JPS60256549A - Fuel injector - Google Patents

Abstract

PURPOSE:To simplify the structure and to improve the productionability of a fuel injector for feeding fuel to the injectors fixed to respective cylinder of engine and injecting, by enabling forced circulation of fuel in the injector through single tube. CONSTITUTION:The fuel flowed through an opening 15 made at the fuel flow- in section of a flow-in tube 11 will pass through a filter 12, the inner diameter section of a spring 7 and the side port 19 of a valve 5 to the outercircumference of said valve 5 and upon opening of the valve 5, spiral flow is produced at the shaft port 20 of spiral chip 9 to be injected through a nozzle 10. The residual fuel is passed through the gap of core 3 and the plunger 6 or thrugh a hole 22 made through the plunger 6 to the outercircumference of a coil 4 then through an opening 13 made at the upper portion of core 3 and the double wall path formed with the walls of coaxially arranged flow-in and flow-out tubes 11, 18 to a fuel pipe 17. Consequently, forced circulation of fuel in an injector can be achieved through single tube structure.

Description

DETAILED DESCRIPTION OF THE INVENTION (Utilization of the invention, field) The present invention relates to a fuel injection device for use in a multi-cylinder engine,
In particular, the present invention relates to a fuel injection device having a configuration for forcibly removing air bubbles generated in an electric or magnetic fuel injection valve (hereinafter referred to as an injector) at high temperatures.

[Background of the invention]

In order to comply with regulations on harmful exhaust gases emitted from engines and to improve fuel efficiency and drivability, a microcomputer detects the operating status of the engine using various sensors and uses the detection results to determine the optimal amount of fuel to be supplied. The use of fuel injection devices that perform calculations and control is expanding.

The above fuel injection device is a multi-point fuel injection device (hereinafter referred to as MPI) in which an injector is attached to each cylinder of the engine.
(hereinafter referred to as SPI), and single point fuel injection systems (hereinafter referred to as SPI) in which one or two injectors are installed in the center of a common intake manifold for multiple cylinders.

The former MPI employs a configuration in which a fuel inflow pipe is provided at one end of each injector and connected in parallel to a common fuel pipe. Therefore, the injector is filled with fuel up to the nozzle outlet of the injector, and the amount of fuel injected into each cylinder is controlled by controlling the valve opening time according to the operating state of the engine. However, with MPI of this type of configuration, during idling operation at high temperatures or when restarting after stopping in hot weather, the injector coil may not be sufficiently cooled or may overheat due to the high temperature environment in the engine compartment. This can cause a large amount of air bubbles to form in the injector, resulting in insufficient or interrupted fuel injection, resulting in a lean air-fuel ratio to the engine, making it impossible to restart or causing poor idling. This may cause problems such as

The latter SPI also suffers from the problem of bubbles generated in the injector at high temperatures, as described above, but the structure around the injector in SPI is a bottom-feed type fuel passage configuration that circulates fuel around the nozzle. Because of this, the above problems are less likely to occur.

On the other hand, as a heat-resistant measure for the above-mentioned MPI injector, a typical configuration has been proposed in which two pipes, an inlet and an outlet, are integrally attached to the injector and a supply pipe and a discharge pipe are connected to each of them. For example, JP-A-58-
163881, JP 58-163882, JP 58-62359, JP 58-623
58, JP-A-57-122161, etc. However, these configurations have disadvantages such as poor productivity and serviceability because two pipes must be installed to each injector at the same time, high costs due to piping, and large installations requiring space. There's a problem.

[Purpose of the invention]

An object of the present invention is to solve the above-mentioned problems in MPI, improve safety and serviceability, reduce costs, and enable miniaturization by reducing installation space.

[Summary of the invention]

In order to achieve the above object, the present invention is characterized by an inflow pipe serving as a passage for supplying fuel from a common fuel pipe to each injector, and an outflow pipe serving as a passage for returning part of the fuel to the fuel pipe. and a means for forming a pressure difference at the fuel inlet portion of the inflow pipe to serve as a pressure source for forcibly circulating the fuel into the injector in response to the dynamic pressure of the fuel flow in the fuel pipe. The configuration is as follows.

[Embodiments of the invention]

A first embodiment of the present invention will be explained with reference to the sectional view shown in FIG.
(not shown) so as to receive the dynamic pressure of the fuel flow pumped from the injector and use it as a pressure source for forced fuel circulation into the injector.
An opening (A) 15 is provided at the inflow portion of the inflow pipe 11. In Fig. 1, 2 is a yoke, 3 is a core, 4 is a coil, 5 is a valve, 6 is a plunger, 7 is a spring for restoring the valve, and 8
1 is a valve seat, 9 is a swirler, and 10 is a nozzle, which constitute the injector 1. The fuel that flows in from the opening (A) 15 provided at the fuel inflow portion of the inflow pipe 11 passes through the filter (A) 12 attached to the inner diameter side of the inflow pipe 11.
Further, it passes through the inner diameter part of the restoring spring 7 and the outer periphery of the valve 5 from the side port 19 of the valve 5, and when the valve 5 is opened, it becomes a swirling flow at the oblique opening 20 of the swirler 9 and is injected from the nozzle 10.

The remaining fuel that is not injected from the nozzle 10 is passed through the gap between the nure 3 and the plunger 6, or through the hole 22 provided in the plunger 6 around the outer circumference of the coil 4, and then through the opening (B) 13 provided at the top of the core 3. Further, the fuel flows out into the fuel pipe 17 through a flow path of a double wall portion formed by the pipe wall of the inflow pipe 11 and the pipe wall of the outflow pipe 18 which are arranged concentrically. A filter (B) 14 is attached to the double wall portion.

In this embodiment, all of the fuel supplied from the fuel pump does not flow into the injector 1 through the inlet pipe 11, but the remaining fuel is sent through the fuel pipe 17 together with the fuel returning through the double wall section. The fuel is supplied to an injector (not shown) which supplies fuel to the next downstream cylinder.

As is well known, the fuel passage of MP I'e'S P,I'' uses a fuel pump to forcefully send the fuel stored in the fuel tank to the injector 1 through a damper and filter, and the fuel pressure of the injector 1 is adjusted to 1 to 3 kg/ The system uses a constant circulation fuel transport method in which the fuel is returned to the fuel tank via a fuel pressure regulator that controls the fuel pressure to approximately
Since ~90% of the fuel is returned to the fuel tank via the fuel pipe 17, the dynamic pressure applied to the opening (A) 15 provided in the inflow pipe 11 is also large. Further, even when a plurality of injectors are arranged side by side as in MPI, the fuel supplied to the injector located downstream is not overheated by the injector located upstream.

FIG. 2 is a diagram for explaining a second embodiment of the present invention,
This is the case when the pressure difference between the dynamic pressure of the fuel flow experienced by the inlet pipe and the back pressure created in the outlet pipe is used as the pressure source for forced fuel circulation within the injector. In FIG. 2, 31 is an outflow pipe, and 32 is an opening (
C), 33 is an inflow pipe, and 34 is a protrusion provided in the downstream region of this inflow pipe 33. Note that the opening (C) 32 is the outflow pipe 3.
It is provided on the downstream side of 1 to receive back pressure.

That is, the dynamic pressure that the inflow pipe 33 receives and the opening of the outflow 931 (
The fuel is circulated by the pressure difference with the back pressure generated in C) to cool the coil 4 of the injector 1, thereby suppressing the generation of bubbles. Further, even if air bubbles are generated, the generated air bubbles are quickly discharged by the fuel flow circulating around the outer periphery of the coil 4.

FIG. 3 is a diagram illustrating a third embodiment of the present invention, which is a pressure source for forced circulation of fuel in the injector, which combines the dynamic pressure of the fuel flow received by the inflow pipe and the static pressure generated in the outflow pipe. In this case, the upper end open surface of the outflow pipe 42 is located at the contraction part 41 of the fuel pipe 17, and the upper end open surface is cut diagonally, and the inflow pipe 4
4 is provided with an opening (CD) 43 that receives dynamic pressure.

The injector 1
The fuel is forced to circulate inside the tank.

In the embodiment shown in FIG. 3, the inflow pipe 4 is connected to the injector 1.
Although the fuel pipe 17 is provided with a fuel pipe 4 and an outflow pipe 42, the same function can be ensured by constructing a conduit corresponding to the inflow pipe and the outflow pipe by rubber molding or the like on the fuel pipe 17.

[Effects of the Invention] As described above, according to the present invention, forced circulation of fuel within the injector is enabled with a substantially single-tube configuration, resulting in cost reduction and installation by shortening the manufacturing process. Space is reduced, miniaturization is achieved, serviceability is improved, fuel pipe manufacturing is facilitated, costs are reduced and reliability is improved, and the number of installation parts is reduced by half, making fuel pipes easier to manufacture. This has the effect of preventing leaks and improving safety.

[Brief explanation of the drawing]

1, 2, and 3 are the first and second embodiments of the present invention, respectively.
．． FIG. 7 is a sectional view showing a third embodiment.

Claims (1)

[Claims] 10. In a fuel injection device that supplies fuel via a fuel pipe to an electromagnetic fuel injection valve attached to each cylinder of an engine for injection, an inflow that serves as a flow path for supplying fuel from the combustion pipe to the electromagnetic fuel injection valve. , a pipe and an outflow pipe serving as a flow path for returning part of the fuel to the fuel pipe are arranged concentrically, and the electromagnetic type A fuel injection device characterized by comprising means for creating a pressure difference that serves as a pressure source for forcibly circulating fuel within a fuel injection valve. 2. The pressure difference serving as the pressure source is a pressure difference between the dynamic pressure of the fuel flow received by the inflow pipe and the back pressure generated in the outflow pipe. fuel injector, 3. The fuel according to claim 1, wherein the pressure difference serving as the pressure source is a pressure difference between the dynamic pressure of the fuel flow received by the inflow pipe and the static pressure generated in the outflow pipe. Injection device.