JPH0667683B2 - Wheel axle suspension for wheeled construction vehicles - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wheel shaft suspension system for a wheel-type construction vehicle.

2. Description of the Related Art FIG. 5 is an overall side view of a wheel-type hydraulic backhoe, which is one of wheel-type construction vehicles, traveling on a ground with a lot of undulations, and 1 is an upper swing body and 2 is a lower traveling body. FIG. 6 is a view of the front shaft of the lower traveling body 2 shown in FIG.
3'is a lower traveling frame, 6 is a wheel shaft, 8 is a tire, 9
Is an equalizer and 12 'is a suspension cylinder.
In the figure, the girder center hole 4 of the lower traveling frame 3'and the center hole 10 of the equalizer 9 fixed to the wheel shaft 6 are pivotally supported by a center pin 11. On the other hand, brackets 5 and wheel shafts 6 are provided on the left and right sides of the girder portion of the lower traveling frame 3 '.
Brackets 7 are provided on both the left and right sides of the
1 pair of suspension cylinders between 7 and 7 each
2'is pivoted by pins 13 and 14.

The prior art suspension cylinder in the wheel suspension system having the above-described structure has the structure shown in FIG. 7 and a hydraulic circuit. That is, 12 ' _L and 12' _R are left and right suspension cylinders, 15 _L and 15 _R are pistons, 16 _L and 16 _R are piston oil chambers, and 17 is a hydraulic shutoff valve having a pneumatic pressure receiving portion 18. , 19 _L , 19
_R is the oil chamber 1 of the left and right suspension cylinders 12 ' _L , 12' _R
Left and right oil passages that connect the 6 _L and 16 _R and the shutoff valve 17, 20 is an oil passage that connects the shutoff valve 17 and the oil tank 21, 22 is a pneumatic changeover switch, and 23 is a changeover switch 22 and pneumatic pressure. Air piping connecting to the pressure receiving part 18, 24 is an air tank,
25 'is provided between the upper revolving structure 1 and the lower traveling structure 2,
It is a swing joint that connects hydraulic and pneumatic circuits.

The wheel axle suspension system of the prior art is constituted by the above-mentioned equipment parts, and its operation function will be described below. When Tanwajiku 6 is in a horizontal level, the left and right suspension cylinders 12 _'L, 12' _R has a stroke amount S ₁ of allowable cylinder reduction direction as shown in FIG. Therefore, when the construction vehicle travels on the undulating ground, when the selector switch 22 is set to the a position and the pneumatic pressure receiving portion 18 is opened to the atmosphere through the air pipe 23, the shutoff valve 17 is in the c position. At this position, the piston oil chambers 16 _L and 16 _R of the left and right suspension cylinders 12 ′ _L and 12 ′ _R communicate with each other via the throttle section in the C position section of the shutoff valve 17, so that the wheel shaft 6 is It becomes possible to swing within the range of the stroke amount S ₁ of either the left or right suspension cylinder. For example, if the swing angle when the dimension of the stroke amount S ₁ on the piston oil chamber 16 _R side becomes 0 is + θ ₁ , the wheel shaft 6 is centered on the center pin 11 and + θ ₁ and −θ with respect to the horizontal level. _It can swing within the range of ₁ . Since the shut-off valve 17 communicates with the oil tank 21 through the oil passage 20, the piston oil chambers 16 _L and 16 _{R of} the left and right suspension cylinders 12 ′ _L and 12 ′ _R become negative pressure for some reason. Also, the hydraulic oil is replenished at any time. When the hydraulic backhoe stops traveling and starts work, the air pressure in the air tank 24 is changed to the air pressure via the air pipe 23 by switching the changeover switch 22 to the low position while the left and right tires 8 are in contact with the ground. It acts on the pressure receiving portion 18, and the shutoff valve 17 is switched to the two position. As a result, the check valve in the two-position section shuts off the oil flow between the piston chambers 16 _L and 16 _R ,
The lower traveling frame 3'and the wheel shaft 6 are hydraulically locked.

In the wheel type construction vehicle such as the wheel type hydraulic backhoe of the prior art, as a wheel shaft suspension system, either the front wheel shaft or the rear wheel shaft is fixed to the lower traveling frame, and the other wheel shaft is fixed. It was possible to swing the tire to deal with the ground contact of the tire when traveling on rough terrain. However, due to the structure of various wheel-type construction vehicles, the center of gravity tends to be high, and
Since many machines are self-propelled, the maximum swing angle θ of the wheel shaft is limited to the above safe range in order to maintain sufficient safety against lateral overturning even when changing direction at high speed. It was Therefore, when the wheel-type construction vehicle of the related art moves at low speed on the ground with large undulations, the undulation state of the ground exceeds the maximum swingable angle θ of the wheel shaft,
Inside the tires that are attached to the front, rear, left and right of the undercarriage 1
In two or two places, the tire floated off the ground, causing the tire to slip or slip, making it difficult to run or unable to escape. Therefore, an object of the present invention is to improve escapeability from rough terrain by increasing the maximum wheel shaft swing angle θ of a conventional wheel-type construction vehicle as necessary.

Means for Solving the Problems In order to solve the above problems, the present invention takes the following means. That is, a. Between the lower traveling frame girder portion and the swingable wheel shaft, there are independent working-side oil chambers via a partition wall and upper and lower oil chambers for accommodating pistons are provided in series on the head side of a suspension cylinder and Each of the rod side,
Pivot to the left and right of the center of swing, b. A first piston having a rod connected to the lower traveling frame girder portion or a wheel shaft is provided in one oil chamber of the suspension cylinder, and is moved to the other piston in the other oil chamber when the first piston is moved to the first piston side. However, the second pistons provided with such protrusions that limit the stroke amount when the suspension cylinder moves in the contraction direction by a predetermined amount are respectively inserted and attached. A switching valve capable of arbitrarily shutting off the tank passage of the oil passage and supplying pressure oil from a hydraulic source in the middle of the oil passage in which the working-side oil chamber of the second piston oil chamber communicates with the oil tank. Is provided, and d. The respective oil passages in which the working-side oil chambers of the left and right first pistons communicate with the oil tank are closed independently of each other at the switching positions in which they communicate with each other, allowing only the supply of supplemental oil from the oil tank. A shut-off valve that can set the switching position is provided.

When pressure oil from the hydraulic source is applied to the working-side oil chamber of the second piston via the operation switching valve, the protrusion of the second piston moves in the direction of the first piston by a predetermined amount, and the first piston moves toward the first piston. Limit the stroke of the piston. Therefore, the left and right suspension cylinders have a maximum contracted length, and the swing angle of the wheel axle with respect to the lower traveling frame at this time is set to a value necessary for a normal wheel-type construction vehicle to travel on a normal traveling road surface at high speed. If you leave it, you can move safely.

Next, when the wheel-type construction vehicle runs at a low speed on a highly undulating ground or escapes from a soft ground, the switching valve is switched so that both of the working-side oil chambers of the second piston are in a position to communicate with the oil tank. If so, the protrusion of the second piston no longer restricts the stroke of the first piston, so that the minimum contracted length of the left and right suspension cylinders becomes small. As a result, the maximum swingable angle of the wheel shaft with respect to the lower traveling frame becomes large, and it is possible to cope with the above-mentioned bad location conditions.

Further, regardless of the switching position of the switching valve, the action of swinging and fixing the wheel shaft with respect to the lower traveling frame does not affect the setting position of the shut-off valve within the range of each limited stroke amount of the first cylinder. Of course, it can be selected according to.

Example Hereinafter, a detailed description will be given based on an example of the present invention.

FIG. 1 is a configuration diagram of the suspension system of the present invention. However, the same components as those described in FIG. In the drawing, 3 is a lower traveling frame of a wheel-type construction vehicle, 6 is a wheel shaft, 9 is an equalizer fixed to the wheel shaft 6, and 11 is a rotatable central girder hole of the lower traveling frame 3 and a center hole of the equalizer 9. A center pin that pivots to
Reference _numerals 12 _L and 12 _R are a pair of suspension cylinders that connect the girder left and right brackets of the lower traveling frame 3 and the left and right brackets of the equalizer 9 and are symmetrically arranged. The suspension cylinders 12 _L and 12 _{R have} the same structure on the left and right, but have stepped portions 26 _L and 26 _R in their cylinder tubes.
The first piston 27 _L each of the lower, 27 _R, but also are the second piston 28 _L, 28 _R is incorporated on its upper side. Therefore,
Above each piston, the first piston oil chamber as the working oil chamber
There are 29 _L and 29 _R and the second piston oil chambers 30 _L and 30 _R. Further, 31 is a switching valve, 32 is a hydraulic pump, 33 is a relief valve, 34
_L , 34 _R , 35, 36, 37, 38, 39, 40 are oil passages, and 25 is a swing joint for hydraulic and pneumatic circuits. FIG. 2 is a detailed sectional view of the left suspension cylinder 12 _L in FIG.
As shown in the drawing, there is a protrusion on the lower surface of the second piston, and the first piston when the second piston is above the drawing is from the position when the lower traveling frame 3 and the wheel shaft 6 are parallel to each other. In the direction in which the suspension cylinder contracts (S ₁
+ S ₂ ) movement stroke is allowed, but when pressure oil acts on the second piston oil chamber and the second piston descends until it contacts the stepped portion, the protrusion of the second piston causes the second piston oil chamber to move to the first piston oil. Only S ₂ enters the chamber, and as a result, the movable stroke of the first piston is reduced to S ₁ .

Next, the operation function of the suspension device of the present invention will be described. First
In the figure, when the pneumatic pressure changeover switch 22 is operated to the a position, the shutoff valve 17 is switched to the c position. At that time, the left and right suspension cylinders (hereinafter simply referred to as cylinders) 12 _L , 12 _R first piston chambers 29 _L , 29 _R
Are communicated with each other via the oil passages 34 _L , 34 _R and the throttle portion in the shut-off valve 17 in the section located at the position C, and are opened to the oil tank 21 via the oil passage 35. When the switching valve 31 is operated from this state to the E position, the discharge pressure oil of the hydraulic pump 32 passes through the oil passage 36, the E position of the switching valve 31, the oil passage 37, the oil passages 38 and 39, and the second piston oil chamber _30L. And 30 _R , the second piston 28 _L ,
The lower surface of 28 _R descends until it contacts the upper surfaces of the stepped portions 26 _L and 26 _R in the cylinder tube. At this time, the second piston 28 _L , 28
Length of the projecting portion of the lower surface of the _R is stepped portions 26 _L, 26 _R underside than S ₂ becomes long, that is, S projecting tip downward by ₂ to the first piston oil chamber 29 _L, 29 _R side It has a protruding size. Therefore, when the switching valve 31 is operated to the E position and the wheel shaft 6 is parallel to the lower traveling frame 3, the upper surfaces of the first pistons 27 _L and 27 _R and the downward protrusion of the second pistons 28 _L and 28 _R are projected. As shown in FIG. ₁ , there is an interval S ₁ between the lower end of the part and the lower end.

FIG. 3 is a rear front view of the lower traveling body traveling on the undulating ground with the changeover switch 22 and the changeover valve 31 of the construction vehicle set to the same operation position as in FIG. In the figure, the case where only the right tire 8 of the wheel shaft 6 rides on the convex portion of the ground will be described.
The right cylinder 12R of the center pin 11 trying to swing as the pivot center started contraction, but the pressure oil is generated in the first piston oil chamber 29 _R, piezoelectric oil oil passage 34 _R, shut Bofu valve 17
C position in the right section of the right cylinder 12 _R because it communicates with the first piston oil chamber 29 _L of the left cylinder 12 _L via the throttle in the section and the oil passage 34 _L , and also communicates with the oil tank 21. 2
The upper surface of the 7 _R until abuts the downward protrusion lower end of the second piston 28 _R, said right cylinder 12 _R is free to shrink. At that time, the inclination angle of the wheel shaft 6 with respect to the lower traveling frame 3 is θ.
_If it is set to ₁ , the same effect is exerted when the left cylinder _12L contracts, so that the maximum swingable angle of the wheel shaft 6 in FIG. 3 is + θ ₁ to −θ ₁ .

However, when self-propelled to escape from the ground having uneven undulations that cannot be accommodated by the maximum swingable angle + θ ₁ to −θ ₁ , it is necessary to increase the maximum swingable angle of the wheel shaft 6. . The method of the present application for coping with this will be described with reference to the drawings. In FIG. 4, the changeover switch 22 is operated to the a position and the shutoff valve 17 is changed to the c position to operate the changeover valve 31 to the f position. Thus, the left and right cylinder 12 _L and 12 30 second piston oil chamber each _{R L} and 3
0 _R communicates with the oil tank 21 via the oil passages 38, 39, the oil passage 37, the position of the switching valve 31, and the oil passage 40. As a result, the second piston 28 _L
And 28 _R are in a free state within the stroke range of the left and right second piston oil chambers 30 _L and 30 _R , respectively. Therefore, as shown in FIG. 4, when the right tire 8 of the wheel shaft 6 is in contact with the ground convex portion, the right cylinder 12 _R has the upper surface of the first piston 27 _R as the protruding portion of the lower surface of the second piston 28 _R. It contracts without being restricted until it comes into contact with the lower surface side of the cylinder tube inner stepped portion 26 _R. Accordingly, since the wheel shaft 6 to swing the center pin 11 of Ikoraida 9 as the pivot center, the distance between the first piston 27 upper surface and the cylinder tube stepped portion 26 _L bottom surface of the _L in the left cylinder 12 _L 2 X (S ₁ + S ₂ ) As a result, assuming that the horizontal level of the wheel shaft 6, that is, the inclination angle with respect to the lower traveling frame 3 is θ ₂ , the above-mentioned third
Since θ ₂ > θ ₁ compared to the tilt angle θ ₁ in the figure, the maximum swingable angle is expanded to + θ ₂ to −θ ₂ .

As described above, in the suspension system for a wheel shaft of the present invention, the first piston and the second piston are provided in the suspension cylinder mounted between the left and right brackets of the lower traveling frame girder and the left and right brackets of the wheel-type construction vehicle. And a piston. By operating the switching valve near the driver's seat, it is possible to select to connect the working-side oil chamber of the second piston to the hydraulic power source or the oil tank.

As a result, when the hydraulic pressure source is being passed to the working-side oil chamber of the second piston, the protrusion of the second piston limits the maximum stroke amount of the first piston to a predetermined value. The swingable angle of is + θ ₁ to −θ
The range becomes ₁ , and it is of course possible to safely drive at high speed on a normal road surface, and when the switching valve is switched so that the working-side oil chamber for the second piston communicates with the oil tank, the second piston Since the protruding portion of the first piston does not restrict the movement of the first piston, the maximum stroke amount of the first piston is expanded to the range where the piston is not mechanically restricted, and the wheel shaft can swing. The angle is θ ₁
The angle can be changed from + θ ₂ ° to −θ ₂ °, which is larger than °.

Therefore, in the vehicle shaft suspension device of the present invention, when the vehicle travels at a low speed on the ground with large ups and downs or escapes from a soft ground, the driver switches to the left and right second piston hydraulic oil chambers. By simply connecting to the oil tank and expanding the maximum swingable angle of the wheel shaft to + θ ₂ to −θ ₂ , the ground contact of the tires at the 4 front, rear, left and right positions is greatly improved, and troubles such as difficulty running or being unable to escape can be solved. It can be resolved.

[Brief description of drawings]

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. , Fig. 5 is an overall side view of the wheel type construction vehicle,
FIG. 6 is a view of the lower traveling body in FIG. 5 as seen from A, and FIG. 7 is a front view of a wheel axle suspension device of the prior art. 3,3 ′ …… Lower traveling frame 6 …… Wheel shaft 9 …… Equalizer 12 _L , 12 ′ _L …… Left suspension cylinder 12 _R , 12 ′ _R …… Right suspension cylinder 17 …… Shut-off valve 22 …… Switch Switch 27 _L , 27 _R ...... First piston 28 _L , 28 _R ...... Second piston 29 _L , 29 _R ...... First piston oil chamber 30 _L , 30 _R ...... Second piston oil chamber 31 ...... Switching valve

Claims (1)

[Claims] 1. A suspension system for a wheel-type construction vehicle in which a center hole of an equalizer on a wheel shaft is pivotally supported in a girder hole of a traveling frame by a center pin so as to be swingable in the left and right directions. A first piston that is provided in series and has a rod in one oil chamber and a protrusion in the other oil chamber that limits the stroke amount of the first piston when moved to the first piston side A pair of suspension cylinders provided with two pistons, which connects the girder portion and the wheel shaft, and an operating-side oil chamber of the second piston shuts off an oil passage leading to an oil tank to supply pressure oil from a hydraulic source. And a shut-off valve capable of closing the oil passages in which the working-side oil chambers of the left and right first pistons communicate with the oil tank, respectively. Do it Le-driven wheel shaft suspension device of a construction vehicle.