JPH018669Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] This invention is a fuel injection timing for internal combustion engine in which the advance angle of the drive shaft of a fuel injection pump is adjusted using the displacement action of a timing weight based on centrifugal force. Relating to an adjustment device.

[Conventional technology]

Generally, in a diesel engine or the like, as the rotational speed of the engine increases, the fuel injection timing is advanced (advanced) and adjusted so that fuel injection is performed at the highest pressure point.

Various types of fuel injection timing adjustment devices (referred to as automatic timers) of this type are known, but the following mechanical means are typical. In other words, the rotation of the drive flange rotated by the engine is transmitted to the timing weight, and by utilizing the fact that this timing weight is expanded and displaced based on centrifugal force, this displacement is transmitted to the timing hub via a large eccentric cam and a small eccentric cam. By angularly displacing the timing hub relative to the drive flange, the drive shaft of the fuel injection pump connected to the timing hub is advanced and driven.

[The problem that the idea aims to solve]

By the way, in those using this type of timing weight, the engine vibration is large, especially in the low rotation range such as when starting the engine, so this vibration may cause axial vibration in the timing weight. be.

As a result, the timing weight repeatedly collides with the flanges, etc. located on both sides, causing Np-
As shown by D in dB characteristics (Np is pump rotation speed),
The collision noise became louder in the low engine speed range, and the engine used in the vehicle had a problem that caused discomfort to the passengers.

Additionally, such collisions also have the disadvantage of causing premature wear of related parts.

Furthermore, when the timing weight repeatedly collides with the timing weight, a difference in level occurs due to wear of the parts, which increases the sliding resistance of the timing weight and impedes the expansion/contraction fluctuation based on the centrifugal force. Therefore, the advance angle characteristic becomes unstable as shown by B (broken line) against the target characteristic A (solid line) shown in the Np-θ characteristic (θ is the timer advance angle) in FIG. When the vibration of the engine is large, such as at the time of starting, the sliding resistance increases significantly, resulting in problems such as a deviation from the target characteristic A.

This invention was developed based on these circumstances, and its purpose is to create a fuel for internal combustion engines that can prevent fluctuations in advance characteristics due to engine vibration, reduce noise, and prevent premature wear. An object of the present invention is to provide an injection timing adjustment device.

[Means to solve the problem]

That is, in this invention, buffer bodies are provided on both sides of the timing weight in the outer circumference of the timing hub, one of these buffer bodies is opposed to the timing weight with a minute gap, and this minute A feature is that the gap is set smaller than the gap between the timing weight and the flange.

[Effect]

According to such a configuration, when vibration occurs in the timing weight in the axial direction, the timing weight comes into contact with the buffer body to absorb the vibration and is prevented from colliding with the flange.
Moreover, when the timing weight is displaced by centrifugal force, the timing weight is separated from one of the buffer bodies with a small gap, so there is no fear that the buffer body will cause sliding resistance.

〔Example〕

An embodiment of this invention will be described below with reference to FIGS. 1 to 4.

In the figure, reference numeral 1 denotes a drive housing that rotates in synchronization with the engine, and is connected, for example, to the engine crankshaft (not shown) via a joint such as an Oldham joint or a laminate joint, and is connected to an engaging claw 1a. It is rotated by receiving torque.

The drive housing 1 has an outer cylinder 3 integrally attached to the outer edge of the drive flange 2, and the open end of the outer cylinder 3 is closed by a cover 5 via screws 4.

Inside the drive housing 1 is a timing hub 6.
is provided. The timing hub 6 is concentric with the drive housing 1, and is fitted into the drive housing 1 so as to be rotatable relative to the drive housing 1. A driven shaft 7 such as a camshaft of a fuel injection pump (not shown) is connected to the timing hub 6 by a round nut 8 so as to rotate together with the timing hub 6 .

The timing hub 6 also includes a drive housing 1.
A driven flange 9 is integrally formed opposite the inner side of the driving flange 2 .

Note that 10 is a sealing member that maintains liquid tightness between the drive housing 1 and the timing hub 6.

Circular holes 11, 11 are bored in the driven flange 9 at positions facing each other in the radial direction.
2 and 12 are fitted in a rotatable manner. These large eccentric cams 12, 12 have circular holes 13, 13 formed at eccentric positions, respectively.
13 each have a disk-shaped small eccentric cam 14,
14 is fitted in a rotatable manner. Small eccentric cam 1
4, 14 have first eccentric pins 15, 1 at eccentric positions.
5 are provided protrudingly, and these eccentric pins 15, 15
is press-fitted into the drive flange 2. Also,
The large eccentric cams 12, 12 have a second eccentric pin 16,
16 are provided protrudingly, and these second eccentric pins 1
6 and 16 extend along the axial direction in the space between the cover 5 and the driven flange 9, and are press-fitted and connected to a pair of timing weights 17 and 17.

The timing weights 17, 17 are located within the space, surround the timing hub 6, and have a structure divided into two parts in the radial direction.

Support rods 18, 18 are loosely inserted between the timing weights 17, 17, and these support rods 18, 18 guide the expansion and contraction movement of the timing weights 17, 17 based on centrifugal force, and also hold a return spring. are doing. In other words, spring seats 19 are fixed to both ends of the support rods 18, 18 with retaining rings or nuts, and these spring seats 19 and timing weights 17, 1
A spring 20 is spanned between the rods 18 and 7, surrounding the rods 18, 18. Therefore, the timing weights 17, 17 are pressed by these springs 20, and are biased toward each other.

A pair of shock absorbers 21a and 21b are provided on the outer circumference of the timing hub 6 on both sides of the timing weights 17 and 17 in the axial direction. In this embodiment, disc springs as shown as 21 in FIG. 3 are used as the buffer bodies 21a and 21b.

One disc spring 21a is a timing weight 17
The thrust collar 2 is interposed between the
It faces the timing weight 17 via 2a. In this case, the thrust collar 22a is in contact with the stepped portion 6a formed on the timing hub 6, and therefore the disc spring 21a has a predetermined set load to move the thrust collar 22a toward the stepped portion 6a.
is forcing it on. Timing weight 17 above
The movement of one side in the axial direction is restricted by the thrust collar 22a, so that the gap between the timing weight 17 and the cover 5 is maintained at Δl _1. .

The other disc spring 21b is the timing weight 17
and the driven flange 9, and this disc spring 21b also faces the timing weight 17 via another thrust collar 22b. When the timing weight 17 is in contact with one of the thrust collars 22a, a minute gap Δl ₃ is secured between the other thrust collar 22b and the timing weight 17. Therefore, the other disc spring 21b has no set load. Note that this minute gap Δl ₃ may occur between the disc spring 21b and the driven flange 9.

The minute gap Δl ₃ is defined by the timing weight 1 when it is in contact with the timing weight 17 and one of the thrust collars 22a.
The gap is smaller than the gap Δl ₂ between the driven flange 7 and the driven flange 9 (Δl ₃ <Δl ₂ ).

The above gaps are Δl ₁ ≒0.4mm, Δl ₂ ≒0.8mm,
Δl ₃ is set to ≒0.2mm.

Furthermore, in this embodiment, as shown in FIG. This is the thrust collar.

Next, the operation of the above-mentioned embodiment related to such a configuration will be explained.

When the drive flange 2 of the drive housing 1 is rotated in synchronization with the rotation of the engine, the small eccentric cams 14, 14 and the large eccentric cams 12, 12 are connected to the driven shaft 7 via the first eccentric pins 15, 15. Accordingly, the driven flange 9 is rotated and the timing hub 6 is also rotated. As a result, the driven shaft 7 is rotated and the fuel injection pump is driven.
At this time, the rotation of the large eccentric cams 12, 12 around their axes is transmitted to the timing weights 17, 17 via the second eccentric pins 16, 16, so these timing weights 17, 17 are connected to the drive housing 1. are rotated synchronously.

Therefore, when the rotational speed of the drive flange 2 is increased, the rotational speed of the timing weights 17, 17 is also increased, and the centrifugal force becomes large. Therefore, the timing weights 17, 17 are attached to the support rod 1.
8 and 18 are displaced in the axial direction so as to expand against each other against the biasing force of the springs 20.

Such fluctuations in the timing weights 17, 17 cause the second eccentric pins 16, 16 to move in the direction of arrow C, so the large eccentric cams 12, 12 and the small eccentric cams 14, 14 move in the direction of the first eccentric pins 15, 15. It is rotated in the direction of arrow D around . Here, the large eccentric cams 12, 12 and the small eccentric cams 14, 14
Since they are eccentric from each other, a phase difference occurs, and this phase difference causes the driven flange 9 to rotate. In other words, the timing hub 6 is rotated in the advance angle direction. Therefore, when the engine speed Np increases as the engine speed increases, the fuel injection timing θ of the fuel injection pump is advanced, and the target characteristics shown by the solid line A in FIG. 4 are obtained. be.

Note that as the engine speed decreases, the centrifugal force decreases, so the timing weights 17, 1
7 are returned toward each other by the pressing force of the springs 20..., and the target characteristic A is achieved by the reverse action.
It goes without saying that the fuel injection timing θ is retarded along the line.

According to this embodiment, when the engine is started, large vibrations are transmitted to the timing weights 17, 17, and tend to displace the timing weights 17, 17 in the axial direction. When the timing weight 17 tries to move to the left in FIG. 1, the thrust collar 22a
, and receives the pressing force of the disc spring 21a. Further, the timing weight 17 hits the thrust collar 22b which is about to move to the right in FIG. 1, and then receives the pressing force of the disc spring 21b. Therefore, no matter which direction it moves, the disc springs 21a, 2
1b prevents movement and thus absorbs vibrations. Therefore, since the gap Δl ₁ between the timing weights 17, 17 and the cover 5 and the gap Δl ₂ between the timing weights 17, 17 and the driven flange 9 can be secured, collisions caused by vibrations of the timing weights 17, 17 and collisions caused by this can be prevented. The accompanying collision noise can be reliably prevented, and the overall noise of the engine can be reduced.

Further, since collision between the timing weights 17, 17 can be prevented, wear of these timing weights 17, 17, etc. can also be prevented, and the life of the parts can be extended.

Since the other disc spring 21b does not have a set load on the timing weight 17, that is, it secures a small gap Δl ₃ , the pressing force of both disc springs 21a and 21b is not applied to the timing weight 17. Therefore, there is no sliding resistance in the radial direction of the timing weight 17 based on centrifugal force. Therefore, displacement due to centrifugal force is allowed smoothly.

In this way, the timing weight 17 is
Since displacement in the axial direction is regulated and shocks are absorbed, stable operation is possible, the unstable characteristic B shown in FIG. 4 can be improved, and the target characteristic A can be maintained with high accuracy.

Also, in this embodiment, the timing weight 1
Since synthetic resin spacers 23 and 23 are interposed between timing weights 7 and 17, these timing weights 1
7,17 Mutual collision noise can also be buffered,
This makes it possible to further reduce noise.

It should be noted that this invention is not limited to the above-mentioned embodiment, and may be constructed as other embodiments shown in FIGS. 5 to 8. In FIG. 5, the drive housing 50 is gear driven by the rotation of the crankshaft, and this housing has large eccentric cams 12, 12 and small eccentric cams 14 on the drive flange 2 side.
14 are provided. Therefore, in this case, one shock absorber, for example, the spring member 51, is provided between the timing weights 17, 17 and the drive flange 2.
is interposed between the timing weight 17 and the timing hub 6, and the other shock absorbing body, such as a spring member 52, is attached via a retaining ring 53.

One spring member 51 has a notch 51a formed around the disc spring as shown in FIG. 6, and with such a spring member 51, it is possible to improve the cushioning performance and secure the oil supply path. .

Further, the other spring member 52 is shown in FIGS.
As shown in detail in the figure, a disc spring in which the spring members 51 are integrally connected with each other facing each other is coated with a shock absorbing material 54 such as wear-resistant rubber. , which can contribute to further noise reduction.

[Effect of idea]

As explained above, this invention is characterized by providing a shock absorber with a small gap between the timing weight and the flange, and the vibrations transmitted from the engine are absorbed by the shock absorber. Collision noise of timing weights can be prevented, and by reducing the noise in this way, the engines used in vehicles do not cause discomfort to passengers, and the lifespan of parts can be extended. Furthermore, since the timing weight can be prevented from moving in the axial direction, it has various excellent effects, such as preventing fluctuations in the advance angle characteristics and maintaining the target characteristics with high precision.

[Brief explanation of the drawing]

Figures 1 to 4 show an embodiment of this invention, in which Figure 1 is a sectional view taken along line - in Figure 2, Figure 2 is a sectional view taken along line - in Figure 1, and Figure 3 is a sectional view taken along line - in Figure 1. 4 is a perspective view of a disc spring, FIG. 4 is a timer Np-θ and Np-dB characteristic diagram, FIGS. 5 to 8 show other embodiments of this invention, FIG. 5 is a sectional view, and FIG. The figure is a perspective view of the spring member, FIG. 7 is a front view of the spring member, and FIG. 8 is a sectional view taken along the line - in FIG. 7. 2... Drive flange, 6... Timing hub,
9...Followed flange, 12...Large eccentric cam, 14
...Small eccentric cam, 15...First eccentric pin, 16
...Second eccentric pin, 17...Timing weight, 21a, 21b, 51, 52...Buffer, 2
2a, 22b... Thrust collar.

Claims (1)

[Claims for Utility Model Registration] (1) A drive flange rotated by an engine,
A small eccentric cam is connected to one of the flanges via a first eccentric pin, facing a driven flange of a timing hub connected to a drive shaft of a fuel injection pump, and the small eccentric cam is eccentrically connected to a large eccentric cam. The large eccentric cam is rotatably housed in the other flange, and the large eccentric cam is connected via a second eccentric pin to a timing weight that is freely displaceable in the radial direction. Fuel injection timing adjustment that relatively angularly displaces the driving flange and timing hub by transmitting the rotation of the flange to the timing weight and transmitting the displacement based on the centrifugal force of the timing weight to the driven flange via the large eccentric cam. In the apparatus, buffer bodies are provided on the outer circumference of the timing hub on both sides of the timing weight, one of these buffer bodies is opposed to the timing weight with a small gap therebetween; A fuel injection timing adjustment device for an internal combustion engine, wherein the minute gap is set smaller than the gap between the timing weight and the flange. (2) The fuel injection timing adjustment device for an internal combustion engine according to claim (1), characterized in that a thrust collar is interposed between the buffer body and the timing weight.