GB2025572A

GB2025572A - Fluid apparatus for actively controlling vibration of a vehicle

Info

Publication number: GB2025572A
Application number: GB7923999A
Authority: GB
Original assignee: Hitachi Ltd
Current assignee: Hitachi Ltd
Priority date: 1978-07-14
Filing date: 1979-07-10
Publication date: 1980-01-23
Also published as: FR2430860B1; GB2025572B; ZA793455B; AU4886779A; AU513099B2; JPS5511954A; JPS6234580B2; FR2430860A1

Abstract

A vehicle body is resiliently supported by passive springs and dampers and double acting piston-cylinder air units, supply and exhaust of air to which is controlled in response to vibrations of the vehicle in such a way that the vibrations are damped. At the front of the vehicle body, there are 3 of these units, 2f, 2'f and 3f, one of which responds to horizontal vibrations and the other two of which respond to vertical vibrations. At the rear of the body there are 3 similar units. The signals are obtained from accelerometers. <IMAGE>

Description

SPECIFICATION Apparatus for controlling vibration of a vehicle This invention relates to an apparatus for controlling vibrations of a vehicle, especially to a vehicle vibration controlling apparatus for attaining a comfortable ride.

A prior art and this invention will be described with reference to the accompanying drawings in which: Figure 1 shows in block diagram the control circuit of a conventional apparatus for controlling vibrations of a vehicle; Figure 2 shows the control circuit of an apparatus for controlling vibrations of a vehicle, as an embodiment of this invention; and Figures 3 and 4 show respectively the control circuits of apparatuses for controlling vibrations of a vehicle, as other embodiments of this invention.

According to a typical example of a system for controlling vibrations of a vehicle, an air spring is used together with ordinary springs and a damping mechanism such as a dash pot and the internal pressure of the air spring is controlled in accordance with the vibrational acceleration of the car body processed as a control input. Such a conventional system is still under development with the aid of a basic model as shown in Figure 1. In Figure 1, reference numeral 1 designates a car body and numeral 2 a chassis, the chassis 2 being coupled to a vibrator 11. Numeral 3 indicates a spring for supporting the car body 1; 4 a dash pot; and 5 an air spring for control.The output of a vibrational acceleration detector 6 for detecting the vibration of the car body 1 is sent through a compensating circuit 7 and a servo-amplifier 8 to a torque motor 9, which actuates and controls an air pilot valve 10to control the internal pressure in the air spring 5. In this system, the spring 3 and the dash pot 4 serve to maintain the reference level of the car body 1 and also possible to absorb, to a certain extent, vibrations of the body 1, while the air spring 5 plays only an auxiliary role of absorbing vibrations of the car body 1. Accordingly, the consumption of the air used to actuate the air spring 5 can be economized. Further, this system is simple and therefore can be fabricated inexpensively and also have a high resistivity to dust contamination. In these respects, this vibration control system is advantageous.However, the air to actuate the air spring 5 is consumed even when the air spring 5 respond to the horizontal or lateral vibrations, that is, even when the air spring 5 is laterally deformed. In addition, since the air spring 5 used in this system is of mono-chamber type, that is, has only one air chamber and hence is of single actuation type, the response characteristics are poor and, since a higher pressure cannot be applied to the air spring, the size of the air chamber must be large. Further, the change in the pressure of the air spring 5 during the vibration control operation will cause the change in the spring constant of the air spring 5 in the direction perpendicular to the control direction, i.e. vertical direction, so that the vibration absorbing characteristic in the perpendicular direction, i.e. horizontal direction is adversely affected.These facts are drawbacks of the conventional system. In order to reduce the vibrations of the car body as a whole, it is necessary, in view of vibrations in more than one degree of freedom, to suitably locate the control apparatus so as to make the best use of the air source for the improvement of the vibration absorbing characteristics.

The object of this invention is to reduce vibrations of the vehicle to a great extent by using, together with springs and damping mechanisms, air cylinders of multi-chamber type having an excellent response characteristic, a simple structure, a high resistivity to dust contamination with an economical consumption of driving air and by controlling the operations of the air cylinders of multi-chamber type in accordance with the vibrational acceleration of the vehicle used as the control input.Further, according to this invention, multi-chamber air cylinders are provided for suppressing the vertical and horizontal vibrations of the vehicle, the air cylinders for the vertical vibrations being located as far from the center line of the vehicle outward as possible at the transverse section of the vehicle and the air cylinder for the horizontal vibrations being disposed in the center of the vehicle at the transverse section of the vehicle.In the case of a train, two successive chassis of the vehicle are equipped with the same sets of control sections and the yawing vibrations peculiar to train vehicles are controlled mainly by the muiti-chamber air cylinders for suppressing the horizontal vibrations, provided on the two chassis while the tossing, pitching and rolling vibrations are controlled mainly by the air cylinders for the vertical vibrations, whereby, the vibrations of the whole train can be considerably reduced.

In a preferred embodiment of this invention, vibration of the lower end of a spring is detected and, only when the detected signal exceeds a preset value, the control of vibrations of a vehicle is performed.

Now, the embodiments of this invention will be described with the aid of Figures 2 to 4. In Figure 2, along with front end springs lf and 1 tf provided between a car body and a car body supporting member such as chassis are provided air cylinders 2f and 2/f of multi-chamber type or double actuation type (hereafter referred to as multi-chamber air cylinders) for absorbing vertical vibrations at the front end of the vehicle and a multi-chamber air cylinder 3f for absorbing horizontal vibrations at the front end of the vehicle. As shown, the multichamber air cylinders 2f and 2'f are located as far from the centre line of the vehicle outward as possible while the multi-chamber air cylinder 3f is disposed in the center of the car body.The reference symbol a3 designates the distance between the center of the vehicle and the position at which the air cylinder 2f (or 2/f) is disposed. The vertical vibrational acceleration, the rotary angular acceleration and the horizontal vibrational acceleration at the front 4f of the car body are detected respectively by a vertical vibrational accelerometer 5 an angular accelero meter 5fe and a horizontal vibrational accelerometer 5,, disposed at the front 4 f of the car body. The outputs of the accelerometers S and 5fO are sent to a compensating circuit 6fz to perform the gain and phase compensations.The output of the compensating circuit 6fz is amplified by a servo-amplifier 7fz and thereafter the amplified electrical signal is converted to a pneumatic signal by means of a flapper 9 actuated by an electromagnet 8 and of nozzles 10 and 10'. The internal pressure of the multi-chamber air cylinder 2, is controlled by a servo-valve 1 2z comprising airpilotvalves 11 and 11' controlled by the pneumatic signal.

The outputs of the accelerometers 5fz and S, are sent also to a compensating circuit 6, and in like manner the multi-chamber air cylinder 2/f is controlled. A correction is made for the outputs of the accelerometers S,, and 5fO by means of correction elements a3, and a'3f to obtain a true vertical vibrational acceleration to be controlled by the air cylinders 2f and 2/f. The compensation circuit 6',,, the servo-amplifier 7'," and the servo-valve 12', are of the same kind as those shown as 6,,, 7f, and 12,, respectively.

The output of the accelerometer S,, is sent through a compensating circuit 6f, and a servo-amplifier 7," to a servo-valve 12,, to control the internal pressure of the multi-chamber air cylinder 3f. The reference symbols Zof and Z'0, and Yof andY'0, designate vertical and horizontal rail track displacements and hence represent sources of vibrations applied to the wheels of the vehicle.

Together with rear end springs lrand 1',, multichamber air cylinders 2r and 2', are provided for absorbing the vertical vibrations at the rear 4, of the vehicle and a multi-chamber air cylinder 3rfor absorbing the horizontal vibrations at the rear 4, of the vehicle. The multi-chamber air cylinders 2, and 2'rare located, as shown, as far from the center line of the car body outward as possible and the multi-chamber air cylinder 3, is disposed in the center of the car body. The outputs of the vertical vibrational accelerometer 5fz and the angular accelerometer 5f6 at the front 4f of the vehicle are sent to a compensating circuit 13z to compensate the gains, phases and dead times thereof.The output of the compensating circuit 13z is supplied to a servoamplifier 7,. The vertical vibrational acceleration, the rotary angular acceleration and the horizontal vibrational acceleration at the rear 4, of the car body are detected respectively by a vertical vibrational accelerometer 5,,, an angular accelerometer 5,(3 and a horizontal vibrational accelerometer Sry disposed at the rear 4, of the car body. The outputs of the accelerometers 5,, and 5,e are supplied to a compensating circuitS,, to compensate the gains and phases thereof.The output of the compensating circuit 6,, is supplied to a servo-amplifier 7,. The output of the servo-amplifier 7,,, which receives the outputs of the compensating circuits 13, and 6,,, is sent to a servo-valve 14, which controls the internal pressure of the multi-chamber air cylinder 2,just as in the case of the control of the air cylinder 2f.

The outputs of the accelerometers 5fz and 5fO at the front 4f of the car body are supplied through a compensating circuit 13'z to a servo-amplifier 7',, and the outputs of the accelerometers 5, and 5r6 at the rear 4, of the car body are supplied through a compensating circuitS',, also to the servo-amplifier 7',,. The output of the servo-amplifier 7',, is supplied to a servo-valve 14',, which controls the internal pressure of the multi-chamber air cylinder 2',.

The outputs of the accelerometer S,, and the accelerometerS,, are both supplied to a servo amplifier 7,, respectively through compensating circuits 13y and 6ry. The output of the servo-amplifier 7ry is supplied to a servo-valve 14,, which controls the internal pressure of the multi-chamber air cylinder 3r. For the following vehicles, if there is any connected, the same control system as provided at the rear 4, of the above described vehicle may be employed. When the flapper 9 stops the nozzle 10 in the servo-valve 1 2z for the air cylinder 2f, the backpressure of the nozzle 10 increases to urge the air pilot valve 11 to open so that the air pressure in the lower chamber of the multi-chamber air cylinder 2f increases.Accordingly, the backpressure of the nozzle 10' decreases to open the evacuating port of the pilot valve 11' so that the air pressure in the higher chamber 16f of the multi-chamber air cylinder 2f decreases. As a result, the difference between the pressures in the lower and higher chambers 15f and 16, causes the piston 17,to move upward. The vertical acceleration of the piston 17,, i.e. the vertical acceleration of the left front of the car body, is detected by the accelerometer S,, and S,o and the detected signal is fed back to control the movement of the piston 17f in such a manner that the vertical acceleration of the car body vanishes.The accelerometers 5,, 5re and 5, at the rear 4, of the car body or the preview control input lines 18z, 18,, and 18'z connecting the front with the rear control section may be omitted to simplify the apparatus shown in Figure 2. In each of such cases, the control characteristic is slightly degraded, but the slight degradation can well be compensated by the resultant decrease in cost.

Figure 3 shows another embodiment of this invention, i.e. an apparatus for controlling the vibrations of a vehicle. The difference in this embodiment from the embodiment shown in Figure 2 is that the accelerometers Sf2, 5fe and S,,, at the front of the car body are replaced by a vertical vibrational accelerometer 20for an angular accelerometer 2O, and a horizontal vibrational accelerometer 20fy as control input means provided under the bottom 19f of the front spring, the chassis frame 19fl or the axle box 19,2 and that the accelerometers 5,,, 5,, and 5, at the rear of the car body are replaced by a vertical vibrational accelerometer 20rz, an angular accelerometer 20,, and a horizontal vibrational accelerometer 20ry as control input means provided under the bottom 19, of the rear spring, the chassis frame 19, or the axle box 19,2' The other sections of the control system are the same in both the embodiments. Therefore, according to this embodiment shown in Figure 3 which responds in detection faster than the apparatus for detecting the vibrations of the car body itself, the delay of the operation of the servo-valve can be compensated. The accelero meters 20,,, 20r0 and 20ray provided under the bottom 1 9r of the rear spring may be omitted or the preview control input lines 21z, 21y and 21'2 connecting the bottom 19f of the front spring with the bottom 1 9r of the rear spring may be eliminated. Moreover, the compensating circuits 6t 6fry, 6,' 13z, 13y, 13'z, 6,,, 6," and 6',, may be replaced buy a microcomputer to adopt a software servo-system.

Figure 4 shows still another embodiment of this invention, i.e. an apparatus for controlling the vibrations of a vehicle. This embodiment is produced by adding the following parts to the embodiment shown in Figure 2. In this embodiment, the outputs of a vertical and a horizontal vibrational accelerometers 22z and 22y provided under the bottom 19f of the rear spring are sent respectively through lowpass filters 23z and 23y to level comparators 24z and 24y. When the compared levels exceed preset levels, relays 25z and 25y start their operation to initiate the control of vibrations. Accordingly, the desired degree of comfortable ride can be attained and that with a smaller consumption of driving air.

As described above, according to this invention which uses the multi-chamber air cylinders, the difference between the air pressures in different chambers acts upon the piston so that the speed of the piston moving is about twice as large as that attainable with the conventional mon-chamber air cylinder. As a result, the operational delay can be eliminated, the response characteristics can be improved, the controllability of the vibrations of a vehicle can be enhanced so that the vibrations of the car body can be suppressed to a great extent.

Further, since the use of cylinders allows a high speed movement only in fixed directions, the controllability of the vertical and horizontal vibrations of the car body can be improved. This also adds to the effective suppression of the vibrations of the car body. Also, the high capability against pressure permits the reduction of size of the apparatus.

Moreover, the adoption of the arrangement of the cylinders designed in view of the whole vibration modes of the vehicle train further reduces the vibrations to a considerable extent so that the deterioration of the rail track can be minimized and that the expense for the maintenance of railroads can be considerably economized.

Claims

1. An apparatus for controlling vibrations of a vehicle in which the car body is supported on a chassis by springs and damping mechanisms, com prising multi-chamber air cylinder means, detector means for detecting the vibrations of said vehicle, and control means for controlling the operations of said multi-chamber air cylinder means in accordance with the outputs of said detector means.

2. An apparatus as claimed in Claim 1, wherein said air cylinder means comprises at least two first multi-chamber air cylinders for suppressing the vertical vibrations of said vehicle and at least one second multi-chamber air cylinder for suppressing the horizontal vibrations of said vehicle, and said detector means comprises at least one first detector for detecting the vertical vibrations and at least one second detector for detecting the horizontal vibrations, said control means controlling the operations of said first and second air cylinders in accordance with the outputs of said first and second detectors, respectively.

3. An apparatus as claimed in Claim 2, wherein said first air cylinders are located at two points near the lateral sides of said vehicle while said second air cylinder is located in the center of said vehicle.

4. An apparatus as claimed in Claim 1, further comprising comparator means for comparing the outputs of said detector means with predetermined settings and for starting the operation of said control means when said outputs of said detector means exceed said settings.

5. An apparatus as claimed in Claim 1,wherein said air cylinder means comprises at least two first multi-chamber air cylinders for supressing the vertical vibrations of said vehicle and at least one second multi-chamber air cylinder for supressing the horizontal vibrations of said vehicle, disposed at each of the front end and the rear end of the vehicle, and said detector means comprises at least one first detector for detecting the vertical vibrations and at least one second detector for detecting the horizontal vibrations, disposed at each of the front end and the rear end of the vehicle, and said control means comprises a front air cylinder controlling device for controlling the operations of said first air cylinders and said second air cylinder disposed at the front end in accordance with the outputs of said first detector and second detector disposed at the front end respectively and a rear air cylinder controlling device for controlling the operations of said first air cylinders and said second air cylinder disposed at the rear end in accordance with the outputs of at least said first detector and second detector disposed at the rear end respectively.

6. An apparatus as claimed in Claim 5, wheren said rear air cylinder controlling device controls the operations of said first air cylinders and said second air cylinder disposed at the rear end in accordance with the outputs of both said first detectors disposed at front and rear ends and both said second detectors disposed at front and rear ends respectively.

7. An apparatus as claimed in Claim 1, wherein said air cylinder means comprises at least two first multi-chamber air cylinders for suppressing the vertical vibrations of said vehicle and at least one second air cylinder for supressing the horizontal vibrations of said vehicle, disposed at each of the front end and the rear end of the vehicle, and said detector means comprises at least one first detector for detecting the vertical vibrations and at least one second detector for detecting the horizontal vibrations, disposed at the front end of the vehicle, and said control means comprises a controlling device for controlling the internal air pressures of said first air cylinders at the front and rear ends and said second air cylinders at the front and rear ends in accordance with the outputs of said first detector and second detector respectively.

8. An apparatus for controlling vibrations of a vehicle constructed and arranged to operate sub stantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.