JP2762588B2 - Fuel injection timing adjustment device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an eccentric cam type fuel injection timing adjusting device used for fuel injection of an internal combustion engine.

(Prior art)

Fuel supply to internal combustion engines has been
The direct injection type is frequently used.

The fuel injection pump used for the direct injection fuel injection needs to supply atomized fuel in a short time. Therefore, the fuel injection pump has a large plunger diameter. Therefore, a fuel injection timing adjustment device (hereinafter also referred to as an adjustment device) directly connected to the fuel injection pump is:
Large driving torque is required.

However, in recent years, as the torque in the fuel injection has increased as described above, the characteristics of the fuel injection timing adjustment device have become unstable, so that the eccentricity has been replaced by the swing type adjustment device used previously. Cam type adjusting devices are frequently used.

Such an eccentric cam type adjusting device is described in, for example,
There is one disclosed in JP-A-133314.

As shown in FIGS. 9 and 10, the adjusting device has a flange portion 901 and a fuel injection pump (not shown).
A hub 90 connected to the cam shaft 65, a case 92 and a cover 91 surrounding the outer periphery of the hub 90 and the flange portion 901 and a space 2 formed in the space formed by the hub 90, the case 92, and the cover 91. Weights 93,93. The flange portion 901 is provided with a large eccentric cam 94 rotatably inserted and a small cam 95 rotatably inserted into the large cam 94.

Further, a groove 902 is formed on the outer periphery of the flange portion 901,
On the inner peripheral side of the case 92, a projection 921 to be housed in the groove is formed, and a bolt 911 for connecting the case 92 and the cover 91 is screwed into the projection 921. Large cam above
Two combinations of 94 and small cam 95 are provided. The eccentric shaft pin 941 of the large cam 94 is connected to the weight 93, and the small cam 9
The fifth eccentric shaft pin 951 is connected to the cover 91.

The weight 93 is, as shown in FIG.
The upper and lower sheets 96 inserted in the sheet guide 96
Between 1,962, a spring-shaped timer spring 97 facing the centrifugal force of the weight 93 is arranged. Above seat guide 96
Are provided on the two weights 93, 93 at two locations on the left and right, respectively.

In this adjusting device, the rotation of the internal combustion engine is transmitted to the case 92 and the cover 91 via gears and the like. When these rotation speeds increase, a centrifugal force is generated in the weights disposed therein, and the weights 93 expand,
The large cam 94 rotates. The small cam 95 is linked with it,
The “case 92 and cover 91” and the “hub 90” are relatively rotated and displaced, and the fuel injection timing is adjusted.

[Problem to be solved]

However, in recent years, from the viewpoint of speeding up the internal combustion engine and improving the accuracy of the fuel supply timing of the fuel injection pump,
It is strongly desired to improve the timer characteristics of the adjusting device, that is, the control power of the adjusting device.

Therefore, the present inventors have repeated various studies on the control force of the adjusting device with respect to the eccentric cam type adjusting device.
The focus was on increasing the centrifugal force of the weight. In order to increase the centrifugal force, the configuration of the entire adjusting device was examined.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and an object thereof is to provide a fuel injection timing adjusting device capable of increasing a centrifugal force of a weight and improving a control force.

[Solutions to solve the problem]

According to the present invention, the weight is expanded in conjunction with the rotation of the internal combustion engine, and the eccentric large and small cams are rotated accordingly, and the rotation is transmitted to the cam shaft of the fuel injection pump.
An eccentric cam type fuel injection timing adjusting device for adjusting the fuel injection timing of a fuel injection pump according to the rotation speed of an internal combustion engine, comprising a disk-shaped cam plate disposed on a plane parallel to the rotation direction. A driving flange having a U-shaped cross section passing through the center of rotation of the cam plate and perpendicular to the rotation direction, and facing the cam plate so as to cover the opening of the driving flange. A substantially flat side cover arranged, a space formed by integrally fixing the driving flange and the side cover so as to be rotatable, and a transmission of the rotation of the internal combustion engine connected to the driving flange or the side cover. A pair of weights are arranged in the space, and the pair of weights rotate the side cover. In the diametric direction passing through the core, the rear faces are arranged facing each other. On the other hand, the flange for the driven side is arranged on the cam plate in an unfixed state, and the cam shaft is fixed to the flange. In addition, two eccentric large cams are rotatably fitted to the cam plate of the driving flange, and each eccentric small cam is rotatably fitted to each large cam. In addition, a weight pin is connected to each eccentric shaft hole of each large cam and each of the above weights, while a flange pin is connected to each eccentric shaft hole of each small cam and each of the flanges. In the fuel injection timing adjusting device.

The most remarkable point of the present invention is that the weight is arranged in the space surrounded by the side cover and the driving flange without disposing the hub shown in the prior art. The rotation of the cam is transmitted to the cam shaft via a flange pin and a flange.

In other words, the weight does not have a hub near the center thereof, and the radius of the weight is increased.

The rotation of the internal combustion engine is transmitted to the driving flange by providing a gear, a coupling with a laminate, a pawl, and the like (see the first to third embodiments).

The combination of the large cam and the small cam is two as in the above-described conventional technology.

[Action]

In the adjusting device according to the present invention, the cam plate and the side cover of the driving flange on the driving side are integrally rotated with the rotation of the internal combustion engine, for example, via the gear of the driving side cover, and the space between them is formed in the space therebetween. The arranged weight rotates.

Then, as the rotation speed increases, the weight expands (moves) in the radial direction due to centrifugal force. Therefore, the large eccentric cam connected to the weight via the weight pin is rotated, and accordingly, the small eccentric cam rotatably disposed in the large cam is rotated. Therefore, the driven-side flange connected to the small cam via the flange pin rotates. Then, the driven flange rotates the camshaft of the fuel injection pump connected thereto.

At this time, between the driving-side driving flange and the driven-side flange, a phase difference (Δ
θ). However, since the flange and the camshaft of the fuel injection pump are fixed to each other, the camshaft is advanced.

On the other hand, when the rotation speed of the internal combustion engine decreases, the centrifugal force of the weight decreases, the rotation of the large cam and the small cam decreases, and the advance angle of the cam shaft also decreases.

Thus, in the present invention, a hub is not provided in the vicinity of the center of the weight as in the prior art. Therefore, the inner radius of the weight can be reduced by the length (radius) of the portion where the hub does not exist. Therefore, the diameter of the weight can be made larger than before, and the weight of the weight can be made larger.

Therefore, the centrifugal force (F) of the weight, which is a major factor of the timer control force (M) representing the capability of the adjusting device, can be increased. That is, F = K · r _G · N _P ² · W (where K is a constant, r _G is the distance between the position of the center of gravity of the weight and the rotation center, N _P is the number of shaft rotations, and W is the weight of the weight) W in the equation can be increased.

Conventionally, the size of the diameter of the large cam is limited due to the presence of the hub, but in the present invention, the degree of freedom in designing the large cam is increased by the absence of the hub. That is, 2
The size between the axes of the two large cams can be arbitrarily set. Therefore, as shown in FIG. 8, the advance angle (θ) with respect to the stroke (St) of the large cam increases, and the advance angle characteristic of the timer characteristic can be greatly increased (for example, when the outer diameter is the same). , Twice as much as before).

Further, the distance between the sheet guides of the weight (the length L in FIG. 2) can be approached by the amount of eliminating the hub. For this reason, the mounting space for the timer spring is enlarged, and the design can be easily coped with the weight increase of the weight.

〔effect〕

As described above, according to the present invention, the centrifugal force of the weight can be increased, and the degree of freedom in designing a large cam can be increased.

Therefore, it is possible to provide a fuel injection timing adjusting device that is excellent in control power representing the expansion of the advance angle range of the timer characteristic and the timer capability.

Therefore, the adjusting device of the present invention exhibits excellent performance for a high-pressure fuel injection pump effective for exhaust NOx countermeasures. Therefore, it is possible to prevent white smoke at the time of starting the internal combustion engine (in the fourth embodiment), and to increase horsepower from a large advance angle characteristic at the time of high-speed operation of the internal combustion engine.

〔Example〕

First Embodiment A fuel injection timing adjusting device according to an embodiment of the present invention will be described with reference to FIGS.

As shown in FIGS. 1 to 3, the apparatus of this embodiment has a disk-shaped cam plate 15 disposed inside on a surface parallel to the rotational direction.
0 and the cam plate 150
A driving flange 15 having a U-shaped cross section passing through the center of rotation of the driving flange 15 and a pair of weights 5, 5 provided in the driving flange 15, and an opening of the driving flange 15 (right side in FIG. 1) ) Is provided so as to cover the cam plate 150 and the substantially flat side cover 1 disposed facing the cam plate 150. Further, the drive-side cover 7 adjacent to the cam plate 150, a driven-side flange 62 rotatably fitted around the axis of the drive-side cover 7, and a cam coupled to the axis of the flange 62. It consists of an axis 65. The camshaft 65
Is connected to a fuel injection pump (not shown).

As shown in FIGS. 1 to 3, the pair of weights 5, 5 are arranged with their back surfaces facing each other in the diameter direction passing through the center of rotation of the side cover 1 (the same applies to the driving flange 15). .

Further, as shown in FIG. 1, the side cover 1 and the drive side cover 7 are integrally rotatably connected by a driving flange 15.

As shown in FIGS. 1 and 3, the eccentric large cam 3 is rotatably fitted to the cam plate 150 of the driving flange 15, and the eccentric small cam 3 is further fitted to the large cam 3. The cam 4 is rotatably fitted. In addition, weight 5
, The weight pin and the eccentric shaft hole of the large cam 3 are rotatably fitted, and the flange pin 61 is connected between the flange pin 62 and the weight pin 51 and the eccentric shaft hole of the small cam 4. Are rotatably fitted.

A gear 72 for transmitting the rotation of the internal combustion engine via an engine idler gear (not shown) is provided on the outer periphery of the drive side cover 7. The side cover 1 is fixed to the driving flange 15 by bolts 12 and the drive side cover 7 is fixed to the driving flange 15 by bolts 71. The flange 62 is rotatably fitted to the drive side cover 7 via an oil seal 74.

In addition, the center of rotation of the flange 62 is
The end of the camshaft 65 is screwed and connected.

Further, as shown in FIG. 1, the weight 5 is held by a sheet guide 55 provided in a recess 50 as in the prior art. Between the upper and lower sheets 57 and 58 inserted into the sheet guide 55, timer springs 561 and 562 facing the centrifugal force of the weight 5 are arranged. The upper end of sheet 57
It is locked to the seat guide 55 by a retaining ring 551. The sheet guides 55 and the like are provided at two positions on the weights 5 and 5, respectively (FIG. 2).

As shown in FIGS. 1 and 3, a circular hole 151 is provided in the cam plate 150 of the driving flange 15, and the large cam 3 is rotatably fitted in the circular hole 151. A weight pin 51 is provided between the eccentric shaft hole 301 of the large cam 3 and the weight 5.
Are slidably fitted. Also, a circular hole 31 provided in the large cam 3
, The small cam 4 is rotatably fitted. A flange pin 61 is slidably fitted between the eccentric shaft hole 401 of the small cam 4 and the flange 62.

Further, the inner diameter D2 of the spigot 156 of the driving flange 15 to which the side cover 1 is fitted (FIG. 1) and the spigot 15 of the driving flange 15 to which the driving side cover 7 is fitted.
The relationship between 5 and the inner diameter D3 (FIGS. 1 and 3) is D2 ≦ D3. Further, half of the difference between the major diameter D1 between the large cams shown in FIG. 3 and D3, that is, the interval t is 0.3 to 0.5 mm. There is an interval L between the weight sheet guides 55.

 Next, the function and effect will be described.

First, the rotational force from the internal combustion engine is transmitted to the gear 72 via an engine idler gear (not shown). Thus, the drive side cover 7, the driving flange 15, the cam plate 150, and the side cover 1 rotate. Then, as the rotational speed of the internal combustion engine increases, that is, as the rotational speed of the driving flange 15 increases, the weight 5 moves in the radial direction due to centrifugal force against the urging force of the timer springs 561 and 562.

Therefore, the weight pin 51 rotates the large cam 3 in the direction of the arrow in FIG. Accordingly, the small cam 4 also rotates in the direction of the arrow. Then, the small cam 4 rotates the flange 62 via the flange pin 61.

At this time, the side cover 1 and the driven side flange
A phase difference (Δθ) occurs in the rotation direction between the rotation direction and the rotation direction.
However, the flange 62 and the camshaft 65 of the fuel injection pump
Is fixed by the nut 60, so that the cam shaft is advanced.

On the other hand, when the rotation speed of the internal combustion engine decreases, the centrifugal force of the weight 5 decreases, and the timer springs 561 and 56 oppose this.
The set load of 2 causes the large cam 3 and the small cam 4 to rotate in the opposite direction. Therefore, the advance angle of the cam shaft 65 is reduced.

Thus, in the adjusting device of this example, the side cover 1
The weights 5, 5 are arranged in a space surrounded by the driving flange 15 and the driving flange 15. The hub (reference numeral 90 in FIGS. 9 and 10) shown in the prior art does not exist near the center of the weights 5,5. Therefore, the weight (shape) of the weight can be increased only in the space where the hub was located.

Therefore, the centrifugal force of the weight, which is a major factor of the timer control force and represents the performance of the adjusting device, can be increased. Therefore, an adjusting device excellent in timer control power can be obtained.

Further, in the related art, the size and arrangement position of the large cam 3 are limited due to the presence of the hub. However, the adjustment device of this example does not have such a limitation. Therefore, the degree of freedom in designing a large cam is expanded, and the advance angle characteristic, which is a timer characteristic, can be increased as compared with the conventional case. Therefore, according to the present invention, as shown in FIG.
Can be made larger than before.

For example, when the outer diameter of the adjusting device (the outer diameter of the driving flange 15) is 165 mm, an advance angle approximately twice as large as that of a conventional adjusting device can be obtained. That is, in the present embodiment, the degree of freedom of the diameter of the large cam and the small cam can be 40% or more, so that the size between the fulcrums of both cams can be increased in proportion to this. Therefore, the advance angle (θ) with respect to the weight stroke (St) can be increased (see FIG. 8).

Second Embodiment In this embodiment, as shown in FIG. 5, in the adjusting device of the first embodiment, a means for transmitting the rotation of the internal combustion engine is provided by a gear 72.
Is replaced by a coupling 115 with a laminate. The coupling 115 is provided in the screw hole 1 of the side cover 1.
02 is fixed with bolts 116.

The laminated coupling 115 is formed by laminating thin steel plates. When a misalignment occurs between the drive shaft of the internal combustion engine and the cam shaft of the fuel injection pump,
This misalignment can be adjusted while transmitting power.

In addition, when the driving torque fluctuates greatly due to the increase in the pressure of the fuel injection pump, the coupling 115 can absorb the fluctuation torque to the adjusting device. Therefore, variations in the injection timing are reduced, and the characteristics of the internal combustion engine are also stabilized.

 Further, the same operation and effect as those of the first embodiment can be obtained.

Third Embodiment In this embodiment, as shown in FIG. 6, a claw is attached to the side cover 1 instead of the gear 72 in the adjustment device of the first embodiment.
11,11 are provided. The claws 11, 11 are connected to a rotation transmission unit (not shown) of the internal combustion engine via an Oldham coupling (not shown).

In this embodiment, the same effect as in the first embodiment can be obtained.

Fourth Embodiment In this embodiment, the setting position of the flange pin 61 of the small cam 4 is changed in the first embodiment.

That is, in FIG. 3, in the first embodiment, the flange pin 61 is located closer to the weight pin 51 of the large cam as shown in FIG. However, in this example, the position of the flange pin 61 is provided on the side far from the weight pin 51, that is, on the outside in FIG.

According to such a configuration, as shown in FIG. 7, it is also possible to obtain a timer characteristic of the starting advance angle (RETARD). Since there is no equivalent to the hub in the prior art, as described in the first embodiment, compared to the prior art,
The start angle and the normal time advance angle can be made large.

 Further, the same effects as in the first embodiment can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 to 4 show a fuel injection timing adjusting device according to a first embodiment, FIG. 1 is a sectional view taken along the line Y--Y in FIG. 3, and FIG. 1 is a sectional view taken along line AA of FIG. 1, and FIG. 3 is a sectional view taken along line BB of FIG.
FIG. 4 is a diagram showing the relationship between the rotational speed of the internal combustion engine and the advance angle of the camshaft, FIG. 5 is a diagram of the second embodiment, and FIG. 7 is a diagram showing the relationship between the rotational speed of the internal combustion engine and the advance angle of the camshaft in the fourth embodiment, FIG. 8 is a diagram illustrating the effect of the present invention,
9 and 10 show a conventional fuel injection timing adjusting device, FIG. 9 is a sectional view thereof, and FIG. 10 is a sectional view taken along line CC of FIG. 1 ... side cover, 15 ... driving flange, 150
... Cam plate, 3 ... Large cam, 4 ... Small cam, 5 ... Weight, 51 ... Weight pin, 55 ... Sheet guide, 61 ...
… Flange pin, 62 …… Flange, 65 …… Cam shaft, 7 …… Drive side cover,

Claims (1)

(57) [Claims] The weight is expanded in conjunction with the rotation of the internal combustion engine, and the eccentric large and small cams are rotated accordingly, and the rotation is transmitted to the cam shaft of the fuel injection pump.
An eccentric cam type fuel injection timing adjusting device for adjusting the fuel injection timing of a fuel injection pump according to the rotation speed of an internal combustion engine, comprising a disk-shaped cam plate disposed on a plane parallel to the rotation direction. A driving flange having a U-shaped cross section passing through the center of rotation of the cam plate and perpendicular to the direction of rotation, and facing the cam plate so as to cover the opening of the driving flange. A substantially flat side cover disposed, a space formed by fixing the driving flange and the side cover so as to be integrally rotatable, and a transmission of the rotation of the internal combustion engine connected to the driving flange or the side cover. A pair of weights are arranged in the space, and the pair of weights rotate the side cover. In the diametric direction passing through the center, the back faces are arranged facing each other. On the other hand, the flange on the driven side is arranged on the cam plate in an unfixed state, and the cam shaft is fixed to the flange. The cam plate of the driving flange has 2
The two eccentric large cams are rotatably fitted, and the eccentric small cams are rotatably fitted to each large cam.
Weight pins are connected to the eccentric shaft holes of each large cam and the above weights, while flange pins are connected to the eccentric shaft holes of each small cam and the flanges. Fuel injection timing adjustment device.