RU2629847C2 - Diesel engine atomizer sprayer - Google Patents

Abstract

FIELD: engine devices and pumps.

SUBSTANCE: atomizer sprayer has a body with conical seat and a needle positioned therein and having sealing and damping band at base of cone that contact along its entire width with seat conical surface. A throttling cone is made behind the sealing band on the needle with angle larger than angle of seat cone. The sealing and damping band of the needle is brought closer to the surface of the seat when it is fitted creating a cushioning effect by pinching fuel in a narrow slit sharply reducing motion speed of the needle before physical contact of roughness ridges of approaching surfaces.

EFFECT: increase of atomizer sprayer service life due to increased efficiency of shock load damping in conical seal by fitting the needle on the seat softly and at low speed before the contact of surface roughness ridges of conical seal surfaces, and increasing service life of conical seal and sprayer as a whole.

2 dwg

Description

The invention relates to the field of engine construction, in particular to fuel-spraying equipment of diesel engines.

Known atomizer nozzle for an internal combustion engine (RU 2175078, IPC F02M 61/10, F02M 61/10, publ. 10/20/2001), comprising a housing with a conical seat and a needle placed in it containing a throttle-locking cone with an angle large angle of the saddle, in contact with the saddle along the line of the characteristic diameter and combined along its border with a buffer element located with a damping gap relative to the surface of the saddle. The saddle is made combined in the form of two cones combined by a stepped transition, and the needle has a single throttle-locking cone in contact with the stepped transition of the saddle along a line of characteristic diameter, which limits the part of the throttle-locking cone acting as a buffer (shock-absorbing) element from the base side.

In the above technical solution, an increase in the life of a conical seal, which is destroyed by impact loads during needle landing, is supposed to be achieved by reducing the impact force in a special buffer device, which is two converging surfaces, between which, according to the authors, the fuel is trapped. Studies have shown (Kuzkin V.G., Tolmachev A.V. Reducing shock loads when landing the nozzle of the atomizer nozzle. "Efficiency of the operation of technical systems", international collection of scientific papers. Publishing house ART, Poland - Olsztyn, 1999, p.256 ... 260), the buffer effect in such shock-absorbing devices arises with extremely small approximation of surfaces. Based on the data of these studies, the dependence

fair for diesel,

where S is the rapprochement of the surfaces at which the needle’s speed is sharply braked and their soft contact is ensured;

b _n - the width of the conical contact belt, mm

So, for example, at bn = 5 mm this approach is 8.6 μm, and at b _n = 0.5 mm it is 0.3 μm. The specified invention does not provide the value of the gap S in the buffer device when landing the needle, which makes the achievement of the effect of depreciation unlikely. However, even when the required small value of the damping gap is assigned, the depreciation effect will be short-term, since even slight wear of the actual contact between the needle and the seat will inevitably lead to the closure of the surfaces of the shock-absorbing device and the loss of density of the conical seal of the atomizer, i.e. to the failure of it.

The invention solves the problem of increasing the life of the nozzle atomizer by increasing the shock absorption in the conical seal by providing a soft landing of the needle on the saddle at a low speed until the combs of the roughness of the surfaces of the conical seal come into contact.

To ensure the necessary technical result in the known atomizer nozzle, comprising a housing with a conical seat and a needle placed in it, containing a throttle cone with an angle greater than the angle of the saddle, a shock-absorbing element, it is proposed that the needle be made with a conical sealing-shock-absorbing belt with a cone angle equal to the cone angle saddles, and the width of the belt is related to the relative specific contact pressure of the needle on the saddle and the total roughness of the contacting surfaces of the sealing-shock-absorbing belt and saddles addiction:

,

,

where b _n - the width of the sealing shock-absorbing belt, mm,

- относительное удельное контактное давление иглы на седло,

- the relative specific contact pressure of the needle on the saddle,

∑Ra is the total roughness of the contacting surfaces of the sealing-shock-absorbing belt and saddle, μm,

ρ _t - design pressure to which the conical seal retains hydraulic density, kg / cm ² ,

ρ _y - specific contact sealing pressure in the conical seal, kg / cm ² .

The approximation value S of the surface of the sealing-shock-absorbing girdle with the surface of the saddle, at which the shock-absorbing effect is manifested and the needle is sharply braked, is greater than ∑Ra and is related to the width of the sealing-shock-absorbing girdle b _{n with the} dependence S = 0.82 (b _n ) ^1.46 .

The diagrams attached to the description show:

figure 1 - nozzle atomizer in the context;

figure 2 is a diagram for determining the agreed parameters of the conical seal of the proposed atomizer nozzle.

The following notation is used in the diagrams: 1 - needle; 2 - case; 3 - conical saddle; 4 - conical sealing shock-absorbing belt; 5 - conical lateral surface of the girdle; 6 - a cavity in the housing; 7 - a throttling cone; 2α is the angle of the saddle cone; 2β is the angle of the throttling cone; b _n - the width of the sealing shock-absorbing belt; d _and - the diameter of the needle; d _o - the diameter of the base of the cone of the sealing shock-absorbing belt; P _p - the tightening force of the nozzle spring; R _y - sealing force; P _T is the pressure force of the fuel on the needle.

The sprayer includes a housing 2 with a conical seat 3, a needle 1, a conical sealing and shock-absorbing girdle 4 of width b _n and a tapered side surface 5, with a cone angle equal to the cone angle of the conical seat 3. Housing 2 is made with a cavity 6, in which, after landing, the needle is received design pressure ρ _T to which the conical seal retains hydraulic density. The actual pressure in the cavity 6 corresponds to the residual ρ _sp , which remains in the fuel supply system after fuel injection and needle landing. In order to provide a more reliable density of the conical seal, the design pressure is assigned a large ρ _sp . For the proposed sprayer, it is recommended to take ρ _t = 0.5-ρ _pi , where ρ _pi is the known needle lifting pressure. The sealing force P _y is equal to

P _y = (P _n -P _t ) ⋅ sinα,

- сила затяжки пружины форсунки;Where

- tightening force of the nozzle spring;

- сила давления топлива на иглу, уменьшающая уплотняющее воздействие, где ρ_т - расчетное давление, до которого коническое уплотнение сохраняет гидравлическую плотность. Удельное контактное уплотняющее давление в коническом уплотнении равно

- the pressure force of the fuel on the needle, which reduces the sealing effect, where ρ _t is the design pressure to which the conical seal retains hydraulic density. The specific contact sealing pressure in the conical seal is

ρ _y = P _y / F _n ,

where F _n = π⋅ (d _o -b _n sinα) ⋅b _n is the contact area in the conical seal.

, создаваемое иглой на седло, составит:Relative specific contact sealing pressure

created by the needle on the saddle will be:

where d _and , d _o , b _n , cm,

ρ _pi , ρ _t , ρ _y , kg / cm ² . The study (VG Kuzkin On sealing forces and hydraulic permeability of precision joints; XVI International Symposium “Ship Power Plants”, Poland - Gdansk, 1994, p.165 ... 175) showed that a precision (without laying) seal, which is the proposed conical seal, retains density only if the conditions are met:

where ∑Ra = R _an + R _ac is the total roughness of the sealing-shock-absorbing belt of the needle R _an and the surface of the seat cone R _ac in microns;

b _n - belt width in mm.

When assigning the width of the belt b _n, it is recommended to choose its value close to the actual values of the width of the contact zone of conventional nozzles when they are rejected for the tightness of the conical seal formed as a result of the destruction of the surface layers of the saddle and needle metals.

Dependence (3) is presented in FIG. 2 in a graphical form convenient for practical use.

A specific example of the selection of parameters in the manufacture of the proposed atomizer nozzle.

=1,98; ∑Ra≤0,163 мкм. При этом величина сближения уплотнительно-амортизирующего пояска, при котором происходит практически полное торможение иглы, составляетFor NVD-48A engine sprayers (ЧРН 32/48), the width of the contact zone when rejecting them according to the density of the conical seal is in the range 0.5 ... 0.7 mm. Assigning the proposed atomizer b _n = 0.6 mm and knowing the necessary values and operation parameters of this atomizer nozzle: d _and = 8.0 mm; d _o = 4.7 mm; ρ _pi = 280 kg / cm ² ; 2α = 60 °, assuming ρ _t = 0.5⋅ρ _pi , based on dependencies (2) and (3), we obtain the conical sealing parameters that are consistent with each other: b _n = 0.6 mm;

= 1.98; ∑Ra≤0.163 μm. In this case, the approximation value of the sealing-shock-absorbing belt, at which the needle is almost completely braked, is

S = 0.82 (b _n ) ^1.46 = 0.39 μm, which exceeds ∑Ra = 0.163 μm and indicates a soft fit of the needle and an increase in the life of the conical seal and the atomizer as a whole.

и ∑Ra) с помощью графического представления зависимости (3) показана на фиг.2 (точка «а»).The scheme for determining the agreed parameters of the proposed atomizer (b _n ,

and ∑Ra) using a graphical representation of the dependence (3) is shown in figure 2 (point "a").

Claims (8)

A nozzle nozzle for a diesel engine, comprising a body with a conical seat and a needle placed therein, containing a throttle cone with an angle greater than the seat angle, a shock-absorbing element, characterized in that the needle is made with a conical sealing-shock-absorbing belt with a cone angle equal to the angle of the seat cone, moreover, the width of the belt is related to the relative specific contact pressure of the needle on the saddle and the total roughness of the contacting surfaces of the sealing-shock-absorbing belt and saddle as follows:

, where b _n - the width of the sealing shock-absorbing belt, mm,

- the relative specific contact pressure of the needle on the saddle, ∑Ra is the total roughness of the contacting surfaces of the sealing-shock-absorbing belt and saddle, μm, ρ _t - design pressure to which the conical seal retains hydraulic density, kg / cm ² , ρ _y - specific contact sealing pressure in the conical seal, kg / cm ² , and the approximation value S of the surface of the sealing-shock-absorbing girdle with the surface of the saddle, at which the shock-absorbing effect is manifested and the needle is sharply braked, is greater than aRa and is related to the width of the sealing-shock-absorbing girdle b _{n by the} dependence S = 0.82 (b _n ) ^1.46 .

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