JPH05201221A - Suspension control device for self-propelled work vehicle - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a suspension control device for a self-propelled work vehicle that prevents the body from leaning when the steering wheel is turned suddenly during high-speed traveling. [Structure] A suspension mechanism which is provided between an axle and a vehicle body, and which includes cushioning members 4L and 4R for absorbing vibration of the axle and suspension cylinders 3L, 3R, 6L and 6R, and the suspension cylinders 3L, 3R and 6
In a suspension control device for a self-propelled work vehicle including lock means 11L and 11R for locking L and 6R, a vehicle speed detecting means 17 for detecting a vehicle traveling speed, and an operation amount detecting means 25L for detecting a steering operation amount, 25
R, vehicle speed detecting means 17 and operation amount detecting means 25L,
Lock means 11L, 11R based on the detection output of 25R
Control means 16, 14L, 14 for controlling the operation / non-operation of the
And R.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suspension control device used in a self-propelled work vehicle such as a wheel hydraulic excavator.

[0002]

2. Description of the Related Art In this type of wheel hydraulic excavator, a suspension mechanism is provided between an axle and a vehicle body. This suspension mechanism is composed of a cushioning member such as a spring and a suspension cylinder that expands and contracts according to the vibration of the axle, and absorbs the vibration of the axle by the cushioning member.
It is designed to improve riding comfort when the vehicle is running. Further, during work such as excavation, the suspension cylinder is locked by a lock mechanism to prohibit the operation of the cushioning member to prevent the vehicle from tilting and improve the stability.

[0003]

However, if the suspension cylinder is kept in an operating state (unlocked state) when the vehicle is traveling, for example, when the so-called sudden steering wheel is turned during high-speed traveling, the vehicle body moves in the steering direction due to centrifugal force. There is a problem that the stability is impaired due to a large inclination in the opposite direction.

An object of the present invention is to provide a suspension control device for a self-propelled work vehicle which prevents the body from leaning when the steering wheel is suddenly turned during high-speed traveling.

[0005]

1 and 2 showing an embodiment, the present invention is provided between an axle 2 and a vehicle body 5 to absorb vibration of the axle 2. A suspension mechanism composed of cushioning members 4L, 4R and suspension cylinders 3L, 3R, 6L, 6R that expand and contract according to vibrations of the axle 2, and locking means 11 for locking the suspension cylinders 3L, 3R, 6L, 6R.
It is applied to a suspension control device for a self-propelled work vehicle equipped with L and 11R. Then, the vehicle speed detecting means 17 for detecting the vehicle traveling speed, the operation amount detecting means 25L, 25R for detecting the steering operation amount, and the lock means 11L based on the detection outputs of the vehicle speed detecting means 17 and the operation amount detecting means 25L, 25R. , 11R for controlling the operation / non-operation of the control means 16, 14L, 14R, thereby solving the above problems. In particular, the invention of claim 2 is one in which the control means 16, 14L, 14R are configured as follows. That is, the control means 16, 14L, 14R
Activates the locking means 11L, 11R at least when the detected vehicle traveling speed is equal to or higher than the predetermined speed and the steering operation amount is equal to or higher than the predetermined amount.

[0006]

Operation: Vehicle speed detecting means 17 and operation amount detecting means 25
Based on the detection outputs of L and 25R, that is, the vehicle traveling speed and the steering operation amount, the lock means 11L and 11R are activated / deactivated (steering cylinders 3L, 3R, 6).
Whether or not L and 6R are locked is controlled. In particular, when the vehicle traveling speed is equal to or higher than a predetermined speed and the steering operation amount is equal to or more than a predetermined amount, the locking means 11L and 11R are operated to lock the suspension cylinder.
The cushioning members 4L and 4R do not work and the vehicle body does not tilt even when the steering wheel is suddenly turned during high speed traveling.

Incidentally, in the section of means and action for solving the above problems for explaining the constitution of the present invention, the drawings of the embodiments are used for the purpose of making the present invention easy to understand. It is not limited to.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a wheel type hydraulic excavator will be described with reference to FIGS. FIG. 2 is a schematic view of the main part of the wheel hydraulic excavator as seen from the front of the vehicle. A chassis frame 5 is mounted on the front axle 2 connecting the left and right front wheels 1L, 1R via a pair of buffer springs 4L, 4R and a pair of suspension cylinders 3L, 3R. Although not shown in FIG. 2, a pair of buffer springs 4 is similarly provided between the rear axle connecting the left and right rear wheels and the chassis frame 5.
L and 4R and a pair of suspension cylinders (indicated by 6L and 6R in FIG. 1) are provided. Buffer spring 4L,
4R supports the vehicle body and absorbs road surface loads input from the tires 1L and 1R.

FIG. 1 is a diagram showing a suspension control device according to the present invention. As shown in the figure, each of the cylinder chambers of the suspension cylinders 3L, 3R, 6L, 6R described above has lock valves 11L, 11R, which are check valves.
It is possible to communicate with the tank 12 via. The lock valve 11L on the left side maintains a closed state (operating state) when the pressure in the pilot line 13L is less than a predetermined value, and at this time, the cylinder chambers of the suspension cylinders 3L and 6L are blocked and the suspension cylinders 3L and 6L are Locked. When the pressure in the pilot conduit 13L becomes equal to or higher than a predetermined value, the lock valve 11L opens (becomes inactive), and at this time, the suspension cylinders 3L, 6L.
Each cylinder chamber of L communicates with the tank 12, and the suspension cylinders 3L and 6L are unlocked. Similarly, the lock valve 11R on the right side similarly has the pilot conduit 13
The suspension cylinders 3R and 6R are locked and released depending on whether the pressure of R is less than a predetermined value.

Here, the pilot lines 13L and 13
R is connected to the pilot pump 15 via solenoid valves 14L and 14R, respectively. Solenoid valves 14L, 14R
Can be switched between an A position for communicating the pilot conduits 13L and 13R with the tank 12 and a B position for guiding the discharge oil of the pilot pump 15 to the pilot conduit 13, and the switching is performed by a signal from the controller 16. ..

On the other hand, the oil discharged from the steering pump indicated by reference numeral 21 is guided to the steering cylinder 23 through the steering valve 22, and the steering cylinder 23 is driven to perform steering. Reference numeral 24 denotes a steering wheel for operating the steering valve 22, and the steering amount of the vehicle depends on the operation amount (steering operation amount) of the steering valve 22 by the steering wheel 24. Reference numerals 25L and 25R are pressure switches that are turned on / off according to the pressure in the pipe lines 26L and 26R between the steering cylinder 23 and the steering valve 22.

Here, the pressure in the pipelines 26L and 26R increases as the amount of steering valve 22 operation in the left-right direction increases, and the pressure switches 25L and 25R respectively.
The R is turned off when the pressure in the pipelines 26L and 26R is less than a predetermined value, and is turned on when the pressure exceeds a predetermined value. That is, the pressure switch 25L is switched from OFF to ON when the left operation amount of the steering valve 22 is equal to or more than a predetermined amount, and the pressure switch 25R is when the right operation amount of the steering valve 22 is equal to or more than the predetermined amount. It will be switched from off to on. These pressure switches 25L, 2
The 5R on / off signal is input to the controller 16. Further, the vehicle traveling speed (hereinafter, referred to as vehicle speed) detected by the vehicle speed sensor 17 is also input to the controller 16.

Next, the control procedure of the controller 16 will be described with reference to the flowchart of FIG. In step S1, the pressure switches 25L and 25R are turned on.
The off state and the vehicle speed V which is the detection result of the vehicle speed sensor 17 are read. If it is determined in step S2 that the vehicle speed V is less than the preset predetermined speed V ₀ , in step S3 the solenoid valve 14
Both L and 14R are switched to the B position. As a result, the oil discharged from the pilot pump 15 is transferred to the solenoid valves 14L and 14R.
Through the pilot pipes 13L and 13R, the lock valves 11L and 11R are opened, and the suspension cylinders 3L, 3R, 6L, and 6R are unlocked (extendable and contractable). Therefore, the vibrations of the front axle 2 and the rear axle (not shown) are dampened by the buffer spring 4.
It is absorbed by L and 4R, and riding comfort can be improved.

On the other hand, in step S2, the vehicle speed V is the predetermined speed V.
If it is determined to be ₀ or more, the process proceeds to step S4, and it is determined whether the pressure switches 25L and 25R are on or off. If both the pressure switches 25L and 25R are determined to be off, the process proceeds to step S3, and if either of them is determined to be on, the process proceeds to step S5. Pressure switch 25 in step S5
When L is determined to be on, the solenoid valve 14R is switched to the A position. As a result, the oil discharged from the pilot pump 15 is not guided to the pilot pipe line 13R, the lock valve 11R is closed, and the suspension cylinders 3R and 6R are locked (non-expandable state). At this time, the solenoid valve 14L remains in the B position, and therefore the suspension cylinders 3L and 6L maintain the unlocked state.

When it is determined in step S5 that the pressure switch 25R is on, the solenoid valve 14L is switched to the A position.
As a result, the oil discharged from the pilot pump 15 is not guided to the pilot line 13L, and the lock valve 11
L is closed, and the suspension cylinders 3L and 6L are locked. At this time, the solenoid valve 14R remains in the B position, and therefore the suspension cylinders 3R, 6R
R holds the unlocked state.

According to the above procedure, when the vehicle traveling speed V is equal to or higher than the predetermined speed V ₀ and the steering operation amount is equal to or more than the predetermined amount, the suspension cylinders 3L, 6L or 3R, 6R opposite to the steering operation direction are operated. Locked. This prevents the vehicle body from leaning in the opposite direction to the steering direction even when the steering wheel is suddenly turned during high-speed traveling. During the work, in response to a switch operation (not shown), the suspension cylinders 3L, 3R, 6L,
6R should be locked together. According to this, the inclination of the vehicle during work can be prevented and the stability can be improved.

In the configuration of the above embodiment, the axle 2
Is the axle, the buffer springs 4L and 4R are the buffer members, the lock valves 11L and 11R are the locking means, the vehicle speed sensor 17 is the vehicle speed detecting means, the pressure switches 25L and 25R are the operation amount detecting means, and the controller 16 and the solenoid valve. 14L, 1
Each of the 4Rs constitutes a control means.

In the above description, the one provided with the front and rear suspension cylinders has been described, but the one provided with only one of the front and rear may be used. Further, the configuration of the suspension mechanism is not limited to the embodiment, and for example, an accumulator may be used instead of the buffer spring. Further, the mechanism for locking the suspension cylinder is not limited to the embodiment. Furthermore, although the description has been given for the wheel type hydraulic excavator, the present invention can be applied to other self-propelled work vehicles.
Instead of the pressure switches 25L and 25R, the stroke of the steering cylinder may be detected to detect the steering operation amount.

[0019]

According to the present invention, the locking / unlocking of the suspension cylinder is controlled on the basis of the vehicle traveling speed and the steering operation amount. Therefore, at least the vehicle traveling speed is equal to or higher than a predetermined speed and the steering operation amount. If the suspension cylinder is locked when is greater than or equal to a predetermined amount, it is possible to prevent the leaning of the vehicle body when the steering wheel is suddenly turned during high-speed traveling and to ensure stability.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a suspension control device for a self-propelled work vehicle according to the present invention.

FIG. 2 is a schematic view of the suspension mechanism of the wheel hydraulic excavator as seen from the front of the vehicle.

FIG. 3 is a flowchart showing a processing procedure of a controller.

[Explanation of symbols]

 1L, 1R Front wheel 2 Front axle 3L, 3R, 6L, 6R Suspension cylinder 4L, 4R Buffer spring 5 Chassis frame 11L, 11R Lock valve 14L, 14R Solenoid valve 15 Pilot pump 16 Controller 17 Vehicle speed sensor 21 Steering pump 22 Steering valve 23 Steering Cylinder 24 Steering wheel 25L, 25R Pressure sensor

Claims (2)

[Claims] 1. A suspension mechanism which is provided between an axle and a vehicle body, and which includes a suspension member that absorbs vibration of the axle and a suspension cylinder that expands and contracts in response to the vibration of the axle, and a locking unit that locks the suspension cylinder. In a suspension control device for a self-propelled work vehicle including: a vehicle speed detecting means for detecting a vehicle traveling speed; an operation amount detecting means for detecting a steering operation amount; and a detection output of the vehicle speed detecting means and the operation amount detecting means. And a control means for controlling the operation / non-operation of the locking means based on the above. 2. The control means activates the locking means at least when the detected vehicle traveling speed is equal to or higher than a predetermined speed and the steering operation amount is equal to or higher than a predetermined amount. Suspension control device for the self-propelled work vehicle described.