JPH0672703U - Air suspension sub-tank structure - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] The spring constant is made smaller than before to ensure a good ride comfort, and the spring constant is increased near the full bottom to charge the sub tank after air discharge. Provide a sub-tank structure of an air suspension that shortens the running time and speeds up the running time again. [Structure] A sub-tank body 3 of a sub-tank 2 connected to an air spring 1 is partitioned by a diaphragm 4, and a spring 5 is housed in a sub-tank compartment 10 that does not communicate with the air spring 1 side. To keep the spring constant small.
Further, in the vicinity of the full bottom, the spring 5 is fully compressed to suppress the volume expansion of the sub tank compartment 9 and increase the spring constant to prevent the full bottom. [Effect] It is possible to improve the riding comfort of the vehicle when the vehicle is empty or loaded, prevent the occurrence of a full bottom, and shorten the charging time after the air is discharged to reduce the vehicle height.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a sub-tank structure used for an air suspension of a vehicle, and more particularly, to a sub-tank structure of an air suspension that can improve ride comfort by changing an air volume as an air spring expands and contracts.

[0002]

[Prior art]

 Air suspension has been conventionally used for the suspension mechanism that suspends the axle on the vehicle body side in order to improve riding comfort. There are various types of this air suspension, but as shown in FIGS. 11 and 12, there are some that employ a sub tank 20 that communicates with the air spring 1 and its air chamber 1a. In order to improve the ride comfort of the vehicle, it is desirable to lower the spring constant. However, if the spring constant is too low, the air spring will easily become completely compressed as shown in Fig. 12, and a so-called full bottom will occur, resulting in a comfortable ride. Getting worse. In the case of the air suspension having the sub tank 20, the spring constant is determined by the volume of the air chamber 1a of the air spring 1 and the volume of the sub tank 20. That is, when the volume of the air chamber 1a is constant, if the volume of the sub-tank 20 is small, the rate of volume change of air with respect to the stroke of the air spring 1 is large, and the spring constant is large. Conversely, if the volume is large, Get smaller. However, the rate of change of the spring constant is almost constant for a sub-tank with a fixed volume, so if the sub-tank volume is set so as to ensure a spring constant that does not bottom up during loading, the sub-tank volume will be relatively small and the empty tank There is a problem that the spring constant becomes large and the center of gravity becomes poor. The publicly known techniques effective in solving this problem are Japanese Utility Model Laid-Open No. 60-134015 and Japanese Utility Model Laid-Open No. 59-180908.

The "air suspension device" of Japanese Utility Model Laid-Open No. 60-134015 discloses a capacity inside a surge tank (corresponding to a sub tank) connected to an air spring or between an air spring and a surge tank or between a plurality of surge tanks. A switching valve is provided and a small area communicating portion is formed on the valve. The volume change valve is operated by the pressure change in the air spring caused by the vehicle turning or the compression of the air spring, and the air volume between the air spring and the surge tank is changed to adjust the spring constant and ensure a good ride comfort. It was done. The "vehicle height adjusting device" of Japanese Utility Model Laid-Open No. 59-180908 connects a suspension having an air spring and an external air source via a sub valve and a main valve, and switches to a pipeline between the sub valve and the main valve. It is composed of multiple air tanks (corresponding to sub tanks) connected via valves. The suspension and air tank are selectively connected via a sub valve and a switching valve to adjust the spring constant to ensure a good riding comfort and to introduce air from an external air source for vehicle height adjustment. Even at times, the suspension and the air tank are selectively communicated with each other to optimize the spring constant and ensure a good riding comfort.

[0004]

[Problems to be solved by the device]

 As shown in FIG. 13, when the load (P) is taken on the horizontal axis and the deflection (δ) is taken on the vertical axis, P and δ are obtained in the conventional air suspension sub-tank structure shown in FIGS. 11 and 12. The relationship of is determined by the size of the sub tank 20. That is, when the sub-tank 20 is large, the change of δ with respect to P is large as shown by the curve C, and when the sub-tank 20 is small, the change of δ with respect to P is small as shown by the curve D. Therefore, when the volume of the sub-tank 20 is constant, it is difficult to form an air suspension having a low spring constant with good riding comfort while preventing full bottom.

On the other hand, in the “air suspension device” of Japanese Utility Model Laid-Open No. 60-134015, it is possible to improve the riding comfort by changing the capacity of the surge tank by the volume switching valve, but the surge tank by the capacity switching valve. The surge tank volume does not change according to the stroke of the air spring simply by fully opening or closing, and the selection range is narrow. In addition, a control mechanism for an actuator for controlling the capacity switching valve is required (the contents of which are not described in the publication), and there is a problem that the device structure becomes complicated.

Further, in the case of the "vehicle height adjusting device" of Japanese Utility Model Laid-Open No. 59-180908, the air tank itself is not divided, and a plurality of air tanks are selected by a sub valve and a switching valve. Since the volume is variable, the whole structure becomes large, and the valve control mechanism becomes complicated and expensive.

The present invention solves the above problems and improves the riding comfort by reducing the spring constant during emptying and loading, while increasing the spring constant on the full bottom side to prevent the occurrence of full bottom. However, it is an object of the present invention to provide a sub-tank structure of an air suspension that has a simple structure and that can quickly charge air even when the air inside the sub-tank is discharged to reduce the vehicle height.

[0008]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention provides a diaphragm for defining a closed sub-tank body in a sub-tank structure in which an axle is connected to an air chamber of an air spring for suspending the axle on the vehicle body side, and the diaphragm is used for the air chamber. The sub-tank structure of the air suspension is configured by providing a biasing means for biasing the side. Further, more specifically, it is characterized by a sub-tank structure of an air suspension capable of detachably storing the diaphragm and the biasing means in the sub-tank body.

[0009]

[Action]

 Since the diaphragm is pressed to the air spring side by the spring inside the sub tank body, the sub tank compartment on the air spring side is kept at a small capacity during normal traveling. The stroke of the air spring increases the air pressure in the air spring and the sub-tank compartment, so that the diaphragm presses the spring and the volume of the sub-tank compartment is expanded. This process occurs for both empty and loaded vehicles. Therefore, the spring constant can be kept low compared to the prior art in which the volume of the sub tank is unchanged. Further, since the volume of the sub-tank compartment changes substantially in proportion to the stroke of the air spring, the spring constant can be changed more smoothly and the riding comfort can be improved as compared with the above-mentioned known technique. During the stroke of the air spring close to full bottom, the spring is almost fully compressed, and thereafter the volume of the sub tank does not change. Therefore, in the vicinity of the full bottom, the spring constant rises more rapidly than in other stroke positions, and as a result, the full bottom can be prevented. Furthermore, since the sub-tank body is divided by the diaphragm, the sub-tank compartment has a small volume when the vehicle is empty, and the vehicle height can be lowered so that the air in the compartment can be quickly charged to restore the original state. You can recover in a short time.

[0010]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an overall configuration diagram of the present embodiment, FIG. 2 is an enlarged axial sectional view showing a detailed structure of a sub tank, and FIGS. 3 to 5 show changes in the sub tank due to the stroke of an air spring when the vehicle is empty. 6 to 8 are explanatory axial sectional views showing a change state in the sub-tank due to the stroke of the air spring during loading, and FIG. 9 is a sectional view of the prior art having this embodiment and a sub-tank of a constant volume. FIG. 10 is a diagram showing the relationship between the stroke (S) of the air spring and the spring constant (k). FIG. 10 shows the relationship between the load (P) and the flexure (δ) of the air spring according to the present embodiment using the spring constant as a parameter. It is a diagram showing.

As shown in FIG. 1, an air spring 1 and a leaf spring 16 are mounted on the left and right of an axle 15 of a vehicle, and these are connected to a frame 17 of the vehicle. The air spring 1 is a publicly known one that includes an air chamber 1a and a pressing portion 1b mounted on the axle 15 to compress the air chamber 1a. A sub tank 2 is connected to the air spring 1 via an air pipe 7. Further, a switching valve 12 is connected to the sub tank 2 via an air pipe 8, and a main tank 13 is connected to the switching valve 12. A leveling valve 14 (L / V) is engaged with the switching valve 12. The leveling valve 14 controls the switching of the switching valve 12 by the stroke of the axle 15 (detailed structure, mounting structure omitted).

As shown in FIG. 2, the sub-tank 2 is composed of a sub-tank main body 3, a diaphragm 4 partitioning the sub-tank main body 3 in the middle, a spring 5 as one of biasing means, and the like. The sub tank main body 3 is composed of a case main body 3a and a lid 3b, and the lid 3b is detachably connected to the case main body 3a by bolts 6 or the like to close the rear opening. An air pipe 7 connected to the air spring 1 side and an air pipe 8 connected to the switching valve 12 side are connected to the side of the case body 3a opposite to the opening. In this embodiment, the diaphragm 4 is arranged substantially in the middle of the case main body 3a, and its base end is detachably and movably connected to the case main body 3a by a bolt 11 or the like. Also, the diaphragm 4 is formed of a stretchable and bent shape. The spring 5 abuts on one end side of the diaphragm 4 and abuts on the other end side of the lid 3b so as to be interposed therebetween. The spring 5 presses the diaphragm 4 toward the air tubes 7 and 8. With the above configuration, the sub tank main body 3 is divided into two sub tank division chambers 9 and 10 with the diaphragm 4 as a boundary. The sub-tank compartment 9 forms an air chamber, and the sub-tank compartment 10 serves as a spring storage chamber.

With the above structure, when the axle 15 strokes, the air in the air chamber 1a of the air spring 1 and the sub-tank compartment 9 is compressed via the pressing portion 1b and acts as an appropriate air cushion of the spring constant. The change in vehicle height due to the stroke of the axle 15 is detected by the leveling valve 14, and is adjusted so as to maintain a constant vehicle height by the compressed air introduced from the main tank 13 via the switching valve 12.

Next, the operation of this embodiment will be described with reference to FIGS. 3 to 5 (when empty) and FIGS. 6 to 8 (when loaded). FIG. 3 shows the state of the air spring 1 and the sub tank 2 in a normal running state. During normal traveling, the stroke of the air spring 1 is small, the air pressure in the air chamber 1a and the sub-tank compartment 9 is low, the spring 4 pushes the diaphragm 4, and the sub-tank compartment 9 maintains a small capacity. Therefore, since the combined air volume of the air chamber 1a and the sub tank compartment 9 is small, the spring constant is almost the same as that of the conventional sub tank 20 having the same volume as the sub tank compartment 9 in this state. . Next, when the vehicle bumps onto the convex portion of the ground, the pressing portion 1b strongly presses the air chamber 1a as shown in FIG. 4, but the spring 5 instantaneously raises the air pressure to cause the spring 5 to cover the lid 3b. Is pushed to the side, the diaphragm 4 is pushed to the lid 3b side accordingly, and the volume of the sub tank compartment 9 is expanded. As a result, the spring constant during bumping can be kept low. Further, as shown in FIG. 5, when a stroke close to the full bottom occurs, the air chamber 1a is pressed and the pressure increases, but the spring 5 is further compressed and the diaphragm 4 is pressed toward the lid 3b side, and the sub tank partition is formed. The volume of the chamber 9 is further expanded. Due to the above, the sudden increase in the spring constant is alleviated even at a stroke close to full bottom.

6 to 8 show the state during loading, FIG. 6 shows the state during normal traveling, FIG. 7 shows the state during bumping, and FIG. 8 shows the state close to full bottom. In both cases, the volume of the sub-tank compartment 9 expands and changes in accordance with the compression of the spring 5 as in the case of empty vehicle, and the sudden increase of the spring constant can be suppressed. Note that, as shown in FIG. 8, when the stroke is close to full bottom, the spring 5 is pressed to the fully compressed state, so the volume of the sub tank compartment 9 does not increase. Therefore, as in the case of the conventional technique, the spring constant becomes comparatively high thereafter, and the occurrence of full bottom is prevented.

FIG. 9 is a diagram comparing changes in the spring constant (k) between the present embodiment and the prior art having the sub tank 20. The curve A is a curve showing the change of the spring constant (k) of this embodiment when the vehicle is empty, and the curve B is that of the prior art. Further, the curve A'shows the change of the spring constant (k) of this embodiment at the time of loading, and the curve B'is that of the prior art. In the figure, the horizontal axis represents the stroke (S) of the axle 15, and the vertical axis represents the spring constant (k) of the air suspension. In addition, in order to compare the present embodiment with the prior art, this figure shows the case where the volume of the sub tank compartment 9 at the position where the stroke (S) is close to zero is made equal to the volume of the sub tank 20 of the prior art. Is shown. In the figure, x indicates a normal running state, Δ indicates a bumping state, and ○ indicates a state close to full bottom.

As is apparent from the figure, the spring constants (k) of the curves A and B are almost the same at the start point of the stroke (S), but are close to normal running (x), (Δ) and full-bottom. It is shown that the spring constant (k) of the present embodiment is lower in each of the strokes (◯), and good riding comfort can be obtained. Further, the reason why the spring constant (k) rises abruptly from the position close to the full bottom in the curve A is that the degree of volume expansion of the sub tank compartment 9 becomes low as described above. As shown by the curves A ′ and B ′, even in the case of loading, the case of this embodiment is lower than the spring constant (k) of the prior art in all stages, rises abruptly from a position close to the full bottom, and finally rises. This is almost the same as the spring constant of the prior art. As a result, good riding comfort can be obtained even during loading, and the occurrence of full bottom can be prevented by increasing the spring constant.

FIG. 10 is a diagram showing the relationship between the load (P) and the deflection (δ) in this embodiment. As described above, in this embodiment, the diaphragm 4 and the spring 5 can be easily replaced by removing the lid 3b. As shown in the figure, when the spring constant [K] of the spring 5 is small, the diaphragm 4 is easily deformed, so that the deflection (δ) with respect to the load (P) is large and the spring constant (k) of the air suspension is small. . On the contrary, if the spring constant [K] of the spring 5 is increased, the spring constant (k) of the air suspension becomes large. As described above, by replacing the spring 5, an air suspension having a desired spring constant (k) can be formed.

Further, since the mounting position and shape of the diaphragm 4 can be exchanged, the volume of the sub tank partition chamber 9 can be changed appropriately. Therefore, even if the volume of the sub-tank main body 3 is constant, the volume of the sub-tank compartment 9 is changed by changing the diaphragm 4, and the spring constant (k) of the air suspension is appropriately changed to obtain the air having a spring constant (k) of a desired ride comfort. A suspension can be formed.

On the other hand, in the case of a vehicle provided with an air suspension, the air in the air spring 1 and the sub-tank 2 may be discharged when the vehicle is idle to stop the vehicle. When traveling again, it is necessary to charge the air in the air spring and the sub-tank, but as described above, in the conventional technique, the air has to be introduced into the entire sub-tank 20 having a large volume, which takes time to charge. . However, in the case of the present embodiment, since it suffices to introduce air into the air chamber 1a of the air spring 1 and the sub-tank compartment 9, the charging time is shortened and the vehicle can be re-run quickly.

In the present embodiment, the external shape of the sub-tank 2 and the shapes of the diaphragm 4 and the spring 5 are shown in FIGS. 1 and 2, but they are not limited to those of the embodiment. The spring 5 may have a double structure, and the number of sub-tanks 2 is not limited to one. Further, the type of the air spring 1 connected to the sub tank 2 is not limited to that shown in the drawings.

[0022]

[Effect of device]

 According to the present invention, the following remarkable effects are obtained. (1) By adopting a structure in which the sub-tank is partitioned by a diaphragm and a spring that presses the diaphragm toward the air spring is housed in one of the sub-tank compartments, the volume of the sub-tank during a stroke can be changed according to the stroke. It is possible to reduce the spring constant of the air suspension and secure a good riding comfort. (2) When the spring is fully compressed, there is no change in the volume of the sub tank, so the spring constant at that position and beyond can be made relatively large, and the occurrence of full bottom can be prevented. (3) Since the sub-tank is partitioned by the diaphragm, charging after air discharge to reduce the vehicle height is performed quickly, and the time to return to the running state is shortened. (4) By adopting a structure in which the diaphragm and the spring are detachably housed in the sub tank, it is possible to easily form an air suspension having a desired spring constant. (5) The structure is simple, and it can be implemented at low cost without requiring a special control mechanism.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an embodiment of the present invention.

FIG. 2 is an enlarged axial sectional view showing the detailed structure of the sub tank of this embodiment.

FIG. 3 is an explanatory axial cross-sectional view showing an internal state of a sub tank during normal traveling of an empty vehicle according to the present embodiment.

FIG. 4 is an explanatory axial cross-sectional view showing an internal state of a sub tank at the time of empty car bumping according to the present embodiment.

FIG. 5 is an explanatory axial sectional view showing an internal state of a sub tank in the vicinity of an empty vehicle full bottom according to the present embodiment.

FIG. 6 is an explanatory axial cross-sectional view showing the internal state of the sub-tank during normal traveling with loading according to the present embodiment.

FIG. 7 is an explanatory axial cross-sectional view showing the internal state of the sub tank at the time of stacking bumps according to the present embodiment.

FIG. 8 is an explanatory axial cross-sectional view showing the internal state of the sub-tank in the vicinity of the loading full bottom of the present embodiment.

FIG. 9 is a diagram showing a relationship between a stroke (S) and a spring constant (k) according to the present embodiment and the prior art.

FIG. 10 is a diagram showing the relationship between the magnitude of the spring constant [K] of the spring housed in the sub tank of this embodiment, the load (P) of the air suspension, and the deflection (δ).

FIG. 11 is an explanatory axial cross-sectional view showing the internal state of the sub-tank during normal traveling of the conventional empty vehicle.

FIG. 12 is an explanatory axial cross-sectional view showing an internal state of a sub-tank in the vicinity of a conventional empty vehicle full bottom.

FIG. 13 is a diagram showing the relationship between the size of the sub tank, the load (P) of the air suspension, and the deflection (δ) in the related art.

[Explanation of symbols]

 1 Air Spring 1a Air Chamber 1b Pressing Part 2 Sub Tank 3 Sub Tank Body 3a Case Body 3b Lid 4 Diaphragm 5 Spring 6 Bolt 7 Air Pipe 8 Air Pipe 9 Sub Tank Partition Room 10 Sub Tank Partition Room 11 Bolt 12 Switching Valve 13 Main Tank 14 Leveling Valve (L / V) 15 Axle 16 Leaf spring 17 Frame 20 Sub tank

Claims (2)

[Scope of utility model registration request] 1. A sub-tank structure in which an axle is in communication with an air chamber of an air spring that is suspended on the vehicle body side. Sub-tank structure of air suspension characterized by being provided. 2. The sub-tank structure for an air suspension according to claim 1, wherein the diaphragm and the urging means are detachably housed in the sub-tank body.