JP4049482B2 - Fuel injection device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel injection device, and more particularly to a fuel injection device in which a fuel injection valve and a switching valve are integrated.
[0002]
[Prior art]
As a diesel engine fuel injection device, a high-pressure fuel accumulated in an accumulator is stably supplied to each cylinder of the engine so that the engine performance can be improved in a wide operating range from a low speed range to a high speed range ( Common rail system). Even when such a fuel injection device is used, if the fuel injection rate immediately after the start of fuel injection is excessive, rapid explosion combustion is performed in the early stage of combustion, which not only increases engine noise but also in exhaust gas. Nitrogen oxide (NOx) increases. In order to solve such a problem, an accumulator fuel injection apparatus that injects fuel at a lower fuel injection rate in the initial stage of each fuel injection cycle has been proposed.
[0003]
As shown in FIG. 4, this accumulator fuel injection device is connected and supplied via a high-pressure accumulator 2 for accumulating high-pressure fuel pressurized by a fuel pump 1, and a high-pressure accumulator 2 and a fuel passage 11. A fuel injection valve 3 for injecting the fuel into the engine combustion chamber, a pressure switching valve 4 for controlling discharge of the high-pressure fuel in the high-pressure accumulator 2 to the downstream side of the fuel passage 11, and A low pressure accumulator 7 that stores fuel and is connected to a fuel passage 11 downstream of the pressure switching valve 4 via a branch passage 12 and an oil passage in which an orifice 5 and a check valve 6 are connected in parallel; The pressure control valve 8 is connected to the fuel passage between the pressure accumulator 7 and the fuel tank 10 and controls the fuel pressure of the low pressure accumulator 7.
[0004]
Until the fuel injection start timing comes, both the pressure switching valve 4 and the fuel injection timing control on-off valve 15 of the fuel injection valve 3 are closed, and the downstream side of the orifice 5 and the check valve 6 is on the downstream side. Low pressure fuel is supplied from the low pressure accumulator 7 to the branch passage 12 and the fuel passage 11 downstream of the pressure switching valve 4, and this low pressure fuel is supplied to the pressure control chamber 3 a and the fuel chamber 3 b of the fuel injection valve 3. . When the fuel injection start time arrives, the on-off valve 15 is opened to open the fuel injection valve 3 to inject low-pressure fuel to perform low-pressure initial injection (hereinafter referred to as “low-pressure injection”), and the low-pressure injection period has elapsed. At that time, the pressure switching valve 4 is opened to inject high-pressure fuel from the high-pressure accumulator 2 to perform high-pressure main injection (hereinafter referred to as “high-pressure injection”), and when the injection end time comes, the on-off valve 15 is closed. Then, the fuel injection valve 3 is closed and the pressure switching valve 4 is closed. That is, the pressure switching valve 4 switches the low pressure accumulator 7 and the high pressure accumulator 2 during fuel injection to control the fuel injection rate waveform.
[0005]
The low-pressure injection causes the combustion in the initial stage of the fuel injection period to be performed relatively slowly, reducing the amount of NOx in the exhaust gas, and the fuel injection rate rapidly falls at the end of the fuel injection. Emissions of smoke (smoke) and particulates (particulate matter PM) are reduced.
After the pressure switching valve 4 is closed, high-pressure fuel accumulated between the pressure switching valve 4 and the fuel chamber 3a of the fuel injection valve 3 is introduced into the low-pressure accumulator 7 through the orifice 6 and the pressure control valve 8 is set to duty. By controlling, the fuel of the low pressure accumulator 7 is discharged to the fuel tank so that the fuel pressure of the low pressure accumulator 7 becomes a predetermined pressure.
[0006]
[Problems to be solved by the invention]
In the pressure accumulation type fuel injection device having the above configuration, piping such as the fuel passage 11 connecting the pressure switching valve 4 and the fuel injection valve 3 and the branch passage 12 connecting the fuel passage 11 and the low pressure accumulator 7 are necessary. is there. For this reason, the occupied space of the system of the whole fuel-injection apparatus increases, and real machine mounting property falls. In particular, when considering the arrangement on a cylinder head 71 of a four-valve diesel engine having two intake and exhaust valves, it is essential to make the system compact.
[0007]
Further, since the fuel passage length of the fuel passage 11 between the pressure switching valve 4 and the fuel injection valve 3 and the branch passage 12 between the check valve 6 and the fuel passage 11 is long, Due to the dead volume of the fuel (indicated by an arrow), there is a problem that the responsiveness of the injection pressure control in which the low pressure injection and the high pressure injection are switched during the injection and selectively injected is deteriorated.
[0008]
The pressure switching valve wears the seat surface due to the long-term reciprocation of the needle valve and the passage of high-pressure fuel, and as a result, leak fuel from the low-pressure accumulator increases, and further, the pressure control function during the low-pressure injection period May deteriorate. For this reason, when the pressure switching valve and the fuel injection valve are integrated into a unit, if the needle valve of the pressure switching valve deteriorates, the injection unit must be replaced even if there is no abnormality in the fuel injection valve itself. There is a problem that repair costs become high.
[0009]
Therefore, an object of the present invention is to provide a fuel injection device in which the fuel injection valve and the switching valve are integrated, and the switching valve is detachable and replaceable.
[0010]
[Means for Solving the Problems]
To achieve the above object, the present invention, a fuel injection for injecting fuel into a combustion chamber of an internal combustion engine to open the fuel injection needle valve by opening the fuel pressure acting on one end of the fuel injection needle valve A valve, a housing for accommodating the fuel injection valve, a fuel injection valve leaking fuel passage formed in the housing and returning the fuel released from one end side of the fuel injection needle valve of the fuel injection valve to the atmosphere side; A part of the high-pressure fuel from the high-pressure fuel source is removably attached to the housing, and the switching needle valve is opened to the atmosphere by opening the switching needle valve to the atmosphere by opening the switching pressure to the atmosphere. A switching valve for supplying the fuel injection valve to the fuel injection valve, the switching valve being detachably fitted in a hole formed in the housing, and a valve holder for accommodating the switching needle valve; Press from A holder that secures a sealing property between the bottom surface of the recording hole and the bottom surface of the valve holder so that the valve holder can be fixed in the hole so as not to deviate, and is formed in the housing and the valve holder through the bottom surface of the valve holder. A fuel introduction path for introducing fuel from the high-pressure fuel source to the valve holder, and a fuel that is formed in the valve holder and the housing through the lower surface of the valve holder, and leads the fuel from the valve holder to the fuel injection valve A lead-out path, and a switching valve leak fuel passage that is connected to the fuel injection valve leak fuel passage in the housing in an integrated manner and returns the working pressure released from the switching needle valve to the atmosphere side. A fuel injection device is provided.
A fuel injection valve and a switching valve that supplies fuel from a high-pressure fuel source to the downstream side by opening the valve are integrally accommodated in the housing, and the switching valve is detachably mounted on the housing. When the needle valve of the switching valve is worn, the switching valve is removed from the housing and the needle valve is replaced. Thereby, the maintenance cost of the fuel injection device can be reduced.
In addition, the leak path of the two solenoid valves is integrated by the integrated housing, and the leak fuel system is simplified.
[0011]
Further, by integrating the fuel injection valve and the switching valve, the fuel passage connecting them is shortened, the dead volume of the fuel passage is reduced, and the low pressure injection and the high pressure injection are selectively injected. The responsiveness of the injection pressure control is improved.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings.
1 is a cross-sectional view of a fuel injection device according to the present invention, FIG. 2 is an enlarged view of a pressure switching valve in the housing of FIG. 1, and FIG. 3 is a view showing that the fuel injection device of FIG. It is a top view of a state.
[0013]
As shown in FIGS. 1 and 3, the fuel injection device 20 includes a fuel injection valve housing (hereinafter simply referred to as “housing”) 21, a pressure switching valve 22 as a switching valve, a throttle check valve 23, a fuel injection The valves 24 are perpendicular to each other in a side view, and are arranged and housed in a line in a plan view to form an integral structure. The large-diameter pressure switching valve 22 and the fuel injection valve 24 are disposed on both sides of the housing 21 and have a small-diameter throttle. The check valve 23 is disposed between the pressure switching valve 22 and the fuel injection valve 24. Therefore, as shown in FIG. 3 , the housing 21 has a narrower (thin) width at the center part in which the check valve 23 with throttle is accommodated than on both sides in which the pressure switching valve 22 and the fuel injection valve 24 are accommodated. It has a shape.
[0014]
A hole 21 a provided on one side of the housing 21 accommodates an upper part of a needle valve (fuel injection needle valve) 30 of the fuel injection valve 24, a spring 31, and a piston 32, and a nozzle holder that houses the needle valve 30. 33 is detachably attached to the lower end of the housing 21 in alignment with the hole 21a. Above the piston 32, an opening / closing valve 35 for controlling the injection timing is screwed into the housing 21 and is detachably mounted. A pressure control chamber 37 is formed between the upper end surface of the piston 32 and the on-off valve 35. The on-off valve 35 is constituted by an electromagnetic valve.
[0015]
The holes 21b provided on the other side of the housing 21, and the valve holder 40 of the pressure switching valve 22 is detachably mounted, the switching valve needle 41 and the spring 42 is housed in the valve holder 40. Further, the valve holder 40 is provided with fuel passages 40a and 40b, which are respectively opened on the lower surface. As shown in FIG. 2, positioning holes 21e and 40e are formed facing the bottom surface of the hole 21b of the housing 21 and the bottom surface of the valve holder 40, and positioning pins 45 are fitted into these holes 21e and 40e. Are combined. With the positioning pins 45, when the valve holder 40 is inserted into the hole 21b, the fuel passages 40a, 40b and fuel passages 60, 61 provided in the housing 21 described later can be aligned and connected in communication.
[0016]
A solenoid valve 43 as a control valve is detachably mounted on the housing 21 above the valve holder 40, and a pressure control chamber 44 is formed between the upper end surface of the needle valve 41 and the solenoid valve 43. . The threaded portion of the outer peripheral surface of the holder 45 where the valve seat of the electromagnetic valve 43 is formed is detachably screwed with the threaded portion of the inner peripheral surface of the flange 21 f of the housing 21, and the valve holder 40 is interposed via the seal member 46. Is fixed in the hole 21b of the housing 21 so as not to deviate. And the thread part of the inner peripheral surface of the lower end of the case 47 of the electromagnetic valve 43 is detachably screwed and attached to the thread part of the outer peripheral surface of the flange 21f. In this way, the pressure switching valve 22 and the electromagnetic valve 43 are detachably attached to the housing 21.
[0017]
A check valve 23 with a throttle is accommodated in a hole 21 c provided in the center of the housing 21. The check valve with throttle 23 is provided with an orifice 54 a as a throttle at the center of the check valve 54. Thus, by providing the orifice 54a at the center of the check valve 54, the circuit can be simplified and downsized.
The housing 21 is provided with fuel passages 60, 61, 62, 63 and leak fuel passages 64, 65, 66. One end of the fuel passage (fuel introduction passage) 60 is opened in the bottom surface of the hole 21 b and opened in the fuel passage (fuel introduction passage) 40 a of the valve holder 40 of the pressure switching valve 22, and the other end is opened in the side surface of the housing 21. ing. One end of the fuel passage 63 is connected to the fuel chamber 36 of the fuel injection valve 24, the other end is connected to the pressure control chamber 37, and one end of the fuel passage (fuel outlet passage) 61 is opened to the bottom surface of the hole 21b. The other end of the fuel passage (fuel outlet passage) 40 b of the holder 40 is connected in the middle of the fuel passage 63. One end of the fuel passage 62 is provided in the middle of the fuel passage 61, and the other end is opened at the bottom surface of the hole 21c and connected to the check valve 23 with restriction. The leak fuels of the fuel injection valve 24, the on-off valve 35, and the electromagnetic valve 43 are collected in the leak fuel junction 67 through the leak fuel passages 64, 65, 66, and are returned to a fuel tank (not shown).
[0018]
The pressure switching valve 22, the check valve with throttle 23, and the fuel injection valve 24 are housed integrally in the housing 21 so as to shorten the length of the fuel passages 61, 62 connecting them. Accordingly, the dead volume (indicated by the arrow) of the fuel in the fuel passages 61 and 62 can be greatly reduced.
Then, by arranging the pressure switching valve 22, the throttle check valve 23, and the fuel injection valve 24 in order from the high-pressure fuel source side in the housing 21, the fuel passages 61 to 63 that connect them are arranged in order. The configuration of the fuel passages 60 to 63 from the high-pressure fuel source to the fuel injection valve 24 is simple and easy.
[0019]
The high-pressure fuel passages 60 and 61 are disposed below the valve holder 40 of the pressure switching valve 22, connect the fuel passages 40 a and 40 b and the fuel passages 60 and 61 on the lower surface of the valve holder 40, and By tightening 40 with the screw of the holder 45 from above, sealing performance is ensured. Further, the leak fuel passages 64 to 66 of the respective valves can be integrated, and the leak fuel system can be simplified.
[0020]
As shown in FIGS. 1 and 3, the fuel injection device 20 includes a cylinder head 71 of a multi-valve engine, for example, a four-valve engine, a fuel injection valve 24 positioned right above the combustion chamber 70, and a check valve 23 with a throttle. Is located between the intake valve 72 and the exhaust valve 73 on one side, and the pressure switching valve 22 is disposed on the opposite side of the intake side rocker arm 75 and the exhaust side rocker arm 76 mounted on the rocker arm shaft 74. Then, it is fixed to the cylinder head 71 by a nozzle bridge 78 as a fixing member. The fuel passage 60 of the housing 21 is connected to a high pressure accumulating chamber (not shown) as a high pressure fuel source (not shown) via a pipe 68, and the throttle check valve 23 is connected to a low pressure accumulating chamber (not shown) via a pipe 69. The
[0021]
The fuel injection device 20 accommodates the small-diameter check valve 23 with a throttle in a narrow space between the intake valve 72 and the exhaust valve 73 of the intake / exhaust multi-valve engine, thereby effectively using the space of the cylinder head 71. , Mounting on the actual machine is improved.
The operation will be described below.
In the fuel injection device 20, both the pressure switching valve 22 and the on-off valve 35 for controlling the fuel injection timing of the fuel injection valve 24 are closed until the fuel injection start timing arrives, and the check valve with throttle is closed. Low pressure fuel is supplied from the low pressure accumulating chamber to the fuel passage 62 on the downstream side of 23, the fuel passage 61 on the downstream side of the pressure switching valve 22, and the fuel passage 63, and the low pressure fuel is supplied to the fuel chamber 36 of the fuel injection valve 24. A pressure control chamber 37 is supplied.
[0022]
When the fuel injection start timing arrives, the on-off valve 35 is opened to open the fuel injection valve 24, and low pressure fuel is injected to perform low pressure injection. When the solenoid valve 43 of the pressure switching valve 22 is opened when the low pressure injection period has elapsed, the fuel in the pressure chamber 44 is discharged through the leak passage 66, and the pressure in the pressure chamber 44 is reduced. High pressure fuel from the chamber is applied as a piston working pressure to the lower portion of the needle valve 41 through the fuel passage 60 and the passage 40a, and the needle valve 41 is pushed up against the spring force of the spring 42 to open. As a result, the pressure switching valve 22 is opened, and high-pressure fuel from the high-pressure accumulator is supplied to the fuel injection valve 24 through the fuel passages 40b, 61, 63, and high-pressure injection is performed. When the injection end time comes and the on-off valve 35 is closed and the solenoid valve 43 is closed, the fuel pressure in the pressure chamber 44 becomes high, and the needle valve 41 is closed by the spring 42.
[0023]
After the pressure switching valve 22 is closed, the fuel injection device 20 causes the high pressure fuel accumulated between the pressure switching valve 22 and the fuel chamber 36 of the injection valve 24 to pass through the orifice 54a of the throttle check valve 23 and the low pressure fuel. Introduce into the accumulator.
The fuel injection device 20 has a short fuel passage 61, 62 connecting the pressure switching valve 22, the throttled check valve 23, and the fuel injection valve 24, and the dead volume of the fuel in these fuel passages is small. And responsiveness of injection pressure control when selectively injecting high pressure injection.
[0024]
When the needle valve 41 or the valve holder 40 of the pressure switching valve 22 is worn and replaced, the electromagnetic valve 43, the holder 45 and the member 46 forming the pressure control chamber are removed, and the valve holder 40 is taken out from the hole 21b of the housing 21. The needle valve 41 or the valve holder 40 is replaced. After replacing the needle valve 41 or the valve holder 40, the valve holder 40 is again inserted into the hole 21 b of the housing 21 and positioned by the positioning pin 45. Accordingly, the fuel passages 40a and 40b of the valve holder 40 and the fuel passages 60 and 61 of the housing 21 can be accurately connected to each other. Then, the holder 45 is screwed through the member 46 forming the pressure control chamber to fix the valve holder 40 to the housing 21, and the electromagnetic valve 43 is mounted. Thereby, only the needle valve 41 of the pressure switching valve 22 can be easily replaced.
[0025]
【The invention's effect】
According to the present invention, a fuel injector, and a fuel injection valve and the switching valve is mounted integrally with the housing, and by a detachable constituting the switching valve, Hakare be simplified injector, the long-term Through the use of the fuel injection device, even if the needle valve of the switching valve is worn, only the needle valve can be replaced, and the cost can be greatly reduced.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a fuel injection device according to an embodiment of the present invention.
FIG. 2 is an enlarged view of a pressure switching valve in the housing of FIG.
FIG. 3 is a plan view showing a state where the fuel injection device shown in FIG. 1 is mounted on a cylinder head of an engine.
FIG. 4 is a configuration diagram of a conventional accumulator fuel injection device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 20 Fuel-injection apparatus 21 Fuel-injection valve housing 22 Pressure switching valve 23 Check valve 24 with a throttle 24 Fuel-injection valve 40 Valve holder 40a, 40b, 60-63 Fuel path 41 Needle valve 45 Positioning pin

Claims (1)

A fuel injection valve that opens the fuel injection needle valve by injecting fuel pressure acting on one end side of the fuel injection needle valve and injects fuel into the combustion chamber of the internal combustion engine;
A housing for housing the fuel injection valve;
A fuel injection valve leak fuel passage formed in the housing and returning the fuel released from one end side of the fuel injection needle valve of the fuel injection valve to the atmosphere side;
A part of the high-pressure fuel from the high-pressure fuel source is removably attached to the housing, and the piston operating pressure of the switching needle valve is used as the piston operating pressure, and the switching needle valve is opened by releasing the operating pressure to the atmosphere. and a control valve for supplying fuel to the fuel injection valves,
The switching valve is detachably fitted in a hole formed in the housing, and receives a valve holder that houses the switching needle valve, and presses the valve holder from above, and a bottom surface of the hole and a bottom surface of the valve holder With a holder that secures the sealing performance and secures the valve holder in the hole so as not to deviate,
A fuel introduction path that penetrates the lower surface of the valve holder, is formed in the housing and the valve holder, and introduces fuel from the high-pressure fuel source to the valve holder;
A fuel lead-out path that penetrates the lower surface of the valve holder, is formed in the valve holder and the housing, and leads fuel from the valve holder to the fuel injection valve;
A fuel injection valve comprising: a switching valve leak fuel passage integrally connected to the fuel injection valve leak fuel passage in the housing and returning a working pressure released from the switching needle valve to the atmosphere side; apparatus.

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