JPS59134334A - Fuel injection timing adjusting device for internal- combustion engine - Google Patents

Abstract

PURPOSE:To prevent the scatter of the characteristics of a timer, by fitting a support member onto the outer surface of a timing hub coupled to the drive shaft of a fuel injection pump, and as well by securing support rods for timing weights, to the support member. CONSTITUTION:The cylindrical section 30a of a support member 30 is rotatably fitted onto the outer surface of a timing hub 6 coupled to the drive shaft of an injection pump, and the plate section 30b of the support member 30 is secured with support rods 18 for timing weights 17a, 17b. With this arrangement the axial movement of the support rods 18 are inhibited, and the bad affection of abrasion is prevented due to the posture of the support rods 18, thereby, the scatter of the characteristics of a timer may be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device that automatically adjusts fuel injection timing according to the rotational speed of an engine.

As a typical example of this type of fuel injection timing adjustment device (referred to as an automatic timer), the rotation of a drive flange connected to the engine is transmitted to a pair of timing weights, and when these timing weights are displaced by centrifugal force, this displacement is The signal is transmitted to the driven flange of the timing hub via the large eccentric cam and the small eccentric cam, and the timing hub is angularly displaced relative to the drive 7 lange, thereby advancing or retarding the drive shaft of the fuel injection pump. It is known that the fuel injection timing is rotated at an angle to relatively advance or retard the fuel injection timing.

In a device using such timing weights that are displaced in the radial direction by centrifugal force, a pair of support rods are passed between the pair of timing weights, and the movement of the timing weights is guided by these support rods. A spring is attached to the shaft to generate a biasing force for returning the timing weight. However, in such a configuration, the centrifugal force of the timing weight is small especially in the low speed rotation region, and the tension of the spring that presses the timing weight is also small, and in addition, the engine torque fluctuation is unstable.
The timing weights tend to wobble, and the postures of both timing weights tend to tilt from their normal positions. When the timing weights are tilted, the tension of the spring changes, making it difficult for the left and right timing weights to operate equally.

For this reason, for example, in the Np-θ characteristic diagram of the timer shown in FIG. 1 (Np is the rotation speed, θ is the timer advance angle), Np
In contrast to the required characteristics A in the low-speed rotation range below l, variations in characteristics such as B will occur, resulting in the engine not being able to fully demonstrate its performance in terms of output, fuel efficiency, and exhaust emissions, or the engine not being able to fully demonstrate its performance after the engine has stopped. There are problems such as poor restartability.

For this reason, in order to ensure equal operation of both timing weights, a fuel injection timing adjustment device described in ``Japanese Unexamined Patent Publication No. 57-38626'' is known. That is, in this device, both ends of each of the support rods can be slidably contacted with the inner surface of the case, thereby maintaining the correct posture of the support rods and preventing the timing weight from wobbling.

However, the fuel injection timing adjustment device described in the above-mentioned publication has a disadvantage in that the both ends of the support rod are in sliding contact with the inner surface of the case, and that both ends are likely to be worn due to the sliding contact.

For this reason, during long-term operation, as the wear progresses, a large gap is created between the inner surface of the case and both ends of the support rod, and the support rod moves axially again, causing the timing weight to wobble. Therefore, there was a problem with its durability.

The present invention was made based on these circumstances, and
The purpose is to provide a fuel injection timing adjustment device for an internal combustion engine that can ensure equal operation of both timing weights over a long period of time and that does not cause variations in timer characteristics.

That is, the present invention is characterized in that a support member is rotatably fitted onto the outer surface of the timing hub, and the central portions of the support rods are fixed to the support member.

An embodiment of the present invention will be described below based on FIGS. 2 and 4.

In the figure, reference numeral 1 denotes a drive flange, which is connected to a crankshaft (not shown) on the engine side via, for example, an Oldham coupling ring 2, and is rotated by receiving torque from a pawl 1a.

A cylindrical case 3 integrally having a closing wall 4 at the other end is attached to the drive flange 1, and this case 3 is fixed to the drive flange 1 with a gel 5°5, and is integral with the drive flange 1. is rotated to

Reference numeral 6 designates a timing knob that is concentric with the case 3 and is mounted so as to be rotatable relative to the drive flange 1 and the case 3. A drive shaft 7, which constitutes a camshaft of a fuel injection pump (not shown), is connected to the timing nozzle through a nut 8 so as to rotate therewith. Further, a driven plunger 9 is integrally formed in the timing pro, located inside the closing wall 4 of the case 3. The driven flange 9 and the drive 7 flange 1 are spaced apart from each other in the axial direction, and a space 10 is formed between these flanges 9 and 1.

The driven flange 9 is provided with circular holes 11h and Ilb at positions facing each other in the radial direction.
Disc-shaped large eccentric cams 12a and 12b are rotatably fitted into a and llb. The large eccentric cams 12m and 12b have circular holes 13 &, 13b bored at eccentric positions, respectively, and the small eccentric cams 14a and 13b are formed in these circular holes 13a and 13b.
.

14b is rotatably inserted. Small eccentric cam 14m
, 14b have second eccentric bins 15a, 15b at eccentric positions.
These second eccentric bins 25m and 15b are press-fitted into the closing wall 4 of the case 3. Further, first eccentric bins 16m, 16b are fitted to the large eccentric cams 12a, 12b, and these eccentric bins 16h, 16-b are connected to timing weights 17g, 17.
b is press-fitted and connected.

In the space 10, timing weights 17m and 17b, which are divided into two in the radial direction, are provided surrounding the timing hub 6. The above timing weight 17a, 1
7b are displaced outward based on centrifugal force, so that they are spread apart from each other. A support rod 1g and IFI are passed through between the timing weights 17h and 17b, and these support rods 1B and 1B are timing weights) J'7a,
It guides the radial movement of 77b and also supports the return sedge ring 19.

The return spring 19... is connected to each support rod 18゜1.
The spring receiver provided at the end of the frame 8 is placed between the seats 20... and the timing weights 17a, Z7b, and presses the timing weights 17h, 17b toward each other. In this case, the return springs 19... are composed of a high-speed spring 19h with high tension and a low-speed spring 19b with low tension, and there is a gap between these high-speed springs 19a and low-speed springs 19b. A plate 25 is interposed in the sliding spring receiver that slides along the support rod 18. In the low speed rotation range of the engine, the low speed spring 19b is mainly pushed, and in the high speed rotation range, the low speed spring 19b bottoms out, so the high speed spring 19a is pushed.

The first eccentric bins 16h, 16b are press-fitted into timing weights 17m, 17b, and the movement of the timing weights 17h, 17b is controlled by large eccentric cams 12m, 12.
b. - As shown in FIG. 2, a thrust bearing plate 21 is provided between the inner surface of the drive flange 1 and the timing weights 17a, 17b. The thrust receiver plate 21 is fitted onto a step 22 formed on the timing plate, and is positioned so as not to move toward the timing weights 17g and 17b while being rotated integrally with the timing plate. And the thrust receiver is a grate 21 and a timing weight 17h, 17
A gap t of approximately 0.05 wm+ is ensured between b.

Further, another thrust bearing grate 23 is provided between the closing wall 4 of the case 3 and the driven flange 9. In this thrust receiver, the plate 23 is also fitted into a stepped portion 24 formed in the timing plate to secure a minute gap S between the closing wall 4 and the driven flange 6, and to prevent them from coming into contact with each other. ing.

Such a thrust bearing is provided by plates 21 and 23.
The axial dimension of the space 10 is kept constant.

The timing hub 6 is provided with a support member 30. This support member 30 has a cylindrical portion 30a.
and a pair of plate portions 3θb.

30b, and this cylindrical portion 30a is the timing hub 6.
is rotatably fitted to the outer surface of the

Further, the grate portions 30b, 30b are integrally provided on the outer surface of the cylindrical portion 30a and extend in the radial direction facing away from each other, respectively.
It is located between 7g and 17b. The support rods 1B and 18 are connected to the grate portions sob and sob of the support member 30, respectively. That is, these support rods Ill and 1B are equidistant from the rotation center of the timing hub 6 and are connected to the plate portions 30b and 30b, respectively.
The central part of the plate portion 30
b, 30b by welding or brazing.

Based on this configuration, the operation of the embodiment will be explained.

When the rotation of the engine is transmitted to the drive flange 1 via the Oldham coupling 2, the case 3 and the closing wall 4
is rotated together with the drive flange 1. The closing wall 4 is the second
Eccentric bin 15a.

Since the small eccentric cams 14h, 14b and the large eccentric cams 12h, 12b are rotated around the drive shaft 7 via the driven flange 9, the timing hub 6 is rotated via the driven flange 9. Therefore, the rotation on the engine side is transmitted to the drive shaft 7 and drives the fuel injection pump.

Drive 7 lunge 1. The rotation of the case 3 and the timing hub 6 is controlled by the timing weight 17&.

Rotate 17b.

When the rotational speed of the drive flange side is increased, the rotational speed of the timing weights 17m and 17b is also increased,
Therefore, based on the centrifugal force, the timing weights 17a and 17b are expanded and displaced against the return springs 19. The outward movement of the timing weights 17&, 17b pushes the first eccentric bins 16a, 16b in the direction of the arrow in FIG.
It is rotated in the direction of arrow E within Ilb. Large eccentric cam 12a
, 12b in the direction of arrow E is caused by small eccentric cams 14h, 1
4b in the direction of arrow E. At this time, the small eccentric cams 14&, 14b are connected to the first eccentric bins 15a,
Since the small eccentric cams 14h and 14b are connected to the closing wall 4 by the cam 15b, the small eccentric cams 14h and 14b try to rotate in the direction of the arrow F while revolving in the direction of the arrow E. Therefore, the large eccentric cam 12m, 12
b and the small eccentric cam 14a.

14b mutually generate a phase difference, and this phase difference is absorbed by advancing the driven flange 9. The driven flange 9 advances the drive shaft 7 via a timing weight.

As a result, the injection timing θ of the fuel injection pump can be advanced with respect to the engine rotational speed Np.

Basically, it is possible to obtain the timer characteristics as described above, but for example, the first eccentric bin 1 shown in FIG.
5m and 15b, in advance from the line connecting the center point of the large eccentric cams 12g and 12b and the center line of the timing weight.
If it is set to be offset in the direction, the first eccentric pin 16
a.

When 16b is moved in the direction of arrow F, the second eccentric bins 15m and 15b are rotated in the opposite direction to the direction of arrow F. That is, the timing weight is rotated to the retard side. With such a setting, the fuel injection timing is relatively advanced in advance at the time of starting the engine and at low rotation speeds to increase the fuel combustion efficiency, thereby improving exhaust gas countermeasures.

According to such a setting, in the timer characteristic diagram shown in Fig. 1, the fuel injection timing θ is set to the advanced side at engine startup and low engine speed, and the engine speed is changed from Npl to Npl.
At a rotation speed of p2 or more, return to the retard side by one, and then turn N
Characteristic A can be realized in which the angle is advanced when the rotational speed becomes p2 or higher.

By the way, in this embodiment, the support member 30 is rotatably fitted to the timing plate, and the center portions of the support rods I8, 1B are fixed to the support member 30, so that these support rods 1B, 1B are It does not move in the axial direction, that is, in the direction in which the timing weights 17a and 17b are expanded, and is not displaced or tilted, and is always maintained in a compressed position. Therefore, in the timing weights 17m and 17b, the support rods 1B and 1
Since the return springs 19b are restrained by B and their rattling can be reliably prevented, the tension of the return springs 19b can be maintained evenly. Therefore, the biasing force of the return spring 19b is correctly transmitted to the timing weights 17a, 17b.

Since the movement of 17b can be maintained evenly,
So-called timing weight 17a.

17b can be prevented and the required characteristic A shown in FIG. 1 can be satisfied. As a result, it is possible to reliably improve the engine output and fuel efficiency based on the above-mentioned required characteristic A, and it is also excellent in terms of exhaust gas countermeasures.

Since both ends of the support rods Ill, 18 are not in sliding contact with the inner surface of the case 3 to maintain their posture, they are not adversely affected by wear or the like. Therefore, even during long-time operation, the support rod 1B
, 18 can be maintained correctly and the above-mentioned required characteristic A can be satisfied for a long time, and it is also excellent in terms of durability.

Note that the present invention is not limited to the above embodiments.

For example, when implementing the present invention, the present invention is not limited to a timer having a timer characteristic of once retarding and then advancing as shown in characteristic A in FIG. 1, but can be applied to timers having various A-turn timer characteristics. Further, it goes without saying that the specific structure for attaching the eccentric cam etc. is not limited to that of the above embodiment, and can be implemented with various modifications.

〔Effect of the invention〕

As described in detail above, according to the present invention, the support member is rotatably fitted to the timing hub, and the center portion of each support rod is fixed to this support member, so that these support rods are fixed in the axial direction. Movement is definitely prevented. Therefore, the movement of each timing weight is constrained by the support iron and becomes uniform, thereby preventing variations in timer characteristics and satisfying the required characteristics with high precision.

Further, since the attitude maintenance of the support rod is not adversely affected by wear or the like, the above-mentioned required characteristics can be maintained for a long period of time, resulting in excellent durability.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the Np-θ characteristics of the timer, FIGS. 2 to 4 show an embodiment of the present invention, and FIG.
3 is a sectional view taken along line 1--1 in FIG. 2, and FIG. 4 is a perspective view of the support member. 1... Drive 7 lunge, 6... Timing hub, 7...
... Drive shaft, 9... Driven flange, 12g, 12b.
...Large eccentric cam, 14m, 14b...Small eccentric cam, 1
6a, 16b---first eccentric pin, 15a. 15b...Second eccentric pin, 17a, 17b...Timing weight, Ill, 1B...Support rod, 1
9...Return spring, 19a...High speed return spring, 19b...Low speed return sgering, 21.
... Thrust receiver is plate, 30... Support member,
30m...Cylindrical part, 3b, 3b...Plate part O

Claims (1)

[Claims] The rotation of the drive flange driven by the engine is transmitted to a pair of timing weights, and these timing weights are guided by a pair of support rods that are passed between these timing weights by centrifugal force, and are attached to these support rods. The timing weights are expanded in the radial direction against the biasing force of the spring, and the expansion displacement of these timing weights is transmitted to the large eccentric cam via the first eccentric bin, and the large eccentric cam is eccentrically rotated. The rotation of the small eccentric cam is transmitted to the supported small eccentric cam, and the rotation of this small eccentric cam is transmitted to the second small eccentric cam.
In a fuel injection timing adjustment device that transmits information to a timing hub connected to a drive shaft of a fuel injection pump by an eccentric pin, and relatively angularly displaces the drive flange and the timing hub according to rotational speed, A fuel injection timing adjustment device for an internal combustion engine, characterized in that a rotatable support member is fitted into the support member, and a central portion of each of the support rods is fixed to the support member.