JPH02119622A - Air intake construction of engine with supercharger - Google Patents

Abstract

PURPOSE:To increase the amount of charging to improve the output of power by forming the passage section connected to both a bypass valve in a bypass passage bypassing a supercharger and an air intake passage down a supercharger so that it is set to natural frequency making dynamic supercharging at service speed range of an engine. CONSTITUTION:A mechanical supercharger 5 is provided in the source of a common air intake passage 4 to which the upstream side of branch air intake passages 3a to 3d connected to an air intake ports 2 of each cylinder 1a to 1d is collected, and a bypass passage 7 is so provided that it bypasses the supercharger. A bypass valve 8 is provided in the bypass passage 7 and its valve body 8a is opened and closed by a diaphragm type actuator 9. The bypass passage 7 is so provided that passage length and diameter of a resonant passage section 7c, connected to an air intake passage 4 down the supercharger 5 at a downstream side section separated by a bypass valve 8, is set so that its natural frequency synchronizes in the service speed range of an engine to obtain dynamic supercharger.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an intake structure in a supercharged engine equipped with a supercharger.

(Prior Art) Conventionally, as disclosed in, for example, Japanese Unexamined Patent Publication No. 82-87815, a supercharger is provided in the intake passage of an engine,
Supercharged engines are widely known in which the output torque of the engine is increased by supercharging intake air through the operation of a supercharger and increasing the amount of intake air charged into the cylinder.

Furthermore, in the above-mentioned prior art example, a bypass passage is provided that communicates the upstream and downstream intake passages of the supercharger, and this bypass passage is provided with a bypass valve that opens and closes depending on the operating state of the engine. For example, in the low engine speed range, the bypass passage is used because the supercharging pressure by the supercharger is low and sufficient intake air cannot be secured in the low engine speed range, and driving the supercharger results in an output loss. Stop driving the feeder,
The bypass valve is opened and used to supply intake air by natural suction from the bypass passage, or,
A known technique is to open a bypass valve to relieve the supercharging pressure when the supercharging pressure rises above a set value, and to regulate the upper limit of the supercharging pressure.

(Problem to be Solved by the Invention) However, in a supercharged engine equipped with a supercharger and a bypass passage as described above, when the engine is in a low load state or a low rotation state, the supercharger is not activated. When the engine is stopped or the boost pressure is low, the natural suction effect of the bypass passage alone may not be able to secure sufficient charging amount for the output performance during supercharging, or the overload may occur under high load conditions. Driving the feeder increases engine output loss, which may reduce overall efficiency.

Therefore, in view of the above circumstances, the present invention provides a supercharger that utilizes the structure of the bypass passage to obtain a dynamic effect of intake air, thereby increasing the filling amount or reducing the workload of the supercharger. The purpose of this invention is to provide an intake structure for an attached engine.

(Means for Solving the Problems) In order to achieve the above object, the intake structure of the supercharged engine of the present invention provides a bypass that communicates the upstream and downstream intake passages of a supercharger interposed in the intake passage. A passage is provided, and a bypass valve is installed to open and close this bypass passage depending on the engine operating condition.The passage part of the bypass passage that communicates with the intake passage downstream of the supercharger on the downstream side of the bypass valve is The structure is such that the natural frequency is set to perform dynamic supercharging in the rotational speed range.

(Function) In the intake structure as described above, dynamic supercharging is performed in the engine's practical rotation speed range in the bypass valve in the bypass passage that bypasses the supercharger and the passage that communicates with the intake passage downstream of the supercharger. It is set at the natural frequency, and if the natural frequency that obtains dynamic supercharging is set in the low rotation range, the turbocharger will not operate when it is stopped or when the supercharging pressure is low. On the other hand, when set to a high rotation range, the drive of the supercharger is reduced by the increase in charging amount obtained by dynamic supercharging, reducing its workload and improving efficiency. I'm trying to improve it.

(Example) Hereinafter, each embodiment of the present invention will be described along with the drawings.

Example 1 FIG. 1 shows an example of the basic configuration.

The engine body 1 has a plurality of cylinders 1a to 1d, and a branch intake passage 3 connected to the intake port 2 of each cylinder 1a to 1d.
A to 3d are gathered on the upstream side and extended further upstream by a common intake passage 4. Above intake passage 4
A mechanical supercharger 5 for supercharging intake air is interposed in the middle. The supercharger 5 is constituted by an air pump driven by the output of the engine 1, and its operation is controlled by an electromagnetic clutch (not shown) or the like so that the drive is stopped when the engine is in a low rotation state. A throttle valve 6 is interposed in the intake passage 4 upstream of the supercharger 5.

Further, a bypass passage 7 is provided, which has an upstream end 7a and a downstream end 7b connected to the intake passage 4 on the upstream side and the downstream side of the supercharger 5, and bypasses the supercharger 5. A bypass valve 8 for opening and closing the bypass passage 7 is interposed near the upstream connecting portion 7a of the supercharger 5 of the bypass passage 7. This bypass valve 8 is installed so that a valve body 8a which opens and closes the passage receives the pressure in the opening direction of the intake passage 4 downstream of the supercharger 5 downstream of the bypass passage 7, and the valve body 8a is connected to a diaphragm type actuator 9. Opening and closing operations are supported by the This actuator 9 is equipped with a spring 9a that biases the valve body 8a in the closing direction, and negative intake pressure in the intake passage 4 downstream of the throttle valve 6 and upstream of the supercharger 5 is applied to the valve body 8a against the spring 9a. is introduced by the negative pressure passage 9b so as to operate in the opening direction.

On the other hand, the bypass passage 7 is a downstream portion partitioned by the bypass valve 8, and a resonance passage portion 7c communicating with the intake passage 4 downstream from the supercharger 5 has a passage length and a diameter (cross-sectional area) of: Its natural frequency is set to synchronize within the engine's practical rotational speed range to obtain dynamic supercharging. The tuned rotation speed is set in a low rotation range where the drive of the supercharger 5 is stopped, or it is set in a high rotation range and the drive rotation speed of the supercharger 5 is suppressed in this tuned rotation range. The torque may also be reduced.

In addition, when setting the above-mentioned synchronized rotation speed to a low rotation range, in this state, it is the time to open the bypass valve 8 and introduce intake air from the bypass passage 7 by natural suction, and the valve body 8a of the bypass valve 8 is opened. When the resonant passage portion 7C is opened to a large opening degree, the resonant passage portion 7C is opened and its function as a resonant portion for obtaining dynamic supercharging is reduced.
The opening degree of the bypass valve 8 is set low enough to allow intake air to be supplied, and the resonant passage portion 7 downstream of the bypass valve 8 is
C is substantially configured as the volume for obtaining dynamic supercharging.

To explain the operation of this example, under normal operating conditions, the driving force of the engine 1 drives the supercharger 5 to supercharge intake air and supply it to each cylinder 1a to 1d. get the output. Further, when the supercharging pressure becomes excessive, the bypass valve 8 is opened to relieve the supercharging pressure and regulate its upper limit.

In a low rotation state, the rotation speed of the supercharger 5 decreases, the boost pressure is low, and the drive loss increases, so the drive of the supercharger 5 is stopped, and the large intake negative pressure of each cylinder 1a to 1d is reduced. It also acts on the intake passage 4 on the upstream side of the turbocharger 5, increasing the intake negative pressure, and this negative pressure is introduced into the actuator 9 through the introduction passage 9b, causing the valve body 8a of the bypass valve 8 to open. Then, intake air is supplied from a bypass passage 7 that bypasses the supercharger 5, and air is taken into each cylinder 1a to 1d by natural intake in a state where the supercharger 5 does not create passage resistance.

If the natural frequency of the resonance passage section 7C of the bypass passage 7 is set to be synchronized in the low rotation region as described above, the filling amount is increased by dynamic supercharging of intake air at the tuning point. This will improve output performance.

In addition, if the tuning point of the natural frequency of the resonance passage section 7C of the bypass passage 7 is set in the high rotation region where supercharging is performed by the supercharger 5, dynamic supercharging is performed at this tuning point. There is an increase in the charging amount, and it is possible to reduce the supercharging pressure by the supercharger 5 by the increase in the charging amount obtained by this dynamic supercharging, reducing the drive by the engine of the supercharger 5 and reducing its work. can be reduced.

Embodiment 2 This embodiment is shown in FIG. 2, and is an example in which the tuning point of dynamic supercharging using a bypass passage can be switched to a plurality of stages.

Branch intake passages 3a to 3d connected to the intake boat 2 of each cylinder 1a to 1d of the engine main body 1 are collected on the upstream side thereof and extended further upstream by a common intake passage 11. A mechanical supercharger 5 for supercharging intake air is installed in the middle of the intake passage 11, as in the previous example. A throttle valve 6 is interposed in the intake passage 11 upstream of the supercharger 5.

Further, the bypass passage 12 that bypasses the supercharger 5 has an upstream end 12a connected to the intake passage 11 upstream of the supercharger 5, and a downstream end 12b connected to the intake passage 11 upstream of the supercharger 5 and for each of the cylinders 1a to 12. Branch intake passage 3 connected to intake boat 2 of 1d
It is connected to the downstream side of the gathering parts a to 3d.

Upstream connecting portion 12 of the bypass passage 12 to the supercharger 5
A bypass valve 8 for opening and closing the passage 12 is located near a.
is interposed. This bypass valve 8 is configured in the same manner as the previous example, and has an actuator 9 that is downstream of the throttle valve 6 and into which the negative intake pressure of the intake passage 11 upstream of the supercharger 5 is introduced.
It is opened and closed by. In addition, the bypass valve 8
The downstream bypass passage 12 includes a resonance chamber 13 whose volume has been expanded.
is formed, and the downstream part including this resonance chamber 13 is configured as a resonance passage section 12c, and a similar resonance chamber 14 is formed.
is formed in the intake passage 11 immediately downstream of the supercharger 5.

Further, the bypass passage 1 downstream of both resonance chambers 13 and 14
2 and the intake passage 11 are connected to each other,
A communication opening/closing valve 16 is interposed in this communication passage 15 . The communication opening/closing valve 16 is opened and closed by an actuator 17, and a three-way solenoid valve 19 is disposed in the negative pressure introduction passage 18, and the operation of the three-way solenoid valve 19 is controlled by receiving an engine rotation signal from an engine rotation sensor 20. It is controlled by a control signal from the controller 21.

The opening/closing control of the communication on-off valve 16 by the controller 21 is performed to close in a low rotational speed region of the engine;
When the engine speed increases and reaches a predetermined speed, a signal is output from the controller 21 to the three-way solenoid valve 19, and by opening the communication on-off valve 16, the natural frequencies of the resonance passage portions 12c are adjusted respectively. The system switches to obtain dynamic supercharging in synchronization with the rotation speed corresponding to the rotation range of the engine. This switching of the communication on-off valve 16 is performed at a time when the engine torque is the same between the open state and the closed state, so as to suppress the occurrence of switching shock.

As shown by the chain line in the figure, instead of or in combination with the configuration of the communication passage 15, a second on-off valve 22 is interposed at the connection 12b between the downstream end of the intake passage 11 and the bypass passage 12. In this way, the same function as the communication on-off valve 16 may be obtained, or the tuning point may be switched in more steps. This second on-off valve 22 is the communication on-off valve 16
Similarly, opening and closing are controlled according to the engine speed, and in multi-stage switching, it is sufficient to operate at a lower speed than the communication on-off valve 16. Furthermore, when opening and closing the communication valve 16 in place of the communication on-off valve 16, it is necessary to operate the valve to open for natural suction in a light load range.

゛With the above configuration, the bypass valve 8 operates in the same manner as in the previous example, and supplies intake air from the bypass passage 12 by opening in the low rotation range, and supplies air to each cylinder 1a to 1d with the supercharger 5 not creating passage resistance. Intake is performed through natural intake from both sides of the cylinder row. Furthermore, when the boost pressure becomes excessive, the bypass valve 8 opens and regulates the upper limit of the boost pressure.

The bypass passage 12 and the intake passage 11 perform dynamic supercharging at a tuned rotational speed corresponding to the resonance chamber 13, 14 and the natural frequency according to the passage length, and the communication on-off valve 16 or the second The natural frequency of the passage system changes according to the opening/closing operation of the on-off valve 22, and dynamic supercharging can be obtained over a wide range. Therefore, dynamic supercharging in a region where boost pressure is insufficient can improve engine output by increasing the charging amount, and dynamic supercharging in a region where boost pressure can be secured can improve the engine output. It is possible to reduce the supercharging pressure by the supercharger 5 by the amount of increase in the amount of filling obtained by charging, and the drive of the supercharger 5 by the engine can be reduced, thereby reducing the amount of work.

Embodiment 3 This embodiment is shown in FIG. 3, and is an example in which the difference between cylinders in dynamic supercharging using a bypass passage is reduced.

Branch intake passages 3a to 3d connected to the intake ports 2 of the cylinders 1a to 1d of the engine main body 1 are collected on the upstream side thereof and extended further upstream by a common intake passage 24. A mechanical supercharger 5 that is driven from the output shaft of the engine 1 via a transmission mechanism 25 to supercharge intake air is interposed in the middle of the intake passage 24 . Also, an intercooler 2 that cools the pressurized air by the supercharger 5
6 is interposed on the downstream side. A throttle valve 6 and an air flow meter 27 are interposed in the intake passage 24 on the upstream side of the supercharger 5.

Further, the bypass passage 28 that bypasses the supercharger 5 has an upstream end 28a connected to the intake passage 24 upstream of the supercharger 5, and a downstream end 28b connected to the intake passage 24 upstream of the supercharger 5 and for each cylinder 1a to Branch intake passage 3 connected to intake boat 2 of 1d
It is connected to the downstream side of the gathering parts a to 3d. and,
A loop-shaped passage is formed by the bypass passage 28 and the intake passage 24 downstream of the throttle valve 6, and the passage is connected from both sides to a gathering portion of the branched intake passages 3a to 3d of the cylinders 1a to 1d.

A bypass valve 8 for opening and closing the passage 28 is interposed at the opening of the upstream connecting portion 28a of the bypass passage 28. This bypass valve 8 is constructed in the same manner as the previous example, and is opened and closed by an actuator 9 to which intake negative pressure of the intake passage 24 downstream of the throttle valve 6 and upstream of the supercharger 5 is introduced. Further, a resonance chamber 29 whose volume has been expanded is formed in the bypass passage 28 downstream of the bypass valve 8, and the downstream portion including this resonance chamber 29 is configured as a resonance passage portion 28c, and a similar resonance chamber 30 is formed in the intake passage 24 downstream of the intercooler 26.

In the above connection structure between the intake passage 24 and the bypass passage 28, the equivalent in the passage from the gathering part of the branched intake passages 38 to 3d of each cylinder 1a to 1d to the resonance chambers 29 and 30 of each of the intake passage 24 and the bypass passage 28. By setting the pipe lengths to equal values, similar pressure waves act from both sides of the cylinder row, reducing the difference in dynamic supercharging between the cylinders 1a to ld. For the above equivalent pipe length, if the cross-sectional areas of the intake passage 24 and the bypass passage 28 are the same, the passage lengths up to the resonance chambers 29 and 30 of both can be set to be the same, and if the cross-sectional areas of the two are significantly different, then , (aisle volume/
What is necessary is to set the ratio of cross-sectional area) to be the same.

With the above configuration, the bypass valve 8 operates in the same manner as the previous example, and supplies intake air from the bypass passage 28 by opening in the low rotation range, and supplies each cylinder from both sides of the cylinder row with the supercharger 5 not creating passage resistance. Inhale by natural inhalation as evenly as possible from 1a to 1d. Further, when the supercharging pressure becomes excessive, the bypass valve 8 is opened to relieve the supercharging pressure and regulate its upper limit.

Further, the bypass passage 28 and the intake passage 24 perform dynamic supercharging at a tuned rotational speed corresponding to a natural frequency corresponding to the resonance chamber 29, 30 and the passage length,
By setting the synchronization point to obtain dynamic supercharging in the region where boost pressure is insufficient, engine output can be improved by increasing the charging amount, and dynamic supercharging can be achieved in the region where boost pressure can be secured. When the charge is obtained, the charging amount increases due to this dynamic supercharging, and the supercharging pressure by the supercharger 5 can be reduced by the increase in the charging amount obtained by this dynamic supercharging. The amount of work can be reduced by reducing the drive by the engine of the machine 5.

In addition, the bypass passage 28 is connected to the downstream end of the intake passage 24 to achieve dynamic supercharging and equalization of the intake air amount among the cylinders 1a to 1d in the plurality of cylinders.

In each of the above embodiments, the mechanical supercharger 5 is used as the supercharger, but the present invention is also applicable to a turbo supercharger. In addition, in Examples 2 and 3, the resonance chamber was formed in the shape of a tank with an enlarged volume of the passage. The design can be changed as appropriate to a structure in which vibrator-shaped branch passage portions are connected.

(Effects of the Invention) According to the present invention as described above, a bypass passage that bypasses the supercharger is provided, and the passage portion of the bypass passage that communicates with the bypass valve and the intake passage downstream of the supercharger can be used for practical use in the engine. Since the configuration is configured to set the natural frequency to perform dynamic supercharging in the rotation speed range, by obtaining dynamic supercharging in the tuned rotation range, and setting the natural frequency to the low rotation range,
When the supercharging effect of the turbocharger cannot be obtained sufficiently, dynamic supercharging can improve output performance by increasing the charging amount, but when set to a high rotation range, the charging amount obtained by dynamic supercharging will be increased. It is possible to reduce the drive of the supercharger by the increased amount, reduce its workload, and improve the efficiency of the engine as a whole, thereby improving fuel efficiency and making effective use of the bypass passage.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the intake structure of a supercharged engine according to the first embodiment of the present invention, FIG. 2 is a schematic diagram of the intake structure of a supercharged engine according to the second embodiment, and FIG. 3 is a diagram of the third embodiment. FIG. 1...engine, 2...intake boat,
4,11゜24...Intake passage, 5...
Supercharger, 7. 12.28... Bypass 'I
Ft, 7c, 12c, 28c...Resonance passage portion, 8...Bypass valve, 13, 14.29.
30...Resonance chamber.

Claims (1)

[Claims] (1) A supercharger that is interposed in the intake passage and supercharges the intake air, a bypass passage that communicates the upstream and downstream intake passages of the supercharger, and In the intake structure of a supercharged engine equipped with a bypass valve that opens and closes, the passage portion of the bypass passage that communicates with the intake passage downstream of the supercharger on the downstream side of the bypass valve is operated in the engine's practical rotational speed range. An intake structure for a supercharged engine, characterized in that the intake structure is set to a natural frequency that performs targeted supercharging.