JPS6196170A - Selector valve device - Google Patents

Abstract

PURPOSE:To enable a device to continually perform its correct switching, by constituting the selector valve device, which controls supply of pressure oil to a fuel booster, so that a valve unit of the device is opened and closed by adapting a plunger suitably at its lift position, in the case of a fuel injection device having the fuel booster. CONSTITUTION:A fuel injection device supplies pressure oil, fed from a pressure oil supply source, to a fuel booster through a fuel injection selector device 11, here the fuel oil, after its pressure is suitably increased, is supplied to the fuel injection device. The selector device 11 is constituted by the first and the second selector valve device 40, 41. Here the selector valve device 40 (similarly for the device 41) is constituted by a valve part 42, containing a valve body 44 having a valve hole 45, and a driving part 43. The valve hole 45 forms a through hole 46 connected with the pressure oil supply source while a through hole 47 connected with the fuel booster, and each through hole 46, 47 is opened reciprocating by a cam shaft interlocking to rotation of an engine, is adapted suitably in a lift position.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a fuel injection device for a diesel engine, and particularly to a fuel injection device that is provided with a fuel pressure booster to pressurize fuel and supply it to a fuel injection nozzle. The present invention relates to a switching valve device that controls the supply of pressure oil to the fuel pressure booster.

(Conventional example) Conventionally, this type of fuel injection device has been disclosed in, for example, Japanese Patent Application Laid-Open No.
As shown in Japanese Patent No. 48265, the supply control of hydraulic oil to the large-diameter piston chamber 13 of the fuel booster 9 is performed using two switching valve devices, an injection period control section 31 and a residual pressure control section 32, instead of using a general switching valve. I'm doing it more. That is, the injection period control section 3
The first pressure generating device [40] controls the first on-off valve 34 through the pressure oil generated in the large-diameter piston chamber 1 for hydraulic oil.
3 to control the injection timing, the residual pressure control unit 32 drives the second pressure generator 67 after the injection is completed, controls the second on-off valve 62, and controls the large-diameter piston chamber. This is to remove the residual pressure inside 13.

(Problems to be Solved by the Invention) In such a switching valve device for controlling the injection amount, the plunger chamber 39 of the injection period control section 31 and the residual pressure control section 3
Air dissolved in the working pond gradually accumulates in the second plunger chamber 68, and this accumulated air makes the switching operations of the first on-off valve 34 and the second on-off valve 62 unstable, resulting in a decrease in the injection amount. Control was also unstable.

Therefore, it is an object of the present invention to provide a switching valve device for accurately supplying hydraulic oil for driving a fuel pressure booster.

(Means for Solving the Problems) The gist of the present invention is that two through holes are formed in a valve hole at an appropriate distance, and a valve body is disposed in the valve hole to control communication between the two through holes. At the same time, a reciprocating plunger contacts the valve body at an appropriate lift position to open and close the valve body.

(Function) Therefore, since the opening and closing control is performed by directly pressing the valve body that controls the opening and closing of the two through holes with the plunger, it is not adversely affected by air unlike when pressure oil is used, and is accurate. This allows easy switching and achieves the above objective.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, a configuration diagram of a fuel injection device is shown, and a pressure supply source 1 includes a hydraulic oil tank 2 in which general hydraulic oil is stored, an oil feed pump 4 driven by an engine 3, and a relief valve 5. Pressure oil having a constant pressure is passed through a high-pressure oil supply line 6, reduced to a desired pressure via a pressure reducing valve 7, and stored in an accumulator 8. The pressure oil stored in the accumulator 8 is transferred to the pressure supply chamber 15 of the fuel booster 12 via the fuel injection switching device 11 described below.
sent within.

Further, the pressure oil whose pressure has been appropriately reduced by the pressure reducing valve 10 is transferred to a pressure chamber 34 of a fuel injection nozzle 30 as described below via a branch passage 9.
has been added to.

The fuel pressure booster 12 has a large diameter bore 13a and a small diameter bore 13.
The bores 13a and 13b are formed vertically in communication with the bores 13a and 13b.
A servo piston 14 consisting of a large-diameter piston 14a and a small-diameter piston 14b is arranged within the servo piston 14 corresponding to the diameter, and a pressure supply chamber 15 is provided in the upper part, and the pressure supply chamber 15 is used for the above-described fuel injection. Switching device No. 11 is connected.

A compression chamber 16 is provided below the small-diameter piston 14b of the servo piston 14 through a fitting bore 13b. The fuel injection nozzle 30 is connected to the fuel injection nozzle 30.

The fuel supply device 20 includes a plunger 22 having a lead 21.
moves up and down within the cylinder 23 to suck fuel from the fuel tank 24, compress the fuel, and forcefully feed it into the compression chamber 16. The control force from is transmitted via the link mechanism 26 to rotate the plunger 22 as appropriate to control the supply amount. That is, by controlling this supply amount, the injection amount is controlled.

The vertical movement of the plunger 22 is performed by engine rotation transmitted from a cam 29 via a timer 27 and a camshaft 28 . Note that this fuel supply device supplies fuel into the compression chamber 16 before the fuel boosting chamber 12 is activated.

The fuel injection nozzle 30 has a configuration generally called an automatic valve, and includes a main body 31 and a needle valve 3 disposed inside the main body 31.
2, a spring 33 that biases the needle valve 32 in the closing direction, and a pressure chamber 34 that guides the pressure oil that biases the spring 33 in the direction of suppression.
Pressure oil at a desired pressure is supplied via a pressure reducing valve 10.

In this fuel injection nozzle 30, fuel whose pressure has been increased by the fuel pressure intensifier 12 is supplied to the fuel reservoir 35, and the pressure applied to the pressure stage 36 of the needle valve 32 is added to the sum of the pressures in the spring 33 and the pressure chamber 34. When the force is overcome, the needle valve 32 is lifted against the spring 33 and the pressure, the nozzle hole 37 is opened, fuel is injected from the nozzle hole 37, and the needle valve 32 is closed as the pressure decreases.

In FIG. 2, a switching device 11 for fuel injection is shown.

It consists of first and second switching valve devices 40 and 41 according to the present invention, and although their operational purposes are different, they are structurally exactly the same.

First, the first switching valve device 40 consists of a valve part 42 and its driving part 43, and the valve part 42 has a valve hole 45 formed in a main body 44, and is opened to the valve hole 45 and separated by an appropriate distance. Two through holes 46 and 47 are formed in the middle. The through hole 46 is connected to the pressure supply source 1 via the high pressure oil supply passage 6, and the through hole 47
is connected to the pressure supply chamber 15 of the fuel pressure booster 12 via the high pressure oil feed passage 6.

A valve body 48 is disposed within the valve hole 45, and the valve body 48 is urged by a spring 49 and is seated on a valve seat 50. When seated, communication between the through holes 46 and 47 is cut off.

The valve body 48 is composed of a valve 48a and a piston 48b, and the front and rear portions of the valve 48a are formed to have approximately the same diameter, and have approximately the same pressure receiving area. The piston 48b is arranged in the valve hole 45 in an oil-tight manner. Note that the valve body 48 is provided with a position detection sensor 52 via a rod 51.

The drive unit 43 is made up of a plunger 54 that expands and contracts within a sliding hole 53 that communicates with the valve hole 45, a tappet 55 that is fixed to the lower end of the plunger 54, and a spring 56 that presses the respective tappet 55. 55 is in contact with the cam 57 formed on the camshaft 28 shown in FIG.
expands and contracts against the spring 56, contacts the valve body 48 at an appropriate lift position in the upward stroke, lifts the valve body 48 against the spring 49, and opens to communicate with the first through holes 46 and 47. As a result, the pressure oil flows from the through hole 46 to the through hole 47 and is sent to the fuel pressure booster 12. The opening time of the valve body 48 is determined by the plunger 5.
4 is the time during which the plunger 54 is in contact, and the time is controlled by the short separation S between the tip of the plunger 54 and the piston 48a of the valve body 48 at the bottom dead center position of the plunger 54, and the contact of the plunger 54 is ensured. When discussed, the valve body 48 is the same as the valve body 4.
8 is seated on the valve seat 50 and closed. That is, the relationship between the plunger 54 and the valve body 48 appears as shown in the characteristic diagram in FIG. Therefore, the contact period becomes the injection period. The opening time of the valve body 48 can be appropriately controlled by controlling the distance aiS.

The second switching valve device 41 has exactly the same structure as the first switching valve device 40, and includes a valve portion 62 and a driving portion 63 thereof.
The valve part 62 has a valve hole 65 formed in the main body 64, and is connected to a zero through hole 66 which opens into this valve hole 65 and has two through holes 66 and 67 formed at an appropriate distance. The return passage 61 is.

It is connected to the high-pressure oil feed passage 6 between the fuel pressure booster 12 and the through hole 47 of the valve portion 42 of the first switching valve device 40 . Further, the first through hole 67 is connected to a return passage 61 connected to the tank 2.

A valve body 68 is disposed within the valve hole 65, and the valve body 68 is biased by a spring 69 and is seated on a valve seat 70. When seated, communication between the through holes 66 and 67 is cut off.

The valve body 68 consists of a valve 68a and a piston 68b, and the front and rear portions of the valve 68a are formed to have approximately the same diameter.

They have approximately the same pressure receiving area. The piston 68b is
It is arranged in the valve hole 65 in an oil-tight manner. In addition.

A 'sensor 72 for position detection is provided on the valve body 68 via a rod 71.

The drive unit 63 includes a plunger 74 that extends and contracts within a sliding hole 73 communicating with the valve hole 65, a tappet 75 fixed to the lower end of the plunger 74, and a spring 76 that presses the tappet 75. is in contact with a cam 77 formed on the camshaft 28 shown in FIG.
4 expands and contracts against the spring 76 and comes into contact with the valve body 68 at an appropriate lift position in the upward stroke, thereby lifting the valve body 68 against the spring 69 and opening the valve body 68 to communicate with the first through holes 66 and 67.

As a result, the pressure oil in the pressure supply chamber 15 of the fuel booster 12 and the high pressure oil feed passage 6 is returned to the tank 2 via the return passage 61. The open time of the valve body 6B is the time during which the plunger 74 is in contact with it, and when the contact of the plunger 47 is released, the valve body 68 is seated on the valve seat 70 and closed.

An example of this effect will be explained in the above configuration.

First, when the engine 3 is rotated by the starter and started, pressure oil with a constant pressure is sent into the high-pressure oil passage 6 by the oil feed pump 4 of the pressure supply source 1. There is. Furthermore, since the camshaft 28 is also being rotated at the same time, fuel oil is guided from the fuel tank 24 from the fuel supply device 20 and delivered to the compression chamber 16 of the fuel booster 12.

The switching device 11 for fuel injection is also driven by the rotation of the camshaft 28, and the first switching valve device 40 is first driven by the cam 57 having a fast phase. That is.

The tappet 55 is displaced by the cam 57 against the spring 56, the plunger 54 is lifted, and at an appropriate position during the lift, its tip abuts against the lower end of the piston 48b of the valve body 48 and presses the valve body. The body 48 is lifted and opened against the spring 49, and is in communication with the through holes 46 and 47, so that the pressurized oil is delivered to the fuel pressure intensifier 12 via the high pressure oil supply passage 6.
into the pressure supply chamber 15. Therefore, the servo piston 14 is displaced downward, and the fuel supplied from the fuel supply chamber 20 is compressed in advance into the compression chamber 14, and is sent to the fuel injection nozzle 30, lifts the needle valve 32, and injects the fuel. Fuel is injected from the hole 37. This fuel injection period is controlled by the first switching valve device [40], and continues until the plunger 54 strokes downward and the contact is released. is seated on the valve seat 50, and pressure feeding of pressure oil to the fuel pressure booster 12 is stopped.

As a result, the pressure supplied to the fuel injection nozzle 30 also decreases, and the injection ends. Then, cam 7 with the next delayed phase
7, the plunger 74 of the second switching valve device 41 is lifted. Therefore, the valve body 68 is lifted open,
Since the return passage 61 is opened, the pressure oil in the pressure supply chamber 15 of the fuel pressure booster 12 is returned to the tank 2, and the pressure oil in the pressure supply chamber 15 of the fuel pressure booster 12 is returned to the tank 2.
The pressure oil inside will decrease. Then, the servo piston 14 is easily returned by the fuel supplied into the compression chamber 16 to prepare for the primary injection.

(Effect of the invention)
As described above, according to the present invention, the valve body is not opened via pressure oil as in the conventional case, but is opened by bringing the plunger into direct contact at an appropriate position, so that the intervention of pressure oil is not required. In addition, the injection period can be arbitrarily selected by appropriately determining the distance S between the plunger and the valve body, and a short injection period can be determined. It is also possible.

Furthermore, since the pressure receiving area before and after the valve body is almost the same,
The driving torque only needs to be against the spring, and can be made very small.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of a fuel injection device incorporating the switching valve device of this invention, Fig. 2 is a sectional view of a switching device using two switching valve devices of this invention for different purposes, and Fig. 3 is a characteristic diagram of the first switching valve device. 40.41...Switching valve device, 42,62...Valve part,
43.63... Drive unit, 45, 65... Valve hole, 46
．． 47...through hole, 48. f38... Valve body, 54.7
4 pa... plunger. Figure 2 Figure 3 Cam angle

Claims (3)

[Claims] 1. Two through holes are formed at an appropriate distance in the valve hole, and a valve body that controls communication between the two through holes is disposed in the valve hole, and a plunger that reciprocates this valve body is provided with an appropriate lift. A switching valve device characterized in that the switching valve device is configured to open and close by contacting each other at certain positions. 2. 2. The switching valve device according to claim 1, wherein the valve body has substantially equal pressure receiving areas before and after the seat portion. 3. 2. The switching valve device according to claim 1, wherein the valve body is provided with a sensor for position detection.