JPS6245969A - Fuel injection pump - Google Patents

Abstract

PURPOSE:To reduce the load applied onto an oil seal by setting nearly equal to pressure of the lubricating oil supplied into an oil resevoir formed onto the outer periphery of a drive shaft to the pressure of the fuel supplied into the space between the oil seal on one side and a feed pump. CONSTITUTION:The fuel pressurized by a feed pump 101 is pressure-adjusted by a regulating valve 120 and introduced into a pump mechanism chamber 109, and at the same time leaks into the left-side space 112 of the pump 101. The leaked fuel is introduced into the suction side of the pump 101 through a passage 104. At this time, the intrusion of the fuel in the space 112 into a bearing 102a side is suppressed by an oil seal 103a. While, lubricating oil intrudes into an oil reservoir 105 from an introducing passage 113 through a throttle 111, and lubricates journal bearings 102a and 102b. Though, in this case, the intake negative pressure of the fuel and the discharge back-pressure of lubricating oil act onto the both sides of the oil seal 103a, each of which is low pressure close to the atmospheric pressure, and a prescribed purpose can be achieved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fuel injection pump, and more particularly to a distribution type fuel injection pump for diesel.

[Conventional technology]

Conventionally, distribution type pumps, which have been widely used as fuel injection pumps for diesel engines, are designed to rely entirely on the viscosity of the fuel itself for lubrication of the internal mechanism.

FIG. 3 is a vertical sectional view showing the overall configuration of a conventional distribution type fuel injection pump, in which 110 is a drive shaft, 101 is a feed pump, 102a and 102b are journal bearings provided at both ends of the drive shaft, and 103b is a It is an oil seal. 305 is the drive shirt number 1
A fuel passage 304 is for lubricating the fuel passage 3.
This is the passageway that connects to 05. 306 is a pump plunger ring, 309 is a feed pump cover, 310 is a face cam, 311 is a fly weight, 312 is a cabana reha, 313 is a fuel cut solenoid, 31
4 is a delivery valve, 315 is a branching device, 316 is a spill ring, 317 is a plunger spring, 318 is a cam plate, 319 is a roller, and 320 is an adjusting device.

[Problem that the invention seeks to solve]

In recent years, in diesel engines, there has been an increasing need to use other fuels instead of light oil, such as gasoline, kerosene, alcohol, and other fuels with low viscosity, that is, with poor lubricity. However, when a low-viscosity fuel such as gasoline or alcohol is used in a conventional distribution-type injection pump that relies on the fuel itself for lubrication, the drive shaft 110 and journal bearing 10 suffer from particularly large sliding loads due to poor lubricity.
2b and 102a is significant, friction powder is sucked into the pump mechanism chamber 109 through the passage 304, and the plunger 30
6. There is a problem in that it gets into the cylinder 307, spill ring 3o8, and other sliding parts and rolling parts, causing permanent damage such as seizure.

[Means for solving problems]

The present invention provides an oil seal on the outside of each bearing provided at both ends of an oil pool formed on the outer periphery of a drive shaft, and a small space is provided between the oil seal on the right side and the feed pump, so that oil can be kept in the oil pool. The pressure of the lubricating oil flowing by the pump is made approximately equal to the pressure of the fuel flowing into the space.

[Effect]

On the right side 17), the difference in pressure (differential pressure) applied to both the left and right ends of the oil seal is minute, so the load on the oil seal is minute, and the oil seal is not damaged and the drive shaft is well lubricated. Can be done.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention shown in the drawings will be described.

FIG. 1 is a longitudinal cross-sectional view showing the overall structure of a first embodiment of a fuel injection pump according to the present invention, in which a drive shirt 10 is rotatably assembled by Jarre bearings 102a and 102b. Oil seals 103a and 103b are provided on the right side of the bearing 102a and the left side of the bearing 102b, respectively, to prevent oil leakage from the oil reservoir 105. The drive shaft 110 is rotationally driven at its left end by an engine (not shown).

A feed pump 101 is assembled on the right side of the shaft 110, and the right side thereof is connected to an injection pump main body mechanism, which is the same as the conventionally known mechanism shown in FIG. Therefore, the explanation will be omitted.

A small space 112 is provided between the oil seal 103a and the feed pump 101, and this space 112 is connected to the passage 10.
4 communicates with the suction side of the feed pump 101. A lubricating oil introduction passage 113 and a lubricating oil discharge passage 114 communicate with the oil reservoir 105, and the introduction passage 113 also has a throttle 1.
11 is provided. The inlet passage 113 is connected to an oil pump of an engine (not shown), and the discharge passage 114 is connected to an oil pan.

” To explain the operation of the fuel injection pump of the present invention having the configuration as described above, the fuel pressurized and discharged by the feed pump 101 is pressure regulated by the regulator valve 120 and enters the pump mechanism chamber 109. At the same time, the fuel is discharged by the feed pump 101.
leaks little by little into the space 112 on the left side of 1.

Then, the leaked fuel is guided from the space 112 through the passage 104 to the suction side of the feed pump 101 and is re-inhaled. The fuel in this space-time 112 is the oil seal 103a
It is prevented from entering the bearing 102a side. On the other hand, lubricating oil supplied by an oil pump of the engine (not shown) enters the oil reservoir 105 through the introduction path 113 while its flow rate is regulated by the throttle 111 . This lubricating oil provides good lubrication for the journal bearings 102a and 102b. Furthermore, the lubricating oil overflowing from the oil reservoir 105 is discharged through the discharge passage 114 to an oil pan of the engine (not shown).

In the above configuration, fuel suction negative pressure acts on the right side of the oil seal 103a, and lubricant discharge back pressure acts on the left side, but both are low pressures close to atmospheric pressure, so
The load (differential pressure) applied to the oil seal 103a becomes very small, and the durability of the oil seal 103a is not impaired.

As described above, it is possible to perform good lubrication of the drive shaft without impairing the durability of the oil seal.

Next, FIG. 2 is a longitudinal sectional view showing the overall configuration of a second embodiment of the fuel injection pump according to the present invention, in which the discharge passage 114 communicates with a control chamber 213 of a pressure regulating valve device 220. The pressure detection chamber 214 of the pressure regulating valve device 220 communicates with the pump mechanism chamber 109 through a pressure guiding path 2]5.

The valve device 220 is composed of a cylinder 216 and a spool 210, and the spool 210 is fitted into the cylinder 216 so as to be slidable left and right and in an oil-tight manner.

A T-junction 211 is provided in the spool 210, and the cylinder 21
6 is provided with an annular groove 217, and these T-junctions 211 and annular grooves 217 are associated so as to communicate only when the spool 210 moves to the right. The groove 217 communicates with an oil pan (not shown) through a second discharge path 212. Oil seal 103b and journal bearing 10
The space 207 between 2b communicates with the second discharge path 212 through the passage 21B. A space 112 between the feed pump 101 and the oil seal 103a communicates with the discharge side of the feed pump 101 through a passage 209. Reference numeral 111 is a throttle provided in an introduction path 113, and this introduction path 113 communicates with an oil pump of an engine (not shown).

The configuration other than the above is the same as the configuration of the first embodiment shown in FIG.

Next, the operation of the fuel injection pump of the present invention having the above structure will be explained. The structure of this second embodiment is different from that in the first embodiment shown in FIG. This is used when it is not possible to provide 104 due to the design.

A space 112 between the feed pump 101 and the oil seal 103a is communicated with the discharge side of the feed pump 101 (that is, the high pressure side, which has the same pressure as the inside of the pump mechanism chamber 109) through a passage 209. Therefore, when the pump starts rotating, high fuel pressure acts on the right end surface of the oil seal 103a.

At the same time, high fuel pressure also acts on the right end surface of the spool 210 in the pressure regulating valve device 220, moving the spool 210 to the left and closing the communication between the T-junction 211 and the groove 217. On the other hand, similarly to the first embodiment, the aperture 111
The lubricating oil introduced into the oil pool 105 through the introduction path 113 flows out to the discharge path 114. However, as described above, since the T-junction 211 and the groove 217 are in a closed state, the pressure of the lubricating oil flowing into the control chamber 213 increases, and at the same time, the pressure in the oil reservoir 105 also increases. When the pressure of the lubricating oil flowing into the control chamber 213 eventually exceeds the pressure inside the pump mechanism chamber 109, the force acting on the left end surface of the spool 210 becomes greater than the force acting on the right end surface, and the spool 210 moves to the right. will be moved. At the same time, the T-junction 211 and the groove 217 are unblocked and communicate with each other, so the lubricating oil in the control chamber 213 is discharged from the groove 217 to the discharge path 212-
flows into the oil pan. Therefore, the pressure in the control chamber 213 does not increase any further and is maintained at the same pressure as the pressure in the pressure detection chamber 214.

As described above, in the pressure regulating valve device 220, both the left and right end surfaces of the spool 210, that is, the control chamber 213 and the pressure detection chamber 21
4 is maintained at the same pressure, which means that the lubricating oil in the oil reservoir 105 and the fuel pressure in the space 112 are maintained at the same pressure.In other words, the oil seal 103a
It is inevitable that the differential pressure acting on the left and right end surfaces of is O.

Therefore, under any operating conditions, the oil seal 10
No load is applied to the oil seal 103a, and the durability of the oil seal 103a can be ensured.

On the other hand, the lubricating oil in the oil pool chamber 105 leaks into the space 207 through the gap between the left journal bearing 102b, but this lubricating oil passes through the passage 218 and enters the discharge passage 212.
Since the oil is discharged to the oil seal 103b, no load is applied to the oil seal 103b.

As described above, the drive shaft can be well lubricated without impairing the durability of the oil seal.

Note that the pressure regulating valve device in the second embodiment shown in FIG. It may also be possible to communicate with or block it.

Further, although the pressure regulating valve 220 uses the spool 210, it may also use a diaphragm.

Further, in the first and second embodiments, all the bearings were journal bearings, but except for the left bearing 102b in the second embodiment shown in FIG. 2, bearings such as needle bearings were used. You can.

Further, in the second embodiment, the pressure guiding path 215 is connected to the pump mechanism chamber 109, but this pressure guiding path 215
5 may be configured to communicate directly with the space 112. In this case, passage 209 is not required. Furthermore, in both of the above embodiments, the lubricating oil introduction path 113 is provided with the throttle 111, but the restriction 111 may be omitted and the introduction path 113 may be directly connected to the sliding gap of the journal bearing.

〔Effect of the invention〕

In the fuel injection pump according to the present invention, since the load applied to the oil seal of the drive shaft is minimized, it is highly effective in providing good lubrication of the drive shaft without impairing the durability of the oil seal. Yes, and conventionally,
By making it possible to use this low-viscosity fuel in distribution-type fuel injection pumps, which have previously been considered impossible to use paper-viscous fuels such as alcohol, it is now possible to use alcohol fuel in small, high-speed engines with a small, lightweight, and inexpensive distribution system. This has the advantage that a type fuel injection pump can be applied.

[Brief explanation of drawings]

FIG. 1 is a vertical sectional view showing the overall configuration of a first embodiment of the fuel injection pump according to the present invention, FIG. 2 is a vertical sectional view showing the overall configuration of the second embodiment of the fuel injection pump according to the present invention, FIG. 3 is a longitudinal sectional view showing the overall configuration of a conventional distribution type fuel injection pump, and the same reference numerals in the figure indicate the same or equivalent parts. 110... Drive shaft, 101... Feed pump, 102a, 102b... Journal bearing (bearing), 103a. 103b...Oil seal, 112...Space, 10
4...Aisle. 105... Oil pool, 111... Squeezing, 113...
・Inlet path, 114... Discharge path, 109... Pump mechanism chamber, 120... Regulate valve, 209...
Passage, 220...pressure regulating valve device. 211... crossroads, 210... spool, 212...
...Second discharge path, 213...Control room, 214...
Pressure detection chamber, 215... Pressure path, 216... Cylinder,
217... Annular groove, 218... Passage. 207...Space.

Claims (4)

[Claims] (1) Bearings (102a, 10
2b) oil seals (103a, 103b) at the outer end of
A small space (112) is provided between the right oil seal (103a) and the feed pump (101),
A fuel injection pump characterized in that the pressure of lubricating oil flowing into the oil reservoir (105) by an oil pump of an engine and the pressure of fuel flowing into the space (112) are made approximately equal. (2) In the distribution type fuel injection pump for diesel engines, an oil seal (103a) is provided between the feed pump (101) and the bearing (102a) on the side closer to the feed pump (101).
a) and the space (112) between the feed pump (101)
) is connected to the suction side of the feed pump (101), and an oil sump (
105) is provided with an inlet passage (113) and an outlet passage (114) in communication with each other, and the inlet passage (113) is connected to an oil pump. fuel injection pump. (3) In the distribution type fuel injection pump for diesel engines, the feed pump (101) and the feed pump (1
An oil seal (103a) is provided between the bearings (102a) on the side closer to Communication, two bearings (1
02a, 102b), an inlet path (113) and a discharge path (114) are communicated with each other.
Connect the discharge path (114) to the pressure control valve device (220), and connect the atmospheric side oil seal (103b) and the bearing (102b).
Claim 1, characterized in that the space (207) between is connected to the second discharge passage 212 through a passage 218, and the introduction passage (113) is connected to an oil pump of the engine.
The fuel injection pump described in section. (4) The fuel injection pump according to claim 3, wherein the pressure control valve device is provided with a spool valve or a diaphragm valve.