JPH06219338A - Cab active suspension - Google Patents

Abstract

(57) [Summary] [Purpose] Three points of the cabin (eg two points on both sides of the front, one in the middle of the rear)
The servomotor is controlled based on the vertical acceleration acting on the point), and the pushrod driven by the servomotor
The vertical movement of the cabin with respect to the vehicle frame is suppressed. [Structure] Air springs 16 and 16a are provided between the front and rear / right and left four corners of the bottom of the casing 2 and the vehicle frame 9, and a servo motor 23 is supported on the vehicle frame 9 adjacent to the air springs 16 and 16a. To do. Arm 25 connected to axis 24 of servo motor 23
The push rod 27 in the vertical direction, which is in contact with the bottom portion of the casing 2, is connected to the. The servo motor 23 is driven forward and backward by the output of the electronic control unit 20 based on the signals of the vertical acceleration sensor 19 arranged at the four corners of the cabin 2, and the air spring 1
The push rod 27 is provided with a drag force in the opposite direction of the expansion and contraction movement of 6, 16a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active suspension system for a cabin which suppresses vertical vibration of the cabin of a cabin type vehicle and improves riding comfort.

[0002]

2. Description of the Related Art As disclosed in Japanese Utility Model Laid-Open No. Sho 63-158481,
In a suspension system for a cabin, in which the four corners of the bottom of the cabin are supported on the vehicle frame by air springs, the amount of air in each air spring is adjusted by a leveling valve that operates in response to relative vertical displacement between the vehicle frame and the cabin. While supporting the cabin at a substantially constant height with respect to the vehicle frame, the high frequency vibrations due to road surface changes are suppressed from being transmitted from the vehicle frame to the cabin. However, in the above-described suspension system, the leveling valve operates after the height of the cabin changes with respect to the vehicle frame, so the responsiveness is poor, and when the vehicle accelerates or decelerates or turns, the cabin moves forward or backward or left or right. Can be greatly inclined to.

[0003]

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to control a servomotor based on vertical accelerations acting on four corners (or two points on both front sides and one rear intermediate point) of a cabin, It is an object of the present invention to provide an active suspension system for a cabin that suppresses vertical movement of the cabin with respect to a vehicle frame by a push rod driven by a servo motor.

[0004]

In order to achieve the above object, the structure of the present invention is such that springs are respectively provided between at least three points on the front and rear bottom portions of the cabin and the vehicle frame, and adjacent to each spring. Output of the electronic control unit based on the signal of the vertical acceleration sensor that supports the servo motor on the vehicle frame, contacts the vertical push rod vertically driven by the servo motor to the bottom of the cabin, and arranges the vertical acceleration sensor adjacent to each spring in the cabin. Thus, the servomotor is driven in the forward and reverse directions, and a drag force in the direction opposite to the expansion and contraction motion of the spring is applied to the push rod.

[0005]

According to the present invention, for example, when the car receives a thrust force when the vehicle gets over an obstacle on the road, the thrust force is detected by the vertical acceleration sensor, and the electronic control unit is based on the signal of the vertical acceleration sensor. The servo motor is driven by the output of, the push rod is lowered, and the lift of the cabin is suppressed. Conversely, when the cab is pulled down, the push rod rises and the sunk of the cab is suppressed. In this way, excessive vertical vibration of the cab (low frequency vibration)
Is suppressed by a push rod driven by a servo motor, and at the same time high-frequency vibrations from the car frame to the cabin are absorbed by the air springs, and even if the car frame vibrates up and down due to changes in the road surface, the cabin vibration is suppressed and the height is almost the same. Maintained at.

[0006]

1 is a side view of a vehicle equipped with an active suspension system for a cabin according to the present invention, and FIG. 2 is a rear view of a suspension mechanism for supporting a rear portion of the cabin on a vehicle frame. The vehicle frame 9 for suspending the front wheels 8 by a normal leaf spring or the like has the support plate 3 connected to the front end thereof, and the link 5 in the front-rear direction between the support plate 6 connected to the front end of the cabin 2 in the lateral direction. The tilt shaft 4 is connected to the pin 7, and an air spring 16 is interposed between the intermediate portion of the link 5 and the bottom frame 2a of the cabin 2. The rear end of the cabin 2 is supported on the floating frame 12, and the floating frame 12 and the cabin support frame 1
An air spring 16a is interposed between the air spring 16a and 0. More specifically, as shown in FIG. 2, the support plate 10a protruding outward from the side wall of the inverted U-shaped casing support frame 10 coupled to the vehicle frame 9,
The floating frame 12 is supported via the air spring 16. The air spring 16a is a piston 18 that projects upward from the support plate 10a.
And a floating frame 12, a rubber bellows is connected, and pressurized air is sealed inside the bellows.

A lateral rod 14 is connected by pins 13a and 15a between a support plate 13 projecting upward from an intermediate portion of the cabin support frame 10 and a support plate 15 projecting downward from an intermediate portion of the floating frame 12. . The lateral rod 14 allows the floating frame 12 to move up and down, but restricts the horizontal movement. The rear end portion of the bottom frame 2a is placed on the elastic seats 17 of the floating frame 12, and the left and right middle portions of the bottom frame 2a are locked to the middle portion of the floating frame 12 by a well-known cabling mechanism 30. It When servicing the engine, the cab 2 releases the cab lock mechanism 30 and is tilted forward around the tilt shaft 4. Such a structure is almost the same as that of the conventional air spring type suspension system.

According to the present invention, the servo motor 23 having a built-in speed reducer is supported on each support plate 10a, and the servo motor 2
Arm 2 connected to shaft 3 (accurately the output shaft of the reducer) 24
A push rod 27 is connected to the end of 5 by a pin 26 (preferably a universal joint). The push rod 27 projects upward and is connected to the floating frame 12 by a pin (preferably a universal joint). However, the push rod 27 need only be brought into contact with the floating frame 12 as long as it is guided and supported so as not to fall. Although not shown, the servo motors 23 are supported on the links 5 adjacent to the air springs 16 on both sides of the front end of the casing 2, and push rods 27 projecting upward from the servo motors 23 are pinned to the bottom frame 2a. Are connected by or are abutted so as not to fall.

In order to detect vertical accelerations acting on the four corners of the bottom frame 2a of the cabin 2, acceleration sensors 19 are provided at both ends of the floating frame 12, and similarly, both front end sides of the bottom frame 2a are also provided. An acceleration sensor 19 is provided. Each acceleration sensor 1
The signal No. 9 is applied to the electronic control unit 20, and the electronic control unit 20 calculates the control torque to be applied to each servo motor 23. The torque control unit 21 outputs the signal from the electronic control unit 20 and the feed back signal from the servo motor 23. The electric current corresponding to the deviation from the is supplied to the servo motor 23.

The electronic control unit 20 controls the servomotors on the left and right sides of the front part individually by the signals of the acceleration sensors 19 on both sides of the front end of the cabin 2, and the acceleration sensors 19 on both sides of the rear end.
The left and right servomotors 23 are also controlled by the average signal of the above.

Now, when the front wheel 8 rides on a convex portion of the road surface, etc., the thrust force applied to the four corners of the cabin 2 is detected by the acceleration sensors 19 and electronically controlled. The device 20 obtains the control torque required to cancel the thrust force based on the vertical acceleration, and the torque control unit 21 supplies the servo motor 23 with the current required to generate the control torque. When a current is supplied from the torque control unit 21 to the servo motor 23 so as to suppress the lifting of the cabin 2, the supporting force of the push rod 27 by each servo motor 23 becomes weak, and the servo motor 23 on the left side in FIG. Counterclockwise, right side servo motor 2
3 rotate clockwise, respectively, and allow push rod 27 to descend. Therefore, the air spring 16a contracts, the cabin 2 placed on the floating frame 12 sinks, and the lifting of the cabin 2 is suppressed. Thus, when an excessive push-up force or pull-down force acts on the casing 2, the servo motor 23 instantaneously rotates in the forward and reverse directions, the push rod 27 moves up and down, and the vehicle frame 9
The low-frequency vibration acting on the casing 2 is suppressed, and the high-frequency vibration is absorbed by the air springs 16 and 16a.

According to the present invention, the control torque applied to the servomotor 23 in response to the vibration input (acceleration detected by the acceleration sensor 19) acting on the four corners of the casing 4 from the vehicle frame 9 (the supporting force for the casing 27). Is determined based on the characteristic (control torque / vibration input) as shown in FIG. 3 corresponding to the frequency of the vibration input. And car frame 9
The ratio of the signal x2 actually output by the cab 2 to the vibration input x1 exerted on the cab 2, that is, the damping ratio (20 × l
The base number of og x2 / x1 log is 10), and the line 41 is shown in FIG.
As shown by, the excellent attenuation characteristics are exhibited in the frequency range of 1 to 10 Hz. That is, in the case of a cabinet that does not include the active suspension of the present invention, the frequency 1
Although resonating at -10 Hz, in the case of the cab equipped with the active suspension of the present invention, the vibration of the cab is effectively suppressed as indicated by the line 41.

In the above-described embodiment, the air spring is interposed between the vehicle frame and the cabin, but a similar metal spring can be used instead of the air spring to obtain substantially the same effect.

The push rod 27 can be moved up and down by a cam mechanism driven by the servo motor 23.

[0015]

As described above, according to the present invention, springs are respectively provided between at least three points on the front and rear bottoms of the cabin and the car frame, and the servo motor is supported on the car frame adjacent to each spring, and the servo motor is provided. The push rod in the vertical direction, which is driven vertically by the motor, is brought into contact with the bottom of the cabin, and the servo motor is driven forward and backward by the output of the electronic control unit based on the signal from the vertical acceleration sensor installed in the cabin adjacent to each spring. Since the pushing force is applied to the push rod by the direction opposite to the expansion and contraction movement of the spring, when the cab receives the thrust force, the thrust force is detected by the vertical acceleration sensor, and the electronic control unit based on the signal of the vertical acceleration sensor is used. The servo motor is driven by the output, the push rod descends, the lift of the cabin is suppressed, and when the pull force is applied to the cabin, the push rod rises. Sinking of the cab is suppressed. In this way, excessive vertical vibration (low-frequency vibration) of the cabin is suppressed by the push rod that is driven by the servo motor, and at the same time high-frequency vibration from the vehicle frame to the cabin is absorbed by the spring, and even if the vehicle frame vibrates vertically due to road surface changes. The vibration of the cab is suppressed and the cab is maintained at a substantially constant height.

According to the present invention, the push-rod is driven by the servo motor based on the vertical acceleration received by the cabin, and the vertical movement of the cabin is suppressed.
The responsiveness is excellent, and the supporting force that the push rod exerts on the cabin changes in proportion to the current of the servo motor, so that the operation is smooth and the cabin does not feel rugged, and a good riding comfort is obtained.

[Brief description of drawings]

FIG. 1 is a side view of a vehicle equipped with an active suspension system for a cabin according to the present invention.

FIG. 2 is a rear view of the active suspension system at the rear of the cabin.

FIG. 3 is a diagram showing frequency characteristics of a control torque applied to a servomotor of the active suspension system.

FIG. 4 is a diagram showing vibration damping characteristics of a cabin equipped with the active suspension device and a cabin not equipped with the active suspension device.

[Explanation of symbols]

2: Cab 9: Vehicle frame 16, 16a: Air spring 1
9: Vertical acceleration sensor 20: Electronic control device 23: Servo motor 24: Axis 25: Arm 27: Push-rod

Claims (1)

[Claims] 1. A vertical direction in which springs are respectively provided between at least three points on the front and rear bottoms of the cabin and a vehicle frame, and a servomotor is supported on the vehicle frame adjacent to each spring, and is vertically driven by the servomotor. Push the push rod to the bottom of the cab, and drive the servo motor forward and backward by the output of the electronic control unit based on the signal from the vertical acceleration sensor installed in the cab adjacent to each spring. An active suspension system for a cab, which is characterized in that the drag force of the above is applied to the push rod.