Air spring, vehicle height detection system, and vehicle height detection method

Abstract

Provided are an air spring, a vehicle height detection system, and a vehicle height detection method capable of accurately detecting a vehicle height while reducing cost.　This air spring 1 for a vehicle comprises pistons 12, 12A that stroke in conjunction with the operation of a suspension, and cylindrical air sleeves 13, 13A that have one end connected to a body side and the other end connected to the pistons 12, 12A, and have outer surfaces 130A that come into contact with outer peripheral surfaces 120 of the pistons 12, 12A by means of the action of air pressure. The outer peripheral surfaces 120 of the pistons 12, 12A are provided with contact regions 200, 200A in which a plurality of energization parts 201 and a plurality of insulation parts 202 are arranged side by side alternately adjacent to each other along the stroke direction. On the outer surfaces 130A of the air sleeves 13, 13A, regions in contact with at least the contact regions 200, 200A among regions that come into contact with the outer peripheral surfaces 120 of the pistons 12, 12A are formed of conductive elastic bodies.

Description

Air spring, vehicle height detection system, and vehicle height detection method

[0001] The present invention relates to an air spring applied to a vehicle, and a vehicle height detection system and method for detecting the height of the vehicle.

[0002] Generally, in automobile suspensions, for example, vehicles equipped with air suspensions that support the vehicle height using air pressure are equipped with a function to adjust the vehicle height. In order to adjust the vehicle height, it is necessary to detect the vehicle height. For example, a potentiometer or a Hall element sensor is used as a vehicle height sensor to detect the vehicle height.

[0003] For example, Patent Document 1 discloses a vehicle height adjustment device for an air suspension vehicle that includes left and right air springs that support the chassis frame, a vehicle height adjustment valve that supplies and discharges compressed air to each of the left and right air springs, left and right vehicle height sensors that electrically detect the left and right vehicle heights, respectively, and a controller that controls the vehicle height adjustment valves so that the average value of the left and right vehicle heights detected by the left and right vehicle height sensors becomes a predetermined reference value.

[0004] Japanese Patent Application Laid-Open No. 2001-213129

[0005] However, in the vehicle height adjusting device described in Patent Document 1, the vehicle height sensor (e.g., a potentiometer) must be placed in the limited space in the air suspension, which limits the degree of freedom in layout. Furthermore, brackets and other components are required to mount the vehicle height sensor, and the labor required for assembling them is also significant, which is one of the reasons why the suspension system is expensive.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an air spring, a vehicle height detection system, and a vehicle height detection method that are capable of detecting vehicle height with high accuracy while reducing costs.

[0007] [1] In order to achieve the above object, the present invention provides an air spring for a vehicle, comprising: a piston that strokes in accordance with the operation of a suspension; and a cylindrical air sleeve having one end connected to the body and the other end connected to the piston, and whose outer surface comes into contact with the outer peripheral surface of the piston when air pressure is applied; wherein the outer peripheral surface of the piston is provided with a contact area in which a plurality of conductive parts and a plurality of insulating parts are arranged adjacent to each other along the stroke direction; and the outer surface of the air sleeve, among the areas that come into contact with the outer peripheral surface of the piston, at least the area that comes into contact with the contact area is formed of a conductive elastic material.

[0008] [2] More preferably, the present invention is characterized in that, in the air spring described in [1], the air sleeve comprises an elastic outer cover layer on the outer surface side, an elastic inner cover layer arranged on the inner circumferential side of the outer cover layer, and reinforcing layers bonded to the inner circumferential surface of the outer cover layer and the outer circumferential surface of the inner cover layer, and a conductive layer formed of an elastic material having conductivity is bonded to the surface of the outer cover layer in an area that comes into contact with the contact area.

[0009] [3] More preferably, in the air spring according to [1], the present invention is characterized in that the plurality of current-carrying portions have the same width dimension in the arrangement direction and are arranged at equal intervals.

[0010] [4] More preferably, the present invention is characterized in that, in the air spring described in [1], the plurality of conductive parts have the same width dimension in the arrangement direction, and the contact areas include a first contact area in which the arrangement interval of the plurality of conductive parts becomes narrower toward one side in the stroke direction of the piston, and a second contact area arranged alongside the first contact area in the circumferential direction of the piston, and in which the arrangement interval of the plurality of conductive parts becomes wider toward the one side in the stroke direction of the piston, and the outer surface of the air sleeve is formed such that the areas in contact with the first contact area and the second contact area are each formed from a conductive elastic material, and the areas other than the areas in contact with the first contact area and the second contact area are formed from an insulating elastic material.

[0011] [5] The present invention also provides a vehicle height detection system for detecting the height of a vehicle, comprising: an air spring according to any one of [1] to [4]; a first harness electrically connected to the contact area of ​​the piston of the air spring; a second harness electrically connected to a portion of the air sleeve of the air spring formed by the conductive elastic body; and a controller connected to each of the first harness and the second harness, measuring a change over time in resistance value between the air sleeve and the piston, calculating a stroke amount of the piston based on the measured change over time in resistance value, and detecting the height of the vehicle based on the calculated stroke amount.

[0012] [6] The present invention is also characterized in that, in a vehicle height detection method for detecting the height of a vehicle, a change over time in a resistance value between the air sleeve and the piston of the air spring described in any one of [1] to [4] is measured, a stroke amount of the piston is calculated based on the measured change over time in the resistance value, and the height of the vehicle is detected based on the calculated stroke amount.

[0013] According to the present invention, it is possible to accurately detect vehicle height while reducing costs. Problems, configurations, and effects other than those described above will become apparent from the following description of the embodiments.

[0014] 1 is a diagram showing an example of the configuration of an air spring according to an embodiment of the present invention; FIG. 2 is a side view showing one side of a piston of the air spring; FIG. 3 is an external perspective view showing an example of the configuration of an air sleeve of the air spring; FIG. 4 is a schematic cross-sectional view showing a partial cross-section of the air sleeve shown in FIG. 3; FIG. 5 is an explanatory view explaining the state of the air spring when the piston is actuated; and FIG. 6 is a graph showing the state of change in resistance value over time. FIG. 6 is a side view showing one side of a piston of an air spring according to a modified example of the present invention; FIG. 7 is an external perspective view showing an example of the configuration of an air sleeve of an air spring according to a modified example of the present invention; and FIG. 8 is a graph showing the state of change in resistance value over time in the modified example of the present invention.

[0015] Hereinafter, an air spring used in a suspension of an automobile will be described as an example of one aspect of an air spring according to an embodiment of the present invention. Also, a vehicle height detection system and a vehicle height detection method for detecting the vehicle height of an automobile will be described as an example of one aspect of a vehicle height detection system and a vehicle height detection method according to an embodiment of the present invention.

[0016] <Configuration of Air Spring 1> First, the configuration of the air spring 1 will be described with reference to FIGS.

[0017] Fig. 1 is a diagram showing an example of the configuration of an air spring 1 according to an embodiment of the present invention. Fig. 2 is a side view showing one side of a piston 12 of the air spring 1. Fig. 3 is an external perspective view showing an example of the configuration of an air sleeve 13 of the air spring 1. Fig. 4 is a schematic cross-sectional view showing a partial cross-section of the air sleeve 13 shown in Fig. 3. In Figs. 1 and 4, cross-sectional portions are not hatched to make the structure easier to see.

[0018] As shown in FIG. 1 , the air spring 1 includes a chamber 11 connected to the body side, a piston 12 connected to the tire side via a suspension (not shown), and a cylindrical air sleeve 13 connecting the chamber 11 and the piston 12.

[0019] The piston 12 strokes in response to the operation of the suspension, as indicated by the black double-headed arrow in Figure 1. Specifically, the piston 12 contracts when the suspension operates in a direction that lowers the vehicle height, and expands when the suspension operates in a direction that increases the vehicle height.

[0020] As shown in FIG. 2, the outer peripheral surface 120 of the piston 12 is provided with a contact area 200 in which a plurality of conductive portions 201 that conduct electricity and a plurality of insulating portions 202 that do not conduct electricity are arranged adjacent to each other alternately along the stroke direction (axial direction) of the piston 12.

[0021] Each of the plurality of conductive parts 201 is electrically conductive, has a rectangular shape with a long side in the circumferential direction of the piston 12 and a short side in the axial direction, and is arranged at equal intervals. Therefore, the plurality of insulating parts 202 arranged between the plurality of conductive parts 201 are also arranged at equal intervals.

[0022] It should be noted that the multiple conductive portions 201 do not necessarily have to be formed in the same shape, and in this embodiment, it is sufficient that they at least have the same width dimension in the arrangement direction (the dimension of the short side in the axial direction of the piston 12).

[0023] For example, when the outer peripheral surface 120 of the piston 12 is formed as a conductive surface, the contact area 200 can be formed by attaching an insulating sheet (e.g., a film sheet) to the outer peripheral surface 120 of the piston 12 and cutting out portions that will become the multiple current-carrying portions 201. Alternatively, for example, the contact area 200 may be formed by attaching an insulating sheet on which multiple conductors are attached at equal intervals to the outer peripheral surface 120 of the piston 12.

[0024] In Figure 2, the contact area 200 is formed in a rectangular shape with its long side in the axial direction of the piston 12, but this is not limited to this, and there are no particular restrictions on the external shape as long as it is possible to arrange multiple conductive parts 201 and multiple insulating parts 202 alternately along the stroke direction (axial direction) of the piston 12.

[0025] 1 , a first harness 21 is connected to the outer circumferential surface 120 of the piston 12. The other end of the first harness 21 is connected to the controller X. If the outer circumferential surface 120 of the piston 12 is an insulating surface, the first harness 21 needs to be connected to one of the plurality of current-carrying portions 201 of the contact area 200.

[0026] As shown in FIG. 1, one end of the air sleeve 13 in the extension direction is fixed to the chamber 11 by crimping the outer surface 130A side with a crimping ring 14A, and the other end of the air sleeve 13 in the extension direction is fixed to the piston 12 by crimping the inner surface 130B side with a crimping ring 14B.

[0027] 3, the air sleeve 13 has a small cylinder portion 31 disposed at one end in the extension direction and formed as a cylinder with a small diameter, a large cylinder portion 32 disposed at the other end in the extension direction and formed as a cylinder with a large diameter, and a tapered cylinder portion 33 disposed between the small cylinder portion 31 and the large cylinder portion 32 and formed so that the diameter gradually increases from the small cylinder portion 31 toward the large cylinder portion 32. The small cylinder portion 31, tapered cylinder portion 33, and large cylinder portion 32 are formed as a continuous, integrated unit.

[0028] As shown in FIG. 4 , the air sleeve 13 includes an outer cover layer 301 on the outer surface 130A side, an inner cover layer 302 disposed on the inner circumferential side of the outer cover layer 301, and a reinforcing layer 303 bonded to each of the inner circumferential surface of the outer cover layer 301 and the outer circumferential surface of the inner cover layer 302.

[0029] The outer cover layer 301 and the inner cover layer 302 are each made of an insulating elastic material such as rubber. The reinforcing layer 303 is made of a reinforcing hard material containing, for example, nylon fibers. Note that in Figure 4, nylon fibers are indicated by circles. In this embodiment, the reinforcing layer 303 has a first reinforcing layer 303A bonded to the outer cover layer 301 and a second reinforcing layer 303B bonded to the inner cover layer 302.

[0030] Therefore, the air sleeve 13 is composed of four layers, namely, an outer cover layer 301, a first reinforcing layer 303A, a second reinforcing layer 303B, and an inner cover layer 302, in the small tubular portion 31, the tapered tubular portion 33, and the large tubular portion 32.

[0031] When the piston 12 strokes in the contraction direction (toward the body in FIG. 1 ), the air sleeve 13 is drawn in toward the inner circumferential surface 130B while the outer surface 130A is in contact with the outer circumferential surface 120 of the piston 12. This increases the area of ​​the outer surface 130A of the air sleeve 13 that is in contact with the outer circumferential surface 120 of the piston 12.

[0032] Conversely, when the piston 12 strokes in the extension direction (toward the tire in FIG. 1 ), the outer surface 130A of the air sleeve 13, which had been curled toward the inner circumferential surface 130B, returns to its original position. As a result, the area of ​​the outer surface 130A of the air sleeve 13 that comes into contact with the outer circumferential surface 120 of the piston 12 is reduced.

[0033] In this way, as the piston 12 strokes, the area of ​​outer surface 130A of air sleeve 13 that contacts outer surface 120 of piston 12 varies. The contact area between outer surface 130A of air sleeve 13 and outer surface 120 of piston 12 is kept in tight contact with each other by the air pressure acting inside air sleeve 13.

[0034] As shown in Figures 3 and 4, a conductive layer 304 made of a conductive elastic material is bonded to a portion of the surface of the outer cover layer 301 along the extension direction (i.e., the stroke direction of the piston 12).

[0035] Specifically, the conductive layer 304 is bonded to a portion of the surface of the outer cover layer 301, from the tip of the small cylindrical portion 31, which is one end of the air sleeve 13, to the tip of the large cylindrical portion 32, which is the other end of the air sleeve 13.

[0036] In this embodiment, the conductive layer 304 does not necessarily have to be bonded to a portion of the surface of the outer cover layer 301, but may alternatively, for example, be bonded to cover the entire surface of the outer cover layer 301.

[0037] The elastomer forming the conductive layer 304 is made of an insulating rubber mixed with a conductive material such as finely powdered carbon black or metal powder, thereby achieving electrical conductivity. The resistance of an internally conductive elastomer to electrical current flow is generally expressed as a volume resistivity (Ω·cm), which corresponds to the volume resistance per unit volume. For the air sleeve 13 according to this embodiment, it is desirable to use an elastomer with a volume resistivity adjusted to approximately 10 to 1000 Ω·cm.

[0038] Conductive layer 304, together with outer cover layer 301, constitutes outer surface 130A of air sleeve 13 and contacts contact area 200 of piston 12. Therefore, the range of contact area of ​​conductive layer 304 with contact area 200 of piston 12 varies depending on the stroke of piston 12.

[0039] 1, the second harness 22 is connected to the end of the conductive layer 304 on the small tube portion 31 side. The other end of the second harness 22 is connected to the controller X. Note that when the crimping ring 14A is in contact with the conductive layer 304 of the air sleeve 13 and crimps the outer surface 130A side, the second harness 22 may be connected to the crimping ring 14A.

[0040] When a voltage is applied between the first harness 21 and the second harness 22, electrical continuity occurs between the air sleeve 13 and the piston 12 via the contact portion between the conductive layer 304 and the contact area 200 of the piston 12, causing a current to flow. The resistance value R between the air sleeve 13 and the piston 12 is proportional to the area of ​​the conductive portion of the air sleeve 13.

[0041] Specifically, the conductive portion of the air sleeve 13 is the region from the connection position of the second harness 22 on the conductive layer 304 to the position where contact with the contact area 200 of the piston 12 begins, and changes in proportion to the stroke of the piston 12.

[0042] In this embodiment, the width (dimension in the short side direction) of the conductive layer 304 along the circumferential direction of the air sleeve 13 is approximately constant at any point along the extension direction of the air sleeve 13. Therefore, the resistance value R between the air sleeve 13 and the piston 12 is proportional to the length L (see FIG. 5 ) from the connection position of the conductive layer 304 with the second harness 22 to the position where contact with the contact area 200 of the piston 12 begins (R ∝ L), and becomes higher as the length L becomes longer and becomes lower as the length L becomes shorter.

[0043] In this embodiment, since the contact area 200 of the piston 12 is composed of a plurality of conductive portions 201 and a plurality of insulating portions 202, the change in the resistance value R between the air sleeve 13 and the piston 12 is not linear but step-like (see FIG. 6).

[0044] <Vehicle Height Detecting Method> Next, a method for detecting the vehicle height will be described with reference to FIGS. 5 and 6. FIG.

[0045] Fig. 5 is an explanatory diagram illustrating the state of the air spring 1 when the piston 12 operates. Fig. 6 is a graph showing the state of change in the resistance value R over time.

[0046] In FIG. 5, if the state of the piston 12 of the air spring 1 shown in the center is taken as the reference state, the air spring 1 shown on the left is in a state in which the piston 12 is fully contracted, and the air spring 1 shown on the right is in a state in which the piston 12 is fully extended.

[0047] 5, when the piston 12 is in its most retracted state, i.e., when the vehicle height is at its lowest, the length L from the connection position of the conductive layer 304 of the air sleeve 13 with the second harness 22 to the position where contact with the contact area 200 of the piston 12 begins is shorter than the length L when the piston 12 is in the reference state. Therefore, the resistance value R between the air sleeve 13 and the piston 12 is also lower than the resistance value R when the piston 12 is in the reference state.

[0048] 5, when the piston 12 is in the most extended state, i.e., when the vehicle height is at its highest, the length L from the connection position of the conductive layer 304 of the air sleeve 13 with the second harness 22 to the position where contact with the contact area 200 of the piston 12 begins is longer than the length L when the piston 12 is in the reference state. Therefore, the resistance value R between the air sleeve 13 and the piston 12 is also higher than the resistance value R when the piston 12 is in the reference state.

[0049] For example, when the piston 12 strokes at a predetermined speed from its most contracted state (the state shown on the left side of FIG. 5 ) to its most extended state (the state shown on the right side of FIG. 5 ), the resistance R between the air sleeve 13 and the piston 12 gradually increases, as shown in the upper graph of FIG. 6. However, while the conductive layer 304 of the air sleeve 13 passes through each of the multiple insulating portions 202 in the contact area 200 of the piston 12, the resistance R does not change (the portion α in the upper graph of FIG. 6 ).

[0050] Therefore, when conductive layer 304 of air sleeve 13 separates from current-carrying portion 201, resistance R changes, and the slope (differential value), i.e., the change in resistance R over time, is calculated, resulting in a pulse-like waveform as shown in the lower graph of Fig. 6. This pulse is not easily affected by changes in the resistance of the conductive elastic body that forms conductive layer 304 due to external environmental factors (such as temperature).

[0051] The controller X stores in advance the initial position of the piston 12 (reference vehicle height) (reset operation), and counts the number of pulses shown in the graph at the bottom of Fig. 6, i.e., measures the change over time in the resistance value R between the air sleeve 13 and the piston 12, thereby calculating the stroke amount of the piston 12. The controller X then multiplies the number of counted pulses by the distance between adjacent conductive parts 201 (the width dimension in the arrangement direction of the insulating parts 202), thereby determining the stroke position of the piston 12, i.e., the vehicle height, and outputs the result of detection.

[0052] In addition, the controller X may measure the resistance value R from the value of the current flowing in the electrical circuit when a constant voltage is applied between the first harness 21 and the second harness 22, or may measure the resistance value R from the value of the voltage applied between the first harness 21 and the second harness 22 when a constant current is passed through the electrical circuit.

[0053] In this way, by forming conductive layer 304 made of a conductive elastic material in at least the area of ​​air sleeve 13 that contacts contact area 200 of piston 12 out of the area that contacts outer circumferential surface 120 of piston 12, vehicle height can be detected with high accuracy without using a sensor such as a potentiometer, which makes it possible to reduce costs compared to when vehicle height is detected using a sensor such as a potentiometer.

[0054] Furthermore, by defining the area of ​​the piston 12 that is in contact with the conductive layer 304 as the contact area 200 and measuring the change over time in the resistance value R between the air sleeve 13 and the piston 12, even if the resistance value of the conductive elastic body that forms the conductive layer 304 changes due to the external environment, the disturbance toughness in vehicle height detection can be improved, and vehicle height can be detected more accurately.

[0055] In this embodiment, the cross-sectional area of ​​the conductive layer 304 is set to 0.2 cm 2 If the length L when the piston 12 is fully extended and the vehicle height is at its highest (the state shown on the right side of FIG. 5 ) is 20 cm, it is desirable to set the volume resistivity of the conductive layer 304 to about 50 [Ω cm]. By setting the volume resistivity of the conductive layer 304 to about 50 [Ω cm], the vehicle height can be detected with the same level of accuracy as when a conventional sensor such as a potentiometer is used.

[0056] <Modification> Next, an air spring according to a modification of the present invention will be described with reference to Figures 7 to 9. In Figures 7 to 9, components that are common to those described in the above embodiment are given the same reference numerals, and descriptions thereof will be omitted.

[0057] Fig. 7 is a side view showing one side of piston 12A of an air spring according to a modified example of the present invention. Fig. 8 is an external perspective view showing an example of the configuration of air sleeve 13A of an air spring according to a modified example of the present invention. Fig. 9 is a graph showing the change over time in resistance value R in the modified example of the present invention.

[0058] In this modification, as shown in Fig. 7, the contact area 200A of the piston 12A includes a first contact area 210 and a second contact area 220 that are arranged side by side in the circumferential direction of the piston 12A. Note that, although Fig. 7 shows the first contact area 210 on the left side and the second contact area 220 on the right side, there are no particular limitations on the relative positions of the first contact area 210 and the second contact area 220.

[0059] In the first contact region 210, the spacing between the plurality of current-carrying parts 201 becomes narrower toward one side in the stroke direction of the piston 12A (in this modified example, the direction in which the piston 12A contracts). In other words, in the first contact region 210, the spacing between the plurality of current-carrying parts 201 becomes wider toward the other side in the stroke direction of the piston 12A (in this modified example, the direction in which the piston 12A extends).

[0060] On the other hand, in the second contact region 220, the arrangement intervals of the multiple current-carrying parts 201 become wider toward one side in the stroke direction of the piston 12A (in this modified example, the direction in which the piston 12A contracts). In other words, in the second contact region 220, the arrangement intervals of the multiple current-carrying parts 201 become narrower toward the other side in the stroke direction of the piston 12A (in this modified example, the direction in which the piston 12A extends).

[0061] In this modified example, the plurality of current-carrying portions 201 are set to have the same width dimension in the arrangement direction, that is, in the stroke direction (axial direction) of the piston 12A, as in the above embodiment.

[0062] As shown in FIG. 8, the surface of the outer cover layer 301 of the air sleeve 13A is provided with a first conductive layer 304A corresponding to the first contact area 210 of the piston 12A and a second conductive layer 304B corresponding to the second contact area 220 of the piston 12A.

[0063] The first conductive layer 304A and the second conductive layer 304B are arranged apart with a predetermined gap therebetween, and the gap is formed by an insulating elastic body (in this modified example, the outer cover layer 301).

[0064] When the piston 12A strokes at a predetermined speed, the change in resistance R between the air sleeve 13A and the piston 12A over time forms a pulse-like waveform as shown in Fig. 9. At this time, the pulse intervals at the first contact area 210 increase over time, while the pulse intervals at the second contact area 220 decrease over time.

[0065] In this way, in this modified example, the pulse intervals in the first contact area 210 and the second contact area 220 are different, so that the controller X can determine the stroke position of the piston 12A without having to store the initial position of the piston 12 (reference vehicle height) in advance, i.e., without performing a reset operation.

[0066] The above describes the embodiments and modifications of the present invention. Note that the present invention is not limited to the above-described embodiments and modifications, and various other modifications are also included. For example, the above-described embodiments and modifications have been described in detail to clearly explain the present invention, and are not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of this embodiment and modifications with configurations of other embodiments, and it is also possible to add configurations of other embodiments to the configuration of this embodiment and modifications. Furthermore, it is possible to add, delete, or replace part of the configuration of this embodiment and modifications with other configurations.

[0067] For example, in the above embodiment and modified examples, the air sleeve 13, 13A has four layers: the outer cover layer 301, the first reinforcing layer 303A, the second reinforcing layer 303B, and the inner cover layer 302. However, this is not limited to this, and the air sleeve 13, 13A may be composed of, for example, three layers: the outer cover layer 301, the reinforcing layer 303, and the inner cover layer 302.

[0068] Furthermore, in the above embodiment and modified examples, the air spring 1 applied to an automobile has been described as an example, but there are no particular restrictions on the type of vehicle as long as it is an air sleeve for an air spring applied to a vehicle.

[0069] Furthermore, in the above embodiment and modified example, the width dimension of the plurality of current-carrying parts 201 in the arrangement direction is set to be the same, but this is not limited to this.

[0070] 1: Air spring 12, 12A: Piston 13, 13A: Air sleeve 21: First harness 22: Second harness 120: Outer peripheral surface 130A: Outer surface 200, 200A: Contact area 201: Current-carrying portion 202: Insulating portion 210: First contact area 220: Second contact area 301: Outer cover layer 302: Inner cover layer 303, 303A: First reinforcing layer (reinforcing layer) 303, 303B: Second reinforcing layer (reinforcing layer) 304: Conductive layer R: Resistance value

Claims

1. An air spring for a vehicle comprising: a piston that strokes in accordance with the operation of a suspension; and a cylindrical air sleeve having one end connected to the body and the other end connected to the piston, the outer surface of which comes into contact with the outer circumferential surface of the piston when air pressure is applied; wherein the outer circumferential surface of the piston is provided with a contact area in which a plurality of conductive parts and a plurality of insulating parts are arranged alternately adjacent to each other along the stroke direction; and wherein, of the area of ​​the outer surface of the air sleeve that comes into contact with the outer circumferential surface of the piston, at least the area that comes into contact with the contact area is formed of an elastic material having electrical conductivity.

2. An air spring as defined in claim 1, wherein the air sleeve comprises: an outer cover layer having elasticity on the outer surface side; an inner cover layer having elasticity and arranged on the inner circumferential side of the outer cover layer; and reinforcing layers bonded to the inner circumferential surface of the outer cover layer and the outer circumferential surface of the inner cover layer, and an electrically conductive layer formed of an electrically conductive elastic body is bonded to the surface of the outer cover layer in an area that comes into contact with the contact area.

3. An air spring according to claim 1, wherein the plurality of conductive parts have the same width dimension in the arrangement direction and are arranged at equal intervals.

4. An air spring as claimed in claim 1, wherein the plurality of conductive parts have the same width dimension in the arrangement direction, and the contact areas include a first contact area in which the spacing between the plurality of conductive parts becomes narrower towards one side in the stroke direction of the piston, and a second contact area arranged alongside the first contact area in the circumferential direction of the piston, and in which the spacing between the plurality of conductive parts becomes wider towards the one side in the stroke direction of the piston, and wherein the outer surface of the air sleeve is formed such that the areas in contact with the first contact area and the second contact area are each made of a conductive elastic material, and the areas other than the areas in contact with the first contact area and the second contact area are made of an insulating elastic material.

5. A vehicle height detection system for detecting the height of a vehicle, comprising: an air spring according to any one of claims 1 to 4; a first harness electrically connected to the contact area of ​​the piston of the air spring; a second harness electrically connected to a portion of the air sleeve of the air spring formed by the conductive elastic body; and a controller connected to each of the first harness and the second harness, measuring changes over time in resistance value between the air sleeve and the piston, calculating a stroke amount of the piston based on the measured changes over time in resistance value, and detecting the height of the vehicle based on the calculated stroke amount.

6. A vehicle height detection method for detecting the height of a vehicle, comprising: measuring a change over time in resistance value between the air sleeve and the piston of the air spring described in any one of claims 1 to 4; calculating a stroke amount of the piston based on the measured change over time in resistance value; and detecting the height of the vehicle based on the calculated stroke amount.

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