JP2503394B2 - Fuel injection timing adjustment device for internal combustion engine - Google Patents

Description

Description: TECHNICAL 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 adjusting device is also called a timer and is known from, for example, Japanese Utility Model Laid-Open No. 56-71929.

Generally, this type of timer rotates a timer housing by a driving force transmitted from an internal combustion engine, transmits this rotation to a second eccentric circular cam, and also transmits it to a centrifugal weight housed in the timer housing, thereby Due to the displacement of the weight, the second circular cam and the first circular cam into which the second circular cam is rotatably inserted are rotated, and by this rotation, the timer hub is relatively angled with respect to the housing. The camshaft of the injection pump connected to this timer hub is displaced and advanced or retarded to adjust the injection timing.

By the way, the Np-.THETA. Characteristic (Np is the number of revolutions, .THETA. Is the amount of angular displacement) of the conventional timer is set as shown by the solid line B in FIG.

[Problems to be solved by the invention]

However, in recent diesel engines, it is desired to improve startability in cold regions and improve odor and smoke emission at the time of starting.

For this purpose, it is required to advance the fuel injection timing at the time of start-up in a cold region and to have the characteristic shown by the mouth in the Np-Θ characteristic of FIG.

Therefore, an object of the present invention is to provide a fuel injection timing adjusting device for an internal combustion engine, which can advance the fuel injection timing at the time of starting in a cold region to improve startability and improve odor and smoke. It is a thing.

[Means for solving problems]

In order to achieve the above object, the present invention provides a timer housing to which a driving force is applied from an internal combustion engine, and a pair of centrifugal weights housed in the timer housing and moving toward and away from each other in a radial direction according to rotation. Guide rod for guiding the radial movement of the centrifugal weight, the end spring seat attached to the end of the guide rod, and the centrifugal weight attached slidably in the middle of the guide rod. The centrifugal weight is provided between the inner spring seat that is pressed and moved by the centrifugal weight when it moves in the outer diameter direction by a predetermined distance or more, and the centrifugal weight is provided inside the inner spring seat. A main spring that presses and urges these centrifugal weights toward each other when they come into contact with a spring seat and a centrifugal way provided between the end spring seat and the centrifugal weight. Shape memory alloy spring that expands and contracts along the moving direction of the grate and reduces the initial load when the temperature falls below a predetermined temperature, and a bias spring that reduces the acting force of the shape memory alloy spring above the predetermined temperature. A timer hub having a flange portion and connected to the cam shaft of the injection pump; a pair of first circular cams rotatably inserted into the eccentric position of the flange portion; and eccentric positions of these first circular cams. And a pair of second circular cams connected to the centrifugal weight through a second pin and rotatably inserted into each of the second circular cams. .

[Action]

According to such a configuration, in a low temperature state below a predetermined temperature, the initial load of the shape memory alloy spring decreases, so that the centrifugal weight is pushed by the bias spring and moves in the outer diameter direction, that is, to the advance side. Since it is displaced, the fuel injection timing can be advanced at the time of starting in a low temperature atmosphere.

In the low rotation range, the centrifugal weight does not contact the inner spring seat and the acting force of the main spring does not act on the centrifugal weight. The load on the alloy spring can be reduced. Moreover, since the centrifugal weight is pressed by the spring force of the shape memory alloy spring and the spring force of the bias spring in this low rotation range, the centrifugal weight does not wobble.

Further, since the shape memory alloy spring expands and contracts along the moving direction of the centrifugal weight, the acting force of the shape memory alloy spring can be linearly transmitted to the centrifugal weight, and the transmission efficiency is good and the shape memory alloy spring The load can be set small and the control efficiency of the centrifugal weight can be increased.

Example of Invention

The present invention will be described below based on an embodiment shown in FIGS. 1 to 5.

In the drawing, reference numeral 1 denotes a timer housing, which has a tubular shape having an end wall 2 at one end. A timer gear 3 is fixed to the end wall 2 with a bolt 4, and the timer gear 3 meshes with a drive gear (not shown) on the engine side. Therefore, the timer housing 1 is rotated in synchronization with the engine.

A timer hub 5 has a flange portion 6 at one end and a tapered hole 7 at the other end. A cam shaft 8 of the fuel injection pump is taper-fitted into the tapered hole 7, and the cam shaft 8 and the timer hub 5 are round nuts 9.
It is connected by and can rotate integrally.

The flange portion 6 is slidably fitted inside the timer housing 1 and slidably contacts the end wall 2. Therefore, the timer housing 1 and the timer hub 5 are relatively rotationally displaced.

An oil seal 10 is provided between the end wall 2 of the timer housing 1 and the timer hub 5.

An end plate 11 is screwed into the other end of the timer housing 1 to close the opening of the timer housing 1. A guide plate 12 is attached to the inside of the end plate 11. An oil seal 13 is provided between the end plate 11 and the timer hub 5, and an O-ring 14 is provided between the end plate 11 and the other end of the timer housing 1.
Is inserted.

First circular cams 15 and 15 are rotatably fitted in the flange portion 6 in holes formed at symmetrical positions. Second circular cams 16 and 16 are rotatably fitted in holes formed at eccentric positions in the first circular cams 15 and 15, respectively.

The second circular cams 16 and 16 have the first pin 1 at the eccentric position.
7, 17 are fitted together, and the projecting ends of these first pins 17, 17 are fitted into the end wall 2 of the timer housing 1.

Further, the second pins 18, 18 are connected to the eccentric positions of the first circular cams 15, 15, and the projecting ends of these second pins 18, 18 penetrate centrifugal weights 19, 19 described later. The bush 21 in the guide hole 20 formed in the guide plate 12.
It is slidably inserted through. The guide hole 20
Has an elongated hole so as not to restrain the range in which the second pins 18, 18 are moved by the rotation of the first circular cams 15, 15.

Therefore, the rotation of the timer housing 1 depends on the first
Is transmitted to the second circular cams 16,16 via the pins 17,17 of
Since the flange portion 6 is rotated through the first circular cams 15, 15, it is transmitted from the timer hub 5 to the cam shaft 8.

Inside the timer housing 1, a pair of centrifugal weights 19, 19 are arranged in a space surrounded by the flange portion 6 and the other end plate 11. The centrifugal weights 19 and 19 surround the timer hub 5 and are displaced in the radial direction due to an increase in centrifugal force due to an increase in rotation speed. In this case, the pair of centrifugal weights 19 and 19 linearly move in a direction in which they come into contact with and separate from each other while maintaining a substantially parallel state.

The second pins 18 and 18 connected to the eccentric positions of the first circular cams 15 and 15 penetrate through these centrifugal weights 19 and 19, so that the centrifugal weights 19 and 19 are increased in diameter due to an increase in centrifugal force. When displaced in the direction, this displacement causes the second pin 18,18
Through the first circular cam 15,15.

In this case, the first circular cams 15, 15 are rotated in the direction of arrow A shown in FIG. By this rotation, the second circular cams 16, 16 are rotated in the direction of arrow B. The rotation of the second circular cams 16, 16 is transmitted to the timer housing 1 via the first pins 17, 17, and as a result, the timer housing 1 and the flange portion 6 are relatively angularly displaced, so that the timer housing 1 is rotated. In contrast, the timer hub 5 is advanced and displaced.

Guide rod 2 straddling the centrifugal weights 19 and 19
3,23 are penetrated. Each guide rod 23 is a stepped rod having a large diameter over a predetermined length of the central portion, and end spring seats 25, 25 are attached to both ends via retaining rings 24, 24. . Shape memory alloy springs 26, 26 are stretched between the end spring seats 25, 25 and the centrifugal weights 19, 19. The shape memory alloy springs 26, 26 are set to shorten in a low temperature state of, for example, 5 ° C. or lower, and to expand in a high temperature of more than 5 ° C.

Further, inner spring seats 27, 27 are attached to the central portion of the guide rod 23 by being stopped by the step portion having the larger diameter, and the inner spring seats 27, 27 and the end spring seat 25 are attached. ,
Main springs 28 and 29 are stretched between 25.

Further, central spring seats 30 and 30 are slidably attached to the central part where the diameter of the guide rod 23 increases, and these central spring seats 30 and 30 are attached by snap rings 31 and 31. The sliding range is regulated. The central spring seats 30 and 30 are adapted to come into contact with and separate from the centrifugal weights 19 and 19, and the central spring seats 3 and
A bias spring 32 is provided between 0 and 30. The bias spring 32 pushes the centrifugal weights 19, 19 in the outer diameter direction, and when the shape memory alloy springs 26, 26 are extended and push the centrifugal weights 19, 19 toward the center side, they resist the force. The spring forces act to cancel each other out.

The operation of the embodiment having such a configuration will be described.

At a high ambient temperature of more than 5 ° C, the shape memory alloy springs 26, 26 are stretched, and the centrifugal weights 19, 19 are pushed toward the center side with a large force.
Is in the position shown in FIG. 2, and the bias spring 32 is compressed. In this state, since the centrifugal weights 19 and 19 are located on the center side, the injection timing is on the retard side, so that when the engine is started, the injection timing changes along the characteristic a in FIG.

On the other hand, when the ambient temperature is less than 5 ° C., the shape memory alloy springs 26, 26 are shortened, so the force pushing the centrifugal weights 19, 19 toward the center side by the shape memory alloy springs 26, 26 is Since it is zero or small, the centrifugal weights 19 and 19 are pushed by the bias spring 32 and displaced in the outer radial direction as shown in FIG. Centrifugal weight 19,19
When the engine is displaced outward, the injection timing is shifted to the advance side. Therefore, when the engine is started in this state, the engine is started in the advanced state as shown by the characteristic B in FIG. .

When the number of rotations increases, the centrifugal weights 19, 19 are displaced in the radial direction by the increase in centrifugal force, and as described above, this displacement is caused by the first circular cams 15, 15 through the second pins 18, 18. The first circular cams 15 and 15 are rotated in the direction of arrow A shown in FIG. By this rotation, the second circular cams 16, 16 are rotated in the direction of arrow B. The rotation of the second circular cams 16, 16 is transmitted to the timer housing 1 via the first pins 17, 17, and as a result, the timer housing 1 and the flange portion 6 are relatively angularly displaced, so that the timer housing 1 is rotated. In contrast, the timer hub 5 is advanced and displaced.

In this state, as shown in Fig. 4, the centrifugal weight 1
Shape memory alloy spring 2 due to radial displacement of 9,19
6 and 26 are compressed, and inner spring seats 27 and 27 are pressed outward to compress main springs 28 and 29.

Therefore, in both cases of low temperature starting and room temperature starting, the Np-Θ characteristic follows the same locus when the rotation speed increases.

When the number of rotations decreases, the centrifugal weights 19, 19 are urged by the urging forces of the shape memory alloy springs 26, 26 and the main springs 28, 29.
Is moved to the center side, whereby the injection timing is returned to the retard side.

When restarting after the engine is stopped and the ambient temperature is high, the shape memory alloy springs 26, 26 are stretched, so the state shown in FIG. 2, that is, Np-
It exhibits a Θ characteristic.

Therefore, according to this, since the injection timing is advanced at the low temperature start, the startability is improved, and the odor and smoke can be improved.

Further, since the shape memory alloy springs 26, 26 and the bias spring 32 are provided so as to face each other, the centrifugal weights 19, 19 may fluctuate in the region at the beginning of the advance angle when the rotational speed increases in the characteristic shown in FIG. There is also an advantage of preventing the generation of impact sound and destabilization of characteristics.

Moreover, the shape memory alloy springs 26, 26 are the centrifugal weights 19, 19.
Since it is arranged so as to expand and contract along the moving direction of, the acting force of the shape memory alloy springs 26, 26 can be linearly transmitted to the centrifugal weights 19, 19, so that the transmission efficiency is good and therefore small. The centrifugal weights 19 and 19 can be controlled even with the load.

Further, since the centrifugal weights 19, 19 do not contact the inner spring seats 27, 27 and the acting force of the main springs 28, 29 does not act on the centrifugal weights 19, 19 in the low rotation range, the shape memory alloy The springs 26,26 are not subject to the resistance of the main springs 28,29.
The load on the shape memory alloy springs 26, 26 can be reduced.

〔The invention's effect〕

As described above, according to the present invention, when the temperature is lower than a predetermined temperature, the temperature-sensing actuating elastic member displaces the centrifugal weight toward the advance side, so that the fuel injection timing can be advanced at the low temperature start. The startability is improved, and the odor and smoke can be reduced. Further, since the shape memory alloy spring does not receive the resistance of the main spring at the time of starting, the load of the shape memory alloy spring can be reduced, and moreover,
Since the bias spring holds down the centrifugal weight in this low rotation range, the centrifugal weight does not sway.

Further, since the shape memory alloy spring expands and contracts along the moving direction of the centrifugal weight, the acting force of the shape memory alloy spring can be linearly transmitted to the centrifugal weight, the transmission efficiency is good, and the shape memory alloy spring is The load of can be set small, and the control efficiency of the centrifugal weight can be increased.

[Brief description of drawings]

1 to 5 show an embodiment of the present invention. FIG. 1 is a sectional view taken along line I-I in FIG. 2, and FIG. 2 is II-II in FIG.
3 and 4 are sectional views of essential parts showing different operating states, FIG. 5 is an Np-Θ characteristic diagram, and FIG.
The figure is a different Np-Θ characteristic diagram. 1 ... Timer housing, 3 ... Timer gear, 5 ... Timer hub, 6 ... Flange part, 8 ... Cam shaft, 15 ... First circular cam, 16 ... Second circular cam, 17 ... First 1 pin, 18 ...... 2nd pin, 19 ...... centrifugal weight, 23 ...... guide rod, 25 ...... end spring seat, 27 ...... inner spring seat, 26 ...... shape memory alloy spring, 28 , 29 …… Main spring, 3
2 ... Bias spring.

Claims (1)

(57) [Claims] 1. A timer housing to which a driving force is applied from an internal combustion engine, a pair of centrifugal weights housed in the timer housing and moving toward and away from each other in a radial direction according to rotation, and a radial direction of the pair of centrifugal weights. Guide rod for guiding the movement of the guide rod, the end spring seat attached to the end of the guide rod, and the guide rod slidably attached in the middle of the guide rod so that the centrifugal weight exceeds the predetermined distance. An inner spring seat that is pressed and moved by the centrifugal weight when it moves in the radial direction, and the centrifugal weight that is provided between the end spring seat and the inner spring seat contacts the inner spring seat. A main spring that presses and urges these centrifugal weights toward each other when they move in contact with each other, and is provided between the end spring seat and the centrifugal weight, and along the moving direction of the centrifugal weight. It has a shape memory alloy spring that reduces the initial load when it contracts and falls below a prescribed temperature, a bias spring that reduces the acting force of the shape memory alloy spring above the prescribed temperature, and a flange portion. A timer hub connected to the cam shaft of the injection pump, a pair of first circular cams rotatably inserted in the eccentric position of the flange portion, and rotatably inserted in the eccentric positions of the first circular cams. A fuel injection timing adjustment for an internal combustion engine, comprising: a pair of second circular cams that transmit rotation of the timer housing through a first pin and that are connected to the centrifugal weight through a second pin. apparatus.