JP2513256B2 - Distributed fuel injection pump - Google Patents

Description

The present invention relates to an inner cam type distribution type fuel injection pump,
More specifically, the present invention relates to a distributed fuel injection pump that lubricates a cam chamber formed by an inner cam and a rotor with a lubricating oil other than fuel.

[Prior Art] Conventionally, the injection pressure of a fuel injection pump has been improved as the social demand for fuel economy has increased, and in a distributed fuel injection pump for a diesel engine, a conventional face cam type has been used. Instead of the above structure, a so-called inner cam type in which the inner circumferential surface is used as a cam surface has been proposed (for example, Japanese Patent Laid-Open No. 61-96168). In such an inner cam type distribution type fuel injection pump, a plunger provided slidably in a fitting hole formed in a radial direction of a rotor is driven by a cam profile of an inner cam, and fuel is injected by the compression of fuel by the plunger. I do.

Such an inner cam type distribution type fuel injection pump is advantageous in increasing the injection pressure because it is possible to provide a plurality of plungers for pumping the fuel.

[Problems to be Solved by the Invention] However, the kerosene / alcohol mixed fuel, which has been recently considered to be used as a fuel for a diesel engine in addition to light oil, requires a fuel injection pump to have a higher pressure. However, it causes durability problems.

That is, the higher pressure of the injected fuel increases the contact pressure between the inner cam and the plunger that moves along the cam profile, and the inner cam, the roller slidingly contacting the inner cam, the shoe that rotatably holds the roller, and the like. Increase load stress. Conventionally, the lubrication of the cam chamber that houses these members has been done with fuel oil, but under such high load use, the lubrication becomes insufficient, and the wear of the members progresses and the deterioration of pump characteristics and durability. Invite problems such as decline.

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

However, in the fuel injection pump of the type in which the cam chamber is lubricated with a lubricating oil other than fuel in this way, there arises a problem that the lubricating oil leaks from the sliding portion provided between the two chambers and mixes with the fuel. ing. For example, a sectional view of the rotor of the fuel injection pump, the timer and its peripheral portion shown in FIG. 6 will be described. A rotor 103, which is rotationally driven by the engine, is provided on the inner peripheral side of the inner cam 101. Plunger 107 is fitted in fitting hole 105 of 103,
By moving the roller 111 housed in the shoe 109 along the cam face 101a of the inner cam 101, the plunger 107 is reciprocally moved in the radial direction, and the fuel in the plunger chamber 113 is pressure-fed.
A timer 120 is provided as a mechanism for changing the injection timing by moving the inner cam 101 in the rotation direction. This timer 120 is provided with pressure chambers 123 and 125 formed on both sides of a timer piston 121, and the timer piston 121 is moved by the balance of the hydraulic pressure of these chambers and the force of a spring 127 to move the inner cam via a piston pin 129. It is for rotating 101. However, in this device, the outer peripheral sliding surface of the piston pin 129 and the timer piston 1 are separated from the cam chamber 131.
Lubricating oil leaks through the outer peripheral sliding surface of 21. The leaked lubricating oil easily mixes into the fuel recovery passage 133 for recovering the fuel leaked from the pressure chamber 123 or the like. Therefore, there is a problem that the fuel filter (not shown) communicating with the fuel recovery passage 133 is clogged.

A face cam type fuel injection pump provided with a pressure mechanism in which a plunger chamber and a cam chamber are separated is known, for example, from Japanese Utility Model Publication No. 61-43952. Since both chambers are separated by a seal member, many seal members are required to obtain a sufficient sealing action, and the structure becomes complicated, and smooth operation is impeded by the movement of the sliding portion. was there.

The present invention has been made to solve the above-mentioned problems of the conventional technique, and prevents the lubricating oil in the cam chamber from mixing into the fuel through the fuel recovery passage, thereby eliminating clogging of the fuel filter. An object is to provide an inner cam type distribution type fuel injection pump.

[Means for Solving Problems] A distribution type fuel injection pump of the present invention includes an inner cam having an inner peripheral surface as a cam surface, and a relative rotation with respect to the inner cam due to rotation of a drive shaft arranged inside the inner cam. A rotor that rotates in a radial direction, and the end faces of at least two plungers that slide oil-tightly in a fitting hole that is opened in the radial direction of the rotor are formed along a cam profile formed on the cam surface. In the distribution type fuel injection pump that reciprocates the plunger by moving the plunger to move the fuel from the plunger chamber, the inner cam and its peripheral portion are lubricated in an oiltight state by the lubricating oil other than the fuel in the cam chamber. A fuel recovery passage for recovering fuel leaked from the sliding portion of the plunger chamber and its peripheral device is provided in a route different from the fuel route pumped from The fuel return passage or passages communicating with the cam chamber, is characterized in that equal fluid pressure in both passages, or the pressure control valve to slightly higher fuel pressure in the fuel return passage is provided.

[Operation] 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 with this rotation, the plunger radiates in the fitting hole along the cam profile of the inner cam. The fuel is pumped by sliding in the direction. Moreover, in the distributed fuel injection pump of the present invention, the lubrication mechanism lubricates the cam chamber including the inner cam and the rotor with the lubricating oil other than the fuel. Therefore, the lubrication between the inner cam and the rotor of the distributed fuel injection pump whose pressure is increased can be sufficiently ensured by the lubricating oil other than the fuel, for example, the lubricating oil having a viscosity higher than that of the fuel.

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

Further, since this pump is provided with a pressure control valve between the fuel recovery passage and the passage communicating with the cam chamber, whether the liquid pressure inside the fuel recovery passage and the cam chamber is equal or the pressure in the fuel recovery passage is Will be higher. Therefore, the lubricating oil will not leak into the fuel recovery passage from the sliding portion between the cam chamber and the fuel recovery passage, and the lubricating oil will not be mixed with the fuel.

[Embodiment] In order to further clarify the configuration and operation of the present invention described above, a preferred embodiment of the inner cam type 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 the line AA of FIG.

As shown in the figure, the inner cam type distribution type fuel injection pump provided with the feed pump 1 is of the electromagnetic spill metering type. Its composition along the flow of fuel,
A brief description will be given below.

The feed pump 1 includes a tank 2 and a fuel filter A,
And fuel pump 1B that supplements the fuel pressure loss of fuel filter 1A
The fuel is pumped up via the, and the pumped fuel is regulated by the pressure regulating valve 3 and supplied to the gallery 5 in the head 4. Fuel in gallery 5 is cylinder 6
The plunger 8 through the passage 6a in the rotor 7 and the passage 7a in the rotor 7.
Is introduced into the plunger chamber 9 formed by. The rotor 7 is slidably fitted to the cylinder 6,
It is held by the bearing 10 and rotationally driven by the engine.

Further, a plurality of fitting holes 7A are formed in the outer circumference of the rotor 7 in the radial direction of the rotor 7, and inside the cylindrical hole 7A,
The plunger 8 is slidably fitted. A shoe 12 is arranged at the radially outer end of the plunger 8 so as to rotatably hold a roller 13. On the outside of the rotor 7,
An inner cam 14 having a cam mountain formed on the inner surface is arranged. Since the plunger 8 is biased in the outer peripheral direction by the pressure of the fuel, the roller 13 at the end of the plunger 8 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 surface of the inner cam 14 by the rotation of the rotor 7, the roller 13 reciprocates in the radial direction based on the cam surface, and the movement of the roller 13 It is transmitted to the plunger 8 through 12. Here, the stroke of the plunger 8 toward the outside in the radial direction of the rotor 7 is the intake stroke, and the stroke toward the inside is the discharge stroke.

The passage 6a in the cylinder 6 and the passage 7a in the rotor 7 described above.
With respect to the positional relationship in the circumferential direction, the two passages communicate with each other in the fuel intake stroke caused by the movement of the plunger 8 in the inner circumferential direction due to the rotation of the rotor 7, and are closed in the compression stroke. Further, the rotor 7 is provided with a spill port 15 and a discharge port 16 communicating with the plunger chamber 9, and the passages 17, 18 provided in the cylinder 6 during the discharge stroke.
And communicate with each. An electromagnetic spill valve 19 is arranged at the end of the passage 17 to connect and disconnect the passage 17 and the gallery 5. The electromagnetic spill valve 19 is a signal indicating the operating state of the engine,
For example, it is driven by the ECU 22 based on a signal from the accelerator opening sensor 20, a signal from the rotation angle sensor 21, and the like.
The passage 18 in the cylinder 6 communicates with the delivery valve 24 via the passage 23 in the head 4 and a pipe for communicating with the nozzle mounted on the engine.

With the above configuration, the rotor 7 is rotated by the rotation of the engine.
When is rotated, the plunger 8 repeats the suction stroke for sucking the fuel through the gallery 5 and the compression stroke for sending the fuel to the fuel injection valve through the delivery valve 24, and the electromagnetic spill valve 19 synchronizes with this. The overflow timing is adjusted, that is, the fuel injection amount is controlled.

The second adjustment of fuel injection timing is done in this way.
It is performed by a timer as shown in the figure. That is, the inner cam 14 is connected to the timer piston 26 via the slide pin 25, and the timer cam 26 moves to rotate / displace the inner cam 14. That is, the timer has a pressure chamber 27 on one end surface of the timer piston 26.
Is formed, and the pressure chamber 27 and the gallery 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 for urging the timer piston 26 toward the pressure chamber 27 is arranged. Further, the low pressure chamber 29 is connected to the inner cam 14 by the communication hole 31 provided in the timer piston 26.
Communicates with the cam chamber 32 in which is stored.

Therefore, the position of the timer piston 26 is controlled by the balance between the force received by the timer piston 26 due to the pressure inside the pressure chamber 27 and the force received by the timer piston 26 due to the pressure inside the low pressure chamber 29 and the biasing force of the spring 30. Timer pressure chamber
27 communicates with the gallery 5, and the fuel whose pressure is adjusted by the pressure adjusting valve 3 is introduced. Since the pressure control valve 3 generates a high pressure as the rotation speed increases, the timer piston 26 is displaced to the low pressure chamber 29 side as the rotation speed increases.

Next, a mechanism related to the means for collecting the fuel leaking from the plunger chamber 9 and the timer and the mechanism related to the lubrication in the cam chamber 32, and a mechanism for preventing the mixing of the fuel and the lubricating oil as a characteristic configuration of the present embodiment will be described. To do.

An annular groove 34 that functions as a leak fuel recovery groove is formed on the sliding surface of each plunger 8. Further, an annular groove 35 that also functions as a leak fuel recovery groove is formed on the sliding surface of the cylinder 6 on which the rotor 7 slides.
Furthermore, the sliding surface of the timer piston 26 also on the pressure chamber 27 side,
An annular groove 36 that functions similarly as a leak fuel recovery groove is formed. The annular groove 34 for collecting these leaked fuel,
35 and 36 are connected to the fuel intake side of the feed pump 1, that is, the low pressure side, through the fuel passages 37, 38, 39 and 40.
Therefore, such an annular groove 34 for leak fuel recovery,
When the fuel is injected, the plunger 8 and the rotor 7 are made by 35 and 36.
Even if a part of the fuel leaks through the minute gap between them and the outer peripheral portion of the timer piston 26, they can be recovered and returned to the fuel tank 2.

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

A lubricating oil outlet 43out is provided in the lower portion of the cam chamber 32 in the figure, and the lubricating oil flowing from the lubricating oil inlet 43in through the throttle 41 lubricates the inner cam 14, the roller 13, and the shoe 12 and cools them. After removing the frictional heat, the lubricating oil outlet 43
From out, it flows into the lubricating system of the engine (not shown).

Further, as a characteristic configuration of the present embodiment, a pressure control valve 50 is provided in the fuel passage 40 and the lubricating oil passage 49 to which the lubricating oil outlet 43out is connected as a mechanism for preventing the lubricating oil from mixing with the fuel. It is connected. As shown in FIG. 3 in an enlarged manner, the pressure control valve 50 has a spool 53 slidably fitted in a valve body 51, and liquid chambers 55 and 57 are provided on both sides of the spool 53, respectively. Are formed. And one liquid chamber
55 has a fuel port 59 connected to the fuel passage 40, and the other liquid chamber 57 has a lubricating oil port 61 connected to the lubricating oil passage 49. A fuel discharge port 63 connected to the tank 2 through the passage 40a is provided on the side of the valve body 51, and an oil pan 6 is provided through the passage 49a.
Lubricating oil discharge ports 65 connected to 4 are respectively formed.

Next, the operation of the pressure control valve 50 will be described.
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,
The fuel discharge port 59 and the lubricating oil discharge port 65 are closed by the side surface of the spool 53. As a result, the cam chamber 32 and the fuel passage 40 are shut off from the atmosphere side.

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 spool 53 of the pressure control valve 50 moves upward in the drawing, and the lubricating oil passage 49 and the lubricating oil discharge Connect the port 65 to the oil pan 64 and connect the passage 49a.
Communicate through. As a result, the lubricating oil is collected in the oil pan 64, and the hydraulic pressure in the cam chamber 32 drops. Therefore, the liquid chamber
The liquid pressure in the liquid chamber 55 becomes higher than that in 57, and the spool 53 moves downward in the drawing. Then, the operation of the spool 53 is stopped when the liquid pressures of the liquid chamber 55 and the liquid chamber 57 become equal. Therefore, the lubrication hydraulic pressure of the cam chamber 32 becomes equal to the hydraulic pressure on the fuel passage 40 side. Therefore, the hydraulic pressures of the cam chamber 32 and the annular groove 36 as the fuel recovery groove are equalized via both the liquid chambers 55 and 57, so that the piston pin 25 and the housing 44 from the cam chamber 32.
The lubricating oil will not leak to the annular groove 36 through the gap between the and. Therefore, since the lubricating oil is not mixed with the fuel, the fuel filter 1A is not clogged with the lubricating oil mixed with the fuel.

Next, another embodiment will be described with reference to FIG.
A check valve 70 is provided in the fuel passage 40A for collecting fuel, and the fuel flowing out from the check valve 70 is returned to the tank 2. On the other hand, the fuel passage 49A for discharging the lubricating oil from the cam chamber 32 is directly connected to the oil pan 64. Therefore, since the fuel passage 40A and the passage 49A are both open to the atmosphere, the pressures at the outlets are almost the same, but the check valve 70 is provided only on the passage 40A. Due to the force of the spring of the stop valve 70, the fuel pressure in the recovery passage such as the annular groove becomes higher than the lubricating oil pressure in the cam chamber 32. Therefore, it is possible to prevent the mixing of the lubricating oil with the fuel as in the above-described embodiment.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments and may be modified as follows.

Instead of the pressure control valve 50 of FIG. 3, springs 80 and 82 having the same spring force are provided in the liquid chambers 55A and 57A of the pressure control valve 50A to stabilize the movement of the spool 53, as shown in FIG. Good.

The same function as the check valve shown in FIG. 4 is obtained by using only the spring of the other liquid chamber instead of the spring of the liquid chamber on the side communicating with the fuel passage of the pressure control valve 50A of FIG. May be configured to fulfill.

Further, the pressure check area on the side of the pressure control valve that communicates with the fuel passage of the spool may be made smaller than the other side so that the same check valve function as described above may be achieved.

[Effects of the Invention] As described in detail above, according to the inner cam type distribution type fuel injection pump of the present invention, it is possible to prevent the lubricating oil in the cam chamber from mixing into the fuel through the fuel recovery passage, and thus the fuel filter. The clogging of can be eliminated.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an inner cam type distribution type fuel injection pump as one embodiment of the present invention, and FIG. 2 is its A-A.
Sectional view, FIG. 3 is a sectional view showing the pressure control valve of the embodiment,
FIG. 4 is a schematic configuration diagram of an inner cam type distribution type fuel injection pump according to another embodiment, FIG. 5 is a sectional view showing a modified example of the pressure control valve, and FIG. 6 is a distribution type fuel for explaining the prior art. It is sectional drawing of the principal part of an injection pump. 1 …… Feed pump 1A …… Fuel filter 2 …… Tank 3 …… Pressure adjusting 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 or 36 …… annular groove (passage) for fuel recovery 45 …… annular groove 49 …… lubricating oil passage 50, 50A …… Pressure control valve 64 …… Oil pan

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Yukinori Miyata, 1-1, Showa-cho, Kariya city, Aichi Nihon Denso Co., Ltd. (56) References: 61-140171 (JP, U) 43952 (JP, U) Actually opened 55-176479 (JP, U)

Claims (3)

(57) [Claims] 1. An inner cam having an inner circumference 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 rotor is opened in a radial direction of the rotor. The end faces of at least two plungers that slide oil-tightly in the fitted holes are moved along the cam profile formed on the cam face to reciprocate the plungers and move the fuel from the plunger chamber. In the distribution type fuel injection pump that pressure-feeds, the inner cam and its peripheral portion are lubricated in an oil-tight state by a lubricating oil other than the fuel in the cam chamber, and in a route different from the fuel route pressure-fed from the plunger chamber,
A fuel recovery passage is provided for recovering fuel leaking from the sliding portion of the plunger chamber and its peripheral devices. The fuel recovery passage or the passage communicating with the cam chamber has equal fluid pressures in both passages or the fuel recovery passage. A distributed fuel injection pump, characterized in that a pressure control valve for slightly increasing the fuel pressure in the passage is provided. 2. The pressure control valve is a spool valve for equalizing the fluid pressure between both passages provided in a passage connecting the fuel recovery passage and a passage communicating with the cam chamber. The distributed fuel injection pump according to claim 1. 3. The distribution type according to claim 1, wherein the pressure control valve is a check valve which is provided in the fuel recovery passage and allows only the flow toward the low pressure side of the fuel. Fuel injection pump.