JPH025078Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an injection amount control device for controlling the amount of fuel injected in a fuel injection pump of a diesel engine.

Conventionally, as an injection amount control device for a fuel injection pump of a diesel engine, there is a device as shown in Figs. 1 and 2 (Japanese Patent Publication No. 55-31307).
(see publication).

As shown in FIG. 2, this distribution type fuel injection pump 1 is operated by the rotation of a cam disk 2 connected to the drive shaft of the engine, and is operated to reciprocate in the axial direction for sucking and pumping fuel and for distributing fuel. It has a plunger 3 that performs rotational movement.

In the suction stroke by the plunger 3, when the plunger 3 moves to the left in FIG. 2, the suction vertical groove 4 aligns with the fuel inflow passage 5, and fuel is sucked into the pressurizing chamber 6.

During the discharge stroke, the plunger 3 begins to move to the right, but at this time, the suction vertical groove 4 and the fuel inflow passage 5 are out of alignment, so the fuel in the pressurizing chamber 6 is pressurized.
When the discharge lateral groove 8 coincides with the discharge passage 9 through the vertical passage 7, the fluid is discharged through the check valve 10 to an injection valve of a cylinder (not shown).

And the fuel relief passage 1 provided in the plunger 3
1 is located on the right side of the sleeve 12, which is a cylindrical valve body, pressurized fuel flows through the fuel relief passage 1.
1 and escapes into the space inside the pump casing, pressurization ends and fuel discharge ends.

The mechanism for operating the sleeve 12, which determines the amount of fuel injection, consists of an electromagnet having two coils 14 and 15 wound around an iron core 13 having a cylindrical gap, and a rotary shaft 16 that moves the coils 16 and 15 outward in the gap. A rotating permanent magnet 18 rotatably supported by the housing 17
It is composed of.

A fan-shaped piece 19 is attached eccentrically to the lower end of the rotating shaft 16, and a spherical engagement piece 20 fixed eccentrically from the central axis of the fan-shaped piece 19 is attached to the sleeve 12.
The sleeve 12 is fitted in the hole 21 so that the rotational motion of the rotating permanent magnet 18 is transmitted to the sleeve 12 and displaced in the axial direction.

The electromagnetic coils 14, 15 are connected to the output of a control device 23 via an amplifier 22, as shown in FIG.

The control device 23 includes various operating parameters indicating the operating conditions of the internal combustion engine, such as an engine rotational speed signal from a rotational speed sensor 25, an accelerator pedal position signal from an oscillator 26, and other intake pipe negative pressure (not shown). , a signal related to engine temperature or ambient temperature, etc. is given as an input, and a current corresponding to these operating parameters is supplied via an amplifier 22, and the rotating permanent magnet 18 is rotated with an operating force corresponding to this. .

The rotation sensor 25 is arranged opposite to a toothed disc 24 attached to the drive shaft of the engine, and generates a voltage in proportion to the engine rotation speed from an induction coil 25b wound around a magnet 25a, and controls it. input to the device 23;

Further, the position sensor 27 that generates a feedback signal for controlling the position of the sleeve 12 does not directly detect the displacement of the sleeve 12, but converts the rotation of the rotating permanent magnet 18 into a linear displacement of the ferrite magnetic core 27a. It is indirectly detected by two inductance coils 27b and 27c supplied with power from the oscillator 28.

In this way, in the conventional fuel injection pump 1, the injection amount is indirectly controlled by controlling the position of the sleeve 12 that closes the fuel relief passage 11 of the plunger 3 according to the operating parameters of the engine. I was doing it.

However, the positional accuracy of the fuel relief passage (cut-off port) 11 of the plunger, the sleeve 12
Due to the dimensional accuracy of the plunger 3, the thickness accuracy of the adjustment shim of the plunger 3, etc., it is difficult to make the relative position of the sleeve and cutoff port, which determines the injection amount, constant for all products.

Therefore, it is necessary to calibrate the injection amount for each fuel injection pump using a testing device, and there is also the problem that the injection amount cannot be corrected for changes over time.

Therefore, as seen in, for example, JP-A-57-32026 and JP-A-57-32024, in order to eliminate the influence of changes over time, the fuel injection time is determined based on the pressure detection result of the pressurizing chamber. It has also been proposed to perform feedback correction on the control sleeve position control mechanism using a signal with a corresponding pulse width or by detecting the amount of lift of the plunger.

However, in these cases, the fuel injection amount is controlled by the control sleeve and its position control mechanism, similar to the conventional example described above.
This does not solve the problem of being affected by play in the links of the position control mechanism, position servo control errors, and the like.

Furthermore, in order to perform feedback control, it is necessary to consider the stability of the control system.
A problem arises in that the design becomes difficult.

For example, in the former case, if a certain injection nozzle enters a failure mode where the pressure does not rise sufficiently, the injection amount will be corrected for the next injection (a normal nozzle in another cylinder). For,
There is a problem in that the effects of failure are amplified.

In the latter case, there is a problem of poor productivity because it is necessary to adjust and measure the injection amount and store the reference value of the plunger lift amount in the nonvolatile memory of the controller when producing the injection pump.

This idea was made in view of these problems, and it is possible to always accurately control the fuel injection amount regardless of the processing accuracy, assembly accuracy, aging, etc. of the fuel injection pump, and it has a simple structure and design. It is an object of the present invention to provide an injection amount control device that is easy to use, has good stability, and can improve productivity.

Therefore, the fuel injection pump injection amount control device according to this invention is based on the position of the plunger at the time when the fuel pressurized by the plunger starts to be discharged, and the injection amount that corresponds to the injection amount calculated based on the engine operating conditions. The plunger position at the end of discharge is calculated based on the stroke length, and when the target position of the plunger, which is the calculation result, matches the current position of the plunger, the fuel relief passage is opened and the discharge of fuel is ended. Therefore, the injection amount is controlled.

Hereinafter, embodiments of this invention will be described with reference to FIG. 3 and subsequent figures of the accompanying drawings. Note that portions corresponding to those in FIGS. 1 and 2 are designated by the same reference numerals, and explanations of those portions will be omitted.

FIG. 3 is a schematic configuration diagram showing an example of an injection charge control device for a distribution type fuel injection pump implementing this invention.

In the same figure, the fuel relief passage 1 of the plunger 3
A cylindrical magnet 31 is fixed to a sleeve 12 which is a valve body that opens and closes the valve body 1, and the magnet 31 is wound around the outer periphery of the magnet 31 so as to face each other at a distance so that the same polarity occurs in adjacent parts. cylindrical drive coils 32, 32 are arranged, and this drive coil 32
A yoke 33 that serves both as a magnetic path and a coil protector surrounds the circumferential surface of the yoke 33 to constitute passage opening/closing means for opening and closing the fuel relief passage 11.

Further, a position sensor 34 for directly detecting the displacement of the plunger 3 in a non-contact manner is placed in a groove 3a formed in the plunger 3 on a support member 3 fixed to the yoke 33.
3a. The distance between the side of the groove 3a of the plunger 3 and the position sensor 34 is determined by adding a clearance to the stroke (1.5 to 2.2 mm) of the plunger 3.

This position sensor 34 generates an alternating magnetic field from an internal primary coil to generate an eddy current on the side of the groove 3a of the plunger 3, detects the eddy current with a secondary coil, and uses the detection signal to detect the position. Output to circuit 35.

This position detection circuit 35 detects the current position of the plunger 3 based on the output signal of the position sensor 34, and outputs a position detection signal _S1 according to the detection result.

These position sensors 34 and position detection circuits 35
The plunger position detecting means for detecting the plunger position is constituted by the plunger position detecting means.

Further, a pressure sensor 36 for detecting the fuel pressure in the pressurizing chamber 6 is provided on the back wall of the pressurizing chamber 6, and an output signal corresponding to the fuel pressure of the pressure sensor 36 is input to a discharge start timing detection circuit 37. do.

The discharge start timing detection circuit 37 detects pressurization by comparing the pressure corresponding to the output signal of the pressure sensor 36 with a predetermined pressure (injection valve opening pressure 100 to 150 Kgf/cm ² ). It is determined whether or not fuel discharge (injection) has started, and a discharge start signal _S2 is output when discharge of pressurized fuel has started.

The pressure sensor 36 and the discharge start time detection circuit 37 constitute a discharge start time detection means for detecting the discharge start time of the pressurized fuel.

The discharge termination control circuit 38 includes an input section that inputs various signals, an output section that outputs a drive signal for the drive coil 32 to the drive circuit 39, and a calculation section that calculates and compares the fuel injection amount and the target value of the plunger 3. , a storage section that stores calculated values, etc., and a control section that controls each of these sections.

The discharge end control circuit 38 receives a position detection signal _S1 from the position detection circuit 35, a discharge start signal _S2 from the discharge start timing detection circuit 37, an engine rotation speed signal _S3 , and an accelerator pedal depression signal S. _4. Input various signals indicating engine operating conditions such as the temperature signal _S5 , calculate the target position of the plunger 3 at the end of discharge based on these input signals, and calculate the target position of the plunger 3 and the current position. When the positions match, a current is applied to the drive coil 32 via the drive circuit 39 to excite it, and the sleeve 12, which is integrated with the magnet 31, is moved to the left in FIG.

In addition, 40 in the figure is a roller, and this roller 4
The relative phase angle between the roller 40 and the cam disc 2 is determined by an advance mechanism (not shown).
The fuel injection timing is controlled by changing the displacement in the circumferential direction.

Next, the operation of the embodiment configured as described above will be explained.

First, in the discharge process, as in the conventional case, when the roller 40 rides on the face cam 2a due to the rotation of the cam disc 2, the plunger 3 moves to the right in FIG. The pressurized fuel is discharged through the vertical passage 7 to the injection valve (not shown) when the discharge groove 8 coincides with the discharge passage 9, and the pressure reaches the opening pressure of the injection valve (100 to 150 Kgf/cm ² ). Once reached, injection begins.

This change in fuel pressure in the pressurizing chamber 6 is detected by the pressure sensor 36, and a discharge start signal _S2 is output from the discharge start timing detection circuit 37 to the discharge end control circuit 38 at the start of fuel discharge (injection start). be done.

Therefore, when the discharge start signal S ₂ is input, the discharge end control circuit 38 uses the position detection signal S ₁ from the position detection circuit 35 to adjust the position of the plunger 3 at that time.
In addition to detecting the position of the engine speed signal S ₃
The optimum fuel injection amount is calculated based on the signal indicating the operating conditions of the engine, etc., the stroke length of the plunger 3 corresponding to this injection amount is calculated, and the plunger position at the discharge start time and this stroke length are added. Then, the plunger position (target position) at the end of discharge is calculated.

Note that since the injection amount is determined by the product of the effective stroke length of the plunger 3 and its cross-sectional area, the effective stroke length is determined by the injection amount/cross-sectional area.

When the target position of the plunger 3 and the current position of the plunger 3 indicated by the position detection signal _S1 from the position detection circuit 35 match, the discharge end control circuit 38 is driven via the drive circuit 39. A current is passed through the coil 32 to excite, for example, adjacent parts as N poles and both ends as S poles, as shown in the figure.

As a result, the north pole of the magnet 31 attracts the south pole of the drive coil 32 on the left side, and the south pole repels the south pole of the drive coil 32 on the right side, so that the sleeve 12 integrated with the magnet 31 Since the fuel relief passage 11 is opened by moving to the left in the figure, the pressurized fuel escapes into the space inside the pump casing through the fuel relief passage 11, and the discharge of fuel is completed.

Although the plunger 3 moves to the right after the discharge is completed, the fuel is not pumped out because the fuel relief passage 11 is open.

When it is detected that the plunger 3 has reached the top dead center (rightward limit), the drive coils 32, 32
With the current flowing in the opposite direction, the adjacent parts are connected to S.
The pole and both ends are excited to the N pole, and the sleeve 12 is moved to the right to close the fuel relief passage 11. Thereby, the sleeve 12 is located on the right side in the figure during the intake stroke.

In this manner, when the plunger 3 moves to a position where the amount of fuel to be injected is obtained in accordance with the operating conditions of the engine, the sleeve 12 is displaced to open the fuel relief passage 11 and end the discharge of fuel.

Therefore, the sleeve 12 and the fuel relief passage 11
The injection amount can be accurately controlled regardless of the relative positional accuracy between the fuel injection pump and the fuel injection pump, and regardless of the influence of aging, and there is no need to calibrate each fuel injection pump.

FIG. 4 is a schematic configuration diagram similar to FIG. 3 showing another embodiment of the present invention.

In this embodiment, a fuel escape passage 41 is formed on the inner wall surface of the pressurizing chamber 6 and is communicated with the fuel inflow passage 5 via a fuel return passage 42.

A valve body 43 is inserted into this fuel relief passage 41 and a piezoelectric laminate 44 that moves this valve body 43 is provided, and the fuel relief passage 41 is opened and closed by this valve body 43 and piezoelectric laminate 44. It constitutes an opening/closing means.

When a high voltage (400 to 500 V) generated by a high voltage generator (DC-DC converter) incorporated in the drive circuit 39 is applied to the electrodes, the piezoelectric laminate 44 has a long life due to dielectric polarization. Then, the valve body 43 is pushed against the valve seat and the fuel relief passage 41 is closed.

Furthermore, when the electrode of the piezoelectric laminate 44 is grounded,
The accumulated charge is released and contracts, moving the valve body 43 to the right and opening the fuel relief passage 41.

Therefore, this piezoelectric laminate 44 is driven and controlled by the discharge end control circuit 38, and in the suction step, a high voltage is applied to the electrodes of the piezoelectric laminate 44 to close the valve body 43. The valve is closed, and when the target position and the current position of the plunger 3 coincide in the discharge process, the electrode of the piezoelectric laminate 44 is connected to ground, the valve body 43 is opened, and the fuel relief passage 41 is opened. Then, when the plunger 3 moves to the top dead center, the valve body 43 is closed again to prepare for the next suction stroke.

In this embodiment, the plunger position detecting means for detecting the position of the plunger 3 is a pair of plunger position detecting means arranged on both sides of the flange portion 3b formed on the plunger 3.
position sensors 34a, 34b and position detection circuit 3
5, and two position sensors 34a,
By using a bridge configuration using 34b, changes in sensor characteristics due to temperature are canceled out, and detection accuracy is improved.

Note that the two position sensors 34a and 34b are mounted on a support member 4 fixed to the plunger housing 17a.
It is supported by 6. Further, the pressure sensor 36 is embedded in the circumferential surface of the pressurizing chamber 6.

The configuration and operation of the other parts are the same as those of the embodiment shown in FIG. 3 described above, so the explanation thereof will be omitted.

In each of the above embodiments, an example was described in which the fuel relief passage 41 is closed at the top dead center of the plunger 3 (the right-hand end in the figure). If it closes when it reaches the dead center (left end in the figure), the pressurized chamber 6
The fuel is inhaled through the vertical passage 7, and the suction vertical groove 4 can be omitted, reducing production costs.

As explained above, according to this idea,
In the fuel injection pump for a diesel engine, the control accuracy of the fuel injection amount has been improved, and the fuel injection amount can always be accurately controlled without being affected by the machining and assembly accuracy of the plunger mounting position, etc., or changes over time.

In addition, there is no need to provide a control sleeve whose position is controlled with high precision and a position control mechanism that uses a link mechanism or position servo control circuit to move it, as in the past, so the structure is simple and the link mechanism is simple. This eliminates the influence of backlash and position servo control errors.

Furthermore, since feedback control is not performed, there is no need to consider the stability of the control system, which simplifies the design, and there is no need to measure the reference value of the plunger lift amount in advance and store it in memory. Therefore, productivity is also good.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are a configuration diagram and a longitudinal cross-sectional view of an essential part of an example of a conventional injection amount control device for a distribution type fuel injection pump. FIG. 3 is a schematic diagram showing one embodiment of this invention, and FIG. 4 is a schematic diagram showing another embodiment of this invention. 2...Cam disc, 3...Plunger, 6...
...Pressure chamber, 11, 14...Fuel relief passage, 12...
...Sleeve, 31...Magnet, 32...Drive coil, 33...Yoke, 34, 34a, 34b
...Position sensor, 35...Position detection circuit, 36...
...Pressure sensor, 37...Discharge start timing detection circuit,
38... Discharge end control circuit, 39... Drive circuit,
40...roller, 43...valve body, 44...piezoelectric laminate.

Claims (1)

[Scope of utility model registration request] In a fuel injection pump for a diesel engine, plunger position detection means detects the position of a plunger that pressurizes fuel; discharge start timing detection means detects a discharge start timing of fuel pressurized by the plunger; a passage opening/closing means for opening and closing a fuel relief passage to release the fuel pressurized by the pump; and a fuel injection amount calculated based on the detection results of the plunger position detection means and the discharge start timing detection means and the operating conditions of the engine. The plunger position at the end of discharge is calculated based on the corresponding stroke length of the plunger, and when the target position of the plunger, which is the calculation result, matches the position detected by the plunger position detection means, the passage opening/closing means is activated. An injection amount control device for a fuel injection pump, comprising: a discharge end control means that is driven to open the fuel relief passage.