JP2005280522A - Suspension device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a suspension device capable of changing the spring constant while keeping the vehicle height constant. <P>SOLUTION: In the suspension device 20, a wheel 21 is connected with the vehicle body 22. The suspension device 20 comprises a shock absorber 23, a coil spring 24, an air spring 25, and an air spring 26. The air spring 25 is arranged in series with the coil spring 24. The air spring 26 is arranged in parallel with the coil spring 24. The air spring 25 is constituted as an air bag type air spring device. The air spring 26 is constituted as a piston cylinder type air spring device. Respective spring constants of the air spring 25 and air spring 26 are changed according to the supplied air quantity. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a suspension device for suspending automobile wheels.

  The wheels of the automobile are connected to the vehicle body by a suspension device. Generally, a suspension device includes a spring and a shock absorber, and the driving performance and riding comfort of the vehicle are determined by appropriately setting the spring constant of the spring and the damping coefficient of the shock absorber. The spring constant and the damping coefficient are determined by the designer according to the specifications of the automobile, and are evaluated as a seasoning of the design.

  Since the driving performance and riding comfort of an automobile are determined by the spring constant and the damping coefficient, if the suspension system is designed so that the spring constant and damping coefficient can be adjusted, the driver of the automobile will prefer It is possible to set the running performance and ride comfort according to the vehicle. For this reason, some conventional suspension devices employ air springs (see, for example, Patent Documents 1 to 3). However, the air spring is mainly for the purpose of adjusting the ride comfort, and there is a problem that the vehicle height changes remarkably with the adjustment of the ride comfort and greatly affects the running performance. In order to solve this problem, conventionally, a suspension device in which a coil spring and an air spring are arranged in series has been provided (see, for example, Patent Document 4).

JP 2001-121936 A JP2003-146042A JP 2001-1730 A JP 2003-89309 A

  FIG. 4 is a schematic view of a suspension device in which a conventional coil spring and air spring are arranged in series.

  As shown in the figure, the suspension device 1 includes a coil spring 2, an air spring 3, and a shock absorber. In the same figure, the shock absorber is not shown, but is arranged in parallel with the coil spring 2 and the air spring 3. The lower end of the coil spring 2 is connected to a suspension arm 5 to which a wheel 4 is attached, and the upper end of the air spring 3 is connected to the vehicle body 7 side via a support shaft 6. The coil spring 2 and the air spring 3 are arranged in series, and the air spring 3 is held by spring holders 8 and 9.

  As shown in FIGS. 4A to 4C, the position of the spring holder 9 is adjusted. The position of the spring holder 9 is adjusted by operating the adjustment member 10. FIG. 2A shows a state where the spring holder 9 is set to the lowest position, and the air spring 3 is hardly filled with air. FIG. 2C shows a state in which the spring holder 9 is set at the uppermost position, and the air spring 3 is filled with the maximum amount of air. FIG. 5B shows a state where the spring holder 9 is set at the intermediate position, and the air spring 3 is filled with an intermediate amount of air. The spring constant of the air spring 4 varies depending on the amount of air that is filled.

  In this way, by adjusting the position of the spring holder 9, the spring constant of the air spring 3 is changed while the overall height of the suspension device 1 is kept constant. That is, the spring constant of the suspension device 1 (the combined spring constant of the coil spring 2 and the spring constant of the air spring 3) is adjusted while the vehicle height is kept constant.

  However, the operation of adjusting the position of the spring holder 9 is performed by operating the adjustment member 10 with a dedicated tool after the vehicle is jacked up and the wheel is removed. For this reason, the operation | work which changes the spring constant of the suspension apparatus 1 was not easy, and the driver | operator could not change suitably as needed.

  Therefore, an object of the present invention is to provide a suspension device that can change the spring constant with a simple operation while keeping the vehicle height constant.

  (1) In order to achieve the above object, a suspension device according to the present invention includes a shock absorber, a coil spring, a first spring device that is arranged in series with the coil spring, and whose spring constant can be changed by air pressure. And a second spring device that is arranged in parallel to the coil spring and whose spring constant can be changed by pneumatic pressure.

If the spring constant of the coil spring is set to k1 and the spring constant of the first spring device is set to k2, the combined spring constant KS of the coil spring and the first spring device is expressed by (Equation 1). The
KS = k1 * k2 / (k1 + k2) -------------- (Formula 1)
From (Equation 1), the combined spring constant KS is smaller than the spring constant k1 of the coil spring and the spring constant k2 of the first spring device.
On the other hand, if the spring constant of the second spring device is set to k3, the combined spring constant KP of the coil spring and the second spring device is expressed by (Equation 2).
KP = k1 + k3 --------------------- (Formula 2)
From (Expression 2), the composite spring low order KP is larger than the spring constant k1 of the coil spring and the spring constant k3 of the second spring device.

  Therefore, when the second spring device is operated, the combined spring constant K of the entire suspension device tends to increase, and when the first spring device is operated, the combined spring constant of the entire suspension device is increased. K tends to be small.

  Since the first spring device and the second spring device are actuated by pneumatic pressure, remote operation is easily realized. That is, in a vehicle equipped with the suspension device, the driver can easily operate the first spring device and the second spring device, and the spring constant K is easily adjusted. Moreover, since the first spring device and the second spring device are driven by pneumatic pressure, the vehicle height can be freely adjusted.

  (2) The first spring device or the second spring device is an air spring device whose spring constant is changed by supplying / discharging air to / from the rubber casing, or a spring by supplying / discharging air. A piston-cylinder spring device in which the constant is changed may be employed.

  According to the present invention, the first spring device driven by air pressure is arranged in series with the coil spring, and the second spring device driven by air pressure is arranged in parallel with the coil spring. Therefore, in a vehicle equipped with the suspension device, the adjustment of the vehicle height and the spring constant of the suspension device as a whole are easily adjusted. Therefore, the spring constant of the entire suspension device is arbitrarily set while the vehicle height is kept constant, and the driver can easily realize desired traveling performance for the vehicle.

  Hereinafter, the present invention will be described in detail based on preferred embodiments with appropriate reference to the drawings.

<First Embodiment>
FIG. 1 is a front view of a suspension device according to a first embodiment of the present invention.
The suspension device 20 is a device for connecting a vehicle wheel 21 to a vehicle body 22 and suspends a front wheel in the present embodiment. A suspension arm 27 is connected to the wheel 21. The suspension arm 27 is also connected to the vehicle body 22 and defines the geometry of the wheel 21 with respect to the vehicle body 22. Therefore, the wheel 21 moves on the locus defined by the suspension arm 27.

  In this embodiment, the suspension type is a strut type, but the present invention is not only applied to such a type of suspension, but can be applied to other various types of suspensions. In the present embodiment, the suspension device 20 suspends the front wheel, but it is needless to say that the suspension device 20 may be used to suspend the rear wheel.

  The suspension device 20 includes a shock absorber 23, a coil spring 24, an airbag type air spring 25 (first spring device), and an air cylinder type air spring 26 (second spring device). . The suspension device 20 according to the present embodiment is characterized in that an air spring 25 is arranged in series with the coil spring 24 and an air spring 26 is arranged in parallel with the coil spring 24. .

  The shock absorber 23 is a damper that suppresses vibrations of the wheels 21. The shock absorber 23 has a known configuration, and a damper rod 29 slides along the axial direction with respect to the damper tube 28. At this time, the force for sliding the damper rod 29 is proportional to the sliding speed of the damper rod 29 (that is, the moving speed of the wheel 21). A rear end portion of the damper tube 28 is connected to the wheel 21. Both are connected via a pin 37. On the other hand, the end of the damper rod 29 is connected to the vehicle body 22. The damper rod 29 is fixed to the vehicle body 22 via the mount unit 30. The mount unit 30 has a known configuration and is fastened to the vehicle body 22 by bolts 31. Therefore, when the wheel 21 vibrates, the damper tube 28 slides relative to the damper rod 29.

  The air spring 26 is fixed to the shock absorber 23. The air spring 26 has a known configuration and includes a tube 32 and a rod 33. The tube 32 is fixed to the damper tube 28. The rod 33 is inserted into the tube 32, and air is sealed in an air chamber defined by both. That is, the tube 32 and the rod 33 constitute an air spring, and the spring constant k3 of the air spring 26 is determined by the amount of air enclosed in the air chamber. The upper end of the rod 33 is in contact with a spring holding member 36 described later, and the spring holding member is pressed with a pressing force corresponding to the air pressure in the air chamber. However, when air is discharged from the air chamber, the force with which the air spring 26 presses the spring holding member 36 becomes zero. The tube 32 includes a supply port 34 through which air is supplied, and a discharge port (not shown) through which air is discharged. An air supply pipe is connected to the supply port 34, and an appropriate amount of air is appropriately supplied. The air in the tube 32 is discharged from the discharge port when necessary.

  The coil spring 24 is attached to the shock absorber 23. Specifically, the coil spring 24 is attached to the tube 32 of the air spring 26 via a spring seat 35. The lower end portion of the coil spring 24 is placed on a spring seat 35, and the upper end portion of the coil spring 24 is held by a spring holding member 36. The spring holding member 36 is formed in a circular shape, and the damper rod 29 passes through the center thereof. The spring holding member 36 is slidable relative to the damper rod 29. The coil spring 24 is configured by winding a spring steel having a predetermined wire diameter in a spiral manner a predetermined number of times, and its spring constant k1 is determined.

  The air spring 25 has a known configuration and is disposed above the coil spring 24. The air spring 25 includes an airbag 38 (rubber casing). The airbag 38 is disposed between the spring holding member 36 and the mount unit 30. The spring constant k2 of the air spring 25 is determined by the amount of air sealed in the airbag 38. Although not shown, the airbag 38 is provided with a supply port for supplying air and a discharge port for discharging air, like the air spring 26. An air supply pipe is connected to the supply port, and an appropriate amount of air is appropriately supplied. The air in the airbag 38 is discharged from the discharge port when necessary.

  As described above, when the wheel 21 vibrates, the damper tube 28 of the shock absorber 23 vibrates with respect to the damper rod 29. Since the air spring 26 is fixed to the shock absorber 23, the vibration of the shock absorber 23 causes the vibration of the air spring 26 as long as the air spring 26 is in contact with the spring holding member 36. The vibration of the shock absorber 23 also causes the coil spring 24 to vibrate. As shown in the figure, in the suspension device 20, an air spring 25 is arranged in series with the coil spring 24, and an air spring 26 is arranged in parallel with the coil spring 24.

  In the suspension device 20, the combined spring constant KS of the coil spring 24 and the air spring 25 is expressed by the above (formula 1). The combined spring constant KP of the coil spring 24 and the air spring 26 is expressed by the above (Equation 2). Therefore, the combined spring constant K of the suspension device 20 as a whole tends to increase as the air spring 26 operates, and the combined spring constant K of the suspension device 20 decreases as the air spring 25 operates. There is a tendency.

  For example, when the air in the airbag 38 of the air spring 25 is discharged and the air spring 26 is supplied with air, the combined spring constant of the suspension device 20 as a whole is maintained while keeping the vehicle height constant. K increases. When air is supplied to the airbag 38 of the air spring 25 and air is discharged from the tube 32 of the air spring 26, the overall height of the suspension device 20 is maintained while the vehicle height is kept constant. The spring constant K becomes smaller.

  Moreover, since the air spring 25 and the air spring 26 are pneumatically controlled, the history operation is simple. Therefore, in the automobile equipped with the suspension device 20, the driver can freely adjust the spring constant K by operating the air spring 25 and the air spring 26 from within the vehicle. Therefore, the driver can achieve his or her desired driving performance while keeping the vehicle height constant.

  In the present embodiment, the air spring 25 is configured as an air spring device including an airbag 38 and the air spring 26 is configured as a piston-cylinder spring device. However, the air spring 26 includes an air spring. The air spring 25 may be configured as a piston-cylinder spring device. In the present embodiment, the air spring 25 and the air spring 26 are configured as pneumatic devices, but may be configured as a hydraulic device including a hydraulic cylinder and a piston instead. is there.

<Second Embodiment>
FIG. 2 is a front view of the suspension device according to the second embodiment of the present invention.

  Similar to the suspension device 20 according to the first embodiment, the suspension device 40 according to the present embodiment includes a shock absorber 23, a coil spring 24, and an airbag-type air spring 25 (first spring device). And an air cylinder type air spring 26 (second spring device), the air spring 25 is arranged in series with the coil spring 24, and the air spring 26 is arranged in parallel with the coil spring 24. Has been. The suspension device 40 is different from the suspension device 20 in that the coil spring 24 and the air spring 25 are arranged in parallel with the shock absorber 23. In addition, about another structure, it is the same as that of the suspension apparatus 20 which concerns on the said 1st Embodiment.

  As shown in the figure, the coil spring 24 and the air spring 25 are arranged in series, and these are arranged between the vehicle body 22 and the suspension arm 27. The air spring 25 is fixed to the vehicle body 22 via the mount unit 41. The coil spring 24 is disposed between the spring holding member 42 of the mount unit 41 and the suspension arm 27. In the figure, a supply port 43 for supplying air to the airbag 38 of the air spring 25 is shown.

  Also in this suspension device 40, the combined spring constant KS of the coil spring 24 and the air spring 25 is expressed by the above (formula 1), and the combined spring constant KP of the coil spring 24 and the air spring 26 is expressed by the above (formula 2). expressed. Therefore, the combined spring constant K of the suspension device 40 as a whole tends to increase as the air spring 26 operates, and the combined spring constant K of the suspension device 40 decreases as the air spring 25 operates. There is a tendency. As a result, when the air in the airbag 38 of the air spring 25 is discharged and the air spring 26 is supplied with air, the height of the automobile is kept constant, and the combined spring of the suspension device 40 as a whole The constant K increases. When air is supplied to the air bag 38 of the air spring 25 and air is discharged from the tube 32 of the air spring 26, the overall height of the automobile 40 is kept constant, and the overall suspension device 40 is synthesized. The spring constant K becomes smaller. Therefore, in the automobile equipped with this suspension device 40, the driver can freely adjust the spring constant K by operating the air spring 25 and the air spring 26 from within the vehicle. As a result, the driver can While keeping the height constant, it is possible to achieve the desired running performance.

<Third Embodiment>
FIG. 3 is a front view of a suspension device according to a third embodiment of the present invention.

  Similar to the suspension device 20 according to the first embodiment, the suspension device 50 according to the present embodiment has a shock absorber 23, a coil spring 24, an air spring 25 (first spring device), and an air spring 51. (Second spring device), an air spring 25 is arranged in series with respect to the coil spring 24, and an air spring 51 is arranged in parallel with the coil spring 24. The suspension device 50 differs from the suspension device 20 in that the coil spring 24, the air spring 25, and the air spring 51 are arranged in parallel with the shock absorber 23, and the air spring 51 is configured as a bellows type air spring device. It is a point that has been. In addition, about another structure, it is the same as that of the suspension apparatus 20 which concerns on the said 1st Embodiment.

  As shown in the figure, the coil spring 24 and the air spring 25 are arranged in series, and are arranged between the vehicle body 22 and the suspension arm 27. The air spring 25 is fixed to the vehicle body 22 via the mount unit 41. The coil spring 24 is disposed between the spring holding member 42 of the mount unit 41 and the suspension arm 27. In the figure, a supply port 43 for supplying air to the airbag 38 of the air spring 25 is shown.

  The air spring 51 includes a bellows 52, which extends upward when air is supplied from an air supply port (not shown) and downward when air is discharged from an air discharge port (not shown). Shrink. The spring constant k3 of the air spring 51 is determined by the amount of air supplied into the bellows 52. Since the air spring 51 is disposed between the suspension arm 27 and the spring holding member 42, the air spring 51 is disposed in parallel with the coil spring 24.

  Also in this suspension device 50, the combined spring constant KS of the coil spring 24 and the air spring 25 is expressed by the above (formula 1), and the combined spring constant KP of the coil spring 24 and the air spring 51 is expressed by the above (formula 2). expressed. Therefore, the combined spring constant K of the suspension device 50 as a whole tends to increase when the air spring 51 operates, and the combined spring constant K of the suspension device 50 decreases as the air spring 25 operates. There is a tendency. Thus, when the air in the airbag 38 of the air spring 25 is discharged and the air spring 51 is supplied with air, the height of the automobile is kept constant, and the combined spring of the suspension device 50 as a whole is maintained. The constant K increases. When air is supplied to the air bag 38 of the air spring 25 and air is discharged from the bellows 52 of the air spring 51, the overall height of the suspension device 50 is maintained while the vehicle height is kept constant. The spring constant K becomes smaller. Therefore, in the automobile equipped with the suspension device 50, the driver can operate the air spring 25 and the air spring 51 from the inside of the vehicle to freely adjust the spring constant K. As a result, the driver can While keeping the height constant, it is possible to achieve the desired running performance.

  The present invention can be applied to a suspension device that suspends wheels.

FIG. 1 is a front view of a suspension device according to a first embodiment of the present invention. FIG. 2 is a front view of the suspension device according to the second embodiment of the present invention. FIG. 3 is a front view of a suspension device according to a third embodiment of the present invention. FIG. 4 is a schematic view of a suspension device in which a conventional coil spring and air spring are arranged in series.

Explanation of symbols

DESCRIPTION OF SYMBOLS 20 ... Suspension device 21 ... Wheel 22 ... Vehicle body 23 ... Shock absorber 24 ... Coil spring 25 ... Air spring 26 ... Air spring 27 ... Arm 28 ... Damper Tube 29 ... Damper rod 32 ... Tube 33 ... Rod 35 ... Spring seat 36 ... Spring holding member 38 ... Air bag 40 ... Suspension device 42 ... Spring holding member 50 ... Suspension device 51 ... Air spring 52 ... Bellows

Claims (3)

Shock absorbers,
Coil springs,
A first spring device which is arranged in series with the coil spring and whose spring constant can be changed by air pressure;
A suspension device comprising: a second spring device that is arranged in parallel with the coil spring and whose spring constant can be changed by air pressure. The first spring device includes:
2. The air spring device in which a spring constant is changed by supplying / discharging air to / from the rubber casing or a piston-cylinder spring device in which the spring constant is changed by supplying / discharging air. Suspension system. The second spring device is
3. An air spring device in which a spring constant is changed by supplying / discharging air to / from a rubber casing or a piston-cylinder spring device in which a spring constant is changed by supplying / discharging air. The suspension device described in 1.

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