JP3011005B2 - Vehicle suspension device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suspension device using an air spring in a heavy vehicle such as a bus or a truck which absorbs vertical and longitudinal vibrations generated when the vehicle runs.

[0002]

2. Description of the Related Art Conventionally, when a vehicle travels, vertical vibrations and impacts are applied to the wheels due to road conditions, load of a load, and the like, and the vibrations and impacts cause occupants of the vehicle to feel uncomfortable. It also damages the cargo.

In order to alleviate this problem, a cushioning member is used in a vehicle suspension device. However, in a heavy vehicle such as a bus or a truck, an air compression utilizing air compression having excellent vibration absorption is used. Springs may be used. FIG. 4 shows a mechanism of a vehicle suspension device using an air spring, which will be described below.

In a vehicle suspension system using this air spring, an air spring 2 and a shock absorber 6 are provided in parallel between a vehicle body 1 and an axle lever 4a provided on an axle 4. The shock absorber 6 supports one end of the axle lever 4a, and the air spring 2 has a piston 5 mounted below it to support the center of the axle lever 4a.

The axle lever 4a moves up and down together with the axle 4 supporting the wheels 3 by the action of a link that allows the axle 4 not shown to move up and down. A connecting rod 7 is attached to the other end of the axle lever 4a, and a vehicle height adjusting valve 8 is attached to the connecting rod 7. The height adjustment valve 8 includes a compressed air source and an air spring 2.
The connecting rod 7 is moved up and down by the up and down movement of the axle lever 4a, and the up and down movement of the connecting rod 7 opens and closes the vehicle height adjusting valve 8 to send high-pressure air into the air spring 2 or to reduce the pressure in the atmosphere. By keeping the vehicle body 1 at a substantially constant height irrespective of a change in weight of the vehicle body 1, vibration and shock are absorbed.

[0006] The suspension device employing the above air spring has a low spring constant and good vibration absorption, but the air spring expands and contracts due to a change in the vehicle load such as a stop of the vehicle or a curve turn, and the vehicle becomes larger vertically. The amount of swaying balance,
The roll angle and the pitch angle, which are inclined, increase.

[0007] Therefore, as a means to solve this,
The hydraulic / pneumatic suspension apparatus using hydraulic / pneumatic pressure has come to be used. The configuration is shown in FIG. 5 and will be described below.

This hydraulic / pneumatic suspension device has wheels 1
An actuator 11 (strut cylinder) for buffering the vertical movement of the vehicle body 1 (not shown) is provided above the axle 4 supporting the vehicle body 0, and an accumulator supported on the vehicle body 1 via a damper 13 formed of an orifice on the actuator 11 12 (gas spring) are provided.

A hydraulic source 16 is connected to a hydraulic circuit below the accumulator 12 via an electromagnetic valve 15, and a control circuit 14 is connected to the electromagnetic valve 15. And
By opening and closing the electromagnetic valve 15 under the control of the control circuit 14, the hydraulic pressure from the hydraulic pressure source 16 is introduced into the actuator 11 and the accumulator 12, cut off or discharged,
The roll and pitch angle of the vehicle body are kept low by the expansion and contraction of the actuator 11 and the operation of the accumulator 12 under this hydraulic pressure.

[0010] The hydraulic and pneumatic suspension devices include:
Japanese Patent Application Laid-Open Publication No. 64-52919 discloses a vehicle suspension according to the present applicant's application.
An air suspension mechanism according to the present applicant's application described in Japanese Patent Application Laid-Open No. 15904 is known.

[0011]

In such a control type hydraulic / pneumatic suspension device, the roll and pitch angle can be suppressed low by the expansion and contraction of the actuator due to the supply and discharge of hydraulic pressure, but the cylinder of the actuator and Depending on the friction of the piston, it is difficult to attenuate high-frequency vibration having a short cycle.

Further, the amount of oil supplied to the accumulator for acting as a spring increases, and the energy consumption increases. The present invention solves the above-mentioned problems of the conventional hydraulic pneumatic suspension device of the conventional type, and suppresses a posture change based on an increase in a roll and a pitch angle without impairing the vibration insulation of an air spring. The purpose is to reduce the energy consumption required for this.

[0013]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above-mentioned object, and in a vehicle suspension device having an air spring provided between a vehicle body and an axle, pressure is applied from upper and lower chambers of a piston body. Lateral acceleration detecting means for arranging a double-acting hydraulic actuator in series with the air spring, connecting a hydraulic valve for opening and closing hydraulic pressure to the double-acting hydraulic actuator, and detecting a lateral acceleration on the vehicle body. And longitudinal acceleration detecting means for detecting longitudinal acceleration, based on detection signals of the lateral acceleration detecting means and the vertical acceleration detecting means, the double-acting type required to reduce the amount of expansion and contraction of the air spring. The amount of expansion / contraction stroke of the hydraulic actuator is calculated and the calculated value is used as a command stroke, and the difference between the command stroke and the detected current stroke is calculated. Characterized in that connecting the control means for opening and closing the hydraulic valve to the hydraulic valve in accordance with the.

[0014]

According to the present invention, the amount of expansion / contraction stroke of the double-acting hydraulic actuator required to reduce the amount of expansion / contraction of the air spring based on the detection signals from the lateral acceleration detecting means and the vertical (longitudinal) acceleration detecting means. Is calculated as the command stroke, and the hydraulic valve is opened and closed according to the difference value between the command stroke and the detected current stroke, thereby adjusting the expansion and contraction of the double-acting hydraulic actuator, By reducing the amount of spring expansion and contraction,
The pitch angle can be absorbed.

Further, the unnecessary action of the double-acting hydraulic actuator is suppressed, and the roll, pitch angle,
In addition, a resonance effect does not occur, the energy consumed for performing the operation more than necessary is reduced, and the left and right inclination and the front and rear inclination of the vehicle body do not occur.

Further, the air spring enhances the absorbency of vibration by utilizing the low spring constant of the air spring.

[0017]

Next, an embodiment of the present invention will be described with reference to FIGS.
This will be described below. In this embodiment, an axle lever 4a is provided on an axle 4 supporting a wheel 3, and one end of the axle lever 4a is supported by a shock absorber 6 supported on the vehicle body 1, and
A double-acting hydraulic actuator 20 is mounted at the center of the a. An air spring 2 provided between the double-acting hydraulic actuator 20 and the vehicle body 1 supports the center of the axle lever 4a.

A stroke length sensor 21 is connected between the axle lever 4a and the arm 22 supported by the double-acting hydraulic actuator 20, and the stroke of the vertical movement of the axle 4 caused by the vibration of the wheel 3 is determined by the stroke length. The detection can be performed by the sensor 21.

The connecting rod 7 is connected to the arm 22, and a vehicle height adjusting valve 8 is provided at an end of the connecting rod 7. The vehicle height adjusting valve 8 is connected to a high-pressure air source and is connected to the air spring 2.
The height of the air spring 2 is adjusted by opening and closing the vehicle height adjusting valve 8 by the vertical movement of the connecting rod 7.

The double-acting hydraulic actuator 20 is
An upper chamber 20a and a lower chamber 20b for introducing hydraulic pressure across the piston body 23 are provided.
An electromagnetic valve 25 for switching the hydraulic pressure is provided between b and the hydraulic pressure supply source 24 that supplies the hydraulic pressure. A control circuit 28 is connected to the electromagnetic valve 25.

The vehicle body 1 has a longitudinal acceleration sensor 26 for detecting longitudinal (longitudinal) acceleration when a brake is applied or a sudden start is made, and a lateral acceleration generated when a vehicle turns a curve. A lateral acceleration sensor 27 is provided, and both sensors 26 and 27 are connected to a control circuit 28.

The acceleration detected by the longitudinal acceleration sensor 26 and the lateral acceleration sensor 27 and the stroke length of the axle 4 detected by the stroke length sensor 21 provided for each wheel 3 are input to a control circuit 28, and the output thereof is used as an electromagnetic signal. By operating the valve 25, the upper chamber 20 of the double-acting hydraulic actuator 20 is operated.
a, or selectively supplies or shuts off the hydraulic pressure to the lower chamber 20b.

The control circuit 28 comprises an input circuit 30, a command stroke calculation circuit 31, a stroke difference calculation circuit 32, and an output circuit 33, as shown in FIG. The input circuit 30 includes a lateral acceleration sensor 27, a longitudinal acceleration sensor 2
6. A circuit for receiving the output of each stroke length sensor 21. The command stroke calculation circuit 31
The command stroke is calculated based on the input from the acceleration sensor 7 and the longitudinal acceleration sensor 26.

The stroke difference calculation circuit 32 calculates the difference between the command stroke calculated by the command stroke calculation circuit 31 and the stroke detected by each stroke length sensor 21 for each stroke length sensor 21. Based on the calculation of the stroke difference calculation circuit 32,
A calculation value as a command stroke is obtained, and the calculated value is output to an electromagnetic valve 25 provided for each double-acting hydraulic actuator 20 in accordance with a difference value between the command stroke and the detected current stroke.

Next, the operation will be described with reference to the flowchart shown in FIG. Starting in step S1, the lateral acceleration x detected by the lateral acceleration sensor 27 in step S2
Is read through the input circuit 30 from the longitudinal acceleration y detected by the longitudinal acceleration sensor 26 in step S3.

Next, the weight of the vehicle and other specification data a, b, c, d which have been input to the control circuit 28 in advance.
Based on the lateral acceleration x and longitudinal acceleration y read in steps S2 and S3, the command strokes S1R, S2R, S3R and S4R for each stroke length sensor 21 are calculated by the command stroke circuit 31 in step S4 according to the following equations. Calculate.

S 1 R = ax + by S 2 R = −ax + by S 3 R = cx + dy S ₄ R = −cx + dy Further, in step S 5, strokes S _{1 to} S ₄ detected by the stroke length sensors 21 for each double-acting hydraulic actuator 20 are input to the input circuit 30. read through, a difference ΔS ₁ ~ΔS ₄ between the stroke S ₁ to S ₄ of the command stroke S1R~S4R and each stroke length sensor 21 at each stroke difference calculation circuit 32 in step S6, is calculated by the following equation.

ΔS ₁ = S ₁ R−S ₁ ΔS ₂ = S ₂ R−S ₂ ΔS ₃ = S ₃ R−S ₃ ΔS ₄ = S ₄ R−S ₄ Then, in step S 7, each of the electromagnetic valves is output from the output circuit 33 based on the above calculation result. Stroke difference Δ to 25
It outputs drive currents I _{1 to} I ₄ proportional to S _{1 to} ΔS ₄ .

In this manner, the difference between the current amount of expansion and contraction of the double-acting hydraulic actuator 20 and the stroke amount required for each double-acting hydraulic actuator 20 is fed back to operate the electromagnetic valve 25, The combined expansion and contraction amount of the air spring 2 and the double-acting hydraulic actuator 20 can be controlled.

Therefore, the combined expansion and contraction amount can be reduced as compared with the case where only the air spring 2 is used. Therefore, the roll and pitch angle of the vehicle body are reduced, the posture change is reduced, and the energy consumption required for this is reduced. The reduction can be achieved.

[0031]

As described above, the present invention provides a double-acting hydraulic actuator which can be extended and contracted in series with an air spring, and further comprises a lateral acceleration of a vehicle body, a longitudinal acceleration which is front and rear, and each Detects the stroke amount of the dynamic hydraulic actuator, and based on the detection results, calculates and feeds back by the control means, outputs it to the electromagnetic valve, and controls the double-acting hydraulic actuator, thereby suppressing the roll and pitch angle. It is.

In particular, since the control is performed for each double-acting hydraulic actuator and the attitude control is performed in a remarkably advanced state, it is possible to improve the steering stability and to improve the characteristics of the air spring, which is excellent. Without compromising ride comfort,
It also helps reduce driving fatigue.

Further, since the double-acting hydraulic actuator is not provided with an accumulator, it has the effect of reducing the power required to generate hydraulic pressure for driving the double-acting hydraulic actuator and suppressing the deterioration of fuel consumption. is there.

[Brief description of the drawings]

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

FIG. 2 is a control circuit diagram of the above.

FIG. 3 is a flowchart of the control circuit.

FIG. 4 is a configuration diagram of a conventional suspension using an air spring.

FIG. 5 is a configuration diagram of a conventional hydraulic / pneumatic suspension.

[Explanation of symbols]

 Reference Signs List 1 body 2 air spring 4 axle 20 double-acting hydraulic actuator 21 stroke length sensor 23 piston body 25 electromagnetic valve (hydraulic valve) 26 longitudinal acceleration sensor (longitudinal acceleration detecting means) 27 lateral acceleration sensor (lateral acceleration detecting means) 28 control circuit 31 Command stroke calculation circuit 32 Stroke difference calculation circuit 33 Output circuit

Claims (1)

(57) [Claims] 1. A suspension device for a vehicle in which an air spring is provided between a vehicle body and an axle, a double-acting hydraulic actuator capable of applying pressure from upper and lower chambers of a piston body is arranged in series with the air spring. A hydraulic valve for opening and closing hydraulic pressure is connected to the double-acting hydraulic actuator, and the vehicle body is provided with lateral acceleration detecting means for detecting lateral acceleration and longitudinal acceleration detecting means for detecting longitudinal acceleration. Based on the detection signals of the acceleration detecting means and the longitudinal acceleration detecting means, the amount of expansion / contraction stroke of the double-acting hydraulic actuator required to reduce the amount of expansion / contraction of the air spring is calculated, and the calculated value is used as the command stroke. A control means for opening and closing the hydraulic valve according to a difference value between the command stroke and the detected current stroke is provided to the hydraulic valve. A suspension device for a vehicle, wherein the suspension device is connected.