JPH0849617A - Solenoid valve device of fuel injection pump - Google Patents

Abstract

PURPOSE:To improve responsiveness at the time of closing a solenoid valve device suitably used as an electromagnetic spill valve for controlling the fuel, in a fuel supply passage for a diesel engine. CONSTITUTION:A spill passage consisting of an entrance passage 11 and an exit passage 13 formed in a body 1, a solenoid 2 for generating electromagnetic force, and a valve body formed of a needle valve 4 for opening/closing the spill passages 11, 13 and an armature 6 which displaces the needle valve 4 by the electromagnetic force of the solenoid 2, are provided, and arranged in a fuel injection pump equipped with a feed pump for pressurizing the fuel. An oil pressure chamber 8 so constituted that the pressurized fuel energizes the needle valve 4 in the valve closing direction by introducing the pressurized fuel from the feed pump, and a pressure introduction passage 16 for introducing the fuel pressurized by the feed pump to the oil pressure chamber 8 at the time when the fuel injection pump is in its intake stroke, are also provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solenoid valve device for a fuel injection pump, and more particularly to a solenoid valve device for a fuel injection pump suitable for use as an electromagnetic spill valve for controlling fuel in a fuel supply passage of a diesel engine.

[0002]

2. Description of the Related Art Conventionally, an electromagnetic spill valve for controlling fuel flow in a fuel supply passage of a diesel engine has been known. For example, Japanese Unexamined Patent Publication No. 64-45954 discloses a fuel injection pump configured by using such an electromagnetic spill valve.

The fuel injection pump described in the above publication is a so-called inner cam type distribution pump, and is configured to inject fuel into each cylinder of a diesel engine at a predetermined timing. This fuel injection pump
Roughly speaking, there are a low-pressure pump that supplies fuel to the pressurizing chamber, a high-pressure pump whose main part is a plunger that slides in the pressurizing chamber with a predetermined stroke, and an electromagnetic spill valve that connects or disconnects the pressurizing chamber and the low-pressure chamber. It is provided with a configuration.

In this case, the plunger is configured to make a stroke in the pressurizing chamber as the engine rotates.
Further, the pressurizing chamber communicates with fuel injection nozzles arranged in each cylinder of the engine at a predetermined timing. Therefore, assuming that the electromagnetic spill valve is closed, when the plunger strokes to reduce the volume of the pressurizing chamber,
As a result, the fuel in the pressurizing chamber is pressurized and supplied to the fuel injection nozzle, and fuel injection is performed.

On the other hand, when the electromagnetic spill valve is open, the pressure chamber communicates with the low pressure chamber through the electromagnetic spill valve even if the plunger strokes and the volume of the pressure chamber changes accordingly. Therefore, the internal pressure is not increased. Therefore, in this case, high-pressure fuel is not supplied to the fuel injection nozzle, and fuel injection is not executed.

That is, when the electromagnetic spill valve is used, it becomes possible to control the fuel injection timing independently of the operating cycle of the plunger which constitutes the high-pressure pump, and to realize highly accurate fuel injection timing control in the diesel engine. can do.

In this case, as the structure of such an electromagnetic spill valve, a spill passage consisting of a fuel inlet passage opening to the pressurizing chamber and a fuel outlet passage opening to the low pressure chamber is connected or cut off by a needle valve. A structure in which a valve spring for urging the needle valve in the valve opening direction and an electromagnetic solenoid for generating a reaction force against the valve spring are provided has been generally used.

[0008]

As described above, the electromagnetic spill valve is used to control the fuel injection timing, and therefore high responsiveness is required. In particular, as the number of cylinders of a diesel engine increases, higher responsiveness is required.

That is, comparing a fuel injection pump for 6 cylinders with a fuel injection pump for 4 cylinders, for example, the fuel injection pump for 6 cylinders is more efficient than the fuel injection pump for 4 cylinders. The working angle (usable range) is narrowed.

Therefore, in the case of the fuel injection pump for 6 cylinders, the period of each process of the diesel engine is only 60 ° in terms of the rotation angle of the pump shaft. Inhalation needs to be completed. However, if the response of the electromagnetic spill valve is poor,
It becomes impossible to suck all the predetermined amount of fuel into the cylinder.

Further, paying attention to the operating characteristics of the electromagnetic spill valve when it is opened and when it is closed, high-pressure spill fuel urges the valve element (needle valve) of the electromagnetic spill valve in the valve opening direction when the valve is opened. Therefore, the valve can be opened relatively responsively.
However, when the electromagnetic spill valve is opened, the high-pressure spill fuel acts in such a direction as to hinder the valve closing operation of the needle valve, which deteriorates the valve closing response.

As described above, in the conventional electromagnetic spill valve, the valve closing response is not sufficient, so that the feed pressure is released in the intake process, and there is a possibility that the injection amount may be insufficient due to defective filling of fuel. was there.

The present invention has been made in view of the above points, and the pressurized fuel generated in the fuel injection pump and the spill fuel flowing in the spill passage are closed when the valve body is closed. It is an object of the present invention to provide an electromagnetic valve device for a fuel injection pump that improves the response when the valve is closed by urging the solenoid valve device in the direction that the valve is closed.

[0014]

[Means for Solving the Problems] The above problems can be solved by taking the following measures.

According to the first aspect of the present invention, a spill passage having an inlet passage and an outlet passage formed in the body, a solenoid arranged in the body for generating an electromagnetic force, and the spill passage are opened and closed. For a fuel injection pump having a feed pump for pressurizing the fuel, and a valve body including a needle valve for operating the solenoid valve and an armature portion for displacing the needle valve by applying the electromagnetic force of the solenoid. In a solenoid valve device of an injection pump, when the pressurized fuel is introduced from the feed pump, the pressurized fuel urges the needle valve in a valve closing direction, and the fuel injection pump sucks the fuel. When in process,
A pressurized fuel introduction mechanism for introducing the fuel pressurized by the feed pump into the pressure chamber is provided.

Further, according to the invention of claim 2, a spill passage formed of an inlet passage and an outlet passage formed in the body,
A valve body including a solenoid disposed in the body for generating an electromagnetic force, a needle valve for opening and closing the spill passage, and an armature portion for displacing the needle valve by applying the electromagnetic force of the solenoid. And
In a solenoid valve device of a fuel injection pump arranged in a fuel injection pump having a feed pump for pressurizing fuel, a pressure chamber into which pressurized fuel for urging the needle valve in a valve closing direction is introduced, and this pressure chamber And a spill fuel introducing pipe that communicates the spill passage downstream from the opening / closing position of the spill passage with a needle valve, and introduces the spill fuel flowing in the spill passage into the pressure chamber as pressurized fuel, and the spill passage pressure of the spill passage. Spill passage pressure detecting means for detecting that the spill passage pressure has decreased to the vicinity of the feed pressure generated by the feed pump, and this spill passage pressure detecting means detects that the spill passage pressure has decreased to the vicinity of the feed pressure generated by the feed pump. When the solenoid valve is energized, valve driving means for energizing the solenoid and immediately driving the needle valve to close is provided.

[0017]

The above-mentioned means operate as follows.

According to the first aspect of the present invention, when the fuel injection pump is in the suction process, the fuel pressurized by the feed pump by the pressurized fuel introducing mechanism is introduced into the pressure chamber and introduced into this pressure chamber. Since the pressurized fuel urges the needle valve in the valve closing direction, the valve closing characteristic of the solenoid valve device can be improved. Further, the fuel injection pump is originally provided with a feed pump for its function, and the needle valve is urged to be closed by using the pressurized fuel pressurized by the feed pump. Also, the structure of the fuel injection pump does not become complicated.

The timing at which the needle valve closes is during the intake stroke of the cycle of the suction stroke, compression stroke, and discharge stroke carried out by the fuel injection pump, so the fuel injection pump is in the suction stroke. By sometimes introducing pressurized fuel into the pressure chamber, the closing operation of the needle valve can be easily synchronized with the cycle operation of the fuel injection pump.

According to the second aspect of the invention, there is provided a spill fuel introducing pipe having one end connected to the pressure chamber and the other end connected to the downstream side of the opening / closing position of the needle valve in the spill passage. The high pressure fuel (spill fuel) introduced into the pressure chamber from the spill passage closes the needle valve because the pressure fluid flowing through the spill passage at the time of valve opening can be introduced into the pressure chamber through the spill fuel introduction pipe. Energize in the valve direction. In the state immediately after the solenoid is energized and the needle valve closing operation is started, the spill passage is not completely closed by the needle valve, so that the spill fuel flowing through the spill passage is connected to the spill fuel introduction pipe. Is introduced into the pressure chamber via.

Therefore, in the state immediately after the closing operation of the needle valve is started, the needle valve is caused by both the magnetic force due to the excitation of the solenoid and the pressure of the high pressure fuel introduced from the spill passage into the pressure chamber. Since the valve closing operation is performed, the valve closing response of the solenoid valve device can be improved.

On the other hand, in the solenoid valve having the above structure,
For a while after the needle valve is opened, although the pressure in the spill passage (spill passage pressure) is lowered, a relatively large amount of fuel flows through the spill passage due to inertia. Therefore, in order to shut off the spill passage midway when a large amount of fuel is flowing, it is necessary to generate a large valve closing force in the solenoid, which requires a large amount of electric power.

For this reason, conventionally, the valve opening period is set so that the needle valve remains open for a predetermined period even if the spill passage pressure decreases.

However, if the valve opening period of the needle valve is set to be long as in the conventional case, this valve opening period overlaps with a part of the suction process, and the substantial suction process is shortened, especially in the multi-cylinder period. May cause inhalation failure.

According to the second aspect of the invention, however, spill passage pressure detecting means is provided for detecting that the spill passage pressure has dropped to near the feed pressure generated by the feed pump, and the spill passage pressure detecting means is used to detect the spill passage pressure. When it is detected that the pressure has dropped to near the feed pressure generated by the feed pump, the valve drive means energizes the solenoid to immediately drive the valve to close the needle valve. It is possible to prevent overlapping and improve the fuel inhalability.

Further, as described above, in the state immediately after the closing operation of the needle valve is started, the needle valve has a magnetic force due to the excitation of the solenoid and a pressure of the high pressure fuel introduced from the spill passage into the pressure chamber. Since the valve closing operation is performed by both forces, the valve closing response of the solenoid valve device is improved. Therefore, even if the needle valve is driven to close the valve immediately when the spill passage pressure decreases, it is not necessary to generate a large valve closing force in the solenoid, and the valve closing operation can be performed with a small amount of electric power.

[0027]

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows an electromagnetic valve device which is a first embodiment of the present invention. The solenoid valve device according to this embodiment is incorporated as a solenoid spill valve in a fuel injection pump of a diesel engine (diesel engine) shown in FIG. 2 (hereinafter, this solenoid valve device is referred to as a solenoid spill valve).
The solenoid valve device according to this embodiment corresponds to claim 1.

First, the overall structure of a fuel injection device (fuel injection pump) 40 in which an electromagnetic spill valve 20 according to an embodiment of the present invention is arranged will be described with reference to FIG. In the following description, a fuel injection pump applied to a 6-cylinder diesel engine will be described as an example.

The fuel injection pump 40 is an inner cam type distribution type fuel injection pump, and the fuel pumped from the fuel tank 41 to the pump low pressure side passage 55 by the feed pump 42 is passed through the pump high pressure side passage 56 to the fuel suction gallery (fuel low pressure chamber). ) 57, and by controlling the opening and closing of the electromagnetic spill valve 20 described later, high-pressure fuel whose injection timing and injection amount are adjusted is pressure-fed from the delivery valve 53 to the fuel injection valve 51 of the internal combustion engine (diesel engine). There is. Further, the pump low pressure side passage 55 and the pump high pressure side passage 5
A regulator 52 is provided between the regulator 52 and the pump 6, and the fuel pressure in the pump high pressure side passage 56 is kept constant.

Inside the fuel injection pump 40, a rotor 30 is rotatably fitted in a cylinder formed in the pump housing to switch the fuel passage, and the rotor 30.
A plunger 31 and the like which are slidably arranged to pressurize the fuel are arranged in a plunger chamber formed in No. 0.

Inside the cylinder, the fuel pressurized in the plunger chamber is supplied to the fuel injection valve 5 via the delivery valve 53.
1. The discharge passage 25 for pressure-feeding to No. 1, the first communication passage 21 for guiding the fuel pressurized in the plunger chamber to the electromagnetic spill valve 20 for adjusting the fuel injection amount, and the electromagnetic spill valve 20 being opened. A second communication passage 22 for allowing the fuel pressurized by the above to flow into the cam chamber 43 is provided. The cam chamber 43 is a space formed in the pump housing, and the plunger 31 of the rotor 30 is located inside the cam chamber 43. Further, the fuel flowing into the cam chamber 43 functions as lubricating oil for the sliding contact portion of the inner cam 45 and the like.

As shown in FIG. 1, the rotor 30 having the function of distributing fuel has a suction port 32 for sucking the fuel supplied to the plunger chamber, and a discharge passage 25 for discharging the high-pressure fuel pressurized in the plunger chamber. Discharge port 3 for discharging to
3, a spill port 34 for discharging fuel to the communication passage 22 for adjusting the amount of fuel injection, an annular groove 36 connected to this spill passage, and a predetermined angular interval (six cylinders connected to this annular groove 36). 60 ° for diesel engines
Notch 35 for valve closing assistance formed in each (FIG. 1 (B)).
Reference) is formed.

An annular inner cam 45 is in contact with the radially outer end surface of the plunger 31. The inner cam 45 has a cam mountain formed on the inner peripheral surface in the circumferential direction. When the rotor 30 is rotated by the drive shaft 44 connected to the diesel engine, the plunger 31 is attached to the cam mountain of the inner cam 45. It is energized and moves back and forth in the plunger chamber.

Further, in the above structure, the fuel intake gallery 57 and the intake port 32 communicate with each other in the fuel intake stroke in which the plunger 31 moves radially outward by the rotation of the rotor 30, and the fuel intake gallery 57 and the intake port 32 in the compression stroke. Are arranged to close. Further, the discharge port 33 of the rotor 30 is connected to the discharge passage 2 during the discharge stroke.
It is communicated with 5.

An electromagnetic spill valve 20 is arranged at a position downstream of the communication passage 21 with respect to the rotor 30. The electromagnetic spill valve 20 connects the rotor 30 to the communication passage 21 for introducing high-pressure fuel and the cam chamber 43. Communication passage 2 connected to
Communication with or disconnection from 2 is performed.

On the other hand, a pulsar 47 is arranged on the drive shaft 44 connected to the above-mentioned diesel engine, and a rotation speed sensor (N) is arranged so as to face the pulsar.
E sensor) 46 is provided. This NE sensor 46
The rotational speed signal detected by the fuel injection amount control device (hereinafter,
It is input to the ECU). This ECU is composed of a microcomputer, and has the NE sensor 4 described above.
6 and other various sensor signals, the operating state of the diesel engine is detected, the electromagnetic spill valve opening timing is calculated from this operating state, and the opening / closing control of the electromagnetic spill valve 20 is performed.

When the rotation of the diesel engine is transmitted to the rotor 30 via the drive shaft 44 as described above, the plunger 31 reciprocates in the radial direction along the cam profile of the inner cam 45, and the fuel intake gallery 57 is introduced into the plunger chamber. From the plunger chamber to the fuel injection valve 51 via the discharge passage 25, and the electromagnetic spill valve 20 overflows at the overflow timing (spill timing). Is adjusted, that is, the fuel injection amount is controlled.

In FIG. 2, reference numeral 48 is a timer device, which is composed of a timer piston 49, a timing control valve 50 and the like. This timer device 48 is an arm 4
It is connected to the inner cam 45 via 9a, and the inner cam 45 can be displaced over a predetermined amount by the operation of the timer piston 49. Further, the operation of the timer piston 49 is controlled by the opening / closing operation of the timing control valve 50 which is connected to the above-mentioned ECU and driven and controlled, whereby the advance angle or the retard angle is controlled.

Next, the structure of the electromagnetic spill valve 20 provided in the fuel injection pump 40 having the above structure will be described in detail.

As shown in FIG. 1, the electromagnetic spill valve 20 is roughly composed of a body 1, a solenoid 2, a return spring 3, a needle valve 4, an armature 6, and a seat member 9.
And the like.

The body is composed of a body 1 and a seat member 9, and a spill passage (hereinafter referred to as a fuel inlet) including a fuel inlet passage 11 and a fuel outlet passage 13 is provided inside the seat member 9 arranged at a lower portion. The passage 11 and the fuel outlet passage 13 are collectively referred to as a spill passage).

The fuel inlet passage 11 communicates with a plunger chamber for pressurizing the fuel via a communication passage 21, and is configured to supply the high pressure fuel pressurized in the plunger chamber. Further, the fuel outlet passage 13 is connected to the cam chamber 43 via the communication passage 22.

Further, the fuel inlet passage 11 and the fuel outlet passage 1
3 is configured so as to communicate with each other at a central lower position of the sheet member 9, and a body seat surface 12 is formed in this communicating portion. The body seat surface 12 is a portion that functions as a valve seat of the needle valve 4. Further, a needle guide surface 14 (having a cylindrical shape) that guides the vertical movement of the needle valve 4 by slidingly contacting a needle valve 4 described later is formed in the central portion of the seat member 9. ing.

On the other hand, the body 1 is liquid-tightly fixed to the upper portion of the sheet member 9, and the solenoid 2,
A needle valve 4, an armature 6 and the like are arranged.

The solenoid 2 is provided inside the body 1, and the upper end of the solenoid 2 is exposed in the armature chamber 7 formed in the upper portion of the body 1. The solenoid 2 is configured to be excited when a current is applied. Further, the solenoid 2 is a computer (hereinafter referred to as ECU) that performs a fuel injection control process (not shown).
The ECU is configured to be energized and controlled by this ECU.

The armature 6 is made of a magnetic metal and is movable in the body body 1 in the vertical direction in the figure. The armature 6 is composed of a disc-shaped portion 6a and a shaft portion 6b arranged on the upper portion. The disk-shaped portion 6 a is located in the armature chamber 7 arranged in the upper portion of the body body 1, and the lower surface thereof is configured to face the solenoid 2. The shaft portion 6b is movably supported on the armature guide surface 1a formed on the body body 1. The lower end of the shaft portion 6b is in contact with the upper end surface of the needle valve 4 described later. A return spring 5 composed of a coil spring is also interposed between the upper surface of the disc-shaped portion 6a and the ceiling portion of the armature chamber 7.

The needle valve 4 has a disc-shaped portion 4a formed on the upper portion thereof, and a valve portion 4b disposed on the lower portion of the disc-shaped portion 4a and liquid-tightly supported on the needle guide surface 14 so as to be vertically movable. It is composed of and. Diameter D _S of the disc-shaped portion 4a is set to be larger than the diameter D _N of the valve portion _{4b (D S> D N)} . Further, a return spring 3 composed of a coil spring is arranged below the disk-shaped portion 4a, and the needle valve 4 is always elastically biased upward by the elastic force of the return spring 3. Further, the lower end of the valve portion 4b has a seat member 9
And the lower end of the valve portion 4b comes into liquid-tight contact with the body seat surface 12 when the needle valve 4 moves downward, thereby closing the spill passages 11 and 13. To do.

A hydraulic chamber 8 (constituting a pressure chamber) is formed in the body body 1, and the disk-shaped portion 4a formed in the needle valve 4 moves in the hydraulic chamber 8 vertically and liquid-tightly. It is configured to do. A pressure introduction passage 16 and a pressure relief passage 17 are connected to the hydraulic chamber 8, respectively.
Both the pressure introduction passage 16 and the pressure relief passage 17 are formed continuously with the body 1 and the seat member 9, and the pressure introduction passage 16 is opened at the bottom surface of the seat member 9.
Further, the pressure relief passage 17 is opened on the side surface of the seat member 9.

In the opening of the pressure introducing passage 16, one end of the communication passage 23 is connected to the above-mentioned notch 35 for assisting valve closing.
The other end of the communication passage 24, one end of which is connected to the cam chamber 43, is connected to the opening of the pressure relief passage 17. Further, the pressure introduction passage 16 is provided with a first throttle 18 having a relatively large hole diameter, and the pressure relief passage 17 is provided with a second throttle 1 having a relatively small hole diameter.
9 are provided.

Therefore, when the notch 35 for assisting valve closing communicates with the communicating passage 23 as the rotor 30 rotates, the spill port 34 and the notch 3 for assisting valve closing are provided in the pressure introducing passage 16.
5. The fuel whose pressure is increased by the feed pump 42 is introduced through the communication passage 23. In addition, the valve closing assist notch 35
Is configured to be connected to the communication passage 23 connected to the pressure introduction passage 16 when the fuel injection pump 40 is in the suction process, that is, when the suction port 32 communicates with the fuel suction gallery 57.

As a result, when the fuel injection pump 40 is in the intake process, the fuel whose pressure has been boosted by the feed pump 42 (hereinafter referred to as assist fuel) is introduced into the plunger chamber, and the spill port 34, the annular groove 36, It is introduced into the hydraulic chamber 8 through the valve closing assist notch 35, the communication passage 23, and the pressure introduction passage 16. The assist fuel introduced into the hydraulic chamber 8 presses and urges the upper surface of the needle valve 4 downward.

The timing at which the solenoid 2 is energized by the ECU is also when the fuel injection pump 40 is in the intake process, and the timing at which the intake port 32 communicates with the fuel intake gallery 57 and the timing at which the solenoid 2 is energized are the same. It is configured to synchronize. Therefore, when the needle valve 4 closes, the needle valve 4 closes due to the pressure of the fuel introduced into the hydraulic chamber 8 in addition to the magnetic force generated by the excitation of the solenoid 2. It is possible to close the needle valve 4 well.

[0054] Further, the above-described manner the needle valve 4 is larger than the diameter D _N of the diameter D _S is the valve portion 4b of the disc-shaped portion 4a serving as a pressure receiving portion of the pressurized fuel, thus since the pressure receiving area wide, Even if the pressure of the fuel pressurized by the feed pump 42 per unit area is smaller than the pressure of the spill fuel, the oil pressure (assist force) that urges the needle valve 4 downward can be increased.

When the pressure in the hydraulic chamber 8 exceeds a predetermined value, the fuel in the hydraulic chamber 8 is relieved of pressure in the pressure release passages 17,
It is configured to be discharged to the cam chamber 43 via the communication passage 24. Further, the predetermined value can be determined by the diameter of each of the diaphragms 18 and 19.

The needle valve 4 is moved downward by being biased by the magnetic force generated in the solenoid 2 and the pressure of the assist fuel introduced into the hydraulic chamber 8 as described above, and the needle valve 4 causes the spill passages 11 and 13 to move. Is blocked. Therefore, the overflow (spill) of the high-pressure fuel pressurized in the plunger chamber to the cam chamber 43 through the fuel outlet passage 13 and the communication passage 22 is stopped, whereby the fuel is pumped from the fuel injection pump 40 to the diesel engine. Pumped.

As described above, the spill passages 11 and 1 in which a force acts in the valve opening direction due to the flow of high-pressure spill fuel.
Even if 3, the needle valve 4 resists the force in the valve opening direction.
Can be closed with good responsiveness. By improving the valve closing response of the needle valve 4 in this manner, it is possible to reliably prevent occurrence of insufficient injection amount due to defective filling due to feed pressure loss in the intake process of the diesel engine. The above matters are particularly effective in the above-described multi-cylinder engine having a small working angle.

On the other hand, when the energization of the solenoid 2 is stopped, the needle valve 4 is moved upward by the elastic force of the return spring 3 to open the spill passages 11 and 13, whereby the fuel is supplied to the fuel outlet passage 13 and the communication passage. The cam chamber 43 is spilled (overflowed) via 22 to stop the pressure feeding of fuel to the diesel engine.

FIG. 3 is a timing chart for explaining the operation of the electromagnetic spill valve 20 according to the first embodiment of the present invention described above. FIG. 3 (A) shows the needle valve drive signal, and the solenoid 2 of the electromagnetic spill valve 20 is sent from the ECU.
Is a signal supplied to. Further, FIG. 3B shows the lift amount of the needle valve 4. Further, FIG. 3C shows a period in which the notch for valve closing assist 35 communicates with the communication passage 23. Further, FIG. 3D shows a period during which the intake port 32 communicates with the fuel intake gallery 57. Also,
FIG. 3E shows a period in which the discharge port 33 communicates with the discharge passage 25. Further, FIG. 3 (F) shows the inner cam 45.
Shows the cam lift of.

Here, comparing the valve-closing assist notch communication period shown in FIG. 3 (C) with the intake port communication period shown in FIG. 3 (D), the valve-closing assist notch communication period is connected to the intake port. Within the period. Accordingly, the post-valve closing assist notch 35, which has entered the intake port communication period, communicates with the communication passage 23 and introduces the assist fuel pressurized by the feed pump 42 into the hydraulic chamber 8.

Next, pay attention to the lift amount of the needle valve 4 shown in FIG. In the figure, the lift amount of the needle valve 4 in the fuel injection pump 40 having the configuration according to the present embodiment (shown by the solid line) and the lift amount of the needle valve in the conventional fuel injection pump (shown by the broken line) are combined. I am drawing. As is apparent from the figure, the closing operation of the needle valve 4 in the fuel injection pump 40 having the configuration according to the present embodiment is completed faster than the closing operation of the conventional needle valve. Therefore, it can be seen that the valve closing characteristic is better than the conventional one.

As described above, this is because the notch for valve closing assist 35 communicates with the communication passage 23 after the intake port communication period is entered, and the assist fuel pressurized by the feed pump 42 is introduced into the hydraulic chamber 8. This is because the fuel pressure biases the needle valve 4 in the valve closing direction. Therefore, it is proved from FIG. 3 that the closing operation of the needle valve 4 in the fuel injection pump 40 having the configuration according to the present embodiment is faster and the closing response is better than the closing operation of the needle valve in the conventional fuel injection pump. To be done.

As described above, the pressure introduction passage 16 is provided with the throttle 18, and the pressure relief passage 17 is provided with the throttle 19. Therefore, the fuel pressure of the assist fuel introduced into the hydraulic chamber 8 is adjusted by appropriately selecting the diameter size of each throttle 18, 19 and adjusting the fuel amount of the assist fuel passing through each throttle 18, 19. The needle valve 4 is configured so that an optimum pressure is applied to the needle valve 4.

Next, a solenoid valve device according to a second embodiment of the present invention will be described.

FIG. 4 shows an electromagnetic valve device (electromagnetic spill valve) 60 which is a second embodiment of the present invention. The electromagnetic spill valve 60 according to this embodiment corresponds to claim 2. Further, in FIG. 4, the same components as those of the electromagnetic spill valve 20 according to the first embodiment shown in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted.

The electromagnetic spill valve 60 of the second embodiment has a fuel outlet passage 13 disposed downstream of the position where the needle valve 4 of the spill passages 11 and 13 through which spill fuel passes is closed. A pressure introducing passage 61 (constituting a spill fuel introducing pipe) communicating with the hydraulic chamber 8 and a pressure relief passage 62 are provided. Restrictors 63 and 64 are provided at predetermined positions in the pressure introduction passage 61 and the pressure relief passage 62.

As described above, the fuel outlet passage 13 and the hydraulic chamber 8
By providing the pressure introduction passage 61 between and, the spill fuel flowing through the fuel outlet passage 13 can be introduced into the hydraulic chamber 8 via the pressure introduction passage 61. The spill fuel introduced into the hydraulic chamber 8 presses and urges the upper surface of the needle valve 4 downward. When the pressure in the hydraulic chamber 8 exceeds a predetermined value, the fuel in the hydraulic chamber 8 is released from the pressure relief passage 6
2, it is configured to be discharged to the cam chamber 43 via the communication passage 24. Further, the predetermined value can be determined by the diameter of each of the diaphragms 63 and 64.

Subsequently, the electromagnetic spill valve 6 having the above structure
The operation of 0 will be described with reference to FIG. 5 in addition to FIG. FIG. 5 is a timing chart for explaining the operation of the electromagnetic spill valve 60 according to the second embodiment of the present invention described above. FIG. 5A shows a needle valve drive signal. Further, FIG. 5B shows the lift amount of the needle valve 4. Further, FIG. 5C shows the pressure in the fuel inlet passage 11 upstream of the needle valve 4. Also, FIG.
(D) shows the pressure in the hydraulic chamber 8. Also, FIG.
(E) shows a period during which the suction port 32 communicates with the fuel suction gallery 57. Further, FIG. 5F shows a period in which the discharge port 33 communicates with the discharge passage 25. Further, FIG. 5 (G) shows the cam lift of the inner cam 45.

As described above, when the fuel pressure in the fuel outlet passage 13 rises, this rise in fuel pressure is caused by the pressure introduction passage 6
1 is transmitted to the hydraulic chamber 8 and the pressure in the hydraulic chamber 8 also rises. The pressure increase in the hydraulic chamber 8 is shown by an arrow B in FIG. Therefore, when the needle valve 4 closes, the needle valve 4 closes due to the pressure of the spill fuel introduced into the hydraulic chamber 8 in addition to the magnetic force generated by the excitation of the solenoid 2 The needle valve 4 can be closed with good performance.

Further, as described above, in the needle valve 4, the diameter dimension D _S of the disk-shaped portion 4a which is the pressure receiving portion of the pressurized fuel is larger than the diameter dimension D _N of the valve portion 4b, and therefore the pressure receiving area is wide, Even if the pressure of the fuel pressurized by the feed pump 42 per unit area is smaller than the pressure of the spill fuel, it is possible to increase the oil pressure (assist force) that urges the needle valve 4 downward. This is similar to the first embodiment described above.

The needle valve 4 is moved downward by being biased by the magnetic force generated in the solenoid 2 and the pressure of the spill fuel introduced into the hydraulic chamber 8 as described above, and the needle valve 4 causes the spill passages 11 and 13 to move. Is blocked. Therefore, the overflow (spill) of the high-pressure fuel pressurized in the plunger chamber to the cam chamber 43 through the fuel outlet passage 13 and the communication passage 22 is stopped.

Therefore, also in the structure according to the second embodiment, the pressure of the spill fuel is utilized even in the spill passages 11 and 13 in which a force acts in the valve opening direction due to the flow of the high-pressure spill fuel. The needle valve 4 can be closed with good response. Further, by improving the valve closing response of the needle valve 4 in this way, it is possible to reliably prevent the occurrence of the injection amount shortage due to the filling failure due to the feed pressure loss in the intake process of the diesel engine. The same as the first embodiment.

Further, in the configuration according to the second embodiment, the hydraulic chamber 8
The spill fuel flowing through the spill passages 11 and 13 is used as the pressurized fuel introduced into the spill fuel instead of the fuel pressurized by the feed pump 42. Therefore, the piping system can be easily arranged, and the electromagnetic spill valve 60 and the fuel injection can be injected. The structure of the pump can be simplified. Further, since the path length of various pipes for introducing the pressurized fuel to the hydraulic chamber 8 can be made shorter than that of the configuration of the first embodiment, the pressure loss during flowing through the pipes can be reduced, and the fuel of high pressure can be reduced. Can be introduced into the hydraulic chamber 8, which also improves the valve closing characteristic of the needle valve 4.

When the energization of the solenoid 2 is stopped, the needle valve 4 is moved upward by the elastic force of the return spring 3 to open the spill passages 11 and 13, whereby the fuel is supplied to the fuel outlet passage 13 and the communication passage. The cam chamber 43 is spilled (overflowed) via 22 to stop the pressure feeding of fuel to the diesel engine.

Subsequently, the electromagnetic spill valve 6 according to the second embodiment.
The fuel injection pump 70 using 0 is shown in FIG. 6, and the control operation of the electromagnetic spill valve 60 will be described. In FIG. 6, the same components as those of the fuel injection pump 40 described with reference to FIG. 2 in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

In the figure, 71 is a fuel injection control device (hereinafter referred to as ECU), which is constituted by a microcomputer. Specifically, the ECU 71 includes a central processing unit (CPU), a read-only memory (ROM) in which a predetermined control program, maps and the like are stored in advance, and a CP.
Random access memory for temporarily storing the calculation result of U, backup R for storing pre-stored data
It is composed of an AM, a clock for generating a predetermined clock signal, and the like.

The ECU 71 performs opening / closing valve control of the electromagnetic spill valve 60 and other control processing for properly operating the diesel engine based on information from various sensors provided in the diesel engine and the fuel injection pump 70. . In the present embodiment, the electromagnetic spill valve 6
Since the open / close valve control of 0 is characteristic, only those necessary for this open / close valve control will be illustrated and described.

As information for controlling the opening / closing of the electromagnetic spill valve 60, an engine speed signal (NE signal) is supplied from the NE sensor 46 to the ECU 71, and an accelerator opening signal (ACCP) is supplied from the accelerator opening sensor 72. Is supplied. The ECU 71 is connected to the electromagnetic spill valve 60, and the solenoid 2 provided in the electromagnetic spill valve 60 is connected to the ECU 2.
The needle valve 4 can be opened and closed by energizing the.

In the above-mentioned configuration, the opening / closing control processing of the electromagnetic spill valve 60 executed by the ECU 71 will be described with reference to FIGS.
Will be explained. The spill passage pressure detecting means and the valve driving means described above are configured as a software program executed by the ECU 71.

FIG. 7 is a flowchart showing the opening / closing control processing of the electromagnetic spill valve 60 executed by the ECU 71.

When the processing shown in the figure is started, first, at step 10 (step is abbreviated as S in the figure), N
The NE signal output by the E sensor 46 is read, and the accelerator opening signal (A
CCP). Then, the engine speed (NE) is calculated based on the read NE signal, and the injection command value (QFIN) is calculated from the engine speed NE and the accelerator opening signal ACCP. This injection command value Q
FIN is a value that indicates the most suitable fuel injection amount for optimal operation of the diesel engine in the current operating state of the diesel engine, and this injection command value QFI
The opening / closing control of the electromagnetic spill valve 60 is performed based on N.

In the following step 12, the electromagnetic spill valve 60 is opened based on the engine speed NE and the injection command value QFIN obtained in step 10, and then the spill passage 11,
The time t1 required for the spill passage pressure 13 to drop to near the feed pressure generated by the feed pump 42 (hereinafter,
This time is called pressure drop time t1). Specifically, the pressure drop time t1 is calculated in advance in the ROM of the ECU 71.
Engine speed NE and injection command value Q stored in
It is determined by a two-dimensional map with FIN (shown in FIG. 8).

This pressure drop time t1 depends on the electromagnetic spill valve 6
It is determined by the fuel pressure flowing through the spill passages 11 and 13 when 0 is opened. That is, when the fuel pressure of the fuel flowing through the spill passages 11 and 13 is high, the pressure drop time t1 becomes long, and conversely, when the fuel pressure of the fuel flowing through the spill passages 11 and 13 is low, the pressure drop time t1 becomes short. The fuel pressure of the fuel flowing through the spill passages 11 and 13 is related to the engine speed NE and the injection command value QFIN. The higher the engine speed NE is, the higher the fuel pressure is. Similarly, the larger the injection command value QFIN is. The fuel pressure becomes high. Therefore, the pressure drop time t1 can be obtained from the two-dimensional map shown in FIG. 8 using the engine speed NE and the injection command value QFIN as parameters. It should be noted that the specific value of the pressure drop time t1 determined by the engine speed NE and the injection command value QFIN shown in FIG. 8 is previously obtained by an experiment.

In step 12, the pressure drop time t1
Is calculated, in the subsequent step 14, the electromagnetic spill valve 60 based on the latest pulse is opened (SPV OFF).
Time (t _OFF ) and the electromagnetic spill valve 60 is closed (SPV
The time to turn on (t _ON ) is calculated.

Here, how to determine the timing (spill timing) for opening the electromagnetic spill valve 60 will be described.

Normally, the spill timing is determined based on the NE signal output from the NE sensor 46. That is, the pulsar 47, which is arranged on the drive shaft 44 so as to face the NE sensor 46, has missing teeth corresponding to the number of cylinders. ) Count the number of NE signals output by
The electromagnetic spill valve 60 is opened when the sum of the counts reaches a value corresponding to the spill time.

However, in the case of the above configuration, if the NE signal output from the NE sensor 46 is infinitely large and the spill timing can be determined only by the number of pulses, highly accurate fuel injection control is possible, but in reality, It is impossible to increase the number of pulses infinitely.

Therefore, in order to correct the above inconvenience,
Generally, the pulse number of the NE signal is counted from the reference position (missing tooth position), and if the injection command value QFIN is located between the teeth, the spill timing is converted by time conversion of the surplus angle. A decision is being made.
The time obtained by converting the time as described above is the time t for opening the electromagnetic spill valve 60 described above.
_OFF (Hereinafter, this time t _{OFF is referred} to as the extra time t _OFF )
Becomes Therefore, the spill timing can be expressed as (spill timing) = (predetermined number of pulses) + (remaining time t _OFF ).

By the way, this remaining time t_OFFTo ask
Is the time for one pulse and the crank angle for one pulse
The time conversion process is performed on the basis of
The crank angle for the lus is always constant, but one pulse
The minute time is a value that varies depending on the engine speed NE, etc.
It Therefore, it is necessary to
The remaining time t based on the time corresponding to one pulse_OFFCalculate
If you do not issue it _OFFThe accuracy of will decrease.
Therefore, in the present embodiment, the most recent position of the pulse in which the valve closing timing exists
Based on pulse time of pulse (ie previous pulse)
Time left t_OFFIs calculated. In addition, this
The details of the calculation method of the remaining time are, for example, first published by the applicant.
Reference was made to Japanese Patent Application Laid-Open No. 62-267547
Yes.

As described above, when the time for opening the electromagnetic spill valve 60 based on the latest pulse (that is, the remaining time t _OFF ) is calculated, the electromagnetic spill valve 60 based on the latest pulse is subsequently operated. The time (t _ON ) for closing the valve is calculated.

As described above, when the electromagnetic spill valve 60 is closed, the spill passage pressures of the spill passages 11 and 13 are relatively low due to the inertia while the needle valve 4 is open for a while. A large amount of fuel flows through the spill passages 11 and 13. Therefore, in the fuel injection pump using the electromagnetic spill valve having a structure that does not have a mechanism for assisting the valve closing operation when closing the needle valve as in the conventional case, the spill passage is formed in a state where a large amount of fuel is flowing. A large valve closing force was required to shut off the valve midway, and a large valve closing force had to be generated in the solenoid, which required a large amount of electric power.

However, the electromagnetic spill valve 6 according to the present embodiment.
0 indicates that when the needle valve 4 closes, the needle valve 4
Is urged by the magnetic force generated in the solenoid 2 and the pressure of the spill fuel introduced into the hydraulic chamber 8 to move downward. That is, since the needle valve 4 is closed by using the pressure of the spill fuel as an assist force, a large flow rate of fuel flows due to inertia in the spill passages 11 and 13 without supplying a large amount of electric power to the solenoid 2. Even in this case, the needle valve 4 can be closed with good response. However, when the fuel pressure of the fuel flowing through the spill passages 11 and 13 is high, it is difficult to improve the responsiveness of the needle valve 4 even if the above assist force is applied.

Therefore, in this embodiment, the spill passages 11 and 1 are
When the spill passage pressure of No. 3 falls near the feed pressure generated by the feed pump 42, the spill passages 11, 1
Electromagnetic spill valve 6 even when a large amount of fuel is flowing to 3
It is characterized in that it is configured to close 0.

Therefore, when the valve closing timing is determined, after the electromagnetic spill valve 60 is opened, the pressure drop time t1 obtained in step 12 (the spill passage pressure of the spill passages 11 and 13 is generated by the feed pump 42). The electromagnetic spill valve 60 is closed after the elapse of the time required for the pressure to drop to near the feed pressure).

That is, the time t for closing the electromagnetic spill valve 60.
_ONIs based on the most recent pulse (t _ON) = (T_OFF) +
It is calculated as (t1).

By determining the time t _ON for closing the electromagnetic spill valve 60 as described above, the ECU 71 immediately starts the electromagnetic spill valve 60 when the spill passage pressure falls near the feed pressure generated by the feed pump 42. Since the needle valve 4 is driven to close, it is possible to prevent the valve opening period and the suction process from overlapping, and it is possible to improve the fuel suction property.

Further, as described above, in the state immediately after the closing operation of the needle valve 4 is started, the needle valve 4 has the magnetic force generated by the excitation of the solenoid 2 and the spill passage 11,
Since the valve closing operation is performed by both forces of the pressure of the high-pressure fuel introduced from 13 to the pressure chamber 8, the valve closing response of the solenoid valve device is improved. Therefore, even if the needle valve 4 is driven to close the valve immediately when the spill passage pressure decreases, it is not necessary to generate a large valve closing force in the solenoid 2 and the valve closing operation can be performed with a small amount of electric power.

[0098]

As described above, according to the present invention, the following various effects are exhibited.

According to the first aspect of the invention, when the fuel injection pump is in the suction process, the fuel pressurized by the feed pump by the pressurized fuel introducing mechanism is introduced into the pressure chamber and introduced into this pressure chamber. Since the pressurized fuel urges the needle valve in the valve closing direction, the valve closing characteristic of the solenoid valve device can be improved.

According to the second aspect of the invention, the high-pressure fuel (spill fuel) introduced from the spill passage into the pressure chamber urges the needle valve in the valve closing direction, and the solenoid is energized to start the needle valve. The spill passage is not completely closed by the needle valve immediately after the valve closing operation of the spill passage is started, and therefore the spill fuel flowing through the spill passage is introduced into the pressure chamber through the spill fuel introduction pipe. Immediately after the valve closing operation starts, the valve closes due to both the magnetic force generated by the solenoid's excitation and the pressure of the high-pressure fuel introduced into the pressure chamber from the spill passage. The valve closing response can be improved.

When it is detected by the spill passage pressure detecting means that the spill passage pressure has dropped close to the feed pressure generated by the feed pump, the valve driving means energizes the solenoid to immediately drive the needle valve to close. Since the valve is driven, it is possible to prevent the valve opening period and the suction process from overlapping, and it is possible to improve the fuel suction property.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an electromagnetic spill valve that is a first embodiment of the present invention.

FIG. 2 is a piping system diagram of a fuel injection pump to which the electromagnetic spill valve according to the first embodiment of the present invention is applied.

FIG. 3 is a diagram for explaining the operation of the electromagnetic spill valve that is the first embodiment of the present invention.

FIG. 4 is a sectional view of an electromagnetic spill valve according to a second embodiment of the present invention.

FIG. 5 is a diagram for explaining the operation of the electromagnetic spill valve according to the second embodiment of the present invention.

FIG. 6 is a piping system diagram of a fuel injection pump to which an electromagnetic spill valve according to a second embodiment of the present invention is applied.

FIG. 7 is a flowchart showing a control process of an electromagnetic spill valve executed by an ECU.

FIG. 8 is a diagram showing a map used for control processing of an electromagnetic spill valve.

[Explanation of symbols]

 1 body 2 solenoid 3,5 return spring 4 needle valve 6 armature 7 armature chamber 8 hydraulic chamber 9 seat member 11 fuel inlet passage 12 body seat surface 13 fuel outlet passage 14 needle guide surface 16,61 pressure introduction passage 17,62 pressure relief Passage 18, 19, 63, 64 Throttle 20, 60 Electromagnetic spill valve 21-24 Communication passage 30 Rotor 31 Plunger 32 Suction port 33 Discharge port 34 Spill port 35 Notch for valve closing assist 36 Annular groove 40, 70 Fuel injection pump 41 Fuel Tank 42 Feed pump 43 Cam chamber 44 Drive shaft 45 Inner cam 46 NE sensor 48 Timer device 50 Timing control valve 51 Fuel injection valve 57 Fuel intake gallery 71 ECU 72 Accelerator position sensor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshio Fujimura 1 Toyota-cho, Toyota-shi, Aichi Toyota Automobile Co., Ltd. (72) Inventor Koichi Nagatani 1-1 1-1 Showa-cho, Kariya-shi, Aichi Nihon Denso Co., Ltd. In the company

Claims (2)

[Claims] 1. A spill passage including an inlet passage and an outlet passage formed in a body, a solenoid disposed in the body for generating an electromagnetic force, a needle valve for opening and closing the spill passage, An electromagnetic force of a fuel injection pump, which is provided in a fuel injection pump having a feed pump for pressurizing fuel, the valve body having an armature portion for displacing the needle valve when an electromagnetic force of the solenoid is applied. In the valve device, the pressurized fuel is introduced from the feed pump so that the pressurized fuel urges the needle valve in the valve closing direction, and the fuel injection pump is used for the suction process. A solenoid valve device for a fuel injection pump, comprising a pressurized fuel introducing mechanism for introducing fuel pressurized by the feed pump into the pressure chamber at a certain time. 2. A spill passage which is formed in the body and has an inlet passage and an outlet passage, a solenoid which is arranged in the body and generates an electromagnetic force, and a needle valve which opens and closes the spill passage. An electromagnetic force of a fuel injection pump, which is provided in a fuel injection pump having a feed pump for pressurizing fuel, the valve body having an armature portion for displacing the needle valve when an electromagnetic force of the solenoid is applied. In the valve device, a pressure chamber for introducing pressurized fuel for urging the needle valve in a valve closing direction is communicated with the pressure chamber and a downstream side of an opening / closing position of the spill passage by the needle valve. A spill fuel introducing pipe for introducing the spill fuel flowing through the spill passage into the pressure chamber as the pressurized fuel, and a spill passage pressure in the spill passage is a feed pressure generated by the feed pump. When the spill passage pressure detection means detects that the spill passage pressure has dropped to the vicinity of the feed pressure generated by the feed pump, the solenoid is energized. A solenoid valve device for a fuel injection pump, which is provided with valve driving means for driving the needle valve to close the valve immediately.