JPS62275812A - Wheel shaft suspension for wheel type construction vehicle - Google Patents

Abstract

PURPOSE:To improve the extent of groundability in a tire, by installing two types of pistons in a suspension cylinder, while moving the piston on one side with operation of a selector valve and thereby adjusting a stroke rate of the piston on the other, and changing the maximum rockable angle of a wheel shaft. CONSTITUTION:In case of running on the ground having large uneven undulations, the maximum rockable angle of a wheel shaft 6 is changed into extension. That is to say, a selector switch 22 is operated to a (a) position and a shutoff valve 17 is selected to a (c) position. And, a selector valve 31 is operated to a (f) position, and oil in each second piston oil chamber 30 of symmetrical culinders 12 is opened to an oil tank 21 through respective oil passages 38, 39 and 40, thus each second piston 28 is made into freedom. At this time, since the wheel shaft 6 is rocked centering on a center pin 11 of an equalizer 9, a clearance between the top of a first piston 27 and the underside of a stepped part 26 in a cylinder tube comes to 2X(S1+S2), so that the maxi mum rockable angle is thus expanded.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention Field of Industrial Application The present invention relates to a suspension system for a wheel axle for a wheeled construction vehicle.

BACKGROUND OF THE INVENTION FIG. 5 is an overall side view of a wheeled construction vehicle running on a ground having large unevenness. In the vehicle, reference numeral 1 indicates an upper rotating body and 2 indicates a lower traveling body. Figure 6 is a view of the white lower traveling body 2 in Figure 5 seen from A, where 3'' is the lower traveling frame, 6 is the wheel axle, 8 is the tire, 9 is the equalizer, and 12'' is the suspension cylinder. In the figure, the girder hole 4 of the lower traveling frame 3'' and the center hole 10 of the equalizer 9 fixed to the wheel axle 6 are pivotally supported by a center pin 11.

On the other hand, brackets 5 are provided on both left and right sides of the girder part of the lower traveling frame 3', and brackets 7 are provided on both left and right sides of the wheel axle 6, and a pair of suspension cylinders 12' are provided between the brackets 5 and 7, respectively. It is pivotally connected by bins 13 and 14 in a telescopic manner.

FIG. 7 is a block diagram of a suspension system around a wheel shaft equipped with a suspension cylinder according to the prior art.
1.12" is the left and right suspension cylinder, 151..151 is the piston, 16L, 16
++ denotes a piston oil chamber, 17 denotes a hydraulic shaft off valve having a pneumatic pressure receiver 18, 19L, 19E denotes left and right oil passages connecting the left and right suspension cylinders 12″L, 12′l and the shaft off valve 17. , 20 is an oil passage that communicates with the oil tank 21 from the shutoff valve 17, 22 is a pneumatic changeover switch, and 23 is a changeover switch 2.
2 and the pneumatic pressure receiver 18, 24 is an air tank, and 25° is a swing joint for hydraulic and pneumatic circuits provided at the construction vehicle swing joint.

The wheel shaft suspension system of the prior art is composed of the above-mentioned equipment parts, and the operating functions thereof will be described next. When the wheel axle 6 is at a horizontal level, the left and right suspension cylinders are 12°.

12" stroke I in the direction of cylinder reduction as shown in the figure
It has s +. Therefore, when the construction vehicle travels on uneven ground, the changeover switch 22 is set to the I position, so the shutoff valve 17 is located at the C position. Left and right suspension cylinders 12°L, 12°8 piston oil chambers 16L, 16E, shaft off valve 17
The wheel shafts 6 are able to swing until the stroke amount Sl of either the left or right suspension cylinder becomes s, -0 because they are in communication via the constricted portion in the first section. For example, the dimension of Sl in the piston oil chamber 16i is O.
Then, the dimensions in the piston oil chamber 16L are 2 x 31
becomes. If the swing angle in this case is 01, the wheel axle 6 can swing about the center pin 11 within a range of +01 and -01 with respect to the horizontal level. Note that the shaft off valve 17 is connected to an oil tank 21 through an oil passage 20.
The left and right suspension cylinders 1
Hydraulic oil is constantly replenished against the negative pressure in the piston oil chambers 16L and 16. In the grounded state, switch the selector switch 22 to the open position.The air pressure in the air tank 24 acts on the air pressure receiver 18 through the air pipe 23, and switches the shaft off valve 17 to the 2nd position. The oil in the piston chambers 16L and 16m is closed by the check valve, and the lower traveling frame 3'' and the wheel axle 6 are hydraulically locked.

Problems to be Solved by the Invention In the wheel-type construction vehicle of the prior art, either the front or rear wheel axle is fixed to the lower traveling frame as a wheel axle suspension system, and the other wheel axle is movable for 13 hours. The tire's ground contact was addressed. But in this case,
There is a limit to the maximum swing angle θ of the wheel axle due to structural limitations of the construction vehicle or the overturning angle in the left and right directions. For this reason, when a wheeled construction vehicle of the prior art travels on a ground with large unevenness, the condition of the unevenness of the ground exceeds the wheel axle layer large swing angle θ, and the lower traveling body is 1 of the tires installed in 4 locations
In some places, the tires were raised above the ground, causing the tires to spin or slip, making it difficult or impossible to drive. Therefore, the present invention aims to increase the maximum swing angle θ of the wheel axle of the conventional wheeled construction vehicle and improve the ground contact performance of the tires.

Means for Solving the Problems The means of the present invention taken to solve the above problems are as follows: (a) A first piston and a second piston are installed in the suspension cylinders installed between the left and right brackets of the lower traveling frame girder and the wheel axle, respectively. A piston is provided, and the second piston is moved by introducing pressure oil into the oil chamber for the second piston or by opening the oil chamber to the tank communication passage by switching the port and the switching valve. The stroke amount of the first piston is adjusted by movement, and the maximum rocking angle of the wheel axle can be changed.

Operation A. A 1 m long suspension cylinder is provided with a first piston on the lower side and a second piston on the upper side, using the internal stepped part of the cylinder tube as a stopper.
The upper side of the second piston serves as a first piston oil chamber and a second piston oil chamber. Therefore, when pressure oil is being introduced into the second piston oil chamber above the second piston, the second piston is lowered to the stepped portion. Therefore, the dimension between the stepped lower surface and the lower end of the second piston is three, and the first piston oil chamber has a dimension of 31 between the lower end of the second piston and the upper surface of the first piston. There is a movable amount. Therefore, the wheel axle in this case has a maximum swingable angle of +θ to -θ1 with respect to the horizontal level.

(b) When the pressure oil in the second piston oil chamber is released to the tank communication passage, the second piston becomes free because no hydraulic pressure is applied to it from either the upper surface side or the lower surface side.

C. As mentioned above (when the second piston is in a free state, the maximum movable amount of the first piston is Sl + St. Therefore, the wheel axle is +(θ,
+θt) to −(θ1+08), which is the maximum swing angle, which is expanded compared to the above-mentioned term A.

Example Hereinafter, the present invention will be described in detail based on embodiments.

FIG. 1 is a configuration diagram of the suspension system of the present invention. In the figure, 3 is a lower running frame of a construction vehicle, 6 is a wheel axle, 9 is an equalizer fixed to the wheel axle 6, and 11 is a girder part of the lower running frame 3. A center pin, 12, . 12. are a pair of left and right suspension cylinders that connect the left and right brackets of the girder portion of the lower traveling frame 3 and the left and right brackets of the equalizer 9. The structures of the suspension cylinders 12L and 12* are the same, but there is a stepped part 2 inside the cylinder tube.
6L and 26K, with a first piston 2 on the bottom of each.
7L and 27, and above them there is a second piston 28L,
281 is incorporated. Therefore, there are first piston oil chambers 29L, 29E and second piston oil chambers 30L, 30m as oil chambers on the upper side of each piston. Also, 31
is a switching valve, 32 is a hydraulic pump, 33 is a relief valve, 34
L, 34m, 35.36, 37.3B, 39°40 are oil passages, and 25 is a swing joint for hydraulic and pneumatic circuits. Note that FIG. 2 is a detailed cross-sectional view of the left suspension cylinder 12L in FIG. 1.

Next, the operational functions of the suspension system of the present invention will be described. 1st
In the figure, when the pneumatic changeover switch 22 is operated to the A position 1, the shaft off valve 17 is switched to the C position. At that time, the left and right suspension cylinders (hereinafter simply referred to as cylinders) 12t, 12* first piston chamber 2
9L and 29 are opened to the oil tank 21 through oil passages 34L and 341, a constricted portion in the C position section of the shaft off valve 17, and an oil passage 35. Then, when the switching valve 31 is operated to the water level 1, the pressure oil discharged from the hydraulic pump 32 passes through the oil passage 36, the H position of the switching valve 31, the oil passage 37, the oil passages 38 and 39, and the second piston oil chamber 30L. 30. will be introduced in For this reason, the lower surfaces of the shoulders of the second pistons 28L, 281 are arranged in the cylinder tube inner stepped portions 26L, 26. At the same time, the downwardly protruding lower ends of the second pistons 28L and 28m protrude downward by a length of 32 from the lower surfaces of the stepped portions 26L and 26R. Therefore, when the switching valve 31 is operated to the water position and the wheel axle 6 is at a horizontal level, there is a gap between the upper surfaces of the first pistons 27L and 271 and the downwardly projecting lower ends of the second pistons 28L-28N as shown in FIG. There exists an interval <, SI.

Figure 3 shows a construction vehicle's changeover switch 22 and changeover valve 3.
In Figure 0, which is a rear front view of the lower traveling body traveling on uneven ground with 1 in the same operating position as in Figure 1, the right tire 8 of the wheel axle 6 is in contact with a convex part of the ground. At the same time, the first piston 27 in the right cylinder 12. The upper surface of the second piston 28. It is in contact with the downwardly protruding lower end of.

When , the wheel shaft 6 swings about the center pin 11 of the equalizer 9, so the first piston oil chamber 29. The oil inside goes through the oil passage 34E, the throttle part in the C position section of the shut-off valve 17, and the oil passage 34L to the left cylinder 12L.
The oil is sent into the first piston oil chamber 29L. Therefore, the distance between the upper surface of the first piston 27L in the left cylinder 12L and the downwardly protruding lower end of the second piston 28L is (2xs+). At this time, since the angle of inclination of the wheel axle 6 with respect to the horizontal level is 01, the maximum swingable angle of the wheel axle 6 in FIG. 3 is 101 to -θ1.

However, when driving on a ground with large unevenness that cannot be handled by the above-mentioned maximum swing angle angles 101 to -0, the maximum swing angle of the wheel axle 6 is enlarged. The switch 22 is operated to the A position, and the shutoff valve 17 is switched to the C position. Then, when the switching valve 31 is operated to the position, the left and right cylinders 12
L and 12. The oil in the second piston oil chamber 3oL and 30m, respectively, is in the oil passage 38, 39, oil passage 37, and switching valve 3.
1, it is opened to the oil tank 21 via the oil passage 40. For this purpose, the second piston 28. and 28. are in a free state within 30 m of the left and right second piston oil chambers 3OL, respectively. Therefore, as shown in FIG. 4, when the right tire 8 of the wheel axle 6 is in contact with the convex part of the ground, the upper surface of the right cylinder 12 and the inner cylinder 1 piston 27 is connected to the stepped part 26 of the cylinder tube. It is in contact with the bottom side of. In this case as well, the wheel axle 6 moves around the center pin 11 of the equalizer 9, so the left cylinder 12°, the inner cylinder 1, the piston 2
The distance between the upper surface of the cylinder tube 7L and the lower surface of the cylinder tube inner stepped portion 26L is 2X (SI+S).At that time, the inclination angle of the wheel axle 6 with respect to the horizontal level is θ□, but the third
Since the inclination angle θ1 in the figure becomes 0>θ1, the maximum swingable angle is expanded to +θ2 to −02.

Effects of the Invention As described above, in the wheel axle suspension system of the present invention, the first piston and the first piston are installed in the suspension cylinder installed between the left and right brackets of the lower traveling frame bent portion and the left and right equalizer brackets of the wheeled construction vehicle. 2 pistons were provided. By switching the switching valve installed near the driver's seat, pressure oil can be introduced into the second piston oil chamber above the second piston to move the second piston downward, or the second piston oil can be moved downward. The chamber is opened to the oil tank and the second piston is placed in a free state. Therefore, when hydraulic pressure is applied to the second piston, the maximum possible stroke amount of the first piston relative to wheel axle rocking is set to (2xs+), and when the second piston oil chamber is opened to the tank communication passage, the maximum possible stroke amount is set to (2xs+). 2 x (
sI+sz).

In the prior art, each of the left and right suspension cylinders has only one piston, so the maximum possible stroke amount for wheel axle rocking is set to (2×31). In other words, the maximum swing angle θ1 of the wheel axle is limited to correspond to general roads and relatively flat uneven ground due to reasons such as the horizontal overturning angle of the wheeled construction vehicle. For this reason, when the unevenness of the ground is at its maximum [
When the 8-moveable angle θ1 is exceeded, one of the four tires attached to the front, rear, left, and right of the lower traveling body spins or slips, causing trouble in which running becomes difficult or impossible.

However, in the wheel axle suspension system of the present invention, when a wheeled construction vehicle travels at high speed on relatively flat ground with little unevenness, the second piston is moved downward by operating the switching valve, and the left and right suspension cylinders are moved downward. The maximum stroke amount of the telescopic operation was set to (2×S,), and the maximum swingable angle of the wheel axle was set to 101 to -01. When the wheeled construction vehicle travels on even more uneven ground, the driver switches the switching valve to set the maximum stroke amount of the left and right suspension cylinders to 2x (s).

+SZ), and the maximum tg movement angle of the wheel axle is 102
It can be expanded to -82. Therefore, when driving on highly uneven ground, the ground contact of the tires at four locations on the front, rear, left and right sides has been significantly improved, reducing problems such as difficulty in driving or being unable to drive. Also,
The driver operates the switching valve according to the driving ground conditions.
Since the maximum swing angle of the wheel axle can be changed, stability during driving can be maintained optimally.

[Brief explanation of the drawing]

FIG. 1 is a front view of a wheel axle suspension system of the present invention having hydraulic and pneumatic circuits, FIG. 2 is a detailed sectional view of a suspension cylinder, and FIGS. 3 and 4 are front views of the wheel axle suspension system of the present invention. , Figure 5 is an overall side view of the wheeled construction vehicle.
FIG. 6 is a view of the white undercarriage shown in FIG. 5 viewed from the 8th direction, and FIG. 7 is a front view of a conventional wheel axle suspension system. 3.3°・・・・・・・・・Lower traveling frame 6・
・・・・・・・・・・・・・・・Wheel axle 9・・・・・・・
・・・・・・Equalizer 12, . 12°...Left suspension cylinder 12E, 12°8...Right suspension cylinder 17...Shaft off valve 22... ...Selector switch 27L, 271...First piston 28L, 281...Second piston 29L, 291...First piston oil chamber 30L, 30m
...Second piston oil chamber 31...
・More than switching valve

Claims (1)

[Claims] The girder hole of the lower running frame for wheeled construction vehicles and the center hole of the equalizer fixed to the wheel axle are pivoted by a center pin, and a pair of suspension cylinders is extended and retracted between the left and right brackets of the girder and wheel axle, respectively. In the lower traveling body, which is freely mounted and is connected to the wheel shaft so as to be swingable about the center pin, a first piston and a second piston are provided in the suspension cylinder, and pressure is applied to the oil chamber of the second piston by switching the switching valve. The second piston is moved by introducing oil or opening the oil chamber to the tank communication passage, and by moving the second piston, the stroke amount of the first piston can be adjusted, and the maximum swing angle of the wheel axle can be changed. A wheel axle suspension system for a wheel-type construction vehicle, characterized by comprising: