METHOD OF CONTROLLING ELECTRONICALLY CONTROLLED FUEL INJECTION DEVICE

Abstract

A method to prevent generation of impact noise caused by an armature contacting a stopper due to a return spring and damage of the armature and a stopper without adding a part. Excitation of an electromagnetic coil 4 causes an armature 9 at a standby position to move in a plunger 7 direction so as to move the plunger 7 inserted in a pressurizing chamber 3 in a tip end direction against a return spring 8 to a level such that fuel is not injected from an injection nozzle 2. Fuel supplied from a fuel tank to the pressurizing chamber 3 through a fuel intake pipe 10 and inlet check valve 11 is pressurized and vapor included in the fuel inside the pressurizing chamber 3 is discharged to a fuel return pipeline 14 through a spill valve 12 and return passage 13. Excitation of the electromagnetic coil 4 is stopped, and then the electromagnetic coil 4 is re-excited prior to the armature 9 and plunger 7 reaching the standby position due to the return spring 8, such that the return speed of the armature 9 is reduced and an impact when the armature 9 contacts a stopper 15 is mitigated.

Claims

1. A method for controlling an electronically controlled fuel injection device, comprising: causing reciprocating motion of a plunger that is normally at a standby position in contact with a stopper based on a return spring and controlling fuel that can be injected into a pressurizing chamber using an armature that moves by means of excitation of an electromagnetic coil to pressurize fuel supplied to the pressurizing chamber and inject the fuel through an injection nozzle into an engine, and discharging vapor mixed into fuel by returning a part of the fuel supplied to the pressurizing chamber via a return passage, through a fuel return pipe, to a fuel tank, wherein when starting the engine, excitation of the electromagnetic coil causes the armature in the standby position to move in the plunger direction and the plunger is caused to move against the return spring into the pressurizing chamber to a level that does not cause fuel to be injected from the injection nozzle in the tip direction, and after discharging vapor included in the fuel supplied to the pressurizing chamber and pressurized to a fuel return pipe, excitation of the electromagnetic coil is stopped, and then the electromagnetic coil is re-excited before the return spring causes the armature and plunger to reach the standby position, reducing the return speed of the armature and mitigating the impact and reducing noise when the armature contacts the stopper.

2. The method of controlling an electronically controlled fuel injection device according to claim 1, wherein an excitation time and excitation period of the re-excitation are determined based on the biasing force of the return spring for returning the armature and plunger to a prescribed standby position.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings, which are included as part of the present specification, illustrate the presently example embodiments and, together with the general description given above and the detailed description of the example embodiments given below, serve to explain and teach the principles of the present invention.

[0019] FIG. 1 is a front vertical cross-sectional view illustrating an electronic fuel injection device used in a preferred embodiment of the present example embodiments and in a conventional example.

[0020] FIG. 2 is a front vertical cross-sectional view illustrating a cutout of an electronic fuel injection device of the embodiment illustrated in FIG. 1.

[0021] FIG. 3 is a state diagram illustrating chronological current control to an electromagnetic coil at the time of restart in a method of controlling an electromagnetic fuel injection device of the present example embodiments and the oscillation state in the electronic fuel injection device at this time.

[0022] FIG. 4 is a state diagram illustrating chronological current control to an electromagnetic coil at the time of restart in a method of controlling an electromagnetic fuel injection device of the conventional example and the oscillation state in the electronic fuel injection device at this time.

[0023] It should be noted that the figures are not necessarily drawn to scale and that elements of similar structures or functions are generally represented by like reference numerals for illustrative purposes throughout the figures. It also should be noted that the figures are only intended to facilitate the description of the various embodiments described herein. The figures do not necessarily describe every aspect of the teachings disclosed herein and do not limit the scope of the claims.

DESCRIPTION OF THE EXAMPLE EMBODIMENTS

[0024] An example embodiment of an electronically controlled fuel injection device of the present example embodiments will be described in detail below based on the drawings.

[0025] Before the present subject matter is described in detail, it is to be understood that this disclosure is not limited to the particular embodiments described, as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present disclosure will be limited only by the appended claims.

[0026] Representative examples of the embodiments described herein, which examples utilize many of these additional features and teachings both separately and in combination, will now be described in further detail with reference to the attached drawings. This detailed description is merely intended to teach a person of skill in the art further details for practicing preferred aspects of the present teachings and is not intended to limit the scope of the invention. Therefore, combinations of features and steps disclosed in the following detail description may not be necessary to practice the invention in the broadest sense, and are instead taught merely to particularly describe representative examples of the present teachings.

[0027] Moreover, the various features of the representative examples and the dependent claims may be combined in ways that are not specifically and explicitly enumerated in order to provide additional useful embodiments of the present teachings. In addition, it is expressly noted that all features disclosed in the description and/or the claims are intended to be disclosed separately and independently from each other for the purpose of original disclosure, as well as for the purpose of restricting the claimed subject matter independent of the compositions of the features in the embodiments and/or the claims. It is also expressly noted that all value ranges or indications of groups of entities disclose every possible intermediate value or intermediate entity for the purpose of original disclosure, as well as for the purpose of restricting the claimed subject matter. An example embodiment of an electronically controlled fuel injection device of the present invention will be described in detail below based on the drawings.

[0028] FIG. 1 illustrates an example of an electronically controlled fuel injection device used in implementing the method of controlling the electronically controlled fuel injection device of the present example embodiments. The structure itself and operating conditions of fuel injection are the same as those indicated in the conventional example above, and thus a detailed description will be omitted.

[0029] Next, the state diagram of FIG. 3 will be further described, which chronologically shows current control to an electromagnetic coil at the time of engine restart in the method of controlling an electromagnetic fuel injection device of the present example embodiments and an oscillation state of the electronic fuel injection device at this time. When starting an engine in a state with vapor mixed in the pressurizing chamber 3, and when the armature 9 (plunger 7) is reciprocated to discharge vapor included in fuel inside the pressurizing chamber 3 to the fuel return pipe 14 through the spill valve 12 and return passage 13 to a level that fuel is not injected from the injection nozzle 2, as in the case of the conventional example shown in FIG. 4, the pulse current (I1) is applied to excite the electromagnetic coil 4 for only time (T1) to move the armature 9, which is in the standby position due to the return spring 8 in the plunger 7 direction, and move the plunger 7, which is inserted in the pressurizing chamber 3 in the tip end direction against the return spring 8 to a level that fuel is not injected from the injection nozzle 2. The fuel supplied from a fuel tank (not shown) to the pressurizing chamber 3 via the fuel intake pipe 10 and inlet check valve 11 is pressurized to discharge the vapor included in the fuel in the pressurizing chamber 3 from the spill valve 12 to the fuel return pipe 14 via the return passage 13, and then excitation of the electromagnetic coil 4 is stopped.

[0030] Here, in the conventional example above, as shown in FIG. 4, when the current (I1) of the injection pulse is stopped, oscillation of the armature 9 (plunger 7) was generated when being pushed in the base end direction by the return spring 8 to return to the original standby position in contact with the stopper 15, and causing the armature 9 to impact the stopper 15. However, in the present example embodiment, before excitation of the electromagnetic coil 4 is stopped and the armature 9 and plunger 7 reach the standby position (position where a base end of the armature 9 contacts the stopper 15) due to the return spring 8, in other words, after a prescribed time (T2) has elapsed after stopping the excitation of the electromagnetic coil 4 illustrated in FIG. 3, a prescribed re-excitation pulse current (I2) is applied to the electromagnetic coil 4 for a prescribed time (T3) to reduce the return speed of the armature 9 against the biasing force of the return spring 8.

[0031] As a result, impact when the armature 9 contacts the stopper 15, as in the conventional example shown in FIG. 4, is mitigated, resulting in reduced noise and reduced damage to parts.

[0032] In this manner, according to the present Embodiment, when restarting the engine, the armature 9 (plunger 7) is caused to reciprocate to a level that fuel is not injected from the injection nozzle 2 to remove vapor included in the fuel in the pressurizing chamber 3. Vapor included in the fuel in the pressurizing chamber 3 is discharged to the fuel return pipe 14 via the spill valve 12 and return passage 13. The impact when the armature 9 (plunger 7) is returned to the standby position by the return spring 8 thereafter can be prevented. This prevents imparting an unpleasant noise to the user and simplifies restarting the engine when there is fuel containing vapor in the pressurizing chamber 3. Furthermore, no maintenance or repair is required for damaged parts, as impact similar to that in the conventional example is not present.

[0033] In addition, the method of controlling an electronic fuel injection device of the present embodiment does not require the attachment of a part such as a non-impact member to the stopper 15 or armature 9 as was conventionally required. The method of the present example embodiments is simply to perform electrical control in which the prescribed re-excitation pulse current (I2) is applied to the electromagnetic coil 4 for a prescribed time (T3) after a prescribed time (T2) has elapsed after excitation of the electromagnetic coil 4 is stopped, and can be easily applied to an existing electronic fuel injection device without complicating parts management and assembly.

[0034] Furthermore, the re-excitation time (T3) and excitation period (T1+T2) shown in FIG. 3 are calculated and determined based on the biasing force of the return spring 8 for returning the armature 9 and plunger 7 back to the prescribed standby position, such that the effect of re-excitation is reliably exhibited, and no wasteful power is required.

[0035] Note that the present embodiment relates to control for reciprocating the armature 9 (plunger 7) to discharge vapor included in fuel inside the pressurizing chamber 3 to the fuel return pipe 14 through the spill valve 12 and return passage 13 to a level that fuel is not injected from the injection nozzle 2 when starting the engine in a condition where the vapor is mixed in the pressurizing chamber 3. Control is easy because the present embodiment is applied when the reciprocating motion of the armature 9 (plunger 7) is relatively slow. However, it goes without saying that this also applies to normal engine operation.

[0036] Description of Referential Numerals and Codes: 1: Injection valve, 2: Injection nozzle, 3: Pressurizing chamber, 4: Electromagnetic coil, 5: Bobbin, 6: Inner yoke, 7: Plunger, 8: Return spring, 9: Armature, 10: Fuel intake pipe, 11: Inlet check valve, 12: Spill valve, 13: Return passage, 14: Fuel return pipe, 15: Stopper, 61: Spacer, 62: Cutout window, 63: Head cover