RU2265752C2 - Piston pump assembly plunger - Google Patents

Abstract

FIELD: hydraulic machines; oil producing industry.

SUBSTANCE: invention can be used in piston hydraulic machines, such as oil-well sucker-rod pumps, compressors, etc. Assembly plunger of piston pump has body with fitted-on set of alternating sealing pliable and rigid rings mounted through elastically pliable bushing, and device for pressing said set of rings in axial direction. End faces of rings are provided with mating surface. Sealing pliable rings have trapezoidal cross section, wider base being pointed outwards. Rigid rings have trapezoidal cross section with wider base pointed to side of elastically pliable bushing. Sealing pliable rings can be made of fluoroplastic, and spacer rings, of steel or cast iron or bronze. Set sealing rings can be divided into two sections with separating bushing placed in between. Said bushing has inner space connected through channels with high-pressure space of plunger. Separating bushing is made of pliable material, for instance, of fluoroplastic, or made elastically pliable in axial direction, for instance, in form of spring. Plunger is provided with valve with shutoff element with travel stop in which insert made of polymeric material, for instance, of fluoroplastic, is installed.

EFFECT: improved efficiency of sealing, reliability and manufacturability of plunger.

6 cl, 5 dwg

Description

The invention relates to the field of hydraulic engineering and can be used in such reciprocating hydraulic machines as well piston rod piston pumps used in oil production, compressors, etc.

A known plunger piston pump plunger comprising a housing, a set of rigid sealing rings of rectangular cross section, mounted on the housing eccentrically through an elastic ductile sleeve and touching one another at flat ends, a device for compressing a set of rings in the axial direction and a valve (see RU 2037077, IPC F 16 J 15/26, 06/09/1995).

However, the known design of the prefabricated plunger has insufficient sealing efficiency, reliability and manufacturability.

The lack of sealing efficiency lies in the fact that the contact of each of the sealing rings eccentrically set against the mirror of the cylinder is realized along a small arc, and the entire set of rings along a certain helical line due to the angular displacement of the eccentricity of the rings during assembly. Therefore, with the entire working surface of the plunger, there is a sealing screw protrusion and a helical groove through which leaks occur. In addition, touching the rings along a narrow area of the cylinder mirror causes a decrease in the reliability of the pump, as it can lead to uneven wear on the working surface of the cylinder, to vibration during operation and jamming of the plunger.

The lack of manufacturability of the known plunger is due to the fact that it is very difficult to regulate the friction force at the ends of the rings during their radial movement, which makes it difficult to enter the plunger into the cylinder when assembling the pump. Another disadvantage is the difficulty in selecting a plunger-cylinder pair, in other words, in order to provide the required landing group for the specified pair, it is necessary for each cylinder size to produce an individual set of rings only for this particular cylinder.

The closest analogue of the proposed prefabricated plunger can be considered the plunger disclosed in patent RU No. 2076953 C 1, IPC 7 F 04 B 53/02, 04/10/1997, which uses a seal in the form of a set of alternating sealing and spacer rings. Such a plunger is devoid of the above disadvantages, however, the placement of a set of rings directly on the housing (tubular bearing rod) does not allow self-centering of the set of rings relative to the base surfaces, which reduces manufacturability and complicates the assembly of the plunger.

In addition, the lack of operation of the commonly used saddle - locking element pair (for example, a ball) in the valve of the plunger is caused by the impact interaction of the locking element with a rigid metal travel stop each time the valve is opened. Such cyclic impact interaction can cause fretting corrosion on the working surfaces of contacting metal parts as they work. Ultimately, fretting corrosion resulting from damage to the working surfaces can significantly reduce the sealing efficiency of the saddle - locking element pair.

The objective of the invention is to increase the efficiency of the seal, reliability and manufacturability of the plunger piston pump assembly.

The problem is solved due to the fact that in the assembly piston of the piston pump containing the housing mounted on it with the possibility of axial displacement, a set of alternating sealing flexible and rigid rings, the ends of which have a mating surface, as well as means for compressing the said set of rings in the axial direction, a set of o-rings is mounted on the housing through an elastomeric sleeve, while the o-rings have a trapezoidal cross section, and the wide base of the trapezoid is malleable to the ring is facing outward, and the rigid rings are toward the elastically flexible sleeve. The malleable o-rings may be made of malleable material or split of hard material, and the rigid rings of hard material. The set of o-rings can be divided into two sections, between which a dividing sleeve is installed with an internal cavity connected by channels to the high-pressure cavity of the plunger. The separation sleeve is made of ductile material, for example fluoroplastic, or is made elastic in the axial direction, for example in the form of a spring. The plunger contains a valve having a locking element with a stroke limiter, in which an insert is made of a polymer material, for example, fluoroplastic.

The invention is illustrated by drawings, where figure 1 shows the construction of a prefabricated piston of a piston pump, a longitudinal section; figure 2 - element I in figure 1; figure 3 - element II in figure 1; figure 4 - prefabricated plunger with a set of sealing and spacer rings, separated by a sleeve; figure 5 - prefabricated plunger with a set of o-rings, divided into two sections elastically flexible in the axial direction of the sleeve, made in the form of a spring.

The pre-assembled piston pump plunger (Figs. 1, 2, and 3) consists of a housing 1, on which is installed, through, for example, rubber, an elastic-flexible coaxial sleeve 2, a set of o-rings 3 and 4 rings — flexible and rigid, respectively. These rings are made of a trapezoidal cross section, are installed in the set alternately and so that the larger base of the trapezoid of the cross section of the flexible sealing rings 3 is facing outward, i.e. It is located on the mirror side of the cylinder, and the rigid sealing rings 4 on the side of the elastically flexible sleeve 2. The sealing rings 3 can be made of ductile material, for example fluoroplastic. In addition, the flexibility of these rings can also be ensured by the fact that they can be made split of hard material, for example, steel, cast iron, bronze, etc. (not shown in the drawing). Hard rings 4 are made of the same hard material.

A set of rings 3 and 4 is located between the two pressure rings 5, which together with the pressure nut 6 form a means for compressing the ring set, which ensures their necessary axial compression.

On the body 1 of the plunger a valve is installed, consisting of a valve body 7, a sealing pair of a seat 8 - a locking element 9 (for example, a ball) and a fitting 10. In the travel stop 11 of the locking element, made in the form of a partition in the valve body 7, an insert 12 is installed, made of a polymeric material, for example, fluoroplastic in the form of a threaded pin (see figure 1 and figure 3). The stroke limiter can also be made in the form of a pin pressed into the valve body perpendicular to its axis with a polymer sleeve worn on it (not shown in the drawing).

The set of o-rings 3 and 4 can be divided into two sections in the assembly plunger (Fig. 4), between which a separation sleeve 13 is installed, the inner cavity of which is connected to the high-pressure cavity of the plunger by channels 14 and 15, made in the housing 1 and the intermediate sleeve 16 respectively. The separation sleeve 13 is flexible, for example, of a flexible polymer material such as fluoroplastic or polyamide.

Another design of the separation sleeve is shown in figure 5, which shows the separation sleeve 17, made elastically flexible in the axial direction, for example in the form of a steel spring. The spring properties of the sleeve in this case provide milled grooves in the circumferential direction, for example, staggered (see grooves 18 in FIG. 5). Before assembly, the sealing rings 3 and 4 of the plunger are performed on the outer diameter with a tolerance that ensures the free placement of the plunger in the cylinder.

When assembling the plunger with the pump, the push nut 6 (see Fig. 1) is tightened “by hand”, the plunger is freely inserted into the pump cylinder. Then, the pressure nut 6 is tightened with a wrench so that compliant O-rings 3, by squeezing them in the radial direction by rigid O-rings 4 (see Fig. 2), form a minimum clearance or clearance-free fit with the cylinder mirror, which increases manufacturability and simplifies assembly. In this case, the resilient sleeve 2 provides self-alignment - centering the set of sealing and spacer rings 3 and 4 relative to the base centering surfaces.

During the operation of the assembly plunger as part of the pump, the malleable sealing rings 3 under conditions of tight fit in the first hours of running-in wear out slightly, while the wear particles of the antifriction material of the fluoroplastic type are deposited on the surface of adjacent rigid o-rings, which were installed during assembly of the pump with such a gap that would provide fairly loose setting of the plunger in the cylinder. Thus, the working surface of the spacer rings is covered with a thin antifriction film. This reduces the gaps on the rigid sealing rings and eliminates seizure and seizure of friction surfaces, thereby increasing the reliability of the pump and reducing leakage.

When the prefabricated plunger is operated with a separating flexible sleeve 13 (see Fig. 4), at each suction cycle, its working surface is pressed against the cylinder mirror by the pressure of the medium flowing through the channels 14 and 15 into the internal cavity of the sleeve 13 from the high pressure cavity of the plunger, which significantly reduces leaks in the pump. If instead of the sleeve 13, an axially resilient dividing sleeve 17 is installed (see FIG. 5), the effect of reducing leaks during pump operation is ensured by the fact that the wear of the malleable sealing rings 3 is compensated by their extrusion in the radial direction due to the constant axial pressure produced by the spring spacer sleeve 17.

Improving the reliability of the sealing pair of the saddle 8 - the locking element 9 (see figure 1 and 3) is achieved by the fact that during the operation of the pump, the locking element 9 interacts with the stroke limiter 11 through the polymer insert 12, which eliminates fretting corrosion of the contacting surfaces and at the same time dampens impact interaction of elements.

Claims (6)

1. An assembly piston of a piston pump, comprising a housing mounted axially displaceable thereon, a set of alternating sealing flexible and rigid rings, the ends of which have a mating surface, as well as means for compressing said set of rings in the axial direction, characterized in that the set of sealing rings mounted on the housing through an elastomeric sleeve, while the malleable and rigid rings have a trapezoidal cross section, with a wide base of the trapezoid of the malleable rings facing outward, and the rigid rings toward the resilient sleeve. 2. The prefabricated plunger according to claim 1, characterized in that the malleable sealing rings are made of malleable material or split from hard material, and the rigid sealing rings are made of hard material. 3. The prefabricated plunger according to claim 1, characterized in that the set of o-rings is divided into two sections, between which a separation sleeve is installed with an internal cavity connected by channels to the high pressure cavity of the plunger. 4. The prefabricated plunger according to claim 3, characterized in that the separation sleeve is made of ductile material. 5. Assembled plunger according to claim 3, characterized in that the separation sleeve is made elastically flexible in the axial direction, for example, in the form of a spring. 6. Prefabricated plunger according to claim 1, characterized in that the plunger contains a valve having a locking element with a stroke limiter, in which a part made of a polymeric material is installed.

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