JPS5973311A - Suspension of car - Google Patents

Abstract

PURPOSE:To prevent decreasing of the ground contact force of each of front wheels, by a method wherein, in a front engine, front drive car, the spring constant of a spring means, located parallel to a damper, is varied according to the output of an acceleration sensor, and a spring constant ratio between a front and a rear wheel is varied. CONSTITUTION:An acceleration signal, detected by an acceleration sensor 5, is inputted to a controller 3. When the acceleration exceeds a given value and indicates sudden start and sudden acceleration, the controller 3 outputs a control signal to actuators 1a and 2a, a spring constant KF of a spring 1b of each of front wheels is decreased, and a spring constant KR of a spring 2b of each of rear wheels is increased. Thus, KF/KR is decreased, and this prevents decreasing of the ground contact force of each of the front wheels. In an ordinary condition, the output of the acceleration sensor 5 is decreased, and a spring constant ratio is increased. This constitution permits prevention of reduction in the ground contact force, produced when a car starts suddenly, of each of the front wheels.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automobile suspension, and particularly to a suspension for a front engine, front drive automobile, in which the spring constant of an air spring or the like is controlled in accordance with the acceleration of the vehicle.

In a front-engine, front-dry vehicle, the front wheels are the driving wheels, so when you want to suddenly increase the engine speed and transmit the driving force to the road, such as when starting suddenly or accelerating suddenly, In particular, it is desirable that the ground contact force of the front wheels be large. However, when a large acceleration is applied to the vehicle body, such as in the case of a sudden start or sudden acceleration, the moment of inertia of the vehicle body acts in a direction that tilts the vehicle body backward relative to the center of gravity. In other words, the road surface moves forward with respect to the car body, and a force is applied around the center of gravity of the car body in the direction of tilting the car body backwards.This is because when a sudden forward driving force is applied to the tires, the tire forward on the ground.

This is because a reaction force toward .

Therefore, this force acts to lift the front part of the vehicle body and lower the rear part, reducing the ground contact force of the front wheels.

For this reason, front-engine, front-drive vehicles have a problem in that the full rotational force of the tires cannot be sufficiently transmitted to the road surface when the vehicle suddenly starts or accelerates. At this time, the decrease in the ground contact force of the front wheels is greater as the spring constant of the front wheel suspension is larger (harder). In other words, if the spring constant of the front wheels is thick, when a force that lifts the front of the vehicle body is applied due to acceleration, there is a strong tendency for the front wheels to be lifted along with the vehicle body, and the ground contact force of the tires tends to decrease significantly.

Further, the spring constant of the rear wheel also has a large effect on the relationship between the spring constant of the front wheel and the ground contact force of the front wheel. That is, if the spring constant of the front wheel suspension is kept constant and only the spring constant of the rear wheel is changed, the larger the spring constant of the rear wheel, the smaller the decrease in ground contact force during acceleration of the front wheel. In other words, the smaller the spring constant of the rear wheel suspension, the greater the inclination of the vehicle body during acceleration, the lower the ground contact force of the front wheels, and the lower the efficiency of transmitting driving force to the road surface.

In front-engine, front-drive cars, the force is the acceleration (forward) that occurs when starting suddenly or accelerating suddenly.
When this is large, it is desirable to reduce the spring constant of the front wheel suspension and increase the spring constant of the rear wheel in order to efficiently start and accelerate the vehicle.

Conventionally, it is known that the damping force of the damper is changed according to the vehicle speed, and is controlled according to the strength and weakness of the understeer custom-made.
No. 8), there is no known system in which the damping force of a damper or the spring constant of a suspension is changed in response to the magnitude of acceleration in order to solve the above-mentioned problem in front-engine, front-drive vehicles.

Focusing on this point, the present invention has developed a suspension system that prevents the ground contact force of the front wheels, which are driven by front wheels that are tilted due to inertia and is driven by inertia, from decreasing when a front engine, front drive vehicle suddenly starts or accelerates. The purpose is to provide

In the suspension of the present invention, at least one of the front and rear wheel suspensions is provided with a spring means such as an air spring that changes a spring constant in parallel with a damper, and the spring constant of this spring means is controlled according to the output of an acceleration sensor (- 1) The ratio of the spring constant of the front wheel suspension to the spring constant of the rear wheel suspension is made smaller during sudden starts and sudden accelerations (hereinafter simply referred to as sudden accelerations) than under normal conditions. The acceleration sensor here is one that detects when the acceleration of the vehicle exceeds a predetermined value, such as when a sudden start or sudden acceleration occurs, and it may be one that differentiates the output of a speedometer. For example, various types of well-known accelerometers that detect the rate of change in the amount of depression of the accelerator pedal may be used.

Here, making the ratio of the spring constant of the front wheel suspension to the spring constant of the rear wheel suspension smaller than normal during sudden acceleration means that the spring constant of the rear wheel side is increased when the spring constant of the front wheel side is assumed to be completely constant during sudden acceleration. conversely, keeping the rear wheel constant and decreasing the front wheel, and changing both in the opposite direction, i.e. decreasing the front wheel,
This includes three cases where the rear wheel side is made larger (in each case, the spring constant changes in the opposite direction to the above when not accelerating).Hereinafter, for the sake of simplifying the explanation, we will use the front and rear wheels. The spring constants of the spring means of the suspension are respectively expressed as Kl" and KR. Since the ratio of KF to R is expressed as KF/KR, the above three cases mean that KF during acceleration
/ i (R, i means that it is smaller than K F / K R when not accelerating.

By reducing K1”/KRi, it is possible to suppress the lifting of the front wheels during sudden acceleration, and it is possible to reliably transmit the driving force of the front engine/front drive vehicle to the road surface.

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

FIG. 1 shows an automobile equipped with a suspension/control system according to an embodiment of the present invention, and FIG. 2 shows a system diagram of its main parts. In this embodiment, front wheel suspension 1.1,
Accumulators IA and 2A' for varying spring constants are provided in the rear wheel suspensions 2 and 2, respectively, and are controlled by a controller 3.

The controller 3 receives the output from the acceleration sensor 5 provided in the speed make 4 and detects the magnitude of acceleration through the lead wire 3a, and inputs the output from the front and rear wheel suspension 1. which is used to change the spring constant. II2.2 accumulator LA
, lead wire 3b to 2A.

Control signals are sent through 3ci.

As shown in Figure 2, each suspension 7゜]i2.2
Actuator 1 consists of electromagnetic means. a + 1
．． Accumulators IA, 2A with a i 2 a + 2 a f are connected, and each air chamber in the accumulators IA, 2A is pumped by this electromagnetic means.
By communicating the air chamber 1i2,2 with the air chamber in the spring, the spring constant KF of the air spring is changed. A controller that receives a signal from the acceleration sensor 5'
The output from 513 is lead wire 3b.

Suspension of left and right front and rear wheels through 3ci 7yon 1, x; 2
, 2 accumulator IA, 2A actuator 1
Input to a + 1 a; 2 a + 2 a. The actuators 1a+1a:2, a+2a that receive this output, that is, the signal from the acceleration sensor 5, control the spring constants of the air springs ib, 1bi21)+2b to become smaller or larger.

For example, if the acceleration height 5 detects an acceleration of a predetermined value or more and outputs a full signal (voltage of a predetermined value or more) indicating high acceleration (sudden start, sudden acceleration, etc.), it will receive this signal. The controller 3 is actuator I a r ], a
: Drive the air spring jb of the front wheel by driving 2a and 2a, ]
, b spring constant (K F ) k is small, rear wheel air spring 2b.

2b's bounce constant (i < R) 1 large, so K, 1? /I<I<1 (, make smaller.

Specifically, for example, as shown in FIG. 3 (C), when the output of the acceleration sensor 5 exceeds a predetermined value, the positive input of the cono-parator 3A of the controller 3 increases, outputting a high output (11), and increasing the output of the comparator 3A. Some 3B in the output of
The base voltage of the transistor 3C connected through 2 is lowered to turn off this transistor 3C4-, and the base voltage of the transistor 3D connected to the output to the conoparator 3 is increased to turn on all of the transistors 3D. The front wheel side actuator 1a l la (nonoid of electromagnetic means) connected to the collector side of the transistor 3C is demagnetized and the front wheel side suspension 71 is
．． While decreasing the spring constant (K F ) of J by 2,
The rear wheel actuator 12a, 2a (non-noid magnetic means) connected to the collector side of the latter transistor 3D drives the rear wheel suspension 2.2+7.
)(/fne constant (KR)i becomes larger, thereby K F
/ K J ((il- can be made smaller to suppress the decrease in the ground contact force of the front wheels during sudden acceleration. In normal conditions, the output of the acceleration sensor 5 is less than the predetermined value, so the output of the comparator 3A is The output becomes low (L), and the transistor 3C connected via the inverter 3B is turned on, increasing the spring constant (KF) on the front wheel side and increasing the spring constant (Ki (,
) is decreased and KF/KR is increased.

Next, a specific example of a variable spring constant air spring suspension in which the spring constant is reduced by J pivoting of the actuator as described above will be explained in detail with reference to FIG. (It is designated as suspension 7 for the rear wheels.) As shown in FIG.
an outer cylinder 14 and an inner cylinder 15 that are assembled into the lower end of the upper case so that the upper end can fully enter and exit.
・The lower case 16, the upper and lower cases 13, the connecting body 17 that airtightly connects the internal section of J6, and the upper and lower cases 1
3. Coaxially pass the pages through the inside of J6 and the inner tube 15 of the lower case 16
A main valve 19 is fixed to the lower end of the piston rod 18, and a bottom valve 20 is fixed to the lower end of the inner cylinder 15.
The main valve 19 divides the oil chamber in the inner cylinder 15 into a chamber A above the main valve 19 and a chamber B below the main valve 19.
Further, the upper end of the reservoir chamber cl between the outer cylinder j4 and the inner cylinder 15 communicates with the upper end of the A chamber, and the lower end thereof communicates with the lower end of the B chamber. Further, a control rod 21 passes vertically through the center of the piston rod 18 [7], and the upper end 21a of this control rod 2J 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 the control rod 21 is provided with an orifice 2'lb that communicates with a communication hole 18b provided at the lower end of the piston rod 18 so as to communicate the A chamber and the B chamber. By rotation of the control rod 21, communication between the orifice 21b and the communication hole 18b of the lower end portion 18a of the piston rod is turned on and off.

The lower end of the piston rod 18, including the lower end of the control rod 21, the main valve J9, and the bottom pulp 2.
Details of the structure of 0 are omitted.

The relative vertical movement of the upper case 13 and lower case 16 is caused by the air spring caused by the air chamber 12, as well as by the upper and lower cases], 3
, upper and lower spring cases 13a' fixed to 16
, 16a. Brackets 16b and 16c fixed to the outer surface of the lower case 16 are used to fix the entire wheel support structure including the wheels that rotatably support the wheels. 10 so that it can move up and down. That is, the vehicle body is suspended by wheels and elastically supported so that it can move up and down.

A part of the peripheral wall of the air chamber 12 is provided with an opening 122I, and one end of a pneumatic pipe 23 that communicates the two accumulators with the air chamber 12 is connected to the opening D12a. . The other end of this pneumatic piping 23 is the renoid valve (the actuator) of the accumulator 2A.
2a, and this lunoid bulb 2a is electrically connected to a lead wire 3c from the controller 3.

As described above, this sononoid valve 2a is opened and closed by the output of the controller 3 to cause the air chamber 12 and the two accumulators to communicate at full speed or to separate, thereby decreasing or increasing the spring constant KR of the air spring.

The suspension of an automobile according to the present invention uses a spring means with a variable spring constant as described above, and controls the spring means according to changes in total acceleration to prevent sudden acceleration (including sudden start). K
By minimizing F,/KR, the ground contact force of the front wheels, which is weakened during sudden acceleration, can be maintained at a sufficient strength, ensuring reliable transmission of driving force at all times regardless of changes in acceleration. High response to sudden starts and accelerations 11
ffi can be realized.

[Brief explanation of drawings]

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 sectional view showing an example of a spring means used in the suspension of the present invention. 1.2...? Suspension la, 2a... Actuator IA, 2A... Accumulator 3... Controller 4...
・・・・・・・・・Speedometer 5・・・・・・・・・
...Acceleration sensor 12...Air chamber 1:3...Upper case 14...Outer tube 15...Inner cup 16.・・・・・・
...Lower case 18... Piston rod Fig. 1 (-/ Fig. 2 h

Claims (2)

[Claims] (1) In a front engine/front drive automobile, a spring means with a variable spring constant provided in parallel with a damper on at least one of the suspensions of the front and rear wheels, an adjusting means for completely changing the spring constant of the spring means, An acceleration sensor that detects sudden starts and sudden accelerations, and control that receives the output from this acceleration sensor and lowers the ratio of the spring constant of the front wheel suspension to the spring constant of the rear wheel suspension during sudden starts and sudden accelerations compared to normal times. An automobile suspension comprising a controller that inputs a signal to the adjustment means. (2) The automobile suspension according to claim 1, wherein the spring means is an air spring.