JPS6228657Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an adjustment device that advances or retards the timing of fuel injection from a fuel injection pump depending on the operating conditions of an internal combustion engine.

As this kind of fuel injection timing adjustment device, special public
The one published in Publication No. 16852 is known.

In this conventionally known device, when hydraulic oil is added to the piston via a switching valve that is switched according to the rotational speed of the internal combustion engine, the sleeve is moved in the axial direction together with the piston, and the sleeve is rotated freely. The abutted splined cone is also adapted to be moved in the axial direction. This splined cone is connected to the drive shaft on the internal combustion engine side so that it can move freely in the axial direction and rotate integrally with the drive shaft, and is also engaged with the flyweight holder by a helical spline, so that the piston is moved. Accordingly, the helical spline structure transmits the rotation of the drive shaft to the flyweight holder at a variable speed, and the camshaft for driving the fuel pump, which is connected to the flyweight holder, is transmitted at a variable speed from the drive shaft. In other words, the timing is delayed and the rotation is made. When the flyweight holder reaches a predetermined rotational speed or higher, the centrifugal force of the flyweight attached to the holder pushes the splined cone toward the piston against the spring, thereby causing the splined cone to move toward the piston. Due to the action of the helical spline structure, the rotation of the drive shaft is transmitted to the camshaft for driving the pump at different speeds, that is, with advanced timing.

However, in the adjustment device having the above conventional structure, the piston is fluid-tightly fitted to the drive shaft using an O-ring or the like, so that the piston is dragged and rotated as the drive shaft rotates. Therefore, the piston not only rotates and slides against the inner surface of the cylinder part of the casing, but also slides in the axial direction based on the hydraulic pressure, so the piston and casing are likely to wear out, causing early loss of liquid tightness. However, there was a problem with the product being inferior in durability. Furthermore, since relative rotational sliding and axial sliding occur between the piston and the drive shaft, the O-ring is likely to wear out or break due to twisting, resulting in early oil leakage. be. Furthermore, since the spring spanned between the piston and the sleeve is a large cylindrical coil spring that wraps around the outer circumference of the drive shaft, the effective diameter of the spring changes when the relative distance between the splined cone and the piston changes. If the piston is large and the piston is rotated, the spring will be twisted, and as a result, the spring characteristics, that is, the spring tension, will change greatly, causing hysteresis in the timer characteristics (rotation speed vs. injection timing characteristics). There were drawbacks such as:

The present invention was developed based on these circumstances, and its purpose is to improve the sealing performance and wear resistance of the piston by making it possible to move only in the axial direction without rotating the piston. An object of the present invention is to provide a fuel injection timing adjustment device for an internal combustion engine in which the occurrence of hysteresis based on spring characteristics is reduced by arranging a plurality of devices in parallel along the circumferential direction of the fuel injection timing device.

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

In the figure, 1 is a casing constituting a cylinder, one end of which is fixed to a fixed flange 2 which also serves as a cover. The fixed side flange 2 above has bolts 3
It is attached to the housing 4 of the fuel injection pump via... A piston 5 is fitted into the casing 1 so as to be slidable in the axial direction. A guide groove 6 is formed along the axial direction on the outer peripheral surface of the piston 5.
is formed. An overflow valve 7 is screwed onto the casing 1 so as to face the guide groove 6, and a stopper 8 which is fitted into the guide groove 6 is protruded from the tip of the overflow valve 7. The stopper 8 and the guide groove 6 allow sliding movement in the axial direction but prevent movement in the circumferential direction, so that the piston 5 is engaged with the casing 1 in a non-rotatable manner.

A plurality of spring accommodating recesses 9 are formed along the circumferential direction on the outer periphery of the piston 5, and each of the spring accommodating recesses 9 holds a spring 1.
0... is accommodated. Therefore, spring 1
0... are arranged parallel to each other along the circumferential direction of the piston 5. The other end of each spring 10 is in contact with the end surface of the casing 1, so that the springs 10 press the piston 5 to the right in FIG.

Sliders 11a and 11b are fitted into the inner surface of the piston 5 at positions facing each other.
These sliders 11a, 11b are configured to be moved integrally with the piston 5 in the axial direction by a stopper 12 and a circlip 13 formed on the piston 5.
11b can freely slide in the circumferential direction with respect to the piston 5.

The sliders 11a and 11b are fitted into a boss portion 14a of a movable flange 14 attached to close the other end of the casing 1.
Therefore, when the movable flange 14 is rotated, these sliders 11a and 11b also come into sliding contact with the inner surface of the piston 5 and are rotated together.

A splined cone 15 is rotatably fitted into the inner surface of the boss portion 14a of the movable flange 14. Splined cone 15 and the above slider 1
1a and 11b are helical spline parts 16, respectively.
a, 16b. Therefore, the sliders 11a, 11b and the splined cone 15
This means that the circumferential speed can be changed relatively.

The splined cone 15 has a pump drive shaft 1 such as a camshaft for driving a fuel injection pump.
7 are connected. The pump drive shaft 17 passes through the stationary flange 2 and is introduced into the splined cone 15, and is integrally connected to the splined cone 15 via a tapered portion 17a and a round nut 18. Note that 19a indicates an oil seal.

Although not shown, the movable flange 14 is connected to rotate in synchronization with the crankshaft of the internal combustion engine, so that the rotation of the internal combustion engine is caused by the movable flange 14, the sliders 11a and 11b, and the splinted cone 15. The signal is transmitted to the pump drive shaft 17. Note that 19b is the movable flange 1
4 and the casing 1; 20 is the movable flange 14 and the round nut 1;
This is an O-ring provided between 7 and 7.

Further, the piston 5 is provided with an O-ring 21 on its sliding surface with the casing 1, and the fixed flange 2 is provided with an O-ring 22 between it and the piston 5. A space surrounded by the piston 5, casing 1, and fixed flange 2 constitutes a pressure chamber 25. This pressure chamber 25 is the oil passage 2
6 and communicates with the oil guide valve 27. The oil guide valve 27 is connected to the pressure control valve 2 via a pipe 28.
9 and this pressure control valve 2
9 communicates with a hydraulic pump 30 such as a gear pump and an oil reservoir 31.

The pressure control valve 29 is controlled by the microcomputer 3.
The microcomputer 32 controls the internal combustion engine's rotational speed, load, cooling water temperature, intake pressure, etc., based on an instruction signal from the internal combustion engine 2. The pressure control valve 29 is controlled by detecting various factors involved in combustion by a known detection means, comparing this detection signal with a preset reference value, and outputting an appropriate instruction signal. It's becoming like that.

Furthermore, inside the casing 1, the space surrounded by the piston 5, the fixed side and movable side flanges 2 and 14, the splined cone 15, etc.
The same hydraulic oil as that stored in the oil reservoir 31 is filled as lubricating oil, and this hydraulic oil is supplied to the oil holes 3 formed in the sliders 11a and 11b.
2. The oil flows through the oil hole 33 formed in the piston 5. And the aforementioned guide groove 6
An oil hole 34 is also formed in the guide groove 6 , and hydraulic oil flows into and out of the guide groove 6 as the volume changes based on the axial displacement of the piston 5 . The guide groove 6 is communicated with the oil reservoir 31 via the above-mentioned overflow valve 7 and pipe 35, and the hydraulic oil flowing into and out of the guide groove 6 is communicated with the oil reservoir 31 via the overflow valve 7 and pipe 35. It's starting to come and go.

The operation of the embodiment having the above configuration will be explained.

When the movable flange 14 is rotated as the engine rotates, the sliders 11a and 11b fitted into the boss portion 14a of the flange 14 are also rotated together, and are engaged with these sliders 11a and 11b by a helical spline. The splined cone 15 that is also rotated integrally. Therefore, since the pump drive shaft 17 is rotated, the pump drive shaft 17 is rotated via the movable flange 14 due to the rotation of the engine.

By the way, in a state where hydraulic oil is not pumped into the pressure chamber 25 from the hydraulic pump 30, the piston 5
is pushed to the right by the springs 10, as shown by the imaginary lines in FIG. 1, and the sliders 11a and 11b are also moved to the right.

Then, the microcomputer 32 detects the combustion state of the engine and, for example, when the rotational speed increases, the pressure control valve 29 is operated to forcefully feed hydraulic oil from the hydraulic pump 30 to the pressure chamber 25 through the pipe 28. When the oil pressure in the pressure chamber 25 increases, the piston 5 is moved to the left in the figure against the spring 10.
The axial movement of the piston 5 is carried out by sliders 11a and 11.
b are integrally moved in the axial direction. The movement of the sliders 11a, 11b in the axial direction is controlled by the splined cone 15 which is engaged with the sliders 11a, 11b by a helical spline.
advance. In other words, the pump drive shaft 17 is advanced relative to the movable flange 14.

Also, based on the command signal from the microcomputer 32, the pressure control valve 29 is operated to control the pressure chamber 2.
When the pressure of the piston 5 is lowered, the piston 5 is pushed by the springs 10 and is moved to the right in the drawing. As a result, the sliders 11a and 11b are also moved to the right, so that the splined cone 15 is retarded based on the helical spline engagement. In other words, the pump drive shaft 17 is retarded relative to the movable flange 14.

For this reason, the fuel injection timing in the fuel injection pump is controlled by the microcomputer 3.
The advance angle and the retard angle are automatically controlled based on the signal No. 2.

However, according to the configuration of the above embodiment, since the piston 5 is restricted to slide only in the axial direction by the guide groove 6 and the stopper 8, the sliding movement between the piston 5 and the casing 1 is prevented. Only in the axial direction, therefore, wear between the piston 5 and the casing 1 is reduced. Moreover, since the piston 5 moves only in the axial direction, the O-rings 21 and 22 are not subjected to torsional deformation, and therefore the O-rings 21 and 22 are less likely to be cut, thereby preventing problems such as oil leakage. In addition, since a plurality of springs 10 are arranged along the circumferential direction of the piston 5, each spring 10 can be made smaller.As a result, when the spring is bent, the change in effective diameter is small, and the piston 5 rotates. Since the spring 10 is not twisted, no torsion is generated in the spring 10.
Therefore, the rate at which hysteresis occurs in the timer characteristics is reduced, making it possible to improve accuracy.

FIG. 3 shows a modification of the present invention, in which a stopper 8 formed at the tip of the overflow valve 7 is covered with a collar 40 made of a wear-resistant material. The stopper 8 has a diameter smaller than that of the embodiment shown in FIG. 2, and a collar 40, which has been hardened, for example, is fitted with a clearance on the outside thereof. The collar 40 is fitted with a clearance within the guide groove 6,
This not only prevents the stopper 8 from being worn out, but also improves its slidability in the guide groove 6.

As detailed above, the present invention prevents the piston from rotating relative to the casing by slidably fitting the stopper provided on the casing into the guide groove formed along the axial direction on the outer circumferential surface of the piston. Since the piston and casing are fitted so that they can slide only in the axial direction, there is less wear between the piston and the casing, and there is no torsional deformation of sealing members such as O-rings that keep the piston liquid-tight. Leakage is reduced and lifespan is extended. In addition, since a plurality of springs are arranged side by side in the circumferential direction of the above piston, there is little change in the effective diameter when the spring is bent, and since the piston does not rotate, the spring does not twist. This has the advantage that accuracy can be improved without causing hysteresis in the timer characteristics.

[Brief explanation of the drawing]

1 and 2 show one embodiment of the present invention, FIG. 1 is a sectional view, FIG. 2 is a sectional view taken along the line - in FIG. 1, and FIG. 3 is another embodiment of the present invention. FIG. 1... Casing, 2... Fixed flange, 5...
...Piston, 6...Guide groove, 8...Stopper, 1
0...Spring, 11a, 11b...Slider, 14...Movable flange, 15...Splined cone, 16a, 16b...Helical spline portion, 17...Pump drive shaft, 29...Pressure control valve, 30... ...Hydraulic pump, 32...Microcomputer.

Claims (1)

[Claims for Utility Model Registration] (1) A hydraulically actuated piston is fitted into the casing so as to be movable in the axial direction,
A stopper protruding from the inner surface of the casing is fitted into a guide groove formed along the axial direction on the outer surface of the piston to make the piston unrotatable. springs are arranged side by side, and a slider is provided on the inner surface of the piston, which is moved in the axial direction integrally with the piston, is slidable in the circumferential direction with respect to the piston, and is rotated by a drive source. A fuel injection timing adjustment device for an internal combustion engine, characterized in that a splined cone is helically spline engaged with the inner surface of the slider, and the splined cone is connected to a pump drive shaft. (2) The fuel injection timing adjustment device for an internal combustion engine according to claim 1, wherein the oil pressure is controlled by a computer according to the operating characteristics of the internal combustion engine.