JP4193547B2 - Injection timing control device for fuel injection pump - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an injection timing control device for a fuel injection pump provided in a diesel engine, and more particularly to an injection timing control device for a fuel injection pump that controls a fuel injection timing using a hydraulic electronic timer.
[0002]
[Prior art]
As one form of a fuel injection pump provided in a diesel engine, one using a hydraulic electronic timer (hereinafter referred to as a hydraulic timer) for controlling the fuel injection timing is known. Since the structure of the hydraulic timer is well known (see, for example, Patent Document 1 and Patent Document 2), a detailed description is omitted here, but a general hydraulic timer includes a piston slidable in a timer cylinder, Oil (pressure oil) is supplied from an oil pump into a piston chamber defined by the piston. The piston is biased toward the piston chamber by a spring and moves according to the amount of oil supplied from the oil pump. The movement of the piston is converted into the rotational motion of the rotating body via the eccentric cam, and the fuel injection timing is advanced according to the rotational angle of the rotating body.
[0003]
The fuel injection pump is provided with a timing control valve (TCV) for controlling the amount of oil supplied from the oil pump into the piston chamber and the amount of oil extracted from the piston chamber in order to control the movement amount of the piston of the hydraulic timer. . By operating the TCV and supplying oil to the piston chamber, the piston chamber is pushed wide, the piston moves forward, and the fuel injection timing is advanced. Conversely, by removing oil from the piston chamber, the piston moves backward by the biasing force of the spring, and the fuel injection timing is retarded. The TCV is feedback controlled based on the difference between the target fuel injection timing and the actual fuel injection timing.
[0004]
By the way, when starting the engine, particularly when starting from the cold state, it is desirable to advance the fuel injection timing in order to improve the startability of the engine. Since the piston of the hydraulic timer is urged toward the piston chamber by a spring, when the oil pressure when the engine is stopped is lowered, the oil is released from the piston chamber and the piston is positioned at the most retarded position. Therefore, it is desirable to supply oil to the hydraulic timer immediately after the engine starter is operated and move the piston of the hydraulic timer to the advance side.
[0005]
In order to move the piston to the advance side, the target fuel injection timing may be set to the advance side and the TCV may be feedback controlled. However, when the engine speed is low, the interval between pulses output in synchronization with the cranking of the engine is longer than the calculation time of the CPU, so that the CPU calculation overflows and calculation for feedback control is performed. Can not do. For this reason, the TCV cannot be controlled until the engine speed increases, and the TCV remains closed.
[0006]
In response to such a problem at the time of starting the engine, Patent Document 2 proposes the following technique.
In the technique described in Patent Document 2, a high pressure chamber (piston chamber) to which pressure oil is supplied from an oil pump is formed on one side of a timer piston, and a low pressure opened to atmospheric pressure on one side of the timer piston. A chamber is formed, and a piston is biased toward the high pressure chamber by a spring disposed in the low pressure chamber. The piston forms a flow path that connects the high-pressure chamber and the low-pressure chamber, and is provided with a spool-type servo valve. By operating the spool with a push rod that moves in one axis by motor drive, To control. In addition, the piston is provided with a stopper that regulates the operating range of the spool, and even if the piston moves to the high pressure chamber side due to the biasing force of the spring when the engine is stopped and the push rod and spool are separated, the servo valve is closed by the stopper. I can do it.
[0007]
In the technique described in Patent Document 2, when the engine is started, first, the push rod is moved to the position where the protrusion amount is minimum by open loop control, and the piston is moved to the most advanced position. When the engine rotation speed reaches a predetermined rotation speed, switching to feedback control is performed to move the push rod, thereby achieving proper injection timing control at the time of engine start.
[0008]
[Patent Document 1]
Japanese Patent Laid-Open No. 10-82339 [Patent Document 2]
Japanese Patent Laid-Open No. 9-264161
[Problems to be solved by the invention]
However, since the oil pump is operated by the rotation of the crankshaft, it takes time for the oil pressure to rise after the operation of the engine starter to operate. Especially at low temperatures, cranking rotation is low, so the time until the hydraulic pressure rises is long. That is, as in the technique described in Patent Document 2, even if an attempt is made to advance the piston to the most advanced position by open loop control after the engine is started, the oil pressure in the oil passage is low immediately after the engine is started. It takes time to move to the most advanced position, and it is difficult to start the engine quickly.
[0010]
The technique described in Patent Document 2 prevents a decrease in hydraulic pressure in the high-pressure chamber when the engine is stopped by providing a piston with a stopper that regulates the operating range of the spool. However, even if such measures are taken, there is still a possibility that the hydraulic pressure in the piston chamber will be lost when the engine is not operated for a long time. The technique described in Patent Document 2 is based on a hydraulic timer provided with a spool type servo valve, and it is further necessary to provide a stopper on the piston for regulating the operating range of the spool. That is, the technique described in Patent Document 2 is not a technique that can be widely applied to all general hydraulic timers.
[0011]
The present invention was devised in view of such problems, and it is possible to quickly start the engine and to control the injection timing widely applicable to a fuel injection pump having a general hydraulic timer. The purpose is to provide.
[0012]
[Means for Solving the Problems]
The fuel injection pump premised on the present invention is a fuel injection pump having a general hydraulic timer, and specifically, a piston chamber to which pressure oil is supplied from an oil pump driven by an engine, and a piston chamber A piston that moves in accordance with the amount of pressure oil supplied from the oil pump and an urging means that urges the piston toward the piston chamber, and an amount of pressure oil that is supplied from the oil pump into the piston chamber And a fuel injection timing is advanced in accordance with the amount of movement of the piston.
[0013]
The present invention has sought to solve the above problems by devising the control contents of such a fuel injection pump. More specifically, when the engine is stopped, the control means for controlling the control valve supplies pressure oil into the piston chamber to move the piston to the advance side, and then closes the control valve. When the engine is started, if the engine speed does not exceed the predetermined speed and a predetermined time has not elapsed since the start of the engine starter , the control valve is kept closed and the engine speed is set to the predetermined speed. Is exceeded, the feedback control of the control valve is started so that the actual fuel injection timing approaches the target fuel injection timing regardless of the predetermined time, and the engine rotational speed does not exceed the predetermined rotational speed. and to open the control valve by the open-loop control after the above predetermined time elapses Once you.
[0014]
Thus, by closing the control valve with the piston moved to the advance side, the engine can be started with the piston on the advance side at the next start. In addition, when the engine is started, the control valve is not opened immediately, but is kept closed until a predetermined time has elapsed since the start of the engine starter, so that the hydraulic pressure of the hydraulic oil supplied by the oil pump can be reduced. It is possible to prevent the pressure oil in the piston chamber from flowing back into the hydraulic piping due to the rise delay and returning the piston to the retarded angle side. That is, according to the present invention, by performing the control at the time of engine stop and the control at the time of engine start as described above, the fuel injection timing can be set to the advance side immediately after the engine start, and the engine can be quickly operated. Can be started. In addition, the present invention is characterized by the control contents of the control valve, and since conventional fuel injection pumps and hydraulic timers can be used, they are widely used in fuel injection pumps equipped with general hydraulic timers. Can be applied.
[0015]
The predetermined time is preferably set to a time from when the engine starter is operated until the oil pressure of the pressure oil supplied to the piston chamber rises after the oil pump rotates. Specifically, it may be set to around 5 seconds depending on the size of the engine and the capacity of the oil pump.
[0016]
The predetermined rotational speed referred to here may be any calculation for the feedback control of the control valve rotation speed is started (referred canceling engine speed) or more by CPU, preferably, is set to the release speed. In this way, by switching to feedback control as soon as the engine speed exceeds the predetermined speed, appropriate injection timing control according to the operating state of the engine becomes possible at an early stage, preventing deterioration of fuel consumption and exhaust gas performance. can do.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a configuration of an engine control system to which an injection timing control device for a fuel injection pump according to the present invention is applied. As shown in the figure, this control system is controlled by a diesel engine (hereinafter simply referred to as an engine) 1 having a fuel injection pump 2 having a hydraulic timer 3. The configurations of the fuel injection pump 2 and the hydraulic timer 3 are well known, and in the present invention, these configurations are not characterized, and thus a detailed description thereof is omitted. However, the hydraulic timer 3 includes a cylinder as a part related to the present invention. 4, a piston 5 defined by the piston 5, and a spring 7 that biases the piston 5 toward the piston chamber 6.
[0018]
The piston chamber 6 of the hydraulic timer 3 is connected to an oil pump 8 driven by the engine 1 and a hydraulic pipe 10. A timing control valve (control valve: hereinafter abbreviated as TCV) 9 is provided in the middle of the hydraulic pipe 10. The TCV 9 includes an IN side valve 9a and an OUT side valve 9b. The IN side valve 9a controls the amount of oil supplied from the oil pump 8 to the piston chamber 6, and the OUT side valve 9b is returned from the piston chamber 6 to the oil pump 8. The amount of oil is controlled. The movement of the piston 5 is converted into a rotational motion of a rotating body (not shown) via an eccentric cam (not shown), and the fuel injection timing of the fuel injection pump 2 is advanced according to the rotational angle of the rotating body. However, the piston 5 moves to the advance side according to the amount of oil supplied to the piston chamber 6, and moves to the retard side according to the amount of oil withdrawn from the piston chamber 6. Therefore, the fuel injection timing of the fuel injection pump 2 can be controlled to both the advance side and the retard side by controlling the TCV 9.
[0019]
In this control system, the control unit 12 controls the TCV 9. A detection signal from a crank angle sensor 13 that detects a crank angle of the engine 1, an ON / OFF signal from a key switch 14, and a clock signal from a timer 15 are input to the control unit 12. Although the timer 15 is provided outside the control unit 12 in the figure, an internal timer of the control unit 12 can also be used.
[0020]
This control system is characterized by the contents of control of the TCV 9 by the control unit 12. The control content of the control unit 12 can be described using the flowcharts of FIGS. 2 and 3 and the graphs of FIGS. FIG. 4 also shows changes over time in the engine rotation speed, fuel injection timing, TCV power supply voltage, and TCV control state when the engine is stopped. FIGS. 5 and 6 also show changes over time in the engine rotational speed, the oil pump supply hydraulic pressure, the TCV power supply voltage, and the TCV control state when the engine is started.
[0021]
First, the control method of the TCV 9 when the engine is stopped will be described with reference to the graph of FIG. Since the engine 1 stops when the key switch 14 is turned off and the fuel injection is stopped, in the engine stop time control, first, in step S1, it is determined whether or not an OFF signal is input from the key switch 14. Until the OFF signal is input from the key switch 14, feedback control (normal control) of the TCV 9 based on the difference between the target fuel injection timing and the actual fuel injection timing is performed in step S5.
[0022]
When an OFF signal is input from the key switch 14 (time t11 in FIG. 4), the process proceeds to step S2, and after setting the target value in the feedback control map to the maximum value that the hydraulic timer 3 can advance, Control of TCV9 is continued. Alternatively, the hydraulic timer 3 may be advanced the most advanced by open loop control. In general TCV, the power supply for TCV is cut off at the same time when the key switch is turned off. However, in this embodiment, the arrangement of the power supply for TCV is changed so that the engine speed becomes a predetermined speed or less. The power can be supplied to the TCV9. The predetermined rotation speed only needs to be equal to or higher than the rotation speed (release rotation speed) of the engine 1 at which the CPU in the control unit 12 can start computation, and is preferably set to be equal to or lower than the idle rotation speed. Usually, the release rotation speed is about 160 rpm. In FIG. 4, the predetermined rotation speed is set to the release rotation speed.
[0023]
In step S3, the engine rotational speed is calculated using the crank angle signal from the crank angle sensor 13, and it is determined whether the engine rotational speed is equal to or lower than the release rotational speed. While the engine rotation speed is higher than the release rotation speed, the control of the TCV 9 is continued. Then, when the engine rotational speed becomes equal to or lower than the release rotational speed (time t12 in FIG. 4), the process proceeds to step S4 and the control of the TCV 9 is stopped. The TCV 9 is in a state where both the IN side valve 9a and the OUT side valve 9b are closed due to the stop of control.
[0024]
As a result, oil is accumulated in the piston chamber 6 of the hydraulic timer 3 to the maximum extent, and the piston 5 stops in the most advanced state. That is, the hydraulic timer 3 stops in the most advanced state. Since the TCV 9 is closed, the oil 1 does not escape from the piston chamber 6 and the engine 1 can be started from the state where the hydraulic timer 3 has advanced the most at the next engine start.
[0025]
next. A control method of the TCV 9 at the time of engine start will be described with reference to the graphs of FIGS. Since the engine 1 is started when the key switch 14 is turned on and an engine starter (not shown) is operated, in the engine start-up control, first, in step S11, it is determined whether or not an ON signal is input from the key switch 14. .
[0026]
When an ON signal is input from the key switch 14 in step S11 (time t21 in FIG. 5 and time t31 in FIG. 6), the TCV supply power is turned on and the TCV9 becomes controllable, but in step S12, the TCV9 is closed. Leave it alone. Next, it progresses to step S13 and it is determined whether the engine rotational speed exceeded predetermined rotational speed. The predetermined rotational speed here may be equal to or higher than the release rotational speed, and is preferably set to be equal to or lower than the idle rotational speed, similarly to the predetermined rotational speed in the engine stop time control. 5 and 6, the predetermined rotation speed is set to the release rotation speed.
[0027]
While the engine rotation speed is smaller than the release rotation speed, the process proceeds to step S14, the clock signal from the timer 14 is counted, and the elapsed time from the operation start point of the engine starter (time point t22 in FIG. 5, time point t32 in FIG. 6). Determines whether or not the predetermined delay time has been exceeded. There is a slight time lag before the key switch 14 is turned on and the engine starter is activated. The delay time is set to the time from when the engine starter is activated until the oil pressure supplied to the oil pressure timer 3 rises after the oil pump 8 rotates. Depending on the size of the engine 1 and the capacity of the oil pump 8, the delay time may be set to around 5 seconds. Be up engine rotational speed exceeds a canceling engine speed, and the elapsed time to greater than the delay time returns to step S12, and keeps TCV9 is closed.
[0028]
Since the rotation speed of the engine 1 increases instantaneously after the first explosion, when the first explosion occurs within the delay time, the engine rotation speed exceeds the release rotation speed before the delay time elapses as shown in FIG. There is a case. If the engine rotational speed exceeds the release rotational speed in step S13 (time t23 in FIG. 5), the process proceeds to step S16. In step S16, the control of the TCV 9 is switched from open loop control (closed control) to normal control. That is, the control unit 12 feedback-controls the TCV 9 so that the actual fuel injection timing becomes the target fuel injection timing set according to the engine water temperature.
[0029]
On the other hand, in the engine 1 that has been left unused for a long period of time, even if the TCV 9 is closed with the oil stored in the piston chamber 6 by the aforementioned engine stop control, the piston 5 is pushed by the spring 7. By continuing to be performed, there is a possibility that the oil gradually escapes from the piston chamber 6. In such a case, since the fuel injection timing is retarded in accordance with the retraction of the piston 6, the engine 1 is difficult to start, and the engine rotation speed is delayed without exceeding the release rotation speed as shown in FIG. Time may elapse. If the elapsed time exceeds the delay time in step S14 (time t33 in FIG. 6), the process proceeds to step S15. In step S15, the control of the TCV 9 is switched from the control to the closed state to the control to the open state while maintaining the open loop control. That is, the TCV 9 is opened to allow the piston chamber 6 and the oil pump 8 to communicate with each other. As a result, even if the oil in the piston chamber 6 has fallen out, the oil is supplied from the oil pump 8 to the piston chamber 6 so that the piston 5 moves forward, and the fuel injection timing by the hydraulic timer 3 is advanced. Is done.
[0030]
After the process of step S15, the process returns to step S13, and it is determined whether the engine rotation speed exceeds the release rotation speed. Until the engine rotational speed exceeds the release rotational speed, the open loop control (open control) of the TCV 9 is continued. Then, when the engine rotation speed exceeds the release rotation speed (time t34 in FIG. 6), the process proceeds to step S16. The control of the TCV 9 is switched from open loop control (open control) to normal feedback control.
[0031]
In this way, the TCV 9 is not opened immediately after the key switch 14 is turned on, but the TCV 9 is kept closed until the delay time elapses from the start of the operation of the engine starter. It is possible to prevent the pressure oil in the piston chamber 6 from flowing back into the hydraulic pipe 10 due to the delay in the rise of the hydraulic pressure and returning the piston 5 to the retard side. Also, when the engine speed exceeds the release speed, the control of the TCV 9 is immediately switched to feedback control regardless of the delay time, thereby enabling appropriate injection timing control according to the operating state of the engine 1 at an early stage. Thus, deterioration of fuel consumption and exhaust gas performance can be prevented.
[0032]
That is, according to the present control system (the engine control system to which the fuel injection pump injection timing control device of the present invention is applied), by performing the control at the time of engine stop and the control at the time of engine start as described above, The fuel injection timing can be set to the advance side immediately after the engine is started, and the engine 1 can be started quickly. This effect is particularly remarkable at low temperatures where cranking rotation is slow and hydraulic pressure rises slowly. Further, as described above, the present control system is characterized by the contents of control of the TCV 9, and the conventional fuel injection pump 2 and hydraulic timer 3 themselves can be used, so that a general hydraulic timer is provided. It can be widely applied to fuel injection pumps.
[0033]
Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, in the control at the time of starting the engine, the TCV 9 is closed until the delay time elapses, and when the delay time elapses, the TCV 9 is subjected to open loop control (open control) according to the engine speed at that time. Feedback control may be performed.
[0034]
【The invention's effect】
As described above in detail, according to the fuel injection pump injection timing control device of the present invention, the control at the time of engine stop in which the control valve is closed with the piston moved to the advance side, and the control at the time of engine start immediately. If the engine speed does not exceed the predetermined speed and the predetermined time has not elapsed since the start of the engine starter , instead of opening the valve , the control valve is kept closed. By performing this, the fuel injection timing can be set to the advance side immediately after the engine is started, and the engine can be started quickly. Moreover, according to the fuel injection pump injection timing control device of the present invention, conventional fuel injection pumps and hydraulic timers themselves can be used, and therefore can be widely applied to fuel injection pumps equipped with general hydraulic timers. be able to.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an engine control system to which an injection timing control device for a fuel injection pump according to the present invention is applied.
FIG. 2 is a flowchart showing the contents of TCV control when the engine is stopped.
FIG. 3 is a flowchart showing the contents of TCV control when the engine is started.
FIG. 4 is a graph showing changes in engine rotational speed, fuel injection timing, TCV power supply voltage, and TCV control state over time when the engine is stopped.
FIG. 5 also shows changes over time in engine rotation speed, oil pump supply hydraulic pressure, TCV power supply voltage, and TCV control state when the engine is started.
FIG. 6 also shows changes over time in engine rotation speed, oil pump supply hydraulic pressure, TCV power supply voltage, and TCV control state when the engine is started.
[Explanation of symbols]
1 Diesel Engine 2 Fuel Injection Control Device 3 Hydraulic Timer 4 Cylinder 5 Piston 6 Piston Chamber 7 Spring 8 Oil Pump 9 Timing Control Valve (TCV)
9a IN side valve 9b OUT side valve 10 Hydraulic piping 12 Control unit 13 Crank angle sensor 14 Key switch 15 Timer

Claims (3)

A piston chamber to which pressure oil is supplied from an oil pump driven by an engine; a piston that forms one side surface of the piston chamber and moves according to the amount of pressure oil supplied from the oil pump; and An urging means for urging the piston chamber side and a control valve for controlling the amount of pressure oil supplied from the oil pump into the piston chamber are provided, and the fuel injection timing is advanced according to the movement amount of the piston. In the injection timing control device of the fuel injection pump,
Comprising control means for controlling the control valve,
When the engine is stopped, the control means supplies pressure oil into the piston chamber and moves the piston to the advance side, then closes the control valve,
When the engine is started, if the engine speed does not exceed the predetermined speed and the predetermined time has not elapsed since the start of the engine starter , the control valve is kept closed and the engine speed exceeds the predetermined speed. In this case, feedback control of the control valve is started so that the actual fuel injection timing approaches the target fuel injection timing regardless of the predetermined time, and the predetermined rotation speed does not exceed the predetermined rotation speed. time and wherein the opening the control valve by the elapsed Once you open-loop control after the, the fuel injection pump injection timing control device. The predetermined rotational speed, and wherein the engine rotational speed der Rukoto which the control means can begin operation, the injection timing control device for a fuel injection pump of claim 1, wherein.   The time until the hydraulic pressure of the pressure oil supplied to the piston chamber rises after the oil starter is rotated after the engine starter is operated is set as the predetermined time. 3. An injection timing control device for a fuel injection pump according to 1 or 2.

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