JPS6313019B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a timer device for a fuel injection pump.

Generally, in fuel injection pumps for internal combustion engines,
Various timer devices are used to obtain the required injection advance angle, but in the conventional electronic fluid timer device that uses engine lubricating oil as the working fluid, the lubricating oil is used at the time of startup. Since pressure cannot be obtained, it has the disadvantage that a starting advance angle cannot be given. Therefore, as a timer that improves this drawback, a hydraulic timer with a structure combined with an eccentric cam is used (Japanese Patent Application Laid-Open No.
55-5493, JP-A-55-5494).

As shown in FIG. 1, this hydraulic timer has a first eccentric that is fitted with a driven side disc 2 that is integrally formed with the driven side shaft 1 or fixed so as to rotate together with the driven side shaft 1. cam 3 and this first eccentric cam 3
The second eccentric cam 4 is fitted with the second eccentric cam 4.
FIG. 2 shows the assembled state of the driven disk 2 and these eccentric cams. As can be seen from FIGS. 1 and 2, a pin 6 fixed to a piston 7 is engaged with the first eccentric cam 3, while a pin 6 fixed to the piston 7 is engaged with the first eccentric cam 3.
A pin 8 fixed to the drive-side disk 5 is engaged with the eccentric cam 4. The piston 7 is housed in a cylinder 9 rotatably attached to the driven shaft 1, and is biased by a spring 10. The driven shaft 1 is an injection pump (not shown)
Pressurized lubricating oil is supplied from a hydraulic device 14 to the hollow portion 12 of the driven shaft 1 via a pipe 13. A hydraulic system 14 pumps lubricating oil 16 in a tank 15 to a pump 1.
7 and sends it to the pipe 13 through the throttle 19, and the pipe 13 is connected to the tank 15 through an oil passage 20 having a solenoid valve 18.
Therefore, by adjusting the opening degree of the solenoid valve 18, the pressure within the hollow portion 12 changes. cylinder 9
Since a passage 21 that communicates the chamber of the solenoid valve 1 with the hollow part 12 is formed on the driven side shaft, the solenoid valve 1
The position of the piston can be controlled by controlling the opening degree of the piston 8, and when no oil pressure is applied, the position of the piston changes depending on the rotational speed due to the weight of the piston 7. Since the driven side disc 2 and the driving side disc 5 are connected via two eccentric cams and two pins as described above, the movement of the piston 7 causes the eccentric cams 3 and 4 to rotate. The pin 8 performs a circular motion relative to the shaft 1 about the axis of the driven shaft 1, thereby controlling the rotational angular position of the driving disc, that is, controlling the advance angle.

By the way, in this type of timer device, by appropriately adjusting the eccentric position of the eccentric cam,
The advance angle value θ set by this timer with respect to the change in the piston stroke 1 of the piston 7 is set as shown in FIG. 3, thereby giving a starting advance angle θ ₀ . Note that the state of l=0 corresponds to the state of the piston position shown in FIG.
However, when the timer is used with the start angle characteristic shown in Figure 3, there are two piston stroke positions that give the same advance value, and the target advance value and actual advance value are simply different. In the conventional solenoid valve control by comparison, when the advance angle value is near zero, if the value of l becomes smaller than the piston stroke value _l1 that gives θ=0 due to torque fluctuation, etc.
It had a problem that it converged to =0.

Therefore, an object of the present invention is to eliminate the drawbacks of the prior art described above, and to provide a hydraulic system that connects the driven side and the driving side by an eccentric cam assembly and operates with an advance angle characteristic with starting advance angle. It is an object of the present invention to provide a timer device for a fuel injection pump that can stably control a formula timer regardless of the piston stroke value and obtain desired starting advance angle characteristics.

Hereinafter, the present invention will be explained in detail with reference to illustrated embodiments.

FIG. 4 shows a timer device according to the invention. The mechanical configuration of the timer device 30 is almost the same as the mechanical configuration of the timer shown in FIG. has been adjusted to. Therefore, in FIG. 4, the same reference numerals are given to the parts corresponding to those in FIG. 1, and the explanation thereof will be omitted. As can be seen from FIG. 3, the advance angle characteristic of the timer device 30 has a characteristic curve whose slope is reversed depending on whether the piston stroke l is larger or smaller than _l1 . There are two stroke values. Therefore, in order to detect whether the advance angle value is determined by a characteristic curve with a positive or negative slope, a switch 32 is provided which is operated by an operating pin 31 fixed to the piston 7. The switch 32 indicates that the stroke l of the piston 7 is
This is a device for determining whether l is larger or smaller than l ₁ , and as will be described in detail later, if l < l ₁ , the level of the output signal S ₉ output to the output line 32a is set to "1", In the case of l>l ₁ , the position of the operating pin 31 is adjusted so that the level of the output signal _S9 is set to "0". Therefore, depending on the level of the output signal _S9 , it can be determined whether the characteristic curve with a positive or negative slope is used. The control device 40 to which the output signal _S9 is input controls the opening and closing of the electromagnetic valve 18 so as to obtain the advance angle characteristics with the starting advance angle shown in FIG.

FIG. 5 shows a block diagram of the control system shown in FIG. 4. The control device 40 includes a rotation detector 38 that generates a rotation signal S ₁ related to the rotation speed N of the engine (not shown), and an actual advance angle signal S ₂ that indicates the actual injection advance angle θ _a of the fuel injection pump. The actual advance angle detector 33 outputs the actual advance angle. The rotation signal S ₁ is input to the target advance angle calculator 34, and a target advance angle signal S ₃ indicating the target advance angle θ _b according to the target advance angle characteristics shown in FIG.
is output. The actual advance angle signal S ₂ and the target advance angle signal S ₃ are input to a comparison circuit 35, and a detection signal S ₄ is output. The detection signal S ₄ is "1" when θ _a < θ _b
On the other hand, when θ _a ≧θ _b , the signal is a binary signal that becomes “0” level. The detection signal _S4 is input to the drive circuit 37 via a level conversion circuit 36, which will be described in detail later. The drive circuit 37 includes a solenoid valve 18
A pulse signal for exciting the excitation coil 18a of
This is a circuit that generates _S5 , and the level conversion circuit 36
The duty ratio of the pulse signal _S5 is controlled to change depending on the level of the output signal _{S6 from the pulse signal S6} . In the illustrated example, if the level of the output signal S ₆ is "1",
By decreasing the average opening degree of the solenoid valve 18 (see FIG. 1), l increases. On the other hand, when the level of the output signal _S6 is "0", l becomes small.

The switch 32 has fixed contacts a and b connected to the ground and a positive voltage source V _cc , respectively, and when l<l ₁ , the movable contact c is switched as shown by the solid line in the figure, and the output signal S ₉ is The level is "1".
However, when l> _l1 , the switch 32 is switched as shown by the dotted line, and the level of the output signal _S9 becomes "0". This output signal _S9 is input as a control signal to the level conversion circuit 36, and when the level of the signal _S9 is "0", the level conversion circuit 36 inverts the level of the detection signal _S4. without detection signal
_S4 is output as is as output signal _S6 . on the other hand,
When the level of the signal _S9 is "1", the level conversion circuit 36 outputs the level of the output signal _S6 as " ₁ " regardless of the level of the detection signal S4.

According to such a configuration, when the timer device controls the advance angle according to the characteristic curve portion having a positive slope in _FIG . The signal levels are the same. Therefore, when θ _a < θ _b , the level of the detection signal S ₄ and the output signal S ₆ becomes “1”, and the solenoid valve 18
The average opening degree becomes smaller, and the actual advance angle is further advanced and brought closer to the target advance angle value. When θ _a >θ _b , the advance angle becomes small and approaches the target advance angle value, and control is performed so that θ _a =θ _b .

On the other hand, when the timer device controls the advance angle according to the characteristic curve portion having a negative slope (in the case of l<l ₁ ), the output signal _S6 becomes "1" regardless of the detection signal _S4 . The stroke l increases and finally l
=l ₁ and θ=0. After l ₁ ≦l,
Advance angle control is always performed within this range.

In this embodiment, only the rotation signal _S1 is shown as an input signal for obtaining the target advance angle characteristic, but other signals such as load, temperature, etc. can be used as the control signal.

According to the present invention, it is possible to automatically determine the slope of the advance angle characteristic of a hydraulic timer from the position of the timer piston using a simple switch mechanism. , it is possible to stably perform advance angle control that matches the actual advance angle with the target.

[Brief explanation of the drawing]

Fig. 1 is a partial cross-sectional schematic diagram of a conventional hydraulic timer device, Fig. 2 is a front view of the driven side disc portion of Fig. 1, and Fig. 3 is the device shown in Fig. 1. Figure 4 is a schematic diagram of an embodiment of the present invention, Figure 5 is a block diagram of the control system of the device in Figure 4, and Figure 6 is shown in Figures 4 and 5. FIG. 3 is a characteristic diagram showing target advance angle characteristics of an embodiment. 1... Driven side shaft, 2... Driven side disk, 3... First
Eccentric cam, 4... Second eccentric cam, 5... Drive side disc,
6, 8...Pin, 7...Piston, 9...Cylinder, 1
1...Camshaft, 14...Hydraulic device, 18...Solenoid valve, 1
8a... Excitation coil, 30... Timer device, 31... Operation pin, 32... Switch, 33... Actual advance angle detector,
34...Target advance angle calculator, 35...Comparison circuit, 36...
Level conversion circuit, 37...Drive circuit, 38...Rotation detector, 40...Control device, S1...Rotation signal, _S2 ...Actual advance angle signal, _{S3 ...} Target advance angle signal, _S4 ...Detection signal, _S5 …
Pulse signal, _S6 , _S9 ...output signal.

Claims (1)

[Claims] 1. In a timer device for a fuel injection pump that has a hydraulic timer that connects the driven side and the driving side by an eccentric cam assembly and operates with an advance characteristic with a starting advance angle, the actual advance angle and the target a comparison means for detecting a difference between the advance angle of the hydraulic timer; a switch that is operated on/off according to the position of the piston of the hydraulic timer; The invention is characterized by comprising a converting means for inverting the comparative output from the comparing means in accordance with the output from the switch, and a driving means for adjusting the hydraulic pressure of the hydraulic timer based on the output from the converting means. Fuel injection pump timer device.