JPH0415957Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a fuel injection timing adjustment device that adjusts the injection timing of fuel supplied from a fuel injection pump according to the rotational speed of an internal combustion engine.

[Conventional technology]

This type of fuel injection timing adjustment device is also called a timer, and is known from, for example, Japanese Utility Model Application No. 56-71929.

Generally, this type of timer transmits the driving force transmitted from the internal combustion engine to the timer housing via a timer gear, and transmits the rotation of the timer housing to a second eccentric circular cam, which is housed in the housing. is transmitted to the timer weight, and the displacement of the timer weight causes the second
The circular cam and the second circular cam rotate the rotatably inserted first circular cam, and this rotation angularly displaces the timer hub relative to the housing. The camshaft of the connected injection pump is advanced or retarded to adjust the injection timing.

By the way, in the conventional timer described above, the timer gear for transmitting the driving force from the internal combustion engine to the timer housing is connected via a bolt to the end wall of the timer housing or the end plate that closes the open end of the timer housing. has been
Furthermore, the inner peripheral surface of the timer housing and the outer peripheral surface of the flange portion formed on the timer hub are configured to slide against each other.

That is, the timer housing supports the timer gear, and these timer housings are mutually rotatably supported simply by sliding contact with the flange portion of the timer hub.

[Problem that the invention attempts to solve]

According to such a sliding structure, the driving force transmitted from the internal combustion engine acts on the timer gear as a normal force, and this normal force is directly transmitted to the sliding contact surface through the timer gear housing, thereby reducing frictional resistance. growing.

In addition, when a helical gear is used as a timer gear, a thrust load is generated when the driving force is transmitted, and this thrust load is applied to the end wall of the timer housing or the end plate that closes the open end of the timer housing. A flange portion formed on the hub is brought into close contact with a large area, and this close contact generates frictional resistance between the housing and the hub.

Such frictional resistance is expressed as Np−Θ shown in Figure 3.
In the characteristics (Np is the number of rotations, Θ is the amount of angular displacement),
There was a problem that caused hysteresis when the rotation speed increased and decreased. In other words, when the rotation speed increases, Np−
The Θ characteristic becomes as shown by the solid line A, but when the rotational speed decreases, it becomes as shown by the broken line B due to the above-mentioned frictional resistance, and a large hysteresis occurs.

The occurrence of such hysteresis leads to instability of fuel injection timing, which reduces engine output, noise, and
This may cause deterioration of exhaust gas, etc.

Particularly recently, exhaust regulations based on social demands have become stricter, and direct injection engines are being used more frequently.As a result, the driving force from the engine that acts on the timer gear is increasing, which reduces the frictional resistance mentioned above. is getting bigger and bigger.

Therefore, the purpose of the present invention is to reduce the frictional resistance by preventing the normal force and thrust load generated on the timer gear from being transmitted to the sliding contact surface.
The present invention aims to provide a fuel injection timing adjustment device for an internal combustion engine that improves engine output, noise, exhaust, etc. by preventing the occurrence of hysteresis.

[Means for solving problems]

In order to achieve the above object, the present invention is characterized in that the timer gear is supported on the timer hub by a rolling bearing, and the rolling bearing is supported by a stepped portion formed on the timer hub.

[Effect]

According to such a configuration, the normal force and thrust load generated on the timer gear due to the driving force transmitted from the engine are directly supported by the timer hub,
This prevents the sliding contact surface between the timer housing and the timer hub flange from being affected.
Frictional resistance is reduced and hysteresis is reduced.

[Example of idea]

The present invention will be explained below based on a first embodiment shown in FIGS. 1 to 3.

In the figure, reference numeral 1 indicates a timer housing, which has a cylindrical shape with an end wall 2 at one end. A timer gear 3 is fixed to this end wall 2 with bolts 4. The timer gear 3 is made of a helical gear or the like, and is meshed with a drive gear on the engine side (not shown). Therefore,
The timer housing 1 is rotated in synchronization with the engine.

5 is a timer hub, which has a flange portion 6 at one end.
It also has a tapered hole 7 at the other end. A camshaft 8 of a fuel injection pump is tapered fitted into the taper hole 7, and the camshaft 8 and the timer hub 5 are connected by a round nut 9.
It is designed to rotate as one.

The flange portion 6 is slidably fitted into the interior of the timer housing 1 and comes into sliding contact with the end wall 2. Therefore, the timer housing 1 and the timer hub 5 are configured to be rotationally displaced relative to each other.

A step 10 is formed on the outer surface of the end of the timer hub 5, and a roller bearing 11 and a ball bearing 12 are fitted at positions closer to the end than the step 10. These roller bearings 11 and ball bearings 1
2 is prevented from coming off by a retaining ring 13. Therefore, the roller bearing 11 and the ball bearing 12
The step portion 10 and the retaining ring 13 prevent displacement in the axial direction. The center hole of the timer gear 3 is fitted into the roller bearing 11 and the ball bearing 12, and the timer gear 3 is connected to the timer hub 5 through the roller bearing 11 and the ball bearing 12.
is supported by

Therefore, the timer housing 1 also connects the roller bearing 11 and the ball bearing 1 through the timer gear 3.
It is supported by the timer hub 5 via 2.

Note that an oil seal 14 is provided between the end wall 2 of the timer housing 1 and the timer hub 5.

An end plate 15 is screwed to the other end of the timer housing 1 and closes the opening of the timer housing 1. A guide plate 16 is attached to the inside of this end plate 15.
An oil seal 17 is provided between the end plate 15 and the timer hub 5, and an O-ring 18 is fitted between the end plate 15 and the other end of the timer housing 1.

First circular cams 20, 20 are rotatably fitted into holes formed in symmetrical positions in the flange portion 6. These first circular cams 2
Second circular cams 21 and 21 are rotatably fitted into holes formed at eccentric positions in each of the cams 0 and 20, respectively.

First pins 22, 22 are fitted into the second circular cams 21, 21 at eccentric positions, and the protruding ends of these first pins 22, 22 are fitted into the end wall 2 of the timer housing 1. It is.

Further, second pins 23, 23 are connected to eccentric positions of the first circular cams 20, 20, and the protruding ends of these second pins 23, 23 are inserted into timer weights 24, 24. There is.

Therefore, the rotation of the timer housing 1 is
It is transmitted to the second circular cams 21, 21 via the first pins 22, 22, and the first circular cams 20,
Since the flange portion 6 is rotated through the timer hub 5 , the signal is transmitted from the timer hub 5 to the camshaft 8 .

Inside the timer housing 1, the pair of timer weights 24, 24 are arranged in a space surrounded by the flange portion 6 and the end plate 16. The timer weights 24, 24 surround the timer hub 5, and are adapted to be displaced in the radial direction due to an increase in centrifugal force due to an increase in the number of rotations.

The second pins 23, 23 connected to the eccentric positions of the first circular cams 20, 20 are inserted into these timer weights 24, 24, so that the timer weights 24, 24 increase centrifugal force. When the cams are displaced in the radial direction by
can be conveyed to.

In this case, the first circular cams 20, 20 are rotated in the direction of arrow A shown in FIG. This rotation causes the second circular cams 21, 21 to rotate in the direction of arrow B. The rotation of the second circular cams 21, 21 is transmitted to the timer housing 1 via the first pins 22, 22, and as a result, the timer housing 1 and the flange portion 6 are angularly displaced relative to each other. 1 timer hub 5
is shifted in advance.

Guide rods 25, 25 are passed through the timer weights 24, straddling the timer weights 24, 24. Each guide rod 25 has retaining rings 26 at both ends.
Spring seats 27, 27 are attached via 26, and return springs 28, 28 are provided between these spring seats 27, 27 and timer weights 24, 24.

The operation of the first embodiment with such a configuration will be explained.

The rotation of the engine is transmitted to the timer housing 1 through the timer gear 3, and the first pin 22,
22, the timer hub 5 is rotated because it is transmitted to the flange portion 6 through the second circular cams 21, 21 and the first circular cams 20, 20.

When the engine speed increases, the timer weights 24, 24 are displaced in the outer radial direction due to centrifugal force, so that the timer hub 5 is advanced relative to the timer housing 1 as described above. Therefore, the camshaft 8 of the fuel injection pump is also rotated with an advanced angle, so that the fuel injection timing is advanced.

When the engine speed decreases, the timer weights 24, 24 are pushed by the return springs 28, 28 and are displaced toward the center, thereby canceling the advance angle.

Since the timer gear 3 receiving the driving force transmitted from the engine is supported by the timer hub 5 via the roller bearing 11 and the ball bearing 12, the timer gear 3 receives the driving force transmitted from the engine in the normal direction. Even if a force is applied, this normal force is supported by the roller bearings 11 and ball bearings 12, so that it is not transmitted to the timer housing 1. That is, a large frictional force is not generated between the inner surface of the timer housing 1 and the outer surface of the flange portion 6.

Also, if timer gear 3 is a helical gear,
Thrust is generated in the timer gear 3 which receives the driving force transmitted from the engine, and the timer gear 3 is supported by a roller bearing 11.
Since displacement in the axial direction is prevented by the retaining ring 13, the thrust generated in the timer gear 3 is supported by the timer hub 5. In other words, no thrust load is applied to the end wall 2 of the timer housing 1,
Therefore, the end wall 2 and the flange portion 6 are prevented from coming into close contact with each other, and a minute gap δ is secured between them.

As a result, the frictional resistance between the timer housing 1 and the flange portion 6 is kept small, so that the hysteresis when the rotational speed rises and falls in the Np-Θ characteristic shown in FIG. 3 becomes small. In other words, when the rotational speed increases, the Np-Θ characteristic becomes as shown by the solid line A, but when the rotational speed decreases, whereas in the conventional case it becomes as shown by the broken line B, in this example, the above-mentioned frictional resistance Since this has been reduced, hysteresis occurs less than in the past, as shown by the broken line C.

4 to 6 show a second embodiment of the present invention, in which the fuel injection timing is advanced at low temperature start, and the components are the same as those of the first embodiment. are given the same number and their explanation will be omitted.

The timer gear 3 of this embodiment uses a spur gear, and therefore has two ball bearings 1 as bearings.
2,12 are used.

Moreover, shape memory alloy springs 30, 30 are stretched between the spring receiver seat 27 and the timer weights 24, 24, on the guide rod 25 inserted between the timer weights 24, 24. The shape memory alloy springs 30, 30 are set to shorten at a low temperature of, for example, 5°C or lower, and to expand at a high temperature of over 5°C.

Further, inner spring seats 31, 31 are attached to the center of the guide rod 25, and between the inner spring seats 31, 31 and the spring seats 27, 27, main return springs 32, 32 are installed. is being passed over.

Furthermore, center spring seats 34, 34 are slidably attached to the center of the guide rod 25, and these center spring seats 34, 34 are moved toward and away from the timer weights 24, 24. In addition, these central spring seats 34, 3
A bias spring 35 is provided between the two.

According to such a configuration, at high ambient temperatures exceeding 5° C., the shape memory alloy springs 30, 30
has been extended, and the timer waits 24, 24
is pressed in the center. In this state, since the timer weights 24, 24 are located on the center side, the injection timing is on the retarded side, and therefore, when the engine is started, it changes along the characteristic D shown in FIG.

On the other hand, when the ambient temperature is less than 5℃,
Since the shape memory alloy springs 30, 30 are shortened, the force pushing the timer weights 24, 24 toward the center by the shape memory alloy springs 30, 30 is zero or small, and therefore the timer weights 24, 24 is pushed by the bias spring 35,
Displaced in the outer diameter direction. timer weight 2
4 and 24 are displaced outward, the injection timing is shifted to the advanced side. Therefore, if the engine is started in this state, the engine will start in an advanced state as shown by characteristic E in Fig. 6. will be done.

Therefore, according to this invention, the injection timing is advanced at the time of low-temperature starting, which improves starting performance and improves odor and smoke exhaust.

In the fuel injection timing adjustment device of the second embodiment having such characteristics, the timer gear 3 is connected to the ball bearing 1.
Since the timer hub 5 is supported by the timer hub 5 through the timer gears 2 and 12, even if a normal force is applied to the timer gear 3 due to the driving force transmitted from the engine, this normal force is supported by the ball bearings 12 and 12. In addition, even if thrust is generated in the timer gear 3, the ball bearing 12 is prevented from being displaced in the axial direction by the stepped portion 10, so the thrust generated in the timer gear 3 is supported by the timer hub 5. That is, no force is applied to the timer housing 1 from the engine side, and no force is transmitted to the timer housing 1. Therefore, a large frictional force is not generated between the inner surface of the timer housing 1 and the outer surface of the flange portion 6.

As a result, the frictional resistance between the timer housing 1 and the flange portion 6 is kept small, so that the hysteresis when the rotational speed increases and decreases in the Np-Θ characteristic shown in FIG. 6 becomes small. In other words, when the rotational speed increases, the Np-Θ characteristic becomes as shown by the solid line H, but when the rotational speed decreases, the frictional resistance is reduced, so it becomes as shown by the broken line H, which is compared to the conventional characteristic H. The occurrence of hysteresis is reduced.

Particularly, the reduction of hysteresis in the N1 region in FIG. 6 is highly effective.

[Effect of idea]

As explained above, according to the present invention, the normal force and thrust load generated on the timer gear due to the driving force transmitted from the engine are directly supported by the timer hub using rolling bearings, and the flange portion of the housing and the hub are supported directly by the timer hub. Since no action is applied to the sliding contact surface, frictional resistance is reduced and hysteresis is reduced. Therefore, variations in the advance angle characteristics are reduced, so that the engine output, noise, exhaust, etc. can be maintained at good constant values even when the engine speed increases or decreases.

[Brief explanation of the drawing]

1 to 3 show a first embodiment of the present invention, and FIG. 1 is a cross-sectional view taken along the - line in FIG.
The figure is a sectional view taken along the - line in Figure 1, and Figure 3 is a cross-sectional view taken along the - line in Figure 1.
Θ characteristic diagrams, FIGS. 4 to 6 show a second embodiment of the present invention, FIG. 4 is a sectional view taken along the line - in FIG. 5, and FIG. 5 is a sectional view taken along the line - in FIG. 4. , FIG. 6 is a Np-Θ characteristic diagram. 1... Timer housing, 3... Timer gear, 5... Timer hub, 6... Flange section, 8
...Camshaft, 10...Step part, 11...Roller bearing,
12...Ball bearing, 20...First circular cam, 21
...Second circular cam, 22...First pin, 23
...Second pin, 24...Timer wait, 3
0...Shape memory alloy spring.

Claims (1)

[Claims for Utility Model Registration] A timer gear that is rotated by receiving driving force from an internal combustion engine, a timer housing that is connected to the timer gear and rotated by the timer gear, and a flange portion that is housed in the timer housing. a timer hub connected to the camshaft of the injection pump; a timer weight housed in the timer housing and displaced by centrifugal force;
A first circular cam rotatably inserted into the flange portion, and a second circular cam rotatably inserted into the first circular cam and rotated by centrifugal displacement of the timer weight. A fuel injection timing adjustment device for an internal combustion engine, which rotates the two circular cams by centrifugal displacement of the timer weight to rotate the timer housing and the timer hub relative to each other; An internal combustion engine characterized in that a rolling bearing is fitted, a timer gear is rotatably supported by the rolling bearing, and one axial end of the rolling bearing is supported by a step formed on the outer peripheral surface of the timer hub. Fuel injection timing adjustment device.