JPS6115252B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fuel injection timing adjustment device for an internal combustion engine.

[Conventional technology]

Conventionally, a fuel injection timing adjustment device uses centrifugal force to operate an eccentric cam to change the rotational phase of a rotating body connected to the engine and a shaft connected to a fuel injection pump. , for example, is known in Japanese Patent Application Laid-Open No. 54-3617.
The above device responds quickly to increases in engine rotational speed by changing the relative arrangement of the pins connected to the engine side, the pins connected to the injection pump side, and the pins connected to the weight. The injection timing can be retarded and then advanced.

To explain the above-mentioned fuel injection timing adjustment device, as shown in FIG. 1, a disk-shaped rotating body 30 is housed inside a cup-shaped rotating body 4 that rotates in synchronization with a diesel engine (not shown). A cylindrical shaft 16 integrally provided at the center of the rotating body 30 is connected to a camshaft of a fuel injection pump (not shown). A hole 30a is formed in the rotating body 30 symmetrically with respect to the shaft 16, and the first eccentric cam 5 is rotatably fitted into the hole 30a.
A second eccentric cam 15 is rotatably fitted to a. Eleven pairs of weights 14 are arranged so as to surround the shaft 16, and two guide shafts 24 are arranged at both ends of the weights 14.
are expandably connected to each other by. A spring 22 is supported at both ends of the shaft 24, which exerts a spring force that resists the centrifugal force of the weight 14. The eccentric cam 5 is supported by a pin 13 provided on the weight 14, and the eccentric cam 15 is supported by a pin 6 provided on the rotating body 4. Therefore, the driving force of the rotating body 4 is transmitted to the rotating body 30 via the pin 6, the eccentric cam 15, and the eccentric cam 5.

As shown in FIG. 2, the center O of the rotating bodies 4, 30
The central angle α between the center A of the pin 6 and the center C of the eccentric cam 5 changes as follows with respect to an increase in the rotational speed of the rotating bodies 4 and 30 in the direction of the arrow x. When the weights 14 are spread apart by centrifugal force as the engine is operated from the stopped state of the engine shown in FIG.
The center D of the pin 13 moves toward D1 in the arrow y direction about the center C of the eccentric cam 5. Along with this, the arm D-C and the arm C-B connecting the center C and the center B of the eccentric cam 15 rotate integrally around the center C, and the center A of the pin 6 is moved as shown in the figure. When moving to the left and arm C-B and arm B-A are lined up in a straight line, the central angle α becomes maximum, that is, increases by the angle θ. As the rotational speed of the engine further increases, the center A moves to the right, and the arms C-B and B-
A is bent downward, and the central angle α becomes smaller.

In this way, as the rotational speed of the engine increases, the pair of weights 14 spread out from each other against the force of the spring 22, and as shown by the solid line 40 in FIG. As L increases, a characteristic is obtained in which the injection timing is initially retarded and then advanced.

However, in such an injection timing adjustment device, in order to obtain smooth movement of the eccentric cam, it is necessary to
An appropriate gap is required at the fitting part between the hole 5a and the eccentric cam 5, and the fitting part between the hole 5a and the eccentric cam 15, the fitting part between the eccentric cam 15 and the pin 6, and the fitting part between the eccentric cam 5 and the pin 13. Appropriate gaps are also required at the joints. However, if there is such a gap, for example, when the relationship between the rotating bodies 4 and 30 is fixed in FIG.
With the play of the eccentric cams 5, 15, a range is created in which the pin 13 can move freely. That is, even if the pin 13 of the weight 14 is moved by ΔL in the radial direction as shown in FIG. 3, the angle α between the center of the pin 6 and the center of the eccentric cam 5 (FIG. 2), that is, the injection timing, will not change at all. It does not change. This causes the following problem at the inflection point on the injection timing characteristic line.

If a pair of weights 14 and springs 22 arranged symmetrically are not made to have the same weight and spring constant, one of the weights 14 will be affected by fluctuations in the rotational torque of the engine due to such non-uniformity. Start moving first. Therefore, when such a phenomenon occurs at an inflection point, the force of the weight 14 that moved first acts on the other weight 14 via the guide shaft 24, causing the weights that would normally move in opposite directions to move. 14 move in the same direction as shown by the broken line in FIG. 4, and when the amount of movement reaches a certain value, a phenomenon occurs in which they cannot move any further and become stuck.

[Problem that the invention seeks to solve]

In view of such problems, an object of the present invention is to suppress fluctuations in the rotational torque of the engine by reducing the gap between both ends of a pair of guide shafts and the inner peripheral surface of the rotating body to a predetermined value or less. This restricts the movement of a pair of weights in the same direction, so that even if one weight is pulled toward the other, it will eventually return to a position where it balances the centrifugal force, allowing it to pass through the inflection point smoothly. It is an object of the present invention to provide a fuel injection timing adjustment device.

[Means for solving problems]

In order to achieve the above object, the present invention includes a cylindrical first rotating body connected to one of an engine and a fuel injection pump, and a cylindrical first rotating body connected to the other and housed in the first rotating body. A second disc-shaped rotating body is arranged concentrically, a pair of weights are arranged sandwiching a shaft connected to the center of the second rotating body, and both ends of the pair of weights are penetrated. A spring that biases the pair of weights toward each other is supported between the ends of the pair of guide shafts and each of the weights, and is rotatably fitted inside the second rotating body. A first eccentric cam that has been rotated is supported by a pin provided on the weight, and a second eccentric cam that is rotatably fitted inside the first eccentric cam is provided on an end wall of the first rotating body. supported by a pin, and a pin provided on the weight and a pin provided on the end wall of the first rotating body are opposite to each other with respect to a line connecting the center of the first eccentric cam and the axis of the second rotating body. In a fuel injection timing adjustment device for an internal combustion engine disposed on the side and on the axis side of the second rotating body, the center of the first eccentric cam, the center of the second eccentric cam, and the first rotating body When the relative positions of the first and second rotating bodies are fixed with the centers of the pins provided on the end walls of The gap between the weight and the surface is made smaller than the play that allows the pair of weights to move toward and away from each other.

[Effect]

The amount of movement of the guide shaft 24 is limited by the gap S, which is smaller than the lift difference ΔL between the pair of weights, so even if unbalanced movement occurs between the pair of weights 14, the guide shaft 24 When the weight moves toward the radially outer weight, it collides with the inner circumferential surface of the rotating body 4, and its −
If the weight on the one side tries to move further radially outward, the spring load increases and the movement of the weight on the negative side is restricted, and the weight on the opposite side, which has a smaller spring load, lags behind. It expands and eventually reaches a state of equilibrium with the weight on the negative side. From now on, the guide shaft 24 is the rotating body 4.
The weight is separated from the inner peripheral surface of the weight and acts to balance the expansion movement of the pair of weights.

[Embodiments of the invention]

The configuration of the present invention will be explained based on an example.
As shown in FIG. 5, a cylindrical rotating body 30 connected to the engine and a disc-shaped rotating body 30 housed inside the cylinder and connected to the fuel injection pump are arranged concentrically. A pair of weights 14 are arranged sandwiching a shaft 16 that is integrally connected to the
A pin 13 is coupled to the central portion of the pin 13, and a first eccentric cam (not shown) is supported by the pin 13. It is similar to the conventional side in that it is supported by a pin 6 supported on the end wall of the body 4. A guide shaft 24 passing through the pair of weights 14 is supported at both ends thereof, a spring seat 21 supported at both ends of each guide shaft 24, and a spring seat 25 supported inside the recess 27 of the weight 14. A spring 22 is interposed between them.

According to the present invention, the end of the guide shaft 24 is preferably formed into a hemispherical shape, and the gap s between this end and the inner peripheral surface of the rotating body 4 is set as follows. That is, at the inflection point where the injection timing changes from retard to advance or vice versa in response to a change in the lift of the weight 14, that is, at the center A in FIG.
With B and C aligned in a straight line, rotating bodies 4 and 3
The length of the guide shaft 24 is determined so that the length of the guide shaft 24 is smaller than the lift ΔL by which the weight 14 can move when the weights 0 and 0 are fixed to each other.

The other configurations are the same as the conventional device shown in FIG.

In the fuel injection timing adjustment device configured as described above, as the rotational speed of the engine changes, the weights 14 spread out from each other due to centrifugal force against the force of the spring 22, and when the lift L increases, the injection timing changes. It changes along the solid line 40 shown in FIG. When one of the weights, for example the upper weight 14 in FIG. 5, moves upward first as the rotational torque changes at the inflection point,
The guide shaft 24 is arranged so that the forces of the upper and lower springs 22 are balanced.
also moves upward and attempts to pull up the lower weight 14. At this time, the eccentric cams 5, 15 and the pin 6,
When a lift difference ΔL occurs between the upper weight 14 and the lower weight 14 due to the gap between the fitting portions 13 and 13, on one weight side, arm C-B and arm B- in FIG. Although A is bent radially inward (to the axis O side), the other weight side is bent radially outward. Since the centrifugal force generated in the weight that moved radially outward first is greater, the weight that is lagging behind is attracted to the weight that is moving radially outward.

However, according to the present invention, the amount of movement of the guide shaft 24 is limited by the gap s, which is smaller than the lift difference ΔL, so even if an unbalanced movement occurs between a pair of weights, the guide shaft 24 can move freely. When the shaft 24 moves toward the upper weight located radially outward, it collides with the inner peripheral surface of the rotating body 4, and if the upper weight attempts to move further upward, the load on the upper spring 22 increases. As a result, the movement of the upper weight is restricted, and the lower weight, which has a smaller spring load, expands later, and eventually reaches a state of equilibrium with the upper weight. Thereafter, the guide shaft 24 moves away from the inner circumferential surface of the rotating body 4, as shown in FIG. 5, and serves to keep the expansion movement of both weights in balance.

〔Effect of the invention〕

Since the present invention is constructed as described above, when the pair of weights 14 move apart, that is, asymmetrically, the end of the guide shaft 24 hits the inner circumferential surface of the rotating body 4. and limit the above movements.
In other words, the lift difference between the pair of weights 14 is limited to the gap s, and since the gap s is set smaller than the dead zone ΔL of the cam mechanism, one of the weights moves in the direction of advancing the injection timing at the inflection point. However, the movement of the other weight that delays the injection timing can be eliminated, and the cam mechanism smoothly changes from retard to advance or from advance to retard in response to changes in rotational speed. can operate.

[Brief explanation of the drawing]

Fig. 1 is a front sectional view of a conventional fuel injection timing adjustment device, Fig. 2 is a diagram explaining the operation of the device, Fig. 3 is a diagram showing the characteristics of the device, and Fig. 4 is a diagram showing abnormalities of the device. FIG. 5 is a front sectional view of the fuel injection timing adjustment device according to the present invention. 4: Rotating body, 5, 15: Eccentric cam, 5a: Hole,
6, 13: pin, 14: weight, 16: shaft, 21,
25: Spring seat, 22: Spring, 24: Guide shaft, 2
7: Hole, 30: Rotating body, 30a: Hole, 40,4
1: Solid line.

Claims (1)

[Claims] 1. 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 in the first rotating body. A pair of weights are arranged concentrically and sandwiching a shaft connected to the center of the second rotating body, and an end of a pair of guide shafts passing through both ends of the pair of weights and each of the above-mentioned The weight is provided with a first eccentric cam that supports a spring that urges the pair of weights toward each other between the weights and is rotatably fitted inside the second rotating body. A second eccentric cam supported by a pin and rotatably fitted inside the first eccentric cam is supported by a pin provided on the end wall of the first rotating body, and the second eccentric cam is supported by a pin provided on the end wall of the first rotating body, and the second eccentric cam is rotatably fitted inside the first eccentric cam. A pin provided on an end wall of the first rotating body is located on opposite sides of a line connecting the center of the first eccentric cam and the axis of the second rotating body, and the axis of the second rotating body. In the fuel injection timing adjustment device of an internal combustion engine located on the side,
When the center of the first eccentric cam, the center of the second eccentric cam, and the center of the pin provided on the end wall of the first rotating body are aligned, the first and second rotating bodies are aligned with each other. An internal combustion engine in which the gap between both ends of the pair of guide shafts and the inner circumferential surface of the first rotary body is smaller than the play that allows the pair of weights to move toward and away from each other when their positions are fixed. Fuel injection timing adjustment device.