JPH0536140Y2 - - Google Patents

Description

[Detailed explanation of the idea]

[Industrial Application Field] The present invention relates to a rod packing used, for example, in reciprocating pumps, hydraulic cylinders, plunger type hydraulic motors, and the like. [Prior Art] FIGS. 6 and 7 are cross-sectional views of conventional rod packings used in reciprocating pumps. In the figure, a spacer 6, a packing 5, and a packing 3 are fitted to the reciprocating rod 1 as shown in the figure.
It is housed in the retainer 2. The packing 3 is divided into 3 to 5 pieces as shown in Fig. 6b, and is tightened with a garter spring 4, and the rod 1 is tightened with a garter spring 4.
The inner peripheral surface is in contact with. The rod 1 reciprocates in the directions of arrows X and Y to pressurize the fluid, and in FIG. 6a, the P section is on the high pressure side and the Q section is on the atmospheric side. When rod 1 moves in the direction of arrow X, it is in the discharge stroke and P
High pressure is generated in the area. Further, when moving in the direction of the arrow Y, the suction stroke occurs, and the P portion has a low suction pressure. The packing 3 and the packing 5 are made of a plastic sliding material, and the spacer 6 is made of a metal material. A large gap is provided between the rod 1 and the retainer 2 to prevent contact, but the gap between the spacer 6 and the rod 1 is made small so that even if high fluid pressure is applied to the seal 5, the gap will not be removed. This prevents Patsukin 5 from protruding. The outer peripheral side of the spare 6 is free and can move in the radial direction, and even if it comes into contact with the rod 1, it will be in a concentric state with respect to it. When the rod 1 moves in the direction of the arrow X and the pressure in the P section becomes high, this high pressure fluid acts on the packings 3 and 5 and the outer periphery of the spacer 6 inside the retainer 2. Since the spacer 6 is made of a metal material, its Young's modulus is large and the amount of deformation due to the pressure of the fluid is small, but the packing 5 and the packing 3 are made of plastic and have a small Young's modulus, so the amount of deformation is large. Although the packing 5 is previously provided with a gap relative to the rod 1, the deformation caused by the high-pressure fluid brings it into pressure contact with the rod 1, so that the gap is almost eliminated and leakage of the high-pressure fluid is prevented. On the other hand, since the gasket 3 is divided, there is some leakage when the pressure is high, and the gasket 5 is responsible for sealing the high-pressure fluid. However, when rod 1 is moving in the direction of arrow Y, the pressure at section P is low;
Since the external pressure acting on the packing 5 is low, the amount of deformation is also small, and since there is a gap between the packing 5 and the rod 1, the sealing effect is small. At this time, the gap between the rod 1 and the seal 3 is reduced by the force of the garter spring 4 and the low fluid pressure, thereby keeping leakage to a minimum. In this way, in the rod packing, the split-type packing 3 takes care of leakage when low pressure is applied, and the integral packing 5 takes care of leakage when high pressure is applied. The spacer 6 serves to prevent the gasket 5 from protruding when high pressure is applied. [Problems to be solved by the invention] In the conventional rod packing as described above, the ratio of the outer diameter to the inner diameter of the packing 5 is large and the rigidity appears to be large at first glance, but the Young's modulus of the material is low. When a high external pressure acts on the rod 1, the fluid pressure in the gap with the rod 1 is reduced due to the throttling effect in the gap, as shown in FIG. 7a. Therefore, the differential pressure on the spacer 6 side is large in the packing 5, and the packing 5 is deformed into the shape shown in FIG. 7b. At this time, rod 1 is moving in the direction of arrow X, so
The gap between the packing 5 and the rod 1 is shaped such that the gap becomes larger in the direction in which the rod 1 moves.
In other words, it becomes a divergent gap. Since it is difficult for an oil film of lubricating oil to form in a gap of such a shape, no hydrodynamic film pressure is generated, and the external pressure applied to the packing 5 is partly supported as internal stress of the packing material, but most of it is supported by internal stress of the packing material. This results in a contact friction force between the rod 1 and the seal 5, causing problems such as wear of the seal 5 or, in the worst case, seizure of the seal 5. [Means for Solving the Problems] The rod packing according to the present invention is intended to solve the above problems, and includes a retainer on the low pressure side and an annular packing located on the high pressure side and fitted to the rod. It is characterized by a structure in which an annular metal spacer having a notch provided on the side in contact with the retainer or in the vicinity of the upper rod inside is fitted between the retainer and the retainer.

[Effect]

That is, in the rod packing according to the present invention, the annular metal spacer is formed to become thinner near the rod, and is spaced between the retainer on the low pressure side and the annular packing located on the high pressure side and fitted on the rod. Since the rod is fitted, even if the rod moves in the direction of the discharge stroke and high pressure in the axial direction is applied to the spacer, the spacer is made of metal and has rigidity, so it will not deform and the gap between the spacer and rod will be reduced. It is displaced along with the packing so that it becomes wedge-shaped, becoming smaller in the direction of the rod's movement. When the gap between the packing and the rod has such a shape, an oil film of lubricating oil is easily formed in this gap, and the sliding friction force between the packing and the rod is reduced by the hydrodynamic film pressure.

【Example】

1 and 2 are explanatory diagrams of a rod packing according to the first embodiment of the present invention, and FIGS. 3 to 5 are explanatory diagrams of rod packing according to the second to fourth embodiments of the present invention, respectively. be. Note that common members in FIGS. 6 and 7 are given the same reference numerals.
That is, in FIGS. 1 and 2, in the rod packing according to the first embodiment, a spacer 16, a packing 5, and a packing 3 are respectively fitted to a reciprocating rod 1 and housed in a retainer 2, as in the conventional example. ing. The packing 3 is divided into 3 to 5 pieces, tightened by a garter spring 4, and fitted into the rod 1 with its inner peripheral surface in contact with the rod 1. Rod 1 reciprocates in the directions of arrows X and Y to pressurize the fluid.
The P section is on the high pressure side and the Q section is on the atmospheric side. When the rod 1 moves in the direction of the arrow X, high pressure is generated in the P section during the discharge stroke. Further, when moving in the direction of the arrow Y, the suction stroke occurs, and the P portion has a low suction pressure.
The packing 3 and the packing 5 are made of a plastic sliding material, and the spacer 16 is made of a metal material. A large gap is provided between the rod 1 and the retainer 2 to prevent contact, but the gap between the spacer 16 and the rod 1 is made small so that even if high fluid pressure is applied to the packing 5, the gap will not be removed. This prevents Patsukin 5 from protruding. The outer peripheral side of the spacer 16 is free and can move in the radial direction, and even if it comes into contact with the rod 1, it is concentric with it. When the rod 1 moves in the direction of arrow X and the pressure in the P section becomes high, this high pressure fluid acts on the packings 3 and 5 and the outer periphery of the spacer 16 inside the retainer 2. Since the spacer 16 is made of a metal material, its Young's modulus is large and the amount of deformation due to the pressure of the fluid is small. However, the packing 5 and the packing 3 are made of plastic and have a small Young's modulus, so that the amount of deformation is large. The packing 5 is previously provided with a gap with respect to the rod 1, but due to the deformation caused by the high-pressure fluid, the packing 5 is brought into pressure contact with the rod 1, so that the gap is almost eliminated, and leakage of the high-pressure fluid is prevented. On the other hand, Patsukin 3
Since it is divided, there is some leakage when the pressure is high, and the sealing of the high pressure fluid is mainly done by the gasket 5. However, when rod 1 is moving in the direction of arrow Y, the pressure at section P is low and the external pressure acting on packing 5 is also low, so the amount of deformation is small, and there is a gap between rod 1 and sealing effect. small. At this time, the packing 3 is deformed by the pressing force of the garter spring 4 and the low fluid pressure, and the gap between the rod 1 and the packing 3 is reduced to keep leakage to a minimum. In this way, in this rod packing, the split packing 3 takes care of leakage when low pressure is applied, and the integral packing 5 takes care of leakage when high pressure is applied. The spacer 16 serves to prevent the gasket 5 from protruding when high pressure is applied. Furthermore, this rod packing has a notch 1 on the retainer 2 side of the spacer 16 as shown in FIG.
6' is provided. When the rod 1 moves in the direction of the arrow X, the pressure in the P section becomes high, and the axial pressure acting on the packing 5 acts directly on the spacer 16. When the pressure increases, the spacer 16 is rigid, so it is displaced as shown in FIG. 2, and the packing 5 is also displaced, but together they form a wedge-shaped gap with the rod 1. When rod 1 moves in the direction of arrow The contact friction force between the packing 5 and the rod 1 can be reduced by the hydrodynamic film pressure. Therefore, Patsukin 5
Alternatively, wear on the rod 1 is significantly reduced. In addition, a tapered notch 26' may be provided in the spacer 26 as shown in FIG. 3, or a protrusion 36' may be provided on the outer circumferential side of the spacer 36 as shown in FIG. The effects of this can be obtained.
Furthermore, similar effects can be obtained by forming a groove 46' on the inner peripheral side of the spacer 46 as shown in FIG.

[Effect of the idea]

Since the rod packing according to the present invention is constructed as described above, even if the rod moves in the direction of the discharge stroke and a large contact friction force is applied between the packing and the rod, the packing is also displaced due to the displacement of the spacer. However, a wedge-shaped gap is formed between the packing and the rod, which becomes smaller in the direction of the rod's movement, and an oil film of lubricating oil is formed in this gap, and this hydrodynamic film pressure reduces the contact friction between the packing and the rod. Since the force is reduced, wear and seizure of the packing and rod can be prevented.

[Brief explanation of the drawing]

1 and 2 are sectional views of the rod packing according to the first embodiment of the present invention, and FIGS. 3 to 5 are sectional views of the rod packing according to the second to fourth embodiments of the present invention, respectively. FIGS. 6 and 7 are cross-sectional views of conventional rod packings. 1... Rod, 2... Retainer, 3, 5... Packing, 6, 16, 26, 36, 46... Spacer.

Claims (1)

[Scope of utility model registration request] An annular metal spacer with a notch provided near the rod on the side in contact with the retainer or inside the retainer is fitted between the retainer on the low pressure side and the annular packing located on the high pressure side and fitted on the rod. Rodsudpatzkin is characterized by the fact that it becomes.