JPH0348332B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an intake system for an engine, and more particularly to an intake system for an engine that includes an intake swirl control device that controls the swirl of intake air taken into a cylinder according to the operating state of the engine. .

The above-mentioned intake swirl control device is, for example,
- As shown in Publication No. 74021, etc., the primary side intake passage is formed by dividing the intake passage downstream of the throttle valve that is operated in conjunction with the accelerator pedal.
It is provided with an auxiliary throttle valve interposed in a secondary side intake passage among the next side intake passages. The intake system of an engine equipped with the above-mentioned intake swirl control device completely closes the above-mentioned auxiliary throttle valve and supplies intake air only from the primary intake passage when the engine is idling or operating under extremely low load with a small amount of intake air. By increasing the intake flow velocity, it is possible to form a swirl in the combustion chamber and improve the combustion rate of the air-fuel mixture, thereby improving fuel efficiency. By opening the sub-throttle valve and supplying intake air from the secondary intake passage, it is possible to increase the filling efficiency and improve the output.

However, in the case of an engine intake system equipped with an intake swirl control device, when the cooler is used especially during idling, the intake air amount increases due to the cooler load, resulting in high combustion pressure. There is a drawback that the short-time combustions combine to increase the peak of the torque generated by the engine, and as a result, the rotational torque fluctuation, that is, vibration, generated at the output shaft of the engine increases, which causes discomfort to the driver and the like.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to suppress fluctuations in rotational torque in an intake system for an engine equipped with an intake swirl control device.

An intake system for an engine including an intake swirl control device that controls the swirl of intake air taken into a cylinder according to the operating state of the engine, and strengthens the intake swirl when the engine load is low.
a torque fluctuation detection means for detecting the magnitude of rotational torque fluctuation occurring on the engine output shaft in synchronization with engine explosion; The present invention is characterized by comprising a correction means for correcting the swirl of intake air controlled by the intake swirl control device in a direction of weakening it.

That is, in the engine intake system according to the present invention, the magnitude of rotational torque fluctuation occurring at the engine output shaft is detected by the torque fluctuation detection means, and then, when the magnitude of the detected rotational torque fluctuation is larger than a predetermined value, The correction means corrects the swirl of the intake air controlled by the intake swirl control device in the direction of weakening it, and when the rotational torque fluctuation becomes larger than a predetermined value as a result of the above, the combustion speed is lowered to increase the maximum generated torque. Therefore, the generation of vibration can be prevented.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An engine intake system according to a preferred embodiment of the present invention will be described below with reference to the accompanying drawings.
In the following embodiments, a case will be described in which the intake system of the present invention is incorporated into an engine with a controlled number of cylinders, but it goes without saying that the engine incorporating the intake system of the present invention is not limited to an engine with a controlled number of cylinders. It is.

FIG. 1 is a schematic diagram of an intake system for a cylinder number controlled engine according to an embodiment of the present invention, and FIGS. 2 and 3 are cross-sectional views taken along lines - and - in FIG. 1, respectively.

In the figure, the symbol E indicates a 4-cylinder engine installed in a car (not shown), and the engine E is
As will be explained in detail later, in low-load operating conditions such as idling or deceleration, only the outer cylinders, that is, the first and fourth cylinders _E1 and _E4 , operate;
Inner cylinders i.e. second and third cylinders E ₂ and
The number of cylinders is now controlled so that _E3 is deactivated.

The intake system of the engine E includes an intake pipe section 1, a carburetor 2 equipped with a throttle valve 2a, and an intake manifold 3. This intake manifold 3 includes first to fourth cylinder manifold portions 3a, which are respectively connected to the first to fourth cylinders _E1 to _E4 , respectively.
3b, 3c, and 3d.

The second and third cylinders E ₂ and
Shutter valves 4a and 4b for controlling the number of cylinders are arranged in the intake manifolds 3b and 3c of _E3 . These shutter valves 4a, 4b are
It is fixed to a common valve shaft 5, which valve shaft 5 is rotatable about its longitudinal axis. When the valve shaft 5 rotates, the shutter valves 4a and 4b simultaneously rotate and connect the second and third intake manifolds 3.
b, 3c are designed to open and close. An actuator 7, which is an electromagnetic solenoid, is operatively connected to the valve shaft 5 via a transmission mechanism 6.

This actuator 7 is connected to a cylinder number control circuit 8, receives an excitation signal _D1 from this circuit 8,
The valve shaft 5 is rotated in response to the excitation signal _D1 to close the shutter valves 4a and 4b, which are normally open. The cylinder number control circuit 8 has an engine rotation speed sensor 9 at its input terminal that detects the rotation speed of the engine E and outputs a rotation speed signal _S1 indicating the rotation speed, and an intake pipe negative pressure for detecting the engine load. A negative pressure sensor 10 detects the negative pressure and outputs a negative pressure signal _S2 corresponding to the negative pressure, and detects a cooling water temperature and outputs a water temperature signal S2 corresponding to the cooling water temperature.
The output end of the water temperature sensor 11 that outputs S ₃ is connected, and if the water temperature signal S ₃ is above a predetermined value,
And when the coordinates indicated by the rotation speed signal S ₁ and the negative pressure signal S ₂ are in the partial cylinder operation region A indicated by hatching in the cylinder number control map in FIG. 4, the excitation signal D ₁ is outputted. It's summery. As mentioned above, when the shutter valves 4a and 4b are closed, no air is taken into the second and third cylinders _E2 and E3, and therefore the cylinders _E2 and _E3 are in _a rest state.
A partial cylinder operation state occurs in which only the first and fourth cylinders E ₁ and E ₄ operate.

In FIGS. 2 and 3, reference numeral 12 indicates a cylinder block, and a piston 13 is slidably fitted into this cylinder block 12, and this piston 13 can reciprocate up and down. The size of the combustion chamber 14 formed above can be increased or decreased. An intake port 15 and an exhaust port 16 are formed in the upper part of this combustion chamber 14.
The intake manifold 3 is connected to the intake port 15.
Exhaust manifolds 17 are connected to the exhaust ports 16, respectively. The intake port 15 and the exhaust port 16 are provided with an intake valve 18 and an exhaust valve 19, respectively, and these intake and intake valves 18 and 19 are operated in synchronization with the rotation of the engine by a valve mechanism 20, respectively. It is designed to open and close at predetermined timing.

The interior of the adjacent portion of the combustion chamber 14 formed in the cylinder head 12 of the intake manifold portions 3a, 3b, 3c, and 3d includes a primary intake passage 22a whose passage area is set relatively small by a partition wall 21;
It is divided into a secondary intake passage 22b having a relatively large passage area. Secondary intake passage 2 of intake manifold portions 3a, 3b, 3c, 3d
2b is provided with sub-throttle valves 23a, 23b, 23c, and 23d that open and close the passage 22b, respectively. These sub-throttle valves 23a,
23b, 23c, 23d are fixed to a common valve shaft 24, and this valve shaft 2
4 is adapted to rotate about its longitudinal axis. Sub-throttle valves 23a, 23
b, 23c, 23d rotate at the same time when the valve shaft 24 rotates to open the secondary intake passage 22b of the intake manifold portions 3a, 3b, 3c, 3d.
It is designed to open and close. Valve shaft 2
4 is operatively connected to an actuator 26 which is an electromagnetic solenoid via a transmission mechanism 25.

This actuator 26 is connected to a sub-throttle valve control circuit 27, receives an excitation signal _D2 from this circuit 27, rotates the valve shaft ₂₄ in accordance with this excitation signal D2, and controls the sub-throttle valve 23.
The opening and closing of a, 23b, 23c, and 23d are controlled. Sub-throttle valve control circuit 27
has an input terminal connected to the negative pressure sensor 10 and an output terminal of a vibration sensor 28 that detects vibrations caused by rotational fluctuations in the generated torque of the engine E and outputs a vibration signal _S4 corresponding to the vibrations. is connected, and when the rotational torque fluctuation indicated by the vibration signal _S4 is smaller than a predetermined value, the negative pressure sensor 10
The excitation signal D ₂ is output in response to the engine load indicated by the negative pressure signal S ₂ from the engine. On the other hand, when the rotational torque fluctuation is larger than the predetermined value, the sub-throttle valve control circuit 27 sets the value of the excitation signal _D2 to the sub-throttle valve 23.
a to 23d are corrected in the opening direction, and the corrected excitation signal D ₂ ' is supplied to the actuator 26.

Next, referring to FIG. 5, the cylinder number control circuit 8
The configuration will be explained in detail.

The cylinder number control circuit 8 has first, second, and third comparators 31, 32, and 33. One input terminal of the first, second, and third comparators 31, 32, and 33 has an engine speed sensor 9 and a negative pressure sensor 10, respectively.
and the output end of the water temperature sensor 11 are connected, and the output ends of the first, second, and third set value signal generation circuits 34, 35, and 36 are connected to the other input end, respectively. First set value signal generation circuit 34
outputs a first set value signal _e1 indicating the value of the engine rotational speed to be switched to partial cylinder operation. The second set value signal generation circuit 35 outputs a second set value signal _e2 indicating the value of the intake pipe negative pressure to be switched to partial cylinder operation. The third set value signal generation circuit 36 outputs a third set value signal e ₃ indicating the temperature that indicates the boundary between the engine cold state and warm engine state.

The first comparator 31 receives the engine rotation speed signal S ₁
When is smaller than the first set value signal _e1 , a Hi signal is output, and when it is larger, a Low signal is output. The second comparator 32 outputs a Hi signal when the negative pressure signal _S2 is smaller than the second set value signal _e2 , and outputs a Low signal when it is larger.
The third comparator 33 uses the water temperature signal _S3 as the third set value signal.
e Outputs Hi signal when larger than ₃ , and outputs Hi signal when smaller
It is designed to output a low signal. That is, the third comparator 33 improves the combustibility of the engine by generating a low signal when the engine is in a cold state so as not to control the number of cylinders.

The first, second and third comparators 31, 32, 33
The output ends of are connected to the input ends of the AND circuit 37, respectively. This AND circuit 37 operates when the output signal of the third comparator 33 is in a Hi state, that is, the engine is in a warmed-up state, and the first and second
When the output signals of comparators 31 and 32 are both in the Hi state, a Hi signal is output.
That is, the AND circuit 37 determines that when both the engine speed and the intake pipe negative pressure are below the set values, that is, the relationship between the engine speed and the intake pipe negative pressure is in the partial cylinder operating region indicated by A in FIG. At some point, it outputs a Hi signal. The output terminal of this AND circuit 37 is connected to a drive circuit 38 that outputs an excitation signal D ₁ for the actuator 7.
is connected at its input end. When the drive circuit 38 receives the Hi signal from the AND circuit 37, it generates the excitation signal _D1 to excite the actuator 7, and as a result, the shutter valves 4a, 4
b is closed, air intake to cylinders E ₂ and E ₃ is stopped, and partial cylinder operation is performed by cylinders E ₁ and E ₄ .

Next, with reference to FIG. 6, the configuration of the sub-throttle valve control circuit 27 will be explained in detail.

The sub-throttle valve control circuit 27 has a sub-throttle valve opening/closing control data generator 40 that generates sub-throttle valve opening/closing control data D _S for controlling the opening/closing of the sub-throttle valves 23a to 23d. This sub-throttle valve opening/closing control data is based on the sub-throttle valve opening and intake negative pressure that can minimize fuel consumption, as explained in detail in the applicant's pending patent application. It shows the relationship. The above data is based on the experimental results of the inventors of this application, and the sub-throttle valve is kept fully closed (0°) during extremely low load operation of the engine, including idling operation with an intake negative pressure of -520 mmHg or more. By this, the fuel consumption rate can be minimized, and the most frequently used intake negative pressure -520 ~
It has been shown that during low-medium load operation of the engine in the -150 mmHg range, the fuel consumption rate in this operating range can be minimized by keeping the secondary throttle valve at a relatively low opening of, for example, 20 degrees. .

The output end of the negative pressure sensor 9 is connected to the input end of the data generator 40, and the data generator 40 receives the negative pressure signal _S1 from the negative pressure sensor 9, and receives the negative pressure signal S1 from the negative pressure sensor 9. The sub-throttle valve opening degree corresponding to the negative pressure signal _S1 is read out by comparing _S1 with the data D _S , and an opening signal indicating this sub-throttle valve opening degree is output. A drive circuit 41 is connected to the output end of the data generator 40, and this drive circuit 41
Upon receiving the opening degree signal, an excitation signal D ₂ corresponding to this signal is output to the actuator 26 .

Sub-throttle valve control circuit 2 configured as described above
According to No. 7, in the normal state, the sub-throttle valve 2
3a to 23d are appropriately controlled to open the combustion chamber 14.
It is possible to maintain an appropriate swirl and maintain good combustibility. However, as mentioned above, when the cooler is used especially when idling, the intake air volume increases due to the cooler load, resulting in high combustion pressure. This, combined with the short combustion due to the swirl described above, increases the peak of the engine's generated torque. As a result, there is a problem in that rotational torque fluctuations, that is, vibrations occurring at the engine output shaft become large.

Therefore, the sub-throttle valve control circuit 27 of the present invention
In this case, when the rotational torque fluctuation becomes larger than a predetermined value, the sub-throttle valves 23a to 23d are activated.
A sub-throttle valve opening correction circuit 42 is provided for correcting the throttle valve opening in the direction of opening, that is, in the direction of reducing swirl. This correction circuit 42 includes a low-pass filter 43 connected to the vibration sensor 28, and this low-pass filter 43 receives the vibration signal S ₄ from the vibration sensor 28 and extracts only the low frequency component from this signal S ₄ . . This low pass filter 4
3 is connected to a full-wave rectifier circuit 44. The output terminal of this full-wave rectifier circuit 44 is connected to one input terminal of a fourth comparator 45, and the other input terminal of this fourth comparator 45 is connected to a fourth set value signal generation circuit 46. is connected. This fourth set value signal generation circuit 46 generates a fourth set value signal _e4 indicating the magnitude of vibration to be subjected to swirl correction.

The comparator 45 compares the vibration signal S ₄ processed by the low-pass filter 43 and the full-wave rectifier circuit 44 with the fourth set value signal e ₄ , and outputs a Hi signal when the signal S ₄ is larger than the signal e ₄ . . The output terminal of the comparator 45 is connected to the input terminal of a set voltage generator 47 that generates a set voltage ΔD as a correction signal when the output of the comparator 45 is in the Hi state. The output end of this set voltage generator 47 is connected to one input end of an adder 48, and the other input end of this adder 48 is connected to the output end of the drive circuit 41. The adder 48 adds a set voltage ΔD, which is a correction signal, to the excitation signal D ₂ and outputs a corrected excitation signal D ₂ '.

The sub-throttle valve control circuit 27 configured as above is as follows:
When the vibration generated by the engine is small, the excitation signal is
The actuator 26 is excited and controlled by _D2 ,
Setting the opening degrees of the sub-throttles 23a to 23d,
The swirl is set to give the minimum fuel consumption rate (the combustion pressure waveform at this time is shown by the solid line in Figure 8), and when vibration occurs, such as when the cooler is operating, the corrected excitation signal _D2 ' is used to The actuator 26,
By controlling the opening degrees of the sub-throttle valves 23a to 23d to increase, the swirl is reduced, and as a result, the combustion pressure waveform changes from the sharp one shown by the solid line in FIG. 8 to the gentle one shown by the chain line. It can be changed into something. Thus, according to the sub-throttle valve control circuit 27 of the present invention, the engine E can be operated without vibration when the cooler is activated.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an intake system for a cylinder number controlled engine according to an embodiment of the present invention, FIG. 2 is a sectional view taken along the line - in FIG. 1, and FIG. 4 is a diagram showing a cylinder number control map for switching between partial cylinder operation and full cylinder operation, and FIG. 5 is a circuit diagram showing a specific electric circuit of the cylinder number control circuit. Fig. 6 is a circuit diagram showing a specific electric circuit of the auxiliary throttle valve control circuit, Fig. 7 is a graph showing auxiliary throttle valve opening/closing control data, and Fig. 8 is a normal state combustion pressure waveform and 7 is a graph showing a combustion pressure waveform when swirl correction is performed. E...Engine, 23a, 23b, 23c, 2
3d... Actuator, 27... Sub-throttle control valve, 28... Vibration sensor, 42... Sub-throttle valve opening correction circuit.

Claims (1)

[Claims] 1. In an engine intake system equipped with an intake swirl control device that controls the swirl of intake air taken into a cylinder according to the operating state of the engine and strengthens the intake swirl when the engine load is low, the engine A torque fluctuation detection means for detecting the magnitude of the rotational torque fluctuation generated on the output shaft; and upon receiving a detection signal from the torque fluctuation detection means, when the rotational torque fluctuation is larger than a predetermined value, the rotational torque is controlled by the intake swirl control device. An intake device for an engine, comprising: a correction means for correcting in a direction to weaken the swirl of intake air.