JPH0614035Y2 - Combined supercharger for internal combustion engine - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention includes a turbocharger and a supercharger.
The present invention relates to a combined supercharging device for an internal combustion engine that supercharges intake air by two superchargers.

[Conventional technology]

Conventionally, there is known a configuration in which a turbocharger is provided on the upstream side of the intake passage and a supercharger is provided on the downstream side (for example, Japanese Patent Laid-Open No. 61-169239). The supercharger is stopped, and the bypass passage connecting the upstream side and the downstream side of the supercharger is opened. With this configuration, the supercharging effect is obtained mainly by the supercharger in the low rotation speed range of the engine and by the turbocharger in the high rotation speed range, and the responsiveness of the supercharging effect is improved. On the other hand, the rotor surface of the supercharger is usually coated with a synthetic resin in order to reduce frictional resistance during rotation and improve durability.

[Problems to be solved by the device]

However, since the temperature of the air discharged from the turbocharger becomes high in the high load and high rotation range of the engine,
In the composite supercharger as described above, there is a problem that a part of the high temperature air may flow into the supercharger and melt the resin coating layer of the rotor.

An object of the present invention is to provide a composite supercharging device in which the synthetic resin layer on the rotor surface of a supercharger is not melted and damaged by high temperature air when the engine is under high load and high rotation.

[Means for Solving the Problems]

The combined supercharging device for an internal combustion engine according to the present invention is provided with a turbocharger on the upstream side of the intake passage and a supercharger on the downstream side, and the rotor of the supercharger has a surface made of synthetic resin. And a bypass passage connecting the upstream side and the downstream side of the supercharger of the intake passage, and a connecting portion of the intake passage and the bypass passage, which is provided at an upstream side portion of the supercharger. And a temperature determination means for determining whether or not the discharge air temperature of the turbocharger is higher than the melting temperature of the synthetic resin, and the changeover valve determines that the discharge air temperature is higher than the melting temperature. When the determination is made, the bypass passage is opened and the intake passage is closed.

[Action]

When the discharge air temperature of the turbocharger is higher than the melting temperature of the synthetic resin that forms the rotor surface of the supercharger, the bypass passage is opened by the switching valve and the intake passage is blocked upstream of the supercharger. Is supplied to the combustion chamber through the bypass passage without flowing into the supercharger.

〔Example〕

 The present invention will be described below with reference to illustrated embodiments.

FIG. 1 shows an internal combustion engine to which an embodiment of the present invention is applied.
In the figure, a piston 12 is slidably supported in a cylinder bore 11 formed in an engine body 10, and a combustion chamber 13 is formed above the piston 12. An intake passage 14 and an exhaust passage 15 communicate with the combustion chamber 13.

The air cleaner 16 is provided on the most upstream side of the intake passage 14, and the air flow meter 17 is provided on the downstream side thereof.
Further, a compressor 19 of the turbocharger 18 is provided on the downstream side, and a supercharger 20 is provided on the downstream side of the compressor 19. The surfaces of the rotors 20a and 20b of the supercharger 20 are covered with synthetic resin. The throttle valve 21 is provided between the intercooler 22 and the surge tank 23, and changes the flow passage area in the intake passage 14 in conjunction with an accelerator pedal (not shown). A surge tank 23 is formed in the intake passage 14 downstream of the supercharger 20.

On the other hand, a turbine 25 of the turbocharger 18 is provided in the middle of the exhaust passage 15, and a bypass passage 26 that bypasses the turbine 25 is formed. In the turbocharger 18, the turbine 25 is rotationally driven by the exhaust gas passing through the exhaust passage 15, whereby the compressor 19 is rotated and the pressure of the air sucked from the intake passage 14 is increased. The wastegate valve 27 opens and closes the bypass passage 26 to adjust the amount of exhaust gas supplied to the turbine 25, and controls the rotation of the turbocharger 18. The actuator 28 that drives the waste gate valve 27 to open and close has a conventionally known configuration.
A pressure chamber 31 is formed by partitioning the inside of the chamber 9 with a diaphragm 30, and the pressure in the surge tank 23 is transmitted to the inside of the pressure chamber 31 via a passage 32. Then, when the pressure in the pressure chamber 31 overcomes the elastic force of the spring 33, the waste gate valve 27 opens the bypass passage 26, suppresses the exhaust gas passing through the turbine 25, and exits the compressor 19 of the turbocharger 18. Keep the pressure constant.

The air supercharged by the turbocharger 18 flows into the supercharger 20. Supercharger 20
The drive shaft of is connected to a pulley 35 having an electromagnetic clutch, and this pulley 35 is connected to a crank pulley 36 provided in the engine body 10 by an endless belt 37. Therefore, supercharger 20 is driven via crank pulley 36 when the electromagnetic clutch is engaged. The upstream side and the downstream side of the supercharger 20 of the intake passage 14 are connected by a bypass passage 38,
A three-way switching valve 39 is provided at a connecting portion between the intake passage 14 and the bypass passage 38 and on an upstream side portion of the supercharger 20.
Is provided. This switching valve 39 is provided with an actuator 40.
Is driven to open and close by selectively opening the intake passage 14 and the bypass passage 38. As the actuator 40, for example, a step motor or a diaphragm type actuator having a conventionally known structure can be used. The actuator 40 and the electromagnetic clutch are controlled by the electronic control unit 50.

2 and 3 are enlarged views of one embodiment of the switching valve 39. The switching valve 39 includes a rectangular valve plate 39a that opens and closes the intake passage 14, and a shaft 39b fixed to the valve plate 39a. The shaft 39b includes an intake pipe 14a forming the intake passage 14 and a bypass pipe forming the bypass passage 38.
It is rotatably supported at the corner of the connecting portion with 38a, and is rotationally driven by the actuator 40. The valve plate 39a closes the bypass passage 38 to open the intake passage 14 when it is in the horizontal position as shown by the solid line in the figure, and closes the intake passage 14 when it is in the vertical position as shown by the two-dot chain line. To open the bypass passage 38.

4 and 5 show an enlarged view of another embodiment of the switching valve 39. In this embodiment, the valve plate 39a is a disc and the shaft 39b extends horizontally through the center of the valve plate 39a. The shaft 39b passes through the center of the connecting portion of the intake pipe 14a and the bypass pipe 38a, is rotatably supported by this connecting portion, and is rotationally driven by the actuator 40. Valve plate 39a
In the drawing, the bypass passage 38 is closed to open the intake passage 14 when it is inclined to the right as indicated by the solid line, and the intake passage 14 is opened when it is inclined to the right as indicated by the double-dotted line. It closes and opens the bypass passage 38.

The electronic control unit 50 includes a microcomputer, controls the opening / closing of the switching valve 39 according to the engine speed and the intake air temperature, and controls the electromagnetic clutch of the pulley 35 to be turned on and off. The electronic control unit 50 includes a central processing unit (CPU) 51,
It has a memory 52, an input port 53, and an output port 54, which are interconnected by a bus 55. The output port 54 is connected to the electromagnetic clutch of the pulley 35 and the actuator 40. The input port 53 is connected to a rotation speed sensor 41 that detects the engine rotation speed and a temperature sensor 42 that is provided in the intake passage 14 to detect the discharge air temperature of the turbocharger 18.

FIG. 6 shows the electromagnetic clutch of the pulley 35 and the switching valve 39.
The control routine of is shown. This control routine is interrupted every predetermined time.

At step 101, it is judged if the engine speed Ne is higher than 3000 rpm. If it is higher than this, step 104
If it is lower than this, proceed to step 102. That is, when the engine is operating at 3000 rpm or less, the electromagnetic clutch is engaged in step 102, and the switching valve 39 is switched in step 103 to close the bypass passage 38 and open the intake passage 14. As a result, the supercharger 20 is driven, and all intake air is supplied to the supercharger 20 to perform sufficient supercharging. On the other hand, when the engine speed Ne is higher than 3000 rpm, the electromagnetic clutch is disconnected in step 104, and the switching valve 39 is switched in step 105 to open the bypass passage 38 and close the intake passage 14. As a result, the supercharger 20 is stopped, and all the intake air bypasses the supercharger 20 and flows in the bypass passage 38.

Then, in step 101, the engine speed N
When e is higher than 3000 rpm, it is determined that the temperature of the air discharged from the turbocharger 18 is higher than a predetermined value, that is, 150 ° C, the supercharger 20 is stopped, and hot air is prevented from being supplied to the supercharger 20. To be done. Therefore, the rotor of supercharger 20 is not exposed to high temperature air, and the synthetic resin layer coated on the surface of the rotor is prevented from being melted and damaged.

FIG. 7 shows the electromagnetic clutch of the pulley 35 and the switching valve 39.
Another example of the control routine of FIG. This control routine
Except that step 111 is performed before step 102,
This is the same as the control routine of FIG. Well, step 10
When the engine speed Ne is 3000 rpm or less in 1, the routine proceeds to step 111, where it is judged if the discharge air temperature T of the turbocharger 18 detected by the temperature sensor 42 is higher than 150 ° C. This discharge air temperature T is 150 ° C
When it is higher, steps 104 and 105 are executed, the electromagnetic clutch is disengaged, and the switching valve 39 is switched. That is, the switching valve 39 closes the intake passage 14 and opens the bypass passage 38. As a result, the supercharger 20 is stopped and high temperature air is prevented from being supplied to the supercharger 20, so that the rotor of the supercharger 20 is not exposed to the high temperature air and the synthetic resin layer on the rotor surface melts. Loss is prevented.

Then, in the control routine of FIG. 7, the engine speed is 30
Even when the discharge air temperature T is 150 rpm or less, when the discharge air temperature T exceeds 150 ° C., the high temperature air is prevented from flowing into the supercharger 20, and more reliably than the control routine of FIG. , 20b of the synthetic resin layer are prevented from being melted.

As a means for determining whether or not the discharge air temperature of the turbocharger 18 has exceeded a predetermined value, the magnitude of the engine load represented by the ratio of the intake air amount Q and the engine speed Ne is determined. Good.

〔effect〕

As described above, according to the present invention, it is possible to prevent the synthetic resin layer on the rotor surface of the supercharger from being melted and damaged by the hot air discharged from the turbocharger. That is, the temperature of the air flowing into the supercharger is kept low, the synthetic resin layer on the rotor surface is not required to have high heat resistance, and the rotor is easily manufactured.

[Brief description of drawings]

FIG. 1 is a sectional view showing an engine to which an embodiment of the present invention is applied, FIG. 2 is a sectional view showing a switching valve in the embodiment of FIG. 1, and FIG. 3 is a front view of the switching valve of FIG. FIG. 4 is a sectional view showing another embodiment of the switching valve, FIG. 5 is a front view of the switching valve of FIG. 4, and FIG. 6 is a flowchart of an embodiment of a control routine for controlling the switching of the switching valve. FIG. 7 is a flow chart of another embodiment of the control routine for controlling the switching of the switching valve. 14 ... Intake passage, 18 ... Turbocharger, 20 ... Supercharger, 20a, 20b ... Rotor, 38 ... Bypass passage, 39 ... Switching valve, 42 ... Temperature sensor.

Claims (1)

[Scope of utility model registration request] 1. A composite supercharger for an internal combustion engine, wherein a turbocharger is provided upstream of an intake passage and a supercharger is provided downstream thereof, and a rotor of the supercharger has a surface made of synthetic resin. A bypass passage connecting the upstream side and the downstream side of the supercharger of the intake passage, a switching valve provided at an upstream side portion of the supercharger at a connecting portion between the intake passage and the bypass passage, and the turbocharger. Temperature change means for judging whether or not the discharge air temperature of the charger is higher than the melting temperature of the synthetic resin, and the switching valve, when the discharge air temperature is judged to be higher than the melting temperature, the bypass valve. A composite supercharging device for an internal combustion engine, which opens the passage and closes the intake passage.