JPH0769030A - Suspension device for tractor - Google Patents

Abstract

PURPOSE:To prevent breakage or the like beforehand by communicating hydraulic pressure reactive actuators of a suspension device with an oil tank through control valves when a tractor travels by itself, and eliminating elongation directional force from being applied to an air spring device. CONSTITUTION:When a tractor turns, for example, right, pressure oil is supplied to a lower pressure chamber of a left side hydraulic pressure reactive actuator 54, and a lower pressure chamber of a right side hydraulic pressure reactive actuator 54 is communicated with an oil tank 72, and as a result, roller displacement when the tractor turns right is restrained by a difference in pushing-up force between the left and right actuators 54. In this case, when the tractor travels in itself, a changeover switch 70 is switched, and left and right control valves 64L and 64R are fixed respectively to a second switching position. Thereby, the left and right actuators 54 are communicated with the oil tank 72, and are substantially put under atmospheric pressure, and unreasonable hydraulic pressure is eliminated from acting on an air spring device 34, so that breakage or the like of an air bellows 42 can be surely prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tractor suspension device for pulling a trailer.

[0002]

2. Description of the Related Art Conventionally, a vehicle suspension device including an air spring device for controlling a vehicle height and a hydraulic active suspension device having a hydraulically responsive actuator that suppresses vibration of a vehicle body, particularly roll displacement, is disclosed in, for example, Japanese Unexamined Patent Publication (Kokai) No. It is disclosed in Japanese Patent Publication No. -85125.

The hydraulic active suspension system in the above proposed suspension system includes a left and right hydraulically-actuated actuators each comprising a hydraulic cylinder interposed between a vehicle body and an axle, and a control valve for controlling each hydraulically-actuated actuator. The control valve responds to the output signal of the rocking state detection device such as a lateral acceleration sensor and supplies the working pressure oil from the pressure oil source to either the left or right hydraulically responsive actuator to roll the vehicle body. Is to suppress. Further, an accumulator or a gas spring is connected to the working pressure chamber of the hydraulically-actuated actuator via an orifice or a throttle valve in order to damp vibrations in the relatively high unsprung resonance frequency range from the road surface side.

[0004]

An air spring device for adjusting the vehicle height as described above and a hydraulic active suspension device having a hydraulically responsive actuator for suppressing swinging of the vehicle body, particularly roll displacement, are provided in parallel. When the suspension device is applied to a rear shaft suspension device in a tractor, a special problem that does not usually occur in a passenger car, which is the main application target of the above-mentioned proposed invention, occurs.

That is, the load acting on the rear shaft of the tractor changes greatly between when the trailer is being pulled and when the trailer is being pulled, and when the trailer is not being pulled, and in the case of a medium-sized tractor, for example, The load of the rear axle when the trailer of a predetermined load weight is connected may reach several times the load of the rear axle when the vehicle is a single vehicle. Therefore, when a single vehicle is used, even if the pressure level of the operating pressure oil of the hydraulic active suspension device is controlled to a low level to reduce it to the minimum pressure of the gas spring, the load generated by the hydraulically responsive actuator against the small load acting on the rear shaft In the worst case, when the air spring devices that are excessively arranged and are juxtaposed are pushed up to the extension side, the rubber air bellows may be damaged, and even if the air bellows is not immediately damaged, the durability is impaired. Further, as the air spring device is fully extended as described above, the posture of the entire tractor becomes a nose dive state in which the rear part is lifted and the front part is lowered, which may cause a driver to feel uncomfortable or anxious. is there.

In view of this, the present invention focuses on the problem of the suspension device for a tractor in which the air spring device and the hydraulic active suspension device are arranged side by side, and the hydraulic response acting on the air spring device when the single vehicle is running without pulling the trailer. By eliminating the load generated by the actuator,
Preventing damage to the air spring device, improving durability, and preventing the posture of the entire tractor from becoming a nose dive state when traveling in a single vehicle, and eliminating discomfort or anxiety of the driver. It is intended.

[0007]

SUMMARY OF THE INVENTION The present invention was devised to achieve the above object, in which a rear shaft of a tractor is provided with an air spring device for controlling a vehicle height and a hydraulically actuated vehicle for controlling the vibration of a vehicle body. In a vehicle supported by a chassis frame through a hydraulic active suspension device having an actuator, the hydraulically-actuated actuator, when the single vehicle is traveling without the tractor pulling the trailer,
The present invention proposes a suspension device for a tractor, which is constantly communicated with an oil tank via a control valve that controls the operation thereof.

[0008]

With the above-described structure of the present invention, when the tractor is traveling in a single vehicle, the hydraulically responsive actuator of the hydraulic active suspension device is communicated with the oil tank through the control valve. Force is not applied, the air bellows of the air spring device is not damaged or the durability is not deteriorated, and the air spring device is fully extended so that the vehicle body is in the forward leaning or nose dive posture. Is prevented.

[0009]

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. In the drawings, reference numeral 10 denotes a chassis frame of a tractor, which includes a pair of left and right side rails 12 that extend in the front-rear direction of the vehicle body and have a thin sectional shape, and side rails 12 that extend in the vehicle width direction. A plurality of cross members 14 fixed to the rail 12 by rivets, bolts, etc.
It is equipped with

Below the rear part of the chassis frame 10,
Rear axle 16 with rear wheels (not shown) attached to the widthwise end
A rear axle housing 18 that accommodates the rear axle housing 18 is fixed to the middle portion of the trailing member 24 by the upper and lower seat members 20 and a pair of front and rear U bolts 22 near both ends in the vehicle width direction. ing. The trailing member 24 is usually made of a leaf spring material, and the eyeball portion 26 at the front end is pivotally supported by a bracket 32 via a shackle link 28 and a shackle pin 30. The brackets 32 are fixed to the left and right side rails 12 of the chassis frame 10 by rivets or bolts.

An air spring device 34 having an appropriate structure is arranged near the rear end of the trailing member 24.
As shown in the schematic configuration diagram of FIG. 2, the left and right air spring devices 34 are fixed to a lower seat member 36 fixed to the trailing member 24 and a bracket 38 fixed to the side rail 12. It is composed of an upper seat member 40 and rubber air bellows 42 having upper and lower ends fixed to the upper seat member 40 and the lower seat member 36.

The left and right air spring devices 34 are operated by a leveling valve 44, which is well known for its structure and operation. In the embodiment shown in FIG. 2, the leveling valve 44 is fixed to the rear axle housing 18 side, and the operating lever 46 of the leveling valve is connected to the chassis frame 10 side via a connecting rod 48. (In FIG. 2, the leveling valve 44 is illustrated adjacent to the left air spring device 34 for the convenience of the layout in the drawing. However, in reality, the center plane of the vehicle body in the front-rear direction is as close as possible to the layout. Is generally arranged in the vehicle width direction central portion, and the leveling valve 44 is fixed to the vehicle body frame 10 side, and the operating lever 46 of the leveling valve is connected via the connecting rod 48 to the rear axle housing. You may connect to the side.)

The operation mode of the leveling valve 44 is as follows.
Since it is well known in the art, it will be briefly described below. When the height of the chassis frame 10 with respect to the rear axle housing 18, that is, the rear shaft 16, becomes lower than the set height, the operating lever 46 is rotated clockwise in the drawing via the connecting rod 48, and the compressed air in the compressed air tank 50 is removed. As shown by the dotted line in the figure, the air bellows 42 are supplied into the air bellows 42 of the left and right air spring devices 34 and the air bellows extend upward, so that the chassis frame 10 is lifted up to the set height with respect to the rear shaft 16. To be On the contrary, when the height of the chassis frame 10 with respect to the rear shaft 16 becomes higher than the set height, the operating lever 46 is rotated counterclockwise in the figure via the connecting rod 48, and the compressed air in the air bellows 42 is moved to the leveling valve. It is discharged to the outside air from the exhaust port 52 of 44,
The air bellows 42 contracts and the height of the chassis frame 10 with respect to the rear shaft 16 is reduced to the set height.

Next, left and right hydraulically-actuated actuators 54, which are hydraulic cylinders, are interposed between the rear axle housing 18 near both ends in the vehicle width direction and the chassis frame 10 above the rear axle housing 18, respectively. In the illustrated embodiment, the cylinder 56 of the hydraulically-actuated actuator 54 is pivotally attached to the rear axle housing 18, and the piston shaft 60 of the piston 58 slidably fitted in the silling 56 is attached to the cross member 14 of the chassis frame 10. It is pivotally attached. The pressure chambers above and below the piston 58 are
8 are connected to each other by a small-diameter oil passage or orifice 62.

The left and right hydraulically-actuated actuators 54
Are controlled by the left and right control valves 64L and 64R, and the control valves 64L and 64R are
Is an appropriate shaking detection means for the vehicle body to detect roll displacement,
For example, a controller 6 that receives an output signal of the lateral acceleration sensor 66 and provides a drive output to each control valve.
8 operated. As an example, the controller 68 is provided with a changeover switch 70 that is manually operated by the driver of the tractor, and when the tractor is not pulling the trailer, the driver operates the changeover switch 70 to operate the changeover switch 70. Both the control valves 64L and 64R are set to the first switching position A, the neutral position B, and the second position.
The switching position C is fixed to the second switching position C, and the lower pressure chambers of the left and right hydraulically-actuated actuators 56 are configured to communicate with the oil tank 72, respectively. In place of the manually operated changeover switch 70, a means for automatically detecting that the tractor is not pulling the trailer, for example, a trailer coupling coupler 74 conceptually shown by a chain line in FIG. 1 is provided. The limit switch that outputs a signal when the coupler 74 is unloaded (when the trailer is not connected) automatically operates the controller 68,
The control valves 64L and 64R may be fixed to the second switching position C, respectively.

In FIG. 2, reference numeral 76 is an oil pump as a pressure oil source, 78 is a relief valve interposed between a discharge side oil passage 80 and a return side oil passage 82 of the oil pump 76, and 84 is the above-mentioned. An accumulator connected to the discharge side oil passage 80, and 86 is an accumulator or a gas spring connected to the lower pressure chambers of the left and right hydraulically-actuated actuators 54 via an orifice or a throttle valve 88, and enters from the road surface as described above. It attenuates the vibration in the relatively high unsprung resonance frequency range.

The operation mode of the hydraulic active suspension device including the left and right hydraulically-actuated actuators 54 is well known in the art and will be briefly described below. In addition, the tractor is traveling straight ahead and the lateral acceleration sensor 66
Outputs a signal indicating that the lateral acceleration generated in the tractor is substantially zero, the controller 68 holds both the left and right control valves 64L and 64R in the neutral position B. At this time, when the chassis frame 10 is vertically displaced relative to the rear axle housing 18, the working pressure oil in each actuator 54 flows between the upper and lower pressure chambers through the orifice of the piston 58 or the oil passage hole 62, The actuator 54 acts as a kind of shock absorber that produces damping efficiency due to throttling loss of the operating pressure oil flowing through the orifice or oil passage hole 62.

Next, when the tractor turns to the right, for example,
The left control valve 64L is switched to the first switching position A by the output signal of the lateral acceleration sensor 66, and the pressure oil discharged from the oil pump 76 is supplied to the lower pressure chamber of the left pressure-responsive actuator 54. An upward force acts on the piston 58 and the piston shaft 60 due to the difference in pressure receiving area between the upper pressure chamber and the lower pressure chamber of the piston 58.
At the same time, since the right control valve 64R is switched to the second switching position C by the output signal of the lateral acceleration sensor 66, the right hydraulically actuated actuator 54
The lower pressure chamber of is communicated with the oil tank 72. As a result, the roll displacement during the right turn of the tractor is positively suppressed by the difference in the lifting force of the left and right hydraulically-actuated actuators 54, and the roll displacement is positively suppressed in the same manner during the left turn. Is performed.

As described above, the air spring device 34 and the hydraulic active suspension device including the hydraulically-actuated actuator 54 are provided side by side on the rear shaft 16 of the tractor to keep the vehicle height constant and to provide the anti-roll effect. To improve the ride quality. By the way, in this type of tractor, the acting load of the rear shaft 16 changes greatly when a trailer carrying a cargo of a predetermined weight is towed, that is, when the trailer is connected and when the trailer is not towed. Corresponding to a small load acting on the rear shaft 16 in a single vehicle, even if the pressure of the working pressure oil of the hydraulically responsive actuator 54 is set to the minimum pressure of the accumulator or the gas spring 86, a sufficient anti-roll effect is produced when the trailer is connected. The hydraulic pressure generated load of the above-mentioned actuator 54, which is designed for
Conventionally, there is a fear that the rubber bellows 42 of the air spring device 34 may be fully extended and damaged or the durability may be impaired. Further, since the air spring device 34 is extended, the posture of the entire tractor is in a forward leaning nose dive state. It gives the person an uncomfortable feeling of discomfort.

However, according to the configuration of the present invention, the left and right control valves 64L and 64R are respectively moved to the second switching position C by means of switching the changeover switch 70 in the case of a single vehicle or detecting the trailer non-connection state instead. Since the left and right hydraulically-actuated actuators 54 are connected to the oil tank 72 and become substantially atmospheric pressure, the air spring device 34 is not subjected to an excessive hydraulic pressure, and the air bellows 42 is not damaged. It is reliably prevented and the durability is improved. Furthermore, since the air spring device 34 is not extended by hydraulic pressure, the posture of the entire tractor does not lean forward,
There is an advantage that the driver does not feel discomfort or anxiety. Further, when the hydraulically-actuated actuator 54 acts on the extension side in this state, the oil tank 72 is sucked into the actuator 54, so it is clear that the damping function can be exerted as a shock absorber by the line resistance. is there. In the case of a tractor, most of the load of the trailer acts on the rear shaft. Therefore, the air spring device 34 and the hydraulically-actuated actuator 54 are usually provided only on the rear shaft, and it is sufficient. If desired, a similar configuration can be adopted for the front shaft.

[0021]

As described above, the suspension system for a tractor according to the present invention is a hydraulic system in which the rear shaft of the tractor has an air spring device for controlling the vehicle height and a hydraulically responsive actuator that suppresses the shaking of the vehicle body. In a vehicle supported by an undercarriage frame via an active suspension device, when the tractor is not pulling a trailer, the hydraulically-actuated actuator is constantly connected to an oil tank via a control valve that controls its operation. It is characterized by being communicated, and prevents an excessive load in the extension direction of the air spring device during running of a single vehicle which occurs when an air spring device and a hydraulic active suspension device are installed side by side on a tractor, especially a rear shaft thereof. Prevents damage, improves durability, and protects the entire tractor from unnatural There is the advantage that it is possible to prevent that the Mino attitude.

[Brief description of drawings]

FIG. 1 is a side view of an essential part showing an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of the apparatus shown in FIG.

[Explanation of symbols]

10 ... Chassis frame, 12 ... Side rail, 14 ... Cross member, 16 ... Rear shaft, 18 ... Rear axle housing, 34 ... Air spring device, 54 ... Hydraulically actuated actuator.

Claims (1)

[Claims] 1. A rear shaft of a tractor is supported by a chassis frame via an air spring device for controlling a vehicle height and a hydraulic active suspension device having a hydraulically responsive actuator that suppresses vibration of a vehicle body. A tractor suspension device, wherein the hydraulically-actuated actuator is continuously communicated with an oil tank via a control valve that controls the operation of the single vehicle when the tractor is not pulling a trailer.