JPH08144891A - Fuel injection pump for internal combustion engine - Google Patents

Abstract

PURPOSE: To provide a fuel injection pump for an internal combustion engine which is provided with an isobaric device needing no particular work on a delivery valve and can improve the strength of the isobaric device. CONSTITUTION: An isobaric device 40 is accommodated in an isobaric valve chamber 30 formed between a delivery valve chamber 23 and discharge path 22. While the isobaric valve device is accommodated removably in the isobaric valve chamber, it consists of a slide holder 41 provided with an open orifice 42, an isobaric valve 45 provided in the slide holder to open and close the orifice and an isobaric valve spring 48 to press the isobaric valve against the orifice. Thus, when fuel is forcibly sent, the slide holder is lifted to send the fuel to the discharge path. When a counter-flow is generated after the completion of the forcible sending, the slide holder closes the fuel path while the isobaric valve opens the orifice from which fuel is allowed to reversely flow.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection pump for a diesel engine or a gasoline engine, and relates to a constant pressure valve structure for controlling a residual pressure at the end of pressure feeding of fuel.

[0002]

2. Description of the Related Art Generally, a vertical type (Bosch type) fuel injection pump for supplying a fuel to a diesel engine or a gasoline engine has a plunger reciprocally fitted in a cylinder and a tip end surface of the plunger and the cylinder. A pump chamber is formed between the pump chamber and the inner surface of the engine, and the cam is reciprocally driven by the cam to pressurize the fuel introduced into the pump chamber and pump the fuel to the fuel injection nozzle on the engine side.

A delivery valve is provided on the downstream side of the pump chamber. When the fuel pressure in the pump chamber exceeds a predetermined pressure, the delivery valve is pushed open to supply the fuel in the pump chamber. It is adapted to be sent to the fuel injection nozzle through a pipe.

In the fuel injection nozzle, when the fuel pressure in the fuel chamber becomes equal to or higher than the valve opening pressure of the needle valve, the needle valve opens an injection hole, thereby injecting the fuel in the fuel chamber from the injection hole toward the engine. .

In such a fuel injection pump, when the pressure feeding of the fuel is completed, the fuel in the injection nozzle and the fuel supply pipe starts to flow backward (spill), and a pressure reflected wave is generated due to the closing of the fuel injection nozzle. Such a backflow of fuel and pressure reflected waves are blocked by the delivery valve.However, if the backflow speed is too fast, the closing operation of the delivery valve will not be in time, and the injection nozzle, fuel supply pipe, and delivery valve holder The pressure drops sharply. Such a sudden pressure drop causes a negative pressure in the injection nozzle, the fuel supply pipe, and the delivery valve holder, and the negative pressure causes bubbles to be generated inside the dust. Such bubbles may collapse during the next injection, causing cavitation and erosion, which may lead to abnormal injection such as asymmetric injection and secondary injection.

In order to prevent such a problem, conventionally,
It has been proposed to install an equal pressure valve device as shown in Japanese Utility Model Publication No. 5-9499. This type of equal pressure valve device is provided with an orifice in the center of a holder (equal pressure valve holder in the publication), and an equal pressure valve, which is usually a ball valve, for opening and closing the orifice is housed inside the holder. This equal pressure valve is held by a valve holder (in the publication, a spring seat), and this valve holder is pressed and urged by an equal pressure valve spring. When fuel is pumped, the equal pressure valve closes the orifice. , When fuel is sent from the surrounding path to the discharge passage and backflow occurs after the completion of pressure feeding, when a backflow pressure higher than the set pressure of the equal pressure valve spring acts, the equal pressure valve separates from the orifice and opens the orifice, and thus through the orifice. It is designed to allow backflow of fuel.

Therefore, when such a constant pressure valve device is used, the reverse flow is allowed through the orifice formed in the constant pressure valve holder when the reverse flow occurs, so that the reverse flow is regulated and the sudden pressure drop is alleviated. It is possible to suppress the generation of bubbles due to negative pressure. Therefore, abnormal injection can be prevented.

[0008]

However, since the conventional equal pressure valve device described in the above publication has a structure in which the equal pressure valve device is incorporated inside the delivery valve, a special accommodating space is processed in the delivery valve. It is necessary to complicate the structure of the delivery valve and increase the processing cost.

Further, the equal pressure valve device must be formed in a small size because it must be housed in a delivery valve having a restricted size, and therefore, the thickness of the delivery valve and the
The wall thickness of the holder must be reduced, which causes a problem that mechanical strength is reduced.

The present invention has been made in view of the above circumstances. The object of the present invention is that the delivery valve does not require any special processing, and therefore the existing delivery valve can be used as it is. The pressure valve device is intended to provide a fuel injection pump for an internal combustion engine, which is provided with an equal pressure valve device capable of ensuring sufficient mechanical strength and having improved reliability and life characteristics.

[0011]

According to a first aspect of the present invention, fuel in a pump chamber formed in a cylinder is pressurized by a plunger inserted so as to reciprocate, and the pressurized fuel is used to deliver the fuel to a delivery valve chamber. In a fuel injection pump for an internal combustion engine equipped with a constant pressure valve device that pushes the valve open to supply fuel to the engine side from the discharge passage and suppresses backflow when fuel pressure feeding is completed, between the delivery valve chamber and the discharge passage. A constant pressure valve chamber is formed in the constant pressure valve chamber, and a constant pressure valve device is housed in the constant pressure valve chamber. The constant pressure valve device is provided on the delivery valve chamber side of the constant pressure valve chamber and has a seat with a communication hole and the seat. The slide holder is slidably housed in the pressure equalizing valve chamber, forms a fuel passage between the pressure equalizing valve chamber and the inner surface of the pressure equalizing valve chamber, and has an orifice. A constant pressure valve provided inside the holder for opening and closing the orifice; a valve holder for holding the constant pressure valve; and a constant pressure valve spring for pressing the valve holder to press the constant pressure valve against the orifice, When the fuel is pressure-fed, the slide holder lifts from the seat and sends the fuel to the discharge passage through the fuel passage, and when a backflow occurs after the completion of the pressure feed, the slide holder sits on the seat and closes the fuel passage. It is characterized in that the constant pressure valve opens the orifice against the biasing force of the constant pressure valve spring and allows the backflow of fuel through this orifice.

According to a second aspect of the present invention, the delivery valve chamber, the equal pressure valve chamber and the discharge passage are formed integrally with the delivery valve holder, and the seat separates the delivery valve chamber and the equal pressure valve chamber, Moreover, this seat also serves as a spring seat for the delivery valve spring housed in the delivery valve chamber.

[0013]

According to the first aspect of the invention, when the delivery valve is pushed open by the fuel pressurized in the pump chamber, the slide holder of the equal pressure valve device is lifted from the seat, thereby discharging the fuel through the fuel passage. Can be sent to the side. When the fuel is completely pumped, the slide holder is seated on the seat to close the fuel passage, and the equal pressure valve receives the reverse flow pressure to open the orifice to allow the reverse flow of the fuel. When a backflow occurs after the end, it allows a small amount of backflow.
The backflow is regulated, but the sudden pressure drop is alleviated, and the generation of bubbles due to negative pressure can be suppressed.

Further, according to the first aspect of the present invention, since the equal pressure valve chamber is formed between the delivery valve chamber and the discharge passage, and the equal pressure valve device is configured separately from the delivery valve, the delivery valve is specially processed. The delivery valve having the existing structure which is generally used in the past can be used without the need to perform.

Since the equal pressure valve chamber is formed between the delivery valve chamber and the discharge passage, a relatively large space can be secured, and each component of the equal pressure valve device accommodated therein can be made relatively large. It is possible to improve the mechanical strength, reliability and durability.

According to the second aspect of the present invention, the delivery valve chamber, the equal pressure valve chamber and the discharge passage are formed integrally with the delivery valve holder, so that the number of parts is reduced and the delivery valve chamber and the equal pressure valve chamber are separated from each other. The partition member is a seat with which the slide holder on the side of the constant pressure valve chamber comes in and out,
Since it also serves as the spring seat of the delivery valve spring housed in the delivery valve chamber, it is possible to reduce the number of parts and simplify the structure from this point as well, and to make the injection pump compact and compact. it can.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on an embodiment shown in the drawings. FIG. 5 is a sectional view showing the whole of a vertical type (Bosch type) fuel injection pump. In FIG. 5, 1 is a pump housing. A cam shaft 2 that interlocks with a crank shaft of an engine (not shown) is provided below the pump housing 1, and a cam 3 is formed on the cam shaft 2.

A cylinder 4 is mounted in the pump housing 1, and a plunger 5 is installed in the cylinder 4.
Is reciprocatingly inserted. A pump chamber 6 is formed between the upper end of the plunger 5 and the inner surface of the upper end of the cylinder 4. The pump chamber 6 communicates with a fuel intake / exhaust port 7 formed on the side wall of the cylinder 4 when the plunger 5 descends. It is supposed to do. The fuel intake / exhaust port 7 communicates with a fuel pool 8 formed between the cylinder 4 and the pump housing 1, and the fuel pool 8 communicates with a fuel introduction passage 9 formed in the pump housing 1.

A lower spring seat 10 is connected to the lower end of the plunger 5, and a plunger spring 12 is bridged between the lower spring seat 10 and an upper spring seat 11 attached to the pump housing 1. ing. The plunger spring 12 presses the lower spring seat 10 against the tappet 13. The tappet 13 has a tappet roller 14, and the tappet roller 14 is in sliding contact with the cam 3. Therefore, when the cam 3 rotates, the plunger 5 is reciprocally driven through the tappet roller 14 and the lower spring seat 10. The reciprocating stroke of the plunger 5 is determined by the height difference of the cam 3.

The lead groove 1 is provided on the upper side surface of the plunger 5.
5 is formed. The lead groove 15 is formed by a groove formed on the outer peripheral surface of the plunger 5 so as to be inclined. When the plunger 5 is rotated about the axial center line, the position of the lead groove 15 corresponding to the fuel intake / exhaust port 7 formed in the cylinder 4 is changed, thereby controlling the fuel injection amount. That is, as the plunger 5 moves upward, the fuel in the pump chamber 6 is pressurized, and this pressurized fuel is supplied to the engine side as described later. When 15 communicates with the fuel intake / exhaust port 7, the fuel in the pump chamber 6 is returned from the lead groove 15 to the fuel reservoir 8 through the fuel intake / exhaust port 7. This stops the fuel from being pumped to the engine.

The rotation of the plunger 5 changes the timing at which the inclined lead groove 15 and the fuel intake / exhaust port 7 communicate with each other, so that the amount of fuel discharged is controlled according to the rotation angle of the plunger 5.

The lower end of the plunger 5 is engaged with the control sleeve 17. Control sleeve 17
Is rotatably attached to the outer peripheral portion of the cylinder 4, and the lower end of the control sleeve 17 and the lower end of the plunger 5 rotate integrally in the rotating direction, but when the plunger 5 reciprocates. The control sleeve 17 can move freely without restricting the movement of the plunger 5.

The control sleeve 17 has a pinion 1
8 is provided, and this pinion 18 meshes with the control rack 19. Control rack 19
Is connected to a governor (not shown) installed outside the pump housing 1, and this cab operates according to the operating conditions such as the rotational speed of the engine, thereby operating the control rack 19. Therefore, control rack 1
The movement of 9 causes the control sleeve 17 to rotate through the pinion 18, which in turn causes the plunger 5 to rotate. Therefore, the lead groove 15 is displaced relative to the fuel intake / exhaust port 7, and the fuel injection amount can be controlled.

A delivery valve holder 20 is connected to the upper end of the pump housing 1. As shown in FIG. 1, the delivery valve holder 20 is provided with a delivery valve seat 21 at the lower end. The delivery valve seat 21 has a lower end surface in close contact with the upper end surface of the cylinder 4, and a valve port 24 is opened at the center thereof.
A discharge passage 22 is provided at the upper end of the delivery valve holder 20.
Are formed. The delivery valve chamber 2 is provided between the delivery valve seat 21 and the discharge passage 22.
3 and a partition wall 31 define an equal pressure valve chamber 30 to be described later.

The delivery valve chamber 23 accommodates a delivery valve 25 and a delivery valve spring 26 for pressing the delivery valve 25. The delivery valve spring 26 has a lower end abutting against the seat portion 25a of the delivery valve 25 and an upper end abutting against the partition wall 31, and therefore the partition wall 31 also serves as a spring seat of the delivery valve spring 26.

The delivery valve 25 may be a known delivery valve that has been used conventionally, and has a seat portion 25a and a rod portion 25b, and the rod portion 25b has a plurality of radial blade portions 25c. , Radial wings 25
c are slidably inserted into the valve port 24 of the delivery valve seat 21, and the lower end of the delivery valve spring 26 is in contact with the seat portion 25a. Therefore,
The delivery valve 25 is pressed by the delivery valve spring 26 to be in close contact with the delivery valve seat 21, thereby closing the valve port 24. When the fuel pressure in the pump chamber 6 reaches or exceeds the predetermined pressure,
The delivery valve 25 is pushed by this fuel and lifted from the delivery valve seat 21 to open the valve port 24. Therefore, the fuel in the pump chamber 6 passes through the valve port 24, is delivered to the discharge passage 22 via the delivery valve chamber 23 and the equal pressure valve chamber 31.

The discharge passage 22 is connected to a fuel injection nozzle 29 on the engine side via a fuel supply pipe 28. Therefore, when the delivery valve 25 is opened, the fuel in the pump chamber 6 is pressure-fed to the fuel injection nozzle 29 on the engine side.

The delivery valve chamber 23 and the discharge passage 22
One end of the equal pressure valve chamber 30 formed between the two is communicated with the delivery valve chamber 23 through a communication hole 32 formed in the partition wall 31, and the other end is communicated with the discharge passage 22.

The partition wall 31 is fixed to the delivery valve holder 20 at a predetermined position by means such as press fitting, caulking, screwing, and pressure contact. The equal pressure valve chamber 30
The isobaric valve device 40 according to the present invention is housed in the.
Explaining the equal pressure valve device 40, reference numeral 41 denotes a slide holder, which does not have a cylindrical shape with an open lower end, and has an orifice 42 opened at the center of the upper wall. The slide holder 41 is vertically slidably fitted in the equal pressure valve chamber 30 and contacts the partition wall 31 when the slide holder 41 descends. Therefore, the partition wall 31 also serves as a seat surface on which the slide holder 41 comes in and out, that is, a seat.

Fuel passages 43 ... And 44 ... Are formed between the outer surface of the slide holder 41 and the inner surface of the equal pressure valve chamber 30. As shown in FIG. 2, the fuel passages 43 ...
Cut surfaces 43a are formed on at least one outer surface of the slide holder 41, and in the illustrated case, three cut surfaces 43a are formed by a gap formed between the cut surfaces 43a and the inner circumferential surface of the equal pressure valve chamber 30. The slide holder 41 is configured.
, Which are not formed with the cut surfaces 43a, serve as guide surfaces 43b, which are in sliding contact with the inner peripheral surface of the equal pressure valve chamber 30.

Further, as shown in FIG. 2, the other fuel passages 44 ... Also have radial grooves 44a ... formed in at least one location, three locations in the figure, on the upper surface of the slide holder 41. The grooves 44a ...
Are continuous with the cut surfaces 43a. It should be noted that stopper projections 44b ... Are formed on the upper surface of the slide holder 41 at positions other than the positions where the grooves 44a ... Are provided. These stopper projections 44b ...
When 1 is lifted by a predetermined amount (specified lift amount = h), it hits the ceiling surface of the equal pressure valve chamber 30, so that the fuel passage 44 by the grooves 44a ... Communicates the passage 43 with the discharge passage 22. I am supposed to keep it.

An equal pressure valve 45 for opening and closing the orifice 42 is housed inside the slide holder 41. The equal pressure valve 45 is a ball valve and is held by a valve holder 46. The valve holder 46 supports the equal pressure valve 45 formed of the above ball valve, and there is a gap between the slide holder 41 and the inner surface of the slide holder 41.
It is slidably accommodated in. This valve holder 46 and the spring seat 4 attached to the lower end of the slide holder 41
A constant pressure valve spring 48 is provided between the
The valve holder 46 is pushed up by the constant pressure valve spring 48. Therefore, the equal pressure valve 45 is pressed against the ceiling surface of the slide holder 41, thereby closing the orifice 42.

The spring seat 47 includes a partition wall 3
An opening 49 communicating with one communication hole 32 is formed. In addition, the spring seat 47 is the slide holder 41.
It is fixed to a predetermined position by a means such as press fitting, caulking, screwing, and pressure contact with the lower end of the.

The operation of the embodiment having such a configuration will be described. The plunger 5 reciprocated with the rotation of the cam shaft 3 sucks fuel into the pump chamber 6 when the plunger tip surface or the lead groove 15 opens the fuel intake / exhaust port 7 when descending, and the plunger tip when ascending. When the surface closes the fuel intake / exhaust port 7, the fuel in the pump chamber 6 is pressurized.

When the fuel pressure in the pump chamber 6 overcomes the spring 26 of the delivery valve 25, the delivery valve 2
5 is lifted from the delivery valve seat 21, and the fuel in the pump chamber 6 is pressure-fed to the delivery valve chamber 23 from the valve port 24. When the fuel pressure in the delivery valve chamber 23 increases, this pressure is transmitted to the isobaric valve chamber 30 through the communication hole 32 formed in the partition wall 31.

In the equal pressure valve chamber 30, fuel pressure is applied from the side of the communication hole 32, so that the equal pressure valve 45 is pressed against the ceiling surface of the slide holder 41 to close the orifice 42, so that the slide holder 41 is pushed up and the partition wall. The sheet 31 is lifted.

The slide holder 41 is the partition wall (sheet) 3
3, the fuel in the delivery valve chamber 23 is formed through the communication hole 32 of the partition wall 31 between the outer surface of the slide holder 41 and the inner surface of the equal pressure valve chamber 30, as shown in FIG. , 44, and then delivered to the discharge passage 22.

Although the stopper surface 44b formed on the upper surface of the slide holder 41 contacts the ceiling surface of the equal pressure valve chamber 30 and is stopped, the fuel passage 44 including the grooves 44a ... The fuel pressurized in the pump chamber 6 passes through the delivery valve chamber 23 and passes through the partition wall 3
It is sent out to the discharge passage 22 through the fuel passages 43, ...

This fuel is supplied to the injection nozzle 29 on the engine side through the fuel supply pipe 28. Then, in the injection nozzle 29, when the fuel pressure in the fuel chamber (not shown) becomes equal to or higher than the valve opening pressure of the needle valve, the needle valve opens an injection hole, thereby injecting the fuel in the fuel chamber toward the engine through the injection hole.

When such pumping of fuel is completed, the pump chamber 6 communicates with the intake / exhaust port 7 via the lead groove 15, so that the fuel in the injection nozzle 29 and the fuel supply pipe 28 starts to flow backward (spill). Also, a pressure reflection wave is generated due to the valve closing of the fuel injection nozzle 29. When such a reverse flow of fuel and a pressure reflected wave occur, the slide holder 41 is pushed down by the reverse flow pressure from the discharge passage 22, and the lower end is seated on the partition wall (sheet) 31, whereby the fuel passages 43, ... Is cut off.

When the reverse flow pressure is larger than the set load of the constant pressure valve spring 48, the constant pressure valve 45 receives the reverse flow pressure and is pushed down, so that the orifice 42 is opened. Therefore, the fuel flows from the discharge passage 22 to the orifice 42.
Through the communication hole 32 of the partition wall 31 to the delivery valve chamber 23.

As a result, the delivery valve 25 comes into close contact with the delivery valve seat 21 and closes the valve port 24. The reverse flow continues until the constant pressure valve 45 that receives the pressing force of the constant pressure valve spring 48 returns and comes into close contact with the slide holder 41. That is, the fuel pressure in the discharge passage 22 is equal to or less than the set load of the equal pressure valve spring 48, and therefore, the equal pressure valve 45.
When the pressure drops below the valve closing pressure of
Since 2 is closed, this pressure drop continues.

Therefore, the fuel pressure on the downstream side from the discharge passage 22 can be reduced to a predetermined pressure or lower. Since the above-mentioned backflow gradually progresses due to the throttling action of the orifice 42, the pressure in the injection nozzle 29, the fuel supply pipe 28, and the discharge passage 22 is prevented from dropping sharply, and thus the injection nozzle 29 and the fuel supply pipe 28 are prevented. Further, it is possible to prevent negative pressure from being generated in the discharge passage 22, and it is possible to prevent bubbles from being generated due to this negative pressure. As a result, abnormal injection such as asymmetrical injection or secondary injection can be prevented.

The size of the orifice 42 is appropriately selected in accordance with the degree of pressure drop and the degree of disconnection of injection. If the orifice 42 is too small, the disconnection of injection is aggravated. The effect of preventing descent cannot be expected.

According to this embodiment, the equal pressure valve chamber 30 is formed between the delivery valve chamber 23 and the discharge passage 22, and the equal pressure valve device 40 is housed in the equal pressure valve chamber 30, so that the equal pressure valve device is formed. The delivery valve 25 can be configured separately from the delivery valve 25, and the delivery valve 25 does not need to be specially processed, and the delivery valve 25 having an existing structure that has been widely used in the past can be used.

Since the constant pressure valve chamber 30 is formed between the delivery valve chamber 23 and the discharge passage 22, a relatively large space can be secured, and the constant pressure valve device 40 housed therein can be secured.
Each of the components 41 to 49 can be made relatively large. Therefore, the mechanical strength of the equal pressure valve device 40 is increased, and the reliability and durability can be improved.

Furthermore, since the delivery valve chamber 23, the equal pressure valve chamber 30 and the discharge passage 22 are integrally formed with the delivery valve holder 20, the number of parts is reduced and the conventional delivery valve holder 20 is only slightly modified. can do.

A partition wall 31 for partitioning the delivery valve chamber 23 and the constant pressure valve chamber 30 has a seat with which the slide holder 41 on the side of the constant pressure valve chamber 30 comes into contact with and separates from the delivery valve chamber 23.
Since it also serves as the spring seat of the delivery valve spring 26 accommodated in the above, the number of parts is small and the structure can be simplified also from this point.

As described above, the fuel injection pump can be made compact and compact despite the addition of the equal pressure valve device 40. The fuel passages 43, ..., 44 ...
On the outer surface of the slide holder 41, the cut surface 43a and the groove 4
Although 4a is processed, it is also possible to form grooves or the like on the inner surface of the equal pressure valve chamber 30 to form the fuel passages 43.

[0050]

As described above, according to the first aspect of the invention, when the delivery valve is pushed open by the fuel pressurized in the pump chamber during the fuel pressure feeding, the slide holder of the equal pressure valve device is lifted from the seat, Thus, the fuel can be sent to the discharge passage side through the fuel passage. When the fuel is completely pumped, the slide holder is seated on the seat to close the fuel passage, and the equal pressure valve receives the reverse flow pressure to open the orifice to allow the reverse flow of the fuel. When the backflow occurs after the end, the backflow of a small flow rate is allowed, so that the backflow is regulated, but the sudden pressure drop is alleviated, and the generation of bubbles due to the negative pressure can be suppressed.

Moreover, according to the first aspect of the present invention, since the equal pressure valve chamber is formed between the delivery valve chamber and the discharge passage and the equal pressure valve device is configured separately from the delivery valve, the delivery valve is specially processed. The delivery valve having the existing structure which is generally used in the past can be used without the need to perform.

Since the equal pressure valve chamber is formed between the delivery valve chamber and the discharge passage, a relatively large space can be secured, and the components of the equal pressure valve device housed therein can be made relatively large. It is possible to improve the mechanical strength, reliability and durability.

Further, according to the second aspect of the present invention, the delivery valve chamber, the equal pressure valve chamber and the discharge passage are integrally formed in the delivery valve holder, so that the number of parts is reduced and the delivery valve chamber and the equal pressure valve are also reduced. The partitioning member that divides the chamber doubles as the seat that the slide holder on the side of the constant pressure valve chamber contacts and separates, and the spring seat of the delivery valve spring housed in the delivery valve chamber, which also reduces the number of parts. The structure can be simplified and the injection pump can be made small and compact.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view showing an embodiment of the present invention and showing an enlarged internal structure of a delivery valve holder connected to a pump housing of a fuel injection pump.

FIG. 2 is a view of the slide holder taken along the line AA of FIG. 1 as seen from the upper surface side.

FIG. 3 is a partial cross-sectional view showing an operating state of a constant pressure valve device at the time of fuel pressure feeding of the embodiment.

FIG. 4 is a partial cross-sectional view showing an operating state of the constant pressure valve device at the time of reverse fuel flow of the embodiment.

FIG. 5 is a sectional view showing the entire fuel injection pump of the embodiment.

[Explanation of symbols]

1 ... Pump housing 3 ... Cam 4 ... Cylinder 5 ... Plunger 6 ... Pump chamber 7 ... Fuel intake / exhaust port 15 ... Lead groove 17 ... Control sleeve 18 ... Pinion 19 ... Control rack 20 ... Delivery valve holder 21 ... Delivery valve seat 22 ... Discharge Passage 23 ... Delivery valve chamber 24 ... Valve port 25 ... Delivery valve 26 ... Delivery valve spring 28 ... Fuel supply pipe 29 ... Fuel injection nozzle 30 ... Isostatic valve chamber 31 ... Partition wall (also seat and delivery valve spring seat) 32 ... Communication Hole 40 ... Equal pressure valve device 41 ... Slide holder 42 ... Orifice 43, 44 ... Fuel passage 45 ... Equal pressure valve 46 ... Valve holder 47 ... Spring seat 48 ... Equal pressure valve spring 49 ... Opening

Claims (2)

[Claims] 1. A reciprocally movable plunger is inserted into a cylinder to pressurize fuel in a pump chamber formed in the cylinder, and the pressurized fuel pushes a delivery valve provided in the delivery valve chamber to open the fuel from the discharge passage. In the fuel injection pump for an internal combustion engine, which is provided with a pressure equalizing valve device that suppresses backflow when the pressure feeding of the fuel is completed, a pressure equalizing valve chamber is formed between the delivery valve chamber and the discharge passage,
An equal pressure valve device is housed in the equal pressure valve chamber, and the equal pressure valve device is provided on the delivery valve chamber side of the equal pressure valve chamber and is capable of coming into contact with and separating from a seat having a communication hole opened and the seat. A slide holder, which is slidably accommodated in the equal pressure valve chamber, constitutes a fuel passage between the same pressure valve chamber and the inner surface of the equal pressure valve chamber, has an orifice, and is provided inside the slide holder to open and close the orifice. It is equipped with a pressure equalizing valve, a valve holder that holds this pressure equalizing valve, and a pressure equalizing valve spring that presses this valve holder and presses the pressure equalizing valve against the orifice.When the fuel is pumped, the slide holder moves from the seat. When the fuel is lifted and the fuel is sent to the discharge passage through the fuel passage, and if backflow occurs after the completion of the pressure feed, the slide holder sits on the seat to close the fuel passage, and A fuel injection pump for an internal combustion engine, wherein a valve opens an orifice against an urging force of a constant pressure valve spring and allows a reverse flow of fuel through the orifice. 2. The delivery valve chamber, the isobaric valve chamber, and the discharge passage are integrally formed in a delivery valve holder, the seat separates the delivery valve chamber and the isobaric valve chamber, and the seat, 2. The fuel injection pump for an internal combustion engine according to claim 1, which also serves as a spring seat of a delivery valve spring housed in the delivery valve chamber.