JP2008105633A - Air suspension device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a good anti-rolling effect without requiring rolling rigidity as large as a conventional stabilizer. <P>SOLUTION: This invention relates to an air suspension device suspending right and left positions of an axle 1 on a vehicle body 3 side via an air spring 2. A surge tank 4 supplementing respective capacity is individually connected to right and left air springs 2 via an always-closed flow path open/close means 9. When an extension stroke becomes larger than a predetermined tolerance of any of right and left air springs 2, the flow path open/close means 8 corresponding to the air springs 2 can be opened. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an air suspension device.

  Since the vehicle body is elastically supported from the axle side via the suspension, if a centrifugal force acts on the counter-turning side during turning, the vehicle body side is inertial relative to the axle side that is grounded via the road surface and wheels. In this way, the vehicle is displaced laterally, thereby causing a shift in the center of gravity of the vehicle, and rolling occurs in which the vehicle body tilts counterclockwise.

  For this reason, a stabilizer that twists and deforms due to the occurrence of rolling and suppresses rolling by a restoring force is generally provided. Generally, both ends of a stabilizer bar that forms a U-shape in plan view are connected to the axle side. There is widely known a type in which a central part extending in the vehicle width direction is tiltably connected to the vehicle body side so as to be tiltable.

  That is, in this type of stabilizer, when the left and right wheels move up and down at the same time, the stabilizer bar only tilts left and right evenly with respect to the axle side, but when the left and right wheels make different vertical movements when turning In this case, a torsional moment acts on the stabilizer bar, and the anti-rolling effect of returning the left and right wheels to the original by the reaction force is obtained.

In addition, as the prior art document information of the air spring device related to this application, the following information by the same applicant as the present invention has already been proposed.
JP 2003-194123 A

  However, in the conventional rolling suppression means using such a stabilizer, the anti-rolling effect can be improved only by increasing the roll rigidity (increasing the rigidity of the torsional deformation of the stabilizer bar). When the roll rigidity is increased, the vertical spring constant of the stabilizer is superimposed on the vertical spring constant of the suspension, resulting in a substantial increase in the spring constant.

  For this reason, there is a problem that even if the spring constant of the suspension is lowered to improve riding comfort, if the roll rigidity is increased to suppress rolling, the riding comfort cannot be effectively improved.

  In addition, when the vehicle is a transport vehicle such as a truck, if the roll rigidity required under the constant load condition is given, the roll rigidity is too large under the empty load condition, resulting in poor ride comfort, or grounding on a twisted road surface, etc. There was also a risk of deteriorating the quality (decreased mobility).

  The present invention has been made in view of the above-described circumstances, and an object thereof is to obtain a good anti-rolling effect without requiring a large roll rigidity as in the case of a conventional stabilizer.

  In the air suspension apparatus in which the left and right positions of the axle are suspended on the vehicle body side via air springs, surge tanks that compensate the respective capacities of the left and right air springs are individually connected via normally closed channel opening / closing means. When the extension stroke of either the left or right air spring exceeds a predetermined allowable range, the flow path opening / closing means corresponding to the air spring can be opened.

  Thus, when configured in this way, a centrifugal force acts on the anti-turning side during rolling and rolling occurs, and when the anti-turning side of the vehicle body sinks against the axle and the turning side rises, The extension stroke of the spring becomes larger than the predetermined allowable range, the flow path opening / closing means corresponding to the air spring on the turning side is opened, the capacity on the surge tank side is added to the capacity on the air spring side, and the working air As the total amount increases, the spring constant of the air spring on the turning side decreases.

  As a result, the spring center of the left and right air springs (the position where the resultant force of the left and right air springs acts) moves from the original intermediate position in the vehicle width direction to the anti-turning side. The counter moment arm corresponding to the position deviation of the position is generated, whereby the anti-rolling moment acts and the generation of the rolling moment is remarkably suppressed.

  That is, rolling of the vehicle body during turning means that the vehicle body side is displaced to the anti-turning side due to the inertia due to the centrifugal force, so that the center of gravity of the vehicle is shifted from the original intermediate position in the vehicle width direction to the anti-turning side. This occurs when a gravitational moment that tilts counterclockwise is generated, but if the spring centers of the left and right air springs can be moved further counterclockwise than the position of the center of gravity of the vehicle, this occurs. The gravity moment that acts will act as an anti-rolling moment that reduces the generation of rolling.

  Note that the expansion and contraction of the air spring caused by the input from the general road surface is basically that the thrust when the wheel rides on the step or the convex part is absorbed by the compression of the air spring and returns to the original state. Yes, because the expansion stroke rarely appears greatly during the expansion / contraction operation of the air spring to improve riding comfort during normal driving, set the allowable range of the expansion stroke so that the flow path opening / closing means is opened only during turning It is relatively easy.

  Moreover, even if the actual rolling inclination angle is slight, the turning-side air spring away from the rolling center has a relatively large displacement and an extension stroke appears. As soon as the turning side of the vehicle begins to lift, the extension stroke of the air spring on the turning side exceeds the predetermined allowable range and an anti-rolling effect is obtained, and the function of suppressing the rolling before large rolling occurs in the vehicle body works effectively become.

  Further, when carrying out the present invention more specifically, a surge tank is mounted on the top of the air spring, and a valve body that closes the communication passage communicating between the air spring and the surge tank from the air spring side is provided. The valve body is pulled from the ceiling surface of the surge tank via a tension spring so that the closed state is maintained, and the space between the valve body and the bottom surface of the air spring corresponds to an allowable range of the extension stroke of the air spring. It is good to connect by the string which has the excess of length, and to comprise a flow-path opening-and-closing means with these valve bodies, a tension spring, and a string.

  In this way, when the extension stroke of the air spring becomes larger than the predetermined allowable range on the turning side where the vehicle body is lifted, the valve body is pulled out from the communication passage because the string is extended and the length becomes insufficient. Thus, the closed state is released, and the air spring on the swivel side and the surge tank are opened via the communication passage.

  According to the air suspension device of the present invention described above, various excellent effects as described below can be obtained.

  (I) According to the invention described in claim 1 of the present invention, even if the roll is not forcedly suppressed by giving a large roll rigidity as in the case of a conventional stabilizer, it is caused by the gravitational moment from the initial stage of rolling of the vehicle body. Since a good anti-rolling effect can be obtained by inducing a natural reaction, it is possible to improve the riding comfort by lowering the spring constant of the suspension without any trouble. Particularly, the vehicle is a transport vehicle such as a truck. In some cases, the roll rigidity required under constant loading conditions does not have to be as high as before, so avoiding deterioration in ride comfort and ground contact on twisted road surfaces (decreased mobility) even in empty loading conditions. Can do.

  (II) According to the invention described in claim 1 of the present invention, when rolling occurs at the time of turning and the turning side of the vehicle body begins to lift with respect to the axle, the function of suppressing the rolling immediately starts to be effective, so that significant rolling occurs on the vehicle body. Compared to conventional stabilizers, which can effectively suppress rolling by applying a function to suppress rolling before, and a large anti-rolling force is applied after large rolling occurs in the vehicle body The handling stability at the time can be greatly improved.

  (III) According to the invention described in claim 2 of the present invention, since the flow path opening / closing means can be mechanically opened by utilizing the fact that the turning side of the vehicle body is lifted during turning, a special drive for the operation is provided. No source or electronic control is required, and the cost required to implement it can be greatly reduced.

  Embodiments of the present invention will be described below with reference to the drawings.

  1 and 2 exemplify a case where the air suspension device of this embodiment is applied to the rear side of a large vehicle such as a truck or a bus. In the figure, 1 is a rear axle, and 2 is a left and right side of the axle 1. In the example shown here, a surge tank 4 is mounted on the top of each air spring 2 to compensate for the respective capacity, and the surge tank 4 and the air spring 2 are suspended. Are communicated with each other by a communication passage 5.

  Here, the communication passage 5 is closed by the valve body 6 from the air spring 2 side, and the valve body 6 is pulled from the ceiling surface of the surge tank 4 through the tension spring 7 so as to be kept closed. In addition, the valve body 6 and the bottom surface of the air spring 2 are connected by a string 8 having a surplus length corresponding to the allowable range of the extension stroke of the air spring 2. Yes.

  That is, the valve body 6, the tension spring 7, and the string 8 constitute a flow path opening / closing means 9 that opens the communication path 5 when the extension stroke of the air spring 2 exceeds a predetermined allowable range. It has become.

  Thus, if the air suspension device is configured in this way, for example, when the vehicle turns in the left direction indicated by the arrow A in FIG. 2, the centrifugal force acts in the right direction indicated by the arrow B. As a result, rolling of the inclination angle θ occurs, so that the anti-turning side of the vehicle body 3 sinks with respect to the axle 1 and the turning side rises, and the extension stroke of the air spring 2 on the turning side becomes larger than a predetermined allowable range.

  At this time, when the string 8 is fully extended and the length is insufficient, the valve body 6 is pulled out of the communication passage 5 to release the closed state, and the connection between the air spring 2 on the turning side and the surge tank 4 is connected to the communication passage 5. Therefore, the capacity on the surge tank 4 side is added to the capacity on the air spring 2 side, and the total amount of working air increases, so that the spring constant of the air spring 2 on the turning side decreases.

  As a result, the spring center S of the left and right air springs 2 (the position where the resultant force Fs of the left and right air springs 2 acts) moves from the original intermediate position C in the vehicle width direction to the counter-turning side. A counter moment arm e corresponding to the positional deviation between the center S and the vehicle center of gravity G is generated, whereby the anti-rolling moment acts and the generation of the rolling moment is remarkably suppressed.

  That is, rolling of the vehicle body 3 at the time of turning means that the vehicle body 3 side is displaced to the counter-turning side due to the inertia by the centrifugal force, so that the center of gravity G of the vehicle moves from the intermediate position C in the vehicle width direction to the anti-turning side. This occurs when a gravitational moment is generated that tilts the vehicle body 3 to the counter-turning side, but the spring center S of the left and right air springs 2 is placed further on the counter-turning side than the shift position of the vehicle center of gravity G. If it can be moved, the gravity moment e × W (W: the weight on the vehicle body side acting on the vehicle center of gravity G) generated thereby acts as an anti-rolling moment that reduces the generation of rolling.

  In addition, the expansion / contraction operation of the air spring 2 caused by the input from the general road surface basically means that the thrust when the wheel rides on the step or the convex portion is absorbed by the compression of the air spring 2 and returns to the original state. Since the expansion stroke does not appear greatly in the expansion / contraction operation of the air spring 2 for improving the riding comfort during normal driving, the extension stroke is allowed so that the flow path opening / closing means 9 is opened only during turning. Setting the range by the length of the string 8 is relatively easy.

  Moreover, even if the actual rolling inclination angle θ is slight, the turning air spring 2 away from the rolling center has a relatively large displacement and an extension stroke appears. On the other hand, as soon as the turning side of the vehicle body 3 starts to rise, the extension stroke of the air spring 2 on the turning side exceeds the predetermined allowable range, and the string 8 is fully extended. The closed state is released by being pulled out, the spring constant of the air spring 2 on the turning side is lowered, an anti-rolling effect is obtained, and the function of suppressing the rolling before large rolling occurs in the vehicle body 3 works effectively become.

  Therefore, according to the above embodiment, a natural reaction due to the gravitational moment can be induced from the initial stage of occurrence of rolling of the vehicle body 3 without having to suppress the rolling forcefully by giving a large roll rigidity like a conventional stabilizer. As a result, the anti-rolling effect can be obtained with a lower spring constant of the suspension without difficulty, especially when the vehicle is a transport vehicle such as a truck. Therefore, it is not necessary to increase the roll rigidity required by the conventional method, so that it is possible to avoid deterioration of riding comfort and deterioration of ground contact property (decrease in mobility) even in an empty load condition.

  Furthermore, when rolling occurs during turning and the turning side of the vehicle body 3 begins to float with respect to the axle 1, the function of suppressing rolling immediately starts to work. Therefore, the function of suppressing rolling before large rolling occurs in the vehicle body 3 is effective. The steering stability during turning is greatly improved compared to the case of a conventional stabilizer in which a large anti-rolling force is applied after a large rolling occurs in the vehicle body 3. Can do.

  In particular, when the flow path opening / closing means 9 is constituted by the valve body 6, the tension spring 7 and the string 8 as shown in the drawing, the flow path opening / closing means 9 is mechanically moved by utilizing the fact that the turning side of the vehicle body 3 is lifted during turning. Therefore, no special drive source or electronic control is required for the operation, and the cost required for the operation can be greatly reduced.

  Here, it is further noted that in a large vehicle in which the air suspension device as in the present embodiment is applied to the rear side, the vehicle body 3 side is displaced forward of the vehicle due to inertia relative to the axle 1 side during braking. When the pitching of the rear side 3 is sinking and the rear side is lifted, the flow opening / closing means 9 is opened when the extension stroke of the rear-side air spring 2 exceeds a predetermined allowable range. The spring constant of the air spring 2 on the side decreases and the spring center in the relationship between the front and rear wheels (the position where the resultant force of the front and rear air springs acts) moves to the front side from the original position. By replacing the same principle as in the case of the suppression with the relationship between the left and right wheels and the relationship between the front and rear wheels, an additional effect that pitching during braking can be suppressed is also obtained.

  The air suspension device of the present invention is not limited to the above-described embodiment. The surge tank does not necessarily have to be mounted on the top of the air spring. In addition to the mechanical operation system as shown in the figure, the flow path opening / closing means may be operated by electronic control using an electromagnetic valve or the like. Of course, various changes can be made without departing from the scope of the present invention.

It is the schematic which shows an example of the form which implements this invention. It is a schematic diagram explaining the suppression principle of rolling.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Axle 2 Air spring 3 Car body 4 Surge tank 5 Connection passage 6 Valve body 7 Tension spring 8 String 9 Flow path opening / closing means

Claims (2)

  In an air suspension system in which the left and right positions of the axle are suspended on the vehicle body side via air springs, surge tanks that compensate the respective capacities of the left and right air springs are individually connected via normally closed channel opening / closing means, and either left or right An air suspension device characterized in that when the extension stroke of the air spring becomes larger than a predetermined allowable range, the flow path opening / closing means corresponding to the air spring can be opened.   A surge tank is mounted on the top of the air spring, and a valve body that closes the communication passage communicating between the air spring and the surge tank from the air spring side is provided, and the valve body is provided with a tension spring from the ceiling surface of the surge tank. The valve body and the bottom surface of the air spring are connected by a string having a surplus length corresponding to the allowable range of the extension stroke of the air spring. 2. The air suspension device according to claim 1, wherein the channel opening / closing means is constituted by a body, a tension spring, and a string.

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