JPS6314033Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an injection timing control device for a fuel injection pump of a diesel engine or the like.

In a diesel engine, the fuel injection timing is variably controlled according to the engine speed, and in particular, at startup, the injection timing is advanced by a predetermined value to improve startability and engine stability.

For this purpose, a distribution type fuel injection pump is known which is equipped with an injection timing advance device as shown in FIGS.

In FIG. 1, fuel is sucked from an inlet 1 of a pump body through a feed pump 3 driven by a drive shaft 2 in synchronization with the engine.

The fuel in the pump chamber 5 lubricates the working parts and at the same time is sent to the high pressure plunger pump 7 through the suction port 6.

A plunger 8 of this pump 7 is fixed to an eccentric disk 9, and is driven by the drive shaft 2 via a joint 2A.

The eccentric disk 9 has the same number of face cams 10 as the number of engine cylinders (not shown), and the face cams 10 are arranged on roller cylinders 11.
It moves back and forth by a predetermined cam lift while rotating over the same number of rollers 12 as .

Therefore, the plunger 8 reciprocates while rotating, and as a result of this reciprocating movement, the fuel sucked from the suction port 6 is forced to be sent from the distribution port 13 through the delivery valve 14 to an injection nozzle (not shown). .

The fuel injection amount is determined by the position of a spill ring 16 that covers a spill port 15 formed in the plunger 8. For example, when the spill ring 16 moves to the left and the plunger 8 moves to the right, the communication of the spill port 15 to the low pressure pump chamber 5 is accelerated.
The release timing of high-pressure fuel is advanced (injection end timing is advanced), and the amount of fuel injection decreases.

The position of the spill ring 16 is controlled via a link lever 19 by the movement of a governor mechanism 18 driven by the rotation of the drive shaft 2, and the amount of fuel injection is increased or decreased in accordance with the engine speed.

Note that FIG. 1 shows the axis of the plunger 24 rotated by 90 degrees, and for convenience of explanation, the axis of the feed pump 3 is also shown rotated by 90 degrees.

The fuel injection start timing is determined by the timing when the face cam 10 rides on the roller 12, and is therefore controlled by rotating the roller ring 11.

The eccentric disk 9 integrally formed with the plunger 8 rotates in the direction of arrow F in FIG. 2 during operation.

Fuel injection is performed when the face cam 10 of the eccentric disk 9 rotates and rides on the roller 12, so to advance the angle, rotate the roller ring 11 in the opposite direction of arrow F, and the face cam 10 rides on the roller 12. The earlier the time when the engine starts to run on the engine, the earlier the start time of fuel injection will be.

Advancement of the roller ring 11 is achieved by sliding of a drive pin 21 integrally formed therein and a piston 24 that engages with the drive pin 21, as shown in FIG.

A portion of the fuel in the pump chamber 5 flows into the housing 31 through a passage 25 provided in the piston 24 . Therefore, when the fuel pressure in the pump chamber 5 increases as the engine rotates, the piston 24 moves to the left against the spring 20, rotating the roller ring 11 and roller 12 in the opposite direction to the arrow. Let it advance.

On the other hand, in a diesel engine, in order to improve starting, the roller ring 11 is advanced at the time of starting to advance the fuel injection timing.

For this reason, normal distribution pumps are equipped with a manual advance device, which manually operates the drive pin 21 via the piston 24 at the time of startup.
I'm starting to be able to advance.

That is, when the lever 22 is pulled toward the user at startup, the cam 23 integrally formed with the lever 22 rotates eccentrically about the shaft 22A. This cam 23
is in contact with a piston 24 whose end surface is inclined, and as the cam 23 rotates, the piston 24 is moved to the left against the drag force of the spring 20. Then, the roller ring 11 integrally formed with the piston 24 rotates counterclockwise,
In other words, the angle is advanced and the injection timing is advanced.

However, with such conventional injection timing control devices, the injection timing is advanced manually at startup, so the lever 22 must be continuously pulled during startup, or a device with a stopper is required. If so, you would have to push the lever 22 back to its original position after the complete explosion, and you might forget to push it or
There was a problem that it required extra effort while driving.

Moreover, as shown in FIG.
discloses a device for adjusting the initial position of the piston 24, but this also has the problem that it takes too much time and effort to manually adjust it at the time of startup.

The present invention was developed with a focus on the above problem, and includes a shim made of a shape memory alloy that displaces the piston against the spring at low temperatures, and automatically advances the starting angle according to the fuel temperature. The purpose is to

Embodiments of the present invention will be described below with reference to the accompanying drawings. Components that are the same as those of the conventional example are given the same reference numerals.

As shown in FIG. 4, a shim 37 made of a shape memory alloy is interposed in a space 36 defined by the side surface 34 and the piston end surface 35 inside the housing 31.

Regarding shape memory alloys, please refer to the technical magazine "NlKKEl MECHANICAL 1980.1.21, page 54"
etc. is known.

The material of shim 37 is Cu-Zn-Al alloy, Ti-Ni.
Among memory alloys such as alloys and Au-Cd alloys, select those that have the characteristic of shrinking significantly when the temperature of the fuel oil increases after the engine is warmed up.

According to the above configuration, when starting with a low fuel oil temperature, the shim 37 deforms to enlarge the space 36, as shown in FIG. 5, and moves the piston 24 to the left against the resistance of the spring 20. , drive pin 2
1, the roller ring 11 rotates counterclockwise, that is, advances the injection timing, and improves engine starting.

On the other hand, as the engine warms up and the fuel oil temperature rises, the shim 37 contracts. For this reason, piston 2
4 returns to the initial position by the elastic force of the spring 20, returning the fuel injection timing after warm-up to the proper state.

As another embodiment, as shown in FIG. 6, a shim 37 made of a shape memory alloy is inserted in the middle of the piston 24 to provide a sandwich portion 38.

Therefore, when starting at a low temperature, the piston 24 becomes longer due to the extension of the sanderch portion 38, and the roller ring 11 is rotated in the advance direction via the drive pin 21, thereby advancing the injection timing.

As described above, in the present invention, since a shim made of a shape memory alloy is interposed at the end or inside of the timer piston, the starting advance angle can be automatically adjusted according to the fuel temperature. In particular, according to the present invention, as described above, the shim serving as a means for driving the timer piston according to the fuel oil temperature is housed inside the timer piston mechanism, so that unlike conventional devices, some kind of adjustment drive is required. Compared to a mechanism that must be installed outside the timer piston mechanism, the structure is significantly simpler, and weight, size, and cost can be significantly reduced, and shape memory alloys can be processed into precise dimensions. The effect is that the position of the timer piston can be controlled with extremely high accuracy.

[Brief explanation of drawings]

FIG. 1 is an overall sectional view of a conventional distribution type fuel injection device, and FIG. 2 is a sectional view of a conventional injection timing control device. FIG. 3 is a sectional view of another conventional example of an injection timing control device. 4 and 5 are cross-sectional views showing an embodiment of the present invention. FIG. 6 is a sectional view showing another embodiment. 11...roller ring, 20...spring, 24...
...Piston, 31...Housing, 37...Shim.

Claims (1)

[Scope of utility model registration request] In a distribution type fuel injection pump for a diesel engine, a piston connected to a roller ring is provided in the housing, and a spring is provided between the piston and the housing to bias the piston in a retard direction, and the spring is opposite to the spring. A fuel injection timing control device characterized in that a shim made of a shape memory alloy that expands when the fuel oil temperature is low and contracts when the fuel oil temperature is high is interposed between the side housing and the piston or inside the piston.