JPS5937232A - Fuel injection timing adjusting device of diesel engine - Google Patents

Abstract

PURPOSE:To simplify the construction of the titled device by a method wherein a drive shaft and a driven shaft are fitted in mesh at the respective ends and the phase between said shafts is changed by axially shifting either one of them. CONSTITUTION:An input disc 2 driven by a crankshaft and an output shaft 7 to drive a fuel injection pump are joined in mesh by means of a pair of helical splines 3. When a shifting shaft 16 is shifted rightward or leftward by means of the actuation of a servomotor 16, the input disc 2 is also shifted axially, resulting in pivoting the output shaft 7 by means of the helical splines 3 and consequently changing the phase between the disc 2 and the shaft 7. Because of being fitted in mesh, the distance between the engine and the injection pump can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection timing adjustment device for a diesel engine, and in particular to an electronic timer.

Generally, in a diesel engine, it is necessary to change the fuel injection timing depending on the operating state. That is, when the fuel injection pump is driven, the pressure generated in the plunger chamber is transmitted in the form of pressure waves at high speed through the high-pressure pipe and reaches the fuel injection nozzle. The fuel injected from the nozzle ignites and burns after a certain ignition delay period. The time it takes for pressure waves to travel through the high-pressure pipe does not change much depending on the engine speed, but the crank angle during the ignition delay period increases as the speed increases. In other words, the ignition time is shorter at higher speeds, but the crank angle is shorter, so the crank angle that rotates from the time when pressure is generated in the granger chamber to the point of ignition becomes larger at higher speeds. Therefore, in order to keep the ignition timing close to a constant regardless of the rotation angle and obtain the optimum combustion condition, the injection timing, that is, the timing at which the fuel injection pump generates pressure, is advanced relative to the engine crank angle at high speeds. I need to do it. In this way, a device that changes the relative rotation angle between the drive shaft of the engine and the fuel injection pump,
As you know, it's called an automatic timer.

This mechanical automatic timer has a simple structure and is a completely independent mechanism that only contains flyweights and springs, so it is screwed onto the end of the fuel camshaft of the fuel injection pump and It can also be installed inside the cylinder body by simply connecting the drive side flange of the timer and the engine side drive shaft with a coupling.

By the way, conventional mechanical automatic timers depend only on the engine rotational speed to determine when to start fuel injection, which is mechanically detected and controlled. In addition to influencing the general performance of the vehicle, maximum explosive force and noise.

Since it has a large effect on startability, exhaust gas characteristics, and especially nitrogen oxide concentration, it is necessary to accurately match the overall optimum value. Therefore, the mechanical automatic timer described above cannot adequately cope with these characteristics, and attempts have been made to adopt an electronic control system. This electronic control system retains the fuel pumping and injection mechanism of the current size pump or distribution pump, but incorporates a so-called electronic control timer that introduces electronic control into the control part of the injection amount and injection timing. It has been developed. The feature of this electronically controlled timer is that it has a large degree of freedom in advance angle characteristics, which makes it easy to correct the timing, and also makes it easy to expand the model range. It is something that contributes.

A specific example of this is an electronically controlled timer using a hydraulically actuated spline system, but in this case, although the complexity of hydraulic circuits and the like can be avoided, production costs tend to increase. In addition, as another example, a special nut is interposed between the drive shaft of the engine and the fuel camshaft of the fuel injection pump, and the end portions of the fuel camshaft and the engine-side drive shaft are steeply inclined with respect to the nut. It has a structure in which a screw is provided and the screw is screwed into the nut.When the nut is rotated by a servo motor and moved in the axial direction, each steeply inclined screw rotates, and the drive shaft and fuel camshaft are connected. rotates relatively. In this case, the complexity of the hydraulic circuit is avoided.

However, in the case of the former example, a complicated hydraulic pressure generating device is required and the cost is high, and the hydraulic pressure generation situation changes depending on the properties and oil temperature of the hydraulic oil, so the property (mainly viscosity) Temperature sensors and their corrective controls may be required, further increasing complexity and cost.

In the latter case, the distance between the engine side and the fuel injection pump is longer, the engine side surface is still complicated, and the number of parts is large because there is a connecting member made of a special nut, resulting in a complicated structure and high cost. In any case, the simple structure and compact features of conventional mechanical automatic timers have an advantage that cannot be matched.

Therefore, the present invention was created to solve the problems of conventional electronically controlled timers.
It is an object of the present invention to provide a fuel injection timing adjustment device that is small and compact and does not take up much space, while enabling comprehensively appropriate control.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the present invention will be described below with reference to embodiments shown in the accompanying drawings. Reference numeral 1 denotes a fuel camshaft gear made of a spur gear, which is loosely fitted onto a fuel camshaft 4 horizontally suspended in a cylinder body 19. 2 is an input desk, and a bolt 20 is attached to the side of the fuel camshaft gear 1. It is fixed by a knock bottle 21. A cylindrical output shaft 7 integrated with a key 5 is fitted to the outer end of the fuel camshaft 4, and is prevented from being pulled out with an end nut 6.

On the inside of the output shaft 7, the fuel camshaft gear 1 is supported on its outer periphery via a bearing 22, and on the outside, a helical spline 3 is carved on the outer periphery, and it meshes with the input desk 2 via the spline 3. There is.

The axis of the fuel camshaft 4 is the center of the moving shaft 16. The input desk 2 is rotatably connected to the input desk 2 via angular ball bearings 10+10. The input desk 2 has a stepped portion 23, 2'3 and a retaining ring 11 for the hole.
and a retaining ring 12 for the shaft, holding the ball bearing 10.10 and the moving shaft 16.

The above parts are built into the cylinder body 19,
A side cover 9 is fixed to the cylinder body 19 with bolts 24, and a servo motor 1 is integrated with a gear head 14 on the outside of the side cover 9.
5 is installed protrudingly. A threaded shaft 13 projects from the gear head 14 onto the axis of the fuel camshaft 4, and the threaded shaft 13 and a moving shaft 16 are screwed together. A rotation stopper pin 7 projects inside the side cover 9 and is slidably inserted outside the axis of the moving shaft 16.

Since this embodiment has the above configuration, the fuel camshaft gear 1 is rotated by the meshing of the drive gear 18 driven by the engine crankshaft (not shown), and the input desk 2 integrated therewith is also rotated. Rotate. As the input desk 2 rotates, the output shaft 7 connected by a helical spline 3 rotates, and the fuel camshaft 4 connected to the output shaft 7 by a key 5 rotates.

The fuel camshaft 4 drives a fuel injection pump (not shown).

Next, the servo motor 15 is controlled by the output of a microcomputer (not shown) inputted by a sensor of at least one of control factors such as engine rotational speed, load, combustion chamber temperature, or rotational acceleration. When the threaded shaft 13 rotates due to the operation of the servo motor 15, the moving shaft 16
Since the rotation of the shaft 16 is stopped by the side cover 9 by a rotation stopper pin 17, the shaft 16 can move to either the left or right. Due to this axial movement, the input desk 2 integrated with the fuel camshaft gear 1 also moves in the axial direction, and as a result, the output shaft 7 is rotated by the helical spline 3, and the input desk 2 is rotated by the helical spline 3.
The phase between the output shaft 7 and the output shaft 7 is slightly changed. Therefore, the phase change similar to the mechanical automatic timer is performed to change the fuel injection start timing.

In the above embodiment, a spur gear is used as the fuel camshaft gear l, and a helical spline 3 is used for meshing the input desk 2 and the output shaft 7. However, if a helical gear is used as the fuel cam gear 1, the input For the engagement between the desk 2 and the output shaft 7, a rectangular or helical spline may be used.

In summary, the present invention provides a fuel injection timing adjustment device that connects an engine-side drive shaft and a fuel injection pump-side driven shaft and changes the phase of a fuel camshaft of the pump at the connection portion. These members are fitted into each other in a meshing state at each end, and these members are housed in a cylinder body, and either the driving shaft or the driven shaft is moved in the axial direction by a servo motor controlled by a microcomputer. Since this is a fuel injection timing adjustment device for a diesel engine that changes the relative rotation angle between the drive shaft and the driven shaft, it has the following effects.

■The rotation of a servo motor controlled by a microcomputer provides comprehensive optimal control of the fuel injection start timing in response to the engine's rotational speed, load, etc., and achieves low fuel consumption and low fuel consumption. It can contribute to pollution, etc.

■Since the drive shaft and driven shaft are fitted in a mutually meshing state, it does not take up much space, unlike when they are connected in the axial direction.

■Since the meshing part between the drive shaft and the driven shaft can be housed within the cylinder body, the engine's lubricating oil can be used, and no special oil lubrication device is required.

■If the servo motor is installed outside the cylinder body,
Not affected by engine temperature.

[Brief explanation of drawings]

The accompanying drawings show cross-sectional views of embodiments of the invention. 1...Fuel cam gear, 2...Input desk, 3...
Helical spline, 4... Fuel cam shaft, 7... Output shaft, 13... Threaded shaft, 15... Servo motor, 19... Cylinder body. Agent Patent Attorney Yoshihiko Okabe

Claims (1)

[Claims] In a fuel injection timing adjustment device that connects an engine-side drive shaft and a fuel injection pump-side driven shaft and changes the phase of the fuel camshaft of the pump at the connection portion, each end of the drive shaft and the driven shaft are mutually connected. The two shafts are fitted in a meshing state, and these members are housed in the cylinder body.A servo motor controlled by a microcontroller moves one of the shafts in the axial direction, thereby adjusting the relative relationship between the drive shaft and the driven shaft. Diesel engine fuel injection timing adjustment device that changes the rotation angle