JPH0322549Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a fuel injection pump used in a diesel engine, particularly one having a variable injection timing mechanism.

(Prior art) As this type of fuel injection pump, for example,
As shown in Japanese Patent No. 57-142167, it is known that a control sleeve is slidably fitted onto a plunger within a pump body, and the injection timing is adjusted by moving the control sleeve in the axial direction. Additionally, in this publication, a pin insertion hole is formed in the pump body, an eccentric pin is rotatably inserted into the pin insertion hole, and the eccentric pin is connected to a control sleeve to move the control sleeve. It is shown. Between the above eccentric pin and the pump body,
A sealing member made of an O-ring is interposed to seal the pump body so that the fuel does not leak to the outside.

(Problem to be solved by the invention) However, in the above conventional example, the eccentric pin is inserted directly into the pump body, so it is necessary to increase the crushing margin of the seal member to withstand the hydraulic pressure inside the pump body. The problem was that friction between the eccentric pin and the pump body increased and a large driving force was required to move the control sleeve.

Therefore, the object of this invention is to provide a fuel injection pump that can drive the control sleeve with a small force by reducing the friction of the eccentric pin, thereby improving controllability.

(Means for Solving the Problems) Therefore, the gist of this invention is to slidably fit a control sleeve on the plunger within the pump body, and to insert the control sleeve into the pump body. In the fuel injection pump, the eccentric pin is connected to an eccentric pin and moves the control sleeve in the axial direction via the eccentric pin to adjust the injection timing. comprising a flange portion and an engaging portion formed eccentrically on the flange portion and engaged with the control sleeve, and a bushing is provided around the shaft portion of the eccentric pin so as to abut the flange portion; A first sealing member is interposed between the bushing and the pump body, and a second sealing member is interposed between the bushing and the eccentric pin.

(Function) Therefore, the eccentric pin uses the inner diameter of the bush as a guide and rotates around its shaft as a fulcrum to transmit driving force to the control sleeve. The working circumference that receives the contact resistance of the eccentric pin can be reduced, and the first seal member is used to seal between the pump body and the bushing, and the contact part of the flange part and the bushing are sealed between the bush and the eccentric pin. Since the second seal member is used for sealing, even if the crushing margin of the second seal member is small, it can withstand the internal fuel pressure, and therefore the above object can be achieved.

(Example) In Fig. 2, the fuel injection pump is of a type that is directly attached to the main body of a diesel engine, and the pump main body 1 is formed with vertical holes 2 corresponding to the number of cylinders. A plunger barrel 3 is fixed. The plunger barrel 3 is composed of an outer barrel 3a, an upper barrel 3b fitted into the upper part of the outer barrel 3a, and a lower barrel 3c fitted into the lower part of the outer barrel 3a. A valve holder 4 is screwed to the upper end, and the upper barrel 3b and the valve seat body 5 are tightened by this valve holder 4. A delivery valve 6 is seated on the valve seat body 5, and a fuel outlet 7 is formed at the upper end of the valve holder 4.

The upper end of the plunger 8 is fitted into the above-mentioned upper barrel 3b, and forms a high pressure chamber 9 between the plunger 8 and the upper barrel 3b. Moreover, the middle part of this plunger 8 is the lower barrel 3 mentioned above.
It is inserted into c. Further, the lower end of this plunger 8 is engaged with a lower spring receiver 10. The lower spring receiver 10 is in contact with a tapepet 12 having a roller 11 with a shim 13 interposed therebetween, and a return spring 15 is elastically loaded between the lower receiver 10 and the upper spring receiver 14. 15 applies a returning force to the plunger 8. Furthermore, a face portion 16 is formed on the plunger 8, and this face portion 16 engages with an injection amount control pinion 17 fitted externally on the lower barrel 3c.
An injection amount control rack 18 is engaged with the
By moving the rack 18, the pinion 1
The plunger 8 is rotatable via the shaft 7.

The center portion of the plunger barrel 3 described above is cut out to form a fuel reservoir chamber 19. This fuel reservoir chamber 19 communicates with a fuel inlet 20 formed in the pump body 1, and the fuel reservoir chamber 19 is in communication with a fuel inlet 20 formed in the pump body 1.
A control sleeve 21 is arranged at 9 and is slidably fitted onto the plunger 8 .

This control sleeve 21 is
A groove 22 is formed in the longitudinal direction of the circumference, and a locking pin 23 fixed to the plunger barrel 3 is inserted into this groove 22.
are engaged to prevent rotation of the control sleeve 21. In addition, this control sleeve 21
A cut-off hole 24 is formed in the radial direction. A lead 25 is obliquely formed on the outer periphery of the plunger 8 described above in correspondence with the cut-off hole 24 . This lead 25 communicates with the aforementioned high pressure chamber 9 via horizontal holes 26a, 26b formed in the plunger 8 and a communication hole 27. Further, an annular groove 28 is formed on the periphery of the control sleeve 21.
An engaging portion 34 of an eccentric pin 31 (described later) engages with this annular groove 28, and is further connected to a timing control rod 29 via this eccentric pin 31. This timing control rod 29 is connected to the presser plate 30.
It can be moved in the lateral direction of the pump body 1 by being held down by the pump body 1.

As shown in detail in FIG.
1 includes a cylindrical shaft portion 32, a flange portion 33 formed at one end of this shaft portion 32, and an engaging portion 34 formed eccentrically on this flange portion 33. engages the annular groove 28 of the control sleeve 21 as described above. This eccentric pin 3
1 is provided with a disk 35 at the other end, and this disk 35
A coupling hole 36 is formed in the center of the disc 35, and a caulking portion 37 formed on the eccentric pin 31 is fitted into the coupling hole 36, and the caulking portion is inserted using, for example, a tapered tool 46. It is fixed by caulking 37. Further, a ball 38 is fixed near the peripheral edge of the disc 35 by, for example, brazing, and this ball 38 engages with an engagement groove 39 formed in the timing control rod 29 described above.

The inner surface of the bush 40 is fitted onto the shaft portion 32 of the eccentric pin 31, and one end of the bush 40 is in contact with the inner surface of the flange portion 33 of the eccentric pin 31. A first seal member fitting groove 41 is formed along the circumferential direction on the outer peripheral surface of this bushing 40, and a first seal member fitting groove 41 made of an O-ring is formed in the fitting groove 41.
A seal member 42 is fitted therein. With the first seal member 42 compressed, the bush 40 is inserted so as to be fixed in the pin insertion hole 43 formed in the pump body 1, and the first seal member 42 is inserted between the pump body 1 and the bush 40. mediated by.

The second seal member 44 is made of, for example, an O-ring coated with a Teflon coating material, and is interposed between the shaft portion 32 of the eccentric pin 31 and the bush 40. That is, a second seal member fitting groove 45 is formed along the circumferential direction on the outer periphery of the shaft portion 32 of the eccentric pin 31, and the second seal member 44 is fitted into the fitting groove 45, and the bush 40 By inserting the second seal member 44 into the eccentric pin 31, the outer peripheral surface of the second seal member 44 is brought into contact with the inner peripheral surface of the bush 40. This second
The sealing member 44 can provide a certain degree of sealing between the abutment surfaces of the flange portion 32 and the bushing 40;
The degree of compression is smaller than that of the second seal member 44, and together with the fact that it is coated with Teflon, the friction caused by the second seal member 44 is reduced.

After the eccentric pin 31, disc 35, ball 38, bush 40, first seal member 42, and second seal member 44 are assembled as shown in FIG. It is inserted into the hole 43.

In the above configuration, when the roller 11 is received upward from the cam (not shown) in the state shown in FIG.
Plunger 8 begins to rise against return spring 15. However, at the beginning of the rise, plunger 8
The horizontal hole 26b of the plunger 8 opens into the fuel reservoir chamber 19, and the fuel reservoir chamber 19 and the high pressure chamber 9 communicate with each other via the horizontal hole 26b of the plunger 8 and the communication hole 27. The pressure does not increase and the delivery valve 6 remains closed and no fuel is pumped out.

When the plunger 8 further rises, the horizontal hole 26b of the plunger 8 is closed by the lower edge of the control sleeve 21, communication between the high pressure chamber 9 and the fuel reservoir chamber 19 is cut off, and the pressure of the fuel in the high pressure chamber 9 increases. The delivery valve 6 opens and sends out high pressure fuel from the fuel outlet 7. This time is the start of injection, and the stroke of the plunger 8 from the start of the rise of the plunger 8 to the start of this injection is the prestroke.

When the plunger 8 further rises, the lead 25 of the plunger 8 finally opens into the cut-off hole 24 of the control sleeve 21, and the high pressure chamber 9 and the fuel reservoir chamber 19 are connected to the communication hole 27 of the plunger 8 and the horizontal hole 26.
a, 26b and lead 25 and control sleeve 2
The fuel in the high pressure chamber 9 escapes to the fuel reservoir chamber 19 through these passages, the pressure of the fuel in the high pressure chamber 9 decreases, and the delivery valve 6 closes. This is the end of injection, and the stroke of the plunger 8 from the start of injection to the end of injection is the effective stroke.

The injection amount is adjusted by moving the injection amount control rack 18. This injection amount control rack 18
When the plunger 8 is moved, the plunger 8 rotates via the injection amount control pinion 17, the relative position of the plunger 8 and the control sleeve 21 in the circumferential direction changes, and when the lead 25 communicates with the cut-off hole 24, that is, the injection The effective stroke can be changed by changing the end time.

The injection timing is adjusted by moving the timing control rod 29. When the timing control rod 29 is moved, the engagement groove 39 of the timing control rod 29 engages with the ball 38, so the ball 38, the disc 35, and the eccentric pin 31 are integrated and the eccentric pin 31 is moved. It rotates around the shaft portion 32 as a fulcrum. Since the engaging portion 34 of the eccentric pin 31 is engaged with the annular groove 28 of the control sleeve 21, the control sleeve 21 moves up and down,
When the horizontal hole 26b of the plunger 8 is closed by the lower edge of the control sleeve 21, the timing of the start of injection changes, and the prestroke can be changed.

In adjusting this injection timing, the eccentric pin 31 uses the shaft portion 32 of the eccentric pin 31 as a fulcrum,
It rotates using the inner peripheral surface of the bush 40 as a guide.
In this case, the second seal member 44 of the eccentric pin 31
The circumference on which the frictional resistance acts is the inner circumferential surface of the second seal member fitting groove 45 (its diameter is φd). Conventionally, the eccentric pin 31 has a size that includes the bush 40, and the first part of the bush 40 is
The inner circumferential surface of the seal member fitting groove 41 was the circumference on which the frictional resistance acts (its diameter is φD).
Therefore, compared to the conventional case, the circumference on which frictional resistance acts is reduced from ΦD to Φd, and the frictional resistance caused by rotation of the eccentric pin 31 can be reduced. This is because the engaging portion 34 of the eccentric pin 31 maintains the movement stroke of the control sleeve 21 at a predetermined value.
However, in the past, the eccentric pin was directly inserted into the pump body 1, so the diameter of the pivot point of the eccentric pin was the outer diameter of the bush 40 in this embodiment. However, in this embodiment, the eccentric pin 31
A flange portion 33 is formed on the flange portion 33 .
Since the engaging portion 34 is formed at the center, the eccentricity of the engaging portion 34 can be maintained at a predetermined value even if the diameter of the rotational fulcrum portion is made small.

As described above, in this embodiment, the circumference of the eccentric pin 31 where the frictional resistance is applied is made small, the crushing margin of the second seal member 44 is made small,
The second seal member 44 is made of Teflon coating, thereby reducing the frictional resistance of the eccentric pin 31.

(Effects of the invention) As described above, according to this invention, in a fuel injection pump in which injection timing is controlled by moving a control sleeve fitted over the plunger, an eccentric pin for moving the control sleeve is provided. A bushing is provided between the shaft and the pump body, and the eccentric pin uses the inner circumferential surface of the bushing as a guide and rotates with the bushing abutting against the flange formed on the eccentric pin. While ensuring the oil-tightness of the pin insertion part, the circumference of the eccentric pin where the frictional resistance is applied is reduced, and the amount of crushing of the second seal member that seals between the eccentric pin and the bushing is reduced, resulting in a small drive. The eccentric pin can be rotated by force, and for example, when an actuator is used to move the eccentric pin, the driving force of the actuator can be reduced, thereby improving controllability.

[Brief explanation of the drawing]

Fig. 1 is a partially enlarged sectional view of Fig. 2 showing the peripheral part of an eccentric pin used in an embodiment of this invention;
The figure is a sectional view showing a fuel injection pump in the same embodiment. 1...Pump body, 8...Plunger, 21...
... Control sleeve, 31 ... Eccentric pin, 32 ... Shaft section, 33 ... Flange section, 34 ... Engagement section, 40
...Button, 42...First seal member, 44
...Second seal member.

Claims (1)

[Claims for Utility Model Registration] 1. A control sleeve is slidably fitted onto the plunger within the pump body, and this control sleeve is connected to an eccentric pin inserted into the pump body, and the control sleeve is connected to the eccentric pin inserted into the pump body, and the In a fuel injection pump that adjusts injection timing by moving a control sleeve in the axial direction, the eccentric pin is formed on a cylindrical shaft portion, a flange portion formed at one end of the shaft portion, and eccentrically formed on the flange portion. an engaging portion that engages with the control sleeve; a bushing is provided around the shaft portion of the eccentric pin so as to abut the flange portion; and a first portion is provided between the bushing and the pump body. A fuel injection pump characterized in that a seal member is interposed, and a second seal member is interposed between the bush and the eccentric pin. 2. Utility model registration claim 1, characterized in that the second sealing member is composed of an O-ring coated with a coating material having a small coefficient of friction.
Fuel injection pump as described in section.