JPH01134062A - Distributor type fuel injection pump - Google Patents

Abstract

PURPOSE:To prevent lubricating oil in a cam case from mixing in fuel via a fuel recovery passage as well as to solve a problem of loading on a fuel filter by installing a pressure control valve, raising the extent of hydraulic pressure in the fuel recovery passage, in a passage being interconnected to the fuel recovery passage or the cam case. CONSTITUTION:Fuel in a tank 2 is fed to a gallery 5 by a feed pump 1 via a pressure regulating valve 3 and then it is fed to a plunger chamber 9. When a roller 13 moves along an inner cam 14 with rotation of a rotor 7, a plunger 8 reciprocates via a shoe 12, thereby taking in and discharging the fuel. In this constitution aforesaid, each of ring grooves 34, 35 is formed in each sliding surface of the plunger 8 and a cylinder, while these ring grooves 34, 35 are interconnected to the feed pump 1 via respective fuel passages 37-40. Then, a pressure control valve 50 is connected to an interval between one fuel passage 40 and a lubricating oil passage 49. With this constitution, lubricating oil in a cam case 32 is prevented from mixing in the fuel.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an inner cam type fuel distribution pump, and more specifically to a distribution pump in which a cam chamber formed by an inner cam and a rotor is lubricated with lubricating oil other than fuel. Regarding fuel injection pumps.

[Prior Art] As social demands for fuel efficiency have increased, efforts have been made to improve the injection pressure of fuel injection pumps. In place of this configuration, a so-called inner cam type in which the inner surface of the circumference is used as a cam surface has been proposed (for example, Japanese Patent Laid-Open No. 61-96168). Such an inner cam type distribution fuel injection pump has a t? A freely movable plunger is driven by the cam profile of the inner cam, and fuel is injected by compression of the fuel by the plunger.

These inner cam type distribution fuel injection pumps can have multiple plungers that pump fuel, so
This is advantageous in terms of increasing the injection pressure.

[Problems to be Solved by the Invention] However, the use of kerosene/alcohol mixed fuel, which has recently been considered for use as a fuel for diesel engines in addition to light oil, requires high pressure in the − layer of the fuel injection pump. This results in durability problems.

In other words, higher pressure of the injected fuel increases the contact pressure between the inner cam and the plunger that moves along its cam profile, causing the inner cam, the roller that slides on the inner cam, the shoe that rotatably holds the roller, etc. Increase load stress.

Conventionally, the cam chamber that houses these parts has been lubricated with fuel oil, but when used under such high loads, the lubrication becomes insufficient and the parts wear out, leading to deterioration of pump characteristics and durability. This may lead to problems such as deterioration.

In order to solve this problem, the present inventors have proposed in a previous application a lubrication mechanism that lubricates the cam chamber with lubricating oil having a higher viscosity than fuel.

However, with this type of fuel injection pump that lubricates the cam chamber with lubricating oil other than fuel, there is a problem that the lubricating oil leaks from the sliding part between the two chambers and mixes with the fuel. ing.

For example, referring to a cross-sectional view of the rotor, timer, and their surroundings of a fuel injection pump shown in FIG. The plunger 107 is fitted into the fitting hole 105 of the inner cam 103, and by aligning the roller 111 housed in the shoe 109 along the cam face 101a of the inner cam 101, the plunger 107 is reciprocated in the radial direction, and the fuel in the plunger chamber 113 is pumped. do. A timer 120 is provided as a mechanism for changing the injection time by moving the inner cam 101 in the rotational direction. This timer 120 has pressure chambers 123 and 125 formed on both sides of the timer piston 121, and the timer piston 121 is moved by the balance of the hydraulic pressure in these chambers and the force of the spring 127, and the inner cam is connected via the piston pin 129. 101 is rotated. However, in this device, the piston pin 129 is removed from the cam chamber 131.
Lubricating oil leaks through the outer peripheral sliding surface of the timer piston 121 and the outer peripheral sliding surface of the timer piston 121 . This leaked lubricating oil is likely to get mixed into the fuel recovery passage 133 for recovering fuel leaked from the pressure chambers 123 and the like. Therefore, there was a problem in that a fuel filter (not shown) communicating with the fuel recovery passage 133 was clogged.

Regarding face cam type fuel injection pumps, one in which a pressure mechanism with a plunger chamber and a cam chamber are separated is known, for example, from Japanese Utility Model Application No. 61-43952; Since the two chambers are separated by a sealing member, many sealing members are required to obtain a sufficient sealing effect, which complicates the structure, and also prevents smooth movement of the sliding parts. was there.

The present invention has been made in order to solve the problems of the above-mentioned conventional technology, and can prevent the lubricating oil in the cam chamber from entering the fuel through the fuel recovery passage, thereby eliminating clogging of the fuel filter. The purpose of the present invention is to provide an inner cam type distribution type fuel injection pump.

[Means for Solving the Problems] The distribution type fuel injection pump of the present invention includes an inner cam whose inner periphery is a cam surface, and a drive shaft that is disposed inside the inner cam and that rotates relative to the inner cam by rotation of a drive shaft. and at least two rotors that slide in an oil-tight manner within a fitting hole formed in a radial direction of the rotor.
In the distribution type fuel injection pump, the inner cam and The surrounding area is lubricated in an oil-tight state with a lubricating oil other than fuel in the cam chamber, and the fuel leaking from the sliding parts of the plunger chamber and its peripheral equipment is removed through a route different from the fuel route that is pumped from the plunger chamber. A fuel recovery passage is provided to collect the fuel. Alternatively, the passage communicating with the cam chamber is provided with a pressure control valve which makes the after pressure of both passages equal or slightly increases the fuel pressure of the fuel recovery passage.

[Function] In the distributed fuel injection pump of the present invention, the rotor rotates relative to the inner cam due to the rotation of the drive shaft, and as the rotor rotates, the plunger moves radially inside the fitting hole along the cam profile of the inner cam. The fuel is pumped by sliding in the direction. Moreover, in the distribution type fuel ITi pump of the present invention, the lubrication mechanism lubricates the inside of the cam chamber including the inner cam and rotor using lubricating oil other than fuel. Therefore,
Sufficient lubrication between the inner cam and rotor of a high-pressure distribution fuel injection pump is ensured by a lubricating oil other than fuel, for example a lubricating oil with a higher viscosity than fuel.

Further, fuel leaked from the plunger chamber or the like is recovered via a fuel recovery passage.

Furthermore, since this pump is equipped with a pressure control valve between the fuel recovery passage and the passage communicating with the cam chamber, the hydraulic pressure in the fuel recovery passage and the cam chamber becomes equal, or the pressure in the fuel recovery passage is higher. Therefore, the lubricating oil is prevented from leaking into the fuel recovery passage from the sliding portion between the cam chamber and the fuel recovery passage and mixing with the fuel.

[Embodiments] In order to further clarify the structure and operation of the present invention described above, preferred embodiments of the inner cam distribution type fuel injection pump of the present invention will be described below.

FIG. 1 is a side sectional view of a fuel injection pump for a diesel engine, and FIG. 2 is a sectional view taken along line AA in FIG.

As shown in the figure, the inner cam type distribution type fuel injection pump of the present embodiment including the feed pump 1 is of an electromagnetic spill metering type. The configuration will be briefly explained below along the flow of fuel.

The feed pump 1 connects the tank 2 with the fuel filter IA,
The fuel is pumped up through a fuel pump IB that compensates for the loss of fuel pressure in the fuel filter IA, and the pumped fuel is pressure regulated by a pressure regulating valve 3 and supplied to a gear gallery 5 in the head 4. The fuel in the gearbox 5 is introduced into a plunger chamber 9 formed by the plunger 8 via a passage 6a in the cylinder 6 and a passage 7a in the rotor 7. The rotor 7 is slidably fitted into the cylinder 6, held by a bearing 10, and rotated by the engine.

Further, a plurality of fitting holes 7A are formed in the outer periphery of the rotor 7 in the radial direction of the rotor 7, and a plunger 8 is slidably fitted into each of the fitting holes 7A. A shoe 12 is attached to a roller 13 at the radially outer end of the plunger 8.
It is arranged so that it can be freely rotated. An inner cam 14 having cam ridges formed on its inner surface is disposed on the outside of the rotor. Since the plunger chamber 8 is urged in the outer circumferential direction by the pressure of the fuel, the roller 1 at the end of the plunger 8
3 is always in contact with the cam profile of the inner cam 14. Therefore, when the roller 13 moves along the cam profile formed on the inner circumferential surface of the inner cam 14 due to the rotation of the rotor, the roller 13 performs reciprocating motion in the radial direction based on the cam surface, and this movement of the roller 3 is caused by the movement of the shoe 12. is transmitted to the plunger 8 through. Here, the stroke in which the plunger 8 moves outward in the radial direction of the rotor 7 is a suction stroke, and the stroke inward is a discharge stroke.

The passage 6a in the cylinder 6 and the passage 7 in the rotor 7 described above
The circumferential positional relationship with a is such that the inner passage communicates during the fuel suction stroke due to movement of the plunger 8 in the inner circumferential direction due to rotation of the rotor, and closes during the compression stroke. Furthermore, the rotor has a plunger chamber 9.
A spill boat 15 and a discharge port 16 are provided, which communicate with the passage 17.1 provided in the cylinder 6 during the discharge stroke. An electromagnetic spill valve 19 is disposed at the end of the passage 17, and communicates and shuts off the passage 17 and the gear assembly 5. The electromagnetic spill valve 19 operates based on a signal indicating the operating state of the engine, such as a signal from the accelerator opening sensor 20 or a signal from the rotation angle sensor 21.
It is driven by the CU22. In addition, the passage 1 in the cylinder 6
Delivery valve 24 via passage 23 in head 4
It communicates with the nozzle installed in the engine through a vibrator.

With the above configuration, when the rotor 7 rotates due to the rotation of the engine, the plunger 8 repeats the suction stroke in which the fuel is sucked in through the gear assembly 5 and the compression stroke in which the fuel is delivered to the fuel injection valve through the delivery valve 24. In synchronization with this, the overflow timing is adjusted by the electromagnetic spill valve 19, that is, the fuel injection amount is controlled.

Adjustment of the fuel injection timing thus made is performed by a timer as clearly shown in FIG. That is,
The inner cam 14 is connected to a timer piston 26 via a slide pin 25, and as the timer piston 26 moves, the inner cam 14 is rotated and displaced. That is, in the timer, a pressure chamber 27 is formed at one end surface of a timer piston 26, and the pressure chamber 27 and the gear assembly 5 communicate with each other through a passage 28. A low pressure chamber 29 is formed on the other end surface of the timer piston 26, and a spring 30 is disposed to bias the timer piston 26 toward the pressure chamber 27. Further, the low pressure chamber 29 communicates with a cam chamber 32 in which the inner cam 14 is housed through a communication hole 31 provided in the timer piston 26.

Therefore, the timer piston 26 is moved by the force received by the timer piston 26 due to the pressure inside the pressure chamber 27, the pressure inside the low pressure chamber 29, and the biasing force of the spring 30.
Its position is controlled by the balance with the force it receives. The pressure chamber 27 of the timer communicates with the gear gallery 5, and fuel whose pressure is regulated by the pressure regulating valve 3 is introduced into the pressure chamber 27 of the timer. Since the pressure regulating valve 3 generates high pressure as the rotation speed increases, the timer piston 26 moves into the low pressure chamber 29 as the rotation speed increases.
Displaced to the side.

Next, a mechanism related to the recovery means for fuel leaked from the plunger chamber 9, the timer, etc. and lubrication in the cam chamber 32 will be explained, and a mechanism for preventing mixing of fuel and lubricating oil as a characteristic structure of this embodiment will be explained. do.

An annular @ 34 is formed on the sliding surface of each plunger 8 and functions as a leak fuel recovery groove.

Furthermore, an annular groove 35 that similarly functions as a leak fuel recovery groove is formed on the sliding surface of the cylinder 6 on which the rotor 7 slides. Further, an annular groove 36 that similarly functions as a leak fuel recovery groove is formed on the pressure chamber 27 side of the sliding surface of the timer piston 26. These annular grooves 34, 35, 36 for recovering leaked fuel are connected to fuel passages 37.
38, 39, and 40, it is communicated with the fuel suction side of the feed pump 1, that is, the low pressure side. Therefore, due to the annular grooves 34, 35, 36 for recovering leaked fuel, even if part of the fuel leaks through the minute gap between the plunger 8 and rotor 7 or the outer circumference of the timer piston 26 during fuel injection, These can be collected and returned to the fuel tank 2.

Next, the lubrication of the cam chamber 32 will be explained. Lubricating oil is supplied to the cam chamber 32 from the lubricating system of the engine (not shown) via the ridge 41. A portion of the lubricating oil is also introduced between the two bearings 10 that support the rotor 7, and the lubricating oil that flows out between the rotor 7 and the bearings 10 is directly introduced into the cam chamber 32 or via the passage 42. The person is exiled to the cam room 32.

A lubricating oil outlet 430ut is provided at the lower part of the cam chamber 32 as shown in the figure, and the lubricating oil flowing from the lubricating oil group 43 through the crest 41 is delivered to the inner cam 14, roller 13, shoe 12.
After lubricating them and removing frictional heat by cooling them, the lubricating oil flows out from the lubricating oil outlet 43 out to the lubricating system of the engine (not shown).

Further, as a special effects configuration of this embodiment, a pressure control valve 50 is installed between the fuel passage 40 and the lubricating oil passage 49 connected to the lubricating oil outlet 43 out as a mechanism to prevent the lubricating oil from mixing with the fuel. is connected. This pressure control valve 50
As shown in an enlarged view in FIG. 3, a spool 53 is slidably fitted into a valve body 51.
Liquid chambers 55 and 57 are formed on both sides of 3, respectively.

One of the liquid chambers 55 has a fuel boat 59 connected to the fuel passage 40 , and the other liquid chamber 57 has a lubricating oil boat 61 connected to the lubricating oil passage 49 . The side of the valve body 51 is the passage 4.
Fuel discharge boat 63 connected to tank 2 via 0a
However, a lubricating oil discharge boat 65 connected to the oil pan 64 via a passage 49a is formed.

Next, the operation of the pressure control valve 50 will be explained.
When the spool 53 of the pressure control valve 50 is in the neutral position as shown, the hydraulic pressure applied to both sides of the spool 53 is equal, and the sides of the spool 53 close the fuel discharge boat 59 and the lubricant discharge boat 65. This results in
The cam chamber 32 and the fuel passage 40 are cut off from the atmosphere.

From this state, for example, if the hydraulic pressure of the lubricating oil on the cam chamber 32 side becomes higher than that on the fuel passage 40 side, the pressure control valve 5
The spool 53 of No. 0 moves upward in the figure, and the lubricating oil passage 4
9 and a lubricating oil outlet boat 65, which communicates with the oil pan 6/1 via a passage 49a. As a result, the lubricating oil is collected into the oil pan 64, and the hydraulic pressure in the cam chamber 32 is reduced. Therefore, the liquid pressure in the liquid chamber 55 becomes higher than that in the liquid chamber 57, and the spool 53 moves downward in the drawing.

The operation of the spool 53 is stopped when the hydraulic pressures in the rear chamber 55 and the hollow chamber 57 become equal.

Therefore, the lubricating oil pressure in the cam chamber 32 becomes equal to the oil pressure on the fuel passage 40 side. Therefore, the hydraulic pressures in the cam chamber 32 and the annular groove 36 as a fuel recovery groove become equal through both liquid chambers 55 and 57, so lubricating oil flows from the cam chamber 34 through the gap between the piston pin 25 and the housing 44 into the annular groove. There will be no leakage in the groove 36. Therefore, since the lubricating oil does not get mixed into the fuel, the fuel filter IA is not clogged with the lubricating oil mixed into the fuel.

Next, another embodiment will be explained with reference to FIG.
will be returned to. On the other hand, the fuel passage l↓9A for discharging lubricating oil from the cam v32 is connected directly to the oil pan 64.
It is connected to the.

Therefore, the fuel passage 4OA and the passage 49Δ are
Since both are open to the atmosphere, the pressure at the outlet is almost the same, but there is a check valve 7 only in the passage 4OA.
0, the fuel pressure in the recovery passage such as the annular groove becomes higher than the lubricating oil pressure in the cam chamber 32 by the force generated by the spring of the check valve 70. Therefore, as in the above embodiment, it is possible to prevent the lubricating oil from getting mixed into the fuel.

Although the embodiments of the present invention have been described above, the present invention is not equally limited to these embodiments, and may include the following modifications.

■ Instead of the pressure control valve 50 in FIG. 3, springs 80 and 82 with equal spring force are provided in the pressure control valve 50Ac7]a chambers 55A and 57A as shown in FIG. 5 to stabilize the movement of the spool 53. You may let them.

■ By not using the spring in the liquid chamber on the side communicating with the fuel passage of the pressure control valve 50A in Fig. 5 and using only the spring in the other liquid chamber, it is possible to achieve the same effect as the reverse valve shown in Fig. 4. It may be configured to function.

(2) Alternatively, the pressure receiving area of the spool of the pressure control valve on the side communicating with the fuel passage may be made smaller than the other side, thereby achieving the same check valve function as in (2) above.

[Effects of the Invention] As described in detail above, the inner cam type distribution fuel injection pump of the present invention can prevent the lubricating oil in the cam chamber from entering the fuel via the fuel recovery passage, and can prevent the lubricating oil from entering the fuel filter. can eliminate clogging.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of an inner cam type distribution type fuel injection pump as an embodiment of the present invention, and FIG.
3 is a sectional view showing the pressure control valve of the same embodiment, FIG. 4 is a schematic configuration diagram of an inner cam type distribution fuel injection pump according to another embodiment, and FIG. 5 is a modification of the pressure control valve. A sectional view showing an example, FIG. 6 is a sectional view of a main part of a distribution type fuel injection pump for explaining the prior art. ■ ... Foot pump IA ... Fuel filter 2 ... Tank 3 ... - Pressure regulating valve 6 ... Cylinder 7 ... Rotor 8
... Plunger 9 ... Plunger chamber 12 ... Shoe 13 ... Roller 14 ... Inner cam 19 ... Electromagnetic spill valve 22 ... ECU 26 ... Timer piston 32 ... Cam chamber 34 to 36... Annular groove (passage) for fuel recovery 45... Annular groove 49... Lubricating oil passage 50.50A... Pressure control valve 64...
Oil pan agent Patent attorney Tsutomu Sadatsu (and 1 other person) Figure 2 44 25. 392σ Figure 3 Figure 5, (1) Figure 6

Claims (1)

[Scope of Claims] 1. An inner cam having an inner periphery as a cam surface, and a rotor disposed inside the inner cam and rotating relative to the inner cam by rotation of a drive shaft, the radial direction of the rotor The end faces of at least two plungers that slide oil-tightly in the fitting holes drilled in the cam surface are moved along the cam profile formed on the cam surface to cause the plungers to reciprocate and open the plunger chamber. In a distribution type fuel injection pump that pumps fuel from the plunger chamber, the inner cam and its surroundings are lubricated in an oil-tight state with lubricating oil other than fuel in the cam chamber, and are routed through a route different from the fuel route pumped from the plunger chamber. A fuel recovery passage is provided to recover fuel leaked from the sliding parts of the plunger chamber and its peripheral devices, and the fuel recovery passage or the passage communicating with the cam chamber is provided with a fuel recovery passage that is connected to the plunger chamber and the cam chamber so that the hydraulic pressure in both passages is equalized or the fuel is A distribution type fuel injection pump characterized by being equipped with a pressure control valve that slightly increases the fuel pressure in the recovery passage. 2. Claims characterized in that the pressure control valve is a spool valve that is provided in a passage connecting the fuel recovery passage and a passage communicating with the cam chamber and equalizes the hydraulic pressure between both passages. The distribution type fuel injection pump according to item 1. 3. The distribution type fuel injection pump according to claim 1, wherein the pressure control valve is a check valve that is provided in the fuel recovery passage and only allows fuel to flow toward a low pressure side.