RU2769207C2 - Fuel injector - Google Patents

Abstract

FIELD: engine building.

SUBSTANCE: invention can be used in fuel supply systems of internal combustion engines (ICE). Disclosed fuel injector (100) comprises nozzle body (102) and spraying unit (104) fixed on it, having one or more nozzle holes for fuel discharge into the combustion chamber. At that, in fuel injector (100) housing (102) there is spring (106) having a variable diameter of turns and a variable pitch to control the amount of fuel injected into the combustion chamber, depending on the engine operating mode. Spring with variable diameter of turns and variable pitch provides variable speed of nozzle sprayer needle lifting against spring force. Variable speed of needle rise determines the change in the amount of fuel injected into the combustion chamber.

EFFECT: such change in the amount of injected fuel leads to reduction of harmful emissions and reduction of fuel consumption for a certain operating mode of the engine.

1 cl, 4 dwg

Description

The field of technology to which the invention belongs

The invention relates to a fuel injector.

State of the art

The fuel injector (10) is an important component of the fuel system for injecting fuel into the engine's combustion chamber. In FIG. 1 shows in section a fuel injector (10) known from the prior art. The fuel injector (10) contains the body (12) of the injector forming its outer casing. The fuel injector (10) also contains a spray assembly (14) fixed on the injector body (12). The spray assembly (14) contains a spray gun (14a) and a needle (14b). The needle (14b) is located inside the atomizer (14a). The atomizer (14a) has one or more nozzle holes for spraying fuel in the form of a fine flame. A spring (16) is located in the body (12) of the nozzle, which provides opening and closing of the nozzle holes by moving the needle (14b) in the atomizer (14a) between its opening and closing positions. The fuel injector (10) has an inlet (18) through which fuel enters the atomizer pocket (14a). As the fuel pressure builds up in the nozzle pocket, the needle (14b) rises.

US 5,769,319 discloses a closed fuel injector comprising a housing with a cavity including an atomizer pocket and a nozzle opening communicating with one end of the atomizer pocket for discharging fuel into a combustion chamber, a locking element located in the atomizer pocket near the nozzle opening, and control means. flow rates, providing variation of the fuel flow through the nozzle hole and including a throttle passage formed in the locking element made in the form of a needle to restrict the flow of fuel entering the atomizer pocket, so as to vary the rate of fuel pressure increase in the atomizer pocket.

Brief description of the drawings

Fig. 1 is a sectional view of a prior art fuel injector.

Fig. 2 is a sectional view of a fuel injector according to the invention in one embodiment.

Fig. 3 is a graph showing the amount of fuel injected as a function of engine speed for the prior art.

Fig. 4 is a graph showing the amount of fuel injected as a function of engine speed in one embodiment of the present invention.

Detailed description of embodiments of the invention

In FIG. 2 shows a sectional view of the fuel injector (100) of the invention in one embodiment.

The fuel injector (100) comprises an injector body (102) and a spray assembly (104) fixed on the injector body (102) and having one or more nozzle holes for injecting fuel into the combustion chamber. The fuel injector (100) is characterized in that in the injector body (102) there is a spring (106) having a variable coil diameter and a variable pitch to control the amount of fuel injected into the combustion chamber, depending on the engine operation mode.

The design of the fuel injector (100) is discussed in more detail below.

The housing (102) of the fuel injector (100) forms its outer casing. The injector body (102) has a cavity (102a) in which the other components of the fuel injector (100), discussed below, are located.

The fuel injector (100) also includes a spray assembly (104) attached to the injector housing (102). The spray assembly (104) contains a spray gun (104a) with a spray pocket (104b) and a needle (104 c). The needle (104c) is located in the pocket (104b) of the atomizer. The atomizer (104a) has one or more nozzle holes in communication with the combustion chamber for injecting into the combustion chamber the fuel located in the pocket (104b) of the atomizer. The needle (104 c) is movable in the pocket (104b) of the atomizer so as to open and close the nozzle holes.

In the body (102) of the injector there is an inlet (108) for inlet into the pocket (104b) of the atomizer of fuel coming under high pressure through the pressure pipe from the fuel pump.

The atomizing unit (104) has a thread on its inner surface, by means of which the atomizing unit (104) is fixed on the nozzle body (102) in the form of a union connection.

The fuel injector (100) features a spring (106) located in its housing (102). That is, the spring (106) is located in the cavity (102a) of the body (102) of the nozzle. The spring (106) reciprocates the needle (104c) in the atomizer pocket (104b) between opening and closing needle positions during fuel injection. In addition, the spring (106) is preloaded when the spray assembly (104) is screwed onto the nozzle body (102).

In one embodiment of the invention, the feature of the spring (106) is that it has a variable coil diameter, a constant wire diameter, and a constant pitch. The coil diameter is the size of the coil across the spring. The number of coils a spring has is determined based on factors such as needle travel, fuel injection amount required, and spring rate. Variable coil diameter means that one or more coils of the spring has a different diameter than the other coils of the spring. In this embodiment, the diameter of the coils at the top and bottom of the spring (106) is smaller than the diameter of the coils closer to the middle of the spring (106). It should be noted that in this embodiment, the diameter of the coils of the spring (106) varies from 3.5 to 7.0 mm. The wire diameter is the size of the wire that the spring (106) is made of across the wire. The pitch is the distance between any two adjacent coils of the spring (106). A constant pitch means that the distance between adjacent turns is the same.

In another embodiment of the invention, the feature of the spring (106) is that it has a variable pitch, a constant coil diameter, and a constant wire diameter. A variable pitch means that the distances between different adjacent coils differ from each other, and a constant coil diameter means that the diameter of all coils of the spring is the same. In this embodiment, the pitch of the spring (106) at the top and bottom is less than the pitch of the spring (106) closer to its middle. The spring pitch value in this embodiment varies from 1 to 2 mm.

However, the spring pitch should be distributed over the coils so that the total length of the spring (106) remains approximately 27.2 mm.

In yet another embodiment of the invention, the spring (106) is characterized by having both a variable coil diameter and a variable pitch with a constant wire diameter. It should be noted that in all three embodiments of the invention, the wire diameter is constant.

The fuel injector (100) also includes a plate (110) resting on the spacer (112) and located in the cavity (102a) of the injector housing (102). The poppet (110) is also used to hold the spring (106) at one end and to transmit the movement of the needle (104 seconds) to the spring (106). The spacer (112) is located between the body (102) of the nozzle and the spray assembly. The spacer (112) is used to set the maximum lift, i.e. stroke, needle (104 s).

The operation of the fuel injector (100) is explained below.

The fuel pump increases the pressure of the fuel coming from the fuel tank. Pressurized fuel is directed to the fuel injector (100). The pressurized fuel enters the atomizer pocket (104b) through the inlet port (108). Thus, pressurized fuel accumulates in the atomizer pocket (104b). Accumulating in the pocket (104b) of the atomizer, the pressurized fuel creates a force on the needle (104 s). As a result, the needle (104 s) tends to create a compressive force against the spring force. Once the compressive force generated by the fuel pressure exceeds the spring force of the preloaded spring, the spring (106) will compress and the needle (104c) will rise to open the nozzle holes adjacent to the atomizer pocket (104b). When the nozzle openings are opened, pressurized fuel is injected into the combustion chamber.

When the needle is raised (104 s), due to the presence of a spacer (112) located between the body (102) of the nozzle and the atomizer (104a), the needle (104 s) can move until it reaches the bottom surface of the spacer (112) . This allows you to adjust the stroke of the needle. The lift of the needle is the distance traveled by the needle (104 s) from the closing position to the opening position. In FIG. 2 the needle is shown in the closed position.

The maximum needle lift (104 s) is achieved when the top surface of the needle (104 s) rests against the bottom surface of the spacer (112). The needle guide (104d) moves inside the spacer (112).

As the needle (104 s) rises against the force of the spring, the spring (106) begins to compress. When the spring (106) has a variable coil diameter and a variable pitch, the speed at which the needle (104 s) rises against the spring force changes for a particular motor mode. This speed is also called the needle lift speed (104 s). This change in needle lift speed (104 s) results in a change in the amount of fuel injected into the combustion chamber. For a certain mode of engine operation, the required amount of fuel is known from the characteristics stored in the memory of the control unit. Therefore, the distance that the needle (104 s) must rise in order for the fuel injector (100) to inject the required amount of fuel is also known. It should be noted that the use of spring (106) provides a change in the speed at which the needle (104 s) rises against the spring force for this particular engine operation, however, the needle lift height (104 s) remains unchanged for this particular engine operation. . In other words, due to the use of the spring (106), the time required for the needle (104 s) to rise to this specific height is changed.

Thus, the spring (106) having a variable coil diameter and a variable pitch provides a variable needle lift speed (104 sec) against the spring force. This variable needle lift rate results in a change in the amount of fuel injected into the combustion chamber compared to a prior art spring having a constant coil diameter and a constant pitch. Such a change in the amount of injected fuel leads to a decrease in harmful emissions and a decrease in fuel consumption for a certain engine operating mode. The change in the amount of fuel injected into the combustion chamber will be explained in more detail with reference to FIG. 3.

In FIG. 3 and 4 are graphs showing the amount of fuel injected as a function of engine speed.

In FIG. 3 shows the dependence of the amount of injected fuel on engine speed known from the prior art. In this case, the fuel injector (10) contains a spring (16) having a constant coil diameter, a constant pitch and a constant wire diameter. On the graph shown in Fig. 3, the horizontal axis represents the lift of the needle of the fuel injector (10) and the vertical axis represents the amount of fuel injected into the combustion chamber.

As noted above, the needle (14b) is movable between closing and opening positions. The lift of the needle is defined as the height to which the needle (14b) is raised relative to its closing position.

The amount of fuel injected into the combustion chamber is expressed in cubic centimeters per 30 seconds, while needle lift is expressed in millimeters.

On the graph shown in Fig. 3, the sloping straight line (302) represents a linear relationship between needle lift and the amount of fuel injected into the combustion chamber. That is, if the needle rises high, then the amount of fuel injected into the combustion chamber will be large.

The graph shown in Fig. 4 represents the relationship between the amount of fuel injected and the lift of the needle for a fuel injector (100) with a spring (106) having a variable coil diameter and/or a variable pitch to control the amount of fuel injected into the combustion chamber, depending on the engine operating mode. The horizontal axis represents the lift of the needle, expressed in millimeters. The vertical axis represents the amount of fuel injected into the combustion chamber, expressed in cubic centimeters per 30 seconds.

Graph (402) represents the relationship between the amount of fuel injected and the lift of the needle. In plot (402), the relationship between fuel injection amount and needle lift is non-linear. Such non-linearity is ensured by the variable speed of lifting the needle for a certain mode of engine operation (speed and torque). This is achieved by using a spring (106) having a variable coil diameter, either a variable pitch, or both a variable coil diameter and a variable pitch. The lifting speed of the needle is variable due to the fact that the spring (106) has a variable coil diameter and a variable pitch. Variable needle lift speed reduces the amount of fuel injected. This reduction in the amount of fuel injected results in lower emissions and reduced fuel consumption. Thus, for a certain mode of engine operation, the needle lift and the amount of fuel injected during this lift are predetermined. Through the use of a spring (106) having a variable coil diameter and a variable pitch, a variable needle lift rate is provided, which changes the amount of fuel injected into the combustion chamber. However, the height to which the needle rises (104 s), i.e. needle lift remains unchanged for this specific engine operating mode. In other words, for this particular mode of operation of the engine, the speed at which the needle rises (104 s) changes.

Thus, the present invention provides a fuel injector (100) characterized by a spring (106) having a variable coil diameter and a variable pitch. The use of such a spring (106) provides a change in the lifting speed of the needle for a certain mode of engine operation. This variable needle lift rate provides a change in the amount of fuel injected into the combustion chamber. Also, by providing a variable needle lift rate, the amount of fuel injected into the combustion chamber is reduced. This avoids the injection of excess fuel, which leads to an increase in harmful emissions and an increase in fuel consumption. Thus, the fuel injector (100) according to the invention provides a reduction in harmful emissions and a reduction in fuel consumption.

The embodiments of the invention discussed above in the description are illustrative only and do not limit the possibilities of carrying out the invention. Thus, a variety of choices exist regarding the type of nozzle body and the type of spray assembly. The scope of protection of an invention is determined only by its claims.

Claims (2)

1. A fuel injector (100) containing a body (102) of the injector and a spray assembly (104) mounted on the body (102) of the injector and having one or more nozzle holes for injecting fuel into the combustion chamber, characterized in that in the body (102 ) of the injector there is a spring (106) having a variable diameter of coils and a variable pitch to control the amount of fuel injected into the combustion chamber, depending on the engine operating mode. 2. The fuel injector (100) of claim 1 wherein the spring (106) is in a preloaded state.

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