JPH0523827Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a check valve used in a fuel injection device used in a compression-ignition internal combustion engine.

(Prior art) As this type of fuel injection device, for example,
As shown in Japanese Patent No. 88270, a unit injector is known in which a pressurizing part and an injection part are integrated. In this unit injector, fuel in a high pressure chamber is pressurized by a plunger inserted into a plunger barrel, and the fuel is sent through a high pressure fuel passage to a nozzle, from which it is injected into the cylinder of an internal combustion engine. .

(Problems to be solved by the invention) In the above conventional unit injector,
When the fuel in the high-pressure chamber is cut off, the pressure in the high-pressure fuel passage after injection decreases rapidly, sometimes causing problems such as secondary injection. Therefore,
It is conceivable to install a check valve in the high-pressure fuel passage to prevent secondary injection, but for example,
The normal check valve shown in No. 143166 consists of a valve body that can be displaced in the axial direction of the passage, and a stopper that restricts the movement of the valve body within the passage. A problem arises in that the check valve cannot be made smaller because it requires a space for arranging the stopper.

Therefore, the object of this invention is to solve the above problems and reduce the size of the check valve in the direction of displacement of the valve body, thereby making the check valve more compact.

(Means for solving the problem) The gist of this invention is that the first high-pressure fuel passage 25 communicating with the fuel pressurizing means
and a second high fuel passage 28 in communication with the injection nozzle.
In the check valve 33 of the fuel injection device provided between the first high pressure fuel passage 25 and
A ball valve body 34 is disposed in the direction of the first high pressure fuel passage.
A seat surface 35 is formed on the first high-pressure fuel passage side of the valve insertion hole 30, and a stopper 37 is formed on the side opposite to the first high-pressure fuel passage. A chuck valve of a fuel injection device has a groove 32 formed in the radial direction of an insertion hole 30, and a side of the second high-pressure fuel passage 28 opposite to the injection nozzle is connected to the groove 32.

(Function) Therefore, in the check valve, a valve insertion hole is provided on the extension of the first high pressure fuel passage, and the seat surface of the valve insertion hole is placed on the first high pressure fuel passage side opposite to the first one. The check valve has a stopper on the high-pressure fuel passage side, which eliminates the need to secure a second space in front of the second high-pressure fuel passage through a groove formed in the radial direction of the valve insertion hole. The displacement direction of the valve body can be shortened, and therefore the above object can be achieved.

(Example) Hereinafter, an example of this invention will be described with reference to the drawings.

In FIG. 3, the fuel injection device is of a unit injector type, and has a device body 1 in which a vertical hole 2 is formed, and a plunger barrel 3 is inserted into the upper part of the vertical hole 2 of the device body 1. There is. The plunger barrel 3 has its upper end closed by a plug 4 screwed into the vertical hole 2, and is fixed to the device main body 1, for example, by cold fitting.

The plunger 5 is slidably inserted into the plunger barrel 3, and the plunger barrel 3,
A high pressure chamber 6 is defined by the plug 4 and the plunger 5. This high pressure chamber 6 is
The plunger barrel 3 communicates with a fuel reservoir 8 formed around the plunger barrel 3 through a fuel intake/discharge hole 7 formed in the plunger barrel 3 . This fuel storage chamber 8
is connected to a fuel inlet 9 formed in the main body 1 of the device. Further, a well-known fuel control groove 10 is formed slightly in front of the upper end of the plunger 5 until the plunger 5 rises and the fuel intake/discharge hole 7 is closed at the upper edge of the plunger 5 and opens into the fuel control groove 10. The distance is the effective stroke, and the fuel in the high pressure chamber 6 is pressurized during this effective stroke.

Further, the lower end of the plunger 5 is connected to a roller 11.
abuts against a tapepet 12 having a
2 and the device main body 1 is an upper spring receiver 1.
3 and a lower spring receiver 14, a plunger spring 15 is elastically loaded. roller 11
A cam (not shown) is in contact with the cam, and driving force from the internal combustion engine is transmitted to the cam, so that the plunger 5 is reciprocated in cooperation with the plunger spring 15. Further, a control sleeve 16 is rotatably fitted onto the plunger barrel 3, and this control sleeve 16 engages with a face portion (not shown) formed on the plunger 5 to allow vertical movement. A control rod 17 is engaged with the control sleeve 16. Therefore, when the control sleeve 16 is rotated by the control rod 17, the plunger 5 rotates accordingly, the relative position of the fuel intake/discharge hole 7 and the fuel control groove 10 in the circumferential direction changes, and the effective stroke is changed. The injection amount is controlled by the adjustment.

The device main body 1 includes a first
A member 18 is formed to extend laterally, and a second member 19 constituting a nozzle is connected to this first member 18 via a retaining nut 20. A valve seat body 21 constituting a spacer is sandwiched between the first member 18 and the second member 19. The second member 19 is similar to a well-known one and has a needle valve (not shown), and when high-pressure fuel is supplied to the second member 19 from first and second high-pressure fuel passages 25 and 28, which will be described later. , the needle valve is opened,
Fuel is injected into the cylinder of the internal combustion engine from a nozzle hole (not shown) formed at the tip of the second member. A spring chamber 22 is formed in the first member 18, and a nozzle spring 23 is accommodated in this spring chamber 22, and the needle valve is pressed rightward in the figure by this nozzle spring 23. The spring chamber 22 is connected to the above-mentioned fuel reservoir chamber 8 through an overflow hole 24 formed in the main body 1, and the fuel leaking from the second member into the spring chamber 22 flows through the overflow hole 24 into the fuel reservoir chamber 8. Storage room 23
It is starting to return to .

The first high-pressure fuel passage 25 includes a discharge hole 26 formed in the plunger barrel 3 and having one end open to the high-pressure chamber 6, and a communication hole 27 formed in the first member 18, and a communication hole 27 formed in the first member 18. A passage 28 (shown in FIG. 1) is formed in the second member 19, and a check valve 33 is provided between the first and second high pressure fuel passages 25, 28, a specific example of which is the first
As shown in FIG.

The check valve 33 is connected to the valve seat body 21 described above.
and a spherical ball valve body 34, which is housed in a valve insertion hole 30 (formed in the direction of the first high-pressure fuel passage) formed in the valve seat body 21 and is movable. ing. This valve insertion hole 30 is
It is perpendicularly perpendicular to the end surface of the valve seat body 21, and the diameter of the end connected to the communication hole 27 is reduced to form the inlet 31 of the check valve 33. and,
A tapered seat surface 35 on which the ball valve body 34 is seated is formed following the inlet 31, and this seat surface 3
The end surface of the second member 19 facing the ball valve body 3
This constitutes a stopper 37 that restricts the movement of 4.

Further, in the end face of the valve seat body 21 on the second member 19 side, a groove 3 is formed by cutting out an arc shape from the end face.
2 is formed. This groove 32 has a groove width smaller than that of the ball valve body 34, and the vicinity of one end thereof intersects and communicates with the valve insertion hole 30. That is, the groove 32 is formed in the radial direction with respect to the valve insertion hole 30, and the groove 32 is formed in the second member 19 near the other end.
A high pressure fuel passage 28 is connected via an outlet 38 of the check valve 33.

Therefore, the check valve 33
The axes of the outlet 38 and the outlet 38 are misaligned, and the fuel led from the communication hole 27 into the check valve 33 flows through the valve insertion hole 30 to the second member 19 side, then changes direction by 90 degrees and flows through the groove 32. The fuel then changes direction again near the other end of the groove 32, reaches the outlet 38, and is sent to the second high pressure fuel passage 28.

In processing the valve seat body 21, first, a valve insertion hole 30 is formed in the valve seat body 21, and then the end face of the valve seat body 21 is notched so as to cross this valve insertion hole 30, and a groove 3 is formed in the valve seat body 21.
2, and then the ball valve body 34 is inserted into the valve insertion hole 30.

In the above configuration, the roller 11 of the tapepet 12
When driving force from the internal combustion engine is transmitted to the cam via the cam, the plunger 5 reciprocates in cooperation with the plunger spring 15. When the plunger 5 rises from the bottom dead center shown in the figure and closes the fuel intake/discharge hole 7, the high pressure chamber 6 is confined and the pressure of the fuel in the high pressure chamber 6 increases, and the high pressure fuel is transferred to the first and second The fuel is sent via high-pressure fuel passages 25, 28 to a second member 19, from which fuel is injected into the cylinders of the internal combustion engine. In this case, the ball valve body 34 of the check valve 33 is connected to the first high pressure fuel passage 2.
Since the pressure at the stopper 5 is high, the stopper 37 is pressed against the stopper 37 to be in an open state, and the flow of fuel is not obstructed.

When the plunger 5 further rises, the fuel control groove 10 of the plunger 5 and the fuel intake/discharge hole 7 of the plunger barrel 3 communicate with each other, and the fuel in the high pressure chamber 6 escapes to the fuel reservoir chamber 8 via the fuel intake/discharge hole 7, causing the fuel in the high pressure chamber The pressure of the fuel 6 suddenly decreases, and the injection of fuel from the second member 19 ends. At this time, the pressure in the first high-pressure fuel passage 25 decreases rapidly, and the ball valve body 34 is seated on the seat surface 35 due to the pressure difference with the second high-pressure fuel passage and becomes closed, thereby preventing backflow of fuel. To prevent.

(Effects of the invention) As described above, according to this invention, the first high-pressure fuel passage and the second high-pressure fuel passage are formed in the valve insertion hole of the ball valve housing and in the radial direction of the valve insertion hole. Since the stopper is provided on the side opposite to the first high-pressure fuel passage from the valve insertion hole and does not need to be secured in front of the second high-pressure fuel passage, the stopper is provided in the direction of displacement of the ball valve body. can reduce the dimensions of
This allows the check valve to be made smaller.

[Brief explanation of the drawing]

1 is a cross-sectional view taken along the - line in FIG. 2 showing the vicinity of the check valve of the fuel injection system of this invention; FIG. 2 is a plan view of the valve seat body seen from the - line direction in FIG. 1; The figure is a sectional view showing the entire fuel injection device. 18...first member, 19...second member, 2
1... Valve seat body, 25... First high pressure fuel passage, 2
8...Second high pressure fuel passage, 31...Inlet, 33
...Check valve, 34...Ball valve body, 35
...Seat surface, 37...Stopper, 38...Exit.

Claims (1)

[Scope of utility model registration request] A first high-pressure fuel passage 2 communicating with fuel pressurizing means
5 and a second high fuel passage 2 in communication with the injection nozzle.
In the check valve 33 of the fuel injection device provided between the first high pressure fuel passage 25 and
A ball valve body 34 is disposed in the direction of the first high pressure fuel passage.
A seat surface 35 is formed on the first high-pressure fuel passage side of the valve insertion hole 30, and a stopper 37 is formed on the side opposite to the first high-pressure fuel passage. A check valve for a fuel injection device, in which a groove 32 is formed in the radial direction of an insertion hole 30, and a side of the second high-pressure fuel passage 28 opposite to the injection nozzle is connected to the groove 32.