JPS5977914A - Suspension of automobile - Google Patents

Abstract

PURPOSE:To obtain optimal steering characteristics according to the variations of loads by a method in which a fluid path area variable-type attenuation variable dumper unit is provided, and during the high loading, the ratio of the front wheel dumper attenuation to the rear wheel dumper attenuation is increased. CONSTITUTION:Signal 4a from a load sensor 4 is put in a controller 3. When the controller 3 receives a load signal above a set load, a drive signal 3a is sent out to actuators 2a, and the attenuation CR of the fluid path area variable dumper units 2a for the rear wheels is made smaller. In this case, since the attenuation CF of the dumper units for the front wheels is invariable, CF/CR ratio becomes greater and the under steer becomes stronger. At the time of low loading, CF/CR ratio is made smaller. Therefore, optimal steering characteristics according to loads can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automobile suspension, and more particularly to an automobile suspension that includes a damper with variable damping force and that controls the damping force depending on the situation.

In automobile suspensions, the damping force of a damper is controlled according to the situation, for example, as shown in Utility Model Application No. 55-109008, the damping force is changed according to the vehicle speed to provide always favorable handling characteristics. It is known that it is possible to obtain this. This enhances understeer characteristics at high speeds, and provides neutral steer or weak oversteer characteristics at low speeds, ensuring stable handling characteristics at all times in response to changes in vehicle speed.

However, there are various factors other than vehicle speed as changes in the situation that require changes in handling characteristics. For example, changes in load are also closely related to handling characteristics, and changes in load affect handling characteristics. In other words, the understeer characteristics become weaker under high loads and stronger under low loads.

Therefore, sufficient running stability cannot be ensured only by control according to vehicle speed.

For example, when the number of passengers in a car increases or the load on the car increases, the understeer characteristics become weaker and the car becomes more prone to oversteer. The understeer characteristic is particularly effective in correcting disturbances when the car is subjected to disturbances, and when this characteristic weakens, the straight-line stability decreases, making the car dangerous especially at high speeds.

However, on the other hand, if the understeer characteristics become too strong (too much), the response during steering becomes slow, and the maneuverability becomes poor.
＜Because of this, it is not desirable to simply strengthen this. Therefore, it is desirable to always be able to obtain appropriate understeer characteristics when the load changes.

The present invention has focused on this point, and an object of the present invention is to provide an automobile suspension that can always obtain desirable handling characteristics in response to changes in load.

In order to achieve this objective, the suspension of the present invention is characterized in that the damping force of the damper is made variable, and this is controlled in accordance with changes in load so as to always obtain desirable suction characteristics. .

That is, the suspension 7 of the present invention is provided with a damper unit that changes the damping force by changing the fluid passage area in the damper on at least one of the front wheel and the rear wheel among the front and rear wheel suspensions, and the damping force of this damper unit is changed. is controlled by electromagnetic means, and this electromagnetic means receives the output of a load sensor that detects the load on the vehicle body and controls the damping force of the front wheel damper unit against the damping force of the rear wheel damper unit when the load is high. The present invention is characterized in that it is controlled by a control means that outputs a control signal that makes the ratio larger than when the load is low.

Here, making the ratio of the damping force of the front wheel side damper unit to the rear wheel side damping force larger at high loads than at low loads means that when the front wheel side damping force is constant at high loads, the ratio of the damping force of the rear wheel side damper units is There are three cases: decreasing the damping force, conversely increasing the front wheel while keeping the rear wheel constant, and changing both in the opposite direction, that is, increasing the front wheel and decreasing the rear wheel. (In each case, the damping force is changed in the opposite direction to the above when the load is low.)

Hereinafter, to simplify the explanation, the damping forces of the front and rear wheel damper units will be expressed as CF and CR, respectively. CF's CR
Since the ratio to CF is expressed as CF/CR, the above 3
In one case, it means that the CF/CR at high load is made larger than the CF/CR at low load.

This can be expressed as shown in Table 1.

"L-1 Increasing CP/CR strengthens the understeer characteristics, so it is possible to prevent the understeer characteristics from being weakened by high loads, and it is possible to maintain appropriate understeer characteristics. The present invention, as described above,
/CR is changed depending on the magnitude of the load, so it is possible to always obtain the desired understeer characteristics.
Good maneuverability and running stability can be achieved.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1 shows an automobile equipped with the suspension of the present invention. In this embodiment, out of the front wheel suspensions 1, 1 and the rear wheel suspensions 2.2, damping is applied only to the rear wheel suspensions 2, 2. Equipped with a damper unit with variable force,
This is controlled by the controller 3.

The controller 3 includes a load sensor 4 that detects the magnitude of the load.
The output from the rear wheel is input through the lead wire 4a, and the rear wheel suspension 2 has a built-in damper unit with variable damping force.
, 2 through lead wires 3a.

As shown in FIG. 2, each suspension 2.2 has an actuator 2a comprising electromagnetic means.

2a, a damper unit 21) 12b whose damping force can be changed by this, and this damper unit 1-2b.
, 2b is further provided with a coil spring 2C12C, and the output of the controller 3 which receives the signal from the load sensor 4 is sent to the actuators 2a, 2a of the left and right rear wheel suspensions 2, 2 through a lead wire 3a. is input. The actuator receiving this output, that is, the control signal, controls the damping force of the variable damping force goomba units l-2b, 2b to a magnitude corresponding to the load.

For example, if the load sensor 4 detects a load greater than a predetermined value and outputs a signal indicating a high load, the controller 3 that receives this will drive the actuators 2a, 2a to drive the rear wheel f7 2b, damping force (CR) of 2b
, thereby increasing CF/'CR.

Specifically, as shown in FIG. 3, for example, the load sensor 4
When the output of the comparator 3A exceeds a predetermined value, the power of the comparator 3A of the controller is turned on, and the base voltage of the transistor 3B connected to the output of the comparator 3 is increased to turn on the transistor 3B. The damping force of the damper unit can be reduced by driving the actuators 2a, 2a (solenoids of electromagnetic means) connected to the collector side of the transistor 3B.

Next, we will discuss a specific example of a damper unit with variable damping force in the fourth section.
This will be explained in detail with reference to FIG.

As shown in FIG. 4, the suspension 2 has an upper end fixed to a part 10 of the vehicle body via an elastic body 11, and has an air chamber 12.
a lower case 16 consisting of an outer cylinder 14 and an inner cylinder 15 that are assembled so that the upper end can go in and out of the lower end of the upper case, and a bellows 17 that airtightly connects the upper and lower cases 13°16. , a piston rod 18 coaxially penetrating the inside of the upper and lower cases 13 and 16 and slidable up and down with respect to the inner cylinder 15 of the lower case 16, and a main valve fixed to the lower end of this piston rod 18]9 and a bottom valve 20 fixed to the lower end of the inner cylinder 15, and the main pulp 19 divides the oil chamber inside the inner cylinder 15 into a chamber A above the main valve 19 and a chamber B below the main valve 19. Cylinder 14
The reservoir chamber C between the inner cylinder 15 and the inner cylinder 15 is communicated with the upper end of the A chamber at the upper end, and with the lower end of the B chamber at the T'' end.A control rod 21 passes vertically through the center of the piston rod 18. The upper end 21a of this control rod 21 is engaged with a rotation key 22 rotated by an external force so as to be able to transmit rotational force.The lower end of this control rod 21 has a chamber A and a chamber B. An orifice 21b is provided which communicates with a communication hole 18b drilled in the lower end 18a of the piston rod 18 so that the orifice 21b and the lower end 18a of the piston rod communicate with each other by rotation of the control rod 2. Communication with the hole 18b is turned on and off.

The lower end of the control rod 18, the main valve 19 and the bottom valve 2
Details of the structure of 0 will be described later with reference to FIG.

The relative vertical movement of the upper case 13 and the lower case 16 is caused by the air spring provided by the air chamber 12 as well as by the upper and lower cases 13.
Upper and lower spring supports 213a fixed to 16,
Spring 30 held between 1 and 62 (2 in Fig. 2)
a) is elastically absorbed. Brackets 16b and 16c fixed to the outer surface of the lower case 16 are for fixing a wheel support structure including a wheel knob that rotatably supports the wheels. be held movably. -111 That is, the vehicle body is suspended by wheels and elastically supported so as to be movable up and down.

The suspension 2 configured as described above has a lower goo 2.
The A, B, and C chambers in the damper 16, the communication passages that communicate these, and the valves 19 and 20 constitute a damper unit, and generate a damping force. The details of the structure of the damping unit that generates the damping force will be explained below with reference to FIG.

As shown in FIG. 5, the main valve 19 is formed with a contraction side orifice 19a and an expansion side orifice 19b.
9d has been set. A contraction side orifice 20a and an expansion side orifice 20b are similarly formed in the bottom valve 20, and a valve 20C120d is provided for each.

In the part of the main valve 19 where chambers A and B are adjacent, the two chambers are normally (at low loads) in communication only through the orifices 19a and 19b, or at high loads the control rod 21 is rotated (core). o-/l/orifice 21b and h at the lower end of rod 21.

lower end of stone rod 18], communication hole IBb of 8a
The A and B chambers are communicated with each other through a communication hole 18A that is open to the B chamber from the inside of the orifice 21b at the lower end of the control rod 21. Therefore, the fluid passage area between chamber A and chamber B is large (as a result, the damping force of this damper unit becomes small).

The control rod 21 is rotated by rotating the rotation key 22 engaged with the upper end 21a (for example, 90 degrees), thereby opening the orifice 21b and the communication hole 18b.
Turns communication on and off. The rotary key 22 is driven and rotated by electromagnetic means such as a renoid, and performs variable control of the damping force of the damper unit.

When using a damper unit configured as described in 2 above on the rear wheel side, the orifice 21b of the control rod 21 is turned on when the load is low to reduce the fluid passage area between chambers A and B. Then, when the load sensor detects a high load, the orifice 21b is turned on to increase the area and reduce the damping force. Also, when using this on the front wheel side, turn on the orifice 21b when the load is low and turn it off when the load is high.Furthermore, when using this on both the front and rear wheels, use the above two types. You can use them together as is.

The automobile suspension according to the present invention has the above-mentioned features 1.
(We use a damper with variable damping force and control it according to changes in load to make the CF/CR thicker at high loads, so the understeer characteristics, which are weakened at high loads, can be made to the desired strength.) It is possible to maintain stable running regardless of changes in load.

In the above embodiment, the magnitude of the damping force is switched between two types, large and small, but this is due to the difference between the orifice 21b and the communication hole 1.
By continuously changing the communication cross-sectional area of 8b, it can be changed continuously, and if the output of the load sensor is also a continuous analog value, it can be continuously changed in response to subtle changes in load. Control is also possible. Of course, it goes without saying that multistage control in which this is divided into three or more stages is also possible.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an automobile equipped with the suspension of the present invention, FIG. 2 is a system diagram of an embodiment of the suspension of the present invention, FIG. 3 is a circuit diagram showing a specific example of FIG. 2, and FIG. The figure is a cross-sectional view showing an example of a damper unit used in the suspension of the present invention, and FIG. 5 is a cross-sectional view showing the main part of FIG. 4 in detail. J, 2・Suspension 3・・・・Controller 4・
・Load sensor 2a...Actuator 12 ・
・Air chamber 13...Upper Ken]4...
...Outer tube 15...Inner tube 16.
...Lower case 18 ... Piston rod 19 ... Main valve 20 ... Bottom valve 18b ... Communication hole 21 ... Control rod 21b ... Orifice Su 2
2... Rotation key - Fig. 1 °□ Fig. 2 - ( Fig. 4 21a 22

Claims (1)

[Claims] Suspension means for suspending the vehicle body on the front wheels and rear wheels, a damper unit that changes the damping force by changing the fluid passage area, which is provided on either the front wheel or the rear wheel (both the front wheel and the rear wheel). An electromagnetic means for changing the fluid passage area of the damper unit, a load sensor for detecting the vehicle body load, and an output from the load sensor to calculate the ratio of the damping force of the front wheel damper unit to the damping force of the rear wheel damper unit. An automobile suspension comprising a control means for inputting a control signal to the electromagnetic means which is larger when the load is high than when the load is low.