JPH09166104A - Hydraulic cylinder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lighten a shock at stopping a piston on a cylinder end and enable the piston to impulsively stop if necessary by providing a connecting oil passage bypassing a cushioning oil passage and connecting together an oil chamber on the moving end part side and an oil drain passage capably of being opened or closed. SOLUTION: In the case of an ordinary bucket work such as excavation or conveyance, an opening/closing valve 25 is in the closed state so as to close a connecting oil passage 24. In this state, when a piston 12 is moved up to a cylinder end on the head cover 16 side, oil in a cushioning chamber 22 is drained in a state of being restricted, a shock at stopping the piston on the cylinder end is lightened, and a quiet work of little vibration can be executed. Meanwhile, in the case such as letting fall soil stuck on a bucket, the opening/ closing valve 25 is opened so as to open the connecting oil passage 24. In this state, oil in the cushioning chamber 22 is drained through the connecting oil passage 24 without being restricted, the piston 12 is impulsively stopped, and hence soil and the like stuck to the bucket can be let fall. Consequently, workability is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of hydraulic cylinders provided in construction machines and the like.

[0002]

2. Description of the Related Art Generally, in this type of hydraulic cylinder, in order to mitigate the impact when the piston moves to the end of the cylinder barrel and stops, the oil discharged from the oil chamber on the piston moving side is squeezed. Some have a cushion oil passage for suppressing the moving speed. An example of such a device is shown in FIG. 5, for example.
A cushion chamber 22 having a small diameter is formed at the end of the cylinder cylinder 11, while a cushion is fitted into the piston 12 in a state having a gap S in the cushion chamber 22 when the piston 12 moves to the end of the cylinder cylinder. Plunger 2
3 is provided, and when the cushion plunger 23 is fitted into the cushion chamber 22, the oil in the cushion chamber 22 is discharged through the gap S (the gap S corresponds to the cushion oil passage) to move the piston. It is configured to suppress the speed.

[0003]

By the way, when the hydraulic cylinder provided with the cushion oil passage is used as a bucket cylinder provided in, for example, a hydraulic excavator, the cylinder end is used when carrying out normal bucket work such as excavation and transportation. It is convenient because the impact at the time of stopping at the bucket can be mitigated, and noise and vibration can be reduced, but there are times when you want to stop the bucket shockly to remove the dirt and other substances adhering to the bucket. In such a case, there is a problem that the cushion oil passage is an obstacle and it is not possible to perform a shock stop, and there is a problem to be solved by the present invention.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances in order to solve these problems, and a piston to be movably fitted in a cylinder is provided. A hydraulic cylinder provided with a cushion oil passage that restricts the moving speed of the piston by throttling the oil discharged from the moving end side oil chamber as the cylinder moves to the end of the cylinder. A connection oil passage that connects the moving end side oil chamber and the oil discharge passage so as to be opened and closed is provided so as to bypass the cushion oil passage. Further, according to the present invention, as the piston movably fitted in the cylinder cylinder moves to the end of the cylinder cylinder, the displacement speed of the piston is suppressed by squeezing the oil discharged from the moving end side oil chamber. A hydraulic cylinder provided with a cushion oil passage may be provided with an opening means for opening the throttle of the cushion oil passage. By doing so, the impact of stopping the piston at the cylinder end can be alleviated and noise and vibration can be reduced, but the movement speed of the piston can be suppressed by opening the connecting oil passage or cushion oil passage. It will also be possible to stop without doing so. This hydraulic cylinder can be adopted as, for example, a bucket cylinder provided in a construction machine.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings. In FIG. 1, reference numeral 1 is a hydraulic excavator, and the hydraulic excavator 1 includes a crawler type lower traveling body 2, an upper swinging body 3 swingably supported above the lower traveling body 2, and an upper swinging body 3. The front attachment 4 is attached to the front part of the front attachment 4 and the like. Further, the front attachment 4 has a boom 5 whose base end is swingably supported by the upper swing body 3, and a tip end of the boom 5. An arm 6 swingably attached to the arm 6, a bucket 7 swingably attached to the tip of the arm 6, a boom 5, an arm 6, and hydraulic cylinders 8, 9, 10 for swinging the bucket 7. The present invention is embodied in the hydraulic cylinder 10 for the bucket 7, though it is the same as in the prior art in that it is composed of each member.

The hydraulic cylinder 10 for the bucket 7 is
A cylindrical cylinder tube 11, a piston 12 movably fitted in the cylinder tube 11, a base end portion is fixed to the piston 12, and a tip end portion is connected to the bucket 7 via a link mechanism 13. Piston rod 14, cylinder cylinder 1
No. 1 head-side opening and a head cover 16 connected to the arm 6 via a bracket 15, a rod cover 17 closing the rod-side opening of the cylinder cylinder 11, and head-side oil formed on both sides of the piston 12. Chamber 18,
The rod-side oil chamber 19 is composed of various parts such as a head-side port 20 and a rod-side port 21 formed in the cylinder cylinder 11 for supplying and discharging pressure oil to the oil chambers 18, 19. The hydraulic cylinder 10 is provided with the head side port 2
0 or the pressure of the pressure oil supplied from the rod side port 21 causes the pinton 12 to move the rod cover 1 inside the cylinder cylinder 11.
It moves to the 7 side or the head cover 16 side and expands and contracts by the movement of the piston rod 14 which is integral with this.

Further, 22 is a cushion chamber formed in the head cover 16, and the inner diameter of the cushion chamber 22 is set smaller than the inner diameter of the cylinder cylinder 11. Reference numeral 23 denotes a cushion plunger that is provided so as to project from the side surface of the head of the piston 12. The cushion plunger 23 is provided with the cushion chamber 22 as the piston 12 moves to the cylinder end on the head cover 16 side of the cylinder cylinder 11. It is set so as to be fitted in with a gap S in.

On the other hand, 24 is a connecting oil passage for connecting the cushion chamber 22 and the head side port 20, and an electromagnetic on-off valve 25 is provided in the connecting oil passage 24. This open / close valve 25 is a switch 2 provided in the cockpit section 26.
Based on the ON-OFF switching of No. 7, it is set to switch between the open state in which the connecting oil passage 24 is opened and the closed state in which it is closed.

When the piston 12 moves to the cylinder end on the head cover 16 side of the cylinder cylinder 11 and the cushion plunger 23 is fitted into the cushion chamber 22, the cushion chamber 22 is closed when the connecting oil passage 24 is closed. Oil is discharged from the head-side port 20 through the gap S (the gap S corresponds to the cushion oil passage of the present invention), whereby the discharged oil is throttled and the piston 12 Is suppressed, and the impact at the time of stopping the piston 12 at the cylinder end can be alleviated. On the other hand, when the connection oil passage 24 is open, the oil in the cushion chamber 22 is discharged to the head-side port 20 without being throttled through the connection oil passage 24. Stopping is performed in a state where the movement speed of 12 is not suppressed.

In the case of the construction described above, when the usual bucket work such as excavation and transportation is performed, the opening / closing valve 25 is closed and the connecting oil passage 24 is closed. In this state, when the piston 12 moves to the cylinder end on the side of the head cover 16, the oil in the cushion chamber 22 is squeezed and discharged as described above.
The impact at the time of stopping at the cylinder end is alleviated, and the work can be performed quietly and with little vibration.

On the other hand, when it is desired to stop in a state where the impact is not relieved due to dropping the soil adhered to the bucket 7, the on-off valve 25 is opened and the connecting oil passage 24 is opened. In this state, as described above, the oil in the cushion chamber 22 is discharged without being throttled through the connecting oil passage 24, so that the moving speed of the piston 12 is not suppressed and the shock is stopped. It is possible to drop the soil or the like attached to the bucket 7 by the impact.

As a result, although the cushion oil passage for cushioning the impact is provided, when the dirt adhering to the bucket 7 is dropped, the connecting oil passage 24 is opened by opening the connecting oil passage 24. Since the oil is discharged via the, it is possible to stop in a state where the impact is not alleviated, and the workability is improved.

The present invention is not limited to the above-mentioned first embodiment, and as in the second embodiment shown in FIG. 3, the head side port 20 and the cushion chamber 22 are provided.
It can also be implemented in the hydraulic cylinder formed in the above. In this structure, the connecting oil passage 28 is provided in the head side oil chamber 18
And the head side port 20 are connected to each other,
When the piston 12 moves to the cylinder end on the side of the head cover 16 and the cushion plunger 23 is fitted into the cushion chamber 22, when the connecting oil passage 28 is closed, the oil discharged from the head-side oil chamber 18 is cushioned. It is discharged to the head-side port 20 while being squeezed through a gap S formed between the plunger 23 and the cushion chamber 22 (the gap S corresponds to the cushion oil passage of the present invention), and a connecting oil passage. When the valve 24 is open, it is configured to be discharged without being throttled through the connecting oil passage 24. Therefore, the valve of the second embodiment also
The same operational effect as that of the first embodiment is obtained.

Further, it can be configured as in the third embodiment shown in FIG. That is, when the piston 12 moves to the cylinder end on the side of the head cover 16, the cushion plunger 23 moves the cushion chamber 2
2 is configured so as to fit tightly into the cushion chamber 22 and the oil in the cushion chamber 22 is
The head-side port 20 and the head-side port 20 are set to be discharged to the head-side port 20 through the connecting oil passage 29. In the connecting oil passage 29, a switching valve 30 capable of switching between a throttled state and an open state. Is provided. Thus, the switching valve 3
When 0 is in the throttled state, the oil in the cushion chamber 22 is discharged in a throttled state, and when the switching valve 30 is in the open state, it is discharged without being throttled. The same effect as that of the form is obtained.

Further, in the first, second, and third embodiments, the switching operation of the on-off valve 25 or the switching valve 30 is of an electromagnetic type, but is of a manual type or a pilot type. Also good. Furthermore, the cushion oil passage may be provided not only on the head side as in the above-described embodiments but also on the rod side or on both sides of the head and the rod. In addition, in the second and third embodiments, the same components (the same components) as those in the first embodiment are designated by the same reference numerals.

[Brief description of the drawings]

FIG. 1 is a perspective view of a hydraulic shovel.

FIG. 2 is a schematic view of a hydraulic cylinder showing the first embodiment.

FIG. 3 is a schematic view of a hydraulic cylinder showing a second embodiment.

FIG. 4 is a schematic view of a hydraulic cylinder showing a third embodiment.

FIG. 5 is a schematic view of a hydraulic cylinder showing a conventional example.

[Explanation of symbols]

 10 Hydraulic Cylinder 11 Cylinder Cylinder 12 Piston 18 Head Side Oil Chamber 20 Head Side Port 22 Cushion Chamber 23 Cushion Plunger 24 Connection Oil Path 25 Open / Close Valve 28 Connection Oil Path 29 Connection Oil Path 30 Switching Valve

Claims (3)

[Claims] 1. A piston, which is movably fitted in a cylinder cylinder, moves to an end of the cylinder cylinder. As a result, the discharge oil from the moving end side oil chamber is throttled to suppress the moving speed of the piston. A hydraulic cylinder provided with a cushion oil passage, wherein the hydraulic cylinder is provided with a connecting oil passage that connects the moving end side oil chamber and the drain oil passage so as to open and close so as to bypass the cushion oil passage. Hydraulic cylinder. 2. As the piston movably fitted into the cylinder cylinder moves to the end of the cylinder cylinder, the discharge speed of the piston is suppressed by squeezing the oil discharged from the moving end side oil chamber. A hydraulic cylinder provided with a cushion oil passage, wherein the hydraulic cylinder is provided with opening means for opening the throttle of the cushion oil passage. 3. The hydraulic cylinder according to claim 1, wherein the hydraulic cylinder is a bucket cylinder provided in a construction machine.