JP2003232270A - Fuel injection pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection pump for reducing its seizure by accelerating the formation of an oil film on a sliding part. <P>SOLUTION: A cam ring 24 abuts on a plunger 21 and a plunger 22 with a driving shaft 15 held therebetween. An end face 21a of the plunger 21 and an end face 22a of the plunger 22 slide along a first sliding face 24a of the cam ring 24 and along a second sliding face 24b of the cam ring 24, respectively. The first sliding face 24a and the second sliding face 24b are formed in non- parallel to each other. When the end face 21a of the plunger 21 slides along the first sliding face 24a, a predetermined angle α is therefore formed between the end face 22a of the plunger 22 and the second sliding face 24b and a gap is formed between the plunger 22 and the cam ring 24. Thus, a fuel for lubrication flows between the end face 22a and the second sliding face 24b, and when the plunger 22 is in a pressure stroke, the oil film is formed between the sliding end face 22a and the second sliding face 24b to reduce the seizure. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an internal combustion engine (hereinafter,
An internal combustion engine is called an "engine." ) Fuel injection pump.

[0002]

2. Description of the Related Art For example, as a fuel injection pump for a diesel engine, a fuel injection pump provided with a cam for driving a plunger as a movable member is used. In the fuel injection pump as described above, the plunger reciprocates in the axial direction inside the cylinder, so that the fuel is sucked into the pressurizing chamber and is pressurized. A cam ring is provided between the plunger and the cam, and the rotational movement of the drive shaft driven by the engine is converted into the reciprocating movement of the plunger by the cam and the cam ring. As a result, the plunger is reciprocally driven inside the cylinder. In recent years, in order to improve engine output and fuel efficiency and reduce emissions of NOx, black smoke, etc. from the engine, further increase in fuel injection pressure is required.

[0003]

In order to increase the fuel injection pressure, it is necessary to increase the pressure of the fuel injected by the fuel injection pump and increase the pressure of the fuel discharged from the fuel injection pump. When the pressure of the fuel is increased, the load of the fuel injection pump becomes excessive, and a large force acts particularly on the sliding portion such as between the sliding cam ring and the plunger. Therefore, seizure may occur between the members forming the sliding portion. Therefore, a part of the fuel is supplied to the sliding part such as between the cam ring and the plunger, and the sliding part is lubricated by an oil film formed by the supplied fuel.

However, during the pressurizing stroke in which the plunger pressurizes the fuel in the pressurizing chamber, a large force is applied to the plunger in the cam ring direction due to the pressure of the fuel in the pressurizing chamber, and the plunger and the cam ring come into close contact with each other. On the other hand, during the intake stroke of sucking fuel into the pressurizing chamber, the plunger is pressed against the cam ring by the biasing member such as a spring, so that the plunger and the cam ring are in close contact with each other as in the pressurizing stroke. Therefore, the plunger and the cam ring are always in close contact with each other. As a result, fuel for lubrication does not easily flow into the sliding portion between the plunger and the cam ring, which makes it difficult to form an oil film and may cause seizure.

Therefore, an object of the present invention is to provide a fuel injection pump that promotes the formation of an oil film in the sliding portion and reduces seizure.

[0006]

According to the fuel injection pump of the first or second aspect of the present invention, the sliding surface of the cam ring slides when the fuel is sucked into the pressurizing chamber. Form a gap between and. When injecting fuel into the pressurizing chamber, it is not necessary to apply a large force to the movable member,
There is no problem even if a gap is formed between the movable member and the cam ring. By forming a gap between the end surface of the movable member and the sliding surface of the cam ring, the fuel flows between the end surface of the movable member and the sliding surface of the cam ring when the fuel with a small force applied to the movable member is sucked. To do. Therefore, when a large force is applied to the movable member, formation of an oil film is promoted between the end surface of the sliding movable member and the sliding surface of the cam ring, and seizure can be reduced.

According to the fuel injection pump of the third aspect of the present invention, when the two movable members are arranged with the drive shaft interposed therebetween, one of the movable members pressurizes the fuel in the pressurizing chamber. At this time, the other movable member is in the suction stroke for sucking fuel into the pressurizing chamber. Therefore, the movable member and the cam ring slide during the pressurization process in which a large force is applied to the movable member by the fuel in the pressure chamber. On the other hand, when the force applied to the movable member is small during the suction stroke, a gap is formed between the movable member and the cam ring. Therefore, an oil film of fuel can be formed between the end surface of the movable member and the sliding surface of the cam ring, and seizure can be reduced.

According to the fuel injection pump of the fourth aspect of the present invention, the cam ring is formed such that the sliding surface that abuts on one movable member and the sliding surface that abuts on the other movable member are non-parallel. When one of the movable members is in the pressurizing stroke, the end surface of the movable member and the sliding surface of the cam ring are in surface contact with each other by a large force applied to the movable member by the fuel in the pressurizing chamber and slide. By forming the two sliding surfaces of the cam ring non-parallel to each other, when the end surface of one movable member and the sliding surface of the cam ring are sliding, the end surface of the other movable member and the sliding surface of the cam ring are A gap is formed between them. Therefore,
When the movable member is in the intake stroke, an oil film of fuel can be formed between the end surface of the movable member and the sliding surface of the cam ring, and seizure can be reduced.

According to the fuel injection pump of the fifth aspect of the present invention, the cam ring is provided with the convex portion projecting toward the movable member. The convex portion comes into contact with the movable member during the suction stroke in which fuel is sucked into the pressurizing chamber. Therefore, during the suction stroke, the movable member rides on the convex portion, so that a gap is formed between the end surface of the movable member and the sliding surface of the cam ring. Therefore, when the movable member is in the suction stroke, an oil film of fuel can be formed between the end surface of the movable member and the sliding surface of the cam ring, and seizure can be reduced. According to the fuel injection pump of claim 6 of the present invention,
When fuel is sucked into the pressurizing chamber, the end surface and the sliding surface are in contact with each other on one end side in the radial direction of the end surface and form a gap on the other end side. Therefore, when the movable member is in the intake stroke, an oil film due to fuel can be formed between the end surface of the movable member and the sliding surface of the cam ring, and seizure can be reduced.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment showing an embodiment of the present invention will be described below with reference to the drawings. A fuel injection pump according to an embodiment of the present invention is shown in FIG. The fuel injection pump is applied to a common rail fuel injection system of a diesel engine.

As shown in FIG. 2, the housing 10 of the fuel injection pump 1 has a housing body 11 and cylinder heads 12 and 13. The housing body 11 is made of aluminum. The cylinder heads 12 and 13 are made of iron, and the cylinders 12a and 13a formed therein respectively support a plunger 21 and a plunger 22 as movable members so as to be capable of reciprocating in the axial direction. The inner peripheral surfaces of the cylinder heads 12a and 13a, the end surface of the check valve 14 and the end surfaces of the plungers 21 and 22 form pressurizing chambers 31 and 32. In this embodiment, the cylinder head 12 and the cylinder head 13 are formed in substantially the same shape, but the forming positions of screw holes, fuel passages, etc. are different. On the other hand, the formation positions of the screw holes and the fuel passages are made the same, and the cylinder head 12 and the cylinder head 13 are
It is also possible to make the shapes of the same.

The drive shaft 15 is rotatably supported by the housing 10 via a journal 16. Housing 1
An oil seal 17 seals between 0 and the drive shaft 15. As shown in FIG. 1, a cam 2 having a circular cross section
3 is eccentrically formed with respect to the drive shaft 15 and is integrally formed.
In the case of the two-cylinder fuel injection pump 1 as in the present embodiment, two plungers 21 and 22 are arranged opposite to each other by 180 ° with the drive shaft 15 interposed therebetween. The center axes of the plunger 21 and the plunger 22 are arranged in parallel.

The cam ring 24 has a quadrilateral outer shape, and a cam ring 24 and a bush 25 slidable on the cam 23 are interposed between the cam ring 24 and the cam 23. The cam ring 24 is the end surface 2 of the plunger 21.
1a and a first sliding surface 24a slidable with the plunger 22
End surface 22a and a second sliding surface 24b that is slidable. The first sliding surface 24a and the second sliding surface 24b are formed non-parallel to each other.

The spring 26 biases the plungers 21 and 22 toward the cam ring 24. Cam ring 24
Rotates with the rotation of the cam 23 and revolves without sliding while rotating with the cam 23. As a result, the sliding cam ring 24 and the plungers 21 and 22 slide while reciprocating in the left-right direction in FIG. At this time, the plunger 21 and the plunger 22 are moved in the axial direction by the cam 23 and the cam ring 24 as the drive shaft 15 rotates.
It is driven with the phase shifted by 0 °. That is, when the plunger 21 rises in the cylinder 12a toward the check valve 14 and pressurizes the fuel in the pressurizing chamber 31, the plunger 22 descends in the cylinder 13a toward the drive shaft 15 and sucks fuel into the pressurizing chamber 32. To do.

The plunger 21, the plunger 22, the drive shaft 15, the cam 23 and the cam ring 24 are composed of a housing body 11, a cylinder head 12 and a cylinder head 13.
It is housed in a housing chamber 18 formed by. Containment room 1
8 is filled with light oil as fuel. The plunger 21 and the plunger 22 are reciprocally driven by the cam 23 via the cam ring 24 as the drive shaft 15 rotates, and pass from the fuel inflow passage 33 through the check valve 14 to the pressurizing chamber 3.
The fuel sucked into Nos. 1 and 32 is pressurized. The check valve 14 prevents the fuel from flowing back from the pressurizing chambers 31, 32 to the fuel inflow passage 33.

The fuel discharge passage 34 is provided in the cylinder head 12
Further, the cylinder head 13 is linearly formed, and communicates with the pressurizing chambers 31, 32. On the downstream side of the fuel discharge passage 34 formed in the cylinder head 12, a long-hole fuel chamber 3 having a larger passage area than the fuel discharge passage 34 is provided.
5 is formed, and the check valve 36 is housed in the fuel chamber 35. An accommodation hole 37 having a larger passage area than the fuel chamber 35 is formed on the fuel downstream side of the fuel chamber 35. The accommodation hole 37 opens in the outer peripheral wall of the cylinder head 12 to form a fuel outlet. The connecting member 40 for connecting the fuel pipe is housed in the housing hole 37 by screwing or the like. Connection member 4
The fuel passage 41 is formed inside the
1 communicates with the fuel chamber 35. The fuel passage 41 is formed substantially on the same straight line as the fuel discharge passage 34.

The check valve 36 disposed on the fuel downstream side of the fuel discharge passage 34 of the cylinder head 12 is a check valve 36.
The fuel is prevented from flowing backward from the fuel chamber 35 on the downstream side of the fuel to the pressurizing chamber 31 via the fuel discharge passage 34.
The connecting member 40 is connected to a common rail (not shown) by a fuel pipe (not shown), and the fuel pressurized by the fuel injection pump 1 goes to the common rail via the fuel passage 41 and the fuel pipe formed in the connecting member 40. Supplied. On the common rail, the fuel discharged from the fuel injection pump 1 is stored in a pressure-accumulated state. An injector (not shown) installed in each cylinder of the engine (not shown) is connected to the common rail, and the high-pressure fuel stored in the common rail is supplied to the injector. The injector injects fuel supplied from the common rail into each cylinder of the engine at a predetermined time and for a predetermined period.

The cylinder head 13 is a housing body 11
2 is disposed below. Similarly to the cylinder head 12, the cylinder head 13 has a fuel discharge passage 34.
A storage hole 37 and the like are formed therein, and the check valve 36, the connection member 40, and the like are stored therein.

At the end of the drive shaft 15, pressure chambers 31, 32 are provided.
A feed pump 50 for supplying fuel to is installed. The feed pump 50 causes the inner rotor 51 and the outer rotor 52 to rotate relative to each other as the drive shaft 15 rotates, so that the fuel in a fuel tank (not shown) is pressurized in the pressurizing chamber 31,
Delivery to 32. A metering valve (not shown) is installed in the middle of the fuel inflow passage 33 that connects the feed pump 50 and the pressurizing chambers 31, 32. The metering valve regulates the flow rate of fuel fed from the feed pump 50 to the pressurizing chambers 31, 32.

Next, the operation of the fuel injection pump 1 according to this embodiment will be briefly described. The cam 23 rotates with the rotation of the drive shaft 15, and the cam ring 24 revolves without rotating with the rotation of the cam 23. As the cam ring 24 revolves, the sliding surface of the cam ring 24 and the end surfaces of the plungers 21, 22 slide, and the plungers 21, 22 are reciprocally driven.

When the plungers 21 and 22 at the top dead center are lowered toward the drive shaft 15 as the cam ring 24 revolves, the fuel which is discharged from the feed pump 50 and whose flow rate is adjusted by the control of a metering valve (not shown). Fuel inflow passage 33
Through the check valve 14 into the pressurizing chambers 31, 32. When the plungers 21 and 22 reaching the bottom dead center rise toward the top dead center again, the check valve 14 is closed and the pressurizing chamber 3
The fuel pressures of 1 and 32 increase. When the fuel pressure in the pressurizing chambers 31, 32 becomes higher than the fuel pressure in the fuel passage 41, the check valve 36 opens and the fuel pressurized in the pressurizing chambers 31, 32 is discharged to the fuel passage 41. It

The fuel discharged from the pressurizing chambers 31, 32 is
It is delivered to the fuel passage 41 through the fuel discharge passage 34, the check valve 36, and the fuel chamber 35. The fuel passage 41 communicates with a common rail (not shown), and the fuel delivered to the fuel passage 41 is supplied to the common rail. The common rail accumulates the fuel having a pressure fluctuation supplied from the fuel injection pump and holds it at a constant pressure. Since the plunger 21 and the plunger 22 are driven with a phase difference of 180 °, fuel is alternately discharged from the pressurizing chamber 31 and the pressurizing chamber 32.

Next, the relationship between the plungers 21 and 22 and the cam ring 24 of the fuel injection pump 1 according to this embodiment will be described in detail. The intake stroke is when the plungers 21 and 22 descend toward the drive shaft 15 and suck the fuel into the pressurizing chambers 31 and 32.
The pressurization stroke is a time when the fuel that has risen in four directions and is sucked into the pressurizing chambers 31, 32 is pressurized. Since the plunger 21 and the plunger 22 are arranged so as to face each other with the cam ring 24 sandwiched therebetween, they are driven in a state of being 180 ° out of phase with each other.
That is, when the plunger 21 is in the pressure stroke, the plunger 22 is in the suction stroke.

As shown in FIG. 3, when the plunger 21 is at the bottom dead center, the plunger 22 is at the top dead center. At this time, the rotation angle θ of the drive shaft 15 is set to 0 °. Drive shaft 15
When the cam 23 and the cam ring 24 rotate with the rotation of, the plunger 21 that abuts on the first sliding surface 24a side of the cam ring 24 starts moving from the bottom dead center to the top dead center. The rotation angle θ of the drive shaft 15 of the plunger 21 is 0 °.
When it is in the range of <θ <180 °, the pressurization process is performed and the cylinder 12a rises from the bottom dead center to the top dead center. Similarly, in the plunger 22, the rotation angle θ of the drive shaft 15 is 0 °.
When it is in the range of <θ <180 °, the suction stroke occurs and the inside of the cylinder 13a descends from the top dead center to the bottom dead center.

When the plunger 21 is in the pressure stroke, a large force is applied to the plunger 21 in the direction of the cam ring 24 by the high pressure fuel in the pressure chamber 31. On the other hand, the urging force of the spring 26 shown in FIG. 1 is applied to the plunger 22 in the direction of the cam ring 24. The force applied to the plunger 21 by the pressure of the fuel in the pressurizing chamber 31 is larger than the biasing force of the spring 26 applied to the plunger 22.

Further, as shown in FIG. 1, the first sliding surface 24a and the second sliding surface 24b of the cam ring 24 are formed non-parallel to each other, and the plungers 21 and 22 are formed such that their central axes are parallel to each other. There is. Therefore, when the force applied to the plunger 21 and the force applied to the plunger 22 are large or small, the end surface 21a of the plunger 21 to which a larger force is applied is applied.
And the first sliding surface 24a of the cam ring 24 are in surface contact with each other.
Therefore, the rotation angle θ of the drive shaft 15 is 0 ° <θ <18.
When in the range of 0 °, the end surface 21a of the plunger 21 and the first sliding surface 24a of the cam ring 24 slide.

On the other hand, as described above, the first sliding surface 24a and the second sliding surface 24b of the cam ring 24 are formed non-parallel to each other, and the plungers 21 and 22 are formed such that their central axes are parallel to each other. . Therefore, the end face 2 of the plunger 21
When 1a and the first sliding surface 24a of the cam ring 24 make surface contact and slide, a predetermined angle α is formed between the end surface 22a of the plunger 22 and the second sliding surface 24b of the cam ring 24. . As a result, a gap is formed between the end surface 22a of the plunger 22 and the second sliding surface 24b of the cam ring 24. Thereby, the end surface 22a and the second sliding surface 24b
And are in contact with each other on one end side in the radial direction of the end face 22a and form a gap on the other end side. Therefore, the fuel with which the storage chamber 18 is filled can flow into the gap formed between the end surface 22 a of the plunger 22 and the second sliding surface 24 b of the cam ring 24. Cam ring 24
The angle formed by the first sliding surface 24a and the second sliding surface 24b is such that the gap formed between the end surface 22a of the plunger 22 and the second sliding surface 24b of the cam ring 24 is the end surface 22a and the second sliding surface. It is set to be larger than the surface roughness of the moving surface 24b.

As shown in FIG. 3, when the rotation angle θ of the drive shaft 15 becomes θ = 180 °, the plunger 21 reaches the top dead center and the plunger 22 reaches the bottom dead center. Therefore, the plunger 21 finishes the pressurizing stroke, and the plunger 2
2 ends the inhalation stroke. The rotation angle θ of the drive shaft 15 is 1
When 80 ° <θ, contrary to the range of 0 ° <θ <180 °, the plunger 21 shifts to the suction stroke and the plunger 2
2 shifts to the pressure stroke. Therefore, the end surface 22a of the plunger 22 and the second sliding surface 24b of the cam ring 24 slide. On the other hand, between the end surface 21 a of the plunger 21 and the first sliding surface 24 a of the cam ring 24, the end surface 22 a of the plunger 22 and the end surface 24 of the cam ring 24 described above are provided.
A gap is formed as in b. Therefore, the fuel with which the storage chamber 18 is filled can flow into the gap formed between the end surface 21a of the plunger 21 and the first sliding surface 24a. Since the first sliding surface 24a and the second sliding surface 24b are non-parallel, the gap formed between the end surface 21a of the plunger 21 and the first sliding surface 24a of the cam ring 24 is the end surface of the plunger 22. The size is approximately the same as the gap formed between 22a and the second sliding surface 24b of the cam ring 24. When the rotation angle θ of the drive shaft 15 becomes θ = 360 °, the drive shaft 15 makes one rotation and θ = 0 ° in the initial state, and the above operation is repeated.

As described above, according to the fuel injection pump 1 of the first embodiment of the present invention, the plunger 21 and the plunger 22 are provided with the cam ring 2 during the intake stroke.
A gap is formed between the two. Therefore, plunger 2
1 or the plunger 22 during the suction stroke, the storage chamber 18
The fuel filled in the end face 21a of the plunger 21 is
And the first sliding surface 24a or between the end surface 22a of the plunger 22 and the second sliding surface 24b of the cam ring 24. Between the end surface 21a of the plunger 21 and the first sliding surface 24a, or the end surface 2 of the plunger 22.
2a and the second sliding surface 24b, when the fuel flows between the plunger 21 and the plunger 22, the end surface of the plunger 21 is moved during a pressurization stroke in which a large force is applied to the plunger 21 or the cam ring 24 toward the cam ring 24. The formation of an oil film between 21a and the first sliding surface 24a of the cam ring 24, or between the end surface 22a of the plunger 22 and the second sliding surface 24b of the cam ring 24 is promoted. Therefore, seizure between the plunger 21 or the plunger 22 and the cam ring 24 can be reduced. Further, in the first embodiment, the first sliding surface 24a and the second sliding surface 2 of the cam ring 24 are
It is only formed non-parallel with 4b. Therefore, the cam ring 24 has a simple structure and can be easily processed.

(Second Embodiment) FIG. 4 shows a fuel injection pump according to a second embodiment of the present invention. The same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.
As shown in FIG. 4, the cam ring 27 of the fuel injection pump according to the second embodiment has a convex portion 28. Convex portion 28
Are formed on the first sliding surface 27a side and the second sliding surface 27b side of the cam ring 27, respectively. In the second embodiment, the first sliding surface 27a and the second sliding surface 27b are formed substantially parallel to each other.

The convex portion 28 is formed so as to project from the first sliding surface 27a and the second sliding surface 27b of the cam ring 27 toward the plunger 21 or the plunger 22, respectively. The height of the convex portion 28 is a clearance formed between the end surface 21a of the plunger 21 and the first sliding surface 27a of the cam ring 27 and between the end surface 22a of the plunger 22 and the second sliding surface 27b of the cam ring 27. , End face 21a, end face 2
2a, the first sliding surface 27a and the second sliding surface 24b are set to be larger than the surface roughness. The plunger 21 or the plunger 22 and the cam ring 27 are shown in FIG.
Sliding while reciprocating in the left and right directions. Therefore, the position where the plungers 21 and 22 come into contact with the cam ring 27 differs between the pressurizing stroke and the suction stroke. Therefore, the convex portion 2
8 is formed at a position where the plungers 21 and 22 and the cam ring 27 come into contact with each other during the suction stroke.

The relationship between the plunger 21 and the plunger 22 and the cam ring 27 of the fuel injection pump according to the second embodiment will be described. As shown in FIG. 5, when the rotation angle θ of the drive shaft 15 is θ = 0 °, the plunger 21 is located at the bottom dead center and the plunger 22 is located at the top dead center.
When the rotation angle θ of the drive shaft 15 is 0 ° <θ <180 °,
The plunger 21 is in the pressurizing stroke and the plunger 22 is in the suction stroke. When the plunger 21 is in the pressure stroke, the end surface 21a of the plunger 21 comes into surface contact with the first sliding surface 27a of the cam ring 27 and slides. Meanwhile, the plunger 22
Moves to the portion where the convex portion 28 is formed as the cam ring 27 moves relative to the left-right direction in FIG.

As described in the first embodiment, the force exerted on the plunger 21 by the fuel pressure is larger than the biasing force of the spring 26 exerted on the plunger 22. Therefore, when the plunger 22 moves to the position of the convex portion 28 of the cam ring 27, the plunger 22 rides on the convex portion 28. Therefore, a gap is formed between the plunger 22 and the cam ring 27. As a result, the end surface 22a and the second sliding surface 27b are in contact with each other on one end side in the radial direction of the end surface 22a and form a gap on the other end side. Therefore, the fuel in the storage chamber 18 flows between the end surface 22 a of the plunger 22 and the second sliding surface 27 b of the cam ring 27.

When the rotation angle θ of the drive shaft 15 becomes 180 ° <θ, the plunger 21 shifts to the suction stroke and the plunger 22 shifts to the pressurization stroke. Therefore, contrary to when the rotation angle θ of the drive shaft 15 is in the range of 0 ° <θ <180 °, the plunger 21 rides on the convex portion 28 formed on the cam ring 27. As a result, a gap is formed between the plunger 21 and the cam ring 27, and the plunger 2
The fuel can flow between the end surface 21 a of the No. 1 and the first sliding surface 27 a of the cam ring 27.

In the second embodiment, similarly to the first embodiment, when the plunger 21 or the plunger 22 is in the suction stroke, the end face 21a of the plunger 21 and the first sliding face 27a of the cam ring 27 or the end face 22a of the plunger 22 and the cam ring. A gap is formed between the second sliding surface 27 b of 27 and the fuel in the storage chamber 18 flows in. Therefore, the plunger 21
Formation of an oil film between the end surface 21a of the cam ring 27 and the first sliding surface 27a of the cam ring 27, or between the end surface 22a of the plunger 22 and the second sliding surface 27b of the cam ring 27 is promoted. Therefore, the plunger 21 or the plunger 22
The seizure between the cam ring 27 and the cam ring 27 can be reduced.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the vicinity of a plunger and a cam ring taken along the line I-I of FIG.

FIG. 2 is a schematic sectional view showing a fuel injection pump according to a first embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a relationship between a plunger and a cam ring according to rotation of a drive shaft in the fuel injection pump according to the first embodiment of the present invention.

FIG. 4 is a schematic cross-sectional view showing the vicinity of a plunger and a cam ring of a fuel injection pump according to a second embodiment of the present invention.

FIG. 5 is an explanatory diagram showing a relationship between a plunger and a cam ring according to rotation of a drive shaft in a fuel injection pump according to a second embodiment of the present invention.

[Explanation of symbols]

1 Fuel injection pump 10 housing 11 Housing body (housing) 12, 13 Cylinder head (housing) 12a, 13a cylinder 15 drive shaft 21,22 Plunger 21a, 22a end faces 23 cam 24, 27 cam ring 24a, 27a First sliding surface 24b, 27b Second sliding surface 28 convex 31, 32 Pressurizing chamber

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 3G066 AA07 AB02 AD02 BA49 CA01S                       CA15Z                 3H070 AA02 BB03 BB25 CC27 DD35                 3H075 AA03 BB03 CC15 DB04 DB26

Claims (6)

[Claims] 1. A movable member, a housing that has a cylinder that supports the movable member so as to be capable of reciprocating in the axial direction, and forms a pressurizing chamber with the movable member, and a cam that is eccentrically formed integrally. A drive shaft and a sliding surface that is installed on the outer peripheral side of the cam, is capable of transmitting the drive force of the drive shaft to the movable member, and has a sliding surface that slides on the end surface of the movable member, And a cam ring that forms a gap between the end surface and the sliding surface when fuel is sucked into the pressurizing chamber by moving in the drive axis direction. 2. The fuel injection pump according to claim 1, wherein two movable members facing each other with the drive shaft interposed therebetween are provided. 3. When one of the two movable members pressurizes the fuel in the pressurizing chamber, the end surface of the one movable member slides on the sliding surface of the cam ring, The fuel injection pump according to claim 2, wherein a gap is formed between the end surface of the other movable member and the sliding surface of the cam ring. 4. The fuel according to claim 3, wherein the cam ring has a sliding surface abutting against one movable member and a sliding surface abutting against the other movable member are formed non-parallel to each other. Injection pump. 5. The cam ring has a convex portion formed so as to project in each direction of the movable member and abutting against each of the movable members when fuel is sucked into each of the pressurizing chambers. The fuel injection pump according to claim 3. 6. When fuel is sucked into the pressurizing chamber, the end surface and the sliding surface are in contact with each other on one end side in the radial direction of the end surface and have a gap on the other end side. The fuel injection pump according to claim 1, wherein the fuel injection pump is formed.