JPS6349062B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection timing adjustment device for a fuel injection device for an internal combustion engine.

BACKGROUND ART In diesel engines, such as automobile diesel engines, which have a wide range of rotations for normal use, it is necessary to change the fuel injection timing according to the operating conditions in order to obtain optimal engine performance. The device for this purpose is an autotimer. Conventionally, in the above-mentioned autotimer, the rotation of the drive shaft that transmits power from the engine is transmitted to the pump shaft for driving the injection pump via a flyweight disposed on the drive shaft, and the rotation of the drive shaft is transmitted to the pump shaft for driving the injection pump. The flyweight was configured to move in response to an increase in rotational speed to advance the pump shaft with respect to the drive shaft. In general, in order to obtain optimal engine performance in a diesel engine, it is sufficient to advance the fuel injection timing as the engine rotates at high speeds, so the conventional autotimer mentioned above fully fulfills its function in this regard. . However, when starting the engine, when the engine temperature is low and the fuel combustion speed slows down, it is necessary to advance the fuel injection timing, and when reducing nitrogen oxides contained in exhaust gas and reducing noise. Therefore, during idling and other times when it is necessary to retard the fuel injection timing, the fuel injection timing is neither advanced nor retarded.In other words, the fuel injection timing is set at a time that allows for a compromise between low-temperature startability and engine performance. As a result, there was a problem in that the low-temperature startability and engine performance were not fully satisfactory. Furthermore, since the conventional auto-timer described above uses a direct means of directly advancing the pump shaft by moving the fly weight of the rotational speed, it has the disadvantage that delicate adjustments are difficult.

In view of these points, the present invention detects the operating state of the engine using various sensor devices, operates a hydraulic piston in the axial direction, and uses the cooperative action of this piston and a slider that is in contact with it and moves in the radial direction. The rotation of the eccentric cam is adjusted by the axial movement of the hydraulic piston, making it possible to control the fuel injection timing more easily and reliably than the conventional flyweight method, and it is possible to control the fuel injection timing easily and reliably by adjusting the engine operating status and other factors. It is an object of the present invention to provide a fuel injection timing adjustment device that can always obtain the optimum fuel injection timing depending on the environment and conditions.

An embodiment of the present invention will be described below. FIG. 1 is an overall configuration diagram. Reference numeral 1 denotes an operating condition detector that detects the operating conditions of the engine, and signals such as engine speed and engine load can be considered. Reference numeral 2 denotes an electric control circuit which calculates the target injection timing based on the signal from the operating condition detector 1, compares it with the signal from the actual injection timing detector 6, and drives the pressure control valve 3 according to the error. . The hydraulic pressure adjusted by the pressure control valve 3 drives a hydraulic actuator 4 to adjust the injection timing of the injection pump 5.

2 and 3 show configuration diagrams of the hydraulic actuator 4. FIG.

In FIGS. 2 and 3, a rotating flange 10, which rotates synchronously with the drive side (engine), is integrated with a device cover 14 by means of fixing bolts 15, and together with the cover 14 forms a casing of the device. The cover 14 rotates while being in contact with the outer circumferential surface 13a of the cylindrical sleeve 13 formed on the fixed flange 12 coupled to the driven side (fuel injection device 5) or an external fixed part by the bolt 11. The driven rotor hub 16 is integrated into the rotary flange 10 and is connected by a nut 18 to the camshaft 17 of the injector.

The hub 16 has two sets of eccentric cams 33a and 33, large and small.
b is provided. The pair of sliders 19 have eccentric shaft pins 20 that support each set of large eccentric cams 33a, and the inclined surfaces 19a of the sliders 19 are arranged at the boss portion 1 of the hub 16.
6a and the inner surface 13b of the sleeve 13 as guide surfaces, a ring-shaped piston 21 slides in the axial direction.
is always in contact with the corresponding inclined surface 21a. The small eccentric cam 33b and the rotating flange 10 are connected to the eccentric shaft pin 3.
8. The slider 19 and the piston 21 each have at least one through hole 22, 23 for assisting the flow of lubricating oil and regulating oil within the device.
or more. That is, these through holes 22,
The presence of the piston 23 not only makes the flow of oil in the device smooth and reduces wear on various parts, but also makes the sliding of the piston 21 and the slider 19 (described later) smooth.

Furthermore, at least one hole 24 is formed in the piston 21, and a pin 27 having a corresponding cross-section is inserted into the hole 24 to form a pressure chamber 28. The pin 27 is integrated with the fixed flange 12,
It also has an oil passage 26b guided to the external gear pump 25. The oil passage 26b is connected to the gear pump 25 via an oil passage 26a formed in the fixed flange 12. As will be described later, the provision of these oil passages 26a and 26b facilitates the supply of hydraulic pressure for operating the piston 21. Further, an oil sump 29 is formed between the fixed flange 12 and the piston 21,
Excess oil is drained from this oil sump 29 to an external oil tank 30 via an oil passage 30 formed in the fixed flange 12.
lead to. The return spring 32 is connected to the slider 19
prevent the slider 19 from expanding in the circumferential direction.
is attached between both sliders 19 in order to urge the slope 19a of the piston 21 to contact the slope 21a of the piston 21. For example, an electromagnetic pressure control valve 3 is provided on the discharge side of the gear pump 25 to control the discharge pressure of oil. Electrical control circuit 2 controls control valve 3 based on the signal from operating condition detector 1 .

This signal can be, for example, the engine exhaust gas temperature.
T ₁ and rotation speed N, engine load R, outside air temperature T ₂ , outside air pressure P, outside air humidity, etc. can be considered, but in this embodiment, the rotation speed N and engine load R are detected by a sensor. A signal is input to the electrical control circuit 2. The electrical control circuit 2 calculates the target injection timing based on a preprogrammed instruction, compares it with the signal from the actual injection timing detector 6, outputs an instruction as an appropriate electric signal, and controls the pressure control valve. Controls the operation of 3. The constant pressure oil pumped by the gear pump 25 is adjusted to an appropriate pressure by the pressure control valve 3 and then transferred to the oil passage 26 provided in the fixed flange 12.
a, the oil passes through the oil passage 26b of the pin 27 and is sent to the pressure chamber 28 which becomes the hydraulic chamber. In this way, the pressure in the pressure chamber can be changed arbitrarily, and the piston 21 can be moved in the axial direction. When the piston 21 moves in the axial direction, the slider 19 is pushed up in the radial direction by the action of the inclined surface 21a of the piston and the inclined surface 19a of the slider 19. On the other hand, the slider 19 is rotated by the hub 16 via a pin 20 (the hub 16 itself is rotated by the rotating flange 16 via a pin 38).
), so in the end slider 1
9 moves in the radial direction while constantly rotating in contact with the piston 21. Eccentric cam 33a supported by pin 20 due to radial movement of slider 19
The eccentric cam 33b supported by the pin 38 rotates, and the rotating flange on the driving side and the hub on the driven side maintain an appropriate relative rotational phase while maintaining a balanced state by the action of the return spring 32 provided on the slider 19. This occurs and the injection timing is adjusted. Note that the axial movement of the piston 21 moves the slider 19 in the radial direction, and this slider 19 rotates the eccentric cam. Since this is done by motion, the device can be made smaller compared to, for example, a spline type.

In addition, in FIG. 1, 35a, 35b, 35
c, 35d shows an oil seal.

FIG. 4 is a diagram showing details of the electrical control circuit 2 of FIG. 1. Reference numeral 1a designates a rotational speed detector, which, as shown in FIG. 5, consists of gears 1a, 1 made of magnetic material attached to the pump drive shaft of the engine, and electromagnetic pick-ups 1a, 2 attached opposite to the gears. Consisting of 6 is an actual injection timing detector, which has the same structure as 1a and is attached to the camshaft of the pump. Signals from the rotational speed detector 1a and the actual injection timing detector 6 are input to the waveform shaping circuit 2c. 6th
The figure shows an example of the waveform shaping circuit 2c, which converts a signal input as a sine wave into a rectangular wave as shown in FIG. The pulse generation circuit 2d receives two rectangular wave signals shaped by the waveform shaping circuit 2c, and
This is a circuit that converts the rotation speed and actual injection timing into pulses that can be measured by the microcomputer 2a, and an example of the circuit is shown in FIG. A waveform-shaped signal from the rotational speed detector 1a is inputted to the A terminal in FIG. 8, and a waveform-shaped signal from the actual injection timing detector 6 is inputted to the B terminal in FIG. There is a hydraulic actuator 4 between the pump drive shaft from the engine and the pump camshaft, and the phases of the pump drive shaft and pump camshaft are twisted depending on the injection timing, and as a result, the rotation speed detector 1a and the actual The detection signal of the injection timing detector 6 has a phase difference depending on the injection timing. Therefore, at a certain injection timing, the A and B terminals in FIG.
Assume that signals 1 and 2 in the figure are input. Signals 3 and 4 in FIG. 9 are output to output terminals C and D. This is input into the microcomputer 2a to measure the rotational speed and actual injection timing.

Reference numeral 1b in FIG. 4 is a rack position detector, which detects the load of the engine at the rack position and adjusts the injection timing.

In this embodiment, a variable inductance type is used, and its structure is shown in FIG. A primary coil 10b and a secondary coil 10a are wound around a hollow bobbin 10c. A core 10d is inserted into the hollow part. When an excitation signal of constant amplitude and constant frequency is applied to the primary coil 10b, if the secondary coil 10a is terminated with a resistor, a voltage is generated across the resistor. Now, assuming that the length of the portion where the core 10d inserted into the hollow part overlaps with the secondary coil 10a is l, the relationship between the voltage V _PP generated at both ends of the secondary coil and l is shown in Figure 11. Become something. The detector of this embodiment utilizes the linear portion of this characteristic. FIG. 12 shows a circuit related to the rack position detector 1b;
That is, the detection circuit 2e and the oscillation drive circuit 2f. In this figure, 121 to 125 constitute oscillation drive circuits, and 126 to 129 constitute detection circuits. A constant voltage section 121 is a circuit for supplying a constant offset voltage to each amplification stage, and is composed of a resistive voltage dividing circuit and a buffer amplifier. 122,1
23 is a quadrature oscillation circuit, 124 is a buffer amplifier, and 125 is a current amplifier. Note 12
2 is the oscillation part of the quadrature oscillation circuit; 12
3 is an amplitude limiting circuit that limits the amplitude of the oscillation waveform of the oscillator. The detection circuit includes a capacitor 126 that cuts off the DC component, a full-wave rectifier circuit 127, and an integrating circuit 1.
28 and a differential amplifier circuit 129.
The output signal V _R of the differential amplifier circuit 129 becomes the rack position signal.

2g in FIG. 4 is an A/D converter, which is the detection circuit 2.
The analog rack position signal from e is converted into digital and input to the microcomputer 2a.

The microcomputer 2a is an 8-bit one-chip microcomputer with internal ROM,
It includes RAM, timer functions, etc.

The drive circuit 2b amplifies the output signal from the microcomputer 2a to drive the pressure control valve 3. The pressure control valve 3 has a hydraulic inflow side,
One valve is provided on each outlet side, and a computer controls the opening time of each valve to control oil pressure and injection timing.

Next, the operation of the computer 2a section will be explained based on the flowchart of FIG. First step 1
At step 30, the internal memory and input/output ports of the computer are set to the initial state. Step 1
At step 31, the engine speed is calculated based on the data obtained at interrupt routine steps 137-139.
Next, in step 132, the rack position signal is input through the A/D converter 2g. Next step 1
At step 33, the target injection timing is calculated from the engine speed obtained at steps 132 and 133 and the rack position. The target injection timing is calculated by storing a map using the engine speed and rack position as parameters in the ROM in the microcomputer 2a, and performing four-point interpolation. An example of the map is shown in FIG. In this case, the horizontal axis represents the engine speed and the vertical axis represents the easy position, and the grid point where the engine speed is No _and the easy position is R _n is associated with the target injection timing t _on . A method for determining the target injection timing t from this map will be explained using an example. engine rotation speed
Suppose N _x and the rack position is R _x , these values are
It is assumed that N _a <N _x < N _b and R _a < R _x < R _b , respectively.
The target injection timing at the current point (N _a , R _a ) is t=t _aa ,
t=t _ab at the point (N _a , R _b ), t=t _ba at the point (N _b , R _a ),
Assume that t=t _bb at the point (N _b , R _b ). The procedure for determining the target injection timing t at the point (N _x , R _x ) under these conditions using the four-point interpolation method will be explained using FIG. 16. First, the target injection timing _txa at the point (N _x , R _a ) is determined using the following equation.

t _xa =N _x -N _a /N _b -N _a × (t _ba - t _aa ) + t _aa Next, the target injection timing t _xb at the point (N _x , R _b ) is determined by the following equation.

t _xb = N _x - N _a / N _b - N _a (t _bb - t _ab ) + t _ab Finally, the target injection timing t _xx at the point (N _x , R _x ) is determined using the following formula.

t _xx =R _x −R _a /R _b −R _a (t _xb −t _xa )+t _xa The target injection timing can be determined using a series of formulas such as the above. In step 134, the actual injection timing is calculated based on the data obtained in steps 137-139 of the interrupt routine. Step 13
In step 5, the target injection timing obtained in step 133 and the actual injection timing obtained in step 134 are compared. In step 136, the opening times of the pressure control valves on the inflow and outflow sides of the hydraulic pressure are determined according to the difference between the actual injection timing and the target injection timing obtained in step 135, and an output pulse is sent to the drive circuit 2b. put out. While repeating the above, a pulse like 3 in Figure 9 is output to the C terminal in Figure 8, and when the computer 2a detects the rising edge of the pulse, the program goes to the interrupt routine in Figure 13. Move. In the interrupt routine, first, in step 137, the value of the free running counter built into the computer at that time is read. Then step 138
It is checked whether terminal D is 1 or 0, and if it is 1, in step 139 the value of the free running counter read in step 137 is stored in the memory address for writing injection timing data. If the terminal D is 0, in step 139, the value of the free running counter read in step 137 is stored in the memory address for writing rotation speed data. After performing the above operations, the program returns to the main routine and performs normal calculations.

Next, the operation of the fuel injection timing adjustment device described above will be explained.

Now, the engine speed is N ₁ (rpm) and the easy position is
Suppose you are driving in _R1 . Assume that the pump camshaft advance angle at that time is θ (°). From the rotation speed detector 1a, a sine wave with a frequency proportional to the rotation speed _N1 is input to the waveform shaping circuit 2c, and the rotation speed is
It is converted into a pulse train (FIG. 9 1) with a frequency proportional to N ₁ and input to the pulse generation circuit 2d. On the other hand, the output of the actual injection timing detector 6 has a frequency equal to that of the rotation speed detector 1a, and becomes a sine wave with a phase time difference t ₁ according to the advance angle θ (°), and is processed by the waveform shaping circuit 2c as shown in FIG. The pulse train is input to the B terminal of the pulse generation circuit 2d. Normally, the camshaft is twisted more to the advance side than the drive shaft, so the B terminal is more sensitive than the A terminal as shown in 1 and 2 in Figure 9.
A pulse is input t ₁ earlier. At the same time that the pulse is input to the B terminal, the terminal C receives the signal 3 in Fig. 9.
A pulse such as P ₁ is output. When the microcomputer 2a receives this pulse _P1 , it executes the interrupt routine shown in FIG. 13, and in step 137 reads the timer value _T1 . Next, in step 138, the state of terminal D is checked; at this time, terminal D is 1, as shown at 4 in FIG.
Therefore, the read timer value _T1 is stored in the injection timing data memory address _Ao . Next, after time _t1 , when a pulse is input to the A terminal and at the same time a pulse _P2 is generated from the C terminal, the microcomputer 2a again executes the interrupt routine in FIG. 13 and reads the timer value _T2 in step 137. . When the state of the D terminal is checked at step 138, it is 0 as shown at 4 in FIG. 9, so it is stored in the rotational speed data memory address B _o . From terminal C below,
When pulses P ₃ and P ₄ are output, the timer values T ₃ and T ₄ at that time are stored in A _o+1 and B _o+1 , respectively. After the steps in the interrupt routine are completed,
The main routine steps are repeated until the next interrupt occurs. Step 13
1, read data T ₂ and T ₄ from rotation speed data memory addresses B _o and B _o+1 , calculate N ₁ = K ₁ / (T ₄ − _{T 2} ) K ₁ : constant, and read rotation speed data. demand.

Next, in step 132, the A/D converter 2g
Then, read the rack position data _R1 . In step 133, a map search and four-point interpolation are performed using the data N ₁ and R ₁ to calculate the target advance angle time t' ₁ . Next, in step 134, data is stored from injection timing data memory address A _o and rotational speed data address B _o .
Read T ₁ and T ₂ and calculate t ₁ = T ₂ − _{T 1} to obtain actual injection timing data.

In step 135, t ₁ and t' ₁ are compared, and Δt=t ₁
−t′ ₁ is calculated as the error time. Step 13
6, if Δt>0, Δt<0 in the retarding direction
If so, an output signal is output to the drive circuit 2b so that the hydraulic actuator moves in a direction that advances the angle more, and so that the hydraulic control valve opens for a time corresponding to |Δt|.

By repeating the above steps, the adjustment is always made so that the optimum injection timing is achieved.

In this example, we have explained how to calculate the target injection timing from a map that determines the time difference between the drive shaft rotation angle detection signal and the camshaft rotation angle detection signal. It is also possible to calculate the target injection timing by calculating the rotational phase angle θ=KNt of the camshaft and from a map of the target phase angle. FIG. 17 shows an example of a target injection timing map. Furthermore, in the embodiment described above, the injection timing was detected based on the rotational phase difference between the pump drive shaft of the engine and the camshaft, but as shown in FIG. As a result, the position of the magnetic material 142 changes, and the inductance of the coil 141 changes in accordance with the change. This can be detected by a known inductance change detection circuit to detect the opening timing of the nozzle. If this signal is used as the actual injection timing signal, the injection timing can be adjusted using the same configuration except for the above. As described above, according to the present invention, the hydraulic pressure in the hydraulic chamber is controlled to move in the axial direction the hydraulically driven piston that supports the eccentric cam that adjusts the injection timing and is in contact with the slope of the slider that is movable in the radial direction. Therefore, the rotation of the eccentric cam can be easily adjusted by the axial movement of the piston, and the piston is controlled so that the actual injection timing approaches the target injection timing calculated from the engine load and rotation speed. It becomes possible to easily and reliably fine-tune the injection timing to match the operating conditions, and it becomes possible to improve the accuracy of injection timing feedback control.

[Brief explanation of the drawing]

Fig. 1 is an overall block diagram of the device of the present invention, Figs. 2 and 3 are block diagrams of the hydraulic actuator, Fig. 4 is a block diagram of the control circuit of Fig. 1, and Fig. 5 is a block diagram of the control circuit of Fig. 4. 6 is an electric circuit diagram showing the waveform shaping circuit of FIG. 4; FIGS. 7a and b are diagrams showing the input waveform and output waveform of the waveform shaping circuit of FIG. 6; 8 is an electric circuit diagram of the pulse generation circuit of FIG. 4, FIG. 9 is a waveform diagram showing the input waveform and output waveform of the pulse generation circuit of FIG. 8, and FIG. Figure 4 is a cross-sectional view of the rack position detector, Figure 11 is a diagram showing the relationship between the core insertion length and generated voltage in Figure 10, and Figure 12 is an electric circuit diagram of the detection circuit and oscillation drive circuit in Figure 4. , 1st
FIG. 3 is a flowchart related to the microcomputer in FIG. 4, FIG. 14 is a diagram showing another example of the actual injection timing detector, and FIG. 15 is a map showing the target injection timing corresponding to the engine speed and the rack position. ,
FIG. 16 is an explanatory diagram when the target injection timing is determined by the four-point interpolation method, and FIG. 17 is a map showing the target injection timing in another embodiment. 1... Operating condition detector, 2... Electric control circuit, 3... Pressure control valve, 4... Hydraulic actuator, 6... Actual injection timing detector.

Claims (1)

[Scope of Claims] 1. An eccentric cam that adjusts the rotational phase between a camshaft and a drive shaft of a fuel injection device to adjust fuel injection timing, and an eccentric cam that supports this eccentric cam and moves in a radial direction. A slider that rotates the slider; A hydraulically driven piston that has an inclined surface formed at a contact portion of the slider and that moves in the axial direction while making sliding contact with the slider to move the slider in the radial direction; urging means for urging the slider into contact with the slope of the drive shaft; rotation speed detection means for detecting the rotation speed of the drive shaft; load detection means for detecting engine load; target injection timing calculation means for calculating a target injection timing of the fuel injection device from the engine load and rotation speed detected by the rotation speed detection means; and an actual injection timing for detecting the actual injection timing of the fuel injection device. an actual injection timing calculation means for calculating an actual injection timing from signals from the detection means and the rotational speed detection means; and an actual injection timing and a target injection timing calculated by the actual injection timing calculation means and the target injection timing calculation means. an electro-hydraulic fuel injection timing adjustment device, comprising means for electrically controlling the hydraulic pressure within the hydraulic chamber for moving the hydraulically driven piston in the axial direction according to the difference between the hydraulically driven piston and the hydraulically driven piston. 2. The fuel injection timing adjustment device according to claim 1, wherein the actual injection timing detection means includes a camshaft rotational position detector provided on the camshaft. Timing adjustment device. 3. The electro-hydraulic fuel injection timing adjustment device according to claim 2, wherein the actual injection timing detection means includes means for detecting valve opening movement of the injection nozzle. . 4. In the electro-hydraulic fuel injection regulating device according to claim 1, 2 or 3,
An electro-hydraulic fuel injection timing adjustment device, wherein the load detection means includes means for detecting a position of a fuel adjustment member of the fuel injection device.