JPH0979075A - Fuel injection control device for diesel engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve rotational stability by setting a target rotational speed to the highest rotational speed or higher of rotational speeds in a plurality of cylinders, in an operating region of relatively low engine speed where the rotational stability is considered important more than a control speed, of engine operating regions controlled to be classified by the cylinder. SOLUTION: During operation of a Diesel engine, in a control unit 60, in an operating region of relatively low engine speed where rotational stability is considered important, a target rotational speed is set to the highest rotational speed or higher of rotational speeds of four cylinders so that control of a fuel injection amount in each cylinder comes to be increasing control by turning a rotor 23 with a drive current flowing in a drive coil of an electronic governor 22. In an operating region of relatively high engine speed where a control speed is considered important, the rotor 23 is turned by a return spring, so as to obtain decreasing control, the target rotational speed is set to the lowest rotational speed or lower of rotational speeds of the four cylinders.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a fuel injection control device for a diesel engine.

[0002]

2. Description of the Related Art Generally, in a multi-cylinder diesel engine,
A distribution type fuel injection pump that distributes pressurized fuel is provided to the fuel injection nozzles of each cylinder, and an electronic governor included in the fuel injection pump is operated by a control signal from the control unit to operate the fuel injection pump. The fuel injection amount is controlled by moving the control sleeve of the vehicle back and forth.
1989).

By the way, in a diesel engine, even if the control unit instructs the same injection amount to the fuel injection pump, the fuel injection amount varies due to fluctuations in the fuel injection pump and individual differences in the fuel injection nozzle. Since engine vibration occurs due to this variation in injection amount, in order to reduce this vibration, control that attempts to correct injection variation for each cylinder in a constant rotation operation region of 1500 rpm or less including the idle rotation region (hereinafter , "Cylinder control") is generally performed.

As the calculation method currently used in this cylinder-by-cylinder control, (1) the number of revolutions of each cylinder is calculated (2) the deviation from the target number of revolutions is determined, and to what extent the next injection amount is corrected. The method of calculating or is generally used.

Here, the rotation speed for each cylinder is obtained from the angular velocity that increases during combustion of each cylinder, and the target rotation speed is, for example, the average value of the rotation speeds of all the cylinders.

[0006]

By the way, the electronic rotary governor generally used in the fuel injection pump of the diesel engine is constructed so that the servo mechanism operates when increasing the fuel injection amount, and therefore it is precise and accurate. Although stable control can be performed, it has the characteristic of slow response. On the other hand, when the fuel injection amount is reduced, the rotor of the electronic governor is designed to return with the elastic force of the return spring, so the control speed is fast and the response is good, but if the rotor returns with the elastic force of the return spring at a stroke, There is a problem that hunting occurs and the stability is poor. When the target rotation speed is set to the average value of the rotation speeds of all cylinders as in the conventional case, the overall response of the electronic governor is slow, so the governor constantly moves to control the fuel injection amount. This is not preferable.

The present invention provides a fuel injection control device for an engine of a diesel engine capable of performing optimum cylinder-by-cylinder control in accordance with the operating state at that time in consideration of the characteristics of the electronic governor as described above. The purpose is to do.

[0008]

In a fuel injection control device for a diesel engine according to the present invention, one of an increase amount and a decrease amount of a fuel injection amount from a fuel injection nozzle provided in each of a plurality of cylinders is a servo mechanism. By
A fuel injection pump provided with an electronic governor that performs the other by the elastic force of a spring, and the electronic governor is controlled in a predetermined engine operating region to control the fuel injection amount from the fuel injection nozzle of each cylinder to the rotation speed of the cylinder. In a fuel injection control device for a diesel engine having a cylinder-by-cylinder control means for correcting the cylinder-by-cylinder based on a rotation deviation between the target rotation speed and In an operating region where the rotation speed is relatively low, the target rotation speed is set so that the servo mechanism operates.

The "operating region in which the engine speed is relatively low" means, for example, a normal idle rotational region around 700 rpm.

When the electronic governor is constructed so that the fuel injection amount is increased by the servo mechanism and the fuel injection amount is decreased by the elastic force of the spring, the engine rotational speed is relatively low. In the region, the target rotation speed is set to the maximum rotation speed or higher of the rotation speeds of the cylinders.

In that case, of the engine operating range in which the cylinder-by-cylinder control means performs the cylinder-by-cylinder control,
In the operating region where the engine speed is relatively high, the target speed is set to the minimum speed or lower among the speeds of the cylinders.

The above-mentioned "operating range in which the engine speed is relatively high" is, for example, 12 higher than the normal idle speed range.
It means an operating range of about 00 to 1500 rpm.

Further, in the fuel injection control device for a diesel engine according to the present invention, one of the increase and decrease of the fuel injection amount from the fuel injection nozzle provided in each cylinder of a plurality of cylinders is performed by a servo mechanism, A fuel injection pump provided with an electronic governor that performs the other by the elastic force of a spring, and the electronic governor is controlled in a predetermined engine operating region to control the fuel injection amount from the fuel injection nozzle of each cylinder to the rotation speed of the cylinder. In a fuel injection control device for a diesel engine having a cylinder-by-cylinder control means for correcting the cylinder-by-cylinder based on a rotation deviation between the target rotation speed and In the operating range where the rotation speed is relatively high, the target rotation speed is set so that the elastic force of the spring acts. And it is characterized in Rukoto.

When the electronic governor is constructed so that the fuel injection amount is increased by the servo mechanism and the fuel injection amount is decreased by the elastic force of the spring, the operation at a relatively high engine speed is performed. In the region, the target rotation speed is set to the minimum rotation speed or lower than the rotation speed of each cylinder.

[0015]

According to the present invention, in the engine operating range in which the cylinder-by-cylinder control is performed, the operating range in which the engine speed is relatively low, where rotation stability is more important than control speed, such as the normal idle rotation range. Since the target rotation speed is set so that the servo mechanism of the electronic governor operates and the cylinder-by-cylinder control is performed, it is possible to improve the rotation stability and prevent hunting.

Further, in the engine operating range in which the cylinder-by-cylinder control is performed, an operating range in which the engine speed is relatively high, where control speed is more important than rotational stability, for example, engine speed is higher than the normal idle speed range. In the range, since the target rotation speed is set so that the cylinder-by-cylinder control is performed by the action of the elastic force of the spring of the electronic governor, quick control becomes possible.

In this case, the fail safe function can be provided by configuring the electronic governor so that the fuel injection amount is reduced by the elastic force of the spring.

[0018]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a functional configuration of a control unit of a fuel injection control device for a diesel engine according to the present invention. An operation status detecting unit 101, a target rotation speed switching unit 102, and a cylinder-specific control unit 103. It is composed of and.

The operating condition detector 101 detects the operating condition of the engine from the vehicle speed, the engine speed, the accelerator opening, the engine water temperature, the shift position of the transmission, and the like. The target rotation speed switching unit 102 detects the rotation speed of each cylinder from the engine rotation speed and the cylinder pulse, and sets the target rotation speed to the maximum rotation speed of the rotation speed of each cylinder according to the engine rotation speed. The setting is switched or the maximum rotation speed of the rotation speed of each cylinder is set. The cylinder-specific control unit 103
The electronic governor of the distributed fuel injection pump is driven based on the operating condition from the operating condition detecting unit 101, the target rotational speed from the target rotational speed switching unit 102, and the cylinder pulse to execute the cylinder-by-cylinder control.

FIG. 2 is an enlarged sectional view of a distribution type fuel injection pump used in one embodiment of the present invention, and FIG. 3 is a perspective view of an electronic governor provided in the fuel injection pump of FIG.
4 is a conceptual explanatory view of the structure of the electronic governor, FIG. 5 is a graph showing the inductance change of the detection coil corresponding to the rotation angle of the rotor of the electronic governor, and FIG. 6 is the fuel injection timing control of the fuel injection pump of FIG. 7 is an enlarged cross-sectional view of the portion for
FIG. 3 is a system configuration diagram of a diesel engine with a supercharger using the fuel injection pump of FIG. 2.

In FIG. 2, a fuel injection pump FIP having a structure known per se is provided with a drive shaft 1 driven by an engine and a feed pump 2 driven by the drive shaft 1, and fuel is supplied to this feed pump. After being sucked from the fuel inlet 3 by the pump 2 and the supply pressure being adjusted by the regulating valve 4, it is supplied to the pump chamber 6 in the pump body 5.
The plunger 7 is slidably fitted into a plunger barrel 8 provided in the pump body 5, and a cam disk 9 connected to the drive shaft 1 via a coupling is fixed to the base of the plunger 7.

A cam surface corresponding to the number of cylinders of the engine is formed on the cam disk 9, and this cam surface is formed by a roller 11 held by a driving disk (roller holder) 10.
When the drive shaft 1 rotates, it is pressed against the cam disk 9 by the plunger spring 12.
Reciprocates while rotating on the roller 11, and the plunger 7
On the other hand, the reciprocating motion for sucking and feeding the fuel and the rotating motion for distributing the fuel are simultaneously provided.

In the suction process in which the plunger 7 moves to the left in the drawing, the fuel supplied to the pump chamber 6 is sucked from the suction port 13 through one of the suction grooves 14 formed in the axial direction of the tip of the plunger 7. Is supplied to the pump chamber 15 surrounded by the plunger barrel 8 and the plunger 7, and the suction port 13 and the suction groove 14 are separated in the pumping process in which the plunger 7 moves to the right in the drawing, the pump chamber 15 The fuel compressed inside is the vertical hole 1 of the plunger 7.
From the distribution port 17 into one of the distribution passages 18 via 6, the fuel is sent to the fuel injection nozzle 70 (see FIG. 7) via the delivery valve 19 and injected into the cylinder of the engine E. Then, every time the suction pressure feeding step is repeated, fuel is sequentially supplied into each cylinder through the adjacent distribution passage.

A cutoff port 20 communicating with the vertical hole 16 of the plunger 7 is provided in a portion of the plunger 7 exposed from the plunger barrel 8, and the cutoff port 20 is covered on the outer periphery of the plunger 7. The control sleeve 21 is slidably fitted.

The control sleeve 21 is engaged with an eccentric end 25 of a shaft 24 attached to a rotor 23 of a rotary type electronic governor 22 as shown in FIGS. 3 and 4 provided in the fuel injection pump FIP. As the rotor 23 rotates and moves in the axial direction of the plunger 7, the control sleeve 21 changes the timing at which the cut-off port 20 deviates from the right edge of the control sleeve 21 and opens in the pump chamber 6, and the injection is performed. It has the function of adjusting the end time.

The electronic governor 22 is fixed to the core 24 around which the drive coil 26 is wound, and rotatably arranged in the core 27. The electronic governor 22 is rotated clockwise in FIG. 4 by the drive current flowing through the drive coil 26. Driven rotor 23,
Return spring 28 that returns the rotor 23 to its original position
5, an iron piece 29 fixed to the shaft 24 and rotated together with the rotor 23, and a detection coil whose inductance changes in accordance with a change in the rotation angle of the iron piece 29, that is, the rotation angle θ of the rotor 23, as shown in FIG. 30 and 30. Then, the iron piece 29 and the detection coil 30 constitute a control sleeve position sensor 31.

The control sleeve 21 is adapted to be servo-controlled by the control unit 60 via the electronic governor 22 while the position thereof is constantly monitored by the control sleeve position sensor 31 having the above-mentioned structure. The increase control of the injection amount is performed by rotating the rotor 23 clockwise from the original position (servo control) by the drive current flowing through the drive coil 26, and the decrease of the fuel injection amount is controlled by the drive current. This is done by pulling the rotor 23 back to its original position by the return spring 28 upon interruption.

A fuel tank 71 is provided above the pump body 5.
An overflow valve 35 for overflowing a part of the fuel is provided (see FIG. 7). In addition,
Reference numeral 36 is a fuel temperature sensor for detecting the fuel temperature in the pump chamber 6, and 37 is a magnet valve for shutting off the fuel sucked into the pump chamber 6 when the engine is stopped.

The driving disk 10 is rotatably provided around the axis of the plunger 7.
One end of the lever 38 is connected via a pin, and the other end of the lever 38 is engaged with a timer piston 39 of the injection timing adjusting device.

In the injection timing adjusting device, as shown in FIG. 6, a timer piston 39 is slidably inserted in a cylinder 41 formed in the pump body 5, and a timer spring 39 is provided at one end of the timer piston 39. A low-pressure chamber 43 accommodating 42 is provided, and a high-pressure chamber 44 on which the fuel pressure in the pump chamber 6 acts is provided at the other end.
4 and the pressure difference between the low pressure chamber 43 and the timer spring 42
The position of the timer piston 39 is determined by the balance with the urging force of the driving disk 10, and the position of the driving disk 10 in the circumferential direction is determined.

Then, the position of the driving disc 10 in the circumferential direction is changed, whereby the roller 11 and the cam disc 9 are changed.
The contact position with the cam surface of the drive shaft changes, and the operating position of the plunger 7 with respect to the circumferential direction of the drive shaft 1 can be changed in phase to change the fuel injection timing. In the present embodiment, the injection timing is advanced (advanced) when the timer piston 39 moves downward in FIG. 6 against the biasing force of the timer spring 42 due to the pressure in the high pressure chamber 44,
The timer piston 3 is driven by the urging force of the timer spring 42.
When 9 moves upward in FIG. 6, the injection timing is delayed (retarded).

The timing control valve 45 fixed to the pump body 5 is provided with an electromagnetic plunger 47 that reciprocates by the electromagnetic force of the electromagnetic coil 46, and the needle 50 that can be seated inside the tip hole 49 of the valve holder 48 is electromagnetic. It is integrally connected to the plunger 47. When no electromagnetic force is present, the electromagnetic plunger 47 is urged toward the tip hole 49 by the spring 52 interposed between the fixed rod 51 and the fixed rod 51. It is in a blocked state. On the other hand, when an electromagnetic force is generated, the electromagnetic plunger 47 causes the spring 5
It is pulled toward the fixed rod 51 side against the urging force of 2.
As a result, the tip hole 49 and the side hole 53 formed on the side surface of the valve holder 48 communicate with each other in the valve holder 48 via the passage around the needle 50.

The high pressure chamber 44 communicates with a side hole 53 of the timing control valve 45 via a high pressure passage 54, and the low pressure chamber 43 communicates with a tip hole 49 of the timing control valve 45 via a low pressure passage 55. Therefore, by controlling the opening of the timing control valve 45, the amount of fuel pressure in the high pressure chamber 44 leaking to the low pressure chamber 43 is adjusted, and the pressure difference between the high and low pressure chambers is changed.
The position of the timer piston 39, which is determined by the balance with the timer spring 42, is changed.

The position of the timer piston 39 is detected by the timer position sensor 56. The timer position sensor 56 includes a detection coil 57 and a rod 58 connected to the timer piston 39, and the position signal is sent to the control unit 60 to determine the engine speed, the fuel temperature, the water temperature, etc. as parameters. The duty is controlled based on the difference from the signal corresponding to the selected target injection timing.

A diesel engine DE equipped with the distribution type fuel injection pump FIP having the above structure is shown in FIG.
, The main combustion chamber 6 corresponding to each cylinder is formed by the cylinder 61, the piston 62, and the cylinder head 63.
4 are formed respectively. Further, a sub combustion chamber 65 communicating with each main combustion chamber 64 is provided, and fuel is injected from each fuel injection nozzle 70 into each sub combustion chamber 65. Further, a glow plug 66 as a starting assist device is attached to each sub-combustion chamber 65.

The intake passage 67 of the engine DE is provided with a compressor 69 of a turbocharger 68 which constitutes a supercharger, and the exhaust passage 72 is provided with a turbine 73 of the turbocharger 68.

In the engine DE, a recirculation passage 74 for recirculating a part of the exhaust gas in the exhaust passage 72 to the intake passage 67.
Is provided. Then, in the middle of the return passage 74,
An EGR valve 75 for adjusting the amount of exhaust gas recirculation is provided.

The control unit 60 controls the electronic governor 22 and the timing control valve 45 based on the outputs of the engine speed sensor 76, the accelerator opening sensor 77, the water temperature sensor 78, the fuel temperature sensor 36, the timer position sensor 56 and the like. Cylinder control of the engine DE is performed.

In the above-mentioned structure, the control unit 60 is used in an operating region where the engine speed is relatively low, such as a normal idle speed range (around 700 rpm) where cylinder-by-cylinder control is performed, where rotation stability is particularly important. Is to control the fuel injection amount for each cylinder so that the rotor 23 is rotated clockwise from the original position by the drive current flowing through the drive coil 26 of the electronic governor 22, that is, the servo of the electronic governor 22. The target rotation speed is set to the maximum rotation speed or higher of the rotation speeds of the four cylinders so that the mechanism performs the increase control. Further, the control unit 60 causes the return spring 28 to rotate the rotor 23 in the operating region where the engine speed is relatively high (for example, 1200 to 1500 rpm) in which the control speed is important in the operating region where the cylinder-by-cylinder control is performed. Figure 4
The target rotation speed is set to the minimum rotation speed or lower than the rotation speed of the four cylinders so that the target rotation speed is controlled so as to rotate counterclockwise, that is, to control the reduction of the fuel injection amount.

Then, the target engine speed is set to a maximum engine speed of the four cylinders or a higher engine speed, or a relatively low engine speed operating range, and the target engine speed of the four cylinders is set to the engine speed. In the transitional region between the lowest engine speed and a relatively high engine speed operating range that is set to the lowest engine speed or less, the control amount is emphasized, and the average value of the highest engine speed and the lowest engine speed is set. The target speed is set.

FIG. 8 is a flow chart showing a target rotational speed setting routine by the control unit 60. First, it is judged whether or not the operating condition is such that the cylinder-by-cylinder control can be carried out (S
1) If the operating condition allows the cylinder-by-cylinder control to be performed (S1:
YES), it is determined whether the engine speed is higher than a predetermined speed (S2). Then, if the engine speed is equal to or lower than the predetermined speed, for example, in the normal idle speed range (S
2: NO), the target rotation speed is set to the minimum rotation speed of the rotation speeds of the four cylinders or lower (S3). on the other hand,
If the engine speed is higher than the normal idle speed range (S2: YES), the target speed is set to the minimum speed of the four cylinder speeds or lower (S4).

As described above, in the present embodiment, in the engine operating range in which the cylinder-by-cylinder control is performed, the operating range in which the engine speed is relatively low, where rotation stability is more important than control speed, such as normal idle. In the rotation speed range, the target rotation speed is set to the maximum rotation speed or higher of the four rotation speeds of the four cylinders, so that the servo mechanism of the electronic governor 22 operates to perform cylinder-based control (increase of fuel injection amount). Since the control) is performed, it is possible to improve the rotation stability and prevent hunting.

Further, in the engine operating range in which the cylinder-by-cylinder control is performed, an operating range in which the engine speed is relatively high, where control speed is more important than rotational stability, for example, engine speed is higher than the normal idle speed range. In the region, since the target rotation speed is set to the minimum rotation speed or lower of the rotation speeds of the four cylinders, the control by the cylinder (fuel injection amount is performed by the elastic force of the return spring 28 of the electronic governor 22). Therefore, quick control is possible.

In this case, the fail safe function can be provided by configuring the electronic governor 22 so that the fuel injection amount is reduced by the elastic force of the return spring 28.

[Brief description of drawings]

FIG. 1 is a block diagram showing a functional configuration of a control unit in a fuel injection control device for a diesel engine according to the present invention.

FIG. 2 is an enlarged sectional view of a distribution type fuel injection pump used in an embodiment of the present invention.

FIG. 3 is a perspective view of an electronic governor included in the distributed fuel injection pump of FIG.

FIG. 4 is a conceptual explanatory diagram of a structure of an electronic governor.

FIG. 5 is a graph showing a change in inductance of a detection coil corresponding to a rotation angle of a rotor of an electronic governor.

6 is an enlarged cross-sectional view of a portion for controlling fuel injection timing of the distributed fuel injection pump of FIG.

FIG. 7 is a system configuration diagram of a diesel engine with a supercharger using the distributed fuel injection pump of FIG.

FIG. 8 is a flowchart showing a target rotation speed setting routine by the control unit in FIG.

[Explanation of symbols]

 21 Control Sleeve 22 Electronic Governor 23 Electronic Governor Rotor 28 Electronic Governor Return Spring 45 Timing Control Valve 60 Control Unit 70 Fuel Injection Nozzle 76 Engine Speed Sensor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsumi Antomi 3-1, Shinchi Fuchu-cho, Aki-gun, Hiroshima Prefecture Mazda Co., Ltd. (72) Inventor Yusuke Kiyo 3-3 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Incorporated (72) Inventor Tomoaki Saito 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Ltd.

Claims (5)

[Claims] 1. An electronic governor for performing one of an increase and a decrease of a fuel injection amount from a fuel injection nozzle provided in each cylinder of a plurality of cylinders by a servo mechanism and the other by an elastic force of a spring. By controlling the fuel injection pump and the electronic governor in a predetermined engine operating region, the fuel injection amount from the fuel injection nozzle of each cylinder is calculated for each cylinder based on the rotation deviation between the rotation speed of the cylinder and the target rotation speed. In a fuel injection control device for a diesel engine having a cylinder-by-cylinder control unit for correction, in the engine operating range in which the cylinder-by-cylinder control unit performs the cylinder-by-cylinder control, the electronic governor Fuel injection control of a diesel engine, characterized in that the above target speed is set so that the servo mechanism of Location. 2. The electronic governor is configured so as to increase the fuel injection amount by a servo mechanism and decrease the fuel injection amount by the elastic force of the spring, and the operating region where the engine speed is relatively low. 2. The fuel injection control device for a diesel engine according to claim 1, wherein the target rotation speed is set to a maximum rotation speed or higher of the rotation speeds of the respective cylinders. 3. In the engine operating region in which the cylinder-by-cylinder control is performed by the cylinder-by-cylinder control means, in the operating region in which the engine rotational speed is relatively high, the target rotational speed is the minimum rotational speed among the rotational speeds of the respective cylinders. The fuel injection control device for a diesel engine according to claim 2, wherein the fuel injection control device is set to a value equal to or less than that. 4. An electronic governor for performing one of an increase and a decrease of a fuel injection amount from a fuel injection nozzle provided in each of a plurality of cylinders by a servo mechanism, and the other by an elastic force of a spring. By controlling the fuel injection pump and the electronic governor in a predetermined engine operating region, the fuel injection amount from the fuel injection nozzle of each cylinder is calculated for each cylinder based on the rotation deviation between the rotation speed of the cylinder and the target rotation speed. In a fuel injection control device for a diesel engine having a cylinder-by-cylinder control unit for correction, in the engine operating range in which the cylinder-by-cylinder control unit performs the cylinder-by-cylinder control, the spring The fuel injection control device for a diesel engine, wherein the target rotational speed is set so that an elastic force acts. 5. The electronic governor is configured to increase the fuel injection amount by a servo mechanism and decrease the fuel injection amount by the elastic force of the spring, and in an operating region where the engine speed is relatively high. 5. The fuel injection control device for a diesel engine according to claim 4, wherein the target rotation speed is set to a minimum rotation speed or lower than the rotation speed of each cylinder.