JPS6291626A - Compound supercharger of internal combustion engine - Google Patents

Abstract

PURPOSE:To make the control of a mechanical supercharger smooth, by providing two bypass passages bypassing the mechanical supercharger, and by disposing two shut-off valves which respond to the pressure of exhaust turbosupercharge and the opening degree of a throttle valve, in bypass passages, respectively. CONSTITUTION:In an intake-air passage 14 communicated with a combustion chamber 13 in an engine body 10, there are disposed a supercharger 20 and a turbocharger 18 in series. In this arrangement, two bypass passages 38a, 38b are connected to the intake-air passage 14 upstream and downstream of the supercharger 20, and are disposed therein with shut-off valves 39a, 39b for opening and closing them. Further, during partial load operation a second actuator 80 opens the second valve 39b in accordance with the opening degree of a throttle valve 21 and in accordance with the negative pressure of intake-air at a port 87. Meanwhile during high load operation at a high rotational speed, a diaphragm 42 in a first actuator 40 is pressed by the discharge side positive pressure of the turbocharger 18 to open the first valve 39a.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a composite supercharging device for an internal combustion engine that includes an exhaust turbo supercharger and a mechanical supercharger.

[Conventional technology]

Since the exhaust turbo supercharger (turbocharger) does not operate in the low engine speed range, a positive displacement compressor (mechanical supercharger) such as a Roots pump is attached to ensure supercharging in this low speed range. A composite supercharging device is known in which both superchargers are selectively used depending on the rotational speed range to ensure supercharging over substantially the entire rotational speed range.

For example, Japanese Utility Model Application Publication No. 59-67537 discloses a composite supercharging device that performs switching according to the rotational speed.

That is, an on-off valve is installed in the bypass intake passage that bypasses the mechanical supercharger, and is closed when the engine speed is below a certain value, and is closed in the low speed range where the turbocharger does not operate. All intake air is bypassed by the on-off valve (it is sent to the sparcharger for supercharging).

In the case of a turbocharger, the supercharging pressure is controlled by opening a wastegate pulp, and in the case of a supercharger, it is controlled by opening a bypass passage connecting the front and rear parts.

Incidentally, the fuel efficiency of an internal combustion engine is better when supercharging is performed using a turbocharger than when supercharging is performed using a supercharger. This is used to drive the supercharger.
This is because a part of the output generated by the internal combustion engine is diverted. On the other hand, even in the case of an internal combustion engine equipped with both a turbocharger and a supercharger, fuel efficiency deteriorates in the operating range where the supercharger is driven.

For this reason, when the supercharging pressure increases during two-stage supercharging by both the supercharger and turbocharging, the variable transmission device reduces the speed ratio of the supercharger to reduce the load during supercharging. There is one (Japanese Patent Publication No. 46-14165), but the device is complicated and
Controlling it is also not easy.

Therefore, in Utility Application No. 60-52760, the applicant of the present application previously installed a bypass passage in the bypass passage connecting the upstream and downstream sides of the supercharger in the intake passage, which opens and closes the bypass passage according to the intake pressure of the intake manifold. ,
The present invention also discloses that by setting the opening pressure of the waste gate valve to be higher than the opening pressure of the bypass valve, the operation of the supercharger can be controlled with a simple structure to improve fuel efficiency.

[Problem that the invention seeks to solve]

However, in this composite supercharging system, as mentioned above, the intake pressure in the intake manifold part controls the opening and closing of the bypass valve of the supercharger, so when the turbocharger starts operating, the pressure in the intake manifold part rises, and the bypass valve opens. However, when the supercharger is stopped, the pressure decreases by that amount, and as a result, the bypass valve closes again.

In this way, the bypass valve repeatedly opens and closes, which may cause intake pressure hunting and engine torque hunting.

Furthermore, in the above configuration, the bypass valve does not open during partial load, so there is a problem that the supercharger cannot be stopped and driving loss increases.

゛In view of the above-mentioned problems, the object of the present invention is to improve fuel efficiency and drivability by smoothly controlling the opening and closing of the bypass valve during partial load and full load, that is, controlling the supercharger, and to solve the above-mentioned problems. The goal is to eliminate it.

[Means for solving problems]

In order to achieve the above object, the present invention includes an exhaust turbo supercharger that operates mainly in the high engine speed range in the intake passage, and a mechanical supercharger that mainly operates in the low engine speed range downstream thereof. In a composite supercharging system for an internal combustion engine in which the mechanical supercharger is arranged in series, first and second intake bypass passages are provided to bypass the mechanical supercharger, and the first intake bypass passage is provided with an exhaust turbocharging pressure. A first opening/closing control valve responsive to throttle opening is provided, and a second opening/closing control valve responsive to throttle opening is provided in the second intake bypass passage.

〔Example〕

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows an embodiment of a composite supercharging device according to the present invention, in which a supercharger 20 such as a Roots pump and a turbocharger 18 are connected in series in an intake passage 14 communicating with a combustion chamber 13 of an engine body 10. established in

The air cleaner 16 is provided at the most upstream side of the intake passage 14, and the air flow meter 17 is provided at the downstream side thereof.

A compressor 19 of the turbocharger 18 is provided further downstream, and a supercharger 20 is provided downstream of the compressor 19. The throttle valve 21 is provided downstream of the supercharger 20 and changes the flow path area within the intake passage 14 in conjunction with an accelerator pedal 61 (FIG. 3) via an accelerator wire 63.

On the other hand, a turbine 25 of the turbocharger 18 is provided in the middle of the exhaust passage 15, and an exhaust bypass passage 26 that bypasses the turbine 25 is formed. In the turbocharger 18, a turbine 25 is rotationally driven by the exhaust gas passing through the exhaust passage 15, and thereby the compressor 1
9 rotates to increase the pressure of air taken in from the intake passage 14. wastegate pulp 27
opens and closes the exhaust bypass passage 26 to adjust the amount of exhaust gas supplied to the turbine 25 and control the rotation of the turbocharger 18. The actuator 28 that drives the wastegate pulp 27 to open and close has a conventionally known configuration and has a pressure chamber 31 defined by a diaphragm 30. In this pressure chamber 31, a passage downstream of the compressor is provided via a passage 32. It is connected to the intake passage portion 67 so that turbo boost pressure is transmitted thereto. When the pressure in the pressure chamber 31 overcomes the elastic force of the spring 33, the wastegate pulp 27 opens the bypass passage 26, controls the exhaust gas passing through the turbine 25, and controls the compressor 19 of the turbocharger 18. Keep the outlet pressure constant.

Air supercharged by turbocharger 18 flows into supercharger 20 . A drive shaft of the supercharger 20 is connected to a pulley 35 having an electromagnetic clutch,
This pulley 35 is connected to a crank pulley 36 provided on the engine body 10 by an endless belt 37. Therefore, supercharger 20 is driven via crank pulley 36 when the electromagnetic clutch is in the engaged state. According to the present invention, the upstream and downstream sides of the supercharger 20 of the intake passage 14 are provided with two intake bypass passages 38.
a, 38b, and first and second bypass pulps 39a, 39b for opening and closing the first and second bypass passages 38a, 38b are provided in the first and second bypass passages 38a, 38b. The first actuator 40 that opens the first bypass valve 39a is configured by partitioning the inside of the shell 41 with a diaphragm 42 to form a pressure chamber 43.
2 is connected to the first bypass valve 39a. Pressure chamber 4
3 is connected to an intake passage (port) 71 upstream of the supercharger via a pressure pipe 45. When this pressure overcomes the elastic force of the spring 44 provided in the chamber on the opposite side of the pressure chamber 43, the first bypass valve 39a opens the first bypass passage 38.

The second actuator 80 that opens and closes the second bypass valve 39b is constituted by a diaphragm device similar to the first actuator 40, and the inside of the shell 81 is connected to a diaphragm 82.
A pressure chamber 83 defined by a diaphragm 82
is connected to the second bypass valve 39b. Pressure chamber 83
is connected to an intake passage (port) 87 downstream of the throttle valve 21 via a pressure line 85. When the intake negative pressure of the boat 87 overcomes the spring 84 provided in the pressure chamber 83, it pulls the diaphragm 82 and opens the second bypass valve 39.
Open b.

Incidentally, the intake negative pressure of the boat 87 is detected by a pressure sensor 92, and the opening/closing of the first bypass valve 39a is detected by a known opening/closing detection switch 93 (for example, a known throttle opening sensor can be used), respectively. ,S,
The signal is input to an electronic control section 50 equipped with a microcomputer.

The electromagnetic clutch of the supercharger 20 is controlled by the electronic control unit 50.
Switching is controlled by. The electronic control unit 50 receives a negative pressure signal 8 (engine load signal) sr input from a load sensor, that is, a pressure sensor 91 for intake negative pressure during high-load operation when the throttle valve 21 is opened, and an open/close detection switch for the first bypass valve 39a. Based on the output signal S from 93, the pulley 3
Output ON and OFF commands to 5, connect the electromagnetic clutch,
make them leave. However, the rotor 2 of the supercharger 20
0a and 20b are rotated by the rotation of the crank pulley 36 and start supercharging, or are connected to the crank pulley IJ.
36 rotation and stops supercharging. Now, at partial load (throttle opening is below a predetermined value), boat 87
The second diaphragm actuator 80 is activated by negative intake pressure.
opens the second bypass valve 39b. On the other hand, this intake negative pressure is detected by the pressure sensor 91, and the computer 50 disconnects the electromagnetic clutch of the supercharger 2.0 to stop the supercharger. (Steps 301 and 304 in Figure 3). Note that during this partial load, the turbocharger 18 does not perform supercharging, so the pressure at the port 71 is approximately atmospheric pressure, so the first actuator 40 does not operate and the first bypass valve 39a remains closed. That is, during partial load, the position is shown in FIG. 2A.

Furthermore, during high loads, in the low rotation range where the turbocharger does not operate, the discharge pressure of the turbocharger is approximately atmospheric pressure, similar to that during partial loads, and the intake pressure of the boat 87 is controlled by the supercharger (a supercharger is a pressure When the pressure value detected by the sensor 91 is greater than or equal to a predetermined value, the computer 5
0 (turns ON (steps 302 and 303)), the second actuator
0 is not operated and the second bypass pulp 39b is
Occupy the position shown in the figure.

Further, in a high load and high rotation range, when the turbocharger 18 starts to operate, the pressure on the discharge side of the turbocharger becomes positive, so the diaphragm 42 of the first actuator 40 is pushed and the first bypass valve 39a opens. At the same time, the detection switch 93 detects that the first bypass valve 39a is "open", and accordingly the electromagnetic clutch of the supercharger 20 is disengaged to stop the supercharger and switch to supercharging using only the turbocharger (step 304). . That is, the state shown in FIG. 2C is reached.

FIG. 4 shows a different embodiment from FIG. 1, in which the second actuator that opens and closes the second bypass valve 39b is a link 97 that is linked to the movement of the accelerator pedal 61 or the throttle valve 21. It differs from FIG. 1 in that it is constructed by . In addition, in FIG. 4, instead of detecting the negative pressure of the intake negative pressure boat 87 with the sensor 91, the opening of the throttle valve 21 is directly detected with the throttle valve opening sensor 99.
The intake negative pressure sensor in the figure is also equivalent to detecting the throttle opening. Outside the above points, the embodiment shown in Fig. 4 is the first
It has exactly the same configuration as the embodiment shown in the figure. Regarding the operation, when the supercharger is operated under the conditions shown in Fig. 1, the intake negative pressure is below a predetermined value, whereas in Fig. 4, the conditions for operating the supercharger are as follows, except that the throttle valve opening is above the predetermined value. 1 and 3 are similar, so the explanation of the operation with respect to FIG. 4 will be omitted.

〔Effect of the invention〕

As described above, according to the present invention, two bypass valves are provided for the supercharger, one of which is provided with a bypass valve that opens according to the discharge pressure of the turbocharger, and the other that opens according to the throttle valve opening. By providing the bypass valve, fuel efficiency and drivability can be improved by smoothly controlling the opening and closing of the bypass valve under partial load and full load, that is, controlling the supercharger.

[Brief explanation of drawings]

FIG. 1 is an illustrative diagram showing the overall structure of a composite supercharging device according to the present invention, FIGS. 2A to 2C are diagrams showing various operating positions of two bypass valves in the device shown in FIG. 3
1 is a diagram showing an operation flowchart of the supercharging device shown in FIG. 1, and FIG. 4 is a diagram similar to FIG. 1 showing a different embodiment from FIG. 1. 14... Intake passage, 15... Exhaust passage, 18... Turbocharger, 20... Supercharger, 25... Turbine, 27... Waste gate valve, 38a, 38b... Bypass passage , 39a, 39b... bypass valve.

Claims (1)

[Claims] In a composite supercharging system for an internal combustion engine, in which an exhaust turbo supercharger that operates mainly in a high engine speed range is arranged in an intake passage, and a mechanical supercharger that mainly operates in a low engine speed range downstream of the exhaust turbo supercharger is arranged in series in an intake passage, First and second bypassing the mechanical supercharger
an intake bypass passage, a first opening/closing control valve responsive to exhaust turbo boost pressure is disposed in the first intake bypass passage, and a second opening/closing control valve responsive to throttle opening is disposed in the second intake bypass passage. A composite supercharging device for an internal combustion engine characterized by being equipped with a valve.