JPS59211724A - Fuel control device - Google Patents

Abstract

PURPOSE:To enhance the responsiveness of a fuel pressure control device for a fuel injection pump in an internal combustion engine, by extending the cylindrical part of a valve body in a hydraulic shut-off valve inward of a spool. CONSTITUTION:A fuel pressure control device 8 is provided with a solenoid valve 81 and a spool valve 82 as a hydraulic shut-off valve. The cylindrical part 821h-1 of a valve body 821h in the spool valve 82 is extended inward of the spool 822 to form a first hydraulic pressure chamber 824. When the solenoid 811 of the solenoid valve 81 is deenergized, the communication of the first hydraulic pressure chamber 824 in interrupted to the relief system and therefore fuel is injected to the engine. On the contrary when the solenoid 811 is energized, the injection is terminated. With this arrangement, since the volume of the first hydraulic pressure chamber 824 is reduced, the responsiveness of intiation and termination of fuel-injection may be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention is incorporated into a part of a fuel supply system of an internal combustion engine,
The present invention relates to a fuel control device that recirculates fuel discharged from a pump to a tank or stops this recirculation in order to stop or start fuel supply to a fuel injection nozzle.

Prior Art Conventionally, in this type of fuel control device, there was one in which a relief port for recirculating fuel to a tank was controlled to open and close by a solenoid valve.However, for example, in order to instantly stop fuel injection, In order to discharge a large amount of fuel from this relief port, it is necessary to increase the flow area of the relief port, so the solenoid valve must be made larger.In other words, in order to increase the lift amount of the valve body, a solenoid valve is used. In addition to increasing the size of the solenoid, it is also necessary to increase the size of the portion of the valve body into which the solenoid is inserted, resulting in the problem that the entire fruiting device becomes expensive and it is difficult to obtain sufficient responsiveness.

OBJECT OF THE INVENTION In view of the above points, the present invention has been made with the object of providing a fuel control device that is simple and compact and has excellent responsiveness.

Structure of the Invention In order to achieve the above-mentioned object, the first aspect of the present invention is a high-pressure system for pumping fuel to a fuel injection nozzle. This device controls the fuel pressure in the pressure chamber in the cylinder, and includes a cylinder body having first and second relief ports for returning fuel to the low pressure chamber, and a cylindrical spool is movable within the cylinder body. A first hydraulic chamber is provided on one side of the spool, and a second hydraulic chamber that is constantly in communication with the pressure chamber is formed on the other side of the spool, and the first hydraulic pressure and the second hydraulic chamber are formed in the spool. An electric on-off valve is provided which communicates with each other via the throttle and controls opening/closing of the first relief port with respect to the first hydraulic chamber.
The spool, which is moved by the differential pressure between the hydraulic chamber and the second hydraulic chamber, is the second relief tr? -) is normally biased by a spring to separate it from the second hydraulic chamber, and furthermore, the part of the cylinder body that forms the first relief port is connected to the first hydraulic chamber from the spool end to the syspool. It is characterized by being extended so that it can be slid in a sealed manner between the shaped peripheral surfaces.

A second aspect of the present invention is a device for controlling the fuel pressure in a pressure chamber in a high-pressure pump that pressure-feeds fuel to a fuel injection nozzle.
A cylindrical spool is movably provided in the cylinder body, and a first hydraulic chamber is provided on one side of the spool, and a second hydraulic chamber that is in constant communication with a pressure chamber is provided on the other side of the spool.
A hydraulic chamber is formed, and the first hydraulic chamber and the second hydraulic chamber are communicated with each other via a restriction formed in the spool.
An electric on-off valve is provided to control the opening and closing of the relief port of the first hydraulic chamber, and the second hydraulic chamber is operated by the spool, which is moved by the differential pressure between the first hydraulic chamber and the second hydraulic chamber. is opened and closed with respect to the second relief port, and an adjuster is provided on the opposite side of the spool, sandwiching the valve body of the solenoid valve, and a closeable lift adjustment is provided in the center of the adjuster for adjusting the lift of the valve body. It is characterized in that a hole is bored and a lift adjustment means is provided.

A third aspect of the present invention is a device for controlling fuel pressure in a pressure chamber in a high-pressure pump that pumps fuel to a fuel injection nozzle, the first and second relief ports for recirculating fuel to the low-pressure chamber. A cylindrical spool is movably provided in the cylinder body, a first hydraulic chamber is formed on one side of the spool, and a second hydraulic chamber is formed on the other side of the spool in constant communication with the pressure chamber, The first hydraulic pressure and the second hydraulic chamber are communicated with each other via a throttle formed in the spool, and an electric opening/closing control is used to control the opening/closing of the first IJ-7 port with respect to the first hydraulic chamber. A valve is provided to connect the first hydraulic chamber and the second hydraulic chamber.
The second hydraulic chamber is opened and closed with respect to the second relief port by the spool, which is moved by the differential pressure with the hydraulic chamber of the solenoid valve.
The recirculated fuel from the second relief port is returned via the solenoid chamber.

EXAMPLE Below, an example embodying the present invention will be described. In FIG. 1, the number l is a high-pressure pump.

As the high-pressure pump 7'l, a distribution pump that is normally used as an injection pump is used, but the high-pressure pump does not need a governor and a timer. The granger 11 of the high-pressure pumper 1 is connected to the drive shaft 5 with a coupling (not shown) that allows sliding in the axial direction, and the face cams 11aFi, yf! It cooperates with rollers 6' on a roller ring 6 provided in the housing 4. As a result, the plunger 11 is driven by an engine (not shown) and rotates and reciprocates in synchronization with the rotation of the rod of the engine. The suction stroke is when the first notch groove 12 of the granger 11 is in communication with the suction port 14 of the cylinder 13, and the syringer 11 moves to the left in the figure to transfer fuel oil to the cylinder 13 and the tip of the granger 11. The air is sucked into a pressure chamber 131 formed in a large area. The discharge stroke is when the second notch groove 15 of the granger and the discharge port 16 of the cylinder 13 are electrically connected, and the syringer 11 moves fuel oil from the pressure chamber 131 to the notch groove while moving to the right in the figure. 15, discharge port 16, high pressure line 18 via discharge valve 23
Send to. The time when the plunger 11 starts to move to the right is sufficiently earlier than the time when the injection nozzle 2 is requested to start injection, and the time when the plunger 11 stops moving to the right is when the injection nozzle 2 is requested to stop injection. A fixed time is given so that the timing is sufficiently late.

The fuel in the tank 7 is fed under pressure to the tank 21 via the feed pump f3 and the low pressure line 17, and is supplied from the tank 21 to the intake port 14 of the cylinder 13. Fuel discharged from the discharge port 16 of the cylinder 13 by the action of the high pressure pump 10 is supplied to the injection nozzle 2 via the high pressure line 18. The pressure in the pressure chamber 131 is controlled by the fuel control device 8 as described below.

The fuel control device 8 includes a cylindrical housing 80, which is connected to the pump housing 4 by a threaded portion 808.
mounted on. Disk 50 at the front end of housing 80
is screwed into the disc 50, and an annular projection 50 is formed on the outer periphery of the disc 50.
a is formed and pressed against the end face of the cylinder 13 to ensure a seal, whereby the pressure chamber 131 is formed by the syringe 11, the cylinder 13 and the disk 50.

The fuel control device 8 includes a solenoid valve 8 as an electric on-off valve.
1 and a spool valve 82 as a hydraulic opening/closing valve.

The spool valve 82 consists of a through hole, a cylinder body 821, a spool 822, and a spring 823, which are shown on an enlarged scale in FIG. The cylinder body 821 has a separate valve.
The pulp die 821h is inserted into the cylindrical hole 801 formed in the housing 80 until it reaches the shoulder 801m, and then the cylinder body 821 and further the distance piece 49 are inserted and fastened by the disk 50. Retained. The valve body 821h has a cylindrical projection 82]h-1 in its center that extends into the system pool from the end of the stool 822 opposite to the pressure chamber 131, and has a The stool 822
is fitted on its inner periphery so as to be slidable in the axial direction. However, the outer peripheral surface of the cylindrical projection 821h-1 and the stool 8
It maintains a seal with the inner circumferential surface of 22 and prevents fuel from flowing out via this sliding surface. The spool 822 has a stepped outer peripheral surface, and as a result, an annular streaking chamber 824b is formed between the stool 822 and the cylinder body 821. A spring 823 is disposed within this annular spring chamber 824b, so that the stool 822 is biased against the distance piece 49.

821a and 821ha are first and second relief ports, respectively. The second relief port 821b is curved in the cylindrical part of the cylinder body 821, and its outer end connects to the annular passage 51 around the cylinder body and the return passages 52 and 53.
The annular IJ is connected to the annular IJ-F chamber 54 formed on the outer periphery of the annular projection 50a of the disk between the opposing end surfaces of the pump housing 4 and the cylindrical housing 80 via. This annular relief chamber 54 is a relief passage 13' in the cylinder 13.
It is communicated with the tank 21 via.

The first relief port) 821m is a pallet f? extending inside the spool 822. Cylindrical protrusion portion 821 of di 821h
h-1, and is opened and closed by a through solenoid valve 81, which will be described later.

The spool 822 has central holes of different diameters at its ends, resulting in the formation of first and second hydraulic chambers 824 and 825, which communicate with each other by a restrictor 826. The hydraulic chamber 826 constantly communicates with the pressure chamber 131 via the center hole of the distance piece 49 and the center hole of the disk 50. As mentioned above, the spring 823 is attached to the stool 822
exerts a biasing force that comes into contact with the distance piece 49, and normally the second hydraulic chamber 825 is connected to the second relief port 8.
We have cut off communication since 21h.

The electric on-off valve 81 includes a cylindrical solenoid 811 and a valve body 812 provided in the center thereof so as to be movable in the axial direction. Valve body 8
From 12, a needle 812a extends into the valve 821h, and its tip is connected to the first relief port 821a.
is selectively opened to the first hydraulic chamber 824. A cylindrical rod 815 is located at the center of the cylindrical solenoid 811, which also functions as a valve lift adjuster, as will be described later.

The aforementioned valve body 812 is provided close to one end of the cylindrical rod 815, and the spring 813 is such that the tip of the needle 812a is normally in the first position.
the law of nature! J-7 port) 821m from the first hydraulic chamber 824.

A gap S between the facing surfaces of the valve body 812 and the cylindrical rod 815 corresponds to the lift of the valve body 812. A lift adjustment hole 815a is bored in the center of the cylindrical rod 815, and is closed by a blind stopper 816 after adjusting the height.

The solenoid 811 is housed in a solenoid chamber 88 formed within the housing 80.
constitutes a part of the relief piping system between the relief passages 52 and 53.

811& and 811b are connectors to both winding ends of the solenoid 811, respectively, and are connected by lead wires 61 and 62.
It is connected to a control circuit 20 that controls energization of the solenoid valve 81 . The control circuit 20 operates the solenoid 8 at an appropriate time and for an appropriate period according to the accelerator opening degree and the engine speed signal.
11 is energized.

The accelerator opening signal is transmitted by a detent meter 211 provided on the accelerator pedal 21. Engine phase signals for knowing the pump rotation speed and timing are transmitted by two MRE (magnetoresistive element) sensors 41 and 42 provided in the pump casing 4. The sensor 42 detects the irregularities of a gear 51 fixed to the drive shaft 5 that rotationally drives the syringe 11, and the sensor 41 detects one protrusion 511 provided on the side surface near the outer periphery of the gear 51. That is, the sensor 42 detects the unevenness of the teeth provided at 5° intervals, and sends two shift signals per rotation to the Punpyu and Yu 20, and the sensor 41 detects one shift signal per rotation. The initial pulse signal is transmitted to the computer 20. Based on these signals, the computer 20 calculates the injection start timing and end timing and energizes the solenoid 811.

The rotation of the input shaft 5 is converted into reciprocating motion while the plunger 11 rotates by a mechanism consisting of the face cam 11a and the roller 6' on the roller ring 6. Plunger 11
When the suction stroke moves to the left in Fig. 1, the tank 21
The fuel inside flows into the pressure chamber 1 through the suction port 14 and the notch groove 12.
It was introduced in 31.

When the plunger 11 moves to the right, it is a pressure feeding stroke, and the fuel in the pressure chamber 131 is pressurized.

When the syringe performs a pumping stroke, the sensor 41.4
The control circuit 20 calculates the injection period based on the signal from the solenoid 811, and when it is determined to be the injection period (relief stop), stops energizing the solenoid 811. At this time, the valve body 812 is pushed to the left in the figure by the spring 813, and the needle 812
The tip of a is the second relief port for the first hydraulic chamber 824)
821a, and the inner periphery of the spool 822 and the outer periphery of the knob body 821h are sealed, so the first hydraulic chamber 824 is sealed from the relief system. -Power cylinder 2
Regarding the hydraulic chamber 825, the end face of the spool 822 is urged by the spring 823 against the end face of the distance piece 49, and at this time, the pressure in the second hydraulic chamber 825 does not exceed the set value of the spring 823, so the second The relief port 821b is also closed to the pressure chamber 825.

Therefore, all the relief systems of the fuel control device are closed, and the fuel in the pressure chamber 131 is supplied to the injection nozzle 2 via the notch groove 15, the discharge port 16, the delivery valve 17, and the pipe 18, and injection is performed. When this relief stops, the spool 822 must be closed, but in this case, it is desirable that the force relationship acting on the spool 822 be selected as follows.

That is, when the valve body 812 is closed, the force F1 that presses the spool 822 from the right side of the restrictor 826 in the direction of closing the spool 822 is the product of the fuel pressure P and the area 81 of the pressure receiving surface 822a.
Force F that presses the spool 822 from the left side of the diaphragm 826 in the direction of opening it! is the fuel pressure P and the area S- of the pressure receiving surface 822b
The relationship between these forces is F1≧
F.

It is. If F's<Fm is selected, there is a possibility that the spool 822 will move one step to the right and be relieved even if the valve body 812 is closed by overcoming the force of the sgel ring 823.

Next, the injection ends (!J
! J-7 start), the control circuit 20 energizes the solenoid 811, and as a result, the valve body 812
moves to the right in the figure against the spring 813 to open the second relief port 821a, and as a result, the second hydraulic chamber 824 is
It opens into the annular relief passage 51 through a gap between the needle 812a and the valve body 821h. Therefore, the second
The pressure within hydraulic chamber 824 drops. Because of this pressure drop, the pressure difference between the first hydraulic chamber 824 and the second hydraulic chamber 825 is large, and the spool 822 is displaced to the right in the figure against the spring 823, and as a result, the second hydraulic chamber 825 is Second reliever?
-) 821b, the pressure in the pressure chamber 131 drops,
Fuel injection from the injection nozzle 2 is stopped. At the time of this relief, the cylindrical protrusion 821h of the valve body 821h-
1 is extended into the spool 822 and the first hydraulic chamber 824 is provided in front of the spool 822, so that the volume of the first hydraulic chamber 824 can be kept extremely small. Since the volume of the first hydraulic chamber 824 is small, the pressure in the first hydraulic chamber 824 decreases rapidly after the needle 812a opens the first relief port 821m, and as a result, the main relief due to subsequent movement of the spool 822 occurs. The start of the program will also be swift. Furthermore, regarding the responsiveness after closing the first relief port 824b to stop relief, the pressure rises quickly because the volume of the first hydraulic chamber 824 is made small, and the spool 822 is quickly closed. It can be tightened.

Regarding this responsiveness, the present invention provides a lift adjustment mechanism for the valve body 812 of the electric on-off valve 81.

That is, when the lift amount of the valve body 81 is increased, the response becomes slower, whereas when the lift amount of the valve body 81 is decreased, the response line becomes faster. Considering the aspect of mass production, it is necessary to maintain constant responsiveness. As mentioned above, the cylindrical rod 815 as a lift adjuster has a lift adjustment hole 81 with a diameter of about 2 ms.
5a is provided, and one end is closed with a set screw 816. At the time of assembly, the thickness of the shim 819 is adjusted a so that the lift amount of the valve body 812 is constant. In order to measure the amount of lift, a υ bar is inserted into the lift adjustment hole 815a provided in the adjuster 815, and the amount of lift is measured using a dial gauge, micrometer, or the like.

The constant responsiveness can also be improved by locating the solenoid 811 in the chamber 88 provided in the middle of the relief passage. That is, when the temperature of the coil rises due to energization of the solenoid, the resistance value changes, and the responsiveness changes as the coil heats up. In order to stabilize the response,
In this embodiment, the structure is such that the relieved fuel is returned to the low pressure side of the high pressure ponzo 1 through the relief passage 53 after passing through the solenoid chamber 88 which houses the solenoid 811 and is sealed from the outside. The solenoid is maintained at an appropriate temperature through heat exchange with the recirculated fuel.

In the above embodiment, an electrically acting solenoid valve 81 is used, but the valve is not limited to a solenoid, and may be a valve that utilizes a magnetostrictive effect or an electrostrictive effect.

In the above embodiment, a face seal is performed between the susol 822 and the pulp die 821h, but in order to prevent seizure, several grooves may be provided on the outer periphery of the pulp die 821h, or a labyrinth packing may be used. Effective.

Effects of the Invention According to the present invention, by extending the cylindrical portion of the pulp chamber inward, the volume of the first hydraulic chamber can be reduced, thereby achieving a structure with excellent responsiveness. can do. Further, by installing a lift control mechanism and a solenoid temperature control means, it is possible to maintain constant responsiveness.

[Brief explanation of the drawing]

FIG. 1 is a combined configuration diagram of a fuel supply system equipped with the device of the present invention, and FIG. 2 is an enlarged sectional view of the device of the present invention. 1... High pressure pump, 2... Fuel injection nozzle, 81...
...Electric on-off valve, 82...Spool valve, 131...
・Pressure chamber, 88...Solenoid chamber, 811...Solenoid, 815...Adjuster, 815m...Adjuster hole, 821...Cylinder body, 821&...
1st relief boat, 821b... 2nd relief port, 821h... Valve dedi, 821h-1...
Cylindrical part of Parbdedi, 822...Susol, 82
3... Suffring, 824... First hydraulic chamber, 825
...Second hydraulic chamber. Patent Applicant Japan Auto Parts Research Institute Co., Ltd. Patent Application Agent Akira Aoki Patent Attorney Kazuyuki Nishidate Patent Attorney Takashi Mitsui Akira Yamaguchi Company Japan Auto Parts Research Institute

Claims (1)

[Claims] 1. A device for controlling fuel pressure in a pressure chamber in a high-pressure pump that pumps fuel to a fuel injection nozzle, the device comprising first and second relief ports for circulating fuel back to the low-pressure chamber. A cylindrical stool is movably provided in the cylinder body, and a first hydraulic chamber is provided on one side of the spool.
A second hydraulic chamber is formed on the other side and is in constant communication with the pressure chamber.
The first hydraulic pressure and the second hydraulic chamber are communicated with each other via a throttle formed in the spool, and
An electric on-off valve is provided to control the opening and closing of the first hydraulic chamber, and the stool, which operates based on the differential pressure between the first hydraulic chamber and the second hydraulic chamber, always connects the second relief port to the second hydraulic chamber. The cylinder body is biased by a spring to separate from the chamber, and the portion of the cylinder body forming the first relief port is slidable in a sealing manner between the cylindrical surfaces of the spool end and the system tool toward the first hydraulic chamber. Fuel control device installed in 2. The fuel control device according to claim 1, wherein the spring is disposed within an annular spring chamber formed between the cylinder body and the spool. 3. The fuel control device according to claim 1, in which the sealing sliding part between the cylinder body part and the spool is a labyrinth packing. 4. When the electric on-off valve closes, the first 2. The fuel control device according to claim 1, wherein the pressure receiving area of the hydraulic chamber is larger than or equal to the pressure receiving area of the second hydraulic chamber. 5. A device for controlling the fuel pressure in a pressure chamber in a high-pressure pump that pressure-feeds fuel to a fuel injection nozzle, comprising a cylinder body having first and second relief ports for returning fuel to a low-pressure chamber. , a cylindrical stool is movably provided within the cylinder body, and a first hydraulic chamber is provided on one side of the spool;
A second hydraulic chamber is formed on the other side and is in constant communication with the pressure chamber.
The first hydraulic pressure and the second hydraulic pressure chamber are communicated with each other via a throttle formed in the stool, and
An electric on-off valve is provided to control opening and closing of the first hydraulic chamber, and the second hydraulic chamber is operated by the spool, which is operated by the differential pressure between the first hydraulic chamber and the second hydraulic chamber. A cylindrical lift adjuster is provided on the opposite side of the spool, which opens and closes with respect to the port, and is sandwiched between the valve body of the solenoid valve, and a closeable lift adjustment hole is provided in the center of the adjuster to adjust the lift of the valve body. 1. A fuel control device characterized in that the fuel control device is provided with a lift adjusting means. 6. A device for controlling the fuel pressure in a pressure chamber in a high-pressure pump that pressure-feeds fuel to a fuel injection nozzle, comprising a cylinder body having first and second relief ports for circulating fuel back to the low-pressure chamber. , a cylindrical spool is movably provided within the cylinder body, a first hydraulic chamber is formed on one side of the spool, and a second hydraulic chamber that is constantly in communication with the pressure chamber is formed on the other side. The second hydraulic chamber communicates with the second hydraulic chamber through a throttle formed in the spool, and is provided with an electric on-off valve that controls opening and closing of the first relief port with respect to the first hydraulic chamber. The second hydraulic chamber is opened and closed with respect to the second relief port by the spool that moves based on the differential pressure between the chamber and the second hydraulic chamber, and a solenoid chamber is formed around the solenoid of the electromagnetic valve. A fuel control device characterized in that recirculated fuel from the second relief port is returned via the solenoid chamber.