JPS6239267B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection valve that can arbitrarily control fuel injection timing and injection period depending on the operating state of an engine.

Generally, a diesel engine is provided with a fuel injection valve with an injection port protruding into an engine cylinder, and is configured to intermittently inject fuel pumped from a fuel injection pump into the cylinder.

In conventional fuel injection valves, when the pressure of the fuel pumped from the fuel injection pump exceeds the set load of the nozzle spring that pushes the needle valve in the closing direction, the needle valve lifts and fuel is injected into the cylinder. The configuration is an automatic valve.

However, with this configuration, it is difficult to arbitrarily control the fuel injection timing and fuel period, and since the valve is closed by lowering the fuel pressure applied to the needle valve, it is difficult to arbitrarily control the fuel injection timing and fuel period. There is a drawback that the atomization state of the fuel deteriorates due to low-pressure injection.

The present invention has been made in view of the above-mentioned circumstances, and is a means for controlling the opening/closing operation of a needle valve.The present invention is a means for controlling the opening/closing operation of a needle valve. The system employs a configuration in which the opening and closing operations of the needle valve are controlled using hydraulic oil, which makes it possible to arbitrarily control the fuel injection timing and injection period independently of the fuel pressure supplied to the injection port. The present invention provides a fuel injection valve that ensures optimal fuel injection characteristics for the operating conditions of the vehicle.

Embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a diagram showing a fuel injection valve according to an embodiment of the present invention, and this fuel injection valve 1 is inserted into an engine cylinder (not shown). The main body 2 of this injection valve 1 is formed into a four-piece structure for convenience of manufacture (hereinafter, each step of the main body 2 is referred to as a first step, a second step, a third step, and a fourth step from the engine cylinder side. The four-stage main body 2 is axially aligned and integrally connected by a nozzle nut 3 and a knock pin 4. That is, a first step part (nozzle) 2a is fitted into the tip of the nozzle nut 3 formed into a cylindrical shape by engaging a step part on the outer periphery, and a second step part 2b follows the first step part 2a. Third
The step portion 2c is fitted into the nozzle nut 3 adjacent to it, and in this state, the nozzle nut 3 is screwed into the fourth step portion 2d with the threaded portion 3a, and the first, second and third step portions 2a are screwed into the nozzle nut 3. , 2b, 2c are connected by tightening them together.

A fuel injection port 4 facing into the engine cylinder is bored in the front end surface of the first stage portion 2a. First step part 2a
A needle valve 5 is slidably inserted into the interior along the axis, and this needle valve 5 is connected to a valve seat 6 communicating with the injection port 4.
The injection port 4 is opened and closed by the user sitting and taking off from the seat. A fuel chamber 7 is formed in a portion of the first stage portion 2a adjacent to the valve seat 6, and this fuel chamber 7 includes:
The other end is attached to a fuel injection pump (not shown) to the fourth stage section 2d.
One end of a fuel supply passage 8 communicating with an injection pipe attachment port 8a attached to the fuel supply passage 8 is open.

A cylinder chamber 9 is formed along the axis in the second stage portion 2b of the main body 2, and a control piston 10 is integrally connected to the needle valve 5 and is slidably fitted into the cylinder chamber 9. It is inserted. The cylinder chamber 9
A first control piston 10 formed on the needle valve 5 side of the control piston 10 of
A working hydraulic pressure supply passage 11 whose other end communicates with a working hydraulic pressure supply device to be described later communicates with the chamber 9a.On the other hand, a second hydraulic pressure supply passage 11 formed on the side opposite to the needle valve 5 of the control piston 10 in the cylinder chamber 9 communicates A spring 12 is mounted in the chamber 9b so as to constantly bias the control piston 10 in the direction of the needle valve 5 via a pair of spring receivers 13 and 13a. Also, this second chamber 9b
is communicated with one end of a ventilation passage 14 whose other end communicates with the atmosphere. A pressure receiving surface 10a is formed at the end of the control piston 10 on the needle valve side, and a pressure receiving surface 5a is formed at the end of the needle valve 5 on the injection port 4 side.

A second cylinder chamber 15 is formed along the axis in the latter half of the third stage portion 2c of the main body 2, and a pressure piston 16 is connected to the control piston 10 within this second cylinder chamber 15. It is formed integrally and is slidably inserted. Control piston 1 of the pressure piston 16 of the second cylinder chamber 15
The first chamber 15a formed on the zero side communicates with the second chamber 9b of the first cylinder chamber 9, which communicates with the atmosphere. On the other hand, one end of a branch passage 17 whose other end communicates with the fuel supply passage 8 communicates with a second chamber 15b formed on the side opposite to the control piston 10 of the piston 16 in the second cylinder chamber 15. The pressure receiving surface 16a at the rear end of the pressure piston 16 is connected to the needle valve 5.
The pressure receiving area is set to be approximately equal to the cross-sectional area of the shaft portion of the pressure piston 16 and the needle valve 5.
and are mutually balanced by the fuel pressure when the valve is opened. Further, the pressure receiving surface 10a of the control piston 10 is the pressure receiving surface 16a of the pressure piston 16.
It is set to have a much larger pressure receiving area.

In addition to the attachment port 8a of the fuel supply path 8, the fourth stage portion of the main body 2 includes an inlet 11a of the working pressure supply path 11 and an atmosphere opening port 14 of the ventilation path 14.
a are formed respectively.

FIG. 2 shows a partial view of the fuel injection valve 1 shown in FIG. 1 cut at different phase angles, and as shown in FIG. In this case, rod 18 is connected to main body 2.
The rod 18 is slidably mounted in a guide hole 19 bored parallel to the axis between the third step portion 2c and the fourth step portion 2d, and a magnetic material 20 is attached to the free end of the rod 18. is fixed. A coil 21 serving as a position sensor is provided in a portion of the fourth stage portion 2d where the magnetic body 20 is located so as to surround the magnetic body 20 with a slight gap.
1 is connected to an electronic control device to be described later, and supplies an electric signal (for example, inductance change) corresponding to the displacement of the magnetic body 20 following the control piston 10 to the electronic control device.

FIG. 3 is a circuit diagram showing an embodiment of a hydraulic pressure supply device for controlling the supply of hydraulic oil to the fuel injection valve 1 shown in FIG. 32, a relief valve 35 interposed between the discharge side of this pump 33 and the tank 32;
It includes an electromagnetic directional switching valve 36 connected to the pump 33 via a filter 34, and an electronic control device 37 that switches and controls the electromagnetic directional switching valve 36.
The electromagnetic valve 36 is a 3-port 2-position valve, and the inlet port 36a is connected to the discharge side of the hydraulic pump 33 via the filter 34, and the first outlet port 36b is connected to the tank 32 via the return path 38. The second outlet port 36c is connected to the inlet 11a of the working pressure supply passage 11 of the fuel injection valve 1 via an inlet passage 39, respectively. This solenoid valve 36 is switched to one of two positions by energizing and deenergizing a pair of solenoids 36d and 36d' in response to a control signal from an electronic control unit 37, and in the right position, the inlet port 36a and the The second outlet port 36c is connected to supply the hydraulic oil from the hydraulic pump 33 to the above-mentioned hydraulic pressure supply passage 11, and the second outlet port 36c and the first outlet port 36b are connected at the left position to supply the hydraulic oil from the hydraulic pump 33 to the aforementioned supply passage. 11 is returned to the tank 32.

The electronic control device 37 controls the electromagnetic directional control valve 36
Inside this control device 37, an injection timing signal corresponding to specifications representing the current operating state of the engine is generated based on a preset program regarding fuel injection timing and injection period. And the injection period signal is supplied to the electromagnetic valve 36 as the command signal. Here, the actual injection timing and injection period are input to the control device 37 from the coil 21 described above. The specifications representing the operating state include the engine rotation speed, the top dead center position of the piston of the engine, the engine load, etc., and the detected values from the rotation speed sensor 37a, piston top dead center sensor 37b, load sensor 37c, etc. A signal is input to electronic control unit 37. The program regarding the injection timing and injection period is determined by empirical rules or the like in accordance with the specifications of the engine to which the program is applied, and is stored in the central processing unit within the control device 37. This central processing unit performs arithmetic processing based on a preset program according to the detected value signals from the various sensors, supplies a predetermined command signal based on the processing result to the solenoid valve 36, and Then, a predetermined switching operation is performed to supply or stop the working pressure.

The operation of the fuel injection valve having the above configuration will be explained.

First, when hydraulic pressure is not supplied to the fuel injection valve 1 from the hydraulic pressure supply device 31 and fuel is not supplied to the fuel chamber 7, the needle valve 5 is moved to the valve seat simply by the biasing force of the spring 12. 6 and press the injection port 4.
is blocked. Next, even when fuel is force-fed from the fuel injection pump to the fuel chamber 7 through the fuel supply path 8, the pressure of this fuel is transferred to the second cylinder chamber 15 where the pressure receiving surface of the pressure piston 16 integral with the needle valve 5 faces.
Since the fuel is also supplied to the second chamber 15b, the needle valve 5 closes the injection port only by the biasing force of the spring 12 due to the balance between the fuel pressures in the fuel chamber 7 and the second chamber 15b. Subsequently, in the hydraulic pressure supply device 31, the directional control valve 36 is moved to the right position based on a command signal from the electronic control device 37. That is, a command signal is applied to the valve 36 according to the injection timing and injection period with respect to the current engine operating state, and the working pressure is applied to the working pressure supply passage 11 of the fuel injection valve 1 at the right position.
The first pressure receiving surface 10a of the piston 10 faces through the
It is supplied to the first chamber 9a of the cylinder chamber 9. When the resultant force of this working oil pressure and the fuel pressure applied to the needle valve 5 overcomes the resultant force of the fuel pressure in the second chamber 15b and the set load of the spring 12, the control piston 10 lifts and the fuel pressure and the working oil pressure are combined. The differential pressure causes the needle valve 5 to lift and leave the valve seat 6, and fuel is injected into the cylinder from the injection port 4.

Next, the electronic control device 3 of the hydraulic pressure supply device 31
When the solenoid valve 36 is switched to the left position based on the command signal 7, the supply of hydraulic pressure to the first chamber 9a is cut off and the hydraulic pressure in the same chamber is released. It is lowered by the fuel pressure in the chamber 15b and the biasing force of the spring 12. Following this downward movement, the needle valve 5 is seated on the valve seat 6, closing the injection port 4 and stopping fuel injection.

FIG. 4 is a graph showing the interrelationship between the injection pressure supply period, the working oil pressure supply period, and the fuel injection period. As is clear from this FIG. 4, the fuel injection timing and period are It depends on the timing and period, and the former can be freely controlled within the range of the fuel pressure supply period by appropriately selecting the latter. Moreover, since the supply pressure of the hydraulic oil has good rise and fall properties due to the above-described configuration, it is possible to improve the rise and fall properties of the fuel injection pressure, and improve the injection properties at the start and end of fuel injection. be able to.

5 to 7 show other embodiments of the present invention, and the difference from the previous embodiment is that the injection port closing operation of the needle valve is performed using the second hydraulic pressure supplied from the hydraulic pressure supply device. This is because it was designed to be carried out by

In FIG. 5, a third cylinder chamber 22 is located at a position adjacent to the rear end of the needle valve 5 in the first stage portion 2a of the main body 2 so as to surround the connecting portion 5b with the control piston 10 along the axis. A sleeve 23 is slidably fitted into the cylinder chamber 22 and is slidably fitted onto the connecting portion 5b. The first chamber 22a adjacent to the rear end of the needle valve 5 of the cylinder chamber 22 has a second chamber 22a which has one end communicating with the second electromagnetic directional control valve 36' of the hydraulic pressure supply device 31.
One end of the hydraulic pressure supply passage 24 is connected to the second chamber 22b located on the opposite side of the needle valve 5 with respect to the sleeve 23 in the cylinder chamber 22, and the first chamber 22b located on the needle valve 5 side of the control piston 10. It communicates with the first chamber 9a of the cylinder chamber 9. Said sleeve 2
3 completely blocks off the first chamber 22a and second chamber 22b of the third cylinder chamber 22.

In addition, in FIG. 6, the operating hydraulic pressure supply device 31
The two electromagnetic directional control valves 36' are the electromagnetic directional control valves 36'.
and is provided in parallel on the hydraulic circuit, and this second
The supply passage 39' connected to the outlet port 36'c of the electromagnetic directional control valve 36' is connected to the second working pressure supply passage 2.
Connected to 4. This second electromagnetic directional control valve 3
6' is also switchable and controllable by an electronic control device 37, and upon receiving a command signal from the control device 37 regarding the fuel injection end timing, the hydraulic pressure is changed to the passage 24.
It is now being supplied to

The operation of the fuel injection valve according to this embodiment up to fuel injection is almost the same as in the previous embodiment. Following the lift operation of the needle valve 5 during the fuel injection operation, the sleeve 23 moves upward within the third cylinder chamber 22 and comes into contact with the rear end wall of the third cylinder chamber 22. By the way, the second chamber 22b of the third cylinder chamber 22 is
Because it communicates with the first chamber 9a of the cylinder chamber 9,
Although the hydraulic pressure in the downward or closing direction acts on the needle valve 5 through the sleeve 23, the pressure receiving surface 1 of the control piston 10 is larger than the pressure receiving area of the needle valve 5 facing into the chamber 22a.
Since the pressure receiving area 0a is set to be sufficiently large, the control piston 10 lifts against the spring force and fuel pressure at the other end (not shown) (same configuration as in FIG. 1), and the needle valve 5 is moved by the fuel pressure. It lifts following the control piston 10.

Next, in the hydraulic pressure supply device 31, the second electromagnetic directional valve 36' is displaced to the right position based on the command signal from the control device 37 (at this time, the first electromagnetic directional valve 36 is displaced to the left position). ), the working oil pressure is supplied to the first chamber 22a of the third cylinder 22 through the second working oil pressure supply passage 24 at the final injection timing corresponding to the current engine operating state. This hydraulic pressure is applied to the pressure-receiving surface at the rear end of the needle valve 5 that is in contact with the sleeve 23, lowering the needle valve 5 to seat it on the valve seat 6, closing the injection port 4, and stopping fuel injection. Thereafter, in order to perform an injection operation, the first electromagnetic directional switching valve 36 is displaced in the hydraulic pressure supply direction, and at the same time, the second electromagnetic directional switching valve 36' is switched to the left position, and the second hydraulic pressure is released.

Note that the fuel pressure supply period and the first
a working hydraulic pressure supply period, a second working hydraulic pressure supply period,
The correlation with the fuel injection period is as shown in the graph of FIG.
It is understood that this depends on the timing of hydraulic pressure supply.

As explained above, in the injection valve of the present invention, the control of the injection timing and the injection period does not depend on the increase or decrease of fuel pressure, that is, the supply/cutoff, but the hydraulic pressure is controlled in advance according to the operating state of the engine. Since the injection timing and injection period are determined according to the following, the following effects can be obtained.

(1) Injection timing and injection period can be freely controlled;
It is possible to ensure the optimal injection timing and injection period for the operating condition of the engine.

(2) Fuel pressure is supplied before and after the needle valve to balance the biasing force acting on the needle valve, so the set load of the spring that presses the needle valve in the valve closing direction and the force required to operate the needle valve are The hydraulic pressure may be relatively low. Therefore, by increasing the supplied fuel pressure, high-pressure fuel injection can be realized, and the high-pressure injection can promote atomization of the atomized fuel.

(3) Since the biasing force of the spring or the biasing force of the spring and the second hydraulic pressure can be kept acting on the needle valve during the valve closing period, it is not necessary to keep fuel pressure always acting in order to close the valve. .

(4) A sharp fuel injection pressure waveform can be obtained, and excellent exhaust characteristics can be obtained.

(5) From the above (1), it is possible to meet the diversification of fuel properties required for diesel engines for ocean-going ships, and from the above (2), it is possible to respond to the diversification of fuel properties such as heavy oil, inferior quality, etc. can be dealt with.

[Brief explanation of the drawing]

Figures 1 to 4 show an embodiment of the present invention, in which Figure 1 is a longitudinal sectional view, Figure 2 is a partial vertical sectional view at a different phase from Figure 1, and Figure 3 is a hydraulic pressure A circuit diagram showing an example of a supply device, FIG. 4 is a graph showing operating characteristics, FIGS. 5 to 7 show other embodiments of the present invention, and FIG. 5 is a partially omitted longitudinal sectional view. FIG. 6 is a circuit diagram showing an example of an operating hydraulic pressure supply device, and FIG. 7 is a graph showing operating characteristics. DESCRIPTION OF SYMBOLS 1... Fuel injection valve, 2... Main body, 3... Nozzle nut, 4... Injection port, 5... Needle valve, 6... Valve seat, 7... Fuel chamber, 8... Fuel supply passage, 9... …
First cylinder chamber, 10... Control piston, 11...
...Operating oil pressure supply passage, 12...Spring, 13...Spring holder, 14...Vent hole, 15...Second cylinder chamber, 16...Pressure piston, 17...Branch path, 18...Rod, 20...magnetic material, 21...
Coil, 22... Third cylinder chamber, 23... Sleeve, 24... Second working hydraulic pressure supply path, 31... Working hydraulic pressure supply device, 33... Hydraulic pump, 36,3
6′...Electromagnetic directional control valve, 37...Electronic control device.

Claims (1)

[Scope of Claims] 1. A main body having an injection port at its tip and a fuel supply passage communicating with the injection port, and a needle valve slidably provided within the main body to open and close the injection port. In the fuel injection valve, the fuel injection valve is configured to guide pressurized fuel to the pressure receiving surface at the injection port side end of the needle valve through the fuel supply passage, and the fuel injection valve is configured to lead pressurized fuel to the pressure receiving surface at the injection port side end of the needle valve in the main body, on the opposite injection port side of the needle valve in the main body. A control piston and a pressure piston are integrally connected to a needle valve, and a pressure receiving surface formed at an end of the pressure piston opposite to the needle valve is pressurized via a branch passage communicating with the fuel supply passage. The fuel is guided, and the hydraulic fluid is guided through a hydraulic pressure supply passage that communicates with a hydraulic pressure supply device to a pressure receiving surface formed at the needle valve side end of the control piston, and a counter needle valve of the control piston. The pressure receiving surface formed on the side end is provided with a means for applying a biasing force toward the needle valve toward the control piston, and furthermore, the hydraulic pressure supply device is provided with a means for applying a biasing force in the direction of the needle valve to the control piston. A fuel injection valve characterized in that a working hydraulic pressure is supplied to the working hydraulic pressure supply passage based on a set injection timing and injection period. 2. The fuel injection valve according to claim 1, wherein the means for applying a biasing force in the direction of the needle valve to the control piston is a spring. 3 The means for applying a biasing force in the direction of the needle valve to the control piston is a spring, and a second means is arranged to guide hydraulic oil to a pressure receiving surface formed at the end of the needle valve opposite to the injection port. The fuel injection valve according to claim 1, which is an operating pressure supply passage.