JP2015108430A - Suspension device and front fork - Google Patents

Abstract

An object of the present invention is to detect a stroke amount of a suspension device more accurately while suppressing a complicated structure of the suspension device. A front fork 30 according to the present invention includes an inner tube 311 and an outer tube 331 that are telescopically fitted, oil that is filled between the inner tube 311 and the outer tube 331, and an electrical connection to the inner tube 331. The inner tube 311 and the outer tube 331 are fitted via the first electrode 53 connected to the second electrode 55, the second electrode 55 electrically connected to the outer tube 331, and the first electrode 53 and the second electrode 55. And a control unit 51 that detects a capacitance corresponding to the fitting length. [Selection] Figure 2

Description

  The present invention relates to a suspension device and a front fork.

  Conventionally, it is known to connect a wheel of a motorcycle to a vehicle body frame via a suspension (suspension device). For example, in order to grasp the traveling state of the motorcycle, it may be required to detect a stroke amount that is an extension / contraction distance of the suspension.

  Here, Patent Document 1 discloses a suspension stroke sensor arranged in parallel with a rear shock absorber between a rear shock absorber and a reservoir tank in a rear suspension mechanism. The suspension stroke sensor includes a cylinder part and a piston part, and is attached in parallel with the sliding direction of the rear shock absorber. The piston part slides in the cylinder part in conjunction with the expansion and contraction of the rear shock absorber. As a result, the suspension stroke sensor is interlocked with the rear suspension mechanism, does not require a stroke conversion program, and can prevent scattered matters from the outside unlike the installation between the vehicle body frame and the swing arm. However, this suspension stroke sensor can only protect against flying objects from a certain direction, and has not yet reached a fundamental solution of protecting flying objects from outside in various directions. In addition, this suspension stroke sensor needs to use a suspension stroke sensor that matches the size of each rear suspension mechanism for each vehicle model with a different size of the rear suspension mechanism. It is not a suspension stroke sensor.

  Patent Document 2 discloses a suspension sensor in which an ultrasonic transmission / reception type or laser light transmission / reception type non-contact type sensor is attached to the side of the front fork. This suspension sensor can be used as a suspension sensor that is compatible with different front fork sizes that are not affected by the size of the suspension. However, it must be placed outside the front fork, so rain, wind, dirt, etc. There is a risk of being unable to measure accurately due to the influence of

  Further, Patent Document 3 discloses a stroke detection device in which pressure detection means for detecting the air pressure in the air chamber is provided in the air chamber inside the suspension by expansion and contraction of the suspension, and the stroke amount is detected from the air pressure. In this stroke detection device, the pressure detection means is downsized to detect the stroke amount at a low cost, and the pressure detection means is disposed inside the suspension to enhance the durability of the stroke detection device. However, this stroke detection device requires a stroke conversion program as a result, and if the oil amount changes due to temperature change or vehicle travel, a change in air pressure may occur, and the accuracy of the stroke detection device may not be improved. There is.

  Patent Document 4 discloses a stroke sensor for measuring the operating length of a tractor cylinder. Since this stroke sensor is disposed on the rear upper surface side of the lift cylinder, the lift cylinder can protect the scattered matter such as mud splashed up by wheels and the like. In addition, this stroke sensor is a capacitance type and can detect the stroke amount with high accuracy. However, this stroke sensor can only protect mud and the like from a certain direction, and has not yet reached a fundamental solution of protecting mud and the like from the outside in various directions. Further, for protection from mud or the like, a protective member or the like can be attached to the stroke sensor to make it firm, but in this case, the structure may be complicated and the cost may be increased. Furthermore, since the stroke sensor is arranged in parallel with the lift cylinder, it is necessary to use a stroke sensor that matches the size of the lift cylinder for each vehicle model with a different lift cylinder size. It is not a stroke sensor corresponding to the size. In Patent Document 4, a specific measurement method by which the stroke sensor measures a change in capacitance is not clear.

JP 7-208529 A JP 2010-173408 A JP 2012-240439 A Utility Model Registration No. 2514731

  By the way, even when a stroke sensor for detecting the stroke amount of the suspension device is provided, in order to reduce the manufacturing cost and improve the mass productivity, it is required to avoid the structure of the suspension device from being complicated. It is also desirable to reduce variations in the measurement accuracy of the stroke amount even when an external scattered object collides with the suspension device or when the external environment such as temperature or pressure changes.

  An object of this invention is to detect the stroke amount of a suspension apparatus more accurately, suppressing complication of the structure of a suspension apparatus.

  For this purpose, the suspension device according to the first aspect of the present invention includes an inner tube and an outer tube that are telescopically fitted, an insulator that is filled between the outer tube and the inner tube, and an electrical connection to the inner tube. The first electrode to be connected, the second electrode electrically connected to the outer tube, and the electrostatic capacity corresponding to the fitting length in which the inner tube and the outer tube are fitted via the first electrode and the second electrode. And detecting means for detecting the capacity.

  In the suspension device according to the second invention, the insulator has a constant dielectric constant.

  In the suspension device according to the third invention, the insulator is oil.

  In the suspension device according to the fourth invention, the insulator is air.

  In the suspension device according to the fifth aspect of the invention, the first electrode includes an insulating member that is provided on the inner tube side and can be attached, and a conductive member that is disposed to face the first electrode with the insulating member interposed therebetween. It is characterized by that.

  In the suspension device according to a sixth aspect of the invention, the second electrode includes an insulating member that is provided on the outer tube side and can be attached, and a conductive member that is disposed to face the second electrode with the insulating member interposed therebetween. It is characterized by that.

  A front fork according to a seventh aspect of the present invention includes an inner tube and an outer tube that are telescopically fitted, and an axle holding portion that is connected to either the inner tube or the outer tube and holds an axle of a front wheel provided in the motorcycle. An insulator filled between the outer tube and the inner tube; a first electrode electrically connected to the inner tube; a second electrode electrically connected to the outer tube; a first electrode; And detecting means for detecting a capacitance corresponding to a fitting length in which the inner tube and the outer tube are fitted via the second electrode.

  According to the first invention or the seventh invention, the first electrode electrically connected to the inner tube, the second electrode electrically connected to the outer tube, the first electrode and the second electrode, The detecting means for detecting the capacitance corresponding to the fitting length in which the inner tube and the outer tube are fitted. For this reason, the stroke amount of the suspension device (or front fork) can be detected with higher accuracy while avoiding the complexity of the configuration of the suspension device (or front fork). Furthermore, in the first invention or the seventh invention, since the electrostatic capacity corresponding to the fitting length in which the inner tube and the outer tube are fitted is detected, the influence of the external environment such as the scattered matter from outside, temperature, pressure, etc. The variation in the measurement accuracy of the stroke amount can be reduced without receiving it.

  According to the second invention, since the medium having a constant dielectric constant is filled between the inner tube and the outer tube, a proportional relationship between the change in capacitance and the fitting length is established, and the measurement accuracy of the stroke amount is established. Will improve.

  According to the third aspect of the invention, since oil is filled between the inner tube and the outer tube, friction between the inner tube and the outer tube is suppressed, and the suspension device can be easily lubricated. Moreover, the oil utilized for the original structure of a suspension apparatus can be used effectively.

  According to the fourth aspect of the invention, since the air is filled between the inner tube and the outer tube, it is not necessary to compensate for the volume of the oil that is required when filling with oil, for example.

  According to the fifth aspect, since the first electrode can be attached to the inner tube side, the first electrode can be easily attached.

  According to the sixth aspect of the invention, the second electrode can be attached to the outer tube side, so that the second electrode can be easily attached.

1 is a side view showing a schematic configuration of a motorcycle according to an embodiment. It is a longitudinal cross-sectional view of the front fork of this embodiment. (A) is a longitudinal cross-sectional view which shows the flow of the oil at the time of the compression stroke of a front fork, (b) is a longitudinal cross-sectional view which shows the flow of the oil at the time of the expansion stroke of a front fork. It is a figure for demonstrating the relative position of an inner tube and an outer tube. It is a block diagram which shows the structure of the control part of a stroke sensor. (A) is the perspective view which showed the seal electrode used for 2nd Embodiment, (b) is a longitudinal cross-sectional view of the front fork in 2nd Embodiment, (c) is the seal | sticker provided in the inner tube. It is AA 'sectional drawing shown to (a) of an electrode. (A) thru | or (d) is sectional drawing which shows the sealing electrode of another form. It is sectional drawing of the front fork in 3rd Embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a side view showing a schematic configuration of a motorcycle 1 of the present embodiment.

  <First Embodiment>

  <Motorcycle 1>

  As shown in FIG. 1, a motorcycle 1 is provided with a body frame 11 constituting a part of a vehicle body, a head pipe 12 attached to a front end portion of the body frame 11, and the head pipe 12. Two front forks 30 and a front wheel 14 attached to the lower ends of the two front forks 30 via axles 14S are provided. Two front forks 30 are arranged one on each of the left and right sides of the front wheel 14. FIG. 1 shows only the front fork 30 arranged on the right side in the traveling direction. A specific configuration of the front fork 30 will be described in detail later.

  In addition, the motorcycle 1 includes a handle 15 attached to the upper part of the front fork 30, a fuel tank 16 attached to the front upper part of the vehicle body frame 11, an engine 17 disposed below the fuel tank 16, and a speed change. Machine 18.

  The motorcycle 1 includes a seat 19 attached to the rear upper part of the body frame 11, a swing arm 20 attached to the lower part of the body frame 11 so as to be swingable, and a rear part attached to the rear end of the swing arm 20. A wheel 21 and two rear suspensions 22 attached between the swing arm 20 and the vehicle body frame 11 are provided. Two rear suspensions 22 are arranged one on each of the left and right sides of the rear wheel 21. FIG. 1 shows only the rear suspension 22 arranged on the right side in the traveling direction. Further, the motorcycle 1 includes a control device 23 that controls the entire motorcycle 1.

  The vehicle body frame 11 is a frame body that supports functional members constituting the vehicle main body such as the fuel tank 16, the engine 17, and the transmission 18. The head pipe 12 is a substantially cylindrical member. The head pipe 12 has a handle rotation shaft (not shown) provided integrally with the handle 15 and the front fork 30 inserted therein and rotatably supports the handle rotation shaft.

  The front wheel 14 is a wheel disposed on the front side in the traveling direction of the body frame 11. The handle 15 is a member that is disposed on the front side in the traveling direction of the vehicle body frame 11 and is gripped by the driver for steering the motorcycle 1. The fuel tank 16 is a container that is disposed above the vehicle body frame 11 and stores fuel therein. The engine 17 is a driving source that supplies a driving force for rotating the rear wheel 21. The transmission 18 is a transmission mechanism that transmits the driving force from the engine 17 to the rear wheel 21 while shifting the driving force.

  The seat 19 is a saddle type seat that is disposed above the vehicle body frame 11 and on which the driver rides. The swing arm 20 is a member that has a front end rotatably supported by the body frame 11 in the traveling direction and a rear end that supports the rear wheel 21 in the traveling direction. The swing arm 20 rotates around the front end in the traveling direction so as to follow the movement of the rear wheel 21. The rear wheel 21 is a wheel disposed on the rear side in the traveling direction of the body frame 11. The rear suspension 22 is a shock absorber that suppresses transmission of an impact received by the rear wheel 21 to the vehicle body frame 11 due to road surface unevenness or the like. The control device 23 includes a CPU (not shown) that performs arithmetic processing, for example, and controls the entire motorcycle 1 while receiving an output signal from a stroke sensor 50 and the like described later.

  <Configuration of front fork 30>

  FIG. 2 is a longitudinal sectional view of the front fork 30 of the present embodiment.

  The front fork 30 according to this embodiment is disposed between the body frame 11 and the front wheel 14 of the motorcycle 1 so as to be extendable and retractable, and supports the front wheel 14. The front fork 30 is a so-called inverted type in which an inner tube 311 described later is disposed on the front wheel 14 side and an outer tube 331 is disposed on the vehicle body frame 11 side.

  The front fork 30 has an inner tube 311 and is attached to the axle 14S of the front wheel 14. The front fork 30 has an outer tube 331 and a piston rod 337 and is attached to the vehicle body. A stroke sensor 50 for detecting 30 stroke amounts.

  The inner tube 311 and the outer tube 331 are substantially cylindrical members arranged coaxially. Hereinafter, the direction of the center line of the cylinder is referred to as “vertical direction”, and the body frame 11 side is referred to as “upper side”. The front wheel 14 side may be referred to as “lower side”. The front fork 30 absorbs unevenness on the road surface and suppresses vibration while supporting the axle 14 </ b> S of the front wheel 14 as the axle side unit 31 and the vehicle body side unit 33 move relatively in the vertical direction.

  First, the axle side unit 31 will be described. The axle-side unit 31 has a rod guide case 310 that guides the movement of a piston rod 337 (described later) and a substantially cylindrical shape that is open at both ends, and an inner portion to which the rod guide case 310 is attached at the upper end (upper end). An axle bracket (axle holding) that is attached to the tube 311, an oil ring 319 provided between the rod guide case 310 and the outer tube 331, and a lower end (lower end) of the inner tube 311 to support the axle 14 </ b> S. Part) 313 and an oil seal 315 provided between the lower end of the inner tube 311 and the axle bracket 313.

  The rod guide case 310 is a cylindrical member provided at the upper end portion of the inner tube 311, and the guide portion 317 whose outer peripheral surface 317 a slides on the inner peripheral surface of the outer tube 331, and guides below the guide portion 317. A bottomed cylindrical member formed continuously with the portion 317 and having an outer diameter smaller than that of the guide portion 317, a cylindrical portion 318 disposed inside the inner tube 311, and a bottom portion of the cylindrical portion 318. An oil supply / discharge section 321 that enables oil to be supplied / discharged between an oil reservoir chamber 41 and a hydraulic oil chamber 43, which will be described later, is provided.

  The guide part 317 is formed from a metal, for example. On the outer peripheral surface 317a of the guide portion 317, a ring groove 317b into which a convex portion 319a (described later) of an oil ring 319 that seals between the inner peripheral surface of the outer tube 331 and the rod guide case 310 is fitted is provided in the entire region in the circumferential direction. It is formed across. In addition, the lower end surface 317c of the guide portion 317 functions as an abutting surface against which the upper end surface 311d of the inner tube 311 abuts. That is, the lower end surface 317c of the guide portion 317 is formed on a surface orthogonal to the up-down direction, contacts the upper end surface 311d of the inner tube 311 over the entire circumference, and the piston rod side oil chamber 431 (described later). Seal the upper part.

  Further, the guide portion 317 guides the outer tube 331 while the outer peripheral surface 317 a is abutted against the inner peripheral surface of the outer tube 331 via the oil ring 319. More specifically, the guide portion 317 keeps the distance between the inner tube 311 and the outer tube 331 constant.

  The cylindrical portion 318 is made of, for example, metal, and is formed so that the direction of the center line is the vertical direction. The cylindrical portion 318 includes an inward portion 318a that is provided at the lower end portion and is formed so as to be directed inward in the radial direction so as to close the opening of the lower end portion. Further, a male screw 318 b that is fastened to a female screw 311 a formed in the inner tube 311 is formed on the outer peripheral surface of the upper end portion of the cylindrical portion 318.

  The supply / discharge part 321 is connected to the first oil path 321a and the first oil path 321a and the second oil path 321b communicating with the oil storage part 412 of the oil reservoir chamber 41 and the piston rod side oil chamber 431 of the hydraulic oil chamber 43. Provided in the second oil passage 321b and a check valve 321c that is provided and that allows oil flow from the oil reservoir 412 to the hydraulic oil chamber 43 and blocks oil flow from the hydraulic oil chamber 43 to the oil reservoir 412. And a throttle 321d for restricting the flow of oil.

  In the rod guide case 310 configured as described above, the inward portion 318a partitions the space in the inner tube 311 into a space above the inward portion 318a and a space below the inward portion 318a. . Here, the space above the inward portion 318a constitutes a part of the oil reservoir chamber 41 in which oil is accumulated, and the space below the inward portion 318a is a hydraulic oil chamber 43 in which oil is accumulated.

  In addition, the lower space in the oil reservoir 41 and a portion in which oil is accommodated serve as an oil accommodating portion 412, and the upper space in the oil reservoir 41 and in which air is accommodated is an air accommodating portion 414. Become. The air accommodating portion 414 functions as an air spring that absorbs the impact force transmitted to the front fork 30.

  The inner tube 311 is formed of a conductive material such as aluminum or iron. The outer diameter of the inner tube 311 is formed smaller than the inner diameter of the outer tube 331. A predetermined amount of oil is injected into the inner tube 311. This oil is an electrical insulating oil and avoids electrical connection between the inner tube 311 and the outer tube 331.

  Further, when the inner tube 311 enters the outer tube 331, an annular oil chamber (annular space) that is an annular oil chamber (space) is formed between the outer peripheral surface of the inner tube 311 and the inner peripheral surface of the outer tube 331. ) 39 is formed. The annular oil chamber 39 is filled with oil.

  The inner peripheral surface of the inner tube 311 is formed with a uniform inner diameter along the vertical direction so that a piston 335 described later of the vehicle body side unit 33 slides smoothly. However, an internal thread 311a is formed on the inner peripheral surface of the upper end. On the other hand, the outer peripheral surface of the inner tube 311 is basically formed with a uniform outer diameter along the vertical direction. A male screw 311b is formed on the outer peripheral surface of the lower end portion of the inner tube 311. In addition, in the state where the rod guide case 310 is attached to the inner tube 311, a communication hole 323 that communicates the inside of the inner tube 311 and the annular oil chamber 39 is formed at a lower portion than the rod guide case 310. Is formed.

  The oil ring 319 is an annular member formed of an insulating material such as a resin. In addition, the oil ring 319 includes a convex portion 319 a that protrudes from the inner peripheral surface of the oil ring 319 toward the inside in the radial direction.

  The oil ring 319 is attached to the guide portion 317 by fitting the convex portion 319a into the ring groove 317b of the guide portion 317. The oil ring 319 attached to the guide portion 317 is sandwiched between the outer peripheral surface 317a of the guide portion 317 and the inner peripheral surface of the outer tube 331. The oil ring 319 is an example of an insulator and avoids electrical connection between the inner tube 311 and the outer tube 331.

  The axle bracket 313 is made of a conductive material such as aluminum or iron. The axle bracket 313 is formed with a recess 313a into which the inner tube 311 is inserted and an axle attachment hole 313b to which the axle 14S of the front wheel 14 can be attached.

  In the recess 313a, a female screw 313c to which the male screw 311b of the inner tube 311 is fastened, a seal groove 313d into which the oil seal 315 is fitted, and a bottom portion 313e that covers the opening of the lower end portion of the inner tube 311 are formed. .

  The axle mounting hole 313b is formed as a through-hole penetrating the substantially central portion of the axle bracket 313.

  The axle bracket 313 is attached so as to close the opening of the lower end portion of the inner tube 311 by fastening the male screw 311b of the inner tube 311 to the female screw 313c. At this time, the axle bracket 313 and the inner tube 311 are electrically connected.

  The oil seal 315 is a substantially annular member formed from an insulating material such as resin. The oil seal 315 is fitted in and attached to the seal groove 313d, seals between the outer peripheral surface of the inner tube 311 and the axle bracket 313, and prevents leakage of oil injected into the inner tube 311.

  Next, the vehicle body side unit 33 will be described. The vehicle body side unit 33 includes a substantially cylindrical outer tube 331 having both ends opened, and a guide bush 332 and an oil seal 333 attached to a lower end (lower end) of the outer tube 331. In addition, the vehicle body side unit 33 includes a piston 335 that divides the hydraulic oil chamber 43 formed in the space inside the inner tube 311 into two parts, and is fixed to the piston 335 and on the vehicle body frame 11 (see FIG. 1) side. An extended piston rod 337 and a cap 339 attached to the upper end (upper end) of the outer tube 331 and closing the upper opening are provided.

  The outer tube 331 is a substantially cylindrical member formed of a conductive material such as aluminum or iron, but the outer tube 331 has a guide bush 332 and an oil seal 333 inside on the lower end. The diameter is expanded so that it can be held. The outer tube 331 has a female thread 331a formed on the inner peripheral surface of the upper end.

  The guide bush 332 is a member for smooth sliding between the inner peripheral surface of the outer tube 331 and the outer peripheral surface of the inner tube 311. The guide bush 332 is a cylindrical bearing made of an insulating material such as resin, and the inner peripheral surface of the guide bush 332 is located on the inner side of the inner peripheral surface of the outer tube 331 when attached to the outer tube 331. The inner diameter of the guide bush 332 is set smaller than the inner diameter of the outer tube 331 so as to protrude.

  The oil seal 333 is a member formed of an insulating material such as rubber, for example, and prevents the oil leaking from the guide bush 332 from flowing out to the outside as the outer tube 331 and the inner tube 311 slide.

  Here, the guide bush 332 and the oil seal 333 are formed of an insulating material as described above, and avoid electrical connection between the inner tube 311 and the outer tube 331. The guide bush 332 keeps the distance between the inner tube 311 and the outer tube 331 constant.

  Piston 335 is a cylindrical member having a plurality of oil passages. On the outer peripheral surface of the piston 335, a ring groove 335h into which an oil ring 341 for sealing between the inner peripheral surface of the inner tube 311 is fitted is formed. The oil ring 341 fitted in the ring groove 335h has the hydraulic oil chamber 43 positioned above the oil ring 341 and the piston rod side oil chamber 431 in which the piston rod 337 exists, and the oil ring 341. The oil flow with the piston-side oil chamber 433, which is an oil chamber located on the lower side, is sealed.

  Further, the piston 335 includes a third oil passage 335 a and a fourth oil passage 335 b that communicate the piston rod side oil chamber 431 and the piston side oil chamber 433. The piston 335 is provided in the third oil passage 335a, and allows the oil to flow from the piston rod side oil chamber 431 to the piston side oil chamber 433, and from the piston side oil chamber 433 to the piston rod side oil chamber 431. A check valve 335d for blocking the flow of oil and a throttle valve 335e for limiting the flow of oil are provided. Further, the piston 335 is provided in the fourth oil passage 335b, and restricts the oil flow. The piston 335 allows the oil to flow from the piston-side oil chamber 433 to the piston-rod-side oil chamber 431, and on the piston-rod side. And a check valve 335g for blocking the flow of oil from the oil chamber 431 to the piston-side oil chamber 433.

  The piston rod 337 is a cylindrical member, and a male screw 337a is formed on the outer peripheral surface of the upper end portion.

  The cap 339 is a disk-shaped member made of an insulating material such as a resin, for example, and a male screw 339a fastened to a female screw 331a formed on the inner peripheral surface of the outer tube 331 is formed on the outer peripheral surface. The cap 339 seals the outer tube 331 by tightening the male screw 339a to the female screw 331a of the outer tube 331.

  The cap 339 has a recess 339c into which the piston rod 337 is inserted. A female screw 339b to which a male screw 337a formed on the piston rod 337 is fastened is formed on the inner peripheral surface of the recess 339c. The cap 339 holds the piston rod 337 by tightening the male screw 337a formed on the piston rod 337 to the female screw 339b. Since the cap 339 is formed of an insulating material as described above, electrical connection between the inner tube 311 and the outer tube 331 via the piston rod 337 and the piston 335 is avoided.

  <Operation of front fork 30>

  Next, the operation of the front fork 30 configured as described above will be described. 3A is a longitudinal sectional view showing the flow of oil during the compression stroke of the front fork 30, and FIG. 3B is a longitudinal sectional view showing the flow of oil during the extension stroke of the front fork 30.

  First, the operation of the front fork 30 during the compression stroke will be described with reference to FIG. When the axle side unit 31 moves upward with respect to the vehicle body side unit 33 as indicated by a white arrow, the position of the piston 335 in the inner tube 311 moves downward, and the pressure in the piston side oil chamber 433 increases. . The oil in the piston-side oil chamber 433 flows into the piston rod-side oil chamber 431 via the fourth oil passage 335b (see arrow A1). The oil flow from the piston side oil chamber 433 to the piston rod side oil chamber 431 is throttled by the throttle valve 335f to obtain a damping force during the compression stroke of the front fork 30.

  Further, when the axle unit 31 moves upward, the volume of the annular oil chamber 39 increases, and the pressure in the annular oil chamber 39 becomes negative due to a shortage of oil corresponding to the increased volume. Accordingly, the oil in the piston rod side oil chamber 431 flows into the annular oil chamber 39 through the communication hole 323 (see arrow A2).

  The shortage of oil supplied from the piston rod side oil chamber 431 to the annular oil chamber 39 is transferred from the oil storage portion 412 of the oil reservoir chamber 41 to the piston rod side oil chamber 431 via the first oil passage 321a. (See arrow A3).

  Next, the behavior of the front fork 30 during the extension stroke will be described with reference to FIG. When the axle side unit 31 moves downward relative to the vehicle body side unit 33 as indicated by the white arrow, the position of the piston 335 in the inner tube 311 moves upward, and the pressure in the piston side oil chamber 433 is negative. Pressure. As a result, the oil in the piston rod side oil chamber 431 flows into the piston side oil chamber 433 through the third oil passage 335a (see arrow B1). The oil flow from the piston rod side oil chamber 431 to the piston side oil chamber 433 is throttled by the throttle valve 335e to obtain a damping force during the extension stroke of the front fork 30.

  Further, when the axle unit 31 moves downward, the volume of the annular oil chamber 39 decreases, and the pressure in the annular oil chamber 39 increases due to excess oil corresponding to the reduced volume. As a result, the oil in the annular oil chamber 39 flows into the piston rod side oil chamber 431 through the communication hole 323 (see arrow B2).

  The excess amount of oil supplied from the annular oil chamber 39 to the piston rod side oil chamber 431 is transferred from the piston rod side oil chamber 431 to the oil storage portion 412 of the oil reservoir chamber 41 via the second oil passage 321b. (See arrow B3). The flow of oil from the piston rod side oil chamber 431 to the oil storage portion 412 is throttled by the throttle 321d, and a damping force is obtained during the extension stroke of the front fork 30.

  The front fork 30 configured as described above absorbs an impact force during traveling of the motorcycle 1 to which the front fork 30 is attached while extending and contracting. Note that the annular oil chamber 39 in the illustrated example is maintained in a state of being filled with oil regardless of the expansion / contraction state of the front fork 30.

  <Change in capacitance of front fork 30>

  FIG. 4 is a view for explaining the relative positions of the inner tube 311 and the outer tube 331. In FIG. 4, members other than the inner tube 311 and the outer tube 331 are omitted and a part of the shape is simplified for clarity.

  Now, in the front fork 30 according to the present embodiment, as described with reference to FIG. 2, for example, the outer tube 331 and the inner tube 311 which are cylindrical members each formed of a conductive material are coaxial. It has a so-called double pipe structure. Further, the inner tube 311 and the outer tube 331 are insulated. Therefore, the inner tube 311 and the outer tube 331 can be regarded as a coaxial cylindrical capacitor.

  Here, when the stroke amount of the front fork 30 changes, the inner tube 311 and the outer tube 331 move relatively in the vertical direction (axial direction), and the fitting length L changes. And according to this fitting length L, the capacitance C of the inner tube 311 and the outer tube 331 that function as a coaxial cylindrical capacitor changes. More specifically, the capacitance C corresponding to the fitting length L, which is the length of the portion where the inner tube 311 and the outer tube 331 are fitted, changes. Below, the relationship between this electrostatic capacitance C and fitting length L is demonstrated.

  The stroke amount is an amount in which the relative position of the axle side unit 31 with respect to the vehicle body side unit 33 is changed from a predetermined reference position (for example, refer to the position of the axle side unit 31 shown in FIG. 3A) in the vertical direction. (See symbol S in FIG. 3). In addition, the fitting length L refers to a distance between regions in which the inner tube 311 and the outer tube 331 overlap (regions to be fitted) in the vertical direction. In addition, the fitting length L in the illustrated example is a distance from the upper end surface 311 d of the inner tube 311 to the lower end surface 331 b of the outer tube 331. Further, in the present embodiment, the change amount ΔL of the fitting length L matches the change amount of the stroke of the front fork 30.

  As shown in FIG. 4, the radius to the inner peripheral surface of the outer tube 331 is R, the distance to the outer peripheral surface of the inner tube 311 is r, and the outer peripheral surface of the inner tube 311 and the inner peripheral surface of the outer tube 331 are If the dielectric constant between is ε, the relationship between the capacitance C and the fitting length L is expressed by the following equation (1).

  C = 2πεL / log (R / r) (1)

  That is, since the radius R, the distance r, and the dielectric constant ε are constants in the individual front forks 30, the capacitance C is proportional to the fitting length L. Further explanation will be made with reference to FIGS. 3A and 3B. In the state shown in FIG. 3A, the fitting length L1 is shown, and in the state shown in FIG. 3B, the fitting length L2 is shown. (> Fitting length L1). For this reason, in the state shown in FIG. 3B, the capacitance C of the inner tube 311 and the outer tube 331 is larger than that in the state shown in FIG. In addition, regarding the fitting length L1 and the fitting length L2, in FIG. 3, the length from the lower end of the guide part 317 to the lower end of the oil seal 333 is shown. However, the present invention is not limited to this, and the capacitance C varies depending on the shape of the outer tube 331 and the sealing properties of the guide portion 317, the guide bush 332, and the oil seal 333. The total length L is corrected and adjusted.

  <Stroke sensor 50>

  FIG. 5 is a block diagram illustrating a configuration of the control unit 51 of the stroke sensor 50.

  A stroke sensor 50, which is an example of a suspension device stroke sensor, detects changes in the capacitance C of the inner tube 311 and the outer tube 331. Based on the change amount ΔC of the capacitance C, the change amount ΔL of the fitting length L, that is, the stroke amount of the front fork 30 is detected.

  As shown in FIG. 5, the stroke sensor 50 includes a control unit 51 that controls the stroke sensor 50, and a first power supply cable 52 that has one end connected to the control unit 51 and transmits power from the control unit 51. A first electrode 53 connected to the other end of the first power supply cable 52; a second power supply cable 54 having one end connected to the control unit 51 and transmitting power from the control unit 51; And a second electrode 55 connected to the other end of the power supply cable. Hereinafter, the first electrode 53 and the second electrode 55 may be referred to as an electrode 57.

  The control unit 51 includes a CPU that performs calculation processing for calculating a stroke amount, a ROM that stores programs executed by the CPU, various data, and the like, a RAM that is used as a work memory of the CPU, an EEPROM (Electrically Erasable & Programmable Read Only Memory).

  The control unit 51, which is an example of a detection unit, includes a power supply unit 511 that supplies power from a power source (not illustrated) to the first electrode 53 and the second electrode 55, and the outer tube 331 and the inner tube via the power supply unit 511. 311, a detection unit 513 that detects the capacitance C (information on capacitance), and a storage unit 517 that stores a table (not shown) that defines the relationship between the change amount ΔC of the capacitance C and the stroke amount. And an output unit 515 that outputs the stroke amount of the front fork 30 based on the capacitance C detected by the detection unit 513 and the table stored in the storage unit 517.

  Here, specific configurations of the first electrode 53 and the second electrode 55 will be described with reference to FIG. The first electrode 53 is electrically connected to the inner tube 311 of the axle side unit 31. The first electrode 53 in the illustrated example is provided on the outer peripheral surface of the axle bracket 313. The second electrode 55 is electrically connected to the outer tube 331 of the vehicle body side unit 33. The second electrode 55 in the illustrated example is provided on the outer peripheral surface of the upper end portion of the outer tube 331. Accordingly, the first electrode 53 and the second electrode 55 are respectively provided at both ends of the front fork 30 in the vertical direction. The first electrode 53 and the second electrode 55 are fixed to the outer peripheral surface of the axle bracket 313 or the outer tube 331 by a known method such as soldering or welding.

  Next, the operation of the stroke sensor 50 configured as described above will be described with reference to FIGS. 2 and 5. When the stroke sensor 50 measures the stroke amount, first, the power supply unit 511 applies a predetermined voltage to the outer tube 331 and the inner tube 311 via the first electrode 53 and the second electrode 55. As a result, electric charges are stored between the outer tube 331 and the inner tube 311. Then, the detection unit 513 detects the capacitance C of the outer tube 331 and the inner tube 311. And the detection part 513 can detect variation | change_quantity (DELTA) C of the electrostatic capacitance C, for example by repeating a measurement with a predetermined period. The detecting unit 513 detects a change amount ΔC of the capacitance C by detecting a change in impedance with respect to an alternating current of the outer tube 331 and the inner tube 311 and a change in frequency of the LC transmission circuit or the RC transmission circuit. It implement | achieves by well-known means.

  The output unit 515 outputs the stroke amount of the front fork 30 based on the detected change amount ΔC of the capacitance C and the table stored in the storage unit 517. To describe further, for example, the output unit 515 converts the output stroke amount into a digital signal and transmits it to the control device 23 connected to the output unit 515 via a cable (not shown). Note that this stroke amount is important data for realizing a so-called control suspension corresponding to a high-speed change in the damping force obtained in the front fork 30 and the reaction force received by the front fork 30. By this control based on the stroke amount, it is possible to obtain riding comfort and stability that cannot be realized in a suspension without control.

  Here, in the stroke sensor 50 according to the present embodiment, the oil ring 319 and the oil seal 333 are disposed in the vertical direction between the outer peripheral surface of the inner tube 311 and the inner peripheral surface of the outer tube 331, that is, in the annular oil chamber 39. It is sealed at two points and is filled with oil regardless of the expansion / contraction state of the front fork 30. More specifically, in the annular oil chamber 39, other insulating media such as air are not accommodated in addition to oil. Therefore, the dielectric constant ε in the annular oil chamber 39 coincides with the dielectric constant ε of oil and is constant regardless of the expansion / contraction state of the front fork 30. As a result, the proportional relationship between the capacitance C and the fitting length L represented by the above formula (1) is more stable, and the stroke amount measurement accuracy is further increased. In other words, the oil in the annular oil chamber 39 also functions as lubricating oil for sliding between the inner tube 311 and the outer tube 331.

  Further, in the stroke sensor 50 according to the present embodiment, the stroke amount is calculated based on the region located inside the front fork 30, that is, the region where the outer peripheral surface of the inner tube 311 and the inner peripheral surface of the outer tube 331 face each other. taking measurement. Therefore, compared with the case where the stroke amount is measured at a portion exposed to the outside of the front fork 30, in addition to the durability of the stroke sensor 50, the scattered matter from outside such as mud, dust, water, or wind The influence of the external environment such as temperature and pressure is suppressed, and the measurement accuracy of the stroke amount is further increased. In addition, the stroke sensor 50 according to the present embodiment is a capacitance type and is not affected by temperature, pressure, dust, or the like.

  The stroke sensor 50 according to this embodiment measures the stroke amount by electrically connecting the first electrode 53 and the second electrode 55 to the outer tube 331 and the inner tube 311 in the front fork 30. It becomes possible. That is, by providing the stroke sensor 50 according to the present embodiment, the front fork 30 itself is used as a sensor.

  In addition, the stroke sensor 50 can be installed on the front fork 30 without the need for providing a special addition to the front fork 30. Further, when the stroke sensor 50 is mass-produced, it is not necessary to change the size of the stroke sensor 50 even if the motorcycle 1 to which the stroke sensor 50 is applied has a different size. That is, the stroke sensor 50 has high mass productivity, and the manufacturing cost is also reduced.

  In addition, when the stroke sensor 50 is installed, since it is a so-called general-purpose size that is not limited by the shape and size of the front fork 30, for example, the stroke sensor 50 is attached to the front fork 30 provided in the motorcycle 1 already sold. It can be installed by so-called retrofitting.

  Further, in the stroke sensor 50 according to the present embodiment, the shape and material of the first electrode 53 and the second electrode 55 have a high degree of design freedom, and in accordance with various conditions such as the vehicle type and usage status of the motorcycle 1, The first electrode 53 and the second electrode 55 can be designed.

  Furthermore, in the stroke sensor 50 according to the present embodiment, since the first electrode 53 and the second electrode 55 have no movable part, the durability is high as compared with the configuration including the movable part.

  Second Embodiment

  Next, a second embodiment will be described. FIG. 6A is a perspective view showing the seal electrode 60 used in the second embodiment, and FIG. 6B is a longitudinal sectional view of the front fork 300 in the second embodiment, and FIG. FIG. 6 is a cross-sectional view taken along line AA ′ of (a) of the seal electrode 60 provided on the inner tube 311.

  Although it has been described that the electrode 57 as an example of the terminal is directly fixed to the axle bracket 313 and the outer tube 331 by soldering, welding, or the like, the fixing method of the electrode 57 is not limited to this. For example, as shown in FIG. 6A, fixing may be performed by so-called pasting while using a seal electrode 60 as the electrode 57. The seal electrode 60 includes a base film 61 made of an insulating resin film, an insulating adhesive layer 62 made of an adhesive applied to one surface 61 a of the base film 61, and a base film 61 A thin film (metal foil) made of metal such as aluminum and laminated on the other surface 61b, and is electrically connected to the metal layer 63 and one end of the metal layer 63 which is a sheet-like conductive member. A power feeding cable 65 whose other end is connected to the control unit 51, and a laminate film 67 that is a protective layer that is formed of resin or the like and covers one surface 61a of the base film 61, the metal layer 63, and one end of the power feeding cable 65. Prepare.

  For example, like the front fork 300 shown in FIG. 6B, the seal electrode 60 may be used as the first electrode 531 and the second electrode 551 of the stroke sensor 500.

  In the first electrode 531, the adhesive layer 62 is attached to the outer peripheral surface of the inner tube 311 and a portion that does not enter the outer tube 331 (non-sliding portion). As a result, the base film 61 and the adhesive layer 62 that are insulating members are sandwiched between the metal layer 63 and the inner tube 311. And if electric power is supplied from the control part 51 via the electric power feeding cable 65, an electric charge will be stored between the metal layer 63 and the inner tube 311 (refer FIG.6 (c)).

  On the other hand, in the second electrode 551, the adhesive layer 62 is attached to the outer peripheral surface of the outer tube 331. As a result, the base film 61 and the adhesive layer 62 that are insulators are sandwiched between the metal layer 63 and the outer tube 331. When electric power is supplied from the control unit 51 via the power supply cable 65, electric charges are stored between the metal layer 63 and the outer tube 331.

  Here, the metal layer 63 and the inner tube 311 can be regarded as a first capacitor, and the metal layer 63 and the outer tube 331 can be regarded as a second capacitor. The inner tube 311 and the outer tube 331 provided with the first electrode 531 and the second electrode 551 are a first capacitor, a coaxial cylindrical capacitor of the inner tube 311 and the outer tube 331, and a second capacitor in series. It can be understood as a state of being arranged. In other words, the first capacitor, the coaxial cylindrical capacitor of the inner tube 311 and the outer tube 331, and the second capacitor are capacitively coupled. Accordingly, the detected capacitance Cd detected by the stroke sensor 50 is expressed by the following equation.

  1 / Cd = 1 / C + 1 / C1 + 1 / C2 (2)

  Here, C is the capacitance of the inner tube 311 and the outer tube 331, C1 is the capacitance of the first capacitor, and C2 is the capacitance of the second capacitor.

  The capacitance C1 of the first capacitor is calculated based on the dimension (fixed value) of the metal layer 63 in the first electrode 531, and the capacitance C2 of the second capacitor is calculated from the metal layer 63 in the second electrode 551. Calculated based on dimensions (fixed values). Therefore, in this embodiment, based on the detected capacitance Cd detected by the stroke sensor 50, the capacitance C1 of the first capacitor, and the capacitance C2 of the second capacitor, the inner tube 311 and the outer tube 331 Capacitance C is required.

  Here, by using the seal electrode 60 as the first electrode 531 and the second electrode 551, it is possible to fix by sticking, and attachment work becomes easier compared to the case of fixing by welding or the like. Moreover, the structure for attachment becomes simple and the degree of freedom of the attachment position increases. More specifically, the attachment positions of the first electrode 531 and the second electrode 551 can be easily changed.

  FIGS. 7A to 7D are cross-sectional views showing seal electrodes 601 to 607 of other forms. 7A to 7D are sectional views of seal electrodes 601 to 607 provided on the inner tube 311 as in FIG. 6C.

  In the above description, the seal electrode 60 has been described with the adhesive layer 62 applied to the one surface 61 a of the base film 61. However, any material can be used as long as it can be fixed by pasting the seal electrode 60.

  For example, a seal electrode 601 shown in FIG. 7A includes a metal layer 631 and an adhesive layer 621 made of an insulating adhesive applied to one surface of the metal layer 631. May be.

  Alternatively, an adhesive layer 623 formed by applying an insulating adhesive to the inner tube 311 and a metal layer 633 provided on the adhesive layer 623 as in the seal electrode 603 shown in FIG. The structure provided may be sufficient.

  Alternatively, like a seal electrode 605 shown in FIG. 7C, a base film 615 made of an insulating resin film, and a metal layer 635 arranged so as to sandwich the base film 615 with the inner tube 311; The base film 615 and the metal layer 635 may be provided so as to cover the laminate film 675 provided with an adhesive around the base film 615 and the metal layer 635.

  Alternatively, as shown in a seal electrode 607 shown in FIG. 7D, a base film 617 made of an insulating resin film and an insulating adhesive applied to one surface of the base film 617 are used. An adhesive layer 627, a metal layer 637 laminated on the other surface of the base film 617, a laminate film 677 provided so as to cover the base film 617 and the metal layer 637, and an adhesive applied around May be provided.

  Here, it has been described that the seal electrodes 601 to 607 are fixed to the inner tube 311, but the seal electrodes 601 to 607 may be fixed to the outer tube 331.

  In the above description, it has been described that both the first electrode 531 and the second electrode 551 are configured by the seal electrode 60, but only one of the first electrode 531 and the second electrode 551 is the seal electrode 60. Of course, you may comprise.

  In other words, the seal electrode 60 can be attached to the inner tube 311 (or outer tube 331), and the inner tube 311 (or outer tube 331) and the metal layer 63 are sandwiched between the adhesive layer 62 and the like. It is not essential that the metal layer 63 has a sheet shape as long as the metal layer 63 is insulated. For example, the metal layer 63 may be configured in other shapes such as a rectangular parallelepiped or a cylindrical shape.

  Here, it has been described that the seal electrode 60 is directly attached to the inner tube 311 or the outer tube 331. However, the seal electrode 60 and the inner tube 311 or the outer tube 331 are electrically connected to each other via other members. You may connect. For example, the seal electrode 60 and the inner tube 311 may be electrically connected via the axle bracket 313 by attaching the seal electrode 60 to the axle bracket 313.

  <Third Embodiment>

  FIG. 8 is a cross-sectional view of the front fork 400 in the third embodiment.

  In the above description, by forming the communication hole 323 communicating with the inner side of the inner tube 311, the state in which the annular oil chamber 39 is filled with oil is maintained while oil flows through the communication hole 323. Explained. However, as long as the inner tube 311 and the outer tube 331 are insulated, other modes may be used.

  For example, the structure which does not provide the communicating hole 323 like the front fork 400 shown in FIG. More specifically, the inner side of the inner tube 411 and the annular oil chamber 39 are not communicated, and the inside of the annular oil chamber 39 is filled with air.

  In this configuration, by providing the oil ring 319, it is possible to suppress oil from entering the annular oil chamber 39 from the inner tube 411 through the air accommodating portion 414. Therefore, the state where the annular oil chamber 39 is filled with air is maintained, and the measurement accuracy of the stroke amount is further increased. Further, since the oil seal 333 is provided, it is possible to prevent scattered matters such as mud, dust, and water from entering the annular oil chamber 39 from the outside. In this embodiment, the oil seal 333 may be omitted and the structure may be simplified. Further, in this embodiment, since so-called oil volume compensation is not required, work such as maintenance is suppressed.

  In addition, although filling the inside of the annular oil chamber 39 with oil has been described, it may of course be another liquid having insulation properties, for example, pure water such as deionized water.

  Of course, the annular oil chamber 39 may be filled with air and oil. In this case, it is preferable that the mixing ratio of air and oil is maintained even when the stroke amount of the front fork 30 changes. As a result, the dielectric constant ε in the annular oil chamber 39 becomes constant.

  In the above description, although not described, the rod guide case 310 and the oil ring 319 function as bearings that support the inner tube 311 and the outer tube 331. The rod guide case 310 and the oil ring 319 support the inner tube 311 and the outer tube 331 while insulating them, and seal the upper portion of the annular oil chamber 39.

  The guide bush 332 and the oil seal 333 constitute a second bearing portion 330 that supports the inner tube 311 and the outer tube 331. The second bearing portion 330 supports the inner tube 311 and the outer tube 331 while insulating them, and seals the lower portion of the annular oil chamber 39.

  In the above description, the configuration in which the stroke sensor 50 is provided on the inverted front fork 30 has been described. However, if the relative positions of the inner tube 311 and the outer tube 331 are changed as described above, the upright front fork 30 is upright. Of course, it may be an expression. Alternatively, the present invention may be applied to a suspension device of another mode used for the motorcycle 1 such as the rear suspension 22 (see FIG. 1), or a suspension device used for a vehicle such as a four-wheel vehicle other than the motorcycle 1 such as a normal automobile. .

  In the above description, the structure in which oil is injected into the inner tube 311 has been described. However, if the relative position of the inner tube 311 and the outer tube 331 is a so-called double tube structure, The stroke sensor 50 can be applied. For example, the present invention is not limited to a configuration in which oil is injected into the inner tube 311, and the stroke sensor 50 is applied when the inner tube 311 is filled with only air, not oil, and this air is used as an air spring. Of course.

  In the above description, it has been described that the rod guide case 310 and the guide bush 332 or the cap 339 functioning as bearings for the inner tube 311 and the outer tube 331 are formed from an insulating material such as a resin. 311 and the outer tube 331 are insulated from each other, these members are made of, for example, a material obtained by processing a surface of Teflon (registered trademark) with a metal as a base material, or a metal with a resin as a base material. These members (for example, bearings) may be arranged.

  Alternatively, as long as the inner tube 311 and the outer tube 331 are insulated from each other, the inner tube 311 and the outer tube 331 may be configured to provide an insulating layer on the surface of a metal base material. For example, the structure which performs an alumite process on the surface using aluminum as a base material, and forms an insulating oxide film may be sufficient.

  In the above description, the axle bracket 313 is formed of a conductive material. However, if the first electrode 53 and the inner tube 311 are electrically connected, for example, alumite treatment is performed. It may be configured to ensure electrical connection by further masking the applied surface with a conductive material.

  In the above description, it has been described that the control unit 51 outputs the stroke amount while referring to a table (not shown) that defines the relationship between the change amount ΔC of the capacitance C and the stroke amount. Of course, the controller 51 may calculate the stroke amount from the detected capacitance C by a program.

  In the above description, the control unit 51 and the control device 23 are provided as separate bodies, and the control device 23 receives a signal related to the stroke amount output from the control unit 51. However, for example, as a configuration in which the control unit 51 is not provided, the first electrode 53 and the second electrode 55 are directly connected to the control device 23 via the first power supply cable 52 and the second power supply cable 54, respectively. A configuration in which 23 also serves as the function of the control unit 51 described above, that is, a configuration in which the control device 23 outputs a stroke amount may be employed.

DESCRIPTION OF SYMBOLS 1 ... Motorcycle, 30 ... Front fork, 39 ... Annular oil chamber, 50 ... Stroke sensor, 51 ... Control part, 53 ... 1st electrode, 55 ... 2nd electrode, 311 ... Inner tube, 313 ... Axle bracket, 331 ... Outer tube

Claims (7)

An inner tube and an outer tube fitted in a telescopic manner;
An insulator filled between the outer tube and the inner tube;
A first electrode electrically connected to the inner tube;
A second electrode electrically connected to the outer tube;
A suspension device comprising: a detecting unit that detects a capacitance corresponding to a fitting length in which the inner tube and the outer tube are fitted through the first electrode and the second electrode. The suspension device according to claim 1, wherein the insulator has a constant dielectric constant. The suspension apparatus according to claim 2, wherein the insulator is oil. The suspension apparatus according to claim 2, wherein the insulator is air. The first electrode includes an insulating member that is provided on the inner tube side and can be attached, and a conductive member that is disposed to face the first electrode with the insulating member interposed therebetween. The suspension device according to any one of claims 1 to 4. The second electrode includes an insulating member that is provided on the outer tube side and can be attached, and a conductive member that is disposed to face the second electrode with the insulating member interposed therebetween. The suspension device according to any one of claims 1 to 5. An inner tube and an outer tube fitted in a telescopic manner;
An axle holding part that is connected to one of the inner tube and the outer tube and holds an axle of a front wheel provided in the motorcycle;
An insulator filled between the outer tube and the inner tube;
A first electrode electrically connected to the inner tube;
A second electrode electrically connected to the outer tube;
A front fork comprising: a detecting unit configured to detect a capacitance corresponding to a fitting length in which the inner tube and the outer tube are fitted through the first electrode and the second electrode.

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