JPS6232225A - Engine provided with exhaust turbo-supercharger - Google Patents

Abstract

PURPOSE:To aim at enhancing the economy of fuel consumption and the output of an engine, by providing a second bypass passage to a specified engine cylinder, bypassing a turbine in a supercharger and a bypass passage bypassing the supercharger, and by disposing a valve mechanism adapted to open at a predetermined timing in the second bypass passage. CONSTITUTION:In an engine in which a waste gate valve 9 opening and closing in accordance with the supercharged pressure is disposed in a first bypass passage bypassing a turbine 5a in a supercharger 5 and connected to an exhaust passage 7, a third engine cylinder 1c is connected with a second bypass passage 10 leading exhaust gas from the third engine cylinder 1c into the exhaust passage 7, bypassing a turbine 5a and the first bypass passage 8. Further, there is provided a valve mechanism 11 composed of two valves 11A, 11B adapted to be changed over to feed exhaust gas to the turbine 5a or the first bypass passage 8 from a first engine cylinder 1a, or to feed exhaust gas directly to the exhaust passage 7 from the first engine 1c, bypassing the turbine 5a and the first bypass passage 8. Further, control is made such that the ignition timing of the engine cylinder 1c is advanced or the air-fuel ratio is lowered when the second bypass passage is opened.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an engine with an exhaust turbo supercharger. This relates to the equipped engine.

[Prior art]

BACKGROUND ART Among engines with an exhaust turbo supercharger, an engine is known in which a bypass passage that bypasses a turbine of an exhaust turbo supercharger is connected to an exhaust passage. For example, Utsukai Showa 58-2
Publication No. 0335 describes an engine in which a wastegate valve is installed in the bypass passage, which opens and closes depending on the boost pressure. By adjusting the opening of the wastegate valve according to the boost pressure, a displacement suitable for driving the turbine will be supplied. can be generated by a compressor.

However, in such an engine with an exhaust turbo supercharger,
As the engine speed increases, the displacement becomes larger and increases, so at high speeds the wastegate valve acts as exhaust throttling resistance, increasing exhaust pressure and causing pumping loss. This results in a decrease in output. On the other hand, if a large wastegate valve with low resistance is used, it is difficult to accurately control boost pressure in the low speed range.

Therefore, in Japanese Patent Application No. 60-49623, the present applicant proposed that the exhaust gas bypass the turbine and the bypass path (hereinafter referred to as the first bypass path) to a specific cylinder among several cylinders. We have proposed a valve mechanism that connects a second bypass path leading to the passage and controls the amount of exhaust gas passing through the second bypass path. According to this, it is possible to control the amount of exhaust gas discharged directly from the second bypass passage to the exhaust passage, so a large amount of exhaust gas is exhausted from the second bypass passage at high speeds, and the resistance at the waste gate valve is significantly reduced. As a result, an increase in exhaust pressure can be suppressed.

Furthermore, since a small wastegate valve can be used, the supercharging pressure can be controlled accurately in a low speed range by the wastegate valve.

In a multi-cylinder engine having such a second bypass passage, the exhaust loss is different between the cylinder in which the second bypass passage is open and the cylinder in which the second bypass passage is not provided. become. That is, in a cylinder whose exhaust gas is discharged to the turbine or the first bypass passage, the exhaust pressure thereof increases compared to a cylinder whose exhaust gas is discharged directly into the exhaust passage. As a result, in cylinders with high exhaust pressure, the temperature in the combustion chamber increases due to the amount of residual exhaust gas, reaching a state close to the knocking limit. On the other hand, in the cylinder in which the second bypass passage is opened, the temperature in the combustion chamber is lower than that in other cylinders, and there is a margin before the knocking limit. However, control of ignition timing and air-fuel ratio has conventionally been performed on all cylinders, with the cylinder having little margin up to the knocking limit as the reference. Therefore, in the cylinder in which the second bypass passage is opened, a margin is left in the knocking limit, and the room for improving fuel efficiency and output is not utilized.

[Purpose of the invention]

The present invention was made in view of such problems in exhaust turbocharged engines.The purpose of the present invention is to prevent knocking by reducing the exhaust pressure of the cylinder in which the second bypass passage is open than that of other cylinders. Focusing on the fact that there is a margin for the limit, we provide an engine with an exhaust turbo supercharger that enables independent control of each cylinder to bring it closer to its knocking limit, improving output and fuel efficiency. The purpose is to

[Structure of the invention]

Features of the invention will be explained below with reference to the reference numbers quoted in FIG. An exhaust turbo supercharger 5 that is driven by exhaust gas for supercharging is provided, and a first bypass passage 8 that bypasses the turbine 5a of the exhaust turbo supercharger 5 is provided in the exhaust passage 7.
A waste gate valve 9 is provided which opens and closes the first bypass passage 8 in response to a signal corresponding to the boost pressure. A second bypass passage 10 is connected to the specific cylinder 1c, through which the exhaust gas can bypass the turbine 5a and the first bypass passage 8 and reach the exhaust passage 7. A valve mechanism 11 is provided which is switched later than the opening operation of the waste gate valve 9 in order to send the exhaust gas of the specific cylinder 1c to the turbine 5a and the first bypass path 8 or to the second bypass path 10. A control means 17 is provided for advancing the ignition timing of the specific cylinder 1c and/or reducing the air-fuel ratio when the valve mechanism 11 opens the second bypass passage 10.

[For production]

When the engine is running at high speed, the valve mechanism 11 is switched later than the opening operation of the waste gate valve 9.
A part or all of the exhaust gas from the turbine 5a and the first
The gas bypasses the bypass path 8 and is sent directly to the exhaust path 7. At this time, the exhaust gas throttling resistance by the waste gate valve 9 interposed in the first bypass path 8 is reduced, and a decrease in output in the high speed range is avoided. At this time, the exhaust pressure of the cylinder 1c becomes lower than the exhaust pressure of the other cylinders, and the margin of the cylinder IC up to the knocking limit becomes larger than that of the other cylinders. On the other hand, the displacement amount at that time is detected from the engine rotation speed, and the displacement amount passing through the second bypass path 10 is adjusted by the valve mechanism 11 based on the detected value, but the second bypass path 10 is opened by the valve mechanism 11. At this time, the control means 17 modifies the previous ignition timing and/or injection time in the specific cylinder 1c. Therefore, the specific cylinder I
C also approaches the non-king limit, improving the output and fuel efficiency in that cylinder, and producing similar effects for the engine as a whole.

〔Example〕

FIG. 1 is a schematic diagram showing an embodiment of an engine with an exhaust turbo supercharger according to the present invention. This makes the invention 4
This is an example applied to a cylinder engine, and four cylinders 1a to 1
d are arranged in a row. Then, clean outside air is supplied to the turbocharger 5 from the intake passage 4 via the air cleaner 2 and the air flow sensor 3. The turbo supercharger 5 includes a turbine 5a that is rotated by exhaust gas from each cylinder, and a compressor 5b that is directly connected to the turbine 5a and rotates to pressurize outside air. It is supplied to each cylinder 1a to 1d via a throttle valve 6. The exhaust ports of each cylinder 1a to 1d are connected to an exhaust passage 7, and the turbine 5a is configured to be rotated by the exhaust gas. A first bypass passage 8 is connected to the exhaust passage 7 so as to bypass the turbine 5a, and the first bypass passage 8 is opened and closed by a boost pressure control signal corresponding to the boost pressure, and the first bypass passage 8 is opened and closed in response to a boost pressure control signal corresponding to the boost pressure. A waste gate valve 9 is provided to adjust the exhaust amount.

In such an engine with an exhaust turbo supercharger, the exhaust gas flows into a specific cylinder, the third cylinder IC in this example, bypasses the turbine 5a and the first bypass passage 8, and enters the exhaust passage 7. A second bypass path 10 that can be reached is connected. That is, part or all of the exhaust gas from the cylinder IC that has been sent to the turbine 5a and the first bypass passage 8 can be sent directly to the exhaust passage 7, bypassing the turbine 5a and the first bypass passage 8. It has become.

In an engine provided with such a second bypass passage 10,
The exhaust gas from the cylinder 1c is transferred to the turbine 5a or the first bypass path 8.
A valve mechanism 11 is provided which includes two valves 11A and IIB which can be switched to send the air to the exhaust gas or bypass them and directly send the air to the exhaust passage 7. This valve mechanism 11 not only performs a switching operation (similar to the waste gate valve 9 described above, but also an electronic controller 12 that calculates the actuating amount of the actuator based on the detected engine speed etc.
The opening degree of the second bypass path 10 is adjusted by the signal from
The amount of exhaust gas passing through it is controlled.

In other words, by controlling the displacement, the exhaust gas throttling resistance by the waste gate valve 9 interposed in the first bypass path 8 is reduced, and a reduction in output in the high speed range is avoided.

The electronic controller 12 receives input of air, the air flow rate from the flow sensor 3, the engine rotation speed, etc., and the above-mentioned valve 9. It controls the ignition timing and air-fuel ratio of IIA, IIB and each cylinder 1a to 1d. Then, the first section of the exhaust passage 7. Downstream of the confluence with the second bypass passage 8.10, a rectifier 13a mixes and rectifies the exhaust gas that has passed through the turbine 5a and the bypassed exhaust gas, as shown by the broken line.
Or 13b is provided. Note that the valve mechanism 11 is
In the illustrated example, two bypass valves 11A, 11
Although B is provided in the second bypass path 10 and the passage 14 leading to the turbine 5a, it may be provided only in the second bypass path 10. In the illustrated example, by adjusting the degree of opening and closing of both valves, there is an advantage that fine control of the displacement amount to the turbine 5a is possible. Incidentally, 15 and 16 in the figure are an exhaust gas purification device and a muffler provided on the downstream side of the exhaust passage 7.

FIG. 2 is a block diagram showing one embodiment of the electronic control device 12, which includes a control means 17 for controlling the air-fuel ratio. This electronic controller 12 is given a rotational speed signal from a detection section that detects the engine rotational speed, and the pulp opening/closing control means 18
It is input to the comparison section 20 and the basic injection amount calculation section 21 in . The comparison unit 20 is provided with a set value storage unit 22 that stores a predetermined valve opening setting value corresponding to the reference engine rotation speed, and by comparing the rotation speed input and the set value, The comparison output is given to the correction value calculation section 23 and the amplifier 24. The amplifier 24 amplifies this input to a predetermined level, and provides its output to an actuator 25, which, based on these inputs, operates the wastegate valve 9 and/or the bypass pulp IIA shown in FIG. IIB
Operate opening and closing. In addition, in the air-fuel ratio control in the electronic controller 12, the air flow rate is given from the air flow sensor 3 to the basic injection amount calculation unit 21.

The basic injection amount calculation section 21 calculates the basic injection amount for each cylinder based on the rotation speed and air flow rate, and its output is given to the correction section 26. The correction value calculation unit 23
It calculates a correction value for the basic injection amount that is necessary based on the bypass amount of exhaust gas of C, and the output thereof is given to the correction section 26. The correction unit 26 corrects the basic injection amount of the cylinder IC whose exhaust gas is bypassed based on the signal from the correction value calculation unit 23 so that it becomes thinner in accordance with the bypass amount, and
The basic injection amount of other cylinders is directly transmitted to the injection pulse generator 27. The injection pulse generator 27 generates injection pulses at predetermined timing, and generates injection pulses for each cylinder 1a to 1d.
The fuel injection time signal is transmitted. In addition,
In the electronic controller 12, when a means for adjusting ignition timing or both means is employed instead of means for controlling the air-fuel ratio, the signal from the basic ignition timing calculation section is corrected,
The new ignition timing is transmitted to the ignition coil via the igniter.

FIG. 3 is a cross-sectional view of an embodiment of an exhaust gas rectifying section 13b provided at the confluence of the exhaust gas that has passed through the turbine 5a and the first bypass path 8 and the exhaust gas that has passed through the second bypass path 10. In this example, a guide vane 30 for mixing and rectifying the exhaust gas is provided immediately after the merging point, but the same effect can be obtained even if a guide vane for rectifying the exhaust gas is installed in each passage before the merging point. Obtainable. That is, the composition, temperature, and flow rate of the exhaust gas from the cylinder IC and the exhaust gas that has passed through the turbine 5a are made uniform, and the gas purification in the exhaust gas purification device 15 is performed efficiently.

Note that the exhaust gas rectifying section 13a at the junction of the exhaust passage 7 and the first bypass path 8 is similarly configured.

Next, the operation of the above-described embodiment will be explained.

When the engine speed is low and the supercharging pressure is low, the bypass valve 11A is configured so that the exhaust gas from the cylinder 1c is sent to the turbine 5a together with the exhaust gas from the other cylinders 1a, lb, and ld.
11B is the switching position as shown by the solid line. In addition, the first bypass path 8 is also closed by the wastegate valve 9. At this time, the exhaust gas from all the cylinders 1a to 1d is applied to the turbine 5a, and the outside air is compressed by the compressor 5b driven by the rotation of the turbine 5a, and air is taken into each cylinder at a predetermined supercharging pressure. If the boost pressure exceeds a certain value,
The waste gate valve 9 is gradually opened in response to a drive signal from the electronic controller 12, and the amount of exhaust gas flowing into the turbine 5a is controlled. As a result, the turbine 5a rotates to maintain its supercharging pressure, and the small wastegate valve 9 accurately controls the supercharging pressure in the low speed range.

In the high speed range, excessive exhaust gas is sent to the turbine 5a, so the opening degrees of the bypass valves IIA and IIB are adjusted by a signal from the electronic controller 12. Even in this case, the rotation of the turbine 5a is set to be appropriate for the engine speed at that time, and the desired supercharging pressure is ensured by the compressor 5b. In the present invention, the basic injection amount calculation unit 21 calculates the basic injection amount for each cylinder according to the air flow rate from the air blow sensor 3 and the engine rotation speed, and the basic injection amount for each cylinder is Those ejection amounts pass through the correction section 26 as they are, and the ejection pulse generator 27
An injection signal is transmitted to each cylinder 1a, lb, and ld.

In such an operating state, part or all of the exhaust gas from the cylinder 1c is directly discharged into the exhaust passage 7, so that the exhaust pressure in that cylinder 1c becomes lower than the exhaust pressure in the other cylinders.

In cylinders 1a, 'lb, and ld, which have high exhaust pressure, the temperature in the combustion chamber rises due to the amount of residual exhaust gas and approaches the knocking limit, but in cylinder 1c, the temperature in the combustion chamber is lower than in other cylinders. , there is plenty of room up to the knocking limit. Therefore, from the time when the valve mechanism 11 opens the second bypass passage 10, the correction value is calculated by the correction value calculation unit 23 and the correction value is calculated by the correction unit 26.
is given to the cylinder IC, and the air-fuel ratio is controlled to be lean only for the cylinder IC. In that cylinder IC, a correction is made to the previous fuel injection amount, and the signal thereof is issued from the injection pulse generator 27. As a result, the cylinder 1c performs combustion in a state close to its knocking limit, improving the output and fuel efficiency of the entire engine.

FIG. 4 shows another embodiment of the above-mentioned exhaust gas rectifier. In this example, a rectifier tank 31 as shown in the figure is provided in the exhaust gas rectifier 13b. This allows the composition temperature of the exhaust gas to
The flow velocity is made uniform, and efficient exhaust gas purification in the exhaust gas purification device can be promoted. Furthermore, if a guide plate 32 is provided in the rectifying tank 31 at a right angle or inclined as shown by an imaginary line,
The mixing effect of exhaust gas can be enhanced.

In the embodiment described above, only the exhaust gas of the third cylinder is bypassed through the second bypass passage, but even in an engine with an exhaust turbo supercharger applied to multiple cylinders, each cylinder is bypassed in the same way. Air/fuel ratio and/or ignition timing control can be performed. Although a four-cylinder engine is used as an example, the present invention can be applied to a multi-cylinder engine having two or more cylinders.

〔Effect of the invention〕

As can be seen from the detailed description of the embodiments above, the present invention connects a turbine and a second bypass path that bypasses the first bypass path to a specific cylinder, and sends the exhaust gas of that cylinder to the turbine or the first bypass path. Or, in order to bypass them and directly send the exhaust gas to the exhaust passage, a valve mechanism is provided that is switched later than the opening operation of the waste gate valve, and when the valve mechanism opens the second bypass passage, Since the cylinder is equipped with a control means for advancing the ignition timing or reducing the air-fuel ratio of the cylinder, the air-fuel ratio or ignition timing of the cylinder whose exhaust gas is discharged through the second bypass passage is controlled differently from that of other cylinders. can be set. As a result, it becomes possible to control combustion up to the knocking limit in each cylinder, making it possible to improve fuel efficiency and output of the engine at high output.

[Brief explanation of the drawing]

Fig. 1 is an overall schematic configuration diagram of an engine with an exhaust turbo supercharger showing an embodiment of the present invention, Fig. 2 is a block diagram showing an embodiment of an electronic controller, and Fig. 3 is a block diagram showing an embodiment of an electronic controller. FIG. 4 is a sectional view of one embodiment of the exhaust gas rectifying section, and FIG. 4 shows a different embodiment of the exhaust gas rectifying section. IC...-specific cylinder, 5-exhaust turbo supercharger, 5a...
...turbine, 7-exhaust passage, 8-first bypass passage, 9
-Wastegate valve, 10-・Second bypass path, 1
1 - Valve mechanism, 17 - Control means. Patent applicant Mazda Co., Ltd. agent Patent attorney Katsutoshi Yoshimura (one idiot) Figure 1

Claims (1)

[Claims] (1) An exhaust turbo supercharger that is driven by exhaust gas for supercharging is provided, and a first bypass passage that bypasses the turbine of the exhaust turbo supercharger is connected to the exhaust passage, and corresponds to supercharging pressure. In an engine with an exhaust turbo supercharger, the exhaust gas is provided with a waste gate valve that opens and closes the first bypass passage in response to a signal from the engine, and the exhaust gas bypasses the turbine and the first bypass passage to a specific cylinder. A second bypass path leading to the passage is connected, and a valve mechanism is provided that is switched so that the exhaust gas from the specific cylinder is sent to the second bypass path later than the opening operation of the waste gate valve, and the valve mechanism is An exhaust turbo supercharger characterized in that the exhaust turbo supercharger is equipped with an ignition timing control device that advances the ignition timing of the specific cylinder and/or an air-fuel ratio control device that thins the air-fuel ratio when the second bypass path is opened. Engine included.