JPS5910445Y2 - Sealing device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a seal device that is attached to a piston rod that is subjected to shock vibrations in a hydraulic cylinder of a hydraulic excavator, etc., in order to prevent dust from entering and oil leakage.

A sealing device in a current hydraulic cylinder will be explained with reference to FIGS. 1 to 3.

As shown in FIG. 1, a cylinder 1, a cylinder bottom 2, and a cylinder head 3 constitute a pressure vessel, and a piston rod 5 integrated with a piston 4 slidably passes through the cylinder head 3. An O-ring 6 and a wear ring 7 attached to the outer circumference serve as a seal for pressure oil when the piston 4 slides on the inner circumferential surface of the cylinder 1, and also provide a bearing function.

On the other hand, on the sliding surface between the cylinder head 3 and the piston rod 5 passing through it, a pusher 8, a buffer ring 9, a U packing 10, and a dust seal 11 are installed in grooves provided in the cylinder head 3, respectively. It has a sealing function for pressure oil from a hydraulic chamber 15 formed on the right side of the piston 4 and a bearing function when the rod slides.

The cylinder 1 is provided with an oil inlet 12 that opens close to the cylinder bottom 2 side and an oil discharge port 13 that opens close to the cylinder head 3 side. They communicate with partitioned hydraulic chambers 14 and 15, respectively.

Therefore, when pressure oil is supplied into one hydraulic chamber 14 from the inlet 12, the piston 4 and its rod 5 are driven to the right, and at the same time, the pressure oil in the other hydraulic chamber 15 is supplied to the outlet 1.
3 is discharged to the outside.

The dust seal 11 has a lip 19 on the sliding surface side of the piston rod 5 to prevent dust from entering from the outside and oil from leaking from the inside.

Further, the outer periphery of the dust seal 11 is reinforced with a metal ring 20 having an L-shaped cross section.

Figure 2 is a schematic diagram of the hydraulic cylinder shown in Figure 1.
On one side, a pin bearing 16 (
There is also an integrated pin bearing 17 at the tip of the other piston rod 5, which is connected to another device (not shown) to be driven.

Figure 3 shows the assumption that when the hydraulic cylinder in Figure 2 is driven, the load and vibration on the driven side connected by pin bearings 16 and 17 act as a column with an equal cross-sectional structure between pin bearings 16 and 17. At this time, the piston rod 5 vibrates in the direction of the arrow A as shown by the solid line and the dashed line at ΔH shown by 18 in the vicinity of the cylinder head 3, and the piston rod 5 in operation in this state slides. In the mounting structure of the dust seal 11 having the general structure shown in Figure A), the lip 19 floats up from the sliding surface of the piston rod 5, creating a space, allowing dust to enter the inside from the outside, and causing oil to leak from the inside to the outside. .

When dust enters, U packing 10, Batsu Fanong 9,
This will damage the pusher 8, which will eventually result in a loss of sealing and bearing function.

Furthermore, if oil leaks outside, the machine becomes dirty and oil is wasted.

In other words, the currently used dust seal 11 does not fully demonstrate its function, and even though good results were obtained in static tests,
Dynamically, the lip 19 cannot follow the sliding surface of the piston rod 5, causing the above-mentioned problems.

The purpose of this invention is to eliminate the drawbacks of general seal devices, including dust seals, which occur because the seal device separates from the piston rod due to vibrations when the piston rod slides. The member is installed in the cylinder head via an elastic member, and even if the member vibrates in the direction perpendicular to the axis while the piston rod is sliding, the seal member follows the piston rod integrally, thereby preventing the seal member from separating from the piston rod. It is used in hydraulic cylinders of hydraulic excavators, etc., as well as in general equipment where the piston rod vibrates.

Hereinafter, the present invention will be explained with reference to FIG. 4 and FIG. 5B.

As shown in Fig. 4, 10 is a U packing, and a metal ring 2
The dust seal 11 with 0 is attached to the cylinder head 3 of the cylinder 1.
There is an O-long groove 40 between the cylinder head 3 and the dust seal 11, into which an O-ring 41 is attached with a moderate surface pressure. ) and the inner peripheral surface of the fitting groove of the cylinder head 3, there is a gap 46 of Δd.

In other words, the lip 19 of the dust seal 11 comes into contact with the piston rod 5 with an appropriate surface pressure due to the appropriate surface pressure from the O-ring installed in the O-ring groove 40, and is able to slightly slide. The gap 46 (Δd) is formed, and in this state, oil leakage and dust intrusion between the dust seal 11 and the cylinder head 3 are sealed.

Further, a presser foot 42 is provided close to the right end surface of the metal ring 20 of the dust seal 11 to prevent the dust seal 11 from being pulled out to the outside (to the right).

The presser foot 42 fits into the side groove of the cylinder head 3 and is attached with bolts and nuts 43, and there is a small gap 45 (ΔX) between the presser foot 42 and the right end surface of the dust seal ring 20.
This allows the dust seal 11 to move as the piston rod 5 slides.

The dust seal 11 itself shown in Fig. 4 is a commercially available product, but a metal ring 2 whose outer periphery and right end are reinforced with an L-shaped steel plate
Normally, the dust seal 11 is integrally formed with a rubber or resin material that holds the lip 19, and when the dust seal 11 is installed in the groove of the cylinder head 3, it is done by a light press fit, and the dust seal 11 and Oil leakage between the cylinder heads 3 is prevented from occurring.

In addition to the above-mentioned commercial products, the dust seal 11 is also made of metal, and there is also one that does not have the ring 20 and is made entirely of rubber or resin material.

To explain the function and effect, when the piston rod 5 moves from side to side during driving, the lip 19 of the dust seal 11 will close to the O-ring 4.
Since the piston rod 5 is brought into contact with the surface of the piston rod 5 by the pressure of 1, it can be slightly moved to the right or left by the amount ΔX of the minute gap 45 due to the frictional force of the sliding surface of the rod.

Further, when the piston rod 5 is subjected to impact vibration or vibration as shown in FIG. 3, a relative displacement occurs between the piston rod 5 and the cylinder head 3, but at this time, the dust seal 11 tends to vibrate together with the piston rod 5. .

That is, as shown in FIG. 5B, there is a spring force due to the tightness between the lip 19 of the dust seal 11 and the piston rod 5, and a spring force due to the tightening of the O-ring 41 press-fitted between the outer periphery of the dust seal 11 and the cylinder head 3. Moreover, since there is a gap 46 (Δd) between the cylinder head 3 and the outer periphery of the dust seal 11, the dust seal 11 follows the vibrations of the pistons ron and 5 in the direction perpendicular to the axis. can.

In the conventional dust seal, when the piston rod 5 vibrates as shown in FIG. 5A, the lip 19 and the piston rod 5
If the piston rod 5 is spaced apart, dust will enter the inside as described above, and oil will leak from the inside to the outside. However, in the case of the present invention, the lip 19 does not separate from the vibrating surface of the piston rod 5, as shown in FIG. Because they vibrate as one, the lip 19
The dust seal function can be fully demonstrated.

The minute gap 45 (ΔX) between the presser feet on the right end surface of the dust seal metal ring 20 is 0.05 to 0.1 mm, and the gap 46 (Δd) between the outer circumference of the dust seal 11 and the inner circumference of the cylinder head 3 is Although it depends on the system pressure applied to the cylinder 1, it is about 0.1 to 1 mm.

In the above explanation, the piston rod 5 was subjected to impact vibration or vibration, but even if the cylinder 1 vibrates in the same way as above, the l-motion of the dust seal 11 with the piston rod 5 does not change as shown in FIG. 5B. .

Also, the O-ring 41 does not have to be O-ring-shaped, but the lip 19
The type is not particularly limited as long as it has a spring force that is lower than the spring force that takes into account the shape of the material forming the part and has the function of sealing oil between the cylinder head 3 and the dust seal 11.

In short, as described in the embodiments, the present invention provides the seal member 11 that contacts the piston rod 5 sliding inside the cylinder head 3, and the cylinder head 3 that faces the radial outer circumferential surface of the seal member and the same outer circumferential surface. The sealing member 11 is disposed on the cylinder head 3 via elastic members 41 which are in contact with the inner circumferential surfaces of the piston rods and are compressed in a direction orthogonal to the axis of the piston rod 5. This is a sealing device in which a gap 46 is formed between the outer circumferential surface and the opposing inner circumferential surface of the cylinder head 3.

That is, in the present invention, the sealing member 11 (for example, a dust seal) that comes into contact with the piston rod 5 sliding inside the cylinder head 3 is constantly pressed by the elastic member 41, so that when the piston rod 5 slides, the piston rod does not vibrate or impact vibration. Even if the cylinder head 3 and the seal member 11
Since a gap 46 is provided between the seal member 11 and the outer circumference of the piston rod 5, the seal member 11 always maintains a state of contact with the piston rod 5 and vibrates as one, and does not separate from the piston rod 5. In addition to preventing oil from leaking to the outside, it also prevents dust from entering from the outside, dramatically improving the sealing function.

[Brief explanation of drawings]

Fig. 1 is a vertical cross-sectional view of the l section of the cylinder to explain the sealing device in the current hydraulic cylinder, Fig. 2 is a schematic explanatory diagram of the hydraulic cylinder of Fig. 1, and Fig. 3 is the same as that of Fig. 2. A drawing for explaining the vibration of the piston rod when the hydraulic cylinder is driven, FIG. 4 is a partial vertical sectional view showing one embodiment of the present invention, and A in FIG. 5 is the conventional dust seal in FIG. 1. B is a diagram for explaining the vibration of the dust seal according to the present invention. In the figure, 1... cylinder. 3...Cylinder head. 5... Piston rod. 10...U packing. 11... Seal member with dust seal with metal ring. 41...O-ring elastic member.

Claims (1)

[Scope of utility model registration request] A sealing member that comes into contact with a piston rod sliding in the cylinder head is in contact with the radial outer circumferential surface of the sealing member and the inner circumferential surface of the cylinder head opposite to the outer circumferential surface, and is orthogonal to the axis of the piston rod. The seal member is disposed on the cylinder head via an elastic member compressed in the direction of the seal member, and a gap is formed between the radially outer peripheral surface of the seal member and the inner peripheral surface of the cylinder head opposite to the outer peripheral surface. A sealing device characterized by: