JP2015113966A - Suspension - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a suspension which can reduce the size of a stroke sensor even if a stroke of a damper is detected by using the stroke sensor.SOLUTION: A suspension having a stroke detection device 3A which detects a stroke of a damper DA having a piston rod 2A which enters and goes out of a cylinder 1A, and interposed between a vehicle body and a wheel comprises a sub-spring S2 arranged in series to a main spring (S1A) which elongates and contracts accompanied by the stroke of the damper DA, and set larger than the main spring in a spring constant. The stroke detection device 3A comprises a stroke sensor 30 which detects a deformation amount of the sub-spring S2, and stoke calculation means 31 which acquires the stroke of the damper DA from the detected value.

Description

  The present invention relates to a suspension device.

  In a vehicle, some suspension devices interposed between a vehicle body and a wheel include a stroke detection device that detects a stroke of a shock absorber. The adjustment can be automated and the ride quality can be improved.

  When the suspension device includes a swing arm (for example, a swing arm that supports the rear wheel of the two-wheeled vehicle) that supports the wheel so as to swing, and a shock absorber is interposed between the swing arm and the vehicle body. Can detect the swing of the swing arm with a potentiometer and determine the stroke of the shock absorber from the detected value. However, if the suspension device does not have a mechanism that swings or rotates according to the stroke of the shock absorber, such as a front fork that suspends the front wheel of the motorcycle, the potentiometer cannot be attached.

  Therefore, in the suspension device disclosed in Patent Document 1, the load of the suspension spring that is arranged in parallel with the shock absorber and elastically supports the vehicle body is detected by a load sensor, and the stroke of the shock absorber is obtained from the detected value.

  In the suspension devices disclosed in Patent Documents 2 and 3, a stroke sensor is inserted into the piston rod of the shock absorber, and the displacement of the piston rod relative to the cylinder is detected by this stroke sensor. According to this configuration, since the displacement of the piston rod is equal to the stroke of the shock absorber, the stroke of the shock absorber can be directly detected by the stroke sensor.

Japanese Patent Laid-Open No. 4-8930 JP-A-5-256308 Japanese Utility Model Publication No. 6-12849

  However, when adopting the configuration disclosed in Patent Document 1, load cells, piezoelectric elements, and the like are known as load sensors, but they are all expensive, and mass production is possible by incorporating the load sensor into a suspension device. Is difficult.

  In addition, as disclosed in Patent Documents 2 and 3, when a stroke sensor is inserted into a piston rod, it has been mass-produced in ordinary passenger cars, and although there is a track record, the stroke sensor is stroked by the same amount as the shock absorber stroke. Therefore, the stroke sensor is large.

  Accordingly, an object of the present invention is to provide a suspension device capable of downsizing the stroke sensor even if the stroke of the shock absorber is detected using the stroke sensor.

  Means for solving the above problems include a shock absorber provided between a vehicle body and a wheel, including a cylinder and a piston rod that enters and exits the cylinder, and a stroke detection device that detects a stroke of the shock absorber. The suspension includes: a main spring that expands and contracts with the stroke of the shock absorber; and a sub spring that is arranged in series with the main spring and has a spring constant set larger than that of the main spring. The detection device includes a stroke sensor that detects a deformation amount of the sub-spring, and a stroke calculation unit that obtains the stroke of the shock absorber from the detected value.

  According to the suspension device of the present invention, even if the stroke of the shock absorber is detected using the stroke sensor, the stroke sensor can be reduced in size.

It is the longitudinal cross-sectional view which showed the principal part of the suspension apparatus which concerns on one embodiment of this invention. It is the figure which showed in principle the principal part of the suspension apparatus which concerns on other embodiment of this invention. FIG. 3 is a longitudinal sectional view specifically showing a part of FIG. 2.

  A suspension device according to an embodiment of the present invention will be described below with reference to the drawings. The same reference numerals given throughout the several drawings indicate the same or corresponding parts.

  As shown in FIG. 1, the suspension device according to the present embodiment includes a shock absorber DA that includes a cylinder 1A and a piston rod 2A that enters and exits the cylinder 1A and is interposed between a vehicle body and a wheel. A stroke detection device 3A for detecting the stroke of the shock absorber DA, a suspension spring (main spring) S1A that expands and contracts with the stroke of the shock absorber DA, and the suspension spring S1A that is arranged in series with the suspension spring S1A. And a sub-spring S2 whose spring constant is set to be larger. The stroke detection device 3A includes a stroke sensor 30 that detects the amount of deformation of the subspring S2, and a stroke calculation means 31 that determines the stroke of the shock absorber DA from the detected value.

  Hereinafter, in detail, the suspension device according to the present embodiment is a front fork that suspends a front wheel of a saddle-ride type vehicle such as a two-wheeled vehicle or a three-wheeled vehicle. Since the structure of the front fork is well known, although not shown in detail, a pair of shock absorbers (only one shock absorber DA is shown and the other shock absorber is omitted) standing on both sides of the front wheel, and these A vehicle body side bracket (not shown) that connects the shock absorber DA and is connected to a vehicle body frame that is a skeleton of the vehicle body, and a wheel side bracket (not shown) that connects the lower end of each shock absorber DA to the axle of the front wheel. The front wheels are supported from both sides by a pair of shock absorbers DA. The suspension device may be a front fork that cantilever-supports the front wheels with a single shock absorber DA, or a rear cushion that suspends the rear wheels, or a suspension device other than a straddle-type vehicle such as an automobile. There may be.

  In the present embodiment, since the pair of shock absorbers DA has a common configuration, only one shock absorber DA will be described in detail below. The configuration of the shock absorber DA can be changed as appropriate, and one and the other of the pair of shock absorbers DA may have different configurations.

  In the present embodiment, the shock absorber DA includes a telescopic tube member T composed of a vehicle body side tube 4 and a wheel side tube 5, and the tube member T serves as an outer shell of the shock absorber DA. The vehicle body side tube 4 is formed to have a larger diameter than the wheel side tube 5, a vehicle body side bracket (not shown) is fixed to the outer periphery of the vehicle body side tube 4, and the wheel side tube 5 is attached to the lower end portion of the wheel side tube 5. Since the bracket (not shown) is fixed, when an impact due to road surface unevenness is input, the wheel side tube 5 enters and exits the vehicle body side tube 4 and the shock absorber DA strokes. The wheel side tube 5 may be formed to have a larger diameter than the vehicle body side tube 4, and the vehicle body side tube 4 may enter and exit the wheel side tube 5.

  In the tube member T, the upper side opening of the vehicle body side tube 4 is closed by the cap member 40, and the lower side opening of the wheel side tube 5 is closed by a wheel side bracket (not shown). Since the cylindrical gap formed between the overlapping portions of the side tube 5 is held by the inner periphery of the lower end portion of the vehicle body side tube 4 and is blocked by the annular seal member 41 slidably contacting the outer peripheral surface of the wheel side tube 5. The tube member T is hermetically sealed so that the liquid or gas accommodated therein does not leak to the outside.

  Further, the shock absorber DA stands at the bottom of the wheel side bracket (not shown) and rises at the axial center of the wheel side tube 5, and is held in a state of being suspended from the cap member 40. Piston rod 2A that enters and exits, and damping force generating means (not shown) that generates damping force that suppresses relative movement between the cylinder 1A and the piston rod 2A. Further, between the cap member 40 and the cylinder 1A, there is a suspension spring S1A that urges the shock absorber DA in the extending direction to elastically support the vehicle body, and a subspring S2 arranged in series with the suspension spring S1A. The stroke detecting device 3A detects the amount of deformation of the subspring S2, and the stroke of the shock absorber DA can be calculated from the detected value.

  In the present embodiment, the suspension spring S1A corresponds to the main spring according to the present invention, and includes a coil spring. The subspring S2 is a coil spring having a spring constant that is set larger than that of the suspension spring S1A and a short axial length. Between the suspension spring (main spring) S1A and the sub-spring S2, an annular intermediate spring seat 20 disposed on the outer periphery of the piston rod 2A and movable in the axial direction is interposed. That is, the suspension spring S1A and the subspring S2 are connected in series in the axial direction with the intermediate spring receiving seat 20 interposed therebetween, and the suspension spring S1A is a lower spring support fixed to the intermediate spring receiving seat 20 and the cylinder side. The sub spring S <b> 2 is interposed between the intermediate spring receiving seat 20 and the upper spring receiving seat 42 fixed to the cap member 40.

  The relationship between the deformation amount of the suspension spring S1A and the subspring S2 is that the deformation amount of the suspension spring S1A is a1, the deformation amount of the subspring S2 is a2, the spring constant of the suspension spring S1A is k1, and the spring constant of the subspring S2 is k2. Then, a1 / a2 = k2 / k1. Further, the spring constant k2 of the sub-spring S2 is set to be larger than the spring constant k1 of the suspension spring S1A (k1 <k2), for example, about 3 to 70 times the spring constant k1 of the suspension spring S1A. For this reason, the deformation amount a2 of the subspring S2 is reduced to about 1/3 to 1/70 of the deformation amount a1 of the suspension spring S1A.

  In this embodiment, the stroke detection device 3A has a stroke sensor 30 that detects the deformation amount a2 of the subspring S2, and a stroke calculation that calculates the stroke of the shock absorber DA from the value (a2) detected by the stroke sensor 30. Means 31 and an extension rod 32 which is held by the intermediate spring seat 20 and transmits the displacement of the intermediate spring seat 20 to the stroke sensor 30 are provided. The intermediate spring seat 20 and the stroke sensor 30 are preferably joined, but this is not a limitation.

  The stroke sensor 30 includes a cylindrical sensor cylinder 30a held by the cap member 40, and a sensor rod 30b arranged in series with the extension rod 32 to enter and exit the sensor cylinder 30a, and a sensor rod for the sensor cylinder 30a. The displacement of 30b (stroke of the stroke sensor 30) is set to be output as an electrical signal. The configuration of the stroke sensor 30 can be changed as appropriate.

  The stroke of the stroke sensor 30 is equal to the deformation amount a2 of the sub-spring S2, and the deformation amount a1 of the suspension spring S1A can be obtained by a1 = k2 · a2 / k1. The stroke of the shock absorber DA is equal to the sum of the deformation amounts a1 and a2 of the suspension spring S1A and the subspring S2, and can be obtained by a1 + a2. In the present embodiment, the stroke calculation means 31 for performing the calculation includes an in-vehicle control unit.

  In the form shown in FIG. 1, in the tube member T, gas is sealed outside the cylinder 1A to form an air chamber RG, and the pressure in the air chamber RG moves the sensor rod 30b toward the sensor cylinder 30a. Acts like a push. The volume of the air chamber RG expands and contracts with the stroke of the shock absorber DA, and the pressure of the air chamber RG changes. Therefore, the force pushing the sensor rod 30b due to the pressure of the air chamber RG also changes according to the stroke of the shock absorber DA. To do. For this reason, when the spring constant k2 of the subspring S2 is increased or the maximum deformation amount of the subspring S2 is set large, and the stroke calculation means 31 determines the deformation amount a1 of the suspension spring S1A, the sensor rod 30b By correcting for subtracting the amount pushed by the pressure in the chamber RG, the stroke of the shock absorber DA can be obtained accurately.

  When the sensor rod 30b is set not to be pushed toward the sensor cylinder 30a by the pressure of the air chamber RG, or when the sensor rod 30b is held so as not to move even if it is pushed by the pressure of the air chamber RG. The above correction is unnecessary.

  Hereinafter, the operation of the suspension device according to the present embodiment will be described.

  When the wheel side tube 5 is withdrawn from the vehicle body side tube 4 and the piston rod 2A is withdrawn from the cylinder 1A, and the shock absorber DA is stroked in the extending direction, the suspension spring S1A and the subspring S2 are extended. At this time, the intermediate spring seat 20 moves away from the cap member 40, the sensor rod 30b retracts from the sensor cylinder 30a, and the stroke sensor 30 detects the deformation amount a2 of the sub spring S2. Then, the stroke calculation means 31 obtains the stroke of the shock absorber DA based on the value (a2) detected by the stroke sensor 30 (= a1 + a2, a1 = k2 / a2 / k1, the sensor rod 30b is the pressure of the air chamber RG. Correction to subtract the amount pressed by.

  On the contrary, when the wheel side tube 5 enters the vehicle body side tube 4 and the piston rod 2A enters the cylinder 1A and the shock absorber DA strokes in the compression direction, the suspension spring S1A and the subspring S2 contract. At this time, the intermediate spring seat 20 approaches the cap member 40, the sensor rod 30b enters the sensor cylinder 30a, and the stroke sensor 30 detects the deformation amount a2 of the sub spring S2. Then, the stroke calculation means 31 obtains the stroke of the shock absorber DA based on the value (a2) detected by the stroke sensor 30 (= a1 + a2, a1 = k2 / a2 / k1, the sensor rod 30b is the pressure of the air chamber RG. Correction to subtract the amount pressed by.

  Hereinafter, the effect of the suspension apparatus according to the present embodiment will be described.

  In the present embodiment, the shock absorber DA includes a telescopic tube member T including a vehicle body side tube 4 and a wheel side tube 5, and the cylinder 1 </ b> A and the piston rod 2 </ b> A are disposed in the tube member T. A gas chamber RG is formed between the tube member T and the cylinder 1A. The stroke sensor 30 includes a sensor cylinder 30a and a sensor rod 30b that appears and disappears in the sensor cylinder 30a and is pushed toward the sensor cylinder 30a by the pressure of the air chamber RG. When obtaining the deformation amount a1 of the suspension spring S1A, the correction is made to subtract the amount by which the sensor rod 33b is pushed toward the sensor cylinder 30a by the pressure of the air chamber RG.

  According to the above configuration, the stroke of the shock absorber DA can be accurately obtained. However, the sensor rod 30b is set not to be pushed toward the sensor cylinder 30a by the pressure of the air chamber RG, or the air chamber RG When the sensor rod 30b is held so as not to move even when pressed by pressure, the above-described effect can be obtained without performing the above correction.

  In the present embodiment, the main spring is the suspension spring S1A that urges the shock absorber DA in the extending direction to elastically support the vehicle body.

  According to the said structure, the stroke of shock absorber DA can be calculated | required from the sum total of deformation amount a1, a2 of suspension spring S1A and subspring S2.

  Further, according to the above configuration, when the shock absorber DA is an upright shock absorber in which the cylinder 1A is connected to the wheel side and the piston rod 2A is connected to the vehicle body side as in the present embodiment, the stroke sensor It is easy to arrange 30 on a spring, and by doing in this way, it can control that an impact by road surface unevenness is transmitted to stroke sensor 30. However, the configuration of the shock absorber DA is not limited to the above, and may be an inverted shock absorber in which the cylinder 1A is connected to the vehicle body side and the piston rod 2A is connected to the wheel side.

  Further, in the present embodiment, the suspension device includes a cylinder 1A and a piston rod 2A that enters and exits the cylinder 1A and is interposed between the vehicle body and the wheel, and a stroke of the buffer DA. And a suspension spring (main spring) S1A that expands and contracts with the stroke of the shock absorber DA, and is arranged in series with the suspension spring S1A and has a spring constant greater than that of the suspension spring S1A. And a sub-spring S2 which is set to be large. The stroke detection device 3A includes a stroke sensor 30 that detects the deformation amount a2 of the sub-spring S2, and stroke calculation means 31 that calculates the stroke of the shock absorber DA from the detected value (a2). Yes.

  According to the above configuration, since the spring constant k2 of the sub spring S2 is set larger than the spring constant k1 of the suspension spring S1A, the deformation amount a2 of the sub spring S2 is smaller than the deformation amount a1 of the suspension spring S1A. Become. Therefore, even if the stroke of the shock absorber DA is detected using the stroke sensor 30, the stroke of the stroke sensor 30 can be smaller than the stroke of the shock absorber DA, so that the stroke sensor 30 can be downsized. .

  Subsequently, a suspension device according to another embodiment of the present invention will be described. In the suspension apparatus, the same reference numerals are assigned to the same configurations as those of the suspension apparatus according to the embodiment, and detailed description thereof is omitted. As shown in FIG. 2, the suspension device according to the present embodiment is a front fork that suspends the front wheels of a saddle-ride type vehicle, as in the case of one embodiment, and a pair of shock absorbers that stand on both sides of the front wheels ( Only one shock absorber DB is shown, and the other shock absorber is omitted), and a vehicle body side bracket (not shown) that connects these shock absorber DBs and is connected to a vehicle body frame that is a skeleton of the vehicle body, A wheel-side bracket 50 that connects the lower end of each shock absorber DB to the axle of the front wheel is provided, and the front wheel is supported from both sides by a pair of shock absorber DBs. The suspension device may be a front fork that cantilever-supports the front wheels with a single shock absorber DB, or a rear cushion that suspends the rear wheels, and may be a suspension device other than a straddle-type vehicle such as an automobile. There may be.

  Also in this embodiment, since the pair of shock absorbers DB has a common configuration, only one shock absorber DB will be described in detail below. The configuration of the shock absorber DB can be changed as appropriate, and one of the pair of shock absorbers DB may have a different configuration.

  In the present embodiment, the shock absorber DB also includes a telescopic tube member T composed of the vehicle body side tube 4 and the wheel side tube 5 as in the case of the one embodiment. It becomes the outer shell of the vessel DB and is sealed.

  The shock absorber DB includes a cylinder 1B that is held by the cap member 40 and stands on the axial center portion of the vehicle body side tube 4, an annular rod guide 11 that closes a lower opening of the cylinder 1B, and a wheel side bracket 50. A piston rod 2B that stands up at the bottom and is pivotally supported by the rod guide 11 and enters and exits the cylinder 1B; a piston 6 that is fixed to the upper end of the piston rod 2B and is slidably inserted into the cylinder 1B; and the cylinder 1B The base rod 7 stands on the shaft center portion on the side opposite to the piston rod, the base member 8 is fixed to the lower end portion of the base lot 7, and is slidably inserted between the base rod 7 and the cylinder 1B. An annular free piston 9 is provided.

  Further, a suspension spring S1B is provided between the rod guide 11 and the vehicle body side bracket 50 to elastically support the vehicle body by urging the shock absorber DB in the extending direction, and between the cap member 40 and the free piston 9. Is provided with a pressure spring S3 for urging the free piston 9 downward in FIG. 2 and a subspring S4 arranged in series with the pressure spring S3. The stroke detection device 3B uses the subspring S4. The amount of deformation is detected, and the stroke of the shock absorber DB can be calculated from the detected value.

  A fluid chamber L filled with hydraulic fluid is formed in the cylinder 1B of the shock absorber DB. The fluid chamber L includes an extension side chamber L1 and a pressure side chamber L2 defined by the piston 6, and the pressure side chamber. It consists of a liquid reservoir chamber L3 partitioned by L2 and the base member 8. As the hydraulic fluid, oil called hydraulic fluid, or liquid such as water or an aqueous solution is used. The liquid reservoir L3 is partitioned from an air chamber G in which gas is enclosed by a free piston 9. A reservoir R is formed between the cylinder 1B and the tube member T. The reservoir R is filled with hydraulic fluid and gas.

  As shown in FIG. 3, the cylinder 1B is arranged on the lower side in FIG. 3 and is slidably contacted with the piston 6. The cylinder 1B is arranged on the upper side in FIG. 9 includes a base side cylinder 13 that is in sliding contact, and a piston side cylinder 12 is screwed to the inner periphery of the lower end of the base side cylinder 13. In the upper part of the base side cylinder 13, there is provided an enlarged diameter portion 13a whose inner circumference is formed larger than the inner circumference of other portions, and the inside and outside of the cylinder 1B are communicated with the lower portion of the enlarged diameter portion 13a. A through hole 13b is formed.

  Returning to FIG. 2, the piston 6 that divides the expansion side chamber L1 and the compression side chamber L2 is formed with an expansion side piston passage 6a and a compression side piston passage 6b that communicate the expansion side chamber L1 and the compression side chamber L2. In addition, the extension side damping valve 60 that allows the flow of the hydraulic fluid to move from the extension side chamber L1 to the pressure side chamber L2 through the extension side piston passage 6a and blocks the flow in the opposite direction, and the pressure side piston passage 6b from the pressure side chamber L2 are allowed. A pressure-side check valve 61 that allows the flow of the hydraulic fluid moving to the extension side chamber L1 and prevents the flow in the opposite direction is stacked. In the present embodiment, the resistance that the expansion side damping valve 60 gives to the hydraulic fluid that passes through the expansion side piston passage 6a is relatively large, and the resistance that the compression side check valve 61 gives to the hydraulic fluid that passes through the compression side piston passage 6b is compared. Is set to be smaller. However, the specifications of the valve stacked on the piston 6 can be changed as appropriate according to the desired damping force characteristics.

  The base member 8 that divides the pressure side chamber L2 and the liquid reservoir chamber L3 is formed with an extension side base member passage 8a and a pressure side base member passage 8b that communicate the pressure side chamber L2 and the liquid reservoir chamber L3. An extension check valve 80 that allows the flow of hydraulic fluid to move from the liquid reservoir L3 to the pressure side chamber L2 through the member passage 8a and prevents the flow in the opposite direction, and the pressure side base member passage 8b from the pressure side chamber L2 to the liquid. A compression side damping valve 81 that allows the flow of the working fluid moving to the reservoir chamber L3 and prevents the flow in the opposite direction is stacked. In the present embodiment, the resistance that the expansion side check valve 80 gives to the hydraulic fluid that passes through the expansion side base member passage 8a is relatively small, and the resistance that the compression side damping valve 81 gives to the hydraulic fluid that passes through the compression side damping passage 8b is It is set to be relatively large. However, the specification of the valve laminated on the base member 8 can also be changed as appropriate according to the desired damping force characteristics.

  As shown in FIG. 3, the free piston 9 that partitions the liquid storage chamber L3 and the air chamber G includes a main body portion 9a formed in an annular shape, and a pair of upper and lower annular outer peripheral seals attached to the outer periphery of the main body portion 9a. 9b, 9c, and an annular inner peripheral seal 9d attached to the inner periphery of the main body 9a, and can move between the base member 7 and the cap member 40 in the axial direction. The inner peripheral seal 9 d is always in sliding contact with the outer peripheral surface of the base rod 7 and closes the inner periphery of the free piston 9. The upper outer peripheral seal 9 b is always in sliding contact with the inner peripheral surface of the enlarged diameter portion 13 a and closes the outer periphery of the free piston 9. On the other hand, the lower outer peripheral seal 9c is in sliding contact with the inner peripheral surface of the base side cylinder 13 until it reaches the enlarged diameter portion 13a and closes the outer periphery of the free piston 9, but reaches the enlarged diameter portion 13a. The space between the expanded diameter portion 13a is not completely blocked and the working fluid leaks out. Then, the leaked hydraulic fluid can move to the reservoir R through the through hole 13b. By doing in this way, it can prevent that the cylinder 1B internal pressure becomes excessive.

  A pressure spring S 3 that urges the free piston 9 downward in FIGS. 2 and 3 pressurizes the liquid chamber L via the free piston 9. Moreover, in this Embodiment, the said pressurization spring S3 is corresponded to the main spring which concerns on this invention, and consists of a coil spring. The sub-spring S4 provided in series with the pressure spring S3 is a disc spring having a spring constant set larger than that of the pressure spring S3, and the axial length is much shorter than that of the pressure spring S3. Between the pressure spring (main spring) S3 and the sub-spring S4, an annular intermediate spring seat 70 that is disposed on the outer periphery of the base rod 7 and is movable in the axial direction is interposed. That is, the pressure spring S3 and the sub spring S4 are connected in series in the axial direction with the intermediate spring seat 70 interposed therebetween, and the pressure spring S3 is fixed to the intermediate spring seat 70 and the free piston 9. The sub spring S <b> 4 is interposed between the intermediate spring receiving seat 70 and the cap member 40.

  The relationship between the amount of deformation of the pressure spring S3 and the subspring S4 is that the amount of deformation of the pressure spring S3 is a3, the amount of deformation of the subspring S4 is a4, the spring constant of the pressure spring S3 is k3, and the spring constant of the subspring S4. Is k4, a3 / a4 = k4 / k3. The spring constant k4 of the sub-spring S4 is set to be larger than the spring constant k3 of the pressure spring S3 (k3 <k4), and is, for example, about 3 to 70 times the spring constant k3 of the pressure spring S3. The For this reason, the deformation amount a4 of the subspring S4 is reduced to about 1/3 to 1/70 of the deformation amount a3 of the pressure spring S3.

  The stroke detection device 3B that calculates the stroke of the shock absorber DB from the deformation amount a4 of the subspring S4 is similar to the embodiment in the present embodiment as well as the stroke sensor 33 that detects the deformation amount a4 of the subspring S4. The stroke calculating means 34 for calculating the stroke of the shock absorber DB from the value (a4) detected by the stroke sensor 33 and the displacement of the intermediate spring receiving seat 70 held by the intermediate spring receiving seat 70 to the stroke sensor 33. An extension rod 35 is provided. The intermediate spring seat 70 and the stroke sensor 33 are preferably joined, but this is not a limitation.

  The stroke sensor 33 includes a cylindrical sensor cylinder 33a that is held by the cap member 40, and a sensor rod 33b that is arranged in series with the extension rod 35 and enters and exits the sensor cylinder 33a, and a sensor rod for the sensor cylinder 33a. The displacement 33b (stroke of the stroke sensor 33) is set to be output as an electrical signal. The configuration of the stroke sensor 33 can be changed as appropriate.

  The stroke of the stroke sensor 33 is equal to the deformation amount a4 of the subspring S4, and the deformation amount a3 of the pressure spring S3 can be obtained by a3 = k4 · a4 / k3. The stroke of the shock absorber DB is equal to the displacement of the piston rod 2B relative to the cylinder 1B, the displacement of the piston rod 2B is N, the displacement of the free piston 9 is M, the cross-sectional area of the piston rod 2B is X1, and the liquid reservoir L3 The area of the circle whose diameter is the outer diameter of the base rod 7 with which the inner peripheral seal 9d is slid is subtracted from the area of the circle whose diameter is the inner diameter of the base side cylinder 13 with which the lower outer peripheral seal 9c is in sliding contact. (Area) is X2, N = M × X2 / X1. The displacement M of the free piston 9 is equal to the sum of the deformation amounts a3 and a4 of the pressure spring S3 and the subspring S4 and can be obtained by a3 + a4. Therefore, the stroke of the shock absorber DB is determined from the deformation amount a4 of the subspring S4. Can be requested. In the present embodiment, the stroke calculation means 34 for performing the calculation is composed of an in-vehicle control unit.

  In the form shown in FIG. 3, the pressure in the air chamber G acts to push the sensor rod 33b toward the sensor cylinder 33a. The volume of the air chamber G expands and contracts due to the displacement of the free piston 9 accompanying the stroke of the shock absorber DB, and the pressure of the air chamber G changes. Therefore, the force pushing the sensor rod 33b due to the pressure of the air chamber G is also affected by the shock absorber DB. It changes according to the stroke. Therefore, when the spring constant k4 of the sub-spring S4 is increased or the maximum deformation amount of the sub-spring S4 is set large, and the stroke calculating means 34 determines the deformation amount a3 of the pressure spring S3, the sensor rod 33b By correcting for subtracting the amount pushed by the pressure of the air chamber G, the stroke of the shock absorber DB can be accurately obtained.

  When the sensor rod 33b is set so as not to be pushed toward the sensor cylinder 33a by the pressure of the air chamber G, or when the sensor rod 33b is held so as not to move even if pressed by the pressure of the air chamber G. The above correction is unnecessary.

  Hereinafter, the operation of the shock absorber DB according to the present embodiment will be described.

  When the wheel side tube 5 retreats from the vehicle body side tube 4 and the piston rod 2B retreats from the cylinder 1B, and the shock absorber DB strokes in the extending direction, the hydraulic fluid in the expansion side chamber L1 to be reduced is reduced by the expansion side damping valve 60. And moves to the compression side chamber L2 through the extension side piston passage 6a, so that the shock absorber DB generates an extension side damping force due to the resistance of the extension side damping valve 60.

  In addition, when the shock absorber DB strokes in the extending direction, the piston rod volume (= N × X1) retreating from the cylinder 1B and the cylinder internal volume increase. It opens and moves from the liquid reservoir chamber L3 to the compression chamber L2 through the extended base member passage 8a. For this reason, the free piston 9 moves downward in FIGS. 2 and 3, and the pressure spring S3 and the subspring S4 extend. At this time, the intermediate spring seat 70 moves away from the cap member 40, the sensor rod 33b retracts from the sensor cylinder 33a, and the stroke sensor 33 detects the deformation amount a4 of the sub spring S4. The stroke calculation means 34 obtains the stroke of the shock absorber DB from the value (a4) detected by the stroke sensor S4 (N = M × X2 / X1, M = a3 + a4, a3 = k4 · a4 / k3, sensor rod 33b is a correction for subtracting the amount 33b pushed by the pressure in the air chamber G).

  On the contrary, when the wheel side tube 5 enters the vehicle body side tube 4 and the piston rod 2B enters the cylinder 1B and the shock absorber DB strokes in the compression direction, the hydraulic fluid in the compression side chamber L2 to be reduced is compressed side reverse. The stop valve 61 is opened and moved to the expansion side chamber L2 through the pressure side piston passage 6b.

  Further, when the shock absorber DB strokes in the compression direction, the piston rod volume (= N × X1) that has entered the cylinder 1B and the cylinder internal volume decrease, so that the hydraulic fluid corresponding to this opens the compression side damping valve 81, It moves from the pressure side chamber L2 to the liquid reservoir chamber L3 through the pressure side base member passage 8b. For this reason, the shock absorber DB generates a pressure side damping force due to the resistance of the pressure side check valve 61 and the pressure side damping valve 81. At this time, the free piston 9 moves upward in FIGS. 2 and 3, and the pressure spring S3 and the subspring S4 are compressed, so that the intermediate spring seat 70 approaches the cap member 40 and the sensor rod 33b is moved. The sensor cylinder 33a is entered, and the stroke sensor 33 detects the deformation amount a4 of the sub spring S4. Then, the stroke calculation means 34 obtains the stroke of the shock absorber DB from the value (a4) detected by the stroke sensor 33 (N = M × X2 / X1, M = a3 + a4, a3 = k4 · a4 / k3, sensor rod 33b is a correction for subtracting the amount 33b pushed by the pressure in the air chamber G).

  It continues and demonstrates the effect of the suspension apparatus which concerns on this Embodiment.

  In the present embodiment, the sub spring S4 is a disc spring.

  According to the said structure, compared with the case where subspring S4 consists of coil springs, the axial direction length of subspring S4 can be shortened, and it can suppress that buffer DB is bulky in an axial direction. However, the sub-spring S4 may be a coil spring as in the embodiment, and the sub-spring S2 in the embodiment may be changed to a disc spring.

  Further, in the present embodiment, in the cylinder 1B, an air chamber G that is partitioned from the liquid chamber L by the free piston 9 and in which gas is sealed is formed. The stroke sensor 33 includes a sensor cylinder 33 a and a sensor rod 33 b that appears and disappears in the sensor cylinder 33 a and is pushed toward the sensor cylinder 33 a by the pressure of the air chamber G. When the deformation amount a3 of the pressure spring S3, which is a spring, is obtained, correction is made to subtract the amount by which the sensor rod 33b is pushed toward the sensor cylinder 33a by the pressure in the air chamber G.

  According to the above configuration, the stroke of the shock absorber DB can be accurately obtained. However, the pressure of the air chamber G is set so that the sensor rod 33b is not pushed to the sensor cylinder 33a side, When the sensor rod 33b is held so as not to move even when pressed by pressure, the above-described effect can be obtained without performing the above correction.

  Further, in the present embodiment, the shock absorber DB is held in the liquid chamber L formed in the cylinder 1B and filled with the working fluid and the upper end portion (tip portion) of the piston rod 2B to extend the liquid chamber L. A piston 6 that is divided into a side chamber L1 and a pressure side chamber L2, and a free piston 9 that is slidably inserted into the anti-piston rod side in the cylinder 1B and divides the liquid chamber L in the cylinder 1B. The main spring is a pressurizing spring S3 that pressurizes the liquid chamber L via the free piston 9.

  According to the above configuration, the deformation amount a3 of the pressure spring S3 can be obtained from the deformation amount a4 of the sub spring S4. Then, the displacement M of the free piston 9 can be obtained from the sum of the deformation amounts a3 and a4 of the pressure spring S3 and the subspring S4, and the stroke of the shock absorber DB can be obtained from the displacement of the free piston M. When the suspension device includes the pressurizing spring S3, the stroke a of the shock absorber DB can be obtained even if the deformation amount a3 of the pressurizing spring S3 is directly detected by the stroke sensor 33 and the stroke of the shock absorber DB is obtained from this value. Although the stroke sensor 33 can be reduced in size as compared with the case where it is directly detected by the stroke sensor 33, the stroke sensor 33 can be further reduced in size by the above configuration.

  Further, according to the above configuration, when the shock absorber DB is an inverted shock absorber in which the cylinder 1B is connected to the vehicle body side and the piston rod 2B is connected to the wheel side as in the present embodiment, the stroke sensor 33 is used. Can be arranged on the spring, and by doing so, it is possible to suppress the impact due to the road surface unevenness being transmitted to the stroke sensor 33. However, even with such an inverted shock absorber DB, a subspring is provided in series with the suspension spring S1B, and the deformation amount of the suspension spring S1B is obtained from the deformation amount of the subspring, similarly to the embodiment. It is good. Moreover, even if it is shock absorber DB provided with the said free piston 9, it may be set as an inverted type by connecting the cylinder 1B to the wheel side and connecting the piston rod 2B to the vehicle body side.

  Further, in the present embodiment, a shock absorber DB that includes a cylinder 1B and a piston rod 2B that enters and exits the cylinder 1B and is interposed between the vehicle body and the wheel, and a stroke that detects the stroke of the shock absorber DB. A pressure spring (main spring) S3 that includes a detection device 3B, and expands and contracts with the stroke of the shock absorber, and is arranged in series with the pressure spring S3 and has a spring constant larger than that of the pressure spring S3. And a sub-spring S4. The stroke detection device 3B includes a stroke sensor 33 that detects the deformation amount a4 of the sub-spring S4, and a stroke calculation means 34 that calculates the stroke of the shock absorber DB from the detected value (a4). Yes.

  According to the above configuration, since the spring constant k4 of the sub spring S4 is set to be larger than the spring constant k3 of the pressure spring S3, the deformation amount a4 of the sub spring S4 is larger than the deformation amount a3 of the pressure spring k3. Becomes smaller. Therefore, even if the stroke of the shock absorber DB is detected using the stroke sensor 33, the stroke of the stroke sensor 33 may be smaller than the stroke of the shock absorber DB, and therefore the stroke sensor 33 can be downsized. .

  Although preferred embodiments of the present invention have been described in detail above, it should be understood that modifications, variations and changes may be made without departing from the scope of the claims.

DA, DB Buffer L Liquid chamber L1 Stretch side chamber L2 Pressure side chamber G, RG Air chamber S1A Suspension spring (main spring)
S2, S4 Sub spring S3 Pressure spring (main spring)
T Tube member 1A, 1B Cylinder 2A, 2B Piston rod 3A, 3B Stroke detection device 4 Car body side tube 5 Wheel side tube 6 Piston 9 Free piston 30, 33 Stroke sensor 30a, 33a Sensor cylinder 30b, 33b Sensor rod 31, 34 Stroke Calculation means

Claims (6)

In a suspension system comprising a cylinder and a shock absorber interposed between the vehicle body and the wheel, and a piston rod that enters and exits the cylinder, and a stroke detection device that detects the stroke of the shock absorber,
A main spring that expands and contracts with the stroke of the shock absorber, and a sub spring that is arranged in series with the main spring and has a spring constant set larger than that of the main spring,
The above-mentioned stroke detection device is provided with a stroke sensor which detects the amount of deformation of the above-mentioned subspring, and a stroke calculation means which calculates the stroke of the above-mentioned shock absorber from the detected value.   The suspension device according to claim 1, wherein the main spring is a suspension spring that urges the shock absorber in an extending direction to elastically support the vehicle body. The shock absorber includes a telescopic tube member composed of a vehicle body side tube and a wheel side tube,
The cylinder and the piston rod are arranged in the tube member, and a gas chamber is formed between the tube member and the cylinder by enclosing gas,
The stroke sensor includes a sensor cylinder and a sensor rod that appears and disappears in the sensor cylinder and is pushed toward the sensor cylinder by the pressure of the air chamber.
3. The correction according to claim 2, wherein when the amount of deformation of the suspension spring is determined by the stroke calculation means, a correction is made to subtract the amount by which the sensor rod is pushed toward the sensor cylinder by the pressure of the air chamber. Suspension device. The shock absorber includes a liquid chamber formed in the cylinder and filled with a working fluid, a piston that is held at a tip of the piston rod and divides the liquid chamber into an extension side chamber and a pressure side chamber, and the cylinder A free piston that is slidably inserted on the side opposite to the piston rod and partitions the liquid chamber in the cylinder,
The suspension apparatus according to claim 1, wherein the main spring is a pressurizing spring that pressurizes the liquid chamber via the free piston. In the cylinder, an air chamber that is partitioned from the liquid chamber by the free piston and in which gas is sealed is formed,
The stroke sensor includes a sensor cylinder and a sensor rod that appears and disappears in the sensor cylinder and is pushed toward the sensor cylinder by the pressure of the air chamber.
5. The correction according to claim 4, wherein when the deformation amount of the pressurizing spring is obtained by the stroke calculation means, a correction is made to subtract an amount by which the sensor rod is pushed toward the sensor cylinder by the pressure of the air chamber. Suspension system.   The suspension device according to any one of claims 1 to 5, wherein the sub-spring is a disc spring.

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