JP4110814B2 - Fuel injection control device for diesel engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel injection control device for a diesel engine.
[0002]
[Prior art]
In general, in an engine, intake of air from an intake passage to a combustion chamber is controlled by opening and closing an intake valve, and exhaust of exhaust gas from the combustion chamber to an exhaust passage is controlled by opening and closing an exhaust valve. The intake valve and the exhaust valve are each opened and closed at a predetermined timing by a cam attached to the cam shaft. Here, the camshaft is rotationally driven by the crankshaft via a timing belt or the like.
[0003]
As described above, the cam shaft is rotationally driven via the timing belt or the like, so that the angular velocity fluctuates. Therefore, in order to suppress such fluctuations in angular velocity, a torsional damper is often provided on the camshaft (see, for example, JP-A-11-324698). Such a torsional damper is usually formed of a rubber material.
[0004]
[Problems to be solved by the invention]
Thus, since the torsional damper is made of a rubber material, its hardness changes with temperature. Here, since the torsional damper generates heat and increases in temperature when the engine is operated, the hardness of the torsional damper varies depending on the engine operating state and the outside air temperature. The change in the hardness of the torsional damper affects the tension of the timing belt between the crankshaft and the camshaft. Therefore, in order to ensure the life of the timing belt, the maximum fuel injection amount must be suppressed while the torsional damper is hard. However, if the maximum fuel injection amount is suppressed, there arises a problem that the running performance of a vehicle equipped with the engine is deteriorated.
[0005]
The present invention has been made to solve the above-described conventional problems, and can ensure the life of the timing belt between the crankshaft and the camshaft of the engine, as well as the vehicle equipped with the engine. It is an object to be solved to provide means capable of maintaining good running performance.
[0006]
[Means for Solving the Problems]
A diesel engine fuel injection control apparatus according to a first aspect of the present invention, which has been made to solve the above problems, includes: (i) a fuel injection control apparatus for a diesel engine provided with a torsion damper that attenuates angular velocity fluctuations of a camshaft. (Ii) maximum injection amount setting means for setting the maximum injection amount of fuel, (iii) damper temperature detection means for detecting the temperature of the torsion damper, and (iv) torsion damper detected by the damper temperature detection means. When the temperature is lower than the predetermined temperature, the maximum injection amount suppression means for suppressing the maximum injection amount of fuel compared to when it is high , and ( v ) air temperature detection for detecting the intake air temperature at the time of starting the engine or a temperature corresponding thereto Means, ( vi ) engine speed detecting means for detecting engine speed, ( vii ) load detecting means for detecting engine load, and ( viii ) engine acceleration / deceleration Or a cumulative time calculation means for calculating a cumulative time of a period during which the tooth load of the timing belt for driving the camshaft is equal to or greater than a preset value , and ( ix ) a damper The temperature detecting means is configured to detect the temperature of the torsion damper based on the temperature detected by the air temperature detecting means and the accumulated time calculated by the accumulated time calculating means. is there.
[0007]
In short, the fuel injection control device of this diesel engine shortens the maximum fuel injection amount suppression time by grasping the temperature rise characteristic of the damper in order to ensure the belt life and minimize the deterioration of running performance. . According to the fuel injection control device of the diesel engine , the belt life can be effectively ensured, the running performance can be maintained well, or the deterioration of the running performance can be minimized, and the running Ru can be more effectively prevent a decrease in sex.
[0009]
A diesel engine fuel injection control apparatus according to a second aspect of the present invention includes: (i) a diesel engine fuel injection control apparatus including a torsion damper that attenuates angular velocity fluctuations of a camshaft; and (ii) maximum fuel injection. A maximum injection amount setting means for setting the amount; (iii) an air temperature detecting means for detecting an intake air temperature at the time of starting the engine or a temperature corresponding thereto; and (iv) a temperature detected by the air temperature detecting means is a predetermined temperature. When it is lower, the maximum injection amount suppression means for suppressing the maximum fuel injection amount than when it is high, (v) a rotation speed detection means for detecting the engine speed, and (vi) detecting the engine load a load detecting means, (vii) an engine acceleration and deceleration of the cumulative time period of performing, or cumulative period tooth load of the timing belt for driving a cam shaft reaches a preset value or more And (viii) suppression release means for canceling the suppression of the maximum fuel injection amount based on the cumulative time calculated by the cumulative time calculation means. It is what.
[0010]
This diesel engine fuel injection control device also ascertains the temperature rise characteristics of the damper and shortens the maximum fuel injection amount suppression time in order to ensure the belt life and minimize the deterioration in running performance. According to the fuel injection control device of the diesel engine, the belt life can be ensured, the running performance can be maintained well, or the running performance can be minimized.
[0011]
In the fuel injection control device for a diesel engine according to the first or second aspect of the present invention, the elapsed time detecting means for detecting the elapsed time after engine start is provided, and the suppression release means is detected by the elapsed time detecting means. When the elapsed time exceeds a predetermined time, it is preferable to forcibly release the suppression of the maximum fuel injection amount. In this way, it is possible to improve the run ascending.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be specifically described.
As shown in FIG. 1, in the engine 1, fuel combustion air is taken into the combustion chamber 4 from the intake passage 3 in the intake stroke in which the intake valve 2 is opened. The air in the combustion chamber 4 is compressed by the piston 5 and becomes a high temperature / high pressure state. Then, near the top dead center of the compression stroke, fuel (light oil or the like) is injected from the fuel injection valve 6 into the high-temperature and high-pressure air in the combustion chamber 4, and this fuel self-ignites and burns. The combustion gas generated by the combustion of the fuel, that is, the exhaust gas, is discharged to the exhaust passage 8 in the exhaust stroke in which the exhaust valve 7 is opened. Such a process is repeated, and the piston 5 reciprocates. The reciprocating motion of the piston 5 is converted into the rotational motion of the crankshaft 10 by the connecting rod 9 or the like.
[0013]
In the intake passage 3, as viewed from the air flow direction, in order from the upstream side, an air cleaner 11 that removes dust and the like in the air, an air flow sensor 12 that detects the air flow rate, a pump 13a of the turbocharger 13, An intercooler 14 that cools air whose temperature has increased due to supercharging, an intake air temperature sensor 19 that detects air temperature (intake air temperature), and an intake throttle valve 15 are provided. The intake passage 3 branches into a first branch intake passage 3a and a second branch intake passage 3b near the downstream end. A swirl control valve 16 is interposed in the first branch intake passage 3a.
[0014]
On the other hand, in the exhaust passage 8, the turbine 13 b of the turbocharger 13 and the first catalytic converter 17 for purifying HC, CO, NOx, etc. in the exhaust gas in order from the upstream side in the exhaust gas flow direction. And the 2nd catalytic converter 18 is interposed.
[0015]
Further, an EGR passage 21 is provided for recirculating a part of the exhaust gas in the exhaust passage 8 to the intake passage 3 as EGR gas. The EGR passage 21 includes an EGR cooler 22 for cooling the EGR gas, and an EGR gas flow rate. And an EGR control valve 23 for controlling the operation. Thereby, a part of the exhaust gas in the exhaust passage 8 can be recirculated to the intake passage 3 while the flow rate is adjusted by the EGR control valve 23.
[0016]
Fuel is supplied to the fuel injection valve 6 from the fuel tank 26 through the fuel passage 27. In the fuel passage 27, a fuel heater 28, a high-pressure fuel pump 29 driven by the crankshaft 10, and a fuel distributor (common rail) 30 for storing high-pressure fuel are interposed. The high-pressure fuel pump 29 operates so that the fuel pressure in the fuel distributor 30 detected by the pressure sensor 31 is maintained at a predetermined value or more.
[0017]
Further, the engine 1 is provided with a vacuum pump 32, a crank angle sensor 33 (engine speed sensor), a water temperature sensor 34, and an accelerator sensor (not shown).
The engine 1 is provided with a control unit C composed of a computer. The control unit C performs various controls or calculations such as fuel injection control and EGR control based on various control information.
[0018]
By the way, in the engine 1, the intake of air from the intake passage 3 to the combustion chamber 4 is controlled by opening and closing the intake valve 2, and the exhaust gas is discharged from the combustion chamber 4 to the exhaust passage 8 by opening and closing the exhaust valve 7. Be controlled. The intake valve 2 and the exhaust valve 7 are each opened and closed at a predetermined timing by a cam (not shown) attached to the cam shaft 40 (see FIG. 2). Here, the camshaft 40 is rotationally driven by the crankshaft 10 via a timing belt 42 (see FIG. 2). An auxiliary machine (not shown) such as a water pump is also rotationally driven by the crankshaft 10 via a timing belt 42 (see FIG. 2).
[0019]
Hereinafter, the cam shaft 40 or the auxiliary machine driving mechanism (hereinafter, referred to as "dynamic mechanism drive camshafts etc.".) Will be described.
As shown in FIG. 2, the camshaft drive mechanism includes a crank pulley 41 attached to the crankshaft 10 and a water pump pulley 43 for driving a water pump (not shown). And a cam pulley 44 for driving the cam shaft 40 and a pump pulley 45 for driving the high-pressure fuel pump 29. A timing belt 42 is wound around these pulleys 41, 43, 44, 45. Yes.
[0020]
Thus, the water pump, the camshaft 40, and the high-pressure fuel pump 29 are rotationally driven by the crankshaft 10 via the timing belt. The cam pulley 44 having a large torque fluctuation is provided with a torsion damper 52 that attenuates the angular speed fluctuation. Furthermore, the drive mechanism such as the camshaft is provided with an auto tensioner 47 on the slack side span of the timing belt 42.
[0021]
The timing belt 42 is laid out by changing its angle toward the inner periphery of the belt by an idler pulley 46 and a tensioner pulley 48 of an auto tensioner 47. When the crankshaft 10 rotates in the clockwise direction in the positional relationship in FIG. 2, the crank pulley 41, the water pump pulley 43, the cam pulley 44, and the pump pulley 45 rotate in the clockwise direction. At the same time, the idler pulley 46 and the tensioner pulley 48 rotate counterclockwise.
[0022]
That is, the cam pulley 44 is arranged so that the timing belt 42 enters in a slack side span (left side in FIG. 2) where the tension is relatively small, and the water pump pulley 45 and the tensioner pulley 48 are arranged in the slack side span. Has been. Thus, by driving the water pump by the timing belt 42 for driving the camshaft 40 and the high-pressure fuel pump 29, the water pump drive mechanism can be easily configured.
[0023]
Further, the pump pulley 45 is arranged so that the timing belt 42 advances in a tension side span (right side in FIG. 2), and an idler pulley 46 is arranged between the pump pulley 45 and the crank pulley 41. The idler pulley 46 presses the tension side span of the timing belt 42 from the belt outer peripheral side. As a result, the timing belt 42 is changed in direction toward the belt inner peripheral side so that the winding range around the pump pulley 45 is sufficiently large.
[0024]
As shown in FIG. 3, in the cam pulley 44, the pitch circle has a diameter twice that of the crank pulley 41. A cylindrical boss portion 55 that protrudes in the direction in which the axis L of the rotation shaft extends is provided on the inner peripheral portion of the cam pulley 44. On the other hand, a tooth portion that meshes with a tooth portion of the timing belt 42 is formed on the entire outer periphery of the cam pulley 44. Further, on the outer peripheral side of the cam pulley 44, flanges 56 are provided at both ends in the axis L direction. The flange 56 prevents the timing belt 42 from shifting in the belt width direction.
[0025]
Further, an annular torsional damper 52 is press-fitted into the boss portion 55 from the front end side in an externally fitted state. Here, the cam pulley 44 and the torsion damper 52 rotate integrally. The torsion damper 52 is disposed on the inner peripheral side of the cam pulley 44 so as to overlap the timing belt 42 in the direction of the axis L. For this reason, the torsion damper 52 does not protrude so much from the cam pulley 44. Thereby, the increase in the dimension of the engine 1 in the direction of the axis L due to the provision of the torsional damper 52 can be suppressed.
[0026]
The torsion damper 52 is obtained by integrally vulcanizing and bonding an outer peripheral mass member 57, an inner peripheral sleeve 58, and a vibration control rubber 59 positioned therebetween. A predetermined damping characteristic is obtained according to the weight of the mass member 57 and the vibration absorption characteristic of the damping rubber 59. In this embodiment, the weight of the torsion damper 52 is made substantially the same as the weight of the cam pulley 44. However, if the weight of the torsion damper 52 is 1/2 or more of the weight of the cam pulley 44, a sufficient damping action can be obtained.
[0027]
The cam pulley 44 has two through holes 61 penetrating in the axis L direction. They are formed at positions symmetrical to each other in the diametrical direction. On the other hand, a through hole 58 is also formed in the torsion damper 52 at a position corresponding to the through hole 61 of the cam pulley 44. Accordingly, when the operator attaches the cam pulley 44 to the cam shaft 40, the alignment mark on the cylinder head side can be confirmed through the through holes 60 and 61.
[0028]
In the torsional damper 52, the hardness of the vibration damping rubber 59 formed of a rubber material changes according to the temperature. That is, since the vibration damping rubber 59 or the torsional damper 52 generates heat and increases in temperature when the engine is operated, the hardness of the vibration damping rubber 59 varies considerably depending on the engine operating condition and the outside air temperature. . The change in the hardness of the damping rubber 59 affects the tension of the timing belt 42. Therefore, in this engine 1, in order to ensure the life of the timing belt 42, the maximum fuel injection amount must be suppressed while the damping rubber 59 is hard (for example, at 15 ° C. or less). However, it should be avoided as much as possible that the running performance of the vehicle equipped with the engine 1 deteriorates.
[0029]
Therefore, in the engine 1, by causing the control unit C to perform the fuel injection control as described below, the life of the timing belt 42 is sufficiently ensured and the running performance of the vehicle on which the engine 1 is mounted is improved. It maintains or suppresses the fall of runnability as much as possible.
[0030]
First, the outline of the fuel injection control by the control unit C will be described.
That is, when this fuel injection control is performed, the intake air temperature detected by the intake air temperature sensor 19, the engine speed detected by the crank angle sensor 33 (engine speed sensor), and the load detection means (accelerator sensor) are detected. Various control information such as the engine load (accelerator opening) and the engine water temperature detected by the water temperature sensor 34 is input to the control unit C.
[0031]
The control unit C sets the maximum fuel injection amount of the fuel injection valve 6 in order to prevent an excessive tension from being applied to the timing belt 42 when the torsion damper 52 is hard (when the temperature is low). Further, the control unit C calculates the accumulated time when the engine speed and the engine load are operated in a preset operation region. Then, the control unit C detects the temperature of the torsion damper 52 based on the intake air temperature at the time of starting the engine and the accumulated time. Further, the control unit C suppresses the maximum fuel injection amount of the fuel injection valve 6 when the temperature of the torsional damper 52 is lower than a predetermined temperature (for example, 15 ° C.) compared to when the temperature is higher than this.
[0032]
Further, the control unit C releases the above-described suppression of the maximum fuel injection amount based on the accumulated time. The control unit C forcibly cancels the suppression of the maximum fuel injection amount when the elapsed time after engine startup exceeds a predetermined time. In short, in this fuel injection control, in order to ensure the life of the timing belt 42 and to minimize the deterioration of the running performance of the vehicle equipped with the engine 1, the temperature rise characteristic of the torsion damper 52 is grasped to obtain the maximum fuel. Reduce the injection suppression time. Thus, by performing this fuel injection control, it is possible to ensure the belt life and minimize the deterioration in running performance.
[0033]
Hereinafter, a specific control method of this fuel injection control will be described.
FIG. 8 shows an example of change characteristics with respect to time of the engine water temperature, the engine speed, and the temperature of the torsional damper 52 during the high-speed acceleration / deceleration operation. As is apparent from FIG. 8, the temperature of the torsional damper 52 rises greatly during acceleration / deceleration at around 3000 rpm, but hardly rises (and does not drop significantly) in other steady rotations. Therefore, it is possible to accumulate the operation time of the torsional damper 52 in the temperature rise region and cancel the maximum injection amount suppression after a predetermined period.
[0034]
FIG. 4 is a graph showing the time required for the temperature of the torsional damper 52 to reach 15 ° C., that is, the accumulated time, using the engine load and the intake air temperature at the start of the engine as parameters. If the temperature of the torsional damper 52 is 15 ° C. or higher, the hardness of the vibration damping rubber 59 is sufficiently lowered, so that the timing belt 42 is not excessively tensioned. Therefore, when the temperature of the torsional damper 52 becomes 15 ° C. or higher, the suppression of the maximum injection amount is released. In FIG. 4, the engine output is set to 74 kw below −5 ° C., and the engine output is set to 88 kw above −15 ° C.
[0035]
In the example shown in FIG. 4, the engine speed is set to 3000 to 3500 rpm, because the temperature rise gradient of the torsion damper 52 is large in this range.
FIG. 5 shows a change characteristic of the temperature rise characteristic of the torsion damper 52 with respect to the engine speed. As is clear from FIG. 5, the temperature increase gradient is very large when the engine speed is in the range of 3000 to 3500 rpm. In the example shown in FIG. 5, the temperature of the torsion damper 52 is measured while increasing the engine speed from normal temperature to full load (F / L).
[0036]
FIG. 6 shows the results of measuring the temperature rise gradient of the torsional damper 52 from room temperature to a constant load of 3200 rpm. As can be seen from FIG. 6, the gradient immediately after the start of the engine is large and then gentle, but the gradient for calculating the release time of suppression of the maximum injection amount is a linear portion in the latter half from the viewpoint of the safety side. Is preferably adopted.
[0037]
In this case, the change characteristics with respect to the outside air temperature (the intake air temperature at the time of starting the engine) and the load until the temperature of the torsion damper 52 reaches 15 ° C. at which the maximum injection amount does not need to be suppressed are as shown in FIG. is there. The control constant of this fuel injection control needs to be set based on this data, but both are shorter than the required time (-5 ° C. or lower: 11 minutes, −5 to 15 ° C .: 4 minutes), and this region is frequently used. The greater the amount, the faster the suppression of the maximum injection amount can be released.
[0038]
As shown in FIG. 7, the tooth load of the timing belt 42 in extreme cold has a high value at 3000 to 3500 rpm, and it is considered that the temperature of the torsion damper 52 rises in this range. Moreover, if the operation time in the full load region is counted, the time until the maximum injection amount suppression is canceled is long (for example, when the outside air temperature is −30 ° C., the accumulated time is 9.4 minutes), and thus it is practical. Considering the frequency, the engine load should be 25% or more. Therefore, in this fuel injection control, it is preferable that the engine load at an engine speed of 3000 to 3500 rpm is 25% or more in the cumulative operation time region.
[0039]
As described above, according to this fuel injection control, the life of the timing belt 42 between the crankshaft 10 and the camshaft 40 of the engine 1 can be secured, and the traveling performance of the vehicle on which the engine 1 is mounted is improved. It can be maintained, or a decrease in running performance can be suppressed as much as possible.
[Brief description of the drawings]
FIG. 1 is a system configuration diagram of a diesel engine in which fuel injection control is performed according to the present invention.
FIG. 2 is a front view of the diesel engine shown in FIG.
FIG. 3 is a side sectional view of a cam pulley of the diesel engine shown in FIG.
FIG. 4 is a graph showing cumulative time as parameters of intake air temperature at engine start and engine load.
FIG. 5 is a graph showing a change characteristic of a temperature increase characteristic of a torsion damper with respect to an engine speed.
FIG. 6 is a graph showing a result of measuring a temperature rise gradient of a torsion damper from a normal temperature to a constant load of 3200 rpm.
FIG. 7 is a graph showing a change characteristic of a tooth load with respect to an engine speed.
FIG. 8 is a graph showing an example of change characteristics with respect to time of engine water temperature, engine speed, and torsional damper temperature during high-speed acceleration / deceleration operation;
[Explanation of symbols]
C ... Control unit, 1 ... Engine, 2 ... Intake valve, 3 ... Intake passage, 4 ... Combustion chamber, 5 ... Piston, 6 ... Fuel injection valve, 7 ... Exhaust valve, 8 ... Exhaust passage, 9 ... Connecting rod, 10 DESCRIPTION OF SYMBOLS ... Crankshaft, 11 ... Air cleaner, 12 ... Air flow sensor, 13 ... Turbocharger, 14 ... Intercooler, 15 ... Intake throttle valve, 16 ... Swirl control valve, 17 ... First catalytic converter, 18 ... Second catalytic converter, DESCRIPTION OF SYMBOLS 19 ... Intake temperature sensor, 33 ... Crank angle sensor, 34 ... Water temperature sensor, 40 ... Cam shaft, 441 ... Cam pulley, 42 ... Timing belt, 44 ... Cam pulley, 52 ... Torsion damper, 59 ... Damping rubber

Claims (3)

In a fuel injection control device for a diesel engine having a torsional damper that attenuates angular velocity fluctuations of a camshaft,
Maximum injection amount setting means for setting the maximum injection amount of fuel;
Damper temperature detecting means for detecting the temperature of the torsion damper;
Maximum injection amount suppression means for suppressing the maximum fuel injection amount compared to when the temperature of the torsional damper detected by the damper temperature detection means is lower than a predetermined temperature ; and
An air temperature detecting means for detecting an intake air temperature at the time of starting the engine or a temperature corresponding thereto;
A rotational speed detection means for detecting the rotational speed of the engine;
Load detection means for detecting engine load;
A cumulative time calculating means for calculating a cumulative time of a period during which the engine is accelerated or decelerated, or a cumulative time of a period when the tooth load of the timing belt for driving the camshaft is equal to or greater than a preset value ;
The damper temperature detecting means detects the temperature of the torsion damper based on the temperature detected by the air temperature detecting means and the accumulated time calculated by the accumulated time calculating means. Diesel engine fuel injection control device. In a fuel injection control device for a diesel engine having a torsional damper that attenuates angular velocity fluctuations of a camshaft,
Maximum injection amount setting means for setting the maximum injection amount of fuel;
An air temperature detecting means for detecting an intake air temperature at the time of starting the engine or a temperature corresponding thereto;
When the temperature detected by the air temperature detection means is lower than a predetermined temperature, the maximum injection amount suppression means for suppressing the maximum injection amount of fuel compared to when it is high,
A rotational speed detection means for detecting the rotational speed of the engine;
Load detection means for detecting engine load;
Accumulated time period of performing the acceleration and deceleration of the engine, or the cumulative time calculating means for calculating a cumulative time period tooth load of the timing belt for driving a cam shaft reaches a preset value or more,
A fuel injection control device for a diesel engine, comprising: a suppression release unit that cancels the suppression of the maximum fuel injection amount based on the cumulative time calculated by the cumulative time calculation unit. Elapsed time detection means for detecting the elapsed time after startup is provided,
The suppression release means forcibly releases the suppression of the maximum fuel injection amount when the elapsed time detected by the elapsed time detection means exceeds a predetermined time. 3. A fuel injection control device for a diesel engine according to 1 or 2 .

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