JPH025625B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a device for preventing abnormal tension in a track in a tracked working machine such as a hydraulic excavator or a bulltower.

(Prior Art) The lower running body of a crawler-equipped working machine is constructed as shown in FIG. That is, a driven wheel 42 is rotatably attached to one end of a side frame 44 that is a box-shaped structure via a bearing 46 that is movable back and forth, and a driven wheel 42 is rotatably attached to the other end by a hydraulic motor (not shown). A drive wheel 43 to be driven is rotatably attached, and an endless crawler track 41 is wrapped around the drive wheel 43 and the driven wheel 42, and the crawler track 41 is rotated by rollers 45 attached to a side frame 44. It is accepted.

As shown in FIGS. 5 and 6, between the vertical frame 44a of the side frame 44 and the yoke 47 that supports the bearing 46, there is a hydraulic cylinder 50 for buffering connected to the accumulator 14, and a hydraulic cylinder 50 for the crawler track 41. A cylinder 49 for adjusting tension is connected in series to form an adjuster cylinder 51. That is,
The piston rod 49b coupled to the piston 49a of the cylinder 49 is brought into contact with the vertical frame 44a of the side frame 44, and the piston 49a and the partition plate 52
A grease chamber B is formed between the piston 50a of the cylinder 50, and the piston rod 50b connected to the piston 50a of the cylinder 50 is brought into contact with the yoke 47, and a buffer oil chamber is formed between the piston 50a and the partition plate 52. A
The buffer oil chamber A is connected to the accumulator 14.

In this conventional configuration, the track 41 is attached to the driven wheel 42.
After winding, when grease is press-fitted into the grease chamber B by appropriate means, the tube of the adjuster cylinder 51, that is, the piston rod 50b moves to the left due to the pressure of the grease, and the yoke 47 supporting the driven wheel 42 is moved. Pushing outward, this also displaces the driven wheel 42 and tensions the track 41, the degree of tension varying depending on the pressure related to the amount of grease injected into the grease chamber B. In addition, if the crawler belt 41 bites into a rock or the like during running, and abnormal tension is generated in the crawler belt 41, or if the crawler belt 41 receives an impact, the piston rod 50b and the piston 50a
moves to the right, and the oil in the buffer oil chamber A flows into the accumulator 1.
4, the abnormal tension in the crawler track 41 is alleviated.

In such an adjuster cylinder, a buffering effect is provided by the pressure absorption effect of the accumulator 14, but as the pressure absorption effect of the accumulator 14 decreases as the usage period progresses,
The oil pressure in the buffer oil chamber A tends to become high, and the crawler track 41
There is a problem in that when an abnormal tension occurs in the cylinder, it cannot be absorbed, and the adjuster cylinder 51 and the surrounding structures or the vehicle body are damaged.

As a solution to this problem,
No. 29377 proposed a hydraulic circuit that detects the pressure in the grease chamber B or buffer oil chamber A and stops the working machine when this pressure exceeds a predetermined value. However, in this circuit, the buffer oil chamber A
If the cylinder 50 reaches the stroke end with the pressure of There is a risk of damage. In order to solve these drawbacks, the stroke of the cylinder 50 must be made sufficiently large, and the accumulator 14 must also have a correspondingly large capacity.

Further, the conventional hydraulic circuit has a problem in that as long as the pressures in chambers A and B are above a predetermined value, the vehicle stops running, and it takes time to return to a state where it can run again.

(Problems to be Solved by the Invention) The present invention has been made in view of these problems, and aims to prevent damage to the adjuster cylinder, etc. caused by the adjuster cylinder reaching its stroke end. It is an object of the present invention to provide a device for preventing abnormal tension in a crawler track, which is capable of quickly releasing a traveling stopped state due to tension in the crawler track caused by a rock or the like being caught in the crawler track.

(Means for Solving the Problems) The present invention provides for a driven wheel to be attached to one end of the left and right side frames constituting an undercarriage via a bearing that is movable in the front and back direction, and a crawler belt to be wound around the driven wheel. , a tracked working machine comprising a hydraulic adjuster cylinder for adjusting and buffering track tension between a yoke that supports the bearing and a side frame; a stroke end detection valve of the adjuster cylinder; A pilot valve as a control valve is provided, and the pilot valve serves as a pilot system for switching the pilot valve, in addition to a first pilot system connected to the traveling operation means, a pilot pressure oil is supplied when the stroke end detection valve is activated. The pilot valve has a first stage which is switched by operating the travel operating means in the forward or reverse direction, and a second stage which is switched by operating the travel operating means in the forward or reverse direction. and a second stage for forward and reverse travel, which is switched depending on the presence of pilot pressure in the pilot system, and in the second stage, the pilot pressure of the control valve becomes the tank pressure, and the reverse of the travel operation means It is characterized by having a hydraulic path configuration that enables reverse direction travel by directional operation, and when the crawler reaches the stroke end due to reasons such as the crawler biting into rocks etc. while traveling, the pilot Since the valve automatically moves to the second forward step, it does not stop traveling and continue traveling at the end of the stroke, preventing damage to the adjuster cylinder, etc. This makes it possible to quickly release rocks, etc. from the tracks and relieve abnormal tension.

(Embodiment) FIG. 1 shows an embodiment of the track abnormality tension prevention device according to the present invention, which includes a travel control hydraulic circuit.
The figure shows the mounting structure of the adjuster cylinder and its stroke end detection valve in this embodiment.

First, the structure of the adjuster cylinder 4 will be explained with reference to FIG. The adjuster cylinder 4 of this embodiment is a double-structured cylinder previously developed by the present invention, and the head side end plate 23a of the tube 23 is replaced by the vertical frame 44a of the side frame 44.
A support frame 24 having a rotation prevention mechanism (not shown) that is fitted into a ring-shaped support tube 22 provided at
It is supported and mounted by. A buffer oil chamber A of the adjuster cylinder 4 is filled with pressure oil, and the buffer oil chamber A is connected to an accumulator 14. A piston 25 is slidably accommodated in the tube 23 of the adjuster cylinder 4.
A hollow piston rod 26 is connected to the piston 25.

A piston 27 is slidably accommodated in the hollow piston rod 26, and a piston rod 28 is coupled to the piston 27 to form a double-structured cylinder. The piston 27 and the piston rod 28 integral therewith include the piston 2
Crawler tension adjustment fluid supply holes 29a and 29b that are inserted into the grease chamber B between 5 and 27 and communicate with each other.
is provided in the axial direction, and a fluid supply port 29c is provided on the side surface of the tip end of the piston rod 28, communicating with the fluid supply hole 29a and having a joint 30 attached thereto.
has been established. The tip of the piston rod 28 is engaged with a yoke 47 that supports the bearing 46 via a rotation prevention mechanism, but the details thereof will be omitted.

The hydraulic circuit for the accumulator 14 is a first
As shown in the figure, from the main pipes 53 and 54 between the traveling hydraulic motor 7 and its control valve 6, there is a shuttle valve 11 inserted between both pipes, and the pressure valve 1.
2 and a check valve 13, and when the oil pressure in the buffer oil chamber A reaches a predetermined value, the buffer is supplied to an oil tank (not shown) via a relief valve. In order to drain the oil from oil chamber A,
Measures have also been taken to prevent abnormal pressure.

In the adjuster cylinder 4 of FIG. 2, from the crawler belt 41 to the driven wheel 42, the bearing 46, and the yoke 47
The impact applied to the adjuster cylinder 4 through
The movement of the pressure oil in the buffer oil chamber A connected to the accumulator 14 to the accumulator 14 relieves the pressure and provides a buffering effect. In addition, as in this example, the adjuster cylinder 4 is a double cylinder,
By increasing the pressure-receiving area of the buffer oil chamber A, a large pressure-receiving pressure can be generated even at a relatively low pressure, and the length of the adjuster cylinder 4 as a whole can be shortened. In addition, if the tension of the crawler belt has loosened as the working machine has been used, the joint 30, fluid supply port 29c, and supply hole 29
By supplying grease (or pressurized oil) to the grease chamber B via a and 29b, the track tension can be restored.

The buffer oil chamber A of the adjuster cylinder 4 has a stroke end detection valve 3, which opens when the piston 25 of the adjuster cylinder 4 moves to a position near the stroke end, with respect to a pilot chamber 2a of the switch valve 2, which will be described later. Hydraulic piping 34A attached to the traveling body frame consisting of a side frame 44 and a track frame (not shown), a center joint 35 when a swing device is included, and a hydraulic piping 3 attached along the rotating body frame.
Connected via 4B.

The stroke end detection valve 3 is a cylinder that is fixed to the vertical frame 44a of the side frame 44 with bolts or the like, and has a distal end portion 36a fitted into a mounting hole provided in the end plate 23a of the adjuster cylinder 4. a valve body 36 having a shape;
A hollow valve body 37 is slidably housed in the tube 23 and has a tip 37a protruding into the tube 23 by, for example, several mm beyond the tube end plate 23a;
The valve main body 36 has a valve seat b in the middle thereof, and an oil passage a connected to the hydraulic pipe 34A. The body 37 has a tapered portion c corresponding to the valve seat b due to the force of the push spring 38, and the outer diameter of the tip 36a of the valve body 36 is smaller than the inner diameter of the tip 37a of the valve body 37. As a result, an oil passage d is formed between the two.

In FIG. 1, one side frame 44
As shown in FIG. 3, the other adjuster cylinder (not shown) is also provided with a stroke end detection valve 3 having a similar structure, and the piping 3
4A, a center joint 35, and a piping 34B to the pilot chamber 2a of the switch valve 2.

Next, the traveling control hydraulic circuit shown in FIG. 1 related to the switch valve 2 will be explained. 8 is a pilot hydraulic power source consisting of a hydraulic pump, a relief valve, etc. mounted on the working machine. Reference numeral 5 denotes a valved operation means having a travel operation lever, and includes a forward pilot valve 5a and a reverse pilot valve 5b.
1 is a control valve 6 for the traveling hydraulic motor 7;
This pilot valve is provided between the pilot chambers 6A, 6b and the operating means 5, and is a 9-port, 5-position switching valve, and has two pilot chambers 1a, 1b and 1c, 1d at both ends, respectively. The five positions of the pilot valve 1 include a neutral position C, a first forward position F1, a second forward position F2, and a first reverse position.
They are position B1 and second reverse position B2.

The first port a and the first port a on the primary side of the pilot valve 1
The 5P port e is connected to the secondary port of the switch valve 2 via a conduit 57, and the two primary ports of the switch valve 2 are connected to the conduit 58, respectively.
It is connected to the hydraulic power source 8 and the oil tank 10 via 59. Further, the second and fourth ports b and d of the pilot valve 1 are connected to the secondary ports of the pilot valves 5a and 5b of the operating means via pipes 60 and 61, respectively, and Road 6
2 and 63 respectively to the pilot chamber 1.
a, 1c. Further, the third port c of the pilot valve 1 is connected to the oil tank 10 via a conduit 64.

The first to fourth ports f to i on the secondary side of the pilot valve 1 are connected to the pilot chamber 1b, the pilot chambers 6a and 6b of the control valve 6, and the pilot chamber 1d via pipes 65 to 68, respectively. ing.

In the hydraulic circuit shown in FIG. 1, when the operating means 5 is in the non-operating state, the pilot chambers 6a, 6b of the control valve 6 communicate with the oil tank 10 via the pilot valve 1 and the pilot valves 5a, 5b of the operating means 5. Therefore, the hydraulic motor 7 is not driven. Now, when the forward pilot valve 5a is switched, pilot pressure oil from the hydraulic source 8 is supplied to the pilot chamber 1a of the pilot valve 1 via the pilot valve 5a and the pipes 60 and 62, so the pilot valve 6 is switched to the first position. As shown in Figure 3, the engine is switched to the first forward position F1, pilot pressure oil is supplied to the pilot chamber 6a of the control valve 6 via the pilot valves 5a and 1, and the control valve 6 is switched to the upper position in the figure. As a result, the travel hydraulic motor 7 rotates in the forward direction. On the other hand, when the reverse pilot valve 5b is switched, the pilot valve 1 is switched to the first reverse position B1, and the pilot pressure oil from the pilot hydraulic pressure source 8 flows into the pilot chamber 6 of the control valve 6.
b, the control valve 6 is switched to the upper position in the figure, and the travel hydraulic motor 7 is rotated in the reverse direction.

Here, as shown in FIG.
is in the F1 position and the work machine is moving forward, ports a and f communicate with each other, so the pipe line 57 connected to the switch valve 2 communicates with the pilot chamber 1b via the pilot valve 1 and the pipe line 65. There is.
Here, when the stroke end detection valve 3 is in the non-operating position as shown in the figure, no pressure oil is supplied from the accumulator 14 to the pilot chamber 2a of the switch valve 2, so the valve is in the pressure oil cutoff position as shown in the figure. . Therefore, the pilot valve 1 is held at the F1 position shown.

Now, while the work machine is being moved forward by operating the forward pilot valve 5a, the crawler track 41
The crawler track 41 becomes bent due to foreign objects such as stones being caught in the track, causing abnormal tension in the track track 41, and the piston 25 causes the valve body 3 to bend.
7 is pushed against the force of the push spring 38, a gap opens between the valve seat b and the tapered part c, and the pressure oil in the buffer oil chamber A flows into the passages d and a of the stroke end detection valve 3. , is supplied to the pilot chamber 2a of the switch valve 2 via the pipes 34A and 34B, and the switch valve 2 is switched from the left position to the right position in FIG. As a result, pilot pressure oil from the pilot oil pressure source 8 is supplied to the pilot chamber 1b of the pilot valve 1 through the switch valve 2, and the pilot valve 1 moves from the forward first position F1 shown in the figure to the second forward position F1 shown in FIG. Switch to position F2. Therefore, the pipes 60 and 66 are cut off, the pilot chamber 6a is communicated with the oil tank 10 via the pipe 66, ports g and c, and the pipe 64, and the control valve 6 is in the neutral position shown in FIG. It returns to its position and stops moving forward.

Here, at the F2 position in FIG. 4, the ports d and h of the pilot valve 1 are in communication, so the pilot chamber 6b of the control valve 6 can be operated via the pipe 67, the pilot valve 1, and the pipe 61. Since the means 5 is in communication with the reverse pilot valve 5b, when the reverse pilot valve 5b is operated, pilot pressure oil is supplied to the pilot chamber 6b, the control valve 6 is switched to the lower position, and the hydraulic motor 7 is operates in the backward direction and the working machine moves backward, so rocks and the like are released from the crawler track 41 and the abnormal tension in the track 41 disappears.

When the abnormal tension disappears, adjuster cylinder 4
The force pressing the piston rod 28 decreases and moves to the left in the drawing, causing the piston 25 to press against the valve body 37.
, the stroke end detection valve 3 closes, and the switch valve 2 returns to the right position.

Figures 3 and 4 show an example in which abnormal tension in the track occurs when moving forward, and the abnormal tension is relieved by moving backward, but if abnormal tension occurs in the track while moving backward, moving it forward It can relieve abnormal tension.

In this way, when the adjuster cylinder 4 reaches the stroke end, the oil in the buffer oil chamber A is added to the pilot chamber 2a of the switch valve 2 via the stroke end detection valve 3 and the hydraulic piping 34A, 34B. Switch 2,
This moves the pilot valve 1 from F1 to F2 position.
Alternatively, by switching from the B1 position to the B2 position and setting the oil pressure in the pilot chambers 6a and 6b of the control valve 6 to the tank pressure, the control valve 6 is placed in the neutral position and the working machine is stopped. This prevents the vehicle from continuing to drive with the cylinder 4 contracted to the end of its stroke, thereby preventing damage to the adjuster cylinder and surrounding structures, as well as damage to the vehicle body.

Furthermore, if abnormal tension in the crawler belt occurs during running, the abnormal tension can be released by performing an operation for running in the opposite direction, so that the abnormal tension in the crawler track can be quickly released.

Furthermore, when carrying out the present invention, the switch valve 2 may be installed near the adjuster cylinder 4, but in that case, the piping 58, 59 connected to the primary port of the switch valve 2 and the secondary piping 57 must be disposed on the side frame 44. On the other hand, as in this embodiment, by opening the stroke end detection valve 3 by the movement of the valve body 37, the pressure oil in the buffer oil chamber A is led out through the pipe 34A, and this is used as the pilot pressure oil for stopping the travel. By using the configuration used as a hydraulic pump, only one hydraulic piping is required for each of the left and right side frames 44, and the hydraulic piping is simplified.

In the above embodiment, the stroke end detection valve 3 is attached to the end plate 23a, but it may be attached directly to the bottom of the adjuster cylinder 4. In addition, stroke end detection is
For example, a configuration may be adopted in which a movable body such as a rod is connected to the piston rod 26 and the movable body opens the stroke end detection valve 3. In this case, the stroke end detection valve 3 is provided in the middle of the hydraulic piping 34A. Furthermore, the pilot valve 1 is not constituted by one spool or one valve, but may be constituted by two or more valves.

(Effects of the Invention) As described above, in the track abnormality tension prevention device of the present invention, when the piston of the adjuster cylinder moves to the vicinity of the stroke end, the stroke end detection valve is actuated by the piston or a movable body interlocked with the piston. As a result, the pilot valve is switched and the control valve is switched to stop the work machine, which prevents the adjuster cylinder from continuing to travel with the adjuster cylinder contracted to the end of its stroke, and prevents the adjuster cylinder and its Damage to surrounding structures is prevented, and damage to the vehicle body is also prevented.

In addition, if abnormal tension in the track occurs during driving, the abnormal tension can be relieved by running in the opposite direction, so compared to waiting for natural recovery, the abnormal tension in the track can be removed more quickly. I can solve it.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the track abnormal tension prevention device according to the present invention, FIG. 2 is a sectional view showing the mounting structure of the adjuster cylinder and stroke end detection valve in this embodiment, and FIG. FIG. 4 is a circuit diagram explaining the operation of the embodiment, and FIG.
The figure is a side view of a traveling body illustrating a conventional adjuster cylinder, and FIG. 6 is a sectional view showing details of the conventional adjuster cylinder.

Claims (1)

[Claims] 1. A driven wheel is attached to one end of the left and right side frames constituting the lower traveling body via a bearing that is movable in the front and back direction, and a crawler track is wrapped around the driven wheel, and a track is installed between the yoke that supports the bearing and the side frame. In a work machine with a track, which is provided with a hydraulic adjuster cylinder for adjusting track tension and buffering, a stroke end detection valve of the adjuster cylinder;
The pilot valve is equipped with a pilot valve as a control valve for the traveling body, and the pilot valve serves as a pilot system for switching the pilot valve, in addition to a first pilot system connected to the traveling operation means, which controls the pilot pressure when the stroke end detection valve is actuated. It has a second pilot system to which oil is supplied, and the pilot valve has a first stage that is switched by operating the traveling operating means in the forward or reverse direction, and a first stage that is switched by operating the traveling operating means in the forward or reverse direction. and a second stage for forward and reverse travel, which is switched depending on the presence of pilot pressure in the second pilot system, and in the second stage,
A device for preventing abnormal tension in a crawler track, characterized in that the pilot pressure of the control valve is equal to the tank pressure, and the hydraulic circuit is configured such that reverse direction travel is possible by operating the travel operation means in the reverse direction.