JPH0328569B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a fuel injection timing adjustment device for a fuel injection pump.

(Technical background of the invention and its problems) In diesel engines such as automobile diesel engines, which have a wide range of operating speeds, the fuel injection timing is changed according to the engine operating condition in order to always obtain optimal operating performance. There is a need. Therefore, in the in-line fuel injection pump, a piston is driven by fluid pressure according to the operating state of the engine, and the piston causes an integral slider arranged at diametrically opposed positions to expand radially outward against the spring force. An injection timing adjustment device that converts the expansion movement in the radial direction into rotational movement in the circumferential direction by a double eccentric cam mechanism that engages with the expansion slider is connected to the output shaft of the engine and the fuel injection pump. The camshaft is connected between the engine and the camshaft, and the relative rotational phase angle between the output shaft and the camshaft is changed according to the operating state of the engine to perform an advance action and adjust the injection timing. . Such an injection timing adjustment device is disclosed in, for example, Japanese Patent Laid-Open No. 188734/1983.

However, the conventional injection timing adjustment device has a member such as a slider that receives centrifugal force,
The action of this centrifugal force limits the control range of injection timing during high-speed rotation, and if the spring force is strengthened to cancel the centrifugal force, there is a problem in that injection timing control at low speed and low oil pressure of the mechanism will be hindered. , there are problems such as limited freedom in design.

(Object of the Invention) The present invention has been made in view of the above-mentioned points, and enables smooth advance angle control, that is, injection timing control, by eliminating members that are subject to the action of centrifugal force, regardless of the high or low engine rotation speed. The purpose is to improve controllability.

(Summary of the invention) In order to achieve the above object, the present invention includes:
Fuel injection timing adjustment equipped with an eccentric cam mechanism that is disposed between an input member connected to the output shaft of the engine and an output member connected to the camshaft of the fuel injection pump, and adjusts the rotational phase between these two members. In the device,
a piston that moves in the axial direction in response to fluid pressure depending on the operating state of the engine; a spring that presses the piston against the fluid pressure; and a spring that engages the eccentric cam mechanism and the piston. a ring that rotates in accordance with the movement of the fuel in the axial direction, and controls the rotational phase angle of the input member and the output member by the cooperative action of the fluid pressure and the spring pressure of the spring to control the rotational phase angle of the input member and the output member, The present invention provides a fuel injection timing adjustment device that advances an injection pump and controls fuel injection time.

(Embodiment of the Invention) An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows a vertical cross-sectional view of an injection timing adjustment device to which the present invention is applied, and FIG. 2 shows an assembled perspective view of a partially cutaway main part of FIG. is screwed and fixed to the pump housing 5 of the fuel injection pump 4 and supported on the camshaft 7 via the bearing 6, and one end of the hub 8a of the rotating member 8 constituting the output member is attached to one end of the camshaft 7. When fitted, the shaft hole 2 of the fixed flange 2
A is rotatably fitted in a liquid-tight manner via a seal member 9, and is screwed and fixed to the camshaft 7 by a nut 10. A notch 8b is provided at a predetermined position on the circumferential surface of the hub 8a of the rotating member 8, and a disc portion 8c integrally provided at the other end of the hub 8a has a double eccentric cam mechanism at diametrically opposed positions. 11, 11' (Fig. 2)
is provided.

As shown in FIG. 2, the double eccentric cam mechanism 11 includes a large cam 12 rotatably fitted into a hole drilled in the disk portion 8c, and a large cam 12 rotatably fitted in a hole drilled in the large cam 12. A small cam 13 is rotatably fitted to the hub 8a, one end of which is fixed to an eccentric position of the large cam 12, and a hub 8a.
A rotating flange 18 (described later) is located at an eccentric position of the small cam 13.
A hole 13a is formed to rotatably support one end of a pin 15 extending parallel to the axial direction of the hub 8a press-fitted into the hub 8a. The double eccentric cam mechanism 11' is also constructed in exactly the same manner as the double eccentric cam mechanism 11.

The rotating cover 16 is externally fitted onto the hub 8a of the rotating rotating member 8, and is rotatably fitted into the shaft hole of the fixed flange 2 through a sealing member in a fluid-tight manner, and is also connected to the fixed flange 2 via a member 17. It is fitted inside the open end of. The rotating flange 18 has a substantially bowl shape and is rotatably fitted onto the disk portion 8c of the rotating member 8, and its open end is screwed and fixed to the rotating cover 16 via bolts 19, and the rotating flange 18 and the rotating cover 16 A casing serving as an input member is formed by the above.

A piston 20, a ring 21, a return spring 22, etc. are housed in the casing, and the piston 20 is externally fitted onto the hub 8a of the rotating member 8 so as to be slidable liquid-tightly in the axial direction, as shown in FIG. There are pins 2 protruding radially outward at both diametrical ends of the circumferential surface.
3 and 23' are fixed, and the disk portion 8c of the rotating member 8
The opposite end has a guide hole 20 at a diametrically opposite position.
a, 20a' are drilled. Guide pins 24 and 24', each of which has one end fixed to the disk portion 8c, are slidably fitted into each of the guide holes 20a and 20a'.

The ring 21 is formed as shown in FIG. 2, with each end opening at a predetermined position on the circumferential surface 21a at both ends on the diameter of the end surface 21b, and openings in the same direction toward the end surface 21c at a predetermined angle with the axial direction. Two grooves 21d and 21d' extending from the end surface 21c are provided at predetermined positions on the end surface 21c.
Two grooves 21e and 21e' extending in the direction 1b are provided. This ring 21 is rotatably fitted onto the piston 20, and both end surfaces 21b and 21c are connected to the rotating cover 16 and the rotating member 8, respectively, as shown in FIG.
The disc portion 8c is disposed so as to be freely displaceable between the end faces of the disc portion 8c. The pins 23, 23' of the piston 20 are slidably fitted into the grooves 21d, 21d', and the grooves 21e, 21d' are slidably fitted into the grooves 21d, 21d'.
21e', each pin 14 of the double eccentric cam mechanism 11, 11' to be provided on the disk portion 8c of the rotating member 8;
14' is fitted. Double eccentric cam mechanism 11,1
Each hole 13a, 13 of the small cam 13, 13' of 1'
Pins 15, 15' press-fitted into the rotating flange 18 are fitted into a' (FIG. 2). The return spring 22 is loosely fitted to the outside of the boss 8a of the rotating member 8, and has one end in pressure contact with the piston 20 and the other end in pressure contact with the disc-shaped 8c via the spring seat 25, so that the piston 20 is pressed against the rotating cover 16.
press against.

A hydraulic chamber 26 is defined between the end surface 20b of the piston 20 and the opposite end surface of the rotating cover 16, and the hydraulic chamber 26 is connected to a passage 2b that is radially bored in the fixed flange 2 through a notch 8b of the boss 8a. The other end of the passage 2b is connected to a pressure control valve 35 via a connecting joint 27, and the pressure control valve 3
5 is connected to a hydraulic pump 36.

A chamber 28 defined between an end surface 20c of the piston 20 and an opposing end surface of the rotary cover 16 has a hole 16a formed in the rotary cover 16, and a hole 16a formed in the rotary cover 16.
6 and the fixed flange 2 through a chamber 29 that communicates with one end of a passage 2c bored in the fixed flange 2 in the radial direction, and the other end of the passage 2c is connected to a connecting joint 30. It is connected to the oil tank 37 via the oil tank 37.

A plurality of holes 18c (only one is shown) are bored at predetermined positions on the end surface 18a of the rotary flange 18, and the rotary flange 18 is connected to the output shaft of the engine (both are (not shown)
connected to. In this way, the output shaft of the engine and the camshaft 7 of the fuel injection pump 4 are connected via the injection timing adjustment device 1.

The control circuit 40 receives input from various sensors that detect the operating state of the engine, such as a rotational speed N, an absolute intake pipe pressure P _B , a water temperature T W, etc. input from a rotation sensor 41, an intake pipe absolute pressure sensor 42, a cooling water temperature sensor ₄₃ , etc. determine the operating state of the engine based on a signal corresponding to the
A control signal is output in accordance with the operating state to control the pressure control valve 35 and adjust the oil pressure supplied to the oil pressure chamber 26 of the fuel injection timing adjustment device 1.

In this configuration, when the hydraulic pressure supplied to the hydraulic chamber 26 is low, the piston 20 is pushed leftward by the spring 22 as shown in FIG.
The pins 23, 23' fit into the grooves 21d, 21 of the ring 21.
d', and in this state, the disc part 8c of the rotating member 8 and the rotating flange 18
The rotational phase angle between is 0.

The hydraulic pressure supplied to the hydraulic chamber 26 increases, and the piston 20 moves against the spring force of the spring 22 to the right as shown by arrow A in FIGS.
24', the pins 23, 23' of the piston 20 rotate the ring 21 in the direction indicated by arrow C in FIG. As the ring 21 rotates in the direction of arrow C, the rotating member 8
double eccentric cam mechanism 11, 11' large cam 12,
12' rotates in the direction of arrow C, and the small cams 13,1
3' rotates in the direction shown by arrow CC'. In response to the rotation of the small cams 13, 13', the rotating flange 18, which is engaged via pins 15, 15', is rotated in the same direction as these small cams 13, 13'.

Therefore, when the output shaft of the engine and the camshaft 7 rotate in the direction of arrow C in FIG. It will be rotated,
A phase angle in the rotational direction is generated between the engine output shaft and the camshaft 7, and the rotation angle of the camshaft 7 advances the rotation angle of the engine output shaft by the phase angle. As a result, the injection timing of the fuel injection pump 4 is advanced in accordance with the phase angle.

On the other hand, when the oil pressure in the hydraulic chamber 26 is lowered, the piston 20 moves to the left by the spring force of the spring 22, and as a result, the rotational phase angle becomes smaller and the injection timing is retarded. In this way, the fuel injection timing can be adjusted depending on the operating state of the engine.

(Effects of the Invention) As described above, according to the present invention, the input member connected to the output of the engine and the output member connected to the camshaft of the fuel injection pump are arranged between the two members. A fuel injection timing adjustment device equipped with an eccentric cam mechanism that adjusts a rotational phase includes a piston that moves in an axial direction in response to fluid pressure depending on the operating state of the mechanism, and a piston that is pressed against the fluid pressure. a spring that engages with the eccentric cam mechanism and the piston and rotates in accordance with the movement of the piston in the axial direction; Since the rotational phase angle between the input member and the output member is controlled, there are no members that operate under centrifugal force, and it is possible to always smoothly control the rotational phase angle regardless of the high or low engine rotational speed. At the same time, controllability is improved, and it becomes possible to smoothly adjust the fuel injection timing in the entire operating range of the engine, making it possible to improve the operating performance of the engine. Furthermore, it is possible to reduce the number of parts, thereby achieving excellent effects such as making it possible to reduce costs.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view showing an embodiment of a fuel injection timing adjustment device according to the present invention, and FIG. 2 is an assembled perspective view of a partially cut away essential part of FIG. 2... Fixed flange, 7... Camshaft, 8... Rotating member, 11, 11'... Double eccentric cam mechanism, 1
6... Rotating cover, 18... Rotating flange, 20
... Piston, 21 ... Ring, 22 ... Spring, 35 ... Pressure control valve, 40 ... Control circuit,
41-43...Sensor.

Claims (1)

[Claims] 1. A fuel timing system equipped with an eccentric cam mechanism that is disposed between an input member connected to the output shaft of the engine and an output member connected to the camshaft of the fuel injection pump, and that adjusts the rotational phase between these two members. In the adjustment device, a piston that moves in an axial direction in response to fluid pressure depending on the operating state of the engine, a spring that presses the piston against the fluid pressure, and an eccentric cam mechanism that is connected to the piston. and a ring that rotates in response to the movement of the piston in the axial direction, and controls the rotational phase angle of the input member and the output member by the cooperative action of the fluid pressure and the spring pressure of the spring. A fuel injection timing adjustment device characterized in that the fuel injection timing is controlled by advancing the fuel injection pump.