RU218359U1 - FUEL PUMP HIGH PRESSURE - Google Patents

Abstract

The utility model relates to diesel engine building, namely to high-pressure fuel pumps for common rail engine fuel systems. The high-pressure fuel pump includes a housing 1, at least one plunger sleeve with an injection valve 3 installed in it, and a sealing ring installed in the housing bore. It additionally contains a composite sealing ring 4, made in the form of a combination of two round rings of rectangular cross section, of which the inner ring is made of an elastic elastic material, and the outer ring is made of a thermoplastic. The outer ring is connected to the inner ring by a transitional fit and is installed in a bore in the pump housing in the zone of communication of the high-pressure channels by a transitional fit. The inner ring of the compound sealing ring may be made of fluorosilicone rubber, and the outer ring of the compound sealing ring may be made of polyetheretherketone.

Description

The utility model relates to diesel engine building, namely to high-pressure fuel pumps of common rail fuel systems (hereinafter referred to as high-pressure fuel pumps).

In practice, the problem often arises of sealing high-pressure hydraulic circuits.

Patent RU 88096 discloses the design of a detachable joint, where a composite sealing ring is used, the outer part of which is made of polyamide materials, for example, caprolon, and the inner part is made of steel, and the parts of the ring are installed coaxially to each other with an interference fit (US Pat. RU 88096, 27.10 .2009. Bull. No. 30). According to a well-known solution, the inner part of the composite sealing ring has a stiffening rib in cross section and is provided with annular elastic lips and conical sealing surfaces. Limiting the deformation of the outer part of the composite sealing ring is provided by using a special part - a stop, with the inner surface of which the stiffener of the composite sealing ring is mated in a sliding fit.

The disadvantages of the known solutions include the presence of a stiffener, which is an annular protrusion on the outer surface of the composite sealing ring, which is easily damaged both before and during installation. In this case, it will be difficult and, in some cases, impossible to ensure a sliding fit of the composite sealing ring in the abutment. In addition, the disadvantages of the known solution include the use of an additional element for sealing - a stop, which must be made with an accuracy sufficient to ensure, firstly, a sliding fit on a composite sealing ring and, secondly, the necessary pressing force of the conical surfaces in the nipples to the tapered sealing surfaces of the composite sealing ring.

Author's certificate SU 1810689 discloses the design of a Gamayunov composite sealing ring containing an O-ring and two L-shaped metal washers covering its outer surfaces (Ed. St. SU 1810689, 23.04.1993. Bull. No. 15). According to a well-known solution, a recess is made on the outer side of the O-ring for installing metal washers. Said washers have slots and are installed in the gasket symmetrically with respect to the middle plane of the recess.

The disadvantages of the known solution include the complexity of the design, which complicates the technology for manufacturing a composite sealing ring: the mold for the gasket must have an appropriate protrusion, and for the manufacture of metal washers, obviously, two dies are required - punching and bending, or a combination of two stamping operations in one die , which also presents certain difficulties.

Patent DE 102014225794 discloses the design of the injection pump, including a housing, a plunger sleeve, called the cylinder head by the authors of the well-known solution, a discharge valve and a joint seal between the pump housing and the plunger sleeve (US Pat. DE 102014225, 06/16/2016). The plunger sleeve (“cylinder head”) and the pump housing are mated along flat surfaces adjacent to each other during assembly. An annular groove is made on the mating plane of the pump housing, where, during assembly, a joint seal is installed between the pump housing and the plunger bushing. Joint sealing is made in the form of an o-ring.

The disadvantages of the known solution include the risk of leakage at the junction of the pump housing and the plunger bushing, since it is known that for fluid pressures over 20 MPa, it is recommended to install protective washers together with O-rings (Seals and sealing technology: Handbook / L.A. Kondakov, A I. Golubev, V. B. Ovander, etc.; Under the general editorship of A. I. Golubev, L. A. Kondakov. - M: Mashinostroyeniye, 1986. - 464 pp. P. 127). It is known that protective washers are installed in addition to the elastic sealing rings as separate parts. From the illustration to the well-known solution, it can be seen that the O-rings are installed without protective washers.

The closest, according to the totality of essential features - the prototype of the claimed utility model - is a sealing assembly, including a sealing ring and covering it from the outside and a rectangular ring connected to it (US Pat. DE 8513179, 25.07.1985). According to the known solution, the outer ring has an annular protrusion on the inner diameter, designed to accommodate the inner ring. The height of the outer ring is close to the height of the inner ring, so that during assembly the inner ring is deformed to the height of the outer ring.

The disadvantages of the known solution include the need to perform an annular protrusion on the inner diameter of the outer ring, which complicates the manufacturing technology.

The technical problem, which the proposed utility model is aimed at, is the creation of a high-pressure fuel pump design that has a manufacturable and reliable seal at the junction between the pump housing and the plunger bushing.

The technical result of the implementation of the proposed utility model is the simplification of the design of the seal at the intersection of the high-pressure channels passing in the pump housing and in the plunger bushing.

The problem is solved by using to seal the joint between the pump housing and the plunger bushing in the area of the high-pressure channels of a composite sealing ring, the inner part of which is made of elastomer, the outer part is made of thermoplastic, both parts form an interference connection.

A novelty in the high-pressure fuel pump proposed as this utility model is the use of a composite sealing ring to seal the joint between the pump casing and the plunger bushing in the area of the high-pressure channels, the inner part of which is made of elastomer, the outer part is made of thermoplastic, both parts form a connection along the transition landing.

This feature is new, significant, industrially feasible and is aimed at solving the technical problem set by the utility model.

According to the utility model, a high-pressure fuel pump of the Common Rail system is proposed, including a housing, at least one plunger bushing with an injection valve installed in it, and a sealing ring installed in the housing bore. The pump additionally contains a composite sealing ring made in the form of a combination of two rings, round in plan, of rectangular cross section, of which the inner ring is made of an elastic elastic material, and the outer ring is made of thermoplastic, the outer ring is connected to the inner ring by a transitional fit and is installed in boring in the pump housing in the zone of communication of the high-pressure channels along the transition fit.

The inner ring of the compound sealing ring is made of fluorosilicone rubber, and the outer ring of the compound sealing ring is made of PEEK.

The design of the injection pump, proposed in accordance with the claimed utility model, is illustrated by drawings (Fig. 1-3). The drawings indicate:

1 - pump casing;

11 - high pressure channel;

2 - plunger bushing;

21 - high pressure channel;

3 - discharge valve;

4 - composite sealing ring;

41 - the inner ring of the composite sealing ring;

42 - the outer ring of the composite sealing ring;

5 - sealing ring;

6 - fitting;

7 - plug.

In FIG. 1 shows a section of the injection pump, illustrating the removal of fuel after the delivery valve 3 through the fitting 5.

A plunger sleeve 2 is installed in the pump housing 1. Sleeve 2 of the plunger together with the plunger (not marked in the figure) forms a unit, which in the literature and in practice is sometimes called the pump section.

A discharge valve 3 is installed in the sleeve 2 of the plunger. The number of discharge valves 3 corresponds to the number of pump sections, which, in turn, is determined by the design features of a particular pump.

The figure shows, by way of example, not excluding other embodiments, a pressure valve 3 of a ball type. After the delivery valve 3, depending on the design features of the injection pump, a fitting 5 or a plug 6 can be installed. of the pumping sections is supplied to the fitting 5 through the communicating high-pressure channels 11 and 21, made after the injection valve 3, depending on the fuel flow during the injection process, in the pump housing and plunger bushings, respectively. A variant of the pump section without fitting 5 is shown in Fig. 2.

On the mating plane of the pump housing 1, a bore is made to install the seal 5.

In the exit zone of the high-pressure channel 11 to the mating plane in the pump housing 1, a bore is made where a composite sealing ring 4 is installed. The composite sealing ring 4 is made in the form of two rings installed one into the other along a transitional fit. The inner ring 41 is made of elastic elastic material.

It is preferred that the inner ring 41 be made of fluorosilicone rubbers.

The outer ring 42 is made of a thermoplastic polymer.

It is preferred that the outer ring 42 be made of polyetheretherketone.

Both rings - 41 and 42 - have a rectangular cross section.

The height of the outer ring 42 is close to the height of the inner ring 41. After assembly, the plunger sleeve 2 deforms both rings - 41 and 42 - with varying degrees of deformation, being attracted to the pump housing 1 until it comes into contact with its mating plane.

The high-pressure fuel pump of the Common Rail system, offered as the present utility model, operates as follows.

In the process of injection, the fuel opens the discharge valve 3. If the high-pressure fuel pump has pump sections with plugs 6 installed, the fuel after the injection valves 3 in these sections through channels 21 and 11 enters the pump section with a fitting 5. Through channel 21 in the sleeve 2 of the plunger of the pump section with fitting 5 installed, fuel flows to fitting 5. In the pump section, where there is fitting 5, the fuel after the delivery valve 3 immediately flows to fitting 5. The direction of fuel movement in Fig. shown by arrow.

Due to the presence of a composite sealing ring 4, the tightness of the joint between the pump housing 1 and the plunger sleeve 2 in the communication zone of the high pressure channels 11 and 21 is ensured.

An example of the implementation of the utility model.

An experimental radial-plunger injection pump with three pump sections was manufactured. The outlet fitting was installed on only one section, plugs were installed on the other two. The inner ring of the compound sealing ring was made of fluorosilicone rubber, the outer ring of the compound sealing ring was made of polyetheretherketone. The maximum fuel pressure in the tests was 2150 kg/cm ² . The leak was not found.

The proposed design of the high-pressure fuel pump is being prepared for implementation at the Altai Precision Products Plant.

Claims (3)

1. A high-pressure fuel pump, including a housing, at least one plunger sleeve with a discharge valve installed in it, and a sealing ring installed in the bore of the housing, characterized in that it additionally contains a composite sealing ring made in the form of a combination of two round in terms of rings of rectangular cross section, of which the inner ring is made of resilient elastic material, and the outer ring is made of thermoplastic, and the outer ring is connected to the inner ring by a transitional fit and is installed in a bore in the pump housing in the zone of high-pressure channels communication by a transitional fit. 2. High pressure fuel pump according to claim 1, characterized in that the inner ring of the compound sealing ring is made of fluorosilicone rubber. 3. High pressure fuel pump according to claim. 1, characterized in that the outer ring of the composite sealing ring is made of polyetheretherketone.

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