JPS6233414B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a rotationally coupled main shaft of an engine and a main shaft of a fuel injection pump, and a centrifugal force acting against a spring in response to changes in the rotational speed of the engine. The present invention relates to a fuel injection timing adjustment device for an internal combustion engine that controls the rotational phase of an engine and a fuel injection pump by utilizing the displacement of a pair of weights that are spread apart from each other.

[Prior art] This type of injection timing adjustment device is disclosed in Japanese Patent Application Laid-open No. 1983-
In the system disclosed in Japanese Patent No. 3617, the injection timing simply advances as the engine speed increases.

The inventors of the present invention have already established that the injection timing is delayed in the low speed range, does not change much in the medium speed range, and advances in the high speed range in response to an increase in the engine rotational speed.
When the distance between the pair of weights changes approximately in proportion to the rotational speed of the engine, the first disc cam that engages eccentrically with the weight, and the first disc cam that engages eccentrically with the first disc cam. a case that supports the second disc cam and is rotationally coupled to the engine via a second disc cam that is jointly supported; a case that supports the first and second disc cams and that injects fuel; The patent application is for a fuel injection timing adjustment device that adjusts the rotational phase between the output shaft and the output shaft that is rotatably coupled to the pump.

However, a fuel injection timing adjustment device having such retard/advance characteristics may operate unstable at an inflection point where the retard angle changes to the advance angle. In other words, in the conventional configuration in which a spring that resists the expansion movement is supported between a pair of centrifugal weights, the weight is affected in the process of moving from the low speed range to the high speed range of the engine, mainly due to disturbances such as torque fluctuations. The expansion movement may not be performed smoothly.

[Problems to be Solved by the Invention] The purpose of the present invention is to solve the above-mentioned problems.
To provide a fuel injection timing adjustment device for an internal combustion engine in which a pair of weights can freely move without restricting each other.

[Means for Solving the Problem] In order to achieve the above object, the configuration of the present invention is such that a rotating body connected to an engine and a rotating body connected to a fuel injection pump are arranged on the same axis, and one A first disc cam is rotatably engaged with and supported at an eccentric position of a cam support plate to which a rotating body is fixed, and weights that are spread apart by centrifugal force are arranged at the eccentric position of the first disc cam. while coupling, rotatably engaging and supporting a second disc cam at an eccentric position of the first disc cam;
The other rotating body is coupled to the eccentric position of the second disc cam, and the coupling point of the other rotating body is located on the front side in the rotational direction of the rotating body with respect to the center of the first disc cam. In a fuel injection timing adjustment device for an internal combustion engine, at both ends of the weights that approach each other,
A shaft consisting of divided bodies fitted and connected so as to be able to slide in the axial direction is supported through the shaft, and between the spring seat and the weight fixed at both ends of the shaft, the expansion movement of the weight is supported. A resisting spring is interposed therein, and sliding bodies made of a low-friction material and slidingly in contact with the inner circumferential surface of the case are supported at both ends of the shaft.

[Function] A shaft that connects both ends of a pair of weights to each other in an expandable manner is composed of a split body that is extendably connected,
A spring is interposed between the spring seat and the weight, which are fixed to both ends of these shafts, and which suppresses the expansion movement of the weight. Since each weight is equipped with a low-friction sliding body that fits together with the other weights, it is possible to move freely due to centrifugal force without being restricted by other weights, and this prevents undesirable effects on the movement of other weights. do not have.

[Embodiments of the Invention] The structure of the present invention will be explained based on the drawings. As shown in FIG. 1, the fuel injection adjustment device includes a cup-shaped case 4 having an end plate 4a rotatably coupled to the main shaft of the engine. This opening end is closed by a cover plate 3 via a seal member 19. At the center of the case 4, a hollow output shaft 16 is rotatably supported at its left end by the cover plate 3, and its rotating portion is sealed by a seal member 2. The space between the right end of the output shaft 16 and the end plate 4a is sealed by a sealing member 7, and a cam support plate 30 that slides on the inner surface of the end plate 4a and the inner peripheral surface of the case 4 is fixedly supported on the right end side. ing. A pair of large circular holes 30a are provided in the cam support plate 30 symmetrically with respect to the center O of the shaft 16 (FIG. 6), and the disk cam 5 is rotatably fitted into the circular holes 30a. A pin 13 is supported eccentrically toward the center of the case 4 than the center of the disc cam 5, and a weight 14 is mounted on the tip side of the pin 13.
is supported. The pin 13 is rotatable relative to either the weight 14 or the disc cam 5. The pair of weights 14 have a semicircular arc shape surrounding the output shaft 16 (FIG. 2), and both ends thereof are connected to each other by a spring so as to approach each other. A circular hole 5a is provided at an eccentric position of the disc cam 5, and a second disc cam 15 is rotatably fitted into the circular hole 5a. The disk cam 15 is attached to the tip of the pin 6 fixed to the end plate 4a.
is rotatably supported at an eccentric position.

A tapered hole is provided at the left end of the output shaft 16,
This is connected to the main shaft 1 of the fuel injection pump via the key 17.
are fitted and fastened with nuts. A screw hole 18 is provided on the right end side of the output shaft 16, into which a closure body (not shown) that is loosely fitted into the opening 8 of the end plate 4a is screwed. Further, the end plate 4a is provided with a hole for filling the inside of the sealed case 4 with lubricant, and a screw plug 10 is provided.
is closed by. 1 on the outer surface of the end plate 4a
A pair of pin holes are provided in which a pair of pins provided on the end flange of the main shaft of the engine are engaged to provide rotational connection with the engine.

As shown in FIG. 2, a large depression 27 is provided at both ends of the weight 14, and a spring seat 21 and a spring seat 21 are secured to both ends of a shaft 24 passing through the center of the depression 27 with retaining rings 28. A coil spring 22 is interposed between the spring seat 25 and the spring seat 25 that abuts inside the recess 27.
A coil spring 23 is interposed between the spring seat 31 and the spring seat 21 that abuts against the stepped portion 12 of the shaft 24, and these springs 22 and 23 cause a spacer 26 to be attached to both ends of the pair of weights. are pressed together through the

According to the present invention, in order to prevent the pair of weights from interfering with each other's movements, the shaft 24 is configured as a divided body connected to each other so as to be slidable in the axial direction at the central portion, as shown in FIG. Both ends are engaged with and supported by the inner peripheral surface of the case 4. For this reason, one divided body of the shaft 24 is provided with a shaft hole 33, while the other divided body is formed with a small diameter shaft portion 24a, which is slidably fitted into the shaft hole 33. Further, shaft holes are provided at both ends of the shaft 24, into which a small diameter shaft portion 32a of a sliding body 32 made of a low friction material is fitted and fixed. The tip of the sliding body 32 is cut into an arc shape and is pressed against the inner peripheral surface of the case 4 by the force of the springs 22 and 23.

As shown in FIGS. 4 and 5, a pair of rollers 35 are supported by a shaft 34 at the flat end of the shaft 24, and the rollers 35 roll on the inner peripheral surface of the case 4. The sliding body 32 may also be configured.

As described above, the cam support plate 30 that is integral with the output shaft 16 has approximately the same diameter as the inner diameter of the case 4, and can rotate differentially with respect to the case 4. The disc cam 5 that supports each weight 14 with a pin 13 and the disc cam 15 that is engaged and supported by the disc cam 5 are arranged symmetrically with respect to the center of the output shaft 16, respectively. And arrow x in case 4
With respect to rotation in the direction, these disc cams 5, 15 are arranged as shown in FIG. That is, the pin 13 supporting the weight is rotated in the rotation direction x with respect to the line connecting the center O of the output shaft 16 and the center C of the disc cam 5.
The pin 6 supported on the rear side of the case 4 and on the side of the case 4
is arranged on the front side in the rotational direction x, eccentric from the center B of the disc cam 15 that supports the pin 6, and on the front side in the rotational direction x, in other words, the center C of the disc cam 5
is arranged radially outward from the center B of the disc cam 15.

Next, the operation of the fuel injection timing adjustment device according to the present invention will be explained. In FIG. 2, when the case 4 is rotated by the engine in the direction of the arrow x, a pair of weights 14 are
The distance between the two is expanded against the force of the springs 22 and 23. Therefore, the mutual spacing between the pins 13 that engage with the center portion of each weight 14 is increased, and the disc cam 5 is rotated counterclockwise. At this time, the disc cam 15 rotates inside the circular hole 5a, and the position of the pin 6 changes. In this way, the change in the mutual spacing of the weights 14 due to centrifugal force is caused by the pins 13 and 6.
This causes a rotational differential between the case 4 and the output shaft 16 to advance the injection timing of the fuel injection pump, or delay.

To explain this relationship in more detail, FIG. 6 shows the relative positions of the disc cams 5, 15 and the pins 13, 6 when the engine is idling. When the rotational speed of the engine increases from this state, the centrifugal force of the weight 14 pushes the pin 13 radially outward from the center O of the output shaft 16. However, since the pin 13 is supported by the disc cam 5, the disc cam 5 is rotated by an angle β in the direction of the arrow y around the center C, and the center D of the pin 13 moves to the position _D1. do.
As the disc cam 5 rotates by the angle β, the disc cam 15
The center B of moves to B'. And disc cam 15
, the pin 6 is fixed to the end plate 4a and remains at a constant radial position from the center O of the output shaft. , the center A of pin 6 moves to _A1 . In this way, the central angle α between the center C of the disc cam 5 and the center A of the pin 6 with respect to the center O increases by the angle θ. This brings about a rotational differential between the output shaft 16 that supports the disc cam 5 via the cam support plate 30 and the end plate 4a that supports the pin 6, and adjusts the injection timing of the injection pump by an angle θ (in the case of a 4-cycle engine). 2θ).

When the rotational speed of the engine further increases as described above, the center D of the pin 13 connected to the weight moves around the center C of the disc cam 5, as shown in FIG.
D ₁ , D ₂ , D ₃ , and similarly the center B of the disc cam 15 moves around the center C of the disc cam 5 by B ₁ , B ₂ , B ₃
and move. The center A of the pin 6 coupled to the case 4 is A ₁ ,
Move to A ₂ and A ₃ . As is clear here, the arm CB of the disc cam 5 (the eccentricity of the disc cam 15 with respect to the disc cam 5) and the arm BA of the disc cam 15 (the eccentricity of the pin 6 with respect to the disc cam 15) are in a straight line. When lined up with
CB and arm BA bend, and angle θ decreases. In other words, the injection timing of the fuel injection pump advances.

As shown in Fig. 8, when the engine is started or idling, the injection timing θ is kept constant by the preload of the spring 22, and in the low speed range _N1 to _N2 , the spring 22 is deflected and the weight expands, causing the injection. The timing is gradually delayed, and in the medium speed range _N2 to _N3 , the spring seat 25 collides with the spring seat 31, and is held in a delayed state by the preload of the spring 23, and in the high speed range _N3 to _N4 , the spring seat 25 is held in a delayed state. The weight expands as it is flexed, gradually advancing the injection timing. Controlling the injection timing in this way not only improves engine startability but also helps to suppress harmful components such as NOx, HC, and CO in exhaust gas in the low-to-medium speed range.

By the way, when the weights 14 are spread apart from each other, one of the weights may suddenly vibrate in the radial direction due to disturbances such as torque fluctuations. In order to prevent such movement, in a conventional device in which a spring is supported between the weights, movement of one weight radially outward causes the other weight to be pulled radially inward via the spring. As a result of the force trying to bring them together, especially in Figure 6, arm CB and arm BA
At rotational speeds N ₂ and N ₃ at which the weight 14 is approximately linear, the smooth movement of the weight 14 may be hindered, resulting in a stalemate, and the normal injection timing adjustment function may not be achieved.

However, according to the present invention, the shaft 24 is divided at the center, and the springs 22 and 23 that bias each weight in the contraction/closing direction substantially connect one end to the case 4.
Because they are supported laterally, the pair of weights can move independently of each other and are not interfered with by the other. Therefore, even if for some reason a force is generated in only one of the weights that causes it to suddenly move in the radial direction, the other weight will not be subjected to unreasonable force, and in the end, the force will be 1. The disc cam operates smoothly in response to the average movement of the pair of weights, and a stable injection timing adjustment effect is obtained, and the amount of retardation can be increased accordingly.

[Effects of the Invention] In short, the present invention arranges a rotating body connected to an engine and a rotating body connected to an injection pump on the same axis, and adjusts the eccentric position of a cam support plate fixed to one of the rotating bodies. A first disc cam is rotatably engaged and supported, and a weight that is spread apart by centrifugal force is coupled to an eccentric position of the first disc cam. A second disc cam is rotatably engaged and supported at an eccentric position, the other rotating body is coupled to the eccentric position of the second disc cam, and the other rotating body is connected to the center of the first disc cam. In a fuel injection timing adjustment device for an internal combustion engine, in which a coupling point of a rotary body is arranged forward of the center of the second disc cam in the rotational direction of the rotary body, the expansion movement of a pair of weights is resisted. The feature is that a spring is independently supported between each weight and the inner circumferential surface of the case that houses the weight, and this configuration allows it to withstand changes in the rotational speed of the engine. On the other hand, an excellent effect can be obtained in that the device operates smoothly and stably at an inflection point where the injection timing changes from a retarded state to an advanced state or vice versa.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a fuel injection timing adjustment device for an internal combustion engine according to the present invention, FIG. 2 is a front sectional view thereof, FIG. 3 is an enlarged view of the main part of FIG. 5 is a sectional view of the same plane, FIGS. 6 and 7 are diagrams explaining the operation of the device of the present invention, and FIG. 8 is a diagram showing the operating characteristics of the device of the present invention. FIG. 3: Lid plate, 4: Case, 5, 15: Disc cam,
6, 13: pin, 5a, 31a: circular hole, 14: weight, 16: output shaft, 21, 25, 31: spring seat,
22, 23: Spring, 24: Shaft, 28: Retaining ring, 3
0: cam support plate, 32: sliding body.

Claims (1)

[Claims] 1 A rotating body connected to the engine and a rotating body connected to the fuel injection pump are arranged on the same axis, and the first disk cam is rotated to an eccentric position of the cam support plate fixed to one of the rotating bodies. the first
Weights that are mutually expanded by centrifugal force are coupled to the eccentric positions of the disc cams, while a second disc cam is rotatably engaged and supported at the eccentric positions of the first disc cam, and An internal combustion engine in which the other rotating body is coupled to an eccentric position of the second disc cam, and a coupling point of the other rotating body is located on the front side in the rotational direction of the rotating body with respect to the center of the first disc cam. In a fuel injection timing adjustment device for an engine, a shaft consisting of a split body that is fitted and connected so as to be slidable in the axial direction is supported through both ends of the weights that are close to each other, and is engaged with both ends of the shaft. A spring is interposed between the stopped spring seat and the weight to resist the expansion movement of the weight, and the spring is made of a low-friction material at both ends of the shaft and is in sliding contact with the inner peripheral surface of the case. A fuel injection timing adjustment device for an internal combustion engine, characterized by supporting a sliding member.