JP3973418B2 - Premixed compression self-ignition engine and control method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a technique for avoiding abnormal combustion in a premixed compression self-ignition engine that does not include ignition means or fuel injection means and burns by compressing and self-igniting premixed air.
[0002]
[Prior art]
6 to 10 show a conventional premixed compression auto-ignition engine and a combustion cycle.
FIG. 6 shows an intake stroke, in which there is a mixer that stirs and mixes clean air and fuel gas separately supplied upstream of the intake pipe 4 (not shown), and the lean premixed gas Mx premixed by the mixer burns. It is supplied to the chamber 3.
FIG. 7 shows a compression stroke in which the premixed gas Mx is compressed at a high compression ratio, which is a feature of the premixed compression self-ignition engine.
FIG. 8 shows a combustion / expansion stroke, in which compression auto-ignition of the premixed gas Mx is performed in the vicinity of the top dead center of the piston, and combustion and expansion occur to generate an output. Since the ignition timing at this time is based on compression self-ignition, there is a drawback that the controllability is low as compared with the spark ignition method and the fuel injection method.
FIG. 9 shows the exhaust stroke.
[0003]
As described above, even if the combustion cycle of the premixed compression auto-ignition engine is the usual four cycles, the combustion efficiency is good in terms of thermodynamics because of combustion at a high compression ratio. Further, since the fuel-lean premixed gas Mx can be combusted, there are advantages such as low-temperature combustion and low NOx in the exhaust gas.
As described above, the premixed compression self-ignition engine has many merits (as described above), and is therefore an internal combustion engine that has attracted much attention recently.
[0004]
On the other hand, in the premixed compression self-ignition engine, the ignition timing cannot be accurately controlled due to the combustion by the compression auto-ignition, and abnormal combustion (hereinafter referred to as abnormal combustion) due to a “deviation” of the ignition timing due to some disturbance. Can not be avoided).
In addition, there is a drawback that high-load operation that is likely to cause knocking cannot be performed, and that high-power operation that is comparable to conventional spark ignition or fuel injection combustion engines is difficult.
[0005]
Here, in the premixed compression self-ignition engine, the occurrence of knocking that causes noise and engine damage is mainly caused by three factors: intake air temperature, intake air pressure, and fuel concentration.
FIG. 10 shows the occurrence of knocking under the operating conditions of the premixed compression auto-ignition engine when the intake air temperature and the intake air pressure are constant, as a relationship between the output torque and the rotational speed.
[0006]
In FIG. 10, a knock combustion limit characteristic curve (hereinafter referred to as a knock generation curve) that divides the knocking combustion region (K) and the normal combustion region (N) with the vertical axis as the torque, that is, the fuel supply amount, and the horizontal axis as the engine speed. Abbreviated.) P. As can be seen from the knock generation curve P, there is a tendency that knocking is likely to occur even at low torque at high speeds, and that knocking is unlikely to occur even at high torques at low speeds.
[0007]
As a result of various research and development, the inventors have invented means for avoiding the knocking combustion region (K) to the normal combustion region (N) by changing the operating condition on the engine side on the premise of the knocking occurrence condition of FIG.
The present invention provides a premixed compression auto-ignition engine having means for avoiding knocking and a control method thereof.
[0008]
Japanese Patent Laid-Open No. 11-241626 discloses a knocking control device for an engine. The target engine is a spark ignition system, and when knocking occurs, the fuel is directly injected into the combustion chamber by direct injection. This is a technique separate from the combustion method and the knocking avoidance method of the present invention.
[0009]
[Problems to be solved by the invention]
The present invention has been proposed in view of the above-mentioned problems of the prior art, and aims to operate at a load as high as that of a conventional combustion engine of a spark ignition system or a fuel injection system. An object of the present invention is to provide a premixed compression self-ignition engine capable of avoiding abnormal combustion even when abnormal combustion such as knocking occurs and a control method therefor.
[0010]
[Means for Solving the Problems]
According to the present invention, the fuel injection valve (11) in which the fuel injected into the intake pipe (4) is mixed with the intake air is provided, and the fuel that is agitated and mixed by the fuel injection valve (11) reaches the combustion. An output transmission system comprising a chamber (3), a knocking sensor (13) for detecting abnormal combustion, a rotation sensor (15) for detecting the engine speed, and a continuously variable transmission (19) In the premixed compression self-ignition engine in which the load (21) is connected to (16), the fuel injection valve (13) receives signals from the knocking sensor (13), the rotation sensor (15), and the load (21). 11) and a continuously variable transmission (19) are provided, and when the knocking sensor (13) detects the occurrence of knocking, the controller (30) controls the continuously variable transmission (19). Control the load) Decrease engine speed, turn engine speed, then determine if knocking is avoided. If knocking is not suppressed, reduce engine speed. If knocking is suppressed, load is required. It is determined whether or not the output of the engine is insufficient, and if it is insufficient, the fuel injection valve (11) is controlled to increase the fuel supply.
[0011]
Here, the load (21) is preferably a load that converges to a constant rotational speed even when the transmission ratio of the continuously variable transmission (19) is changed. For example, a generator, GHP (gas heat pump) The compressor for compressing refrigerant) is preferred.
[0012]
Further, according to the present invention, the supercharger (6) for pressurizing the intake air to the intake pipe (4), the throttle valve (7) for adjusting the flow rate of the intake air, and the fuel injection valve (11) for injecting fuel. And a combustion chamber (3) in which the fuel agitated and mixed by the fuel injection valve (11) reaches, and a knocking sensor (13) for detecting abnormal fuel, and a rotation sensor for detecting the engine speed ( 15), a load (22) is connected to an output transmission system (16) provided with a continuously variable transmission (19), and a rotation sensor (18a) is provided to the load (22). In the premixed compression self-ignition engine, the supercharger (6) and the throttle valve (7) in response to signals from the knocking sensor (13), the engine rotation sensor (15), and the load rotation sensor (18a). And a fuel injection valve (11) A control device (32) for controlling the step transmission (19) is provided. The control device (32) determines whether or not there is a change in the required rotational speed of the load (22). If there is, the amount of intake air is controlled to change the engine speed, and if the knocking sensor (13) detects the occurrence of knocking in the operating state of the engine, the engine speed is decreased or the continuously variable transmission (19 ) To guarantee the rotational speed of the load (22). If knocking is not suppressed, the engine speed is further reduced. If knocking is suppressed, the engine output that requires the load is insufficient. If the engine output is insufficient, the fuel supplied to the engine is increased to increase the torque, and the knocking sensor does not detect the occurrence of knocking or the engine output is not insufficient. Can have a function to determine whether the response to the required rotational speed of the load, when not depending controls the intake air amount, to end the work if depending.
[0013]
Furthermore, according to the present invention, a knocking sensor (13) for detecting abnormal combustion, a continuously variable transmission (19) interposed in an output transmission system (16) for transmitting engine output to the load side, In the control method of the premixed compression auto-ignition engine having the control device (32) for controlling the rotational speed and the supplied fuel amount, when the abnormal combustion is detected by the knocking sensor (13), the abnormal combustion occurs. The continuously variable transmission (19) reduces the engine speed, lowers the engine speed, increases the fuel supply amount, increases the generated torque to reduce the output fluctuation, and reduces the required engine speed on the load side. A change is detected, and when the required rotational speed on the load side changes, the intake air amount is controlled so that the engine rotational speed is changed in accordance with the changed required rotational speed on the load side.
[0014]
In the practice of the present invention, the knocking sensor (13) for detecting whether or not abnormal combustion has occurred is normally used for an acceleration sensor for detecting vibration acceleration, an in-cylinder pressure sensor using a piezoelectric element, and other knock detection. Any electromagnetic sensor may be used.
[0016]
According to the present invention having such a configuration, when abnormal combustion is detected, the number of revolutions is controlled (the number of revolutions is controlled so that the number of revolutions decreases). To increase.
If it demonstrates with reference to FIG. 3, if an operation point will be in the position of a point (P1), it will become an area | region above the abnormal combustion (knocking) limit characteristic curve (P), and abnormal combustion (knocking) will generate | occur | produce.
If the rotational speed is decreased when abnormal combustion (knocking) occurs, the operating point moves to the position indicated by the symbol (P2). Since the operating point (P2) is a region below the abnormal combustion limit characteristic curve (P), the abnormal combustion state is eliminated.
However, if the rotational speed is lowered and stays at the position of the operation point (P2), the output fluctuation becomes too large (output reduction is large), which is inconvenient.
[0017]
Here, the distance on the vertical axis between the operating point (P2) and the abnormal combustion limit characteristic curve P corresponds to the torque margin. As apparent from FIG. 3, when the operating point moves to the point (P2), the torque margin increases and the torque that can be generated increases as compared with the previous operating point P1.
Then, the torque is increased up to the operation point P3. By increasing the torque from the point (P2), the output fluctuation range is decreased.
More specifically, since “the number of revolutions” × “torque” = “output”, the output increases as the torque increases, and the output fluctuation decreases.
[0018]
In the present invention, when reducing the rotational speed of the premixed compression self-ignition engine, a transmission means is provided in the output transmission system from the engine output to the load side so as not to fluctuate the rotational speed of the load side. Must be changed.
Here, the rotational speed on the load side hardly changes even if the gear ratio of the transmission means is changed, and if it converges to a constant rotational speed (such a “load” includes, for example, a generator, The above-mentioned control is preferably performed) (a compressor for compressing a refrigerant of a gas heat pump or the like is assumed).
[0021]
According to the present invention, the present invention can be applied even when the rotational speed on the load (21) side changes without converging on a constant rotational speed.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
1 and 2 show a first embodiment of the present invention.
In the block diagram of the first embodiment shown in FIG. 1, a fuel injection valve 11 as a fuel supply means is provided in an intake pipe 4 of a premixed compression auto-ignition engine (hereinafter abbreviated as an engine) 2, and a signal line The controller 30 communicates with the controller 30a. The fuel injection valve 11 is provided so that the injected fuel can be sufficiently premixed before it reaches the combustion chamber 3 after being agitated and mixed with the intake air Air.
[0023]
The cylinder head 2a at the upper part of the combustion chamber 3 of the engine 2 is provided with a knocking sensor 13 as detection means for detecting abnormal combustion of the engine (hereinafter abbreviated as knocking), and communicates with the control device 30 by a signal line 13a. . The knocking sensor 13 may be any of an acceleration sensor that detects vibration acceleration, an in-cylinder pressure sensor that uses a piezoelectric element, an electromagnetic sensor, and the like.
The acceleration sensor can be attached to the cylinder block, and the in-cylinder pressure sensor may be attached only to the cylinder head.
[0024]
The engine 2 is provided with a rotation sensor 15 for detecting the engine speed, and communicates with the control device 30 through a signal line 15a.
[0025]
Further, a load generator 21 is communicated with the engine 2 via the output transmission system 16. The output transmission system 16 includes a first shaft 17 that is directly connected to the engine 2, a continuously variable transmission 19 that is a transmission means, and a second shaft 18, and the continuously variable transmission 19 is the same as that of the first shaft 17. The rotation speed is continuously variable, and the rotation speed of the second shaft is converged to a torque required by the generator 21 and a constant rotation speed.
As with the generator 21, a compressor for GHP (gas heat pump) refrigerant compression that converges at a constant rotational speed even when the transmission gear ratio is changed is a suitable load target.
[0026]
The transmission 19 is communicated with the control device 30 via a signal line 30b, and the generator 21 is communicated with the control device 30 via a signal line 21a.
The control device 30 receives the detection signal of the knocking sensor 13 and changes the engine speed, the fuel supply amount, and the transmission gear ratio of the transmission 19 to avoid knocking and suppress fluctuations in the engine output to the generator 21. It has the function to control to do.
[0027]
The operation of the first embodiment having the above-described configuration will be described with reference to the control flowchart of FIG. 2 and FIG. 3 showing the point for controlling knocking.
Step S1 indicates that the engine 2 is in an operating state and is in a routine for detecting the occurrence of knocking.
[0028]
Step S2 is a step of detecting and confirming the occurrence of knocking (a step of detecting the occurrence of knocking). In the “N” state where the occurrence of knocking is not detected, the system loops and waits. If knocking occurs and the detection confirmation is “Y”, the process proceeds to step S3. The knocking occurrence point at this time is the operation point P1 in the knock region in FIG.
(N1, T1).
[0029]
In step S3, in order to avoid knocking, the transmission 19 is controlled so as to reduce the rotation speed of the first shaft 19 while keeping the rotation speed of the second shaft 18 (of the transmission 19) constant. That is, the engine speed is lowered and decelerated to the operating point P2 (n2, T2) in FIG. 3 (step of lowering the engine speed) and moved to the normal combustion region (N). And the rotation speed of the 2nd axis | shaft 18 is made constant, and the required drive rotation speed of the generator 21 is ensured.
[0030]
In step S4, it is determined whether or not the moved driving point P2 (n2, T2) avoids knocking. If it is “N” that knocking avoidance has not been completed, the process returns to step S3 to move the operation point P2 to the low speed side again. If it is “Y” in the knocking avoidance state, the process proceeds to step S5.
[0031]
In step S <b> 5, it is determined whether or not the last operating point P <b> 2 (n <b> 2, T <b> 2) that has moved to the deceleration side satisfies the engine output that matches the power required by the generator 21. If the engine output is sufficient “N”, the vehicle can be operated, and the process returns to step S1 to perform normal operation. If the engine output is insufficient “Y”, the process proceeds to step S6.
[0032]
In step S6, the fuel supplied to the engine 2 is increased to increase the torque {the step of increasing the generated torque and decreasing the output (torque × rotation speed) fluctuation}. The increase in the generated torque due to the increase in fuel supply at this time is kept within the torque margin (for example, the difference in torque between P2 and knock generation curve P in FIG. 3) due to the decrease in the rotational speed.
Then, the torque increase stays within the normal combustion region (N) without knocking and is adjusted to the power required by the generator 21 (the operating point at this time is P3 (n3, P3), and normally n3 = n2) Yes.) Return to step S1.
[0033]
As described above, normal operation that avoids knocking except for the transition time from the detection of the occurrence of knocking to the deceleration of the engine speed, the increase in the amount of fuel supply, and the guarantee that the required power of the generator 21 guarantees the engine output. Can continue.
[0034]
4 and 5 show a second embodiment of the present invention. Devices having the same form and function as those of the first embodiment will be described with the same reference numerals in principle.
In the block configuration diagram of the second embodiment shown in FIG. 4, a turbocharger 6 that pressurizes and blows intake air Air to the intake pipe 4 of the engine 2 and a throttle valve 7 that adjusts the flow rate of the intake air Air are configured. An intake air amount adjusting means 6A is provided, and a fuel injection valve 11 as a fuel supply means is provided between the intake air amount adjusting means 6A and the combustion chamber 3.
A waste gate valve or a bypass valve that controls the operation of the supercharger 6 may be added to the intake air amount adjusting means 6A.
[0035]
The fuel injection valve 11 is provided so that the injected fuel can be sufficiently premixed before it reaches the combustion chamber 3 after being agitated and mixed with the intake air Air.
The supercharger 6 is connected to the control device 32 by a signal line 32c, the throttle valve 7 is connected by a signal line 6a, and the fuel injection valve 11 is connected by a signal line 32a.
[0036]
A knocking sensor 13 as detection means for detecting knocking of the engine is provided in the cylinder head 2a at the upper part of the combustion chamber 3 of the engine 2 and communicated with the control device 32 by a signal line 13a. The knocking sensor 13 may be any of an acceleration sensor that detects vibration acceleration, an in-cylinder pressure sensor that uses a piezoelectric element, an electromagnetic sensor, and the like.
[0037]
The engine 2 is provided with a rotation sensor 15 for detecting the engine speed, and is communicated with the control device 32 by a signal line 15a.
A load 22 is communicated with the engine 2 via the output transmission system 16.
[0038]
The output transmission system 16 includes a first shaft 17 that is directly connected to the engine 2, a continuously variable transmission 19 that is a transmission means, and a second shaft 18, and the continuously variable transmission 19 is the same as that of the first shaft 17. The rotational speed of the second shaft is transmitted with the torque and the rotational speed required by the load 22 by continuously changing the rotational speed.
[0039]
The load 22 is provided with a rotation sensor 18a for detecting the number of rotations, and communicated with the control device 32 through a signal line 18b.
Although not clearly shown in FIG. 4, a change in the required rotational speed of the load 22 is detected in the control device 32 based on a signal from the rotation sensor 18a.
For example, when considering the use as a vehicle, the change detection means for the required rotational speed of the load 22 is detected by a calculation in which the rotational speed fluctuation of the load 22 is performed in the control device 32 or a change in the vehicle speed driven by the load 22. Either detection or detection from the running acceleration of the vehicle may be used. When the rate of change exceeds a predetermined value, it is preset that a response is required on the engine output side.
Here, since the means for detecting the required rotational speed of the load differs depending on the target load, it is preferable that the signal relating to the rotational speed to be set is output from the target load.
[0040]
The transmission 19 is communicated with the control device 32 by a signal line 32b, and the motor 22 is communicated with the control device 32 by a signal line 22a.
[0041]
The control device 32 gives the rotational speed according to the request that the load 22 fluctuates, receives the detection signal of the knocking sensor 13 at the rotational speed, and changes the engine rotational speed, the fuel supply amount, and the transmission gear ratio of the transmission 19. Thus, knocking is avoided, and an output of the engine 2 to the load 22 is transmitted to control to suppress output fluctuation.
[0042]
The operation of the second embodiment having the above-described configuration will be described with reference to the control flowchart of FIG. 5 and FIG. 3 showing the point for controlling knocking.
[0043]
In step S11, the power required by the load 22 is stable, and the output of the engine 2 that supplies the power indicates a state of steady operation. At this stage, there is an operation point, for example, P1 in the normal operation region (N) in FIG.
[0044]
In step S12, it is confirmed whether there is a change in the required rotational speed of the load 22 (step of detecting a change in the required rotational speed). If “N” is not requested, the process proceeds to step S14. If the request for increasing or decreasing the rotational speed is “Y”, the process proceeds to step S13.
[0045]
In step S13, the intake air amount is controlled. This is performed by means 6A for adjusting the amount of intake air (step of controlling the amount of intake air). Then, the process proceeds to step S14. Step S14 indicates that the engine 2 is in an operating state and is in a state of detecting the occurrence of knocking.
[0046]
Step S15 is a step of detecting and confirming the occurrence of knocking (a step of detecting the occurrence of knocking). If the occurrence of knocking is not detected “N”, the process proceeds to step S20. If knocking occurs and detection is “Y”, the knocking generation point is the operation point P1 (n1, T1) in the knocking region in FIG. move on.
[0047]
In step S <b> 20, it is confirmed whether or not transmission is performed according to the required rotation speed of the load 22. If it is “Y” satisfying the requirement, the process proceeds to step S21 and ends. And it returns to step S11 and waits. If “N” has not yet reached the required rotational speed, the process returns to step S13 to change the rotational speed of the engine 2 again.
[0048]
In step S16, in order to avoid knocking, the rotational speed of the first shaft 17 (of the transmission 19) is reduced, and the transmission 19 is controlled so that the rotational speed of the second shaft 18 is constant. The engine speed is lowered and decelerated to the operating point P2 (n2, T2) in FIG. 3 (step of lowering the engine speed) and moved to the normal combustion region (N). And the required drive rotation speed of the load 22 is guaranteed.
[0049]
In step S17, it is determined whether or not the moved driving point P2 (n2, T2) avoids knocking. If it is “N” that knocking avoidance has not been completed, the process returns to step S16 and the operation point P2 is moved again to the low speed side. If it is “Y” in the knocking avoidance state, the process proceeds to step S18.
[0050]
In step S <b> 18, it is determined whether or not the last operating point P <b> 2 (n <b> 2, T <b> 2) that has moved to the deceleration side satisfies the engine output corresponding to the power required by the load 22. If the engine output is satisfactory “N”, it is checked in step S20 whether or not transmission is performed at the required rotational speed of the load 22. If it is “Y” satisfying the requirement, the process proceeds to step S21 and ends. And it returns to step S11 and waits. If “N” has not yet reached the required rotational speed, the process returns to step S13 to change the rotational speed of the engine 2 again. If the engine output is insufficient “Y”, the process proceeds to step S19.
[0051]
In step S19, the fuel supplied to the engine 2 is increased to increase the torque (the step of increasing the generated torque and decreasing the fluctuation in output (torque × rotational speed)). The increase in the generated torque due to the increase in fuel supply at this time is kept within the torque margin (for example, the difference in torque between P2 and knock generation curve P in FIG. 3) due to the decrease in the rotational speed.
Then, the torque increase stays in the normal combustion region (N) without knocking and is adjusted to the power required by the load 22 (the operating point at this time is P3 (n3, P3), and usually n3 = n2) .) Return to Step S11.
[0052]
As described above, the output rotational speed of the engine 2 is adjusted according to the required rotational speed of the load 22, knocking at the adjusted engine rotational speed is avoided, and further, the engine output required for the required power is guaranteed. . Then, the engine speed is decelerated from the detection of the occurrence of knocking, the fuel supply amount is increased, and normal operation that avoids knocking is continued except for a slight transient time until the required power of the generator 21 ensures the engine output. it can.
[0053]
【The invention's effect】
The effects of the present invention are listed below.
(1) The transmission is controlled at the stage where knocking is detected by the knocking detection means, the engine side is decelerated, and the load side is set to a constant rotational speed. As a result, the operating point is shifted from the knock generation region to the normal combustion region, the rotation speed on the load side is guaranteed, and the engine output shortage due to deceleration is compensated by increasing the torque by increasing the fuel supply amount. Can guarantee. Therefore, when the load side continues a constant operation state, the load side is hardly affected except for a short time for the engine speed change and torque change.
(2) If knocking occurs, the engine speed can be reduced and the torque can be increased to guarantee the output, so that it is not necessary to take an excessive margin for the occurrence of knocking as in the prior art, and the output can be increased in normal operation.
(3) In the second embodiment, the control of the rotational speed and torque can be applied even when the load-side required output changes at any time, so that it can be applied to a motor for a vehicle having a large rotational fluctuation.
[Brief description of the drawings]
FIG. 1 is a block configuration diagram showing a first embodiment of the present invention.
FIG. 2 is a control flowchart of the first embodiment.
FIG. 3 is a rotation speed-torque characteristic diagram showing the point of control for suppressing abnormal ignition.
FIG. 4 is a block diagram showing a second embodiment of the present invention.
FIG. 5 is a control flowchart of the second embodiment.
FIG. 6 is an intake stroke diagram of a combustion cycle of a conventional premixed compression auto-ignition engine.
FIG. 7 is a compression stroke diagram of a combustion cycle of a conventional premixed compression auto-ignition engine.
FIG. 8 is a combustion / expansion stroke diagram of a combustion cycle of a conventional premixed compression auto-ignition engine.
FIG. 9 is an exhaust stroke diagram of a combustion cycle of a conventional premixed compression auto-ignition engine.
FIG. 10 is a characteristic diagram showing the range of occurrence of abnormal ignition.
[Explanation of symbols]
2 ... Premixed compression auto-ignition engine 4 ... Intake pipe 5 ... Exhaust pipe 6A ... Intake air amount adjusting means 6 ... Blower 7 ... Throttle valve 11 ... Fuel supply means (fuel injection valve)
13. Abnormal combustion detection means (knocking sensor)
15 .. Number of rotation detection means (rotation sensor)
15a ·· · Rotational speed change detecting means 16 · · Output transmission system 17 · · First shaft 18 · · · Second shaft 19 · · Shifting means (transmission)
21 .. Load (generator)
22 .... Load 30, 32 ... Control means (control device)

Claims (3)

  A fuel injection valve (11) in which fuel injected into the intake pipe (4) is mixed with intake air is provided, and a combustion chamber (3) in which the fuel stirred and mixed by the fuel injection valve (11) reaches is provided. A knock sensor (13) for detecting abnormal combustion and a rotation sensor (15) for detecting the engine speed are provided, and a load (16) is applied to the output transmission system (16) provided with the continuously variable transmission (19). In the premixed compression self-ignition engine to which 21) is connected, the fuel injection valve (11) and the continuously variable transmission are received in response to signals from the knocking sensor (13), the rotation sensor (15) and the load (21). A control device (30) for controlling the machine (19), and when the knocking sensor (13) detects the occurrence of knocking, the control device (30) controls the continuously variable transmission (19) to load The number of rotations does not change Decrease the engine speed, and then determine whether knocking has been avoided. If knocking is not suppressed, the engine speed is further decreased. If knocking is suppressed, the engine output required for the load is reduced. A premixed compression self-ignition engine having a function of determining whether or not the fuel is insufficient and, if insufficient, controlling the fuel injection valve (11) to increase fuel supply.   The intake pipe (4) is provided with a supercharger (6) for pressurizing the intake air, a throttle valve (7) for adjusting the flow rate of the intake air, and a fuel injection valve (11) for injecting fuel. The combustion chamber (3) to which the fuel mixed and agitated in (11) arrives is provided, and a knocking sensor (13) for detecting abnormal fuel and a rotation sensor (15) for detecting the engine speed are provided. In a premixed compression self-ignition engine in which a load (22) is connected to an output transmission system (16) provided with a step transmission (19), and a rotation sensor (18a) is provided at the load (22). The supercharger (6), the throttle valve (7), and the fuel injection valve (11) in response to signals from the knocking sensor (13), the engine rotation sensor (15), and the load rotation sensor (18a) With a continuously variable transmission (19) A control device (32) for controlling, and the control device (32) determines whether or not there is a change in the required rotational speed of the load (22), and if there is a change in the required rotational speed, it controls the intake air amount. If the engine speed is changed and the knocking sensor (13) detects the occurrence of knocking in the operating state of the engine, the engine speed is reduced or the continuously variable transmission (19) is controlled to load (22 ), The engine speed is further reduced if knocking is not suppressed, and if knocking is suppressed, it is determined whether the engine output that requires load is insufficient or not. If the engine output is insufficient, the fuel supplied to the engine is increased to increase the torque, and if the knocking sensor does not detect the occurrence of knocking or the engine output is not insufficient, the required rotational speed of the load Depending on whether or not to determine that, depending on when not controlling the intake air amount, the homogeneous charge compression ignition engine characterized by having a function to terminate the work if depending.   A knocking sensor (13) for detecting abnormal combustion, a continuously variable transmission (19) interposed in an output transmission system (16) for transmitting engine output to the load side, the engine speed and the amount of fuel supplied In the control method of the premixed compression auto-ignition engine having the control device (32) for controlling the non-continuous transmission (19), the occurrence of abnormal combustion is detected by the knocking sensor (13), and the abnormal transmission (19 ) To reduce the engine speed, decrease the engine speed, increase the fuel supply amount, increase the generated torque to decrease the output fluctuation, and detect the change in the required engine speed on the load side. Control of a premixed compression self-ignition engine, wherein the intake air amount is controlled so that the engine speed is changed in accordance with the changed required speed on the load side when the required speed of the engine changes Direction .

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