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

Abstract

Provided are an air sleeve, a vehicle height detection system, and a vehicle height detection method with which a vehicle height can be accurately detected while cost is reduced.　In a cylindrical air sleeve 13 which constitutes an air spring 1 applied to a vehicle, of which one end is connected to a body side and the other end is connected to a piston 12 stroked with the operation of a suspension, and of which an outer surface 130 comes into contact with an outer peripheral surface 120 serving as a conductor surface of a piston 12 due to the action of air pressure, at least a portion of the outer surface 130 along the stroke direction of the piston 12 in a region in contact with the outer peripheral surface 120 of the piston 12 is formed of an electroconductive elastic body.

Description

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

[0001] The present invention relates to an air sleeve of 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 sleeve, 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 use in a vehicle, the air sleeve having one end connected to the body and the other end connected to a piston that strokes in accordance with the operation of the suspension, and an outer surface of which comes into contact with a conductive surface of the piston when air pressure is applied, characterized in that at least a portion of the outer surface of the air sleeve that comes into contact with the conductive surface along the stroke direction of the piston is formed of an electrically conductive elastic material.

[0008] [2] More preferably, the present invention is an air sleeve as described in [1] above, comprising: 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, wherein a conductive layer formed of an elastic material having conductivity is bonded to at least a portion of the surface of the outer cover layer along the stroke direction of the piston.

[0009] [3] More preferably, the present invention is an air sleeve as described in [1] above, further comprising: 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, wherein the outer cover layer is formed from an electrically conductive elastic material.

[0010] [4] The present invention also provides a vehicle height detection system for detecting the height of a vehicle, comprising: the air sleeve according to any one of claims 1 to 3; the piston; a first harness electrically connected to a portion of the air sleeve formed by the conductive elastic body; a second harness electrically connected to the conductor surface of the piston; and a controller connected to each of the first harness and the second harness, measuring a resistance value between the air sleeve and the piston, and detecting the height of the vehicle in accordance with the measured resistance value based on a correlation between the resistance value and the height of the vehicle.

[0011] [5] The present invention is also characterized in that, in a vehicle height detection method for detecting the height of a vehicle, a resistance value between the air sleeve described in any one of [1] to [3] above and a piston that strokes in accordance with the operation of the suspension is measured, and the vehicle height is detected according to the measured resistance value based on the correlation between the resistance value and the vehicle height.

[0012] 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.

[0013] It is a diagram showing an example of the configuration of an air spring equipped with an air sleeve according to an embodiment of the present invention. It is an external perspective view showing an example of the configuration of an air sleeve. It is a cross-sectional schematic view showing a partial cross section of the air sleeve shown in Figure 2. It is an explanatory diagram explaining the state of the air spring when the piston is actuated. It is a graph showing the correlation between resistance value and vehicle height.

[0014] Hereinafter, an air sleeve for an air spring used in an automobile suspension will be described as an example of one aspect of an air sleeve 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 according to an embodiment of the present invention 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.

[0015] <Overall Configuration of Air Spring 1> First, the overall configuration of the air spring 1 will be described with reference to FIG.

[0016] Fig. 1 is a diagram showing an example of the configuration of an air spring 1 including an air sleeve 13 according to an embodiment of the present invention. In Fig. 1, cross-sectional portions are not hatched in order to make the structure of the air spring 1 easier to see.

[0017] 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.

[0018] 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.

[0019] The outer peripheral surface 120 of the piston 12 is formed as a conductive surface. For example, when the piston 12 is made of iron, the surface is often coated with a non-conductive cationic paint to prevent rust. The conductive surface is then formed by further surface treatment (such as plating) using a conductive material (such as aluminum, iron, or zinc). Furthermore, when the piston 12 is made of conductive aluminum, the conductive surface is formed without surface treatment such as plating.

[0020] In this embodiment, 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.

[0021] The air sleeve 13 has one end in the extension direction fixed to the chamber 11 by crimping the outer surface 130A side with a crimping ring 14A, and the other end in the extension direction fixed to the piston 12 by crimping the inner surface 130B side with a crimping ring 14B.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] In this embodiment, one end of the air sleeve 13 in the extension direction has a conductive portion, and is connected to the second harness 22. 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 portion of the air sleeve 13 and crimps the outer surface 130A side, the second harness 22 may be connected to the crimping ring 14A.

[0026] <Configuration of Air Sleeve 13> Next, the configuration of the air sleeve 13 will be described with reference to FIGS. 2 and 3. FIG.

[0027] Fig. 2 is an external perspective view showing an example of the configuration of the air sleeve 13. Fig. 3 is a schematic cross-sectional view showing a partial cross section of the air sleeve 13 shown in Fig. 2. Note that hatching is not applied to Fig. 3 in order to make the structure of the air sleeve 13 easier to see.

[0028] 2, 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.

[0029] As shown in FIG. 3 , 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.

[0030] 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 3, 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.

[0031] 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.

[0032] In this embodiment, a conductive layer 304 formed 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).

[0033] 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.

[0034] 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.

[0035] 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.

[0036] The conductive layer 304, together with the outer cover layer 301, constitutes the outer surface 130A of the air sleeve 13, and the contact area with the outer peripheral surface 120 of the piston 12 varies according to the stroke of the piston 12.

[0037] The second harness 22 (see FIG. 1) is connected to the end of the conductive layer 304 on the side of the small cylinder portion 31, and 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 area between the conductive layer 304 and the outer circumferential surface 120 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.

[0038] 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 outer surface 120 of the piston 12 begins, and changes in proportion to the stroke of the piston 12.

[0039] 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. 4 ) from the connection position of the conductive layer 304 with the second harness 22 to the position where contact with the outer circumferential surface 120 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.

[0040] <Vehicle Height Detecting Method> Next, a method for detecting the vehicle height will be described with reference to FIGS.

[0041] Fig. 4 is an explanatory diagram illustrating the state of the air spring 1 when the piston 12 operates. Fig. 5 is a graph showing the correlation between the resistance value R and the vehicle height.

[0042] In FIG. 4, 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.

[0043] 4, 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 outer circumferential surface 120 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.

[0044] 4, when the piston 12 is in its 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 outer circumferential surface 120 of the piston 12 begins is longer than the length L when the piston 12 is in the reference state. Therefore, the resistance R between the air sleeve 13 and the piston 12 is also higher than the resistance R when the piston 12 is in the reference state.

[0045] As shown in Fig. 5, the resistance value R is proportional to the vehicle height, and the higher the resistance value R, the higher the vehicle height, and the lower the resistance value R, the lower the vehicle height. For example, the controller X stores in advance the correlation between the resistance value R and the vehicle height shown in Fig. 5, and applies the measured resistance value R to this correlation to determine the vehicle height, which is then output as the detection result.

[0046] 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.

[0047] In this way, by forming conductive layer 304 made of a conductive elastic material on at least a portion of the area of ​​air sleeve 13 that contacts outer circumferential surface 120 of piston 12 along the stroke direction 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.

[0048] 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. 4 ) 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.

[0049] The above describes an embodiment of the present invention. Note that the present invention is not limited to the above embodiment and includes various modifications. For example, the above embodiment has been described in detail to clearly explain the present invention, and is not necessarily limited to an embodiment including all of the described configurations. Furthermore, it is possible to replace part of the configuration of this embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of this embodiment. Furthermore, it is also possible to add, delete, or replace part of the configuration of this embodiment with other configurations.

[0050] For example, in the above embodiment, the outer cover layer 301 is made of an insulating elastic material (rubber), and the conductive layer 304 formed of an elastic material having conductivity is bonded to a part of the surface of the outer cover layer 301 along the stroke direction of the piston 12. However, this is not limited to this, and for example, the outer cover layer 301 may be formed of an elastic material having conductivity.

[0051] In addition, in the above embodiment, the air sleeve 13 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 may be composed of, for example, three layers: the outer cover layer 301, the reinforcing layer 303, and the inner cover layer 302.

[0052] Furthermore, in the above embodiment, the air sleeve 13 of 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 of an air spring applied to a vehicle.

[0053] 1: Air spring 12: Piston 13: Air sleeve 21: First harness 22: Second harness 120: Outer surface (conductor surface) 130A: Outer surface 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 X: Controller

Claims

1. A cylindrical air sleeve that constitutes an air spring used in a vehicle, one end of which is connected to the body and the other end of which is connected to a piston that strokes in accordance with the operation of the suspension, and whose outer surface comes into contact with the conductive surface of the piston when air pressure is applied, wherein at least a portion of the outer surface along the stroke direction of the piston within the area that comes into contact with the conductive surface is formed from a conductive elastic body.

2. An air sleeve as claimed in claim 1, comprising: an elastic outer cover layer on the outer surface side; an elastic inner cover layer arranged on the inner periphery of the outer cover layer; and reinforcing layers bonded to the inner periphery of the outer cover layer and the outer periphery of the inner cover layer, wherein a conductive layer made of an elastic material having conductivity is bonded to at least a portion of the surface of the outer cover layer along the stroke direction of the piston.

3. An air sleeve as described in claim 1, comprising: an outer cover layer having elasticity on the outer surface side; an inner cover layer having elasticity arranged on the inner peripheral side of the outer cover layer; and reinforcing layers joined to the inner peripheral surface of the outer cover layer and the outer peripheral surface of the inner cover layer, wherein the outer cover layer is formed from an elastic material having electrical conductivity.

4. A vehicle height detection system for detecting the height of a vehicle, comprising: the air sleeve according to any one of claims 1 to 3; the piston; a first harness electrically connected to the conductive surface of the piston; a second harness electrically connected to a portion of the air sleeve formed by the conductive elastic body; and a controller connected to each of the first harness and the second harness, measuring a resistance value between the air sleeve and the piston, and detecting the height of the vehicle in accordance with the measured resistance value based on the correlation between the resistance value and the height of the vehicle.

5. A vehicle height detection method for detecting the height of a vehicle, comprising: measuring a resistance value between the air sleeve described in any one of claims 1 to 3 and the piston; and detecting the vehicle height corresponding to the measured resistance value based on the correlation between the resistance value and the vehicle height.

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