JPS6230925B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of a device for freely adjusting vehicle height in order to improve high-speed stability of a vehicle.

Generally speaking, there are limits to lowering the vehicle height to prevent interference with the road surface when driving on rough roads or in urban areas, but when driving at high speeds on good roads and when interference with the road surface is not a problem, lower the vehicle height. Lowering the height lowers the center of gravity, improving driving stability and improving aerodynamic performance, which is advantageous in terms of fuel efficiency.

Therefore, a device has been proposed that can arbitrarily adjust the vehicle height as necessary, and this device will be explained with reference to FIG. 1.

A coil spring (main spring) 3 made of a spring material is disposed as a suspension spring on the outer periphery of a main body 2 of a shock absorber 1 interposed between a vehicle body and an axle.

The coil spring 3 is interposed between a lower spring receiver 4 of the main body 2 and an upper spring receiver 6 of the piston rod 5.

At the same time, an air spring 7 as an auxiliary spring is arranged inside the coil spring 3.

The air spring 7 has a closed air chamber 10 formed above the main body 2 by a bottomed cylindrical cover 8 attached to the upper spring receiver 6 and a rubber sleeve 9 connected to the opening side of the cover 8. Pressurized air from an air reservoir (not shown) or the like is supplied to the air chamber 10 via an air pipe 11 via a switching valve.

Therefore, when the pressure in the air chamber 10 of the air spring 7 is lowered, the piston rod 5 contracts relatively due to the balance with the vehicle body load, and the vehicle height decreases.On the other hand, when the pressure is increased, the vehicle height increases. be. By the way, since the spring characteristics of the coil spring 3 are linear, as shown in FIG. 2, the spring constant does not change when the vehicle height is changed, whereas the spring characteristics of the air spring 7 are generally Although it is non-linear, in this case, the strongly non-linear part is such that the rate of change in spring repulsion force with respect to stroke displacement (spring deflection) is too large and is inappropriate for the stable suspension function of the vehicle.
The rubber sleeve 9 is not used for reasons such as undesirable pressure resistance, and is assembled in such a way that the part where the spring repulsion force changes slowly and has relatively strong linearity is used as the normal range, that is, the amount of spring deflection. The change in the spring repulsion force also exhibits approximately linear characteristics.

In the figure, A shows the composite spring characteristics of the main spring and auxiliary spring when the vehicle height is raised, B shows the composite spring characteristics when the vehicle height is lowered, and C shows the spring characteristics of only the main spring. .

Generally, when lowering the vehicle height, as mentioned above, it is when driving at high speeds on good roads. In such cases, a stiff suspension is preferable to suppress rolling and pitching. In other words, a high spring constant improves maneuverability and stability. gets better.

However, with conventional devices, even if the vehicle height can be lowered, the spring constant does not increase; on the contrary, when the air pressure is low, the spring constant decreases, so there remains an issue that needs to be improved in high-speed maneuverability. .

In order to solve this problem, the present invention makes the spring characteristics of the main spring non-linear, so that when the vehicle height is high, the spring constant is made softer by decreasing the spring constant, and when the vehicle height is low, the spring constant is increased. The present invention proposes a vehicle height adjustment device that has stiff characteristics and can reliably improve maneuverability during high-speed driving and cornering.

Embodiments of the present invention will be described below based on the drawings.

In the first embodiment shown in FIG. 3, a conical spring 3A having a spring characteristic Ci (see FIG. 4) in which the spring constant increases as the amount of deflection increases is used as the main spring serving as the suspension spring. 6 and the lower spring receiver 4.

The rest of the configuration is the same as in FIG. 1, but in this way, as shown in FIG.
When the internal pressure of the conical spring 3A is lowered to lower the vehicle height, the amount of deflection of the conical spring 3A increases relatively, and the spring constant of the pressure side portion can be increased as shown in composite spring characteristic _B1 .

In Figure 4, A ₁ shows the composite spring characteristics of the main spring and auxiliary spring when the vehicle height is raised, B ₁ shows the composite spring characteristics when the vehicle height is lowered, and C ₁ shows the spring characteristics of only the main spring. .

Therefore, if the air spring 7 is weakened as an auxiliary spring and the amount of deflection of the conical spring 3A as a main spring is increased, the spring constants (expressed as slopes k ₁ and k ₂ ) at the same sprung mass load will become Since a composite spring characteristic with a large area is obtained, a stiff suspension is obtained and stability is improved.

Furthermore, if the internal pressure of the air spring 7 is increased and the amount of deflection of the conical spring 3A is reduced, the spring constant of the main spring becomes a composite spring characteristic in a region where the spring constant is small, so the spring constant as a whole becomes smaller, resulting in a softer ride. is obtained.

By the way, in order to make the spring characteristics of the main spring non-linear, as shown in Fig. 5, a two-stage (unequal) pitch spring 3B in which the winding spacing (pitch S ₁ - S ₂ ) and wire diameter change midway is used. may be provided. In this case, the outer diameter of the main spring can be kept small, which is advantageous in terms of space.

In addition, the one shown in FIG. 6 has a coil spring 3C having a multi-stage spring configuration, that is, linear spring characteristics, interposed between the upper and lower spring supports 4 and 6 as the nonlinear main spring, and an air chamber 10. An auxiliary spring (bump rubber) 3D made of urethane rubber or the like is provided inside so as to come into pressure contact between the upper end of the main body 2 of the shock absorber 1 and the upper spring receiver 6 when the vehicle height is low. When the vehicle height is low, the spring constant of the auxiliary spring 3D is added to increase the overall spring constant. Note that the number of spring stages can be further increased to three or four stages.

As described above, according to the present invention, as the main spring,
It is constructed with non-linear springs (including multi-stage springs or a combination thereof) so that the spring constant increases as the amount of deflection increases, so the spring constant can be increased at the same time as lowering the vehicle height when driving at high speeds, improving maneuverability. This significantly improves performance and stability, while also ensuring a soft ride when the vehicle height is raised, such as when driving on rough roads.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part of a conventional device, and FIG. 2 is a characteristic diagram thereof. FIG. 3 is a sectional view of a main part of the first embodiment of the present invention, and FIG. 4 is a characteristic diagram thereof. FIGS. 5 and 6 are sectional views of main parts of second and third embodiments of the present invention, respectively. 1...Shock absorber, 2...Main body, 3
A... Conical spring, 3B... Unequal pitch spring, 3C... Coil spring, 3D...
...Auxiliary spring, 4, 6... Spring holder, 7... Air spring.

Claims (1)

[Claims] 1 As suspension springs interposed between the vehicle body and the axle, a main spring made of spring material and an auxiliary spring made of air springs are installed side by side, and the internal pressure of the air springs is adjusted to achieve a high vehicle height position and a low vehicle height. The vehicle height adjustment device is equipped with a means for controlling the vehicle position and height, and the main spring is composed of a nonlinear spring whose spring constant increases as the amount of deflection increases, and the main spring is a combination of the main spring and the auxiliary spring. A vehicle height adjustment device characterized in that a spring constant value is larger at a low vehicle height position than at a high vehicle height position.