JP2784775B2 - Intake structure of supercharged engine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to an intake structure in a supercharged engine having a supercharger.

(Prior Art) Conventionally, as disclosed in, for example, Japanese Patent Application Laid-Open No. 62-87615, a supercharger is provided in an intake passage of an engine, and the supercharger is operated to supercharge intake air. A supercharged engine in which the output torque of the engine is increased by increasing the intake charge amount to the cylinder is widely and generally known.

Further, in the above-described prior art, a bypass passage communicating the intake passage upstream and downstream of the turbocharger is provided, and a bypass valve that opens and closes in accordance with an operating state of the engine is provided in the bypass passage. In the bypass passage, for example, the supercharging pressure of the supercharger is low and sufficient intake cannot be secured in the low engine speed region, and the driving of the supercharger causes an output loss. Stop the operation of the feeder and open the bypass valve to supply the intake air by natural suction from the bypass passage, or open the bypass valve when the supercharging pressure rises to a set value or more, and perform supercharging. Techniques used to relieve pressure and regulate its upper limit are known.

(Problems to be Solved by the Invention) However, in the engine with a supercharger having the supercharger and the bypass passage as described above, when the engine is in a low load state or a low rotation state, the operation of the supercharger is performed. Is stopped or the supercharging pressure is low, the natural suction effect of the bypass passage alone cannot secure a sufficient filling amount for the output performance at the time of supercharging, or if the supercharging is performed under high load conditions. There is a possibility that the output loss of the engine increases due to the driving of the machine, and the efficiency as a whole decreases.

Therefore, in view of the above circumstances, the present invention utilizes a configuration of a bypass passage to obtain a dynamic effect of intake air, thereby increasing a filling amount or reducing a work amount of a supercharger. It is an object of the present invention to provide an intake structure of an engine with an engine.

(Means for Solving the Problems) In order to achieve the above object, an intake structure of a supercharged engine according to the present invention is a mechanical type that is interposed in an intake passage and driven by the engine according to an operation state to supercharge intake air. A supercharger,
A bypass passage communicating the intake passage upstream and downstream of the turbocharger; and a bypass valve opening and closing the bypass passage in accordance with an engine operating state. A passage portion communicating with an intake passage downstream of the supercharger is set to a natural frequency at which dynamic supercharging is performed at least in a low rotation region of an engine in which the operation of the supercharger is stopped. .

Further, the natural frequency of a passage portion communicating with the intake passage downstream of the supercharger on the downstream side of the bypass valve in the bypass passage is variably provided, so that dynamic supercharging is performed even in the rotation region of the engine operating the supercharger. A supply may be provided.

(Operation) In the intake structure as described above, the bypass valve in the bypass passage that bypasses the mechanical supercharger that is driven and controlled according to the operation state of the engine and the passage portion that communicates with the intake passage downstream of the supercharger are provided. It is set at a natural frequency at which dynamic supercharging is performed at least in a low rotation region of the engine in which the operation of the supercharger is stopped, and in a low rotation region where the supercharging effect of the supercharger is not obtained. An increase in the filling amount due to dynamic supercharging is obtained.

Further, if the natural frequency for performing the dynamic supercharging is variably provided so as to perform the dynamic supercharging even in the rotation region where the supercharger is operating, the increase in the filling amount obtained by the dynamic supercharging can be obtained. Only the drive of the turbocharger is reduced to reduce the amount of work and improve the efficiency.

(Embodiments) Each embodiment of the present invention will be described below with reference to the drawings.

Embodiment 1 FIG. 1 shows an embodiment of a basic configuration.

The engine body 1 has a plurality of cylinders 1a to 1d.
The branch intake passages 3a to 3d connected to the intake ports 2 to 1d are gathered on the upstream side and extended further upstream by the common intake passage 4. A mechanical supercharger 5 for performing supercharging of intake air is interposed in the intake passage 4. 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 or the like (not shown) so that the driving is stopped in the low rotation state of the engine. A throttle valve 6 is interposed in the intake passage 4 on the upstream side by the supercharger 5. Also,
An upstream end 7a is formed in the intake passage 4 on the upstream side and the downstream side of the supercharger 5.
And a downstream end 7a, and a bypass passage 7 that bypasses the supercharger 5 is provided. The bypass passage 7
In the vicinity of the upstream connection portion 7a of the supercharger 5, a bypass valve 8 for opening and closing the passage 7 is interposed. The bypass valve 8 is installed such that a valve 8a for opening and closing the passage receives in the opening direction the pressure of the intake passage 4 downstream of the supercharger 5 downstream of the bypass passage 7, and the valve 8a is provided with a diaphragm type actuator 9 Opening and closing operation supported by. The actuator 9 is provided with a spring 9a for urging the valve 8a in the closing direction. Is introduced by the negative pressure passage 9a so as to operate in the opening direction.

On the other hand, the bypass passage 7 is provided with the bypass valve 8.
The length and diameter (cross-sectional area) of the resonance passage portion 7c communicating with the intake passage 4 downstream of the supercharger 5 are tuned in the low-speed region of the engine at the downstream portion partitioned by It is set to get a dynamic supercharge. The tuning rotation speed is set in a low rotation region where the driving of the supercharger 5 is stopped.

When the tuning speed is set in the low rotation region, in this state, it is time to open the bypass valve 8 and introduce intake air from the bypass passage 7 by natural suction. When the opening operation is performed to the opening degree, the resonance passage portion 7c is opened, and the function as a resonance portion for obtaining dynamic supercharging is reduced. Therefore, the opening degree of the bypass valve 8 is set to an extent that intake air can be supplied. In this case, the resonance passage portion 7c downstream of the bypass valve 8 is configured as a volume for substantially obtaining dynamic supercharging.

Explaining the operation of this example, in a normal operating state, the supercharger 5 is driven by the driving force of the engine 1 and the intake air is supercharged and supplied to each of the cylinders 1a to 1d. Get output. When the supercharging pressure becomes excessive, the bypass valve 8 is opened to relieve the supercharging pressure and regulate the upper limit.

In the low rotation state, the rotation speed of the supercharger 5 decreases, the supercharging pressure decreases, and the driving loss increases.
Is stopped, and the large intake negative pressure of each of the cylinders 1a to 1d acts on the upstream intake passage 4 via the supercharger 5 to increase the intake negative pressure, and this negative pressure is reduced by the introduction passage 9b. As a result, the valve body 8a of the bypass valve 8 is introduced into the actuator 9 to open, and intake air is supplied from the bypass passage 7 that bypasses the supercharger 5, and each of the cylinders 1a to 1a to 1c is in a state where the supercharger 5 does not become a passage resistance. Inhale by natural inhalation in 1d.

Further, since the natural frequency of the resonance passage portion 7c of the bypass passage 7 is set to be tuned in the low rotation region as described above, the filling amount due to the dynamic supercharging of the intake air at the tuning point is reduced. The output performance is improved.

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

The branch intake passages 3a to 3d connected to the intake ports 2 of the cylinders 1a to 1d of the engine body 1 are gathered on the upstream side and further extended to the upstream side by a common intake passage 11. A mechanical supercharger 5 for supercharging the intake air is provided in the middle of the intake passage 11 as in the previous example. A throttle valve 6 is interposed in the intake passage 11 on the upstream side of the supercharger 5.

Also, a bypass passage 12 for bypassing the supercharger 5 is provided.
The upstream end 12a is connected to the intake passage 11 upstream of the supercharger 5, while the downstream end 12b is located downstream of the supercharger 5 and in each of the cylinders 1a to 1d.
Is connected to the downstream side of the gathering portion of the branch intake passages 3a to 3d connected to the intake port 2.

In the vicinity of the upstream connection portion 12a of the supercharger 5 in the bypass passage 12, a bypass valve 8 for opening and closing the passage 12 is provided. The bypass valve 8 is configured in the same manner as in the previous example, and is opened and closed by an actuator 9 into which the intake negative pressure of the intake passage 11 downstream of the throttle valve 6 and upstream of the supercharger 5 is introduced. A resonance chamber 13 having an increased volume is formed in the bypass passage 12 downstream of the bypass valve 8.
A downstream portion including the resonance chamber 13 is formed as a resonance passage portion 12c, and a similar resonance chamber 14 is formed in the intake passage 11 immediately downstream of the supercharger 5.

Further, a communication passage 15 that connects the bypass passage 12 downstream of the resonance chambers 13 and 14 and the intake passage 11 is connected, and a communication opening / closing valve 16 is interposed in the communication passage 15. The communication on-off valve 16
The three-way solenoid valve 19 is disposed in a negative pressure introducing passage 18 in an opening / closing operation by an actuator 17. The operation of the three-way solenoid valve 19 is controlled by an engine rotation sensor 20.
Is controlled by a control signal from the controller 21 having received the engine rotation signal.

The opening and closing control of the communication opening and closing valve 16 by the controller 21 is closed in the low engine speed region.
When the engine speed rises and reaches a predetermined speed, a signal is output from the controller 21 to the three-way solenoid valve 19 and the communication opening / closing valve 16 is opened, whereby the natural frequency of the resonance passage portion 12c is increased. Is switched so as to obtain a dynamic supercharging in synchronization with the number of rotations corresponding to the rotation range. The 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 the switching shock.

As shown by a chain line in the figure, a second opening / closing valve 22 is interposed at a connection portion 12b between the downstream end of the intake passage 11 and the bypass passage 12 instead of or in combination with the configuration of the communication passage 15. In this way, a function similar to that of the communication on-off valve 16 may be obtained, or the tuning point may be switched in multiple stages.
The second on-off valve 22 is controlled to open and close according to the engine speed, similarly to the communication on-off valve 16, and it is only necessary to operate at the rotation speed from the communication on-off valve 16 in multi-stage switching. Further, when opening and closing in place of the communication on-off valve 16, it is necessary to open the valve for natural suction in a light load range.

With the above-described configuration, the bypass valve 8 operates in the same manner as in the previous example, and supplies the intake air from the bypass passage 12 by the opening operation in the low rotation speed range, and the supercharger 5 operates in a state where the passage resistance does not cause the passage of each cylinder 1a.
In 1d, intake by natural suction is performed from both sides of the cylinder row. Further, when the supercharging pressure becomes excessive, the bypass valve 8 is opened to regulate the upper limit of the supercharging pressure.

The bypass passage 12 and the intake passage 11 are connected to the resonance chamber 1
Dynamic supercharging is performed at the synchronized rotation speed corresponding to the natural frequency corresponding to the passage length, and the communication on-off valve
Alternatively, it is possible to obtain a dynamic supercharging in a wide range including at least a low turning point region where the natural frequency of the passage system changes according to the opening / closing operation of the second on-off valve 22 and the operation of the supercharger 5 is stopped. Can be. Therefore, in the dynamic supercharging in the region where the supercharging pressure is insufficient, the engine output can be improved by increasing the filling amount, and in the dynamic supercharging in the region where the supercharging pressure can be secured,
The supercharging pressure by the supercharger 5 can be reduced by the increase in the filling amount obtained by the dynamic supercharging, and the driving of the supercharger 5 by the engine can be reduced to reduce the work amount.

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

The branch intake passages 3a to 3d connected to the intake ports 2 of the cylinders 1a to 1d of the engine body 1 are gathered on the upstream side and further extended to the upstream side by a common intake passage 24. A mechanical supercharger 5 driven by an output shaft of the engine 1 via a transmission mechanism 25 to supercharge the intake air is provided in the middle of the intake passage 24. Further, an intercooler 26 for cooling the pressurized air by the supercharger 5 is provided downstream. A throttle valve 6 and an air flow meter 27 are interposed in an intake passage 24 upstream of the supercharger 5.

Further, a bypass passage 28 for bypassing the supercharger 5 is provided.
The upstream end 28a is connected to the intake passage 24 upstream of the supercharger 5, while the downstream end 28b is located downstream of the supercharger 5 and in each of the cylinders 1a to 1
It is connected to the downstream side of the junction of the branch intake passages 3a to 3d connected to the intake port 2 of d. A loop-shaped passage is formed by the bypass passage 28 and the intake passage 24 downstream of the throttle valve 6, and the passages are connected from both sides to a set of branch intake passages 3a to 3d of the cylinders 1a to 1d. I have.

A bypass valve 8 that opens and closes the passage 28 is interposed in an opening of the upstream connection portion 28a of the bypass passage 28. This bypass valve 8 is configured in the same manner as the previous example,
The opening and closing operation is performed by an actuator 9 into which the intake negative pressure in the intake passage 24 downstream of the throttle valve 6 and upstream of the supercharger 5 is introduced. The bypass passage 28 downstream of the bypass valve 8 is provided with a resonance chamber 29 having an increased volume. A downstream portion including the resonance chamber 29 is formed as a resonance passage portion 28c. Is formed in the intake passage 24 downstream of the intercooler 26, and its tuning speed is set in a low rotation region where the operation of the supercharger 5 is stopped.

In the connection structure between the intake passage 24 and the bypass passage 28, the respective resonance chambers 2 of the intake passage 24 and the bypass passage 28 extend from the aggregate of the branch intake passages 3a to 3d of the cylinders 1a to 1d.
If the equivalent chiefs in the passages up to 9,30 are set to the same value, similar pressure waves will act from both sides of the cylinder row and cylinders 1a to 1d
The gap between the dynamic supercharges is reduced. The equivalent length may be set so that the passage lengths up to the resonance chambers 29 and 30 of the intake passage 24 and the bypass passage 28 are the same if the passage cross-sectional areas are the same. , (Passage volume / cross-sectional area) may be set to be the same.

With the above-described configuration, the bypass valve 8 operates in the same manner as in the previous example, supplies the intake air from the bypass passage 28 by the opening operation in the low rotation range, and sets the cylinders from both sides of the cylinder row in a state where the supercharger 5 does not become the passage resistance. Intake by natural inhalation is performed as evenly as possible in 1a to 1d. When the supercharging pressure becomes excessive, the bypass valve 8 is opened to relieve the supercharging pressure and regulate the upper limit.

Further, the bypass passage 28 and the intake passage 24 perform dynamic supercharging at a tuned rotation speed in a low rotation region corresponding to a resonance frequency corresponding to the resonance chambers 29 and 30 and a passage length. By obtaining dynamic supercharging in a region where the operation of the feeder 5 is stopped, the engine output can be improved by increasing the filling amount.

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

Although the resonance chambers of the second and third embodiments are formed in a tank shape in which the volume of the passage is enlarged, the resonance chamber in which the chamber formed in the chamber is connected to the passage or the end is closed. The design can be appropriately changed to a structure such as a structure in which pipe-shaped branch passage portions are connected.

(Effects of the Invention) According to the present invention as described above, a bypass passage that bypasses a mechanical supercharger is provided, and a passage portion that communicates with a bypass valve of the bypass passage and an intake passage downstream of the supercharger is provided. At least the natural frequency at which dynamic supercharging is performed in the low rotation region of the engine in which the operation of the supercharger is stopped is set. When the supercharging effect of the machine cannot be obtained, the output performance can be improved by increasing the filling amount due to dynamic supercharging, and the bypass passage can be effectively used.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an intake structure of a supercharged engine according to a first embodiment of the present invention, FIG. 2 is a schematic configuration diagram according to a second embodiment, and FIG. 3 is a third embodiment. FIG. 1 ... engine, 2 ... intake port, 4, 11, 24 ... intake passage, 5 ... turbocharger, 7, 12, 28 ... bypass passage, 7c, 12
c, 28c: Resonance passage, 8: Bypass valve, 13, 1
4,29,30 ... Resonance room.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Eiji Fujimoto 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Inside Mazda Corporation (56) References JP-A-61-89928 (JP, A) -224927 (JP, A) Fully open 60-6057740 (JP, U) Fully open 57-7722 (JP, U) Fully open 61-178031 (JP, U) (58) Field surveyed (Int.Cl) . ^6, DB name) F02B 33/00 - 39/16 F02B 27/00 - 27/02

Claims (2)

(57) [Claims] A mechanical supercharger interposed in an intake passage and driven by an engine according to an operation state to supercharge intake air;
In a suction structure of an engine with a supercharger, comprising: a bypass passage communicating between an intake upstream side and a downstream intake passage of the supercharger; and a bypass valve that opens and closes the bypass passage according to an engine operating state. The passage portion communicating with the intake passage downstream of the supercharger on the downstream side of the bypass valve in the bypass passage has a natural frequency at which dynamic supercharging is performed at least in a low rotation region of the engine in which the operation of the supercharger is stopped. The intake structure of a supercharged engine characterized by the setting. 2. The engine according to claim 1, wherein the natural frequency of a passage portion of the bypass passage downstream of the bypass valve and communicating with an intake passage downstream of the supercharger is variably provided, even in a rotation region of an engine operating the supercharger. The intake structure of a supercharged engine according to claim 1, wherein dynamic supercharging is performed.