JPH04287866A - Accumulator type fuel injection device - Google Patents

Abstract

PURPOSE:To prevent the fluctuation of injection quantity and injection timing in the injector of other cylinders by keeping reflected waves generated by the action of the injector of one cylinder from being propagated to other cylinders. CONSTITUTION:This accumulator type fuel injection device is provided with a common rail 38 for performing the pressure accumulation of high pressure fuel, an injection pipe 37 for leading fuel out of this common rail 38, an injector 36 provided cylinder by cylinder so as to receive fuel supply and to inject fuel to a diesel engine while being controlled electrically, and a check valve 62 for allowing the supply of fuel in the common rail 38 only to the injector 36 and regulating pressure propagation from the injector to the common rail 38.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention utilizes a pressure accumulator pipe (hereinafter referred to as a common rail) which is a type of surge tank for high-pressure fuel.
The present invention relates to a pressure accumulation type fuel injection device that accumulates pressure in the air and injects the accumulated high pressure fuel into a diesel engine using an electrically controlled injector.

0002

[Prior Art] Conventionally, high-pressure fuel is fed under pressure to a common rail by a high-pressure supply pump, and the pressure is accumulated.
A pressure accumulator fuel injection device is known that injects this common rail high-pressure fuel into a diesel engine using an electrically controlled injector.

0003

[Problems to be Solved by the Invention] However, in this configuration, the high pressure fuel stored in the common rail is extremely high at 150 MPa, so the reflected waves generated by the injector of one cylinder are transmitted to other cylinders via the common rail. There is a problem in that the fuel is propagated to the cylinder, affecting the opening and closing timing of the injector of that cylinder, and causing variations in the injection amount and injection timing.

[0004] Therefore, the present invention prevents the reflected waves generated by the operation of the injector of one cylinder from propagating to other cylinders, thereby reducing the variation in injection amount and injection timing among the injectors of other cylinders. The purpose is to prevent.

[0005]

[Means for Solving the Problems] In order to achieve the above object, the present invention includes a common rail for accumulating high-pressure fuel, a fuel pipe for deriving high-pressure fuel from the common rail, and a fuel pipe provided for each cylinder. an injector that receives fuel from the injector and electrically controls the injector to inject fuel into the diesel engine; The pressure accumulation type fuel injection device is characterized in that it is provided with a check member that allows and restricts pressure propagation from the injector to the common rail.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment embodying the present invention will be described below with reference to the drawings. FIG. 2 shows the overall configuration of the diesel engine-like fuel injection system of this embodiment, and FIG. 3 shows an injector provided for each combustion chamber of each cylinder of the engine.

In FIG. 3, the lower casing member 1 consists of a body lower 2, a connecting portion 3, and a valve casing 4.
Each member 2, 3, 4 is integrated by a retaining ring 5. A valve element sliding hole 6 and a fuel reservoir chamber 7 are formed in the valve casing 4, and the fuel reservoir chamber 7 is formed at the tip.
A nozzle hole 8 communicating with is formed. A large diameter portion 10 of a nozzle needle 9 is slidably fitted into the valve body sliding hole 6. A connecting portion 11 is formed on the large diameter portion 10 of the nozzle needle 9, and a small diameter portion 12 and a valve body portion 13 are integrally formed on the lower tip portion. and,
The seat part X is opened and closed by this valve body part 13, and the nozzle hole 8
injection is turned on and off.

At the tip of the connecting portion 11 of the nozzle needle 9, a flange 14, a piston pin 15 and a piston 1 are provided.
6 are integrally connected. Further, the nozzle needle 9 is urged in the closing direction by a spring 17. The piston 16 is slidably fitted into a cylinder 18 formed in the pod lower 2, and a pressure control chamber 19 is formed within the cylinder 18 from which the end of the piston 16 is exposed.

A plate valve 20 having an orifice is provided above the pressure control chamber 19, and a spring 21 for pressing the plate valve 20 is provided. An upper casing member 23 having a three-way control valve 22 (electromagnetic valve) is closely connected to the body lower 2 . That is, a cylindrical body upper 24 is screwed onto the body lower 2, a three-way valve body 25 is disposed in an internal hole of the body upper 24, and a retaining nut 26 is screwed into the internal hole of the body upper 24.

[0010] An outer valve 2 is disposed within the three-way valve body 25.
7 is slidably fitted into the outer valve 27, and an inner valve 28 is disposed in the inner hole of the outer valve 27. When the coil 29 is demagnetized, the outer valve 27 is in the lower position due to the force of the spring 30, and the high pressure side passage 31 and the pressure control chamber 19 are communicated via the oil passage 32. Further, when the coil 29 is excited, the outer valve 27 is in its upper position, and the pressure control chamber 19 and the drain passage (low pressure side passage) 33 are communicated via the oil passage 32.

A fuel supply passage 34 is formed in the lower casing member 1, one end of which is exposed on the surface of the casing member (body lower 2) 1, the other end communicates with the fuel reservoir chamber 7, and the upper The high pressure side passage 31 of the casing member 23 is connected to the high pressure side passage 31 of the casing member 23 . Further, an inlet 35 is screwed into the surface of the lower casing member (body lower 2) 1 and communicates with the fuel supply passage 34.

High-pressure fuel from a common rail 38, which will be described later, is supplied to the fuel reservoir chamber 7 through the inlet 35 and fuel supply passage 34, and is also supplied to the three-way control valve 22. Further, the fuel in the drain passage 33 can be drained into a drain tank. Therefore, when high-pressure fuel is supplied to the pressure control chamber 19, the force applied from the piston 16 in the valve closing direction to the nozzle needle 9 in response to this pressure is the force applied in the valve opening direction due to the pressure in the fuel reservoir chamber 7. The nozzle needle 9 closes the nozzle hole 8 by exceeding . From this state, the three-way control valve 22
is controlled and the pressure control chamber 19 is connected to the drain passage 33 on the low pressure side.
When the fuel in the pressure control chamber 19 flows out to the low pressure side, the nozzle needle 9 moves in the valve opening direction and fuel is injected. At this time, the hydraulic pressure slowly drops due to the action of the orifice of the plate valve 20.

As shown in FIG. 2, such an injector 36 for each cylinder is connected via an injection pipe 37 to a high-pressure accumulation pipe common to each cylinder, a so-called common rail 38. A high pressure supply pump 41 is connected to this common rail 38 via a supply pipe 39 and a check valve 40. This high-pressure supply pump 41 boosts the pressure of fuel sucked from the fuel tank 42 via the low-pressure supply pump 43 to a high pressure, and controls the pressure to a predetermined high pressure. That is, the cam 45 rotates periodically with the rotation of the engine 44, and the piston 47 in the cylinder 46 moves forward, so that the fuel from the low-pressure supply pump 43 is pressurized and supplied to the common rail 38. Further, the high pressure supply pump 41 is equipped with a discharge amount control solenoid valve 48 in order to always control the common rail pressure to a predetermined pressure.

[0014] Electronic control unit (hereinafter referred to as ECU)
Reference numeral 49 receives information on the rotation speed and load from the cylinder discrimination sensor 50, crank angle sensor 51, and load sensor 52, and determines the optimal injection timing and injection amount (injection amount) according to the engine condition determined from these signals. The ECU 49 outputs a control signal to the three-way control valve 22 so that the timing is reached.

Furthermore, a pressure sensor (not shown) for detecting common rail pressure is disposed on the common rail 38, and the ECU
49 controls the discharge amount so that the signal from this sensor becomes an optimal value set in advance according to the load and rotation speed. That is, negative feedback control of pressure is performed to perform more precise pressure setting.

In the common rail 38, the injection pipe 37
A check valve 62 is provided at the connection portion with. That is, as shown in FIG. 1, a valve body storage chamber 65 is formed in the common rail 38 so as to communicate with the internal passage 38a of the common rail 38. The valve body storage chamber 65 includes a plunger valve 66 and a spring 67 that allow only the flow of fuel from the common rail 38 to the injection pipe 37 and block the flow of fuel from the injection pipe 37 to the common rail 38. A check valve 62 and a seat member 68 having a seat seat 69 on which the plunger valve 66 is attached and detached are provided, and when the fuel joint 70 connected to the injection pipe 37 is screwed into the common rail 38, the seat member 68 is opened. fixed, and the spring 67 is held.

The plunger valve 66 is connected to the injection pipe 37.
It has a function of sucking back the fuel pressure to the common rail 38 by seating. The set load of the spring 67 of the check valve 62 is set to be smaller than the product of the common rail internal pressure minimum value Pmin and the pressure receiving area A1 of the plunger valve 66 (=Pmin・A1), and the plunger valve 66 is lifted by the common rail internal pressure. During operation, fuel passes through it. Further, the maximum load of the spring 67 is set to be larger than the product of the common rail internal pressure maximum value Pmax and the pressure receiving area A1 of the plunger valve 66 (=Pmax·A1).

When the fuel injection by the injector 36 is completed and a reflected wave is generated in the injection pipe 37 from the injector 36 side to the common rail 38 side, the plunger valve 67 is closed and the reflected wave is transferred to the common rail 38 as shown in FIG. Internal propagation is prevented. This results in
Interference between cylinders (pressure change in the common rail) that causes variations in injection timing and injection amount can be prevented.

Furthermore, since the check valve 63 can be installed in the common rail 38 in advance, it is extremely easy to connect it to the injector 36 via the injection pipe 37 when the engine is installed, and its workability is greatly improved. .

As described above, according to this embodiment, fuel is allowed to be supplied from the common rail 38 to the injector 36 at the connection part with the injection pipe 37 within the common rail 38, and fuel is allowed to be supplied from the injector 36 to the common rail 38. A check valve 62 (check member) that regulates pressure propagation is provided, and a check valve 62 (check member) is provided to restrict pressure propagation, and the common rail 3
The reflected wave toward the 8 side is regulated by a check valve 62. As a result, it is possible to prevent interference between cylinders due to reflected waves that cause variations in injection timing and injection amount over the entire rotational speed range of the internal combustion engine. Further, since the check valve 62 can be pre-assembled into the common rail 38, work efficiency when mounting the engine is greatly improved.

[0021]

[Effects of the Invention] As explained above, according to the present invention, in the common rail, fuel is allowed to be supplied from the common rail to the injector at the connection part with the fuel pipe, and pressure propagation from the injector to the common rail is restricted. By providing a check valve, it is possible to control reflected waves from the injector to the common rail that occur when fuel is injected by the injector, and as a result, interference between cylinders due to reflected waves that causes variations in injection timing and injection amount is completely eliminated. This can be prevented over the rotational speed range of internal combustion engines, and the check valve can be installed in the common rail in advance.
Workability when installing an engine is greatly improved.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing characteristic parts in an embodiment of the present invention.

FIG. 2 is a diagram showing the overall configuration of an embodiment of the present invention.

FIG. 3 is a sectional view showing an injector according to an embodiment of the present invention.

[Explanation of symbols]

36 Injector 37 Injection pipe 38 Common rail 62 Check valve

Claims (1)

[Claims] [Claim 1] A common rail that accumulates high-pressure fuel;
A fuel pipe that derives high-pressure fuel from this common rail,
an injector that is provided for each cylinder, receives fuel from the fuel pipe, and is electrically controlled to inject fuel into the diesel engine; 1. A pressure accumulation type fuel injection device, comprising: a check member that only allows fuel to be supplied from the common rail to the injector and restricts pressure propagation from the injector to the common rail.