JP2661466B2 - Anti-vibration device for fuel injection pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration preventing device for a fuel injection pump provided in a diesel engine.

[0002]

2. Description of the Related Art As shown in FIG.
The fuel sent by the feed pump 2 is pressurized by a plunger (not shown), and is injected from the discharge port 3 to each cylinder of the engine via an injection steel pipe 4 and an injection nozzle (not shown). In addition, a governor 6 for controlling the injection amount is provided.

A driving shaft 8 supported by a bearing box 7 transmits rotation from a driving gear 9 to a cam shaft 5 for driving the plunger, and a coupling 10 is provided between the driving shaft 8 and the driving shaft 8. ing. In recent years, in order to respond to strict demands for exhaust gas improvement, a variable prestroke type fuel injection pump has become the mainstream in place of injection control using a timer, and the conventional timer position has a shaft torque. A flywheel 11 for averaging and smoothing the rotation is attached.

[0004]

By the way, in such a drive system of the fuel injection pump, the flywheel 11 or the timer is used as an inertia mass using the drive torque that fluctuates periodically as a vibration source, and the drive gear 9 and the drive gear are used. A torsional vibration is generated using the shaft 8 and the coupling 10 as torsion springs. Due to this vibration, as shown in FIG. 6, as the frequency approaches the natural frequency of the drive system, torsional resonance (appearing as a drive torque peak in the figure) occurs in which the amplitude sharply increases. In addition, excessive torque was generated, and it was a large noise source. In recent years, high-pressure injection has been promoted in order to comply with exhaust gas regulations, and driving torque has been increased, so that resonance countermeasures have become very important. FIG. 6 also shows the torque of a drive system provided with a timer. However, since the timer has a built-in spring and flyweight, the magnitude of the drive torque is reduced, but the resonance cannot be suppressed. Similarly, a large torque peak occurs.

As a countermeasure against resonance, the flywheel 11
It is also conceivable to make the mass significantly smaller and raise the natural frequency so that the resonance speed is outside the normal rotation range. However, even with such a configuration, large resonance occurs as shown in FIG. The resonance frequency of a flywheel with a small mass is smaller than that of a large flywheel with fourth, fifth, and sixth orders of injection, while the excitation force is usually smaller at sixth, seventh, and eighth orders. On the higher side,
As shown in the torque waveform diagram of FIG. 7, the vibration torque generated on the camshaft of the injection pump is extremely shocking, so that the vibration order is very high.

FIG. 7 also shows a torque waveform of a camshaft having a small inertia mass, but the torque fluctuation is larger than that of a camshaft having a large mass. For this reason, there arises a problem that the noise accompanying the driving of the injection pump is deteriorated and that the stability and the durability of the governor 5 are also affected.

In addition to the above, there is a rubber damper used for an engine crankshaft to suppress resonance.
The basic principle of this damper is to reduce the natural frequency of the crankshaft by applying a mass called the damper to reduce the natural frequency by dividing the natural frequency into two parts. This is intended to lower the rotation range to a low excitation force. Therefore, even if this type of damper is employed in the drive system of the injection pump, it resonates with a higher-order excitation force, and the purpose cannot be achieved.

Therefore, the present invention is based on the situation that the drive system of the injection pump requires a sufficiently large flywheel, and the driving force of the injection pump has a large high-order vibration component and cannot be handled by a rubber damper. The present invention has been devised to provide a vibration preventing device for a fuel injection pump that suppresses harmful vibration by suppressing resonance of a drive system.

[0009]

According to the present invention, a rotary member having a flywheel function is provided on a cam shaft of a fuel injection pump, and the rotary member is connected to a drive shaft via a coupling.
In addition, an annular mass body is fitted to the rotating member so as to be slidable in the circumferential direction with a predetermined gap , and the gap is filled with a highly viscous fluid.

[0010] The rotating member may be a case of a timer attached to a camshaft.

[0011]

According to the above construction, the rotating member averages the torque of the camshaft, and absorbs the relative displacement between the rotating member and the annular mass with a highly viscous fluid to attenuate the torsional vibration.

[0012]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows a first embodiment of an apparatus for preventing vibration of a fuel injection pump according to the present invention. In this vibration preventing device, a rotary member 21 having a flywheel function is provided on a cam shaft 5 of a fuel injection pump 1, and an annular mass body which is slidably fitted in a circumferential direction with a predetermined gap to the rotary member 21. 22 are provided, and the gap is filled with silicon oil 23 as a highly viscous fluid.

The fuel injection pump 1 has a pre-stroke function that does not require a timer, and performs high-pressure fuel injection by transmitting a rotational driving force to the camshaft 5. The rotating member 21 is formed of a short cylinder having a sufficiently large mass, and the end of the cam shaft 5 penetrates a concave portion 24 formed at the center of the shaft and is fastened by a nut 25.
The coupling 10 connected to the drive shaft 8 is connected to the opposite end face by a bolt 26.

An annular chamber 27 having a substantially square cross section is formed coaxially inside the rotating member 21, and an annular mass body 22 having substantially the same shape as the annular chamber 27 is interposed in the annular chamber 27 via a silicone oil 23. Housed. Therefore, the annular mass body 22 functions as inertia.

In addition, a drive gear 9 is attached to the drive shaft 8 as in the prior art, and is rotatably supported by the bearing housing 7.

Next, the operation of this embodiment will be described.

The fuel injection pump 1 performs fuel injection by rotating the camshaft 5 by the rotational driving force transmitted from the drive shaft 8 and vertically moving a plunger (not shown) engaged with the camshaft 5. At this time, the shaft torque is
It is made uniform by one flywheel function. Then, in the drive system, a torsional vibration is generated in which the drive torque is used as a vibration source and the rotating member 21 is used as an inertial mass. The relative displacement in the circumferential direction between the rotating member 21 and the annular mass body 22 is caused by the silicone oil 23. It is quickly absorbed and attenuated by the viscosity (shear resistance) of the material.

As described above, the annular mass 2 is attached to the rotating member 21 serving as a flywheel via the silicon oil 23.
2 and the viscous damper, the torque fluctuation of the camshaft 5 is suppressed, harmful torsional vibration is attenuated, and the occurrence of resonance is prevented. Especially viscous
The mounting position of the damper to a place where the amplitude of torsional vibration is large.
Between the camshaft 5 and the coupling 10,
Very effectively damping of the vibrations is achieved.

FIG. 2 shows the results of measurement of the driving torque in the above embodiment performed by the present inventors. FIG. 3 also shows the torque of the camshaft and the torque of a drive system having a conventional mass-sized flywheel for comparison. Also in FIG.
3 shows torque waveforms of a drive shaft and a camshaft of the embodiment. As is evident from these measurement results, in the present invention, while the torque fluctuation of the camshaft is suppressed small,
It can be seen that the drive torque of the drive system does not show a peak due to only a gradual change, and the resonance is almost completely eliminated. That is, the effect of the present invention was demonstrated.

Next, a second embodiment of the present invention will be described with reference to FIG.

This embodiment shows a case where a timer case 32 attached to a cam shaft 5 is used as a rotating member in a configuration in which a timer 31 is provided in a fuel injection pump. The timer 31 includes a disc-shaped case 34 connected to the camshaft 5 via a holder 33 as a case 32 serving as an outer shell, and a drive shaft-side case 35 having a bottomed cylindrical shape. Disc-shaped case 3
3 are fitted slidably in the circumferential direction at the edge. The holder 33 includes a cylindrical portion 3 fitted to an end of the camshaft 5.
6 and a disk portion 37 formed at one end thereof.
A weight 38 divided into two parts with a spring (not shown) is fitted around the outer circumference of the disk 6, and a large cam 39 and a small cam 40 which are appropriately eccentric are provided in the disk 37. I have. The small cam 40 and the drive shaft side case 35 are connected by a pin 41 extending in the axial direction, and the large cam 39 and the weight 38 are connected by another pin 42. That is, when the rotation speed increases and the weight 38 moves radially outward against the spring due to the centrifugal force, the large cam 39 and the small cam 40 rotate around the pin 41, so that the holder 37 moves around the axis. By rotating, the camshaft 5 side is advanced with respect to the drive shaft 8.

The case 32 of the timer 31 is formed with a predetermined mass so as to play the role of a flywheel. In this embodiment, an annular chamber 43 is formed inside the disc-shaped case 34. In the same manner as in the first embodiment, an annular mass body 44 as an inertia ring is fitted, and the gap is filled with silicone oil 45.
Therefore, torque fluctuation is suppressed by the disc-shaped case 34,
The generation of torsional vibration is prevented by the vibration damping action of the silicon oil 45, and the resonance is eliminated.

In this embodiment, as shown by a two-dot chain line in the figure, the annular mass 51 may be provided on the drive shaft side case.

[0025]

In summary, according to the present invention, the following excellent effects are exhibited.

A rotary member having a flywheel function is provided on the camshaft, and the rotary member is driven via a coupling.
While connected to the rotary shaft, and an annular mass body which fits with a predetermined gap, so was filled with highly viscous fluid in the gap, and an annular mass body torque varying fitting, high viscosity in the gap Since the fluid is filled, torque fluctuations are suppressed, and harmful torsional vibrations are quickly attenuated, thereby suppressing the occurrence of resonance.

[Brief description of the drawings]

FIG. 1 is a sectional side view showing a main part of a first embodiment of a vibration preventing device for a fuel injection pump according to the present invention.

FIG. 2 is a drive torque change diagram for explaining the operation and effect of FIG. 1;

FIG. 3 is a torque waveform chart for explaining the operation and effect of FIG. 1;

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

FIG. 5 is a side view showing a conventional fuel injection pump.

FIG. 6 is a diagram showing a change in driving torque for explaining a problem of the related art.

FIG. 7 is a torque waveform diagram for explaining a problem of the related art.

[Explanation of symbols]

 Reference Signs List 1 fuel injection pump 5 camshaft 21 rotating member 22 annular mass body 23 silicon oil (high-viscosity fluid)

Claims (2)

(57) [Claims] 1. A rotary member having a flywheel function is provided on a cam shaft of a fuel injection pump, and the rotary member is coupled to the rotary shaft.
While connected to the drive shaft via the ring, and characterized in that the annular mass body slidably fitted in the circumferential direction with a predetermined clearance to the rotary member is provided and is filled with highly viscous fluid in the gap Vibration prevention device for fuel injection pump. 2. The vibration preventing device for a fuel injection pump according to claim 1, wherein the rotating member is a case of a timer attached to the camshaft.