JP2009154547A - Air spring type suspension and spring constant switch control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an air spring type suspension and a spring constant switch control method capable of switching a spring constant without changing a vehicle height during traveling. <P>SOLUTION: The air spring type suspension comprises: an air spring (1) equipped with two air chambers (first air chamber C1, second air chamber C2) with different internal pressures, wherein at least the air chamber (C1) with the lower internal pressure has flexibility; a compressed air supply source (6) for supplying compressed air to the two air chambers (C1, C2); compressed air supply lines (L1, L2) for individually communicating the compressed air supply source (6) and the two air chambers (C1, C2); a channel switch valve (7) interposed in the compressed air supply line (L2); and a control means (control unit 10). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a spring constant variable air spring suspension and a spring constant switching control method.

For example, in a sightseeing bus, a vehicle equipped with an air spring type suspension device has been widely used for the purpose of improving the ride comfort of passengers and passengers and getting on and off.
For example, in a large lorry, an air spring type suspension device is becoming widespread as a driver's labor load reduction and a load pain countermeasure.

  Many sightseeing buses and trucks equipped with an air spring suspension are configured so that the vehicle height can be adjusted in order to improve ease of boarding and unloading and cargo handling. However, the vehicle height adjustment function is also regulated so that it cannot be operated during traveling for safety reasons.

FIG. 6 shows a cross section of an air spring for a prior art suspension system.
In FIG. 6, the entire air spring denoted by reference numeral 1 </ b> J includes a flexible airbag 11 and a cylindrical piston 17 connected to the bottom of the airbag 11.
The cylindrical piston 17 has an opening 17a formed on a part of its upper surface, and the bottom 17b is closed.
That is, in the air spring 1J, the air chamber C17 formed by the cylindrical piston 17 and the air chamber C11 formed by the airbag communicate with each other to form one continuous space C.

In FIG. 6, if the spring constant of the air spring is k, the volume of the continuous space C is Vc, the effective cross-sectional area of the airbag 11 is S, and the air pressure charged in the air spring 1J is p, the spring constant of the air spring. k is represented by the following equation.
k = p × S / Vc

Here, in order to change the spring constant, the capacity Vc of the continuous space C may be changed. Specifically, for example, when it is desired to increase the current spring constant, a part of the air in the continuous space C is exhausted from the air supply / exhaust port 11c using a leveling mechanism (not shown), and the upper end portion of the airbag 11 is exhausted. The height H from 11a to the lower end 17b of the piston 17 may be lowered.
Then, the volume of the air chamber C17 formed by the cylindrical piston 17 does not change, but the volume of the air chamber C11 formed by the airbag decreases and the volume Vc of the continuous space C also decreases.
As a result, the spring constant k of the air spring increases according to the above equation.

  That is, in the air spring 1J configured as shown in FIG. 6, in order to change the spring constant of the air spring, the height H from the upper end portion 11a of the airbag 11 to the lower end 17b of the piston 17 must be changed. .

For sightseeing buses and lorries equipped with air spring suspensions, for example, if you want to run on rough roads with numerous irregularities, you may want to lower the spring constant during driving to improve riding comfort, or There is a demand to prevent damage to the cargo.
Alternatively, in places where the road surface is greatly undulating, it is desirable to increase the spring constant to prevent the platform from swinging.

  However, as described above, since the vehicle height adjustment is prohibited during traveling, such a request cannot be met.

As another conventional technique, a technique using an air spring as a bump stopper has been proposed (see Patent Document 1).
However, the related art is intended to alleviate the impact caused by the thrust with the air spring as a bump stopper when a large thrust acts on the suspension device, and does not solve the above-described problems. Absent.
JP 2004-338642 A

  The present invention has been proposed in view of the above-described problems of the prior art, and an air spring type suspension device and a spring constant switching control method capable of switching a spring constant without changing the vehicle height during traveling. The purpose is to provide.

The air spring suspension of the present invention includes two air chambers (first air chamber C1 and second air chamber C2) having different internal pressures, and at least the air chamber (C1) on the side having a low internal pressure is flexible. An air spring (1), a compressed air supply source (6) for supplying compressed air to the two air chambers (C1, C2), a compressed air supply source (6) and two air chambers Compressed air supply lines (L1, L2) individually communicating with (C1, C2), a flow path switching valve (solenoid valve 7) interposed in the compressed air supply line (L2), and control means (control Unit 10), and the air spring (1) reduces the volume of the air chamber (C1) on the low internal pressure side by filling the air chamber (C2) on the high internal pressure side with compressed air. , Compressed air is removed from the air chamber (C2) on the high internal pressure The control means (10) switches the flow path of the flow path switching valve (7) to increase the volume of the air chamber (C1) on the low internal pressure side. The air chamber (C2) is controlled to communicate with either the compressed air supply source (6) or the atmosphere side (Claim 1).
Here, a spring constant switching means (spring constant switching switch 20) is provided, and by operating the spring constant switching means (20), the control means (10) causes the flow path of the flow path switching valve (7) to flow. It is preferable that the air chamber (C2) on the higher internal pressure side is communicated with either the compressed air supply source (6) or the atmosphere side by switching.

  In the present invention, a cylindrical member (13) is fixed to the bottom of the air chamber (C1) on the low internal pressure side so as to penetrate (partly above), and the cylindrical member (13) It is preferable that a part of the upper end is opened (13a), and an air chamber (C2: air bag 12) on the side where the internal pressure is high is formed below the inside of the cylindrical member (13). .

  In the present invention, it is preferable that a decompression means (8) is interposed in the compressed air supply line (L1) (Claim 3).

  The control method of the air spring type suspension device of the present invention is the spring constant switching control method using the air spring type suspension device according to claim 1, wherein the spring of the air spring (1) is controlled by the spring constant switching means (spring constant switching switch 20). When the high spring constant is selected in the step (S2) of selecting the constant level and the step (S2) of selecting the level of the spring constant, the air chamber on the side where the internal pressure is high by the flow path switching valve (solenoid valve 7) (C2) communicating with the compressed air supply source side (6) (S3), and when a low spring constant is selected, the air chamber (C2) on the higher internal pressure side is moved to the atmosphere side by the flow path switching valve (7). A step (S3) of communicating with (6) (Claim 4).

According to the present invention having the above-described configuration, the air spring (1) is filled with compressed air in the air chamber (C2) on the high internal pressure side, whereby the volume of the air chamber (C1) on the low internal pressure side is filled. And the volume of the air chamber (C1) on the low internal pressure side is increased by removing compressed air from the inside of the air chamber (C2) on the high internal pressure side.
For example, when the driver operates the spring constant switching means (20), the control means (10) causes the flow path of the flow path switching valve (solenoid valve 7) to pass through the air chamber (C2 on the higher internal pressure side). ) In communication with the compressed air supply source (6) or the air chamber (C2) on the higher internal pressure side can be switched to the atmosphere side.

If the air chamber (C2) on the higher internal pressure side is connected to the compressed air supply source (6) in the flow path of the flow path switching valve (solenoid valve 7), the air chamber (C1 on the lower internal pressure side) ) Can be reduced to increase the spring constant of the air spring (1).
Further, if the flow path of the flow path switching valve (7) is made to communicate with the air chamber (C2) on the high internal pressure side to the atmosphere side, the volume of the air chamber (C1) on the low internal pressure side increases. Thus, the spring constant of the air spring (1) can be lowered.

  These spring constant switching controls are not accompanied by a change in the vehicle height, and can therefore be executed even during traveling.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
First, a first embodiment will be described with reference to FIGS.

  In FIG. 1, an air spring type suspension device denoted by reference numeral 100 as a whole in FIG. 1 has four air springs 1 per shaft (two of which are not visible overlapping with the illustrated air spring) in the illustrated example. , A compressed air supply source 6, two compressed air supply lines L1, L2, a flow path switching valve (solenoid valve) 7, a spring constant switching switch 20 serving as a spring constant switching means, and a control unit serving as a control means. 10, and so on.

  The four air springs 1 have two lower ends of a pair of air springs 1 attached to the upper surfaces of both end portions of the air spring support member 2. The upper ends of the two air springs 1 are fixed to the lower surfaces of the left and right side rails 5 of the chassis frame by fastening means (not shown). In FIG. 1, reference numeral 4 denotes a wheel.

  The upper surface of the central portion of the air spring support member 2 is fixed to the lower surface of the axle 3 by a fixing member (not shown).

The detailed configuration and operation of the air spring 1 will be described with reference to FIGS.
In FIG. 2, the air spring 1 has a flexible first airbag 11 and a flexible second airbag 12. The upper portion of the cylindrical member 13 is attached to the bottom portion 11 b of the first airbag 11 so as to partially penetrate (bite into) the first airbag 11.
An air supply / exhaust port 11 c is formed on the upper surface 11 a of the first airbag 11.

An opening 13 a is formed on the upper surface of the cylindrical member 13. The bottom 13b of the cylindrical member 13 is closed.
A second airbag 12 is accommodated inside the cylindrical member 13. The bottom portion 12 b of the second air chamber 12 is fixed to the bottom portion 13 b of the cylindrical member 13.

  An air supply / exhaust port 12 c is formed in the bottom portion 12 b of the second airbag, and the air supply / exhaust port 12 c passes through the bottom portion 13 b of the cylindrical member 13.

  Here, a continuous space formed by a region excluding the first airbag 11 and the second airbag 12 inside the cylindrical body 13 communicating with the first airbag 11 is defined as the first air chamber C1. To tell. The inside of the second airbag 12 is referred to as a second air chamber C2.

Returning to FIG. 1, the first airbag 11 communicates with the air tank 6 through the first compressed air supply line L1.
The first compressed air supply line L1 includes a compressed air supply pipe L11 and branch pipes L12 and L13. The compressed air supply pipe L11 is branched into branch pipes L12 and L13 at a branch point B1 which is one end of the compressed air supply pipe L11. The compressed air supply pipe L11 is provided with a decompressor 8 that is a pressure adjusting means for decompressing the air pressure in the air tank 6.

  The branch pipe L12 is connected to the supply / exhaust port 11c of the left first airbag in FIG. The branch pipe L13 is connected to the supply / exhaust port 11c of the first airbag on the right side in FIG.

The second airbag 12 communicates with the air tank 6 through the second compressed air supply line L2.
The second compressed air supply line L2 includes compressed air supply pipes L20 and L21 and branch pipes L22 and L23. The compressed air supply pipe L21 is branched into branch pipes L22 and L23 at a branch point B2 which is one end of the compressed air supply pipe L21.

A flow path switching valve (solenoid valve) 7 is interposed between the compressed air supply pipe L20 and the compressed air supply pipe L21.
In the illustrated example, the flow path switching valve 7 is a “3-port, 2-position” switching valve. Ports P1, P2, and P3 are formed at a position 71 of the flow path switching valve 7. The ports P1 and P2 are in communication. Ports P4, P5, and P6 are formed at a position 72 of the flow path switching valve 7. Ports P5 and P6 are in communication. The port P6 is always open to the atmosphere.

  The spring constant changeover switch 20 is connected to the control unit 10 by a signal line Ls1. The control unit 10 is connected to the operation unit 73 of the flow path switching valve 7 by a control signal line Ls2. The operation unit 73 is configured to switch between the position 71 and the position 72 when a control signal is input to the operation unit 73.

  FIG. 2 shows a state in which the spring constant of the air spring 1 is increased. At this time, the position 71 of the flow path switching valve 7 is connected to the second compressed air supply line L2 (state shown in FIG. 1). That is, the air tank 6 passes through the compressed air supply pipe L20, the ports P1 and P2 of the flow path switching valve 7, the compressed air supply pipe L21, the branch pipes L22 and L23, and the second airbag of the two air springs 1. 12 communicates. Accordingly, the second air chamber C2 is filled with air having the same pressure as that in the air tank 6.

On the other hand, the first airbag 11 of the two air springs 1 is always in communication with the air tank 6 via the first compressed air supply line L1. However, a decompressor 8 is interposed in the first compressed air supply line L1 (L11), and compressed air having a pressure somewhat lower than the pressure in the air tank 6 is stored in the first air chamber C1. Filled.
That is, the internal pressure of the second air chamber C2 is higher than that of the first air chamber 11. Accordingly, the second airbag 12 is inflated, and as a result, the volume of the first air chamber C1 is reduced.
As described in the prior art of FIG. 6, the volume of the first air chamber C1 is reduced before the volume of the first air chamber C1 is decreased (see, for example, FIG. 3). The constant is increased.

  FIG. 3 shows a state where the spring constant of the air spring 1 is lowered. At this time, the position 72 of the flow path switching valve 7 is connected to the second compressed air supply line L2 (not shown). That is, the air tank 6 communicates with the compressed air supply pipe L20 and the port P4 of the flow path switching valve 7. However, since the inside of the port P4 is closed, the compressed air in the air tank does not flow into the second air chamber C2. Since the second air chamber C2 is opened to the atmosphere via the ports P5 and P6 of the flow path switching valve 7, the air in the second air chamber C2 is discharged to the atmosphere.

On the other hand, the first air chambers C1 of the two air springs 1 are always in communication with the air tank 6 via the first compressed air supply line L1. Therefore, the internal pressure of the first air chamber C1 exceeds the internal pressure (equal to atmospheric pressure) of the second air chamber C2, and as a result, the second air formed by the flexible member (second air bag). Chamber C2 contracts.
Due to the contraction of the second airbag 12, the volume of the first air chamber C1 increases.
The increase in the volume of the first air chamber C1 is a state in which the spring constant of the air spring 1 is lower than that in FIG. 2, as described in the prior art of FIG.

The state in which the spring constant in FIG. 2 is increased and the state in which the spring constant in FIG. 3 is decreased are both performed with the height H of the air spring being equal.
That is, in the first embodiment, the spring constant of the air spring can be switched without adjusting the vehicle height.

  Next, a spring constant switching control method of the air spring suspension 100 according to the first embodiment will be described based on FIG. 4 and also with reference to FIGS.

In FIG. 4, the control unit 10 determines whether or not the spring constant changeover switch 20 has been operated (step S1).
If the spring constant changeover switch 10 is operated (YES in step S1), the process proceeds to step S2. If the spring constant changeover switch 10 is not operated (NO in step S1), step S1 is repeated.

In step S2, the control unit 10 determines whether a higher spring constant is selected or a lower spring constant is selected.
If the higher spring constant is selected, the process proceeds to a loop on the step S3 side, and if the lower spring constant is selected, the process proceeds to a loop on the step S4 side.

In step S3, the control unit 10 switches the flow path switching valve (solenoid valve) 7 so as to communicate with the air tank 6 side.
That is, the position 71 is switched so as to communicate with the second compressed air supply line L2. Then, the volume of the second air chamber C2 increases, the volume of the first air chamber C1 decreases, and the spring constant of the air spring 1 increases. Then, after step S3, the process proceeds to step S5.

In step S4, the control unit 10 switches the solenoid valve 7 to communicate with the atmosphere opening side.
That is, the position 72 is switched so as to communicate with the second compressed air supply line L2. Then, the compressed air in the second air chamber C2 is discharged to the atmosphere, and the volume of the second air chamber C2 decreases. As the volume of the second air chamber C2 decreases, the volume of the first air chamber C1 increases and the spring constant of the air spring 1 decreases. Then, after step S4, the process proceeds to step S5.

  In step S5, the control unit 10 determines whether or not to end the operation. If the operation is to be terminated (YES in step S5), the control is terminated as it is. If the operation is to be continued (NO in step S5), the process returns to step S1, and step S1 and subsequent steps are repeated.

According to 1st Embodiment of the structure mentioned above, the air spring 1 is the 1st air chamber C1 formed with the flexible 1st airbag 11, and the flexible 2nd airbag 12. As shown in FIG. The second air chamber C2 is formed. By filling the second air chamber C2 with compressed air having an internal pressure higher than that of the first air chamber C1, the first air chamber C1 The volume of the first air chamber C1 is increased by reducing the volume and removing the compressed air from the second air chamber C2.
According to the first embodiment, when the driver operates the spring constant changeover switch 20, the control unit 10 causes the flow path of the flow path switching valve (solenoid valve) 7, and the second air chamber C 2 to the air tank 6. Or the second air chamber C2 can be switched to the atmosphere side.

If the flow path of the flow path switching valve (solenoid valve) 7 is made to communicate the second air chamber C2 with the air tank 6, the volume of the first air chamber C1 is reduced, and the spring constant of the air spring 1 is reduced. Can be raised.
On the other hand, if the flow path of the flow path switching valve (solenoid valve) 7 is made to communicate the second air chamber C2 to the atmosphere side, the volume of the first air chamber C1 increases and the air spring 1 The spring constant can be lowered.
These spring constant switching controls are not accompanied by a change in the vehicle height, and can therefore be executed even during traveling.

Next, a second embodiment will be described with reference to FIG.
1 to 4 is an embodiment in which a flexible airbag (second airbag) 12 is accommodated in a cylindrical member 13.
On the other hand, in the air spring 1A of the second embodiment in FIG. 5, the cylindrical member (corresponding to the reference numeral 13 in FIG. 2) is the cylinder 14, and instead of the second airbag 12 in the first embodiment, In this embodiment, a disk-like piston 15 is inserted into the cylinder 14.

  In FIG. 5, the space above the piston 15 is the first air chamber C1, and the space below the piston 15 is the second air chamber C2. The air supply / exhaust port 14 c of the second air chamber is provided in the bottom portion 14 b of the cylinder 14.

  In 2nd Embodiment, except the structure mentioned above, it is substantially the same as 1st Embodiment of FIGS. 1-4. The operational effects of the second embodiment are also substantially the same as those of the first embodiment.

  The illustrated embodiment or example is an exemplification, and is not a description for limiting the technical scope of the present invention.

The block diagram which shows the whole structure of embodiment of this invention. The air spring of 1st Embodiment WHEREIN: The state figure at the time of making a spring constant high. In the air spring of a 1st embodiment, a state figure at the time of making a spring constant low. The flowchart explaining the spring constant switching control of embodiment of this invention. Sectional drawing which showed the structure of the air spring of 2nd Embodiment. Sectional drawing which showed the structure of the prior art air spring.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Air spring / Air spring 2 ... Air spring support member 3 ... Axle 4 ... Wheel 5 ... Side rail of chassis frame 6 ... Compressed air supply source / air tank 7 ... Flow path switching valve / solenoid valve 8 ... Pressure reducing means / pressure reducing device 10 ... Control means / control unit 20 ... Spring constant switching means / spring constant switching switch

Claims (4)

  An air spring having two air chambers having different internal pressures and at least a low air pressure side air chamber having flexibility, a compressed air supply source for supplying compressed air to the two air chambers, and the compression A compressed air supply line that individually communicates the air supply source and the two air chambers; a flow path switching valve that is interposed in the compressed air supply line; and a control means, wherein the air spring has a high internal pressure. The volume of the air chamber on the side with the low internal pressure is reduced by filling the air chamber on the side with the compressed air, and the volume of the air chamber on the side with the low internal pressure is eliminated by removing the compressed air from the air chamber on the side with the high internal pressure. The control means is configured to increase the volume, and the control means switches the flow path of the flow path switching valve so that the air chamber on the high internal pressure side communicates with either the compressed air supply source or the atmosphere side. Specially configured to do Air spring suspension system according to.   The bottom of the air chamber on the low internal pressure side is fixed so as to partially penetrate the upper part of the cylindrical member whose upper end is opened, and the internal pressure is high below the inner side of the cylindrical member. The air spring suspension according to claim 1, wherein a side air chamber is formed.   The air spring suspension according to any one of claims 1 and 2, wherein a decompression means is interposed in the compressed air supply line.   In the spring constant switching control method using the air spring type suspension system according to claim 1, a high spring constant is obtained in the step of selecting the level of the spring constant of the air spring by the spring constant switching means and the step of selecting the level of the spring constant. When selected, a flow switching valve is used when a low spring constant is selected in the step of communicating the air chamber having a higher internal pressure to the compressed air supply source side by the flow switching valve and the step of selecting the level of the spring constant. And a step of causing the air chamber having a higher internal pressure to communicate with the atmosphere side.

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