JP3228020B2 - Inner cam type fuel injection pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inner-cam type fuel injection pump, and more particularly to an inner-cam type fuel injection pump for supplying high-pressure fuel to predetermined cylinders by rotating a distribution rotor.

[0002]

2. Description of the Related Art Conventionally, various techniques relating to a fuel injection pump for pumping fuel to a diesel engine have been proposed. One of such techniques is an inner-cam type fuel injection pump as disclosed in Japanese Patent Application Laid-Open No. 62-255566. Are known.

[0003] The inner cam type fuel injection pump disclosed in the above publication is rotatably held inside a pump housing and has a cam ring formed on its inner peripheral surface with a cam ring, and is synchronized with the rotation of a diesel engine. And a plunger disposed in the plunger chamber formed in the distribution rotor and reciprocating in the plunger chamber in the radial direction along the cam ridge.

[0004] The distribution rotor has a fuel supply port which communicates with a fuel suction gallery formed in the pump housing in the suction step and supplies fuel into the plunger chamber, and a discharge passage formed in the cylinder side in the discharge step. A fuel discharge port and the like are formed to distribute and supply pressurized high-pressure fuel to each cylinder of the diesel engine.

[0005] The plunger reciprocates in the plunger chamber along the cam mountain to increase the pressure of the fuel, and the high pressure fuel is distributed to and supplied to each cylinder of the diesel engine via a fuel discharge port by the rotation of the rotor. It is configured to be.

[0006]

In the inner-cam type injection pump having the above structure, the discharge pressure of the high-pressure fuel acts on the opening of the discharge port in the discharge step, and the distribution rotor moves to the position where the opening of the discharge port is formed. To the other side.

Further, the distribution rotor of the inner cam type fuel injection pump does not have a structure in which both ends are supported, but has a so-called cantilever support structure in which only one end is supported.

Accordingly, when a large discharge pressure is applied only to the opening forming position of the discharge port provided on the peripheral surface of the distribution rotor as described above, the distribution rotor moves to the opposite side from the position where the opening is formed. It will be pressed toward the position. As a result, the distribution rotor may rotate in the cylinder in a tilted state, and therefore, seizure may occur on the rotor peripheral surface.

The present invention has been made in view of the above point, and by providing a balance port, the discharge pressure of the high-pressure fuel is applied to the opening of the discharge port as well as to the position opposite to the opening forming position. With such a configuration, it is an object to provide a fuel injection pump that prevents the wear and seizure of the outer periphery of the cam ring and the inner periphery of the housing.

[0010]

The above object can be attained by taking the following means.

According to the first aspect of the present invention, a plunger that reciprocates in a radial direction along a cam ridge formed on a cam ring is included, and the plunger is moved by rotating in synchronization with the rotation of the internal combustion engine. Pressurize the fuel,
An inner cam having a distribution rotor for distributing and supplying the pressurized high-pressure fuel to each cylinder of the internal combustion engine by connecting a discharge port formed in the rotor peripheral surface to a discharge passage formed in the cylinder at an appropriate timing. In the fuel injection pump, one end of the distribution rotor is opened on a surface opposite to an opening forming position of a discharge port formed on the peripheral surface of the rotor, and the other end is connected to the discharge port,
A balance port is provided to prevent the distribution rotor from tilting with respect to the rotor rotation axis when discharging pressurized fuel.
And the opening of the balance port is connected to the discharge port.
Characterized by being provided on the rotor tip side from the opening of
It is.

[0012]

[0013]

Each of the above means operates as follows.

According to the present invention , in the discharge step, one end is formed on the rotor circumferential surface so that the discharge port formed on the rotor circumferential surface communicates with the discharge passage formed on the cylinder. The discharge port has an opening on the opposite side to the opening forming position, and the other end communicates with the discharge port. A balance port is provided to prevent the distribution rotor from tilting with respect to the rotor rotation axis when the pressurized fuel is discharged. It is configured to be installed.

Accordingly, in the discharge step, a high discharge pressure acts on the discharge port opening. However, since the balance port also communicates with the discharge port, the discharge pressure is applied to the balance port opening on the opposite surface of the discharge port. Works.

[0016] Thus, the pressure acting on the distribution rotor is balanced on both side surfaces of the rotor and deviation of the distribution rotor in the radial direction is prevented, so that the occurrence of seizure on the peripheral surface of the rotor can be prevented.

Further , by providing the opening of the balance port closer to the rotor tip than the opening of the discharge port, it is possible to provide a counter moment substantially equal to the bending moment for the distribution rotor due to the discharge pressure of the discharge port opening.
The discharge pressure acting on the balance port opening can be reduced.

Therefore, since the opening of the balance port can be reduced, the dead volume can be suppressed from increasing by providing the balance port, high-pressure fuel injection can be performed, and cavitation is induced by providing the balance port. Can be suppressed.

[0019]

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

FIGS. 1 to 3 show a fuel injection pump 10 according to an embodiment of the present invention. FIG. 1 is a sectional view showing the overall configuration of the fuel injection pump 10, FIG. 2 is a sectional view taken along the line II-II in FIG. 1, and FIG. 3 is an enlarged sectional view showing the vicinity of the distribution rotor. .

In FIG. 1, a housing 11 is a main body of the fuel injection pump 10 and has a cam chamber 12 for accommodating various functional parts of the fuel injection pump 10 and being filled with fuel.

An overflow valve 20, a spill valve 30, a fuel recirculation valve 4
0, an accumulator 50, a constant pressure valve 60, and the like. However, more specifically, the housing 11 is composed of three parts. That is,
It is composed of a main body containing a cam ring and a drive shaft, a distribution head containing a cylinder, and a cover containing a rotation sensor.

The overflow valve 20 communicates with a predetermined position of the cam chamber 12 and is a valve provided to prevent the inside of the cam chamber 12 from being excessively pressurized. The overflow valve 20 is provided with a check valve including a ball valve 22 and a spring 24. When fuel is excessively supplied into the cam chamber 12, the excess is returned to a fuel tank (not shown).

The spill valve 30 is an electromagnetic valve that opens and closes a valve body 32 by an electromagnetic force generated by an electromagnetic coil 31.
The fuel recirculation valve 40 and the fuel suction gallery 17 described later
To a fuel leak passage (spill passage) 103 described later.

The valve element 32 of the spill valve 30 is urged upward by a spring 33, and the upper end thereof has an armature 34 for transmitting the electromagnetic force generated by the electromagnetic coil 31 and a stopper 3 urged by a spring 35.
It is regulated to 6.

On the other hand, the valve body 32 and its valve seat 37 are
2 is seated on the valve seat 37, that is, the spill valve 3
When 0 is closed, hydraulic pressure acts only on the side surface of the valve body 32, and when the valve body 32 is separated from the valve seat 37, that is, when the spill valve 30 is opened. Is configured such that hydraulic pressure also acts on the distal end of the valve body 32.

When the spill valve 30 is closed, the overflow (spill) of the pressurized fuel is stopped, and the fuel pressurized by the fuel injection pump 10 is pumped to the diesel engine. When the spill valve 30 is open, the pressurized fuel overflows (spills) into the cam chamber 12 or the fuel suction gallery 17 as described later.
Thus, the pumping of the fuel to the diesel engine is stopped.

The operation of the spill valve 30 will be described. The energization of the electromagnetic coil 31 is started and the electromagnetic coil 3
When 1 generates an electromagnetic force, the armature 34 operates to press the valve body 32 by the electromagnetic force. Therefore, the valve element 32
, The pressing force of the armature 34 and the urging force of the spring 35 both act in the valve closing direction. As a result, the valve element 32 is displaced against the urging force of the spring 33, and the spill valve 30 is closed.

On the other hand, when the pressing force of the armature 34 is extinguished by stopping the energization of the electromagnetic coil 31, the urging force of the spring 33 is displaced in the valve opening direction against the urging force of the spring 35. Spill valve 30
Is opened.

The fuel recirculation valve 40 includes the spill valve 30
Is a valve provided to reduce high-pressure fuel (spill fuel) spilled from the fuel leakage passage (spill passage) 103 to a predetermined pressure and to return the fuel to the fuel tank when the valve is opened. And a check valve including a ball valve 42 and a spring 44.

The accumulator 50 is provided to absorb the fuel pressure pulsation in the fuel suction gallery 17. The accumulator 50 is connected to the fuel chamber 5 communicating with the fuel suction gallery 17 through the communication passage 56.
7 includes a piston 52 that is displaced in response to a pressure change, and a spring 54 that biases the piston 52.

The constant pressure valve 60 is a valve provided between a discharge passage 102 in the housing 11 described later and a fuel injection valve (not shown) provided in each cylinder of the diesel engine.
When the internal pressure of the fuel cell 2 exceeds a predetermined pressure and becomes high, the fuel is circulated toward the fuel injection valve at that pressure. It has the function of keeping pressure. By providing this constant pressure valve 60,
The fuel pressure in the pipe from the constant pressure valve 60 to be described later to the fuel injection valve of the diesel engine can be kept constant at any time other than during the pressure feeding.

In the cam chamber 12 of the housing 11,
A drive shaft 70 that rotates at half the rotation speed of the crankshaft of the diesel engine, and a vane-type fuel feed pump (hereinafter simply referred to as a feed pump) 80 that feeds fuel using the rotational force of the drive shaft 70 as a drive source. Rotor 90 and distribution rotor 9 rotating together with the drive shaft 70
The cylinder 100 into which the small-diameter portion 0 is inserted, the cam ring 110 surrounding the outer periphery of the large-diameter portion of the distribution rotor 90, and the like are incorporated.

The drive shaft 70 is rotatably supported in the housing 11 by a bush 13 provided near an end of the housing 11 and a bearing 14 provided inside the housing 11. Further, fuel is supplied to the bush 13 as lubricating oil in order to reduce sliding resistance. Further, an oil seal 18 is provided at an end of the drive shaft 70 connected to the diesel engine, and an oil passage 16 is provided for communicating the fuel inlet 15 and the bush 13.

At a predetermined position of the drive shaft 70, a pulser 120 having a plurality of projections 121 formed at predetermined intervals on the outer periphery thereof is provided.
Fixed to 10 is a rotation angle sensor 122 that converts the approach / separation of the projection 121 of the pulsar 120 that rotates with the drive shaft 70 into a pulse signal. By fixing the rotation angle sensor 122 to the cam ring 110 in this manner, an engine rotation signal (NE signal) can be generated at a constant timing with respect to the plunger lift regardless of the control operation of the timer device 130-described later. Can be.

The feed pump 80 is a vane pump having an outer wall 81 fixed to the housing 11 and a rotor 83 having a plurality of vanes 82. That is, the fuel sucked in from the suction port 84 provided in communication with the fuel inlet 15 is pressurized by the vanes 82 with the rotation of the rotor 83 and discharged from the fuel discharge port 85 provided in a predetermined position. .

The distribution rotor 90 is rotatably mounted in the cylinder hole 100a of the cylinder 100 in a liquid-tight manner while being engaged with the drive shaft 70. Therefore, the cylinder hole 100
“a” also functions as a bearing that rotatably supports the distribution rotor 90.

The distribution rotor 90 has a pump chamber (pressurizing chamber) 91 in a large diameter portion thereof, a communication passage 104 having one end thereof communicating with the pump chamber (pressurizing chamber) 91 in a small diameter portion thereof, and a discharge step. The discharge port 94 connects the pump chamber 91 and the fuel discharge port 93 via the communication path 104 at the same time, and the fuel suction port 92 and the pump chamber 91 via the communication path 104 during the suction process.
And a balance port 105 which is a main part of the present invention.

The pump chamber 91 has a distribution rotor 90.
A plurality of plungers (four in this embodiment) 96a to 96d that can slide in a liquid-tight manner in the radial direction are inserted.
Further, an annular groove 97 provided around the outer periphery of the distribution rotor 90 at a position offset in the axial direction is communicated with the fuel discharge port 93. The fuel outlet 93, the fuel inlet 92, and the annular groove 97 are connected to the distribution rotor 9
0 is formed on the peripheral surface of the rotor.

On the other hand, the cylinder 100 has a fuel supply passage 101 communicating the fuel suction gallery 17 with the inner periphery of the cylinder 100, one end of which communicates with the constant pressure valve 60 on the outer periphery, and the other end of the cylinder 100. A plurality of discharge passages 102 are provided on the inner periphery. Note that the fuel suction gallery 17 is configured to communicate with the fuel discharge port 85 of the feed pump 80 via an external pipe (not shown).

Here, the fuel supply passage 101 and the discharge passage 102 are provided in a plurality corresponding to the number of cylinders of the diesel engine, respectively, and the distribution rotor 90 rotates in synchronization with the rotation angle of the diesel engine. At this time, the fuel suction gallery 17 is connected to the fuel inlet 9 of the distribution rotor 90 in the suction process in accordance with the rotation angle of the diesel engine.
The fuel discharge port 93 communicates with a constant pressure valve 60 disposed in a specific cylinder in a discharge step.

The cylinder 100 has a fuel leakage passage (spill passage) 103 communicating with the annular groove 97 provided in the distribution rotor 90 and the spill valve 30 as described above.
Is provided. Here, the annular groove 97 is provided in the distribution rotor 9.
0, the annular groove 97
And the spill valve 30 are always in communication regardless of the rotation angle of the distribution rotor 90.

Next, the configuration near the pump chamber 91 will be described with reference to FIG. 2, which corresponds to the II-II section in FIG.

The fuel injection pump 10 of the present embodiment has four plungers 96 a to 96 d inserted into the distribution rotor 90.
Is driven by a cam provided on the cam ring 110 to increase the pressure of the fuel. The fuel pump 10 according to the present embodiment is compatible with a six-cylinder internal combustion engine.
Therefore, the cam ring 110 is provided with six cam ridges 110a to 110f at equal intervals as shown in FIG. Further, the positions of the four plungers 96a to 96d are designed so that lifts are simultaneously generated in all the plungers 96a to 96d. That is, the plunger 96
a to 96d perform a compression stroke of sliding toward the central axis of the distribution rotor 90 when passing through the cam lobes 110a to 110f, and sliding toward the outside of the distribution rotor 90 after passing through the cam lobes 110a to 110f. Perform a moving suction stroke.

The cam ridges 110a-11 of the cam ring 110 are provided at the outer peripheral end of each of the plungers 96a-96d.
0f to the roller shoes 98a to 98d to smoothly transmit the cam lift to the plungers 96a to 96d.
98d and rollers 99a to 99d gripped by the roller shoes 98a to 98d.

Therefore, when the distribution rotor 90 rotates inside the cam ring 110, the plungers 96a to 96d make six reciprocating movements while the distribution rotor 90 makes one rotation, and the reciprocating movement causes the plunger 96a to 96d to move inside the pump chamber 91. Is pressurized, the fuel is boosted six times at equal rotation angles while the distribution rotor 90 makes one rotation, that is, while the internal combustion engine makes two rotations.

At this time, the fuel supply passage 101 and the fuel inlet 92 shown in FIG. 1 are configured to communicate with each other in a situation where no cam lift is provided to the plungers 96a to 96d. Further, the discharge passage 102 and the fuel discharge port 93 are
It is configured to communicate with the plungers 96a to 96d immediately before a lift occurs.

Therefore, with the rotation of the distribution rotor 90,
When one of the fuel supply passages 101 communicates with the fuel inlet 92, the plungers 96a to 96d
Due to the centrifugal force generated by the rotation of the fuel pump and the fuel pressure supplied from the feed pump 80, the fuel in the fuel suction gallery 17 is supplied to the fuel supply passage 101, the fuel suction port 92, and the communication passage 104.
Is sucked into the pump chamber 91 through the suction port (suction step).

Then, the communication between the fuel supply passage 101 and the fuel inlet 92 is cut off, and then the discharge passage 102
When the lift occurs in the plungers 96a to 96d in a state where the fuel and the fuel discharge port 93 communicate with each other via the discharge port 104, the high-pressure fuel pressurized in the pump chamber 91 is presumed that the spill valve 30 is closed. High-pressure fuel is supplied to the constant pressure valve 60 via the communication passage 104, the discharge port 94, the fuel discharge port 93, and the discharge passage 102 (discharge step).

On the other hand, when the above-mentioned spill valve 30 is opened when the fuel is pressurized by the plungers 96a to 96d, the fuel pumped from the pump chamber 91 is supplied via the spill valve 30 to the fuel intake gallery 17, the fuel The fuel is returned to a tank or the like, and the supply of high-pressure fuel to each cylinder of the diesel engine is stopped.

That is, the timing at which the spill valve 30 is switched from the open state to the closed state is controlled to control the fuel injection start timing, and the timing at which the spill valve 30 is opened is controlled to control the fuel injection end timing. It becomes possible to control well. As described above, by controlling the fuel injection timing by performing the opening / closing control of the spill valve 30, the fuel injection amount control can be performed with high accuracy.
It is possible to operate the diesel engine in a state most suitable for the operating state.

When the spill valve 30 is used to spill high-pressure fuel, each port 9 provided in the distribution rotor 90 is provided by the inertia effect of the fuel during spill.
In some cases, the internal pressure at 4, 95 becomes negative pressure. When the internal pressures of these ports 94 and 95 become negative pressure, the relationship between the strokes of the plungers 96a to 96d and the amount of pumped fuel is changed, and the control accuracy of the fuel injection amount is deteriorated.

In the present embodiment, a part of the fuel spilled through the spill valve 30 is returned to the fuel suction gallery 17 and the accumulator 50 is provided in communication with the fuel suction gallery 17. This is for effective removal. With this configuration, even if excessive fuel overflow occurs due to the inertial effect during fuel spill, a part of the fuel overflow acts to increase the internal pressure of the fuel suction gallery 17, and the spill fuel is further recirculated. The pulsation of the internal pressure due to this is appropriately absorbed by the accumulator 50, so that a sufficient amount of fuel can be stably sucked in the next fuel suction.

Further, by circulating a part of the fuel to be spilled back to the suction gallery 17, spilled fuel is supplied into the pump chamber 91 in addition to the fuel from the feed pump 80. Even at this time, the fuel supply into the pump chamber 91 can be reliably performed.

Next, the timer device 130 will be described.

The fuel injection pump 10 of the present embodiment has a timer device 130 for changing the fixed angle of the cam ring 110 with respect to the housing 11. That is, the cam ring 110 is rotatably attached to the housing 11, and as shown in FIG.
It is fixed to a rod 133 sandwiched between 31 and 132.

Here, the timer pistons 131 and 132
Is a timer housing 13 constituting the timer device 130.
0a is a piston slidably inserted into the inside of Oa. In the timer housing 130a, a high-pressure chamber 134 communicating with the fuel discharge port 85 of the feed pump 80 is provided on the right side of the timer piston 131.
A low pressure chamber 135 communicating with the fuel suction port 84 of the feed pump 80 is formed on the left side of the feed pump 80.

A spring 136 for urging the timer piston 132 rightward in FIG. 2 is provided in the low-pressure chamber 135. The high-pressure chamber 134 and the low-pressure chamber 135 are connected to the solenoid valve (timing control) shown in FIG. The connection is made by an external pipe whose conduction is controlled by a valve (140). In this case, the timer pistons 131 and 132 are displaced left and right in the figure according to the pressure difference between the high pressure chamber 134 and the low pressure chamber 135, and accordingly, the rod 133 sandwiched between the timer pistons 131 and 132 is also urged right and left. The cam ring 110 is rotated by the urging force. Further, in the present embodiment, the opening and closing valve of the timing control valve 140 is duty-controlled so that the cam ring 110
Is controlled to a desired rotation angle.

With this configuration, the distribution rotor 90
, That is, the lift characteristics of the plungers 96a to 96d with respect to the rotation angle of the diesel engine can be changed, so that the degree of freedom regarding the fuel injection timing control can be further increased, and the fuel excellent in controllability can be obtained. An injection pump will be realized.

As described above, the timer device 130 changes the lift characteristics of the plungers 96a to 96d by rotating the cam ring 110 in the housing 11 using the timing control valve 140, and controls the injection timing. Configuration. For this reason,
A predetermined clearance is provided between the outer peripheral surface of the cam ring 110 and the inner peripheral surface of the housing 11 opposed to the cam ring 110 (because the clearance is fine, it does not appear in the drawing). The fuel is supplied from the cam chamber 12. The fuel supplied into the clearance functions as a lubricating oil.

Next, the balance port 105 which is a main part of the present invention will be described mainly with reference to FIGS. FIG. 4 shows the distribution rotor 90, and FIG. 5 is a vector diagram showing the force acting on the distribution rotor 90.

As described above, the balance port 105 is disposed on the distribution rotor 90, and one end of the balance port 105 is connected to the pump chamber 91 and the discharge port 94 via the communication passage 104. Therefore, in a state where the fuel injection pump 10 is in the discharge step, the fuel suction port 92 is closed by the cylinder 100 with the rotation of the distribution rotor 90, and the discharge port 94 is in communication with the fuel discharge port 93, the plunger 96a
The high-pressure fuel pressurized in the pump chamber 91 by .about.96d is also introduced into the balance port 105. That is, in the discharge step, high-pressure fuel is introduced into both the discharge port 94 and the balance port 105.

Attention is paid to the opening 105a on the cylinder side of the balance port 105.
5a is formed on the surface opposite to the formation position of the opening of the discharge port 94 formed on the rotor peripheral surface (that is, the position of the fuel discharge port 93). That is, the opening 105 a of the balance port 105 and the opening (fuel outlet 93) of the discharge port 94 are configured to be radially opposed to the central axis of the distribution rotor 90 .

Here, the state where the fuel injection pump 10 is in the discharge step and high-pressure fuel is introduced into the discharge port 94 and the balance port 105 from the pump chamber 91 through the communication passage 104 will be considered.

The pressure of the high-pressure fuel pressurized in the pump chamber 91 by the plungers 96a to 96d is, for example, 1000
It is a very large pressure of Pa. When such high-pressure fuel is applied to the fuel discharge port 93 communicating with the discharge port 94, a force indicated by an arrow F1 in FIGS. 4 and 5, for example, acts on the distribution rotor 90 due to the fuel pressure. Therefore, the distribution rotor 90 is pressed against the cylinder 100 with the force indicated by the dashed arrow F1 ′ due to the reaction of the force indicated by the arrow F1.

In the conventional configuration in which the balance port 105 is not provided, the distribution rotor 90 is pressed against the cylinder 100 by the force indicated by the arrow F1 ', and the distribution rotor 90 is inclined, so that the distribution rotor 90 is inclined between the distribution rotor 90 and the cylinder 100. Could cause burn-in.

However, in the configuration according to the present embodiment, the distribution rotor 90 is provided with the balance port 105, and the opening 105a of the distribution rotor 90 is positioned with respect to the position where the opening of the discharge port 94 (the fuel discharge port 93) is formed. It is configured to be formed at the opposite position. Therefore, the balance port 10
5, the distribution rotor 90 is introduced.
, A force indicated by an arrow F2 in FIGS. 4 and 5 acts, for example. Therefore, the distribution rotor 90 is pressed against the cylinder 100 with the force indicated by the dashed arrow F2 ′ due to the reaction of the force indicated by the arrow F2.

That is, by providing the balance port 105, two forces F in opposite directions are applied to the distribution rotor 90.
1 and F2 act.

As shown in FIG. 5, when the rotation center position of the distribution rotor 90 is indicated by A, this rotation center position A
The distance r from the rotation center position A to the position at which the opening 105a of the balance port 105 is formed, relative to the distance r from the position r to the position at which the opening (fuel discharge port 93) of the discharge port 94 is formed.
Is configured to be long (R> r). That is, the opening 105 a of the balance port 105 is connected to the discharge port 9.
4 is provided on the rotor tip side from the opening (fuel discharge port 93).

Now, in order to prevent the distribution rotor 90 from tilting, the clockwise rotation moment about the rotation center position A and the counterclockwise moment may be balanced. The rotational moment acting on the distribution rotor 90 by the above-mentioned forces F1 and F2 has a clockwise rotational moment M1 represented by M1 = F1 × r, and a counterclockwise moment M2 represented by M2 = F2 × R. Therefore, in order to prevent the distribution rotor 90 from tilting, it is necessary to set the moments M1 and M2 equal. Specifically, it is necessary to satisfy the following expression (1).

[0071]

M1 = M2∴F1 × r = F2 × R (1) In the present embodiment, the distances R and R are set so as to satisfy the above equation (1).
The dimension of r is selected. As described above, the clockwise rotation moment M1 and the counterclockwise moment M2 are balanced, so that even if high-pressure fuel is applied to each opening, the distribution rotor 90 does not tilt, and the distribution rotor 90 does not tilt. The fuel pressure acting on the rotor 90 is balanced on both sides of the rotor, and the distribution rotor 90 is prevented from being displaced in the radial direction, so that seizure on the rotor peripheral surface can be prevented.

On the other hand, in the present embodiment, as described above, the distances R and r from the rotation center position A to the respective openings are R> R.
r. Accordingly, by providing the opening 105a of the balance port 105 on the rotor tip side from the opening of the discharge port 94 (fuel discharge port 93), the opening of the discharge port 94 (fuel discharge port 93) is provided.
Opening 1 of balance port 105 against force F1 acting on
05a can be reduced (F1>
F2).

As described above, since the force F2 acting on the opening 105a of the balance port 105 can be reduced, the diameter of the opening 105a of the balance port 105 (this is equivalent to the capacity of the balance port 105).
Can be reduced. As described above, in the discharge step, the high-pressure fuel is also introduced into the balance port 105, but the high-pressure fuel introduced into the balance port 105 is not supplied to the diesel engine. It is desirable that the capacity of the balance port 105 is small.

Therefore, in the configuration of the present embodiment as described above, since the diameter (capacity) of the opening 105a of the balance port 105 can be reduced, the expansion of the dead volume due to the provision of the balance port 105 is suppressed. As a result, high-pressure fuel injection can be performed, and cavitation induced by providing the balance port 105 can be suppressed.

In the above-described embodiment, a configuration in which one balance port 105 is provided in the distribution rotor 90 has been described. However, a configuration in which a plurality of balance ports 105 are provided depending on other ports and the like may be employed. Also in this case, it is of course necessary to balance the rotational moment generated by the force acting on the opening of the discharge port 94 with the rotational moment exerted by providing the balance port.

[0076]

As described above, according to the present invention, the following various effects can be obtained.

According to the present invention, a high discharge pressure acts on the discharge port opening in the discharge step, but the balance port is also communicated with the discharge port. The discharge pressure also acts. For this reason, the pressure acting on the distribution rotor is balanced on both side surfaces of the rotor, and the radial displacement of the distribution rotor is prevented, so that the occurrence of seizure on the peripheral surface of the rotor can be prevented.

Further, since the opening of the balance port can be reduced, the expansion of the dead volume due to the provision of the balance port can be suppressed, high-pressure fuel injection becomes possible, and cavitation is induced by providing the balance port. Can be suppressed.

[Brief description of the drawings]

FIG. 1 is a front sectional view showing the entire configuration of a fuel injection pump according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along the line II-II in FIG.

FIG. 3 is an enlarged sectional view showing the vicinity of a distribution rotor.

FIG. 4 is a sectional view showing a distribution rotor taken out therefrom.

FIG. 5 is a vector diagram showing a force acting on a distribution rotor.

[Explanation of symbols]

 Reference Signs List 10 fuel injection pump 11 housing 12 cam chamber 17 fuel suction gallery 20 overflow valve 30 spill valve 40 fuel recirculation valve 50 accumulator 60 constant pressure valve 70 drive shaft 80 feed pump 85 fuel discharge port 90 distribution rotor 91 pump chamber 92 fuel suction port 93 fuel Projection port 94 Discharge port 95 Suction port 96a-96d Plunger 97 Annular groove 100 Cylinder 101 Fuel supply port 102 Discharge passage 103 Fuel spill passage 110 Cam ring 110a-110f Cam peak 120 Pulser 122 Rotation angle sensor 130 Timer device 131, 132 Timer piston 140 Timing control valve

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F02M 41/14 340 F02M 41/14 350 F02M 41/14 360 F02M 41/12 360

Claims (1)

(57) [Claims] 1. Along a cam ridge formed on a cam ring
It contains a plunger that reciprocates in the radial direction,
The plunger rotates by rotating in synchronization with the rotation of the engine.
To pressurize the fuel and form it on the peripheral surface of the rotor.
Formed discharge port in cylinder at appropriate timing
The above-mentioned pressurized by communicating with the discharge passage
Distribution row for supplying high-pressure fuel to each cylinder of the internal combustion engine
An inner-cam type fuel injection pump having a rotor,At the tip ofAn opening of the discharge port having one end formed on the peripheral surface of the rotor;
Open on the opposite side to the forming position, the other end is the discharge port
And is connected to the
To prevent the distribution rotor from tilting with respect to the rotor rotation axis.
A balance portAnd The opening of the balance port is connected to the opening of the discharge port.
It is characterized by being provided on the rotor tip side from the mouth Inner
Cam type fuel injection pump.