JPH0316489B2 - - Google Patents

Description

Detailed Description of the Invention Technical Field The present invention is incorporated into a part of a fuel supply system for an internal combustion engine, and is used to recirculate fuel discharged from a pump to a tank in order to stop or start fuel supply to a fuel injection nozzle. Or it relates to a fuel control device that stops this reflux.

Prior Art Conventionally, as this type of fuel control device, there was one in which a relief port for circulating fuel into a tank was controlled to open and close by a solenoid valve. However, if you try to discharge a large amount of fuel from this relief port in order to instantly stop fuel injection, for example,
Since it is necessary to increase the flow path area of the relief port, the solenoid valve must be increased in size. In other words, in order to increase the amount of lift of the valve body, it is necessary to increase the size of the solenoid and also make the part of the valve body into which the solenoid fits larger.As a result, the entire device becomes expensive and it is difficult to obtain sufficient responsiveness. This causes a problem.

OBJECTS OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to improve responsiveness and, in particular, to easily downsize the structure of the piping system.

Structure of the Invention The fuel control device of the present invention is arranged to face a pressure chamber in a high-pressure pump that pumps fuel to a fuel injection nozzle, and communicates with the pressure chamber, as well as a fuel control device for circulating fuel to a low-pressure side. a cylindrical cylinder member having first and second relief ports; a cylindrical cylinder member that is cylindrical and slidably fitted into the cylinder member; and a throttle hole formed inside that communicates with the pressure chamber through a hydraulic chamber; a spool that constantly communicates with the first relief port and that itself is configured to open and close between the pressure chamber and the second relief port; and an electrically operated valve that opens and closes the first relief port. The electrically operated valve and the spool allow the hydraulic chamber and the pressure chamber to communicate with the low pressure side, respectively, and the confluence of the first relief port and the second relief port is It is characterized in that it communicates with the pump chamber on the low pressure side through an annular relief chamber formed in a casing that accommodates the cylinder member and a drain hole formed in the high pressure pump.

Example The present invention will be explained below with reference to illustrated embodiments.

FIG. 1 shows a device already proposed by the present inventors. As the high-pressure pump 1, 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 plunger 11 of the high-pressure pump 1 is driven by an engine (not shown), and rotates and reciprocates synchronously at 1/2 rotation of the engine. The time when the first notch groove 12 of the plunger 11 is in communication with the suction port 14 of the cylinder 13 is the suction stroke,
The plunger 11 sucks fuel oil into a pressure chamber 131 formed by the cylinder 13 and the tip of the plunger 11 while moving to the left in the figure. The discharge stroke is when the second notch groove 15 of the plunger and the discharge port 16 of the cylinder 13 are electrically connected, and the plunger 11 moves fuel oil from the pressure chamber 131 to the notch groove while moving to the right in the figure. 15, and sends it out to the high pressure line 18 through the discharge port 16. 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 that is sufficiently later than the time.

The fuel in the tank is pumped through a low pressure line 17 by the feed pump 3 and supplied 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 1 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 solenoid valve 81 as an electric on-off valve and a spool valve 8 as a hydraulic on-off valve.
2.

The spool valve 82 is composed of a cylinder member 821, a spool 822, and a spring 823. The spool 822 has a cylindrical shape, and the cylinder member 821
The hydraulic chamber 8 is fitted into the inner part of the cylinder so that it can slide freely in the left and right directions in the figure.
24,825 are formed. The left hydraulic chamber 825 is connected to the pressure chamber 131, and the spool 822
Through a diaphragm 826 formed at the central axis of the
It is always in communication with the right hydraulic chamber 824. Right hydraulic chamber 8
A spring 823 is provided within the spool 24, and this spring force constantly presses the spool 822 to the left. When the hydraulic pressure in the left hydraulic chamber 825 is sufficiently larger than the hydraulic pressure in the hydraulic chamber 824, the spool 822 moves to the right against the spring 823, and the spool 822 moves to the right against the spring 823.
When the left end surface 822b of 22 overlaps a part of the annular groove 827 formed on the inner circumferential surface of the cylinder member 821, the fuel in the left hydraulic chamber 825 flows into the annular groove 82.
7 and is relieved to the drain line 71.

The right hydraulic chamber 824 is connected to the drain line 71 by the solenoid valve 81 . The solenoid valve 81 includes a solenoid 811, a valve body 812,
It is composed of a small hole 812b and a spring 813, and when the solenoid 811 is energized, the valve body 81
2 moves to the right against the spring 813, and the small hole 812b opens. When the solenoid valve 81 opens, the fuel in the hydraulic chamber 824 is relieved to the drain line 71. The solenoid 811 is energized by the computer 20 via a lead wire 814. The computer 20 is
The solenoid 811 is energized at an appropriate time and for an appropriate period according to the accelerator opening degree and pump rotational speed signals. The accelerator opening signal is transmitted by a potentiometer 21 provided on an accelerator pedal 21.
The engine phase signal for knowing the pump rotation speed and timing is provided by two signals provided in the pump casing 4.
It is transmitted by MRE (magnetoresistive element) sensors 41 and 42. The sensor 42 detects the unevenness of the gear 51 fixed to the dry shaft 5 that rotates the plunger 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 72 pulse signals per revolution to the computer 20, and the sensor 41 sends one pulse signal per revolution to the computer 20. . The computer 20 calculates the sub-injection start timing and end timing based on these signals and energizes the solenoid 811.

Next, the basic operation of the fuel control device 8 will be explained with reference to FIGS. 2a to 2c.

When the relief is stopped (at the start of injection and during the injection period), the computer 20 controls the solenoid 811
As a result, the valve body 812 is pressed to the left by the elastic force of the spring 813 and closes the small hole 812b. Therefore, all of the relief passages of the fuel control device 8 are closed, and substantially all of the fuel discharged from the high-pressure pump 1 is supplied to the injection nozzle 2 via the notch groove 15 and the high-pressure line 18 (Fig. 2a). reference).

At the start of relief (at the end of injection), the computer 20 energizes the solenoid 811, and as a result, the valve body 812 is sucked to the right and the small hole 81
Open 2b. That is, the fuel is supplied to the hydraulic chamber 82.
5. Start relief via the throttle 826, the hydraulic chamber 824, the drain line branch pipe 711, and the drain line 71 (see FIG. 2b).

When the small hole 812b opens, the spool 822
The right hydraulic chamber 82 is
The pressure inside the hydraulic chambers 825 and 824 decreases, and the spool 822 moves to the right against the force of the spring 823 in accordance with the pressure difference between the hydraulic chambers 825 and 824. When the left end surface 822b of the spool 822 and the annular groove 827 of the cylinder member 821 communicate with each other, most of the fuel is returned to the tank 7 via the hydraulic chamber 825, the annular groove 827, the branch pipe 712 of the drain line, and the drain line 71. This causes a large amount of main relief (see Figure 2c).

As described above, in this device, the spool 822 is displaced when the small hole 812b is slightly opened.
It becomes possible to instantly relieve a large amount of fuel.

Now, in the fuel control device 8 having the above configuration, when the small hole 812b opens, the fuel flows through the three branch pipes 71.
Drain line 7 via 1,712,713
1 and is refluxed to tank 7. In other words, the drain line 71 is required to return the fuel to the tank 7, and the fuel passing through the small hole 812b is routed through the branch pipe 711, and the fuel passing through the annular groove 827 is routed through the branch pipe 712 to the solenoid valve. 8
In order to send the fuel in one solenoid 811 behind the valve body 812 to the drain line 71 via the branch pipes 713, many branch pipes are required.

The device according to the present invention connects these branch pipes 711, 71
2,713 and drain line 71 are omitted,
The structure is such that the relieved fuel is returned directly into the high pressure pump 1.

FIG. 3 shows one embodiment of the present invention.
Points different from the configuration shown in the figure and FIG. 2 will be explained.

The cylinder member 821 is a cylindrical cylinder ring 8
21c, a distance piece 821d located at one end of the cylinder ring 821c, and a distance piece 821d located at the other end of the cylinder ring 821c.
It is composed of a valve body 821h that fits into the valve body 821h. The cylinder member 821 and the spool 822 are sealed by a cylinder ring 821c on the circumference and a distance piece 821d on the end surface. The reason why the cylinder member 821 is composed of a plurality of members is to facilitate polishing and lapping. Also valve body 8
The central protrusion 21h is housed in the hydraulic chamber 824 in order to minimize the volume of the hydraulic chamber 824, and a small hole 812b is bored at its tip, and this small hole 812b is formed inside. A valve body 812 for opening and closing is slidably fitted. Thus, when the small hole 812b is opened, a pressure difference quickly occurs on both sides of the restriction 826, and when the small hole 812b is closed, the pressure difference on both sides of the restriction 826 quickly becomes zero, and the pressure difference on both sides of the restriction 826 quickly becomes zero. Movement becomes faster and responsiveness improves.

The edge position of the annular groove 827 is matched with the end face position of the distance piece 821d. As a result, fuel relief is started at the same time as the spool 822 starts moving, and responsiveness is further improved.

The casing 83 accommodates and fixes the cylinder member 821 and is provided with the solenoid valve 81. The casing 83 is attached to the plunger 11 of the casing 4 of the high-pressure pump 1 via a bottomed cylindrical attachment member 828. is screwed onto the opposite surface side. An O-ring 43 is provided on the outer peripheral edge of the mounting member 828, thereby completely blocking the inside of the casing 4 from the outside. An annular projection 828b provided on the end surface of the mounting member 823 is attached to the high pressure pump 1.
in close contact with the end face of the cylinder member 13 of the pressure chamber 13
1 to the outer circumferential side. Cylinder member 13
A drain hole 44 is formed in the axial direction, and fuel leaking from between the annular projection 828b and the end face of the cylinder member 13 is pumped through the drain chamber 13b on the outer periphery of the annular projection 828b and the drain hole 44. It is returned to the room 45.

An annular groove 827 is formed between the end surface of the casing 83 and the mounting member 828 via a relief hole 827b.
A relief chamber 827c is formed which communicates with the. The relief chamber 827c is connected to the drain chamber 13b through a relief port 829 bored in the mounting member 828.
communicate with. Therefore, the annular groove 827 is connected to the relief hole 827b, the relief chamber 827c, the relief port 829, the drain chamber 13b, and the drain hole 44.
It communicates with the inside of the pump chamber 45 via.

Inside the casing 83, there is a vertical hole 821e that extends in the axial direction and communicates with the relief chamber 827c, and a vertical hole 821e located on the opposite side of the relief chamber 827c.
A horizontal hole 821f communicating with e is bored. Side hole 8
21f is sealed from the outside by driving a pin 821g and welding after processing. casing 83
A valve chamber 812d formed by the valve body 821h and the valve body 812 communicates with the side hole 821f, and therefore this valve chamber 812d
are the horizontal hole 821f, the vertical hole 821e, and the relief chamber 8.
27c, relief port 829, drain chamber 13b
It communicates with a low-pressure pump chamber 45, which is an oil reservoir, through a drain hole 44.

The valve body 812 includes a small diameter portion 812e at the tip, a sliding portion 812f at the center, and a suction portion 812g that fits into the solenoid 811. The sliding portion 812f and the suction portion 812g each have one side portion slidably in contact with the fitting hole, and the other end portion separated from the wall surface of the fitting hole. Therefore, the fuel relieved by the small hole 812b flows through the small diameter portion 812e and the sliding portion 81.
Passing through the outer circumferential side of 2f and entering the valve chamber 812d,
Furthermore, the fuel in the spring chamber 813b that accommodates the spring 813 located on the right side of the suction portion 812g can freely flow into the valve chamber 812d through the outer circumferential side of the suction portion 812f. Therefore, the fuel passing through the small hole 812b and the spring chamber 8
The fuel in 13b is returned to pump chamber 45.

As described above, in this embodiment, the relief port 829 is formed in the mounting member 828, and the pump chamber 45 is
It is constructed so that it communicates with the inside. Therefore, there is no need for drain piping outside the device, resulting in a compact structure.

In each of the above embodiments, the present invention has been explained in the case where the fuel supply is stopped, but it goes without saying that the present invention can be explained in the case where the fuel supply is started, conversely.

Effects of the Invention As described above, according to the present invention, the responsiveness is improved and the piping system is simplified because drain piping is no longer necessary.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a device already proposed by the present inventors, FIGS. 2 a, b, and c are sectional views showing various states of fuel relief in the device shown in FIG.
The figure is a sectional view showing an apparatus according to an embodiment of the present invention. 1... High pressure pump, 2... Fuel injection nozzle, 8
... Fuel control device, 81 ... Solenoid valve (electrically operated valve), 131 ... Pressure chamber, 812 ... Small hole (first relief port), 821 ... Cylinder member, 822 ... Spool, 827 ... Annular groove (second relief port).

Claims (1)

[Claims] 1 A cylindrical tube that is disposed opposite to a pressure chamber in a high-pressure pump that pumps fuel to a fuel injection nozzle, communicates with the pressure chamber, and has first and second relief ports for circulating fuel to the low-pressure side. a cylinder member having a cylindrical shape and slidably fitted into the cylinder member, and a throttle hole formed inside constantly communicating the pressure chamber and the first relief port via the hydraulic chamber; a spool itself configured to open and close between the pressure chamber and the second relief port; and an electrically operated valve that opens and closes the first relief port, the electrically operated valve and the The hydraulic chamber and the pressure chamber can each communicate with the low pressure side by a spool, and a confluence between the first relief port and the second relief port is formed in a casing that accommodates the cylinder member. A fuel control device, characterized in that the fuel control device communicates with the pump chamber on the low pressure side through an annular relief chamber and a drain hole formed in the high pressure pump.