JPS649454B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device that automatically adjusts fuel injection timing according to the rotational speed of an engine.

Generally, in a diesel engine or the like, the fuel injection timing is controlled to be advanced as the rotational speed is increased so that fuel injection is always performed at the highest pressure point.

As a typical example of this type of fuel injection timing adjustment device (referred to as an automatic timer), the rotation of a drive flange connected to the engine is transmitted to a pair of timing weights, and when these timing weights are displaced by centrifugal force, this displacement is transmitted to the driven flange of the timer hub via a large eccentric cam and a small eccentric cam, and the timer hub is angularly displaced relative to the drive flange, thereby advancing the drive shaft of the fuel injection pump. It is known that the fuel injection timing is rotated to relatively advance the fuel injection timing.

In a device using a timing weight that is displaced in the radial direction by centrifugal force, a pair of support rods are passed between the pair of timing weights, and the movement of the timing weight is guided by these support rods. A spring is attached to the support rod to generate an urging force for returning the timing weight. However, in such a configuration, the centrifugal force of the timing weight is small in the low-speed rotation region, and
The tension of the spring that presses this timing weight is also small, and in addition, the engine torque fluctuation is unstable, so the influence of processing errors and assembly errors is large, and the timing weight tends to wobble, and the timing weight of both timing weights is unstable. Their postures also tend to tilt from their normal positions. If one timing weight is tilted, the tension of the spring changes, making it difficult for the left and right timing weights to operate equally.

For this reason, for example, in the Np-θ characteristic diagram of the timer shown in Figure 1 (Np is the rotation speed, θ is the timer advance angle), for the required characteristic such as A in the low speed rotation range, As a result of this, there are problems such as the engine not being able to fully demonstrate its performance and poor restartability after stopping the engine.

The present invention has been made based on the above circumstances, and is designed to maintain the timing weights in a uniform posture even in the low rotation range, so that the timing weights are moved evenly, and to prevent variations in timer characteristics. The purpose of the present invention is to provide a fuel injection timing adjustment device for an internal combustion engine.

That is, in the present invention, a plate rotatable with respect to the timer hub is attached to the timer hub or the casing, and guide grooves are provided in the plate at symmetrical positions with respect to the center of rotation, and these guide grooves include:
A pin connected to a timing weight is slidably fitted into the timing weight, and is characterized in that the posture of the pair of left and right timing weights is maintained equally by the plate.

An embodiment of the present invention will be described below with reference to FIGS. 2 and 3.

In the figure, reference numeral 1 denotes a drive flange, which is connected to the crankshaft of an engine (not shown) and rotated in synchronization with the engine. 2 is a timer hub, and a drive shaft 3 forms a camshaft of a fuel injection pump (not shown).
are connected by a nut 4 so as to rotate together. The timer hub 2 is integrally provided with a driven flange 5 facing the drive flange 1, and a holding flange 7 is attached to the driven flange 5 via bolts 6. The holding flange 7 restrains the driving flange 1 so that it cannot move in the axial direction by the stepped portion 8, but is fitted to the driving flange 1 so as to be rotatable relative to the driving flange 1. Therefore, the timer hub 2 is rotatable relative to the drive flange 1.

The driven flange 5 has circular holes 9 located symmetrically to each other.
a, 9b are opened, and these circular holes 9a, 9
Disc-shaped large eccentric cams 10a and 10b are rotatably fitted into b. Large eccentric cam 10a, 10
Small circular holes 11a and 11b are provided at eccentric positions in b, respectively.
are drilled, and these small circular holes 11a, 11b
Small eccentric cams 12a and 12b are rotatably fitted inside. Second eccentric pins 13a, 13b are press-fitted into the small eccentric cams 12a, 12b at eccentric positions, and these second eccentric pins 13a, 13b are rotatably fitted into the drive flange 1.

Furthermore, first eccentric pins 14a, 14b are protruded from the large eccentric cams 10a, 10b at eccentric positions, and these first eccentric pins 14a, 14b are press-fitted and connected to timing weights 15a, 15b.

The timing weights 15a and 15b are divided into two in the radial direction, and are arranged on the outer periphery of the timer hub 2 so as to surround the timer hub 2. These timing weights 15a, 15b
are arranged to spread out from each other when they are displaced outwardly by centrifugal force. Rods 16, 16 are passed through between the timing weights 15a, 15b, and these rods 16, 16 guide the movement of the timing weights 15a, 15b in the radial direction, and also serve to support the return springs 17... ing. The return springs 17... are bridged between the spring receivers 18... provided at the ends of each rod 16, 16 and the timing weights 15a, 15b, and press the timing weights 15a, 15b in a direction toward each other. It is strong.

A plate 20 is provided at the end of the timer hub 2 opposite to the driven flange 5. Although the plate 20 is prevented from being pulled out in the axial direction of the timer hub 2 by a circlip 21, it is rotatably fitted to the timer hub 2.
The plate 20 maintains a space between the driven flange 5 and the timing weights 15a and 15b so that the timing weights 15a and 15b can freely move in the radial direction. 22a and 22b are formed. These guide grooves 22a and 22b are provided so as to be inclined to each other with respect to the radial direction. Guide pins 23a and 23b are slidably inserted into these guide grooves 22a and 22b, respectively, and these guide pins 23a and 23b are press-fitted and connected to timing weights 15a and 15b, respectively, at symmetrical positions. ing.

The operation of the embodiment based on such a configuration will be explained.

When the rotation of the engine is transmitted to the drive flange 1, the small eccentric cams 12a, 12b and the large eccentric cam 10a,
10b is rotated around the drive shaft 3, the timer hub 2 is rotated via the driven flange 5. Therefore, the rotation of the engine is transmitted to the drive shaft 3 to drive the fuel injection pump.

The rotation of the drive flange 1 and timer hub 2 also rotates the timing weights 15a and 15b. When the rotational speed of the drive flange 1 is increased,
The centrifugal force of the timing weights 15a, 15b increases, and the timing weights 15a, 15b are expanded and displaced against the urging force of the return springs 17. The timing weights 15a, 15b are moved in the outer radial direction by the first eccentric pins 14a, 14b.
3 to push the large eccentric cams 10a, 10b in the direction of arrow C in FIG. Therefore, the large eccentric cams 10a, 1
0b is rotated in the direction of arrow D within the circular holes 9a and 9b. Such rotation of the large eccentric cams 10a, 10b attempts to rotate the small eccentric cams 12a, 12b in the direction of arrow D, but the small eccentric cams 10a, 10
b is rotatably attached to the drive flange 1 via the second eccentric pins 13a and 13b, so it rotates in the direction of arrow E. As a result, the second eccentric pins 13a, 13b are displaced in the circumferential direction around the timer hub 2. Therefore, since the circumferential position of the drive flange 1 relative to the timer hub 2 changes, conversely, the position of the timer hub 2 relative to the drive flange 1 changes.
will be relatively advanced.

As a result, the injection timing of the fuel injection pump can be advanced with respect to the engine speed Np.

Therefore, the timing weight 1 as described above
When moving 5a and 15b to expand, each weight 15
Since the weights 15a and 15b are connected to the plate 20 via the guide pins 23a and 23b, the centrifugal strokes of both weights 15a and 15b are regulated to be equal. That is, for example, when one timing weight 15a attempts to move in the outer radial direction to a greater extent than the other weight 15b, the guide pin 23a connected to this timing weight 15a is also integrally displaced in the outer radial direction to a greater extent. be done. This guide pin 23a attempts to move in the outer diameter direction within one guide groove 22a formed in the plate 20. Since the guide groove 22a is inclined with respect to the radial direction, the cam action of the guide groove 22a moves the plate 20 in the direction indicated by the arrow F.
Rotate in the direction. Since the rotation of the plate 20 in the direction of arrow F also rotates the other guide groove 22b, the guide pin 23b protruding from the other timing weight 15b is moved in the outer radial direction.
In other words, the other timing weight 15b has to move by the same amount as the one timing weight 15a, and therefore both weights 15a, 15
b have equal centrifugal displacement.

Note that even when the engine is decelerated and operated at a retarded angle, the centrifugal strokes of the timing weights 15a and 15b are matched with each other.

According to this configuration, timing weight 1
Since strokes 5a and 15b are maintained at equal strokes, variations in characteristics are eliminated, and required characteristics A shown in FIG. 1 can be achieved with high accuracy. Especially in the low speed rotation region, the centrifugal force generated in the timing weights 15a, 15b is small, and the return springs 17...
Even when the pressing force of the weights 15a and 15 is small and the engine torque fluctuation is unstable,
Since the posture and stroke of b are kept uniform, variations in characteristics are prevented.

Note that the present invention is not limited to the above-mentioned embodiment, but may be constructed as in the second embodiment shown in FIGS. 4 and 5, for example. In this second embodiment, another plate 40 is arranged between the driven flange 5 and the timing weights 15a, 15b so as to be rotatable with respect to the timer hub 2, and the plate 40 has guide grooves 41a, 41b. has been established.
These guide grooves 41a, 41b are provided with timing weights 15a, 15b and a large eccentric cam 10.
the first eccentric pin 14 that connects the
a, 14b are slidably penetrated therethrough, and these first eccentric pins 14a, 14b also serve as guide pins 23a, 23b in the first embodiment. Note that slidable collars 42a, 42b made of Teflon or the like are fitted to the first eccentric pins 14a, 14b in order to smooth the sliding movement with the guide grooves 41a, 41b.

Even in such a second embodiment, the same effects as in the first embodiment are achieved.

Furthermore, the present invention may be a third embodiment shown in FIG. This is a type in which a casing 60 and a closing plate 61 are attached to the drive flange 1, and lubricating oil is sealed inside using oil seals 62, 62. A plate 40 similar to that of the second embodiment is provided between them, and guide grooves 41a and 41b (only one is shown) are formed in this plate 40.

Note that each plate 20, 40 may also have the function of receiving a thrust load.

Further, each plate 20, 40 is not limited to being attached to the timer hub, but may be attached to the casing 60, and in this case as well, the plates only need to be rotatable relative to the timer hub.

As described above, the present invention provides guide grooves at symmetrical positions with respect to the center of rotation on a plate that is rotatable relative to the timer hub, and allows pins connected to timing weights to slide into these guide grooves. Since the two timing weights are fitted into each other, the centrifugal stroke and posture of both timing weights are regulated by the plate via the pin and the guide groove, thereby maintaining an even stroke. Therefore, variations in the stroke between both weights are prevented, and there is an advantage that the required properties are exhibited with high accuracy without causing variations in the timer characteristics.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the advance angle characteristics with respect to the rotation speed of the timer, Figs. 2 and 3 show the first embodiment of the present invention, Fig. 2 is a longitudinal sectional view, and Fig. 3 is a partial sectional view. The side view, FIGS. 4 and 5 show the second aspect of the present invention.
FIG. 4 is a longitudinal sectional view, FIG. 5 is a partially sectional side view, and FIG. 6 is a longitudinal sectional view showing a third embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Drive flange, 2... Timer hub, 5... Driven flange, 10a, 10b... Large eccentric cam, 12
a, 12b...Small eccentric cam, 13a, 13b...Second
Eccentric pins, 14a, 14b...first eccentric pins,
15a, 15b...timing weight, 20, 4
0...Plate, 22a, 22b, 41a, 41b
...Guide groove, 23a, 23b...Guide pin.

Claims (1)

[Claims] 1 The rotation of the drive flange driven by the engine is transmitted to a pair of timing weights, and these timing weights are expanded and displaced in the radial direction by centrifugal force against the biasing force of the spring, and the expansion displacement of these timing weights is The first
The rotation of the small eccentric cam is transmitted to the large eccentric cam via the eccentric pin of the second
A fuel injection timing adjustment device that transmits a signal to a timer hub connected to a drive shaft of a fuel injection pump by an eccentric pin, and relatively angularly displaces the drive flange and the timer hub according to the rotational speed. A rotatable plate is attached, and guide grooves are formed in the plate at symmetrical positions with respect to the center of rotation, and pins connected to the timing weights are slidably inserted into these guide grooves. Fuel injection timing adjustment device for internal combustion engines.