (when the inner wires 15a and 16a of both cables 15 and 16 are loosened), the tension sensor TS causes relative movement between the spring case 51 and the shaft 52 due to the return deformation of the compression coil spring 53. The Hall IC element 61 and the magnet 62 move relative to each other, and an axial tensile force acting between the spring case 51 and the shaft 52 is detected. This tensile force is input to the electric control unit ECU, and when the value becomes a low set value, the reverse rotation driving of the electric motor 11 is stopped based on a control signal from the electric control unit ECU.

  Incidentally, in the above-described embodiment, as shown in FIGS. 1 to 4, a predetermined amount of radial gap is provided between the shaft 52 and the mounting hole 51 a of the lower case 51 </ b> A, and the shaft 52 and the magnet case 55. A required amount of radial clearance is provided between the support holes 55a. A guide pin 56 and a guide sleeve 59 (guide means) for moving the magnet case 51 in the setting direction with respect to the spring case 51 are provided between the spring case 51 and the magnet case 55. A guide hole 59a is provided on the outer periphery of the guide pin 56 so as to be slidably fitted along the axial direction of the guide pin 56.

  For this reason, in the tension sensor TS of this embodiment, each axial end surface of the compression coil spring 53 is not formed at right angles to the axis of the compression coil spring 53, and the parallelism is poor. Even if the shaft 52 may be inclined with respect to the spring case 51 as illustrated in FIG. 5, the inclination of the shaft 52 is caused by the guide pin 56 and the guide sleeve 59 (guide means) with respect to the spring case 51. As a result, the shaft 52 is absorbed by tilting in the support hole 55a of the magnet case 55 whose movement direction is defined. For this reason, the magnet case 55 hardly tilts with respect to the spring case 51 even if the shaft 52 tilts with respect to the spring case 51 due to poor parallelism of the axial end surface of the compression coil spring 53. The unexpected relative movement that occurs between the magnet 62 provided in the magnet case 55 and the Hall IC element 61 provided in the spring case 51 can be defined as S1.

  On the other hand, as illustrated in FIG. 6, when the guide pin 56 and the guide sleeve 59 are not provided and the magnet case 55 is fitted to the shaft 52 so as not to tilt, the axial direction of the compression coil spring 53 is determined. If the shaft 52 tilts with respect to the spring case 51 due to poor parallelism of the end faces, the magnet case 55 tilts with the shaft 52 as the shaft 52 tilts. For this reason, the unexpected relative movement that occurs between the magnet 62 provided in the magnet case 55 and the Hall IC element 61 provided in the spring case 51 is S2 (S1 <S2).

  Therefore, in the tension sensor TS of this embodiment, the guide pin 56 and the guide sleeve 59 are not provided, and the magnet case 55 is fitted to the shaft 52 so as to hardly tilt (when illustrated in FIG. 6). Compared to the relative movement S2, the unexpected relative movement S1 (S1 <S2) generated between the magnet 62 provided in the magnet case 55 and the Hall IC element 61 provided in the spring case 51 can be reduced. It is possible to suppress deterioration in detection accuracy of tensile force accompanying relative movement.

  In the embodiment described above, the moving direction defining means for defining the moving direction of the magnet case 55 relative to the spring case 51 is implemented by using the guide means including the guide pin 56 and the guide sleeve 59 and the tension coil spring 57. 7 to 9, as movement direction defining means for defining the movement direction of the magnet case 55 relative to the spring case 51, guide means comprising a pair of guide pins 56, 56 and a pair of guide sleeves 59, 59. (It is also possible to implement by adopting a guide means comprising a guide pin 56 and a guide sleeve 59 on the right side of FIG. 9 instead of the tension coil spring 57).

  Further, in the above-described embodiment, a case where a flat plate is adopted as the annular sheet plate 73 on the right side of FIG. 3 and the seating surface of the annular sheet plate 73 receiving the magnet case 55 is a flat surface has been described. Instead of the plate 73, as shown in FIG. 10, an annular sheet 173 having a spherical surface centered on the axis of the shaft 52 in the mounting hole 51a of the spring case 51 is used as a seating surface for receiving the magnet case 55. It is also possible to carry out.

  In the embodiment shown in FIG. 10, the seating surface of the annular seat 173 has a spherical shape centered on the shaft center of the shaft 52 in the mounting hole 51 a of the spring case 51. Even if the shaft 52 may be inclined with respect to the spring case 51 as illustrated in FIG. 11 due to poor parallelism or the like, the inclination of the shaft 52 is caused by the guide pin 56 with respect to the spring case 51. The shaft 52 and the annular sheet 173 are absorbed in the support hole 55a of the magnet case 55 whose direction of movement is defined by the guide sleeve 59 (guide means).

  For this reason, the magnet case 55 does not move at all with respect to the spring case 51 even if the shaft 52 tilts with respect to the spring case 51 due to the poor parallelism of the axial end face of the compression coil spring 53. It is possible to do so. Therefore, the unexpected relative movement that occurs between the magnet 62 provided in the magnet case 55 and the Hall IC element 61 provided in the spring case 51 becomes zero, and the detection accuracy of the tensile force is improved as compared with the above-described embodiments. Is possible. Although the center of the seat surface of the annular seat 173 is preferably coincident with the axial center of the shaft 52 in the mounting hole 51a of the spring case 51, it is not always necessary to coincide with it and can be changed as appropriate.

  In each of the above embodiments, the Hall IC element 61 is integrally assembled to the spring case 51, and the magnet 62 is supported by the case (magnet case) assembled to the shaft 52. However, the magnet (62) is integrally assembled to the spring case (51), and the Hall IC element (61) is supported by the case (detection element case) assembled to the shaft (52). It is also possible to implement.

  In each of the above embodiments, the guide pin 56 is provided integrally with the spring case 51 and the guide sleeve 59 is provided integrally with the magnet case 55 (or the detection element case). It is also possible to carry out by providing the sleeve integrally and providing the guide pin integrally with the magnet case (or detection element case).

  In each of the above embodiments, the Hall IC element 61 and the magnet 62 are disposed outside the spring case 51. However, the Hall IC element and the magnet may be disposed within the spring case. In this case, it is necessary to set a support portion for supporting the magnet case (or the detection element case) in a portion of the shaft in the spring case.

  In each of the above embodiments, the embodiments in which the tension sensor according to the present invention is employed as the tension sensor of the electric parking brake device for a vehicle have been described. However, the tension sensor according to the present invention is employed as a tension sensor for various other devices. This is possible and is not limited to the above embodiment.

It is a partially broken top view which shows one Embodiment which employ | adopted the tension sensor by this invention as a tension sensor of the electric parking brake apparatus for vehicles. It is an enlarged plan view of the tension sensor shown in FIG. It is sectional drawing which shows the internal structure of the tension sensor shown in FIG. 1 and FIG. FIG. 4 is a cross-sectional view taken along line 4-4 of FIG. FIG. 4 is an operation explanatory diagram when the shaft tilts with respect to the spring case in the tension sensor shown in FIG. 3. In the embodiment in which the guide pin and guide sleeve of the tension sensor shown in FIG. 3 are eliminated and the magnet case is fitted to the shaft so that the magnet case hardly tilts (for comparison), the shaft tilts with respect to the spring case. FIG. It is a top view equivalent to FIG. 2 of embodiment which employ | adopted the guide pin and the guide sleeve instead of the tension | pulling coil spring of the tension sensor shown in FIG. It is sectional drawing which shows the internal structure of the tension sensor shown in FIG. FIG. 9 is a cross-sectional view taken along line 9-9 in FIG. FIG. 4 is a cross-sectional view corresponding to FIG. 3 of an embodiment in which an annular sheet having a spherical seating surface is used instead of the right annular sheet plate of the tension sensor shown in FIG. 3. FIG. 11 is an operation explanatory diagram when the shaft tilts with respect to the spring case in the tension sensor shown in FIG. 10.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Electric motor, 12 ... Equalizer, 13, 14 ... Parking brake, 15, 16 ... Cable, 21 ... Input gear, 22 ... Output gear, 23 ... Intermediate large gear, 24 ... Intermediate small gear, 31 ... Housing, 32 ... Casing, 41 ... Screw shaft, 42 ... Nut, TS ... Tension sensor, 51 ... Spring case, 51a ... Mounting hole, 52 ... Shaft, 53 ... Compression coil spring, 54 ... Compression coil spring, 55 ... Magnet case, 55a ... Support Hole 56 ... Guide pin 57 ... Tension coil spring 59 ... Guide sleeve 59a ... Guide hole 61 ... Hall IC element (detection element) 62 ... Magnet A ... Deceleration mechanism B ... Conversion mechanism ECU ... Electricity Control device

Claims (7)

A part is accommodated in the spring case (51) and the remaining part protrudes outside the spring case (51). The part is assembled in a mounting hole (51a) provided in the spring case (51) so as to be movable in the axial direction. A shaft (52) and a compression that is coaxially disposed on the outer periphery of the portion in the case of the shaft (52) and engages with the spring case (51) at one end and engages with the shaft (52) at the other end. A coil spring (53) and a magnet case that is assembled to the outer periphery of the shaft (52) by a support hole (55a) and that can move integrally with the shaft (52) in the axial direction and supports the magnet (62). (55) and a detecting element (61) which is assembled integrally with the spring case (51) and constitutes a moving amount detecting means by the magnet (62). When the axial tension force acts between the spring case (51) and the shaft (52) and the compression coil spring (53) is compressed and deformed, the magnet (62) and the detection element (61) In the tension sensor (TS) in which the tensile force can be detected by relative movement,
A predetermined amount of radial clearance is provided between the shaft (52) and the mounting hole (51a) of the spring case (51), and between the shaft (52) and the support hole (55a) of the magnet case (55). A guide means (56, 56) for providing a required amount of radial clearance and moving the magnet case (55) between the spring case (51) and the magnet case (55) in a set direction with respect to the spring case (51). 59) A tension sensor (TS) characterized by being provided.   2. The tension sensor (TS) according to claim 1, wherein the magnet case (55) is elastic in the axial direction on a seating surface of an annular sheet (173) integrally assembled on the outer periphery of the shaft (52). The tension sensor is assembled to the outer periphery of the shaft (52) in a state engaged with the shaft (52), and the seating surface is formed in a spherical shape centered on the axis of the shaft (52). (TS).   The tension sensor (TS) according to claim 1 or 2, wherein the guide means is a guide pin (56) that is integrally fixed to the spring case (51) or the magnet case (55) and extends in a setting direction. A guide hole provided in the magnet case (55) or the spring case (51) and slidably fitted on the outer periphery of the guide pin (56) along the axial direction of the guide pin (56). 59a), a tension sensor (TS). A shaft which is assembled in a mounting hole provided in the spring case so as to be movable in the axial direction, a part of which is accommodated in the spring case and the remaining part projects out of the spring case, and an outer periphery of a portion of the shaft in the case. A compression coil spring that is coaxially disposed and engages with the spring case at one end and engages with the shaft at the other end, and is assembled with a support hole on the outer periphery of the shaft so as to be integrated with the shaft in the axial direction. A detection element case that is movable and supports the detection element, and a magnet that is integrally assembled with the spring case and constitutes a moving amount detection means. The spring case and the shaft When the compression coil spring is compressively deformed due to an axial tensile force acting between the magnet and the detection element In tension sensor the pulling force can be detected with relative movement,
A predetermined amount of radial clearance is provided between the shaft and the mounting hole of the spring case, and a required amount of radial clearance is provided between the shaft and the support hole of the detection element case, and the spring case and the detection element case A tension sensor comprising a guide means for moving the detection element case in a setting direction with respect to the spring case.   5. The tension sensor according to claim 4, wherein the detection element case is elastically engaged with a seating surface of an annular sheet integrally assembled with the outer periphery of the shaft in an axial direction on the outer periphery of the shaft. The tension sensor is assembled, and the seating surface is formed in a spherical shape centered on the axis of the shaft.   7. The tension sensor according to claim 5, wherein the guide means is provided on a guide pin that is integrally fixed to the spring case or the detection element case and extends in a setting direction, and the detection element case or the spring case. And a guide hole slidably fitted along the axial direction of the guide pin on the outer periphery of the guide pin.   The electric motor (11), a conversion mechanism (B) that converts the rotational driving force of the electric motor (11) into a linear driving force, and the linear driving force that is connected to the output portion of the conversion mechanism (B) is parked. A cable (15, 16) for transmitting to the brake (13, 14) is provided, and a tension sensor (TS) capable of detecting a tensile force acting on the cable (15) and a rotational drive of the electric motor (11) are provided. An electric control device (ECU) for controlling, and the electric motor (11) is driven to rotate forward so that the cables (15, 16) are pulled to change the parking brake (13, 14) from a released state to a braking state. The cable (15, 16) is released by the reverse rotation driving of the electric motor (11), and the parking brake (13, 14) is released from the braking state. In the electric parking brake device for a vehicle configured as described above, the tension sensor (TS) according to any one of claims 1 to 6 is adopted as the tension sensor (TS). Electric parking brake device.

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