JPH1172061A - Fuel pressurizing pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent leakage of the fuel from a sliding gap between a plunger and cylinder, eliminate necessity for strict dimensional control of seal components, reduce the friction between the plunger and cylinder, and enhance the durability of component parts. SOLUTION: A ring-shaped groove 57 is formed at the peripheral surface of a plunger 8. A seal ring 59 made of resin exhibiting small elongation and contraction which is put in slide contact inside a cylinder hole 22 and a rubber O-ring 58, which exhibits greater elongation and contraction than the seal ring 59 and presses it 59 to the cylinder hole 22, are accommodated in the groove 57. Despite a certain disorder in the dimensional accuracy, the seal ring 59 is pressed by the O-ring 58 and put in tight contact with the cylinder hole 22 certainly.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plunger-type fuel pressurizing pump used for a fuel injection device of an automobile, and more particularly to an improvement capable of reliably preventing fuel from leaking from a sliding gap between a cylinder and a plunger. The present invention relates to an applied fuel pressurizing pump.

[0002]

2. Description of the Related Art A plunger type pump has conventionally been used as a fuel pressurizing pump for a fuel injection device of an automobile. In this fuel pressurizing pump, the plunger is pressed by a rotating cam that rotates integrally with the drive shaft, and moves forward and backward in the cylinder. The pump chamber formed between the cylinder and the plunger performs suction, pressurization, and discharge of fuel. It is supposed to do.

[0003] However, in this type of fuel pressurizing pump, a rotary cam is arranged close to a cylinder.
It is necessary to surely prevent the fuel leaked from the sliding gap between the plunger and the cylinder from flowing into a portion requiring lubrication such as a cam sliding portion. In order to cope with this, a diaphragm is disposed between the outer peripheral surface of the tip of the plunger projecting toward the cam chamber and the peripheral edge of the cylinder hole, and the fuel from the sliding gap to the cam chamber is provided. Has been devised in which the inflow of air is prevented by the diaphragm. This technique is disclosed, for example, in Japanese Utility Model Laid-Open No. 6-43274.

[0004]

However, in the case of the conventional fuel pressurizing pump described above, a diaphragm which requires a large unit price and a large occupied space is used, so that the manufacturing cost is increased and the pump itself is increased in size. There is a problem of inviting.

Further, as a plan for realizing low cost and miniaturization, at present, it is conceivable to dispose a seal ring made of rubber or a resin with small elasticity on the sliding surface on one side of the plunger and the cylinder. However, when such a seal ring is used, another problem as described below can be considered.

That is, when a rubber seal ring is used, the sealing property is ensured by bringing the seal ring into contact with the sliding surface with a certain contact pressure, but the contact area increases due to its elastic deformation. In this connection, the contact resistance is increased, the friction at the time of sliding between the plunger and the cylinder is increased, and the sealing performance is liable to be deteriorated with use over time.

Further, when a resin-made seal ring having small elasticity is used, the problem of friction and durability is solved, but since the seal ring has almost no elasticity, strict control of its dimensional accuracy is strictly required. This must be performed, and if the accuracy is slightly increased, malfunction of the plunger or leakage of fuel from the front side or the back side of the seal ring occurs.

Accordingly, an object of the present invention is to provide a fuel pressurizing pump capable of reliably preventing fuel from leaking from a sliding gap between a plunger and a cylinder without causing these problems.

[0009]

Means for Solving the Problems As means for solving the above-mentioned problems, according to the first aspect of the present invention, a plunger is slidably housed in a cylinder, and fuel is applied between the cylinder and the plunger. In a fuel pressurizing pump in which a pump chamber for pressurizing is formed and a rotary cam for moving the plunger forward and backward is arranged outside the cylinder, an annular groove is formed on a sliding surface on one of the plunger and the cylinder. A seal ring made of a resin having a small elasticity and closely contacting the sliding surface on the other side, and the seal ring made of resin pressing the seal ring in the direction of the sliding surface on the other side in the annular groove. An elastic ring having greater elasticity than the elastic ring is accommodated. Since the resin seal ring with small elasticity is pressed by the elastic ring and comes into close contact with the sliding surface on the other side, even if the seal ring has some dimensional accuracy, a seal ring with small sliding resistance can be used. Ensure close contact with the other sliding surface.

According to a second aspect of the present invention, in the first aspect of the invention, the elastic ring is formed of an O-ring made of rubber. In this case, the gap between the annular groove and the back side of the seal ring is sealed by the elastic ring.

According to a third aspect of the present invention, in the first aspect of the present invention, the elastic ring is constituted by a rubber O-ring and a metal urging ring, and the O-ring and the urging ring are formed by shafts of a plunger and a cylinder. It was arranged side by side along the direction. In the case of the present invention, the gap between the annular groove and the back surface side of the seal ring is sealed by a rubber O-ring, and the seal ring is urged by the rubber O-ring and the metal urging ring to form a sliding surface. In close contact. In addition, a sufficient pressing force of the seal ring by the O-ring may not be obtained due to a set of the rubber material of the O-ring or a decrease in flexibility due to high-temperature creep of the seal ring. The seal ring is securely brought into close contact with the sliding surface by the pressing force of the metallic urging ring.

According to a fourth aspect of the present invention, in the third aspect of the invention, the biasing ring is constituted by a C ring made of spring steel. In this case, the seal ring can be securely brought into close contact with the sliding surface while having a very simple structure.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the axial length of the seal ring is formed to be longer than the axial length of the elastic ring. In this case, the resin seal ring, which is smaller in elasticity than the elastic ring pressed by the elastic ring, is deformed into a mountain shape, and an oil film of lubricating oil is easily formed on the bulged outer peripheral surface.

According to a sixth aspect of the present invention, in any one of the first to fifth aspects of the present invention, the annular groove is formed in the first-step groove in which the seal ring is engaged and the bottom of the first-step groove. And a second-step groove in which the elastic ring is engaged. In this case, since the positions of the seal ring and the elastic ring are kept constant, the contact position of the seal ring with the other sliding surface is always constant, and the sealing performance and sliding performance are stabilized.

According to a seventh aspect of the present invention, in any one of the first to sixth aspects of the present invention, lubricating oil is supplied to the seal ring in the vicinity of the position where the seal ring is disposed on the sliding surface of the cylinder. The oil supply hole is formed. In this case, the lubricating oil is more stably supplied to the seal ring, and an oil film is easily formed on the seal ring.

According to an eighth aspect of the present invention, in any one of the first to seventh aspects of the present invention, the communication surface communicating with the low-pressure passage closer to the pump chamber than the position where the seal ring is disposed on the sliding surface of the cylinder. A passage was formed. In this case, the high-pressure fuel leaked from the pump chamber temporarily drops to the pressure in the low-pressure passage in the sliding gap between the plunger and the cylinder, so that the fuel pressure acting on the seal ring becomes low.

[0017]

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

In the drawings, reference numeral 1 denotes a fuel pressurizing pump according to the present invention. In this embodiment, the fuel pressurizing pump 1 is used in a fuel injection device of an automobile engine. That is, as shown in FIG. 2, a supply pump 3 driven by a motor M is connected to a suction passage 2 of a fuel pressurizing pump 1 via a low-pressure regulator 4, and an injector 6 of a fuel injection device is connected to a discharge passage 5. The fuel is supplied from the fuel tank 7 through the supply pump 3 and is supplied to the injector 6 after being pressurized to the set high pressure by the pump 1 according to the present invention.

The fuel pressurizing pump 1 has a single plunger 8 which moves forward and backward to perform a pump action, and the plunger 8
A drive shaft 9 that is arranged along a direction perpendicular to the forward and backward directions of the drive shaft and rotates by receiving the power of the engine, and a rotary cam that is provided integrally with the drive shaft 9 and transmits an operating force to the plunger 8 through an outer peripheral surface thereof. The rotation of the drive shaft 9 is converted into an advance / retreat operation of the plunger 8 via the rotary cam 10, and the intake and discharge of the fuel are performed by the advance / retreat operation of the plunger 8. The number of cam ridges (four in this embodiment) corresponding to the number of cylinders of the engine is formed on the outer peripheral surface of the rotary cam 10.

The pump body of the fuel pressurizing pump 1 has a pump block 11 in which the plunger 8 is accommodated.
And a shaft housing block 12 for rotatably housing a part of the drive shaft 9, and an outlet block 14 having suction and discharge passages 2 and 5, a discharge pressure regulating valve 13, and the like.

The pump block 11 is formed in a substantially cylindrical shape, and a bottomed cylindrical cylinder 16 is fitted to one end of the axial hole 15 and a blind lid 17 is fitted to the other end. Have been. A lateral hole 18 is provided on the other side surface of the pump block 11 so as to intersect with the axial hole 15. The lateral hole 18 allows the cam chamber 19 for accommodating the rotary cam 10.
And a bearing chamber 20 for accommodating the radial bearing 21 a are formed at the other end of the pump block 11. Cylinder 16
The cylinder hole 22 is arranged so as to open toward the cam chamber 19, and the base of the rod-shaped plunger 8 is slidably accommodated in the cylinder hole 22. The space between the bottom of the cylinder hole 22 and the base of the plunger 8 is a pump chamber 23, and the volume of the pump chamber 23 is increased or decreased by the reciprocating operation of the plunger 8. A supply / discharge hole 24 is formed in the cylinder 16 and the pump block 11, and supply / discharge of fuel to / from the pump chamber 23 is performed through the supply / discharge hole 24.

The axial hole 15 of the pump block 11
The cam chamber 19 is formed such that the diameter of the cam chamber 19 is larger than that of the cylinder fitting portion in a step-like manner. A metal bush 26 is provided on the peripheral wall of the lifter chamber 25.
Is press-fitted, and a bottomed cylindrical lifter 27 is slidably fitted in the bush 26. This lifter 27
The tip surface of the plunger 8 contacts the center of the inner surface of the bottom wall, and the outer peripheral surface of the rotary cam 10 directly contacts the outer surface of the bottom wall. The outer surface of the bottom wall is subjected to a surface treatment to improve the wear resistance of that portion. An annular spring seat 29 is attached to the distal end of the plunger 8 via a snap ring 28. The spring seat 29 and the lifter chamber 25
A spring 30 for urging the plunger 8 toward the rotary cam 10 is interposed between the upper wall and the upper wall.

In the figure, reference numeral 34 denotes a cam chamber 19 and a lifter chamber 2.
5 are conduction holes formed in the bottom wall of the lifter 27 to conduct the inside of the lifter 5.

A trapping groove 31 having a set width is formed on the outer peripheral surface of the plunger 8 at a substantially central portion, and the fuel leaked from the pump chamber 23 through the sliding gap between the plunger 8 and the cylinder 16 is trapped by the trapping groove 31. The captured fuel is transferred to the communication passage 3 formed in the cylinder 16 and the pump block 11.
2 to the suction passage 2 of the outlet block 14. Therefore, the capture groove 31 is maintained at the pressure of the suction passage 2, that is, the pressure regulated by the low-pressure regulator 4.

Further, an annular groove 57 is formed on the outer peripheral surface of the plunger 8 on the distal end side of the capture groove 31, and a rubber O-ring (elastic ring) 58 is formed in the annular groove 57.
Low coefficient of friction such as ethylene tetrafluoride resin and O
A seal ring 59 made of a resin material having a smaller elasticity than the ring 58 is housed in a polymerized state.

The annular groove 57 is provided with a first-step groove 57a having a set width.
And a second-step groove 57b formed at the center of the bottom surface of the first-step groove 57a so as to be narrower than the width of the groove 57a. The O-ring 58 is formed in a circular cross section, the seal ring 59 is formed in a thin cylindrical shape, and the axial length (width) of the seal ring 59 is longer than the axial length (diameter) of the O-ring 58. Is formed. The O-ring 58 is engaged with the second-step groove 57b of the annular groove 57, and the seal ring 59 is engaged with the first-step groove 57a.
When the ring 58 is housed in the second-step groove 57b, the arc-shaped top portion of the outer peripheral area projects radially outward from the groove 57b by a set amount. Therefore,
The seal ring 59 is formed by inserting the O-ring 58 into the second-step groove 57b.
When it is engaged with the first-step groove 57a in a state in which it is engaged with, the axially substantially central portion of the inner peripheral surface is pressed radially outward by the O-ring 58, and as a result, A substantially central portion in the axial direction swells and deforms into a mountain shape. And, the seal ring 59 is such that the plunger 8 is
In the state fitted to the cylinder hole, the bulge portion of the outer peripheral surface thereof is in close contact with the inner peripheral surface (sliding surface) of the cylinder hole 22, and the fuel captured by the capture groove 31 further flows into the cylinder hole 22 and the plunger 8. Leakage to the lifter chamber 25 through the gap is reliably prevented.

The inner peripheral surface (sliding surface) of the cylinder hole 22 and the lifter chamber are located at the tip of the cylinder 16 slightly closer to the cam chamber 19 than the maximum lowering position of the seal ring 59. Oil supply holes 6 communicating with each other
0 is formed. The oil supply hole 60 supplies the lubricating oil in the lifter chamber 25 with the seal ring 59 in the cylinder hole 22.
And the oil film is more easily formed on the outer peripheral surface of the seal ring 59.

On the other hand, the shaft housing block 12 is formed in a substantially cylindrical shape, and has a base portion formed with an enlarged diameter portion 35 which is fitted into the opening 18a of the lateral hole 18 of the pump block 11. The shaft hole 3 of the shaft housing block 12
The other end of the drive shaft 9 is fitted into 6, and a portion of the drive shaft 9 near the rotary cam 10 is rotatably supported on the inner periphery of the enlarged diameter portion 35 via a radial bearing 21b. That is,
The rotating cam 10 and one end of the drive shaft 9 are connected to the shaft housing block 1.
It protrudes outward from the second enlarged diameter portion 35. When the enlarged diameter portion 35 is fitted into the opening 18a, one end of the drive shaft 9 is supported by the pump block 11 via the radial bearing 21a, and the rotary cam 10 is housed in the cam chamber 19. Further, the distal end of the shaft housing block 12 is fitted and fixed in a mounting hole 38 formed in the upper side surface of the cylinder head 37 of the engine, and the other end of the drive shaft 9 protruding from the distal end of the block 12 is connected to a cup. It is connected to a camshaft 40 for driving the intake and exhaust valves via a ring 39.

Here, the pump block 11 is connected to a side portion of the cylinder head 37 by a bolt (not shown) along the direction of the drive shaft 9. At this time, the pump block 11 is insulated between the pump block 11 and the cylinder head 37. Material 66 is interposed. A through hole 66a is formed in the heat insulating material 66, and the heat insulating material 66 is tightened between the pump block 11 and the cylinder head 37 when the general portion of the shaft housing block 12 is fitted into the through hole 66a. Fixed. Therefore, the enlarged diameter portion 35 of the shaft housing block 12 is
The peripheral edge of a prevents the pump block 11 from falling out of the opening 18a.

Further, the shaft housing block 12 has radial bearings 21a and 21b, a cam chamber 19, and a lifter chamber 25.
For example, an oil passage 41 for circulating and supplying the lubricating oil is formed. One end of the oil passage 41 is opened to the outer peripheral surface of the distal end portion of the shaft housing block 12 to open the cylinder head 37.
Communicates with the upstream side of the oil gallery 42, and the other end is opened at the tip end surface of the shaft housing block 12 to
Communicates with the upper camshaft accommodating portion (downstream side of the oil gallery 42). Also, between the enlarged diameter portion 35 of the shaft housing block 12 and the opening 18a of the pump block 11,
Between the distal end of the shaft housing block 12 and the mounting hole 38 of the cylinder head 37, the distal end of the shaft housing block 12 and the drive shaft 9
Oil seals 45, 46, and 47 are interposed between the distal ends of the lubricating members, respectively, so that leakage of lubricating oil from these fitting gaps is reliably prevented by the oil seals 45, 46, and 47. I have.

As shown in FIG. 1, a supply / discharge chamber 48 communicating with the supply / discharge hole 24 of the pump block 11 is formed in the outlet block 14, and the suction passage 2 and the discharge passage 5 are connected to the supply / discharge chamber 48. It is formed so that it may communicate with.
A suction check valve 49 and a discharge check valve 50 are interposed in the vicinity of the supply / discharge chamber 48 of the suction passage 2 and the discharge passage 5, respectively, and the pump chamber 23 is operated by the cooperation of these check valves 49 and 50. The suction passage 2 and the discharge passage 5 are alternately opened.

Further, a return passage 51 for connecting the discharge passage 5 and the suction passage 2 is formed in the outlet block 14, and a passage is provided in the return passage 51 so as to maintain the pressure in the discharge passage 5 at a set pressure. Pressure regulating valve 13 that opens and closes
Is interposed. The discharge pressure regulating valve 13 includes a force of a spring 53 for urging a poppet 52 as a valve body in a valve closing direction and a discharge passage 5 acting on the poppet 52 in a valve opening direction.
The return passage 51 is opened by the balance with the fuel pressure on the side, and the substantial biasing force of the spring 53 acting on the poppet 52 is controlled by the solenoid 54 according to the load condition of the engine. ing.

A safety valve 55 is interposed in the discharge passage 5 so that when the pressure in the discharge passage 5 rises abnormally, the safety valve 55 opens to return the fuel in the discharge passage 5 to the suction passage 2. Has become.

In the above configuration, when the drive shaft 9 rotates integrally with the camshaft 40 when the engine is started,
The outer peripheral surface of the rotary cam 10 comes into rotational contact with the lifter 27, and the plunger 8 receives the operating force of the rotary cam 10 via the lifter 27, and moves up and down.

At this time, when the plunger 8 descends, the pressure in the pump chamber 23 becomes negative, and the fuel sent from the supply pump 3 opens the suction check valve 49 to sequentially pass through the supply / discharge chamber 48 and the supply / discharge hole 24. And is sucked into the pump chamber 23.
Then, when the plunger 8 rises thereafter, the pump chamber 2
3 and the fuel inside the supply / discharge holes 24 and the supply / discharge chamber 48 is pressurized to open the discharge check 50, and the pressurized fuel flows from the supply / discharge chamber 48 through the discharge passage 5 to the injector 6 of the fuel injection device. Supplied to. Further, the pumping action of the plunger 8 is continued, and when the pressure in the discharge passage 5 becomes equal to or higher than the set pressure, the poppet 52 of the discharge pressure regulating valve 13 opens the passage, and a part of the fuel in the discharge passage 5 is transferred to the suction passage 2. Then, the pressure in the discharge passage 5 is adjusted to the set pressure. As described above, this set pressure is variably controlled according to the engine load condition.

On the other hand, an oil pump (not shown) operates when the engine is started, and lubricating oil is sent to various parts in the engine by the oil pump. Then, a part of the lubricating oil is supplied to the oil passage 41 of the fuel pressurizing pump 1 through the oil gallery 43, and circulates in the cam chamber 19, the bearing chamber 20, and the lifter chamber 25 to circulate the cylinder head 37. Is discharged to the upper camshaft housing. As a result, lubricating oil is sufficiently supplied to the inside of the radial bearings 21a and 21b and the sliding surfaces of the rotary cam 10, the lifter 27, the plunger 8, and the like.

Incidentally, a part of the fuel pressurized in the pump chamber 23 tends to flow toward the lifter chamber 25 through the sliding gap between the plunger 8 and the cylinder 16. But,
At this time, most of the fuel that has entered the sliding gap between the plunger 8 and the cylinder 16 is captured by the capture groove 31 formed on the outer peripheral surface of the plunger 8, and is returned from the capture groove 31 to the suction passage 2 through the communication passage 32. It is. At this time, since the inside of the capture groove 31 is maintained at the suction pressure regulated by the low-pressure regulator 4 instead of the atmospheric pressure, the fuel in the capture groove 31 further passes through the sliding gap between the plunger 8 and the cylinder 16. The fuel flows in the direction of the lifter chamber 25 and the cam chamber 19, and the fuel flows through the rubber O-ring 58 disposed on the outer peripheral surface of the plunger 8 and the resin seal ring 59 having a smaller elasticity than the O-ring 58. Is surely blocked.

Since the back side of the seal ring 59 is pressed by the rubber O-ring 58, even if there is a slight dimensional accuracy, the seal ring 59 can be securely inserted into the inner peripheral surface of the cylinder hole 22. Be close. Also, the seal ring 5
9 is pressed by the O-ring 58 as described above, and the central portion of the outer peripheral surface in the axial direction swells radially outward, so that an oil film is easily formed on the swelling portion, and therefore the plunger Friction between 8 and cylinder 16 is kept small. Since the oil supply hole 60 that connects the inside of the cylinder hole 22 and the lifter chamber 25 is formed in the vicinity of the seal ring 59 of the cylinder 16, the lubricating oil in the lifter chamber 25 is reliably formed in the seal ring 59. Supplied.

The O-ring 58 and the seal ring 59
Are the first groove 57a and the second groove 5 of the annular groove 57, respectively.
7b, the positions of both are fixed, so that the contact state of the seal ring 59 with the cylinder hole 22 is always stable. Therefore, from this, plunger 8,
The sealing performance and lubrication performance between the cylinders 16 are also stabilized.
Further, the O-ring 58 is provided inside the annular groove 57 and the seal ring 5.
Since it is in close contact with the back surface of the fuel cell 9, leakage of fuel around the back surface of the seal ring 59 can be reliably suppressed.

The annular groove 57, the O-ring 58, the seal ring 59 and the like may be formed on the cylinder 16 side, and the structure of the fuel pressurizing pump is such that a plurality of plungers are provided around the rotary cam. They may be arranged radially.

Next, another embodiment of the present invention will be described with reference to FIGS.

The fuel pressurizing pump 101 of this embodiment is
In contrast to the embodiment shown in FIGS.
08 and the outer peripheral surface on the tip side of the capture groove 131 and the cylinder 1
Only the seal structure between the 16 inner peripheral surfaces is different, and the structure of the other parts is the same. Therefore, only the different portion will be described below, and the description of the other portions will be omitted.

An annular groove 157 is formed on the outer peripheral surface of the plunger 108 on the distal end side of the capture groove 131. As shown in FIG. 5, the annular groove 157 has a first width groove 157a having a set width. And a pair of second-stage grooves 157b, 15 arranged in the bottom of the first-stage groove 157a along the axial direction.
7c. The rubber O 2 having a circular cross section is provided in the second-step groove 157 b near the plunger base.
The ring 158 is housed therein, and the second-stage groove 15 near the distal end is accommodated.
7c accommodates a C-ring (metallic urging ring) 180 made of spring steel. The first-stage groove 157a has a thin cylindrical O-ring so as to cover the outer peripheral surfaces of both rings 158 and 180. A resin seal ring 159 having a smaller elasticity than the ring 158 is accommodated. The seal ring 159 is made of, for example, a resin having a small coefficient of friction, such as tetrafluoroethylene resin, and having a lower elasticity than the O-ring 158.

Here, when the O-ring 158 is housed in the groove 157b of the second step, the arc-shaped top of its outer peripheral area projects radially outward from the groove 157b. , C-ring 180 in its normal state has an inner diameter larger than the outer diameter of the bottom of the second-step groove 157c, and its outer peripheral surface is positioned radially outside the edge of the second-step groove 157c. It has become. Therefore, the seal ring 159 is pressed radially outward by the rubber O-ring 158 and the metal C-ring 180 in a state where the seal ring 159 is attached to the first-step groove 157a,
As a result, two portions of the outer surface along the axial direction bulge annularly outward in the radial direction. For this reason, the seal ring 1
In the state where the plunger 108 is fitted to the cylinder 116, the two bulges on the outer surface of the cylinder 59 are formed on the inner peripheral surface (sliding surface) of the cylinder 116 without strict dimensional accuracy control during manufacturing. Moving surface).

Since the fuel pressurizing pump 101 is configured as described above, the fuel flowing into the capture groove 131 at the time of operation of the pump passes through the sliding gap between the plunger 108 and the cylinder 116 and further flows toward the distal end of the plunger 108. At this time, the flow of the fuel is reliably prevented by the two bulges on the outer surface side of the seal ring 159 and the rubber O-ring 158 on the back side of the seal ring 159.

Here, since the expansion coefficient of the resin material is much larger than that of the metal material or the like, the change in contraction of the seal ring 159 due to the temperature change is large. For this reason,
The diameter of the seal ring 159 changes greatly at low temperatures and at high temperatures.
9, the O-ring 158 is crushed as shown in FIG. 5, and a gap is generated between the seal ring 159 and the cylinder 116. When the seal ring 159 is expanded at a high temperature and pressed against the inner peripheral surface of the cylinder 116, the seal ring 159 is deformed by so-called high-temperature creep, and the thickness thereof is reduced. When the seal ring 159 squeezes the O-ring 158 as shown in FIG.
There may be gaps between the sixteen.

However, in the case of this fuel pressurizing pump 101, since the rubber O-ring 158 and the metal C-ring 180 are arranged in the annular groove 157 of the plunger 108 along the axial direction, Even if the O-ring 158 is crushed for such a reason, the C
The ring 180 reliably presses the seal ring 159 against the inner surface of the cylinder 116, so that leakage of fuel from the outer surface side of the seal ring 159 can be prevented. Note that even when the O-ring 158 is crushed, the seal ring 1
Since the space between the rear surface of the seal ring 59 and the annular groove 157 is sealed by the O-ring 158, the fuel does not leak from the rear surface side of the seal ring 159.

FIGS. 6 and 7 show still another embodiment of the present invention. The fuel pressurizing pump 201 of this embodiment is the same as that of the embodiment shown in FIGS. The difference is that the seal component is mounted on the inner peripheral surface side of the cylinder 216 while the seal component is mounted on the outer peripheral surface side of the cylinder 108.

That is, this fuel pressurizing pump 201 has a first-stage groove 257 on the inner peripheral surface near the tip of the cylinder 216.
a and a pair of second-step grooves 257b and 257c are formed in the annular groove 257. In the annular groove 257, a resin seal ring 259 having a smaller elasticity than the O-ring 258, and a rubber O-ring 258, three members of a C ring 280 made of steel material are mounted. In the case of this pump 201 as well, the second-stage grooves 257b and 257c are provided along the axial direction at the bottom of the first-stage groove 257a, and the O-ring 25 is provided in the groove 257b near the base of the plunger 208.
8. The C-rings 280 are respectively housed in the grooves 257c near the tip, and in this state, these rings 258, 28
A seal ring 259 is accommodated in the first-stage groove 257a so as to cover the inner peripheral side of the inner ring 0. And O-ring 258
When housed in the groove 257b of the second step, the arc-shaped top of the inner peripheral area thereof projects radially inward from the groove 257b, and the C ring 280 has an outer diameter of the second diameter. Smaller than the inner diameter of the bottom of the step groove 257c, and
The inner peripheral surface is located radially inward of the edge of the groove 257c. For this reason, the seal ring 25
9 are pressed radially inward by a rubber O-ring 258 and a metal C-ring 280 in a state of being mounted in the first-step groove 257a, and as a result, the inner surface of the inner surface along the axial direction is Two places bulge in a ring radially inward,
The two bulging portions come into close contact with the outer peripheral surface (sliding surface) of the plunger 208.

Since the fuel pressurizing pump 201 is configured as described above, the inner peripheral surface of the seal ring 259 is pressed inward in the radial direction by the O-ring 258 and the C-ring 280, so that the plunger 208 is removed from the trapping groove 231. It is possible to stop the flow of the fuel that is going to flow out to the cam chamber side through the sliding gap of the cylinder 216, and to put the fuel that is going to enter between the back surface of the seal ring 259 and the annular groove 257 into a rubber O-ring 258. Can be surely dammed.

The resin seal ring 259 expands in diameter at high temperatures. However, if the O-ring 258 is set with time, the O-ring 258 is crushed by the seal ring 259 as shown in FIG. Thus, a gap is formed between the seal ring 259 and the plunger 208.
However, even in such a case, this pump 201
In the above, the C ring 280 made of steel material surely presses the seal ring 259 against the outer peripheral surface of the plunger 208, so that fuel does not leak from the gap between the seal ring 259 and the plunger 208. Of course, at this time, leakage of fuel from the gap between the back surface of the seal ring 259 and the annular groove 257 is prevented by the O-ring 258.

The embodiments of the present invention are not limited to those described above. For example, in the embodiments shown in FIGS. 4 and 5 and the embodiments shown in FIGS. Although the C-ring is used as the metal urging ring for pressing the circumstance, a garter spring or the like may be used instead of the C-ring.

[0053]

As described above, according to the first aspect of the present invention, an annular groove is provided on one of the sliding surfaces of the plunger and the cylinder, and the expansion and contraction is provided in the annular groove so as to be in close contact with the other sliding surface. A resin seal ring having low elasticity and an elastic ring having greater elasticity than the resin seal ring that presses the seal ring in the direction of the sliding surface on the other side are accommodated. Due to the pressing action, the seal ring with low sliding resistance is securely brought into close contact with the sliding surface on the other side. As a result, it is possible to reduce the cost and size and to use a structure that does not require strict dimensional accuracy. In spite of this, it is possible to reliably prevent the fuel from leaking from the sliding gap between the plunger and the cylinder without increasing friction between the plunger and the cylinder and reducing the durability of parts.

According to a second aspect of the present invention, in the first aspect of the present invention, since the elastic ring is formed of an O-ring made of rubber, a gap between the annular groove and the back surface of the seal ring is sealed by the elastic ring. As a result, it is possible to reliably prevent fuel from leaking through the back surface of the seal ring.

According to a third aspect of the present invention, in the first aspect of the present invention, the elastic ring is constituted by a rubber O-ring and a metal urging ring, and the O-ring and the urging ring are formed by shafts of a plunger and a cylinder. The gap between the annular groove and the back side of the seal ring is sealed by a rubber O-ring, while the seal ring is made of metal regardless of the set-off of the O-ring. The biasing ring ensures that the sliding surface is always in close contact with the sliding surface, and as a result, leakage of fuel from the seal ring portion can be more reliably prevented.

According to a fourth aspect of the present invention, in the third aspect of the present invention, the urging ring is constituted by a C-ring made of spring steel, so that the production cost and the space occupied by the seal ring are not increased. Leakage of fuel from the portion can be reliably prevented.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the axial length of the seal ring is formed to be longer than the axial length of the elastic ring. The resin-made seal ring having a smaller elasticity than the elastic ring is deformed into a mountain shape, and an oil film of lubricating oil is easily formed on the bulged outer peripheral surface. Therefore, the lubrication performance is further improved, and the friction between the plunger and the cylinder can be further reduced.

According to a sixth aspect of the present invention, in any one of the first to fifth aspects of the present invention, the annular groove is formed in a first-step groove in which the seal ring is engaged and a bottom portion of the first-step groove. And the second-stage groove in which the elastic ring is engaged, so that the contact position of the seal ring with the other sliding surface is always constant, and as a result, the sealing performance and the sliding performance are reduced. Stabilize.

According to a seventh aspect of the present invention, in any one of the first to sixth aspects of the present invention, lubricating oil is supplied to the seal ring in the vicinity of the position where the seal ring is provided on the sliding surface of the cylinder. To form the oil supply hole of
An oil film is more easily formed on the seal ring, and the lubrication performance between the plunger and the cylinder is improved.

According to an eighth aspect of the present invention, in any one of the first to seventh aspects of the present invention, the communication surface communicating with the low-pressure passage closer to the pump chamber than the position where the seal ring is provided on the sliding surface of the cylinder. Since the passage is formed, the fuel pressure acting on the seal ring portion is reduced, and as a result, leakage of fuel from the sliding gap between the plunger and the cylinder can be more reliably prevented.

[Brief description of the drawings]

FIG. 1 is a sectional view taken along line AA of FIG. 2 showing one embodiment of the present invention.

FIG. 2 is a horizontal sectional view showing the embodiment.

FIG. 3 is a sectional view taken along the line BB of FIG. 1 showing the embodiment.

FIG. 4 is a sectional view showing another embodiment of the present invention.

FIG. 5 is an enlarged sectional view of a portion C in FIG. 4 showing the same embodiment.

FIG. 6 is a sectional view showing still another embodiment of the present invention.

FIG. 7 is an enlarged sectional view of a portion D in FIG. 6 showing the same embodiment.

[Explanation of symbols]

1, 101, 201 ... fuel pressurizing pump 2 ... suction passage (low pressure passage) 8, 108, 208 ... plunger 10 ... rotary cam 16, 116, 216 ... cylinder 23 ... pump chamber 32 ... communication passage 57a, 157a, 257a ... First-stage grooves 57b, 157b, 157c, 257b, 257c: Second-stage grooves 57, 157, 257: Annular grooves 58, 158, 258: O-rings 59, 159, 259: Seal rings 60: Oil supply holes 180 , 280 ... C ring (metal biasing ring)

 ──────────────────────────────────────────────────続 き Continued on front page (72) Inventor Hiroyuki Watanabe 1370 Onna, Atsugi-shi, Kanagawa Prefecture

Claims (8)

[Claims] A plunger is slidably housed in a cylinder, a pump chamber for pressurizing fuel is formed between the cylinder and the plunger, and a rotation for moving the plunger forward and backward outside the cylinder. In a fuel pressurizing pump in which a cam is disposed, an annular groove is provided on one of the sliding surfaces of the plunger and the cylinder, and a small elasticity is provided in the annular groove so as to be in close contact with the other sliding surface. A fuel pressurizing pump containing a resin seal ring and an elastic ring having a greater elasticity than the resin seal ring for pressing the seal ring in the direction of the sliding surface on the other side. . 2. The fuel pressurizing pump according to claim 1, wherein the elastic ring is constituted by an O-ring made of rubber. 3. The elastic ring comprises an O-ring made of rubber and an urging ring made of metal, and the O-ring and the urging ring are arranged side by side along the axial direction of the plunger and the cylinder. The fuel pressurizing pump according to claim 1. 4. The fuel pressurizing pump according to claim 3, wherein said urging ring is constituted by a C-ring made of spring steel. 5. The fuel pressurizing pump according to claim 1, wherein an axial length of the seal ring is longer than an axial length of the elastic ring. 6. The first groove in which the seal ring is engaged, and the second groove formed in the bottom of the first groove and in which the elastic ring is engaged. The fuel pressurizing pump according to any one of claims 1 to 5, comprising: 7. An oil supply hole for supplying lubricating oil to the seal ring is formed in the sliding surface of the cylinder near a position where the seal ring is provided. 7. The fuel pressurizing pump according to any one of 1 to 6. 8. A communication passage communicating with the low-pressure passage on a sliding surface of the cylinder closer to a pump chamber than a position where the seal ring is provided.
The fuel pressurizing pump according to any one of claims 1 to 7.