JPH0849618A - Fuel injection pump - Google Patents

Abstract

(57) [Summary] [PROBLEMS] An object of the present invention is to provide a fuel injection pump configured to increase a resistance moment acting on an end portion of a roller to suppress a skew motion of the roller. [Structure] The rotor 90 of the fuel injection pump 10 is rotatably inserted in the housing 11 so as to extend on the same axis as the drive shaft 70. Guide hole 10 of rotor 90
The plunger 98 inserted into the roller holder 5 holds the roller 99 sliding on the cam of the cam ring 110.
The fuel is sucked into the pump chamber 91 to be pressurized by the reciprocating movement of. A groove 99D is provided at the center of the outer periphery of the roller 99, and the resistance force due to the surface pressure of the oil film on the cam surface 110A increases to act on the roller halves 99A and 99B. Laura 9
When the skew movement of 9 occurs, the resistance moment acting on the end portion of the roller 99 increases, and the skew movement is suppressed.

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,
Particularly, it relates to a fuel injection pump suitable for a fuel injection pump of a diesel engine.

[0002]

2. Description of the Related Art An inner cam type distribution type fuel injection pump has been known as a type of fuel injection pump for a diesel engine. This type of fuel injection pump includes a cam ring having a cam surface on the inner peripheral surface thereof and a cam ring provided slidably in the inside of the cam ring in the radial direction, as described in, for example, Japanese Patent Application Laid-Open No. 1-134063. A roller shoe (roller holding member) that rotatably holds a cylindrical roller that rolls on the cam surface, a rotor that is rotationally driven inside the roller shoe, and a roller shoe that is slidable in the radial direction of the rotor. And a plunger driven in a direction in which fuel is sucked or discharged by the sliding movement in the radial direction.

In this fuel injection pump, the rotor is driven to rotate, and the roller held by the roller shoe rolls on the cam surface of the cam ring, and the plunger inserted into the rotor is rolled according to the cam shape. The pressured fuel is injected into the combustion chamber of the engine by being reciprocated by being pressed by the shoe.

Further, although the plunger is formed in a cylindrical shape, the roller shoe is formed in a substantially rectangular parallelepiped to prevent rotation. Further, a slight clearance is provided between the side surface of the roller shoe and the rectangular guide hole into which the roller shoe is inserted so that the roller shoe and the plunger can slide in the radial direction of the rotor according to the cam shape of the cam ring. Therefore, a slight clearance is also provided between the outer circumference of the plunger and the guide hole into which the plunger is inserted.

Fuel (light oil) is supplied to the surfaces of the sliding portions of the rollers, roller shoes, and plungers, and an oil film of this fuel lubricates the sliding portions.

[0006]

In the above fuel injection pump, the oil film of the fuel is formed on the surfaces of the cam surfaces of the roller and the cam ring as described above, and the oil film of the fuel is elastic fluid lubricated (Elastohydrodynamic Lubrica).
function). The roller is in rolling contact with the cam surface of the cam ring, and becomes a planetary roller with respect to the cam ring and revolves while rotating on its axis.

Further, when the roller normally rolls on the cam surface, the roller and the cam surface are basically in linear contact, and the pressure distribution at the contact portion acts uniformly in the longitudinal direction. Become. The pressure distribution in the rolling direction of the roller is a typical elastohydrodynamic lubrication pressure distribution.

When the roller rolls on the cam surface of the cam ring, for example, when the wall surface of the rotor facing both ends of the roller is bent or the rotor swings around due to the clearance between the input shaft of the rotor and the bearing. As described above, the roller rolling on the cam surface is inclined.

As described above, when the roller is inclined with respect to the axis, the displacement amount (velocity) in the roller advancing direction changes between the one end and the other end of the roller in the plane along the cam surface (hereinafter referred to as "skew motion"). Say) occurs. At this time, the roller is pressed against the cam surface, and surface pressure is generated on the oil film formed at the contact portion between the roller and the cam surface. Since the roller rolls on the cam surface, a frictional force is generated according to the magnitude of the surface pressure, so that the surface pressure at the contact portion between the roller and the cam surface becomes resistance to the progress of the roller.

Here, assuming a case where an extra force in the traveling direction acts on a portion other than the center of the roller (for example, the roller end portion), the roller end portion to which the extra force acts moves larger than the other end. That is, a moment is generated with the point at which the above-mentioned extra force is applied as the force point with the axis of the roller as the line of action.
This moment causes the above-mentioned skew movement of the roller.

When the center of rotation of the roller shoe that holds the roller and the axis of the plunger coincide with each other, the roller shoe rotates in the same direction and the plunger also rotates, even if the above skew motion occurs. There is no problem because it will be done. However, when the rotation center of the roller shoe that holds the roller and the axis of the plunger do not match, the roller shoe that holds the roller rotates in the same direction, and the end portion of the plunger that abuts the roller shoe. Receives the rotational force of the roller shoe (force in the radial direction of the plunger), and the plunger tilts with respect to the axis (radial direction of the rotor).

Since the center of rotation of the roller shoe and the axial center of the plunger are often deviated from each other, when the turning force of the roller shoe acts only on the end of the plunger with which the roller shoe abuts, the plunger moves toward the rotor. Tilt in the guide hole. Furthermore, when the axial pressing force (discharging direction force) is applied by the cam surface while the plunger is tilted, a moment with the axis as the line of action acts on the plunger,
The edge portion of the plunger may come into contact with the inner wall of the guide hole to cause seizure or pitting (local hole).

Therefore, the present invention has been made in view of the above points, and an object thereof is to prevent the plunger from becoming inoperable by returning the roller to a normal horizontal state even if the roller makes a skew motion. .

[0014]

SUMMARY OF THE INVENTION According to the present invention, a cam ring having a cam on its inner peripheral surface, a rotor rotatably driven by a drive shaft, and a plunger inserted in a guide hole bored in the radial direction of the rotor. And a roller holding member that abuts on the end of the plunger and is slidable in the radial direction of the rotor together with the plunger, and rotatably held by the roller holding member to roll on the cam surface of the cam ring. A fuel injection pump that has a roller and pressurizes the fuel by the discharge operation of the plunger as the rotor is rotationally driven to supply the fuel to the engine, in at least one of the outer periphery of the center of the roller or the cam surface. It is characterized in that a groove extending in the circumferential direction is formed.

[0015]

Since a groove extending in the circumferential direction is formed on at least one of the outer periphery of the center portion of the roller or the cam surface, the resistance force to the roller acting on the oil film interposed between the roller and the cam surface is exerted on the roller. Grows at the edges. Therefore, the moment of resistance against the skew movement of the roller becomes large, which suppresses the skew movement of the roller and stabilizes the roller in a normal state.

[0016]

1 is a front sectional view showing the overall structure of a fuel injection pump 10 according to an embodiment of the present invention.

In the figure, a housing 11 is a main body of the fuel injection pump 10, and inside thereof, a fuel chamber 12 for accommodating each functional component of the fuel injection pump 10 and filled with fuel is provided.

The housing 11 also has an overflow valve 2 which communicates with a predetermined position of the fuel chamber 12.
0, a spill valve 30, a fuel recirculation valve 40, an accumulator 50, and a constant pressure valve 60.

The overflow valve 20 is provided in the fuel chamber 12
The valve is a valve that prevents the internal pressure from becoming excessive, and is provided with a check valve including a ball valve 22 and a spring 24. When the fuel is excessively supplied into the fuel chamber 12, the excessive amount is supplied to the fuel tank ( Reflux (not shown). In this embodiment, the valve opening pressure is set to about 0.8 kg / cm ² .

The spill valve 30 is an electromagnetic valve that opens and closes the valve element 32 by the electromagnetic force generated by the electromagnetic coil 31,
A fuel recirculation valve 40 and a fuel intake gallery 17 described later.
And controlling electrical connection with a fuel leakage passage 103 described later.

The valve body 32 of the spill valve 30 is urged upward by a spring 33, and its upper end is urged by a rod 34 for transmitting the electromagnetic force generated by the electromagnetic coil 31 and a spring 35. Stopper 3
It is regulated by 6.

On the other hand, the valve element 32 and its valve seat 37 are
When 2 is seated on the valve seat 37, that is, when the spill valve 30 is closed, hydraulic pressure acts only on the side surface of the valve body 32, and the valve body 32 separates from the valve seat 37. When the spill valve 30 is open, the hydraulic pressure is also applied to the tip of the valve element 32.

That is, when the electromagnetic coil 31 generates an electromagnetic force and the rod 34 presses the valve element 32, the pressing force of the rod 34 and the urging force of the spring 35 act on the valve element 32 in the valve closing direction. As a result, the valve body 32 is displaced against the biasing force of the spring 33, and the spill valve 30 is closed.

When the pressing force of the rod 34 disappears, the urging force of the spring 33 displaces the valve body 32 in the valve opening direction against the urging force of the spring 35, and the spill valve 30 is opened. At this time, since a hydraulic pressure that presses the valve body 32 in the valve opening direction acts on the tip of the valve body 32, the higher the hydraulic pressure is, the greater the degree of opening of the spill valve 30 is secured.

The fuel recirculation valve 40 is the spill valve 30.
This valve is provided to appropriately depressurize the fuel leaked from the fuel leak passage when the valve is opened and to recirculate it to the fuel tank. Like the overflow valve 20 described above, it is a reverse valve including a ball valve 42 and a spring 44. It consists of a stop valve.

Further, the accumulator 50 is arranged to absorb the pulsation of the fuel pressure in the fuel intake gallery 17, and the piston 52 is displaced according to the pressure fluctuation of the fuel chamber communicating with the fuel intake gallery 17. , And a spring 54 for urging the piston 52.

The constant pressure valve 60 is a valve provided between a fuel outflow port 102 in the housing 11 described later and a fuel injection valve provided in each cylinder of the internal combustion engine. The internal pressure of the fuel outflow port 102 is When the pressure exceeds a predetermined pressure and becomes high, the fuel flows toward the fuel injection valve at that pressure, and the fuel outflow port 10
It has a function of keeping the pressure on the fuel injection valve side at a predetermined pressure even when the internal pressure of 2 becomes equal to or lower than the predetermined pressure.

In the fuel chamber 12 of the housing 11,
A drive shaft 70 that rotates at half the rotational speed of a crankshaft of an internal combustion engine, and a vane 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. , Drive shaft 70
A rotor 90 that rotates together with the rotor 90, a cylinder 100 into which the small diameter portion of the rotor 90 is inserted, and a cam ring 110 that surrounds the outer periphery of the large diameter portion of the rotor 90 are incorporated.

The drive shaft 70 is rotatably held with respect to the housing 11 by a bush 13 arranged near the end of the housing 11 and a bearing 14 arranged inside the housing 11. Where bush 13
In order to reduce the sliding resistance, fuel is supplied, and an oil seal 18 is provided at the end portion thereof, and an oil passage 16 is provided to connect the fuel inlet 15 and the bush 13. .

Here, a pulsar 120 having a plurality of protrusions 121 provided at predetermined intervals on the outer periphery thereof is fitted on the drive shaft 70, while the cam ring 110 rotates together with the drive shaft 70. Protrusion 1 of pulsar 120
A rotation angle sensor 122 for converting the proximity / separation of 21 into a pulse signal is fixed.

The drive shaft 70 and the rotor 90 are connected to each other, and the rotation of the drive shaft 70 is transmitted to the rotor 90. Therefore, the rotor 90 rotates integrally with the drive shaft 70.

In the fuel injection pump 10 having the above structure, the rotation angle of the drive shaft 70 with respect to the cam ring 110, that is, the rotation angle of the rotor 90 with respect to the cam ring 110 is detected by counting the number of pulses emitted by the rotation angle sensor 122. Is possible.

The feed pump 80 is a vane type 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 from the suction port 84 provided in communication with the fuel inlet 15 is pressurized by the vanes 82 as the rotor 83 rotates and is discharged from the fuel discharge port 85 provided at a predetermined position. .

The rotor 90, which is connected to the drive shaft 70, is rotatably fitted in the cylinder hole 100a of the cylinder 100. Therefore, the cylinder hole 100a also functions as a bearing that rotatably supports the rotor 90.

Here, the rotor 90 has a pump chamber 91 in its large diameter portion, and a first fuel passage 94 for communicating a fuel inlet 92 and a fuel outlet 93 in its small diameter portion, and a fuel inlet 92. And a second fuel passage 95 communicating with the pump chamber 91.

Plural plungers (four in this embodiment) 96a to 96d capable of sliding in the radial direction of the rotor 90 are inserted in the pump chamber 91. Further, the fuel discharge port 93 is communicated with an annular groove 97 provided around the outer circumference of the rotor 90 at a position offset in the axial direction.

On the other hand, the cylinder 100 is provided with a fuel supply port 101 for communicating the fuel suction port 17 of the feed pump 80 and a fuel suction gallery 17 which is communicated with an external pipe (not shown) with the inner circumference of the cylinder 100. A plurality of fuel outflow ports 102, one end of which communicates with the constant pressure valve 60 on the outer circumference thereof and the other end of which opens to the inner circumference of the cylinder 100, are provided.

Here, each fuel intake port 101 is a port provided corresponding to each cylinder of the internal combustion engine, and when the rotor 90 rotates in synchronization with the rotation angle of the internal combustion engine, Fuel intake gallery corresponding to the rotation angle 1
7 is communicated with the fuel intake port 92 of the rotor 90, and the fuel discharge port 93 is communicated with the constant pressure valve 60 arranged in the specific cylinder.

The cylinder 100 is provided with a leak passage 103 for communicating the annular groove 97 provided in the rotor 90 and the spill valve 30. Here, the annular groove 97 is
As described above, the groove is provided over the entire circumference of the rotor 90. Therefore, the annular groove 97 and the spill valve 30 are always in communication with each other regardless of the rotation angle of the rotor 90.

The configuration around the pump chamber 91 will be described below with reference to FIG. 2 corresponding to the II-II section in FIG.
That is, the fuel injection pump 10 according to the present embodiment includes the rotor 9
This is a pump that boosts the pressure of fuel by driving four plungers 96a to 96d inserted in 0 with cams provided on the cam ring 110.

Here, the fuel pump 10 of this embodiment has six
Since it corresponds to a cylinder type internal combustion engine, the cam ring 110 has six cams 11 at equal intervals as shown in FIG.
0a to 110f are provided, and the four plungers 96a to 96d are all the plungers 96a to 96d.
Its position is designed so that there is a simultaneous lift on d. That is, the plungers 96a to 96d are attached to the cam 11
0a to 110f, a compression stroke of sliding toward the central axis of the rotor 90 is performed when passing through the cams 110a to 110f.
After passing f, a suction stroke of sliding toward the outside of the rotor 90 is performed.

Further, at the cam side end portions of the plungers 96a to 96d which come into contact with the roller shoes 98a to 98d, the cam lift provided by the cams 110a to 110f of the cam ring 110 can be smoothly carried out by the plungers 96a to 96d.
Roller shoe (roller holding member) 98a for transmission to
To 98d, and rollers 99a to 99d held by the roller shoes 98a to 98d. These plungers 96a to 96d and roller shoes 98a to 98
The d, the rollers 99a to 99d, and the cam surfaces of the cams 110a to 110f are lubricated with fuel (light oil).
Note that the roller shoes 98a to 98d are
It is formed in a substantially rectangular parallelepiped.

Inside the cam ring 110, the rotor 90
When the rotor 90 rotates, the plungers 96a to 96d make six reciprocating motions. When the reciprocating motion pressurizes the fuel in the pump chamber 91, the rotor 90 makes one revolution. During this period, that is, while the internal combustion engine makes two revolutions, the fuel pressure is increased six times for each equal rotation angle.

At this time, the fuel supply port 101 shown in FIG.
The fuel intake port 92 and the fuel intake port 92 communicate with each other under the condition that no cam lift is applied to the plungers 96a to 96d. Further, the fuel outflow port 102 and the fuel discharge port 9
3 is configured to communicate with the plungers 96a to 96d immediately before the lift occurs.

Therefore, when one of the fuel supply ports 101 and the fuel intake port 92 communicate with each other as the rotor 90 rotates, centrifugal force and fuel pressure supplied from the feed pump 80 are applied to the plungers 96a to 96d. As a result, the fuel is sucked into the pump chamber 91.

Then, when the communication between the fuel supply port 101 and the fuel suction port 92 is cut off, and then the lift occurs in the plungers 96a to 96d with the fuel outflow port 102 and the fuel discharge port 93 communicating with each other, the spill valve 3 is released.
Assuming that 0 is closed, high-pressure fuel is supplied to the constant pressure valve 60.

By the way, when the pressure of the fuel is increased by the plungers 96a to 96d, the spill valve 30 described above is used.
When the valve is open, the fuel pressure-fed from the pump chamber 91 flows back to the fuel tank or the like via the spill valve 30, and high-pressure fuel is not supplied to each cylinder.

That is, assuming that the spill valve 30 does not exist, the fuel injection timing for each cylinder is uniquely determined by the cam profile provided on the cam ring 110, and the degree of freedom regarding fuel injection timing control is significantly lost. It will be in a state of being

On the other hand, in the structure having the spill valve 30 as in the present embodiment, even if the pressure increase in the pump chamber 91 is started, the fuel injection is not performed as long as the spill valve 30 is opened as described above. In this sense, the fuel injection start timing is controlled by controlling the timing of switching the spill valve 30 from the open state to the closed state, and the fuel injection end timing is controlled by controlling the timing of opening the spill valve 30 again. It is possible to control with high precision.

In this embodiment, the rotor 90 has an annular groove 97.
And the fuel leak passage 103 is provided in the cylinder 100,
Further, the spill valve 30 for controlling the conduction of the fuel leakage passage 103 is provided in order to realize the fuel injection timing control as described above.

In this case, in order to control the fuel injection end timing with high accuracy, it is more advantageous that the leakage capability when the spill valve 30 is opened is higher.

By the way, when high pressure fuel is leaked using the spill valve 30, the first and second passages 9 provided in the rotor 90 are caused by the inertial effect of the fuel at the time of leak.
The internal pressure of 4, 95 may become negative. When the internal pressure in these passages becomes negative, the plungers 96a-9a
The relationship of the amount of fuel pumped with respect to the stroke of 6d changes, and the control accuracy of the fuel injection amount deteriorates.

In the present embodiment, a part of the fuel leaked through the spill valve 30 is returned to the fuel intake gallery 17, and the accumulator 50 is provided in communication with the fuel intake gallery 17 to prevent such an adverse effect. This is for effective removal.

That is, the fuel injection pump 10 of this embodiment.
In the above, since the configuration as described above is adopted,
Even if excessive fuel leaks due to the inertial effect at the time of fuel leak, a part of it acts to increase the internal pressure of the fuel intake gallery 17, and the pulsation of the internal pressure due to the recirculation of the leaked fuel causes accumulator 50. Since it is appropriately absorbed by, it is possible to stably inject a sufficient amount of fuel at the time of the next fuel intake.

Further, the fuel injection pump 10 of this embodiment is
A timer device 130 for changing the fixed angle of the cam ring 110 with respect to the housing 11 is provided. That is, the cam ring 110 is rotatably assembled to the howling 11, and is further fixed to a rod 133 sandwiched between timer pistons 131 and 132, as shown in FIG.

Here, the timer pistons 131 and 132
2 is a piston slidably inserted into the timer device 130. In FIG. 2, 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. On the left side of 132, the low pressure chamber 1 communicating with the fuel intake port 84 of the feed pump 80.
35 are formed respectively.

A spring 136 for urging the timer piston 132 to the right in FIG. 2 is arranged in the low pressure chamber 135, and the high pressure chamber 134 and the low pressure chamber 135 are electrically connected by the solenoid valve 140 shown in FIG. Are connected by external pipes that are controlled. In this case, the high pressure chamber 134 and the low pressure chamber 135
The cam ring 110 rotates in accordance with the pressure difference between and, and in this embodiment, the opening / closing valve of the solenoid valve 140 is duty-controlled to control the rotation angle to a desired value.

With this structure, the plunger 9 with respect to the rotation angle of the rotor 90, that is, the rotation angle of the internal combustion engine.
It is possible to change the lift characteristics of 6a to 96d, so that it is possible to further increase the degree of freedom regarding fuel injection timing control, and a fuel injection pump with excellent controllability is realized.

Next, the structure of the main part of the present invention will be described with reference to FIGS.

In this embodiment, as described above, the rotor 9
The four plungers 96a to 96d inserted in 0, the roller shoes 98 to 98d, and the rollers 99 to 99d are provided inside the cam ring 110. Since these four plunger drive mechanisms have the same configuration, the description of the symbols "a to d" will be omitted below.

As shown in the enlarged view of FIGS. 3 and 4, the roller 99 comprises a cylindrical roller half 99A and a roller half 99.
A small-diameter rod 99C is connected to B and a groove 99D is provided between the roller half body 99A and the roller half body 99B. The groove 99D is provided on the entire circumference of the roller shoe 98 so as not to come into contact with the cam surface 110A of the cams 110a to 110f.

The cams 110a to 110 are provided in the groove 99D.
A part of the fuel adhered to the cam surface 110A of f and the surface of the roller 99 is collected, and also functions as an oil sump. Therefore, since excess fuel is accumulated in the groove 99D, when lubrication is insufficient on the outer periphery of the roller halves 99A and 99B, the fuel in the groove 99D is supplied to the outer periphery of the roller halves 99A and 99B as lubricating oil. To be done.

In FIG. 3, a roller shoe 98 for rotatably holding the roller 99 is slidably inserted into a first guide hole 104 bored in the radial direction of the rotor 90, and a plunger 96 and a guide hole 104 are provided. It is slidably inserted into a second guide hole 105 that is coaxially formed in the radial direction.

The roller 99 is the cam 11 of the cam ring 110.
The first guide hole 10 is provided so that the roller shoe 98 can slide smoothly when passing through 0a to 110f.
The lateral width dimension of 4 is slightly larger than the lateral width dimension of the roller shoe 98. Therefore, the first guide hole 104
Between the width of the roller shoe 98 and the width of the roller shoe 98,
A slight clearance Sa is formed.

In order to allow the plunger 96 pressed by the roller shoe 98 to slide smoothly when the roller shoe 98 slides, the inner diameter of the second guide hole 105 is the outer diameter of the plunger 96. It is slightly larger. Therefore, a slight clearance Sb is formed between the inner diameter of the second guide hole 105 and the outer diameter of the plunger 96.

Further, both ends in the longitudinal direction of the roller 99 have partition walls 106 provided so as to sandwich the roller shoe 98,
It is close to 107 and faces through the clearance Sc.

The roller 99 having the above-described shape is formed by the cams 110a to 110a.
When the cam surface 110A of 110f rolls, the cam surface 110
It is in rolling contact with A and becomes a planetary roller with respect to the cam ring 110 and revolves while rotating on its axis.

Further, when the roller 99 normally rolls on the cam surface 110A, the roller 99 and the cam surface are basically in line contact, and the pressure distribution at the contact portion acts uniformly in the longitudinal direction. Will be done. And roller 9
The pressure distribution in the rolling direction of 9 is a typical elastohydrodynamic pressure distribution.

Assuming that an extra force in the traveling direction acts on the roller 99 in a direction other than the axial direction of the roller 99 (for example, the roller end), the end of the roller 99 on which the extra force acts is more than the other end. Move big. That is, a moment is generated with the point where the above-mentioned extra force is applied with the axis of the roller 99 as the line of action, and the point of force is the force point, and this moment causes the skew movement of the roller 99.

When the roller 99 skews, if the center of rotation of the roller shoe 98 holding the roller 99 does not coincide with the axis of the plunger 96, the roller shoe 98 holding the roller 99 moves in the same direction. Plunger 9 that rotates to and contacts roller shoe 98
The end portion of 6 receives the turning force of the roller shoe 98, and the plunger 96 tilts with respect to the axis. Therefore, when the turning force of the roller shoe 98 acts only on the end portion of the plunger 96 with which the roller shoe 98 abuts, the plunger 96 tilts in the guide hole 105 of the rotor 90. Further, when the pressing force in the axial direction (the force in the discharge direction) is applied by the cam surface 110A while the plunger 96 is in the inclined state, a moment with the axis line as the action line acts on the plunger 96, and the edge portion of the plunger 96 is moved. Occasionally, seizure or pitching (local holes) may occur in contact with the inner wall of the guide hole 105.

By the way, a surface pressure is generated on the oil film formed at the contact portion between the roller 99 and the cam surface 110A. Since the roller 99 rolls on the cam surface 110A, a frictional force corresponding to the magnitude of the surface pressure is generated.
The surface pressure of the contact portion between the cam surface 110A and the cam surface 110A becomes a resistance against the movement of the roller 99.

However, in the present embodiment, the roller 99 has the groove 99D between the roller half body 99A and the roller half body 99B.
As shown in FIG. 5, the surface pressures Fa and Fb from the oil film act only on the outer circumferences of the roller halves 99A and 99B rolling on the cam surface.

Then, in the case of the conventional roller in which the groove 99D is not provided on the outer periphery of the central portion, the surface pressure Fc from the oil film is smaller than that in the case where the groove 99D is provided as shown by the broken line in FIG. 5B ( Fa = Fb> Fc).

Therefore, the resistance force from the oil film concentrates on the end side as compared with the conventional case, and the resistance moment against the moment due to the extra force becomes larger than the conventional case.

Considering the force relationship of the roller 99 performing the skew movement, (excessive force moment)-(resistive force moment) becomes the skew moment. Therefore, when the resistance moment increases, the skew moment is suppressed so as to decrease. Therefore, when a large resistance force acts on the end portion of the roller 99 as described above, the horizontal state (inclination angle α
= 0), the resisting force moment that suppresses the inclination (angle of inclination α = 0) from increasing is increased.
9 stabilizes.

Therefore, the roller 99 is corrected to the horizontal state by the action of the resistance moment, so that the roller 9
The skew motion of 9 is suppressed, and the plunger 96 is prevented from being strongly rubbed against the inner wall of the guide hole 105 due to the inclination of the roller 99.

In the above embodiment, the groove 99D is provided on the outer periphery of the central portion of the roller 99. However, the present invention is not limited to this. For example, as shown in FIG. 7, the groove 110B is provided at the axial central portion of the cam surface 110A.
The same effect as that of the above-described embodiment can be obtained by providing the structure.

Further, as shown in FIG. 8, when the groove 99D is provided on the outer periphery of the central portion of the roller 99, and the groove 110B is provided on the axial central portion of the cam surface 110A, the same effect as that of the above embodiment can be obtained. can get.

Although the groove 99D has a quadrangular cross section in the above embodiment, it is not limited to this and may have a semicircular shape or a trapezoidal shape.

Further, the width dimension and the depth dimension of the groove 99D are set to appropriate dimensions according to the pump capacity, the rotation speed of the rotor 90, and the like.

[0081]

As described above, according to the present invention, since a groove extending in the circumferential direction is formed on at least one of the outer periphery of the central portion of the roller and the cam surface, the roller is not grooved as compared with a conventional roller. The surface pressure generated on the oil film on the cam surface becomes large, and the resistance force acting on the end portion of the roller increases. As a result, even if the roller skews, the resistance moment for returning the tilted roller increases, and one end of the roller is prevented from shifting in the traveling direction. Therefore, it is possible to suppress the skew movement of the roller, and it is possible to prevent the plunger from being rubbed against the inner wall of the guide hole while being inclined with respect to the axis due to the skew movement of the roller to cause seizure or pitting.

[Brief description of drawings]

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

FIG. 2 is a side sectional view showing a configuration around a pump chamber of a fuel injection pump.

FIG. 3 is an enlarged vertical sectional view of a main part of the present invention.

FIG. 4 is a vertical sectional view taken along the line IV-IV in FIG.

FIG. 5 is a diagram showing a pressure distribution when a roller rolls on a cam surface in a normal state.

FIG. 6 is a diagram showing a pressure distribution when a cam surface rolls with a roller inclined.

FIG. 7 is a vertical sectional view showing a modified example of the present invention.

FIG. 8 is a vertical sectional view showing another modification of the present invention.

[Explanation of symbols]

 10 fuel injection pump 20 overflow valve 30 spill valve 40 fuel recirculation valve 50 accumulator 60 constant pressure valve 70 drive shaft 80 feed pump 90 rotor 91 pump chamber 96 (96a to 96d) plunger 98 (98a to 98d) roller shoe 99 (99a to 99d) ) Roller 99A, 99B Roller half body 99C Small diameter rod 99D Groove 100 Cylinder 101 Fuel supply port 102 Fuel outflow port 104 First guide hole 105 Second guide hole

Claims (1)

[Claims] 1. A cam ring having a cam on its inner peripheral surface, a rotor rotatably driven by a drive shaft, a plunger inserted into a guide hole bored in the radial direction of the rotor, and an end portion of the plunger. A rotor holding member provided in contact with the plunger and slidable in the radial direction of the rotor; and a roller rotatably held by the roller holding member and rolling on the cam surface of the cam ring. In a fuel injection pump that pressurizes fuel by a discharge operation of a plunger and supplies it to an engine as the engine is driven to rotate, a groove extending in the circumferential direction is formed on at least one of the outer periphery of the central portion of the roller or the cam surface. A fuel injection pump characterized by being formed.