JPH0240552B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an adjuster cylinder hydraulic circuit provided in a side frame as a tension adjustment and shock absorbing device for a crawler track in a tracked work machine such as a hydraulic shovel 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 2 is rotatably attached to one end of the side frame 4, which is a box-shaped structure, via a bearing 6 that can move back and forth, and a driven wheel 2 is attached to the other end by a hydraulic motor (not shown). A drive wheel 3 to be driven is rotatably mounted, and an endless crawler track 1 is wrapped around the drive wheel 3 and driven wheel 2, and the crawler track 1 is rotated by rollers 5 attached to a side frame 4. It is accepted.

As shown in FIGS. 4 and 5, between the vertical frame 4a of the side frame 4 and the yoke 7 that supports the bearing 6, there is a hydraulic cylinder 10 for buffering connected to the accumulator 8, and a hydraulic cylinder 10 for the crawler track 1. The cylinder 9 for adjusting tension is connected in series to form an adjuster cylinder 11. That is, the piston rod 9b connected to the piston 9a of the cylinder 9 is
A grease chamber B is formed between the piston 9a and the partition plate 12 by contacting the vertical frame 4a of the side frame 4, while the piston rod 10b connected to the piston 10a of the cylinder 10 is connected to the yoke 7.
A buffer oil chamber A is formed between the piston 10a and the partition plate 12, and the buffer oil chamber A is connected to the accumulator 8.

In this conventional configuration, after the crawler belt 1 is wound around the driven wheel 2, when grease is press-fitted into the grease chamber B by an appropriate means, the tube of the adjuster cylinder 11, that is, the piston rod 10b moves to the left due to the pressure of the grease. 2, which pushes the yoke 7 supporting the driven wheel 2 outward, thereby also displacing the driven wheel 2 and tensioning the track 1, the degree of tension being dependent on the pressure related to the amount of grease injected into the grease chamber B. It changes accordingly. In addition, if the crawler track 1 gets caught in a rock or the like during running and abnormal tension is generated in the track 1, or if the track 1 receives an impact, the piston rod 1
0b and the piston 10a move to the right, and the oil in the buffer oil chamber A escapes to the accumulator 8, so the crawler track 1
abnormal tension is alleviated.

In such an adjuster cylinder, a buffering effect is performed by the pressure absorption effect of the accumulator 8. However, as the pressure absorption effect of the accumulator 8 decreases over time, the oil pressure in the buffer oil chamber A decreases. The tension tends to become high, and if abnormal tension occurs in the crawler track 1, it cannot be absorbed, resulting in damage to the adjuster cylinder 11 and surrounding structures or the vehicle body.

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 10 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 10 must be made sufficiently large, and the accumulator 8 must also have a correspondingly large capacity.

Therefore, the present inventors provided an on-off valve that is switched by the piston of the adjuster cylinder when the piston moves to a position near the stroke end, and connected the on-off valve to the operating circuit of the traveling body by connecting a hydraulic pipe to the operating circuit of the traveling body. We have developed a configuration in which the on-off valve opens and operating pressure oil is supplied to the switching valve of the operating circuit, stopping the work equipment when the piston of the adjuster cylinder moves to a position near the stroke end. , proposed as patent application No. 189834.

According to this hydraulic circuit, it is possible to prevent the travel from continuing with the adjuster cylinder contracted to the end of its stroke, so it is possible to provide a buffering effect that effectively utilizes the entire stroke of the adjuster cylinder. Therefore, there is no need to provide an extra stroke as in the conventional case, and a compact adjuster cylinder can be realized, and the accumulator can also be made smaller.

However, this prior application requires a total of three pipes for the on-off valve: two pipes for returning and returning pilot pressure oil, and one pipe for the tank port. There is a problem.

(Problems to be Solved by the Invention) The present invention has been made in view of the above-mentioned problems. There is no risk of damage to the adjuster cylinder due to reaching the stroke end.
An object of the present invention is to provide an adjuster cylinder hydraulic circuit for a crawler-equipped work machine that does not require complicated hydraulic piping attached to a side frame, as proposed in the above issue.

(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 work machine comprising a hydraulic adjuster cylinder for adjusting track tension and buffering between a yoke supporting the bearing and a side frame, wherein an on-off valve is provided at an end of the adjuster cylinder; The on-off valve has a hollow valve body, and the valve body is movably inserted into the end plate of the adjuster cylinder and installed so that its tip slightly protrudes into the cylinder from the inner surface of the end plate. A configuration in which a push spring that presses the valve body toward an adjuster cylinder side is provided, and the valve body opens the opening/closing valve by a piston of the adjuster cylinder at the end of a stroke of the adjuster cylinder against the force of the push spring. The present invention is characterized in that the hydraulic pipe for deriving the buffer pressure oil connected to the on-off valve is connected to the pilot chamber of the switch valve for stopping the work machine running on the work machine main body.

(Function) Since the present invention has the above structure, the valve body of the on-off valve is pushed by the piston of the adjuster cylinder against the force of the push spring at the end of the stroke of the adjuster cylinder, so that the on-off valve opens.
The switch valve is activated by the buffer pressure oil, and the work equipment stops running.

(Embodiment) Fig. 1 shows an embodiment of the adjuster cylinder hydraulic circuit according to the present invention including a travel control hydraulic circuit, and Fig. 2 shows the mounting structure of the stroke end detection device of the adjuster cylinder in this embodiment. It shows.

First, according to FIG. 2, adjuster cylinder 19
Explain the structure of The adjuster cylinder 19 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 connected to the vertical frame 4a of the side frame 4.
The tube 23 is fitted into a ring-shaped support tube 22 provided in the side frame 4, and the other end of the tube 23 is supported by a support frame 24 having a rotation prevention mechanism (not shown) fixed to the side frame 4. A buffer oil chamber A of the adjuster cylinder 19 is filled with pressure oil, and the buffer oil chamber A is connected to the accumulator 8. A piston 25 is slidably accommodated in the tube 23 of the adjuster cylinder 19.
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 communicate with 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 the yoke 7 that supports the bearing 6 via a detent mechanism, but the details thereof will be omitted.

Although the illustration of the hydraulic circuit for the accumulator 8 is omitted, for the accumulator 8,
Pressure oil can be supplied from the main circuit via the pressure reducing valve, and when the oil pressure in the buffer oil chamber A reaches a predetermined value, the oil in the buffer oil chamber A is supplied to the oil tank 21 via the relief valve. Measures have also been taken to prevent abnormal pressures.

In the adjuster cylinder 19 shown in FIG. 2, the impact applied to the adjuster cylinder 19 from the crawler track via the driven wheel 2, bearing 6, and yoke 7 is applied to the pressure oil accumulator in the buffer oil chamber A connected to the accumulator 8. The movement to 8 provides a buffering effect. In addition, as in this example, the adjuster cylinder 19 is a double cylinder, and the buffer oil chamber A
By increasing the pressure-receiving area of the adjuster cylinder 19, a large pressure-receiving pressure can be generated even at a relatively low pressure, and the length of the adjuster cylinder 19 as a whole can be shortened. In addition, if the tension in the tracks has loosened over the period of use of the working machine, the joint 3
0. By supplying grease (or pressure oil) to the grease chamber B through the fluid supply port 29c and the supply holes 29a and 29b, the track tension can be restored.

The buffer oil chamber A of the adjuster cylinder 19 is
Pilot chamber 20a of the switch valve 20 described later
On the other hand, the piston 25 of the adjuster cylinder 19
An on-off valve 31 that opens when the vehicle moves to a position near the stroke end, a hydraulic piping 34A attached to a traveling body frame (see FIG. 3) consisting of a side frame 4 and a track frame 40, and a swing device 4.
1, the center joint 35, the shuttle valve 42, and the hydraulic piping 34 attached along the revolving body frame are connected to each other.

The on-off valve 31 is connected to the vertical frame 4 of the side frame 4.
A cylindrical valve body 36 is fixed to a with a bolt or the like, and has a tip 36a fitted into a mounting hole provided in the end plate 23a of the cylinder 19.
A hollow valve body 37 is slidably housed in the valve body 36 and has a tip 37a protruding into the tube 23 by, for example, several mm from the tube end plate 23a. It consists of a pressing spring 38 that presses against the star cylinder 19 side, and
The valve body 37 has a valve seat b in its intermediate portion and an oil passage a connected to the hydraulic pipe 34A, and the valve body 37 has a tapered portion that comes into contact with the valve seat b by the force of the push spring 38. c, and the tip portion 36 of the valve body 36 is smaller than the inner diameter of the tip portion 37a of the valve body 37.
Due to the small outer diameter of a, there is an oil passage d between them.
is formed.

Although FIG. 1 shows the adjuster cylinder 19 provided on one side frame 4, as shown in FIG. is provided, and the above-mentioned switch valve 20 is connected via piping 34A, center joint 35, piping 34B, shuttle valve 42 and piping 34.
It is commonly connected to the pilot chamber 20a of the two pilot chambers 20a, and is also connected to the oil tank 21 via a throttle valve 39. This throttle valve 39 is connected to the pilot chamber 20a.
When pressurized oil is supplied from the buffer oil chamber A to the oil tank 21, the flow to the oil tank 21 is restricted to ensure that the oil pressure has the amount of restriction necessary to switch the switch valve 20, and When the piston of the star cylinder 19 returns from the stroke end position to the original position and the on-off valve 31 is closed, the oil in the pilot chamber 20a of the switch valve 20 is flowed into the oil tank 21 to adjust the oil pressure in the hydraulic piping 34A, 34B. It is provided to prepare for the next operation by adjusting the tank pressure.

Next, the travel control hydraulic circuit shown in FIG. 1 related to the switch valve 20 will be explained. 13 is a pilot hydraulic power source consisting of a hydraulic pump, a relief valve, etc. mounted on the work machine, and 14 is a travel hydraulic motor driven by pressure oil in the main circuit, which is installed near the drive wheels of the side frame 4. be. A control valve 15 is inserted into the main circuit to control forward/reverse rotation and stop of the travel hydraulic motor 14, and pilot chambers 15a and 15b are provided on both sides of the control valve. 16 is a pilot valve, forward pilot valve 1
6a and a reverse pilot valve 16b.
17a and 17b are shuttle valves that select the high pressure side;
Reference numeral 18 denotes a switching valve provided for forced stop of travel, and its pilot chamber 18p is connected to the secondary port of the switch valve 20.

The two primary ports of the switching valve 18 are connected to the pilot oil pressure source 13 and the oil tank 21, respectively, and the secondary ports are connected to the shuttle valves 17a,
17b, and the other primary port of each shuttle valve 17a, 17b is connected to the forward pilot valve 16.
a and the reverse pilot valve 16b, and each shuttle valve 17a, 17
The secondary side port of b is connected to the control valve 15.
are connected to pilot chambers 15a and 15b, respectively.

In the hydraulic circuit shown in FIG. 1, when the forward pilot valve 16a is operated to switch, the forward pilot valve 16a is switched from the lower position to the upper position in the diagram, and the pilot hydraulic power source 13
Pilot pressure oil from the control valve 15 enters the pilot chamber 15a of the control valve 15 via the shuttle valve 17a.
The control valve 15 is switched to the upper position in the figure, and the travel hydraulic motor 14 rotates in the forward direction. On the other hand, the reverse pilot valve 16b
When the switch is operated, the control valve is switched from the lower position in the figure to the upper position, and the pilot hydraulic pressure from the pilot hydraulic pressure source 13 is supplied to the pilot chamber 15b of the control valve 15 via the shuttle valve 17b, and the control valve 15 is moved to the position shown in the figure. Switching to the upper position, the traveling hydraulic motor 14 rotates in the reverse direction.

When the switch valve 20 is in the inoperative position, that is, in the right position in the figure, the pilot chamber 18p of the switching valve 18 communicates with the oil tank 21 via the switch valve 20, so the shuttle valve 17a,
One primary side port of 17b communicates with the oil tank 21 via the switching valve 18. Therefore, by operating the pilot valves 16a and 16b, the control valve 15 is switched as described above.

Here, while the work machine is being moved forward by operating the forward pilot valve 16a,
When the crawler track gets caught in a foreign object such as a stone and bends, the track becomes abnormally tense, and when the valve body 37 is pushed by the piston 25 against the force of the push spring 38, the gap between the valve seat b and the tapered part c A gap opens in the buffer oil chamber A.
Pressure oil flows through the passages d and a of the on-off valve 31 and the piping 34.
A and 34B are supplied to the pilot chamber 20a of the switch valve 20, and the switch valve 20 is switched from the right position to the left position in FIG. As a result, pilot pressure oil from the pilot oil pressure source 13 is supplied to the pilot chamber 18p of the switching valve 18 through the switch valve 20, and the switching valve 18 is switched from the upper position to the lower position as shown in the figure. From the switching valve 18, the shuttle valve 17a, 1
Pilot pressure oil is supplied to the pilot chambers 15a, 15b on both sides of the control valve 15 through the control valve 15, the control valve 15 is brought to the neutral position, the traveling hydraulic motor 14 is stopped, and the working machine is also stopped.

Here, abnormal tension in the crawler track is caused by running, so by stopping running,
Abnormal tension also disappears. When the abnormal tension disappears, the force pressing the piston rod 28 of the adjuster cylinder 19 decreases and moves to the left in the drawing, causing the piston 25 to separate from the valve body 37, closing the on-off valve 31, and moving the switch valve 20 to the right position. Since the switching valve 18 returns to the upper position shown in the figure, the travel motor 14 can be rotated in the forward or reverse direction by operating the pilot valves 16a and 16b.

In this way, when the adjuster cylinder 19 reaches the stroke end, the oil in the buffer oil chamber A is released from the on-off valve 3.
1 and the pilot chamber 20a of the switch valve 20 through the hydraulic pipes 34A and 34B, thereby switching the switch valve 20, thereby switching the switching valve 18, and controlling the control valve 1.
Hydraulic pressure is applied to the pilot chambers 15a and 15b at both ends of the control valve 15 so that the control valve 15 is in the neutral position and the work machine is stopped.
This prevents the vehicle from continuing to drive with the adjuster cylinder 19 contracted to the end of its stroke, thereby preventing damage to the adjuster cylinder and the surrounding structures, as well as damage to the vehicle body.

Furthermore, if the switch valve 20 is installed near the adjuster cylinder 19, the piping 45, 4 connected to the primary port of the switch valve 20
6 and the secondary side piping 47 must be disposed on the side frame 4, but by opening the on-off valve 31 by the movement of the valve body 37 as in the present invention,
By drawing out the pressure oil from the buffer oil chamber A through the pipe 34A and using it as pilot pressure oil for stopping the vehicle, there is only one hydraulic pipe installed in each of the left and right side frames 4. fruit,
Hydraulic piping is simplified.

In the above embodiment, the pilot hydraulic pressure is applied to the pilot chambers 15a and 15b on both sides of the control valve 15 when the switch valve 20 is operated.
In the pipes 43a and 43b connected to the pipes a and 15b,
When the switch valve 20 is not in operation, the pilot chambers 15a and 15b are communicated with the respective secondary ports of the pilot valves 16a and 16b,
When working on the switch valve 20, the same effects as in the previous embodiment can be achieved even if switching valves are provided to communicate the pilot chambers 15a, 15b with the oil tank 21, respectively.

Further, in the above embodiment, an example was shown in which the on-off valve 31 was attached to the end plate 23a, but it may be attached directly to the bottom of the adjuster cylinder 19.
Furthermore, for the detection of the stroke end, 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 opening/closing valve 31 is opened by the movable body.
In this case, the on-off valve 31 will be provided in the middle of the hydraulic piping 34A.

(Effects of the Invention) As described above, in the hydraulic circuit of the adjuster cylinder of the present invention, when the piston of the adjuster cylinder moves to the vicinity of the stroke end, the piston or the movable body interlocked with the piston opens the on-off valve. The buffering pressure oil of the adjuster cylinder was led outside through hydraulic piping, and the pressure oil was used as pilot pressure oil to switch the grass diversion valve and stop the work machine. As in the disclosed circuit, if the adjuster cylinder reaches its stroke end when the pressure in the buffer oil chamber is below a predetermined value, the working machine will not stop and the adjuster cylinder will not provide a buffering effect. There is no risk of occurrence. Therefore, according to the present invention, even if the adjuster cylinder reaches the stroke end with the pressure in the buffer oil chamber being below a predetermined value, there is no risk of damage to the adjuster cylinder and the surrounding structures. . Also,
There is no need to increase the stroke of the adjuster cylinder or increase the capacity of the accumulator connected to the buffer oil chamber, and the device can be made more compact.

Further, according to the present invention, similarly to the circuit disclosed in JP-A No. 60-29377, it is only necessary to provide one pilot hydraulic piping for stopping the running of the working machine for each of the left and right side frames. 1986-
Compared to the circuit proposed in No. 189834, the hydraulic piping provided on the side frame is simplified and can be manufactured at low cost, and the number of parts attached to the side frame is reduced, making maintenance and inspection easier.

The present invention can also be applied to a case where the working machine main body is installed non-rotating on the undercarriage, but in particular, the upper revolving structure is placed on the undercarriage via a swing device, and the upper revolving structure is mounted on the upper revolving structure. When the hydraulic circuit connected to the hydraulic piping is connected, there is an advantage that the number of circuits connected via the center joint is reduced, and the structure of the center joint is also simplified.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing one embodiment of the adjuster cylinder hydraulic circuit according to the present invention, FIG. 2 is a sectional view showing the mounting structure of the adjuster cylinder and on-off valve in this embodiment, and FIG. 3 is the embodiment. Fig. 4 is a plan view illustrating the arrangement structure of the hydraulic piping; Fig. 4 is a side view of the traveling body illustrating the conventional adjuster cylinder;
FIG. 5 is a sectional view showing details of a 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, an on-off valve is provided at an end of the adjuster cylinder, the on-off valve has a hollow valve body, and the valve has a hollow valve body. a push spring whose body is movably inserted into the end plate of the adjuster cylinder so that its tip projects slightly into the cylinder from the inner surface of the end plate, and which presses the valve body toward the adjuster cylinder side of the on-off valve; and has a structure in which the valve element opens the on-off valve by the piston of the adjuster cylinder against the force of the push spring at the end of the stroke of the adjuster cylinder, and a buffer connected to the on-off valve. An adjuster cylinder hydraulic circuit for a tracked working machine, characterized in that a hydraulic piping for deriving pressure oil is connected to a pilot chamber of a switch valve for stopping the running of the working machine on the main body of the working machine.