The present invention relates to a fuel injection valve for supplying fuel to an internal combustion engine, and in particular to a fuel injection valve that realizes balance between low fuel consumption and high output.
In recent years, regulations related to automotive fuel consumption have become strict, and low fuel consumption has been desired for automotive internal combustion engines. Meanwhile, high output has also been desired for the internal combustion engines. In order to achieve the low fuel consumption and the high output simultaneously, an injection amount control range needs to be expanded so as to conform to a wide operation region of the engine. In order to do so, it is desired that a lift amount (a stroke) of a valve body that determines a cross sectional area of a flow passage in a fuel injection section is variable.
As a fuel injection valve for realizing this, a configuration having two movable elements is disclosed in PTL1.
PTL1: JP-A-2004-225659
However, in PTL1, objects moved by the moving elements differ, and the stroke is not generated in two stages.
An object of the invention is to provide a fuel injection valve that allows a stroke amount of a valve body to be variable in order to expand a control range of a fuel injection amount that is required for a wide operating state of an engine, such as balance between low fuel consumption and high output.
In order to solve the problem, the invention adopts a configuration as follows.
In a fuel injection valve that includes: a valve body provided to be slidable; a movable element for cooperating with the valve body; a fixed iron core provided at a position to oppose the movable element; a valve seat member formed with an annular valve seat; and a coil for displacing the movable element and causing the valve body to be seated on or unseated from the valve seat, a plurality of the movable elements is engaged with the one valve body.
According to the fuel injection valve of the invention, the control range of the fuel injection amount is expanded by constituting the plural strokes, and thus optimum fuel injection can be realized in the wide operation region of the engine.
A description will hereinafter be made on a fuel injection valve according to a first embodiment of the invention with reference to
First, a description will be made on an overall configuration and a flow of fuel in a fuel injection valve 1.
The fuel injection valve 1 is configured by including: an injection hole constituting member 110 that has a fuel injection hole 110′ for injecting the fuel; a nozzle body 111 that contains a valve body 106 driven vertically; and an inner fixed iron core 100, a first movable element 107, a second movable element 105, an outer fixed iron core 113, an upper fixed iron core 114 that constitute a magnetic circuit 120 in the case where a valve opening signal is provided to a coil 115 through a terminal 119. Furthermore, the fuel injection valve 1 is configured by including: an upper spring 116, an upper side of which is supported by a spring retaining pin 117, and that generates a force on a lower side, the spring retaining pin 117 causing a force to be acted on the valve body 106 at a time of non-energization; and a lower spring 108 that is supported by a receiving section 111a of the nozzle body 111 and applies an upward force via the first movable element 107.
The fuel that flows in from a fuel inflow section 100′ connected to an undepicted fuel pipe flows along a center axis 1′ of the fuel injection valve, flows through a fuel passage 106a that is positioned at the upper center of the valve body 106 and a transverse fuel passage 106b that communicates in a radial direction, flows through a space 111′ between the nozzle body 111 and the valve body 106, flows through a fuel passage section 109a of a guide member 109 that is positioned at a tip of the fuel injection valve 1, reaches a seat section 106c on which the valve body 106 and the injection hole constituting member 110 are seated, and, at a time of energization, flows through a gap produced in the seat section 106c. In this way, the fuel is injected from the fuel injection hole 110′.
Next, a description will be made on configurations of the first movable element 107, the second movable element 105, and the valve body that function as a movable section.
It is characterized that the second movable element 105 in the invention has a circular section 105a that serves as a magnetic attraction surface and an outer periphery extending section 105b that extends from the circular section to an outer periphery. In addition, an inner diameter hole 105c that is used to be integrated with an outer diameter section of the valve body 106 by press fitting or the like is perforated. In this way, the second movable element 105 and the valve body 106 operate as the integrated movable body 201.
The first movable element 107 has an upper surface 107e that is paired with each of the fixed iron cores on an inner peripheral side and an outer peripheral side, and a projected section 107f is provided in a portion thereof. The projected section 107f suppresses a sticking force by the fuel that exists between the fixed iron core and the upper surface 107e of the first movable element. In addition, the first movable element 107 has an intermediate surface 107a that comes in contact with and is fitted with a lower surface 105d of the second movable element in the movable body 201. The intermediate surface 107a has: an axial fuel passage 107c that serves as a fuel passage at a time of contact with the movable body 201; and a radial fuel passage 107d, and suppresses generation of the sticking force by the fuel. A lower surface 107b of the first movable element comes in contact with the lower spring 108 and generates an upward force. Furthermore, a hole 107g is perforated at the center of the first movable element 107 and penetrated by an outer peripheral section 106d of the valve body 106 in the movable body 201.
Next, a description will be made on the fixed iron cores for attracting the first and second movable elements. It is characterized that a spacer 112 is provided between the inner fixed iron core 100 and the outer fixed iron core 113 in the fuel injection valve of the invention. There is a case where the spacer 112 is joined to the inner fixed iron core 100 and the outer fixed iron core 113 by welding, or there is a case where the spacer 112 is coupled thereto by tension joining of metals in crushed sections 112a, b that is caused by a load from an upper direction. While the inner fixed iron core 100 and the outer fixed iron core 113 are magnetic materials, the spacer 112 is a non-magnetic material. If the spacer 112 is the magnetic material, the magnetic circuit 120 as in
Hereinafter, a description will be made on an operation principle for achieving two types of stroke, which is the characteristic of the invention. It is characterized that this operation constitutes large and small lifts by using a difference between the magnetic attractive forces generated in the first movable element 107 and the second movable element 105, the difference being generated by a current supplied to the coil.
First, a description will be made on a configuration in the valve closed state by using
Next, a description will hereinafter be made on a configuration in which a small lift amount of the two lift amounts is achieved. In the fuel injection valve according to the invention, when the current is supplied to the coil 115, the first movable element 107 is attracted upward, the lower end surface 5100 of the inner fixed iron core 100 and the outer fixed iron core 113 comes in contact with the upper end surface 5107 of the first movable element, and the small stroke is constituted. If restated by a relationship of the action of the force, it will be as described as below.
As depicted in
As depicted in
A description will be made on displacement of the valve body 106 by using
Next, a description will hereinafter be made on a configuration in which a large lift amount of the two lift amounts is achieved by using
As depicted in
As depicted in
At this time, as described above in
At the time of the large lift, a gap 712 is constructed between the first movable element 107 and the second movable element 105. When the fuel injection valve has the cross section in
In the method for adjusting the lift amounts according to the invention, either one of the large lift amount and the small lift amount is determined in advance. Then, the other of the lift amounts is determined from a difference in height between the first movable element 107 and the second movable element 105. Desirably, it is preferred that the large lift amount is determined after the small lift amount is determined in advance. The reason for this is because a rate of fluctuations in the injection amount of the fuel injection valve, which corresponds to an adjustment error of the lift, is increased when the lift amount is small.
A description will hereinafter be made on a case where the two types of the lift is switched in the fuel injection valve for generating the two types of the lift when the fuel injection valve is installed in an undepicted internal combustion engine. The case where a small injection amount is required by decreasing the lift amount mainly occurs when a rotational speed of the internal combustion engine is low, when generated torque of the internal combustion engine is low, and when fuel injection pressure is low. In other words, in the case where a certain threshold is past on the basis of information of each of an airflow sensor for sensing an intake air amount, a crank sensor for sensing the rotational speed, and a pressure sensor for sensing fuel injection pressure, the waveform is switched to that for the small stroke. In addition, in the case where an accelerator opening degree is suddenly decreased in an operation state that the accelerator opening degree is high, the rotational speed is high, and the torque is also high, it is desired to switch the waveform to that for generating the small stroke even with the high fuel pressure.
In this example, the intake air amount, the rotational speed of the internal combustion engine, the fuel injection pressure, the accelerator opening degree are sensed, and the waveform of the current that is supplied to the fuel injection valve is switched by the threshold. However, when the similar effect can be obtained by using another information, switching is possible.
In this example, the structure in which the second movable element 105 and the valve body 106 are originally the separate members but are integrated by press fitting or the like is adopted. However, even with an originally integrated structure, a configuration thereof will not be limited as long as the second movable element 105 and the valve body 106 are attracted to the inner fixed iron core 100 and the outer fixed iron core 113, and the fuel can be sealed in the valve seat section 106c.
In this example, the description is made on the current waveform that does not retain the peak current at the time of the small stroke and the waveform that retains the peak current at the time of the large stroke. However, the operational effects according to the invention are not impaired with another current waveform as long as it is a current waveform that allows the movable element to constitute the two types of the stroke.
In this example, the spacer 112 as the non-magnetic member is constructed as a single part. However, even when this is constructed of plural members, the operational effects according to the invention are not impaired.
Number | Date | Country | Kind |
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2013-010731 | Jan 2013 | JP | national |
This application is a continuation of U.S. application Ser. No. 15/364,846, filed Nov. 30, 2016, which is a continuation of U.S. application Ser. No. 14/763,029, filed Jul. 23, 2015, which is a 371 of International Application No. PCT/JP2014/050272, filed Jan. 10, 2014, which claims priority from Japanese Patent Application No. 2013-010731, filed Jan. 24, 2013, the disclosures of which are expressly incorporated by reference herein.
Number | Date | Country | |
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Parent | 15364846 | Nov 2016 | US |
Child | 15640838 | US | |
Parent | 14763029 | Jul 2015 | US |
Child | 15364846 | US |