JPS6231648Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a fuel injection timing adjustment device for an internal combustion engine.

[Conventional technology]

Conventionally, the lift of centrifugal weights that are spread apart by centrifugal force is used to drive an eccentric cam mechanism, and between a first rotary body connected to an engine and a second rotary body connected to an injection pump. A fuel injection timing adjustment device that generates a rotational phase is disclosed in, for example, Japanese Patent Laid-Open No. 54-3617.

In this prior art, as shown in FIG. 1, a disk-shaped second rotating body 3 is placed inside a cup-shaped first rotating body 4 that is rotationally driven in synchronization with a diesel engine.
A cylindrical shaft 16 integrally provided at the center of the second rotating body 30 is connected to a fuel injection pump. A pair of holes 30a are formed in the second rotating body 30 symmetrically with respect to the axis 16, and each hole 30a
A first eccentric cam 5 is rotatably fitted inside the hole, and a hole formed eccentrically in the first eccentric cam 5 is rotatably fitted into the first eccentric cam 5.
A second eccentric cam 15 is rotatably fitted to 5a.

A pair of centrifugal weights 14 are arranged to sandwich the shaft 16, and both ends of the centrifugal weights 14 are connected to a pair of guide shafts 24.
are expandably connected to each other. Guide shaft 24
A spring 2 that counters the centrifugal force of the centrifugal weight 14 is installed at both ends of the
2 is supported. The first eccentric cam 5 is a centrifugal weight 14
The second eccentric cam 1 is supported by a pin 13 provided in the
5 is supported by a pin 6 provided on the first rotating body 4. Therefore, the driving force of the first rotating body 4 is transmitted to the second rotating body 30 via the pin 6 and the second and first eccentric cams 15 and 5.

As shown in FIG. 2, the first and second rotating bodies 4,
The central angle α between the center A of the pin 6 and the center C of the first eccentric cam 5 with respect to the axis O of the rotor 30 is determined by the increase in the rotational speed of the first and second rotating bodies 4 and 30 in the direction of the arrow x. Therefore, it changes as follows. When the centrifugal weights 14 are spread apart by centrifugal force as the engine speed increases, the center D of the pin 13 is aligned with the first eccentric cam 5.
It moves in the direction of arrow y centering on the center C of . arm
DC and arm CB are integrally located at the center C of the first eccentric cam 5.
The center A of the pin 6 moves to the right in the figure, and the center A of the pin 6 and the center A of the first eccentric cam 5 move around the axis O of the first and second rotating bodies 4 and 30. The central angle α formed with the center C gradually becomes smaller, and the engine injection timing advances. The rotational speed at which this advancement starts is determined by the load of the spring 22 that biases the pair of centrifugal weights 14 in the direction of closing them together.

However, in the conventional fuel injection timing adjustment device described above, the hole 5a that accommodates the second eccentric cam 15 and the hole of the pin 13 that supports the centrifugal weight 14 must be arranged inside the first eccentric cam 5. Must be. Providing such two holes in the limited space of the first eccentric cam 5 limits the degree of freedom of the advance angle characteristic of the eccentric cam mechanism 10, making it difficult to adjust the advance angle characteristic at low engine speeds. When the centrifugal weight 14 is lifted up, the lift of the centrifugal weight 14 cannot be used effectively.

That is, in the conventional example shown in FIG. ), and the pin 13 that supports the centrifugal weight 14 is offset toward the axis of the rotating body of the first eccentric cam 5 (the position shown by the chain line in FIG. 2).
However, this is not possible since this portion is occupied by the second eccentric cam 15. If this is desired, the first eccentric cam 5 must be made larger, but this increases the outer diameter of the entire device, which is not preferable.

[Problem that the invention attempts to solve]

In view of these problems, the purpose of the present invention is to provide a fuel injection system in which the first eccentric cam, the second eccentric cam, and the pin of the centrifugal weight can be freely disposed in the limited space of the rotating body without interfering with each other. An object of the present invention is to provide a timing adjustment device.

[Means for solving problems]

In order to achieve the above object, the present invention has a configuration including a cylindrical first rotating body connected to one of the engine and the fuel injection pump, and a cylindrical first rotating body connected to the other and concentric with the first rotating body. A disc-shaped second rotating body is housed, an eccentric cam mechanism that connects the first rotating body and the second rotating body, and a hydraulic actuator that drives the eccentric cam mechanism. The eccentric cam mechanism has a first eccentric cam housed inside the first rotating body and a second eccentric cam housed inside the second rotating body, which are connected by a pin.

[Effect]

By separating the second eccentric cam 35 from the first eccentric cam 5 and supporting it on the first rotating body 4 that is different from the second rotating body 30 that supports the first eccentric cam 5, the first Since the second eccentric cam 35 can be freely arranged with respect to the eccentric cam 5, the piston 25 of the hydraulic actuator 20 is placed in the portion of the first eccentric cam 5 that approaches the axis O of the rotating body. It becomes possible to arrange the pin 13 that connects the piston 25, and the displacement of the pin 13 relative to the lift of the piston 25 can be increased.

[Example of idea]

The present invention will be explained based on examples. 3rd, 4th
As shown in the figure, a cylindrical portion 35a is provided on the front wall 40 of the first rotating body 4 connected to the engine, and a second
The eccentric cam 35 is rotatably supported. On the other hand, a disk-shaped second rotating body 30 is provided inside the first rotating body 4.
concentrically and rotatably accommodated, and a hole 5 provided therein.
A first eccentric cam 5 is rotatably supported inside a. Then, with the pin 36, the first eccentric cam 5
and the second eccentric cam 35 (see FIG. 5).

A pair of hydraulic actuators 20 facing each other on the open end side of the first rotating body 4 are housed close to the second rotating body 30 and the first eccentric cam 5, and a lid plate 37
The second rotary body 30 and the hydraulic actuator 20 are configured not to move in the axial direction inside the first rotary body 4. The shaft 16, which is integral with the second rotating body 30, is supported by a bearing 38 on the end wall 40 and a bearing 39 on the cover plate 37 so as to be relatively rotatable.

A pair of hydraulic actuators 20 arranged to sandwich the shaft 16 each have a piston 25 fitted into a cylinder 27 to define a liquid chamber 31 on the inner end thereof, and a spring in a chamber 32 on the outer end. 28 is accommodated. Pressure liquid from a hydraulic pressure source (not shown) is supplied to the liquid chamber 31 through the inlet 26, and the piston 25 is pushed radially outward against the force of the spring 28. The lift of the piston 25 is controlled by hydraulic pressure that is adjusted depending on the engine speed, load, etc.

The pin 13 is supported on the piston 25 of the hydraulic actuator 20, and the pin 13 is inserted into the slit 2 of the cylinder 27.
It is connected to the first eccentric cam 5 via 9.

In addition, in the above-mentioned embodiment, the second rotating body 3
0 to the engine and the first rotating body 4 to the fuel injection pump, similar effects can be obtained.

Next, the operation of the fuel injection timing adjustment device according to the present invention will be explained. As shown in Figure 6, the second
The center of the eccentric cam 35 is A, and the center of the second eccentric cam 35 is
Assuming that the center of the pin 36 connecting the and first eccentric cam 5 is B, the center of the first eccentric cam 5 is C, and the center of the pin 13 is D, the same effect as in the conventional example shown in FIGS. 1 and 2 is obtained. do.

That is, the engine rotates the first and second rotating bodies 4,
30 is rotated in the direction of arrow x. When the hydraulic pressure in the liquid chamber 31 of the hydraulic actuator 20 increases in relation to the engine speed, load, etc., the piston 2
5, the pin 13 moves away from the axis O, and the arm
DC and arm CB rotate together around center C, and arm
The bending angle of CB and arm BA gradually increases in accordance with the hydraulic pressure, and the central angle α between centers A and C with respect to axis O increases, and the injection timing is retarded as shown by line 21 in Fig. 7. do.

Then, when arm CB and arm BA are aligned, the central angle α becomes maximum, and the injection timing at this time is the latest.

When the hydraulic pressure in the liquid chamber 31 of the hydraulic actuator 20 becomes higher, the arms CB and BA bend toward the axis O, the center angle α gradually decreases, and the injection timing of the engine is advanced.

In the above embodiment, the eccentric cam mechanism 10 has retardation/advance characteristics, but if necessary, if the eccentric cam mechanism 10 is arranged as shown in FIG. 8, it can be made to have only an advance characteristic.

[Effect of idea]

As described above, the present invention separates the second eccentric cam 35 from the first eccentric cam 5 and attaches it to the first rotating body 4 that is separate from the second rotating body 30 that supports the first eccentric cam 5. Since the second eccentric cam 35 is supported, the second eccentric cam 35 can be freely arranged with respect to the first eccentric cam 5. As a result, the first eccentric cam 5
It becomes possible to arrange the pin 13 that connects the piston 25 at a portion approaching the axis O of the rotating body, and the displacement of the pin 13 relative to the lift of the piston 25 can be increased. In other words, since the entire range of changes in the lift of the piston 25 can be effectively used for the operation of the eccentric cam mechanism 10, effective advance angle characteristics can be obtained even at low engine speeds.

[Brief explanation of drawings]

Figure 1 is a front sectional view of a conventional fuel injection timing adjustment device, Figure 2 is a front view of the eccentric cam mechanism of the same device,
Fig. 3 is a side sectional view of the fuel injection timing adjustment device according to the present invention, Fig. 4 is a front sectional view taken along the line - in Fig. 3, and Fig. 5 is an exploded perspective view of the eccentric cam mechanism of the device. , FIG. 6 is a front view illustrating the operation of the eccentric cam mechanism of the device, FIG. 7 is a diagram showing the operating characteristics of the device, and FIG. 8 is a partially modified embodiment of the present invention. It is a front view similar to. 4...first rotating body, 5...first eccentric cam,
10... Eccentric cam mechanism, 16... Shaft, 20... Hydraulic actuator, 25... Piston, 30...
Second rotating body, 31...Liquid chamber, 35...Second eccentric cam, 36...Pin.

Claims (1)

[Scope of utility model registration request] A cylindrical first rotating body connected to one of the engine and the fuel injection pump, and a disc-shaped second rotating body connected to the other and housed concentrically in the first rotating body.
a rotating body; an eccentric cam mechanism that connects the first rotating body and the second rotating body; and a hydraulic actuator that drives the eccentric cam mechanism; A fuel injection timing adjustment device characterized in that a first eccentric cam housed inside a first rotating body and a second eccentric cam housed inside the second rotating body are connected by a pin.