JPS61218719A - Intake device of engine with supercharger - Google Patents

Abstract

PURPOSE:To control an opening and closing valve to be surely actuated, by providing a long passage, corresponding to an intake pulsation in low speed operation, and a short passage, for use in high speed operation, in an intake passage and driving the valve, which opens and closes the passage for use in high speed operation, by a supercharge pressure. CONSTITUTION:An intake path 17 branches from the half way of intake pipes 12a-d, communicating with the first volume chamber 13, and communicates with the second volume chamber 14, and an engine, providing the intake path 17 in every cylinder, arranges an opening and closing valve 19, driven by an actuator 20, in a branch part of the intake path 17. The engine, providing a turbocharger 22 in the upstream of each volume chamber 13, 14 through an intake pipe 26, introduces a supercharge pressure in the first volume chamber 13 to a chamber 20a of the actuator 20 through a selector valve 35. A control unit 37, switching the selector valve 35 to a side of the atmospheric pressure when the engine is in low speed operation, closes the valve 19 by a spring. The control unit 37 switches the selector valve 35 to a side of the supercharge pressure when the engine is in high speed operation, and the engine, opening the valve 19 only when the supercharge pressure sufficiently rises, obtains an intake system corresponding to that in high speed operation.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement in an intake system for a supercharged engine that aims to improve output through the dynamic effect of intake air.

(Prior art) Conventionally, in the intake system of an engine equipped with a supercharger,
By utilizing the fact that the pressure waves that occur with the start of intake are reflected at the open end of the intake passageway to the atmosphere or the volume chamber and returned toward the intake boat, the reflected waves generate the intake air just before the intake valve closes. so that it reaches the boat and increases the intake pressure,
Some devices are designed to increase the filling efficiency of intake air using the so-called inertia effect of intake air. When trying to use power improvement technology that utilizes the dynamic effects of intake air, if the intake path is constant, the oscillation cycle of the pressure waves generated in the intake passage and the intake valve opening/closing cycle will not match, resulting in inertia. The effect is only enhanced in a specific speed range.

For this reason, as seen in Japanese Patent Application Laid-Open No. 58-105626, the length of the intake passage is changed depending on the rotation speed of the supercharged engine. A long passage and a short passage are formed by branching, and the upstream ends of these passages are opened to the intake volume, etc., and an on-off valve is provided in the short passage, and by opening this on-off valve in the high speed range, the intake passage is to shorten the effective length of
In this way, an intake device has also been proposed in which the inertia effect of intake air is increased in both the low speed range and the high speed range.

In order to obtain the dynamic effect of intake air over a wide range as described above, it is necessary to provide an actuator for the on-off valve that selects the intake path depending on the engine speed. Some of these actuators use electromagnetic actuators as in the previous example, but they have the problem of high cost (and increased power consumption).Also, pressure actuators that use intake negative pressure are used. However, due to the arrangement of the turbocharger, the area where intake negative pressure is generated is narrow, and a large vacuum chamber that accumulates this intake negative pressure and a high sealing performance to maintain the negative pressure are required. This is necessary, and there are problems with stability, especially when operation continues in the high load range.

(Object of the Invention) In view of the above circumstances, the present invention utilizes the dynamic effect of intake air to increase the intake air filling efficiency from low speed range to high speed range, and also provides an on-off valve for expanding the above dynamic effect. It is an object of the present invention to provide an intake system for a supercharged engine that provides reliable operation.

(Structure of the Invention) The intake device of the present invention is provided with an on-off valve that selects a plurality of routes according to the engine speed, in order to match the dynamic effect of intake air in response to changes in the engine speed. A pressure actuator that connects a drive means for driving the on-off valve to the on-off valve, a supercharging pressure introduction passage that communicates a pressure chamber of the pressure actuator with an intake passage on the downstream side of the supercharger, and a supercharging pressure introduction passage in the pressure chamber. The present invention is characterized by comprising a control means for controlling the pressure according to the engine speed.

(Effects of the Invention) According to the present invention, the dynamic effect of intake air is effectively utilized over a wide range of engine speeds through the operation of the on-off valve, and high charging efficiency is obtained from low speed ranges to high speed ranges, resulting in improved output performance. This is something that can be improved.

In addition, by connecting the boost pressure introduction passage that introduces boost pressure to the pressure actuator that operates the on-off valve, and using this boost pressure to open and close the on-off valve, there is no need for a vacuum chamber, etc. Therefore, the drive means for the on-off valve can be configured at low cost without increasing power consumption.

In particular, the above-mentioned on-off valve is required to operate in a high load range, and at this time the boost pressure is sufficiently increased to ensure that the on-off valve remains open or closed. This is extremely useful in practice, as the reliability of operation is improved, and the fluctuation characteristics of the supercharging pressure match the requirements for the opening and closing characteristics of the on-off valve, making it easy to achieve desired control.

(Example) Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a sectional front view of an engine equipped with an intake system of this embodiment, and FIG. 2 is a schematic plan view.

The engine of this embodiment is a four-cylinder four-cycle engine, and an engine body 1 consisting of a cylinder block 2 and a cylinder head 3 has four cylinders 4a to 4d formed therein. A combustion chamber 6 is formed above the piston 5 in each of the cylinders 4a to 4d, and an intake port 7 and an air intake boat 8 are opened in the combustion chamber 6.
．． 8 is equipped with an intake valve 9 and an exhaust valve 10 which are opened and closed at predetermined timing by a valve operating mechanism 11.

The intake ports 7 of the cylinders 4a to 4d communicate with independent intake passages 128 to 12d for each cylinder, which are independent from each other. The upstream ends of these independent intake passages 128 to 12d are connected to the first volume chamber 13 having a certain capacity, and these independent intake passages 128 to 12d are connected to the middle of each of the independent intake passages 12a to 12d. A second volume chamber 14 is connected to communicate the two volumes 12d with each other. by this,
Long and short 2 in communicating each cylinder 4a to 4d and volume chamber 13.14
It forms two intake paths.

In this embodiment, in order to configure the intake system compactly, a tank 15 installed in the intake system is divided by a partition wall 16, thereby dividing the tank 15 into a first volume space 13 and a second volume chamber 14. A branched communication hole 17 is opened at the lower end of the second volume chamber 14 from a midway point of each independent intake passage 12a to 12d, and each independent intake passage 12a to 12d is opened on the upstream side of the communication hole 17. It is curved so that its upstream end opens to the side of the first volume chamber 13 . The upstream curved portions of each of the independent intake passages 128 to 12d are integrally formed using the wall of the second volume chamber 14 of the tank 15.

An on-off valve 19 is provided in each communication hole 17 between the second volume chamber 14 and each of the independent intake passages 12a to 12d. Each on-off valve 19 is integrally connected to a rotating shaft 19a, and a drive means 2 is attached to an end of the rotating shaft 19a.
1 pressure actuator 20 (not shown in Figure 2)
are connected and each cylinder is opened and closed in conjunction with each other.

Basically, the on-off valve 19 is controlled to be closed in a low speed range where the engine speed is less than a set value in a high load range, and opened in a high speed range where the engine speed is equal to or higher than the set value.

Further, an upstream intake air introduction passage 26 is connected to one end of the first volume chamber 13, and a throttle valve 27 is disposed in this intake air introduction passage 26, and the upstream end thereof is connected to a turbo supercharger 22. It is connected to the floor 22a, and connected to an air cleaner via an air flow meter (not shown) or the like. An exhaust manifold 23 that communicates with the exhaust boat 8 is connected to the turbine 22b of the turbocharger 22, and a blower 22a is driven to rotate by introducing exhaust gas through a turbine 22t). Further, a fuel passage 2 is provided near the downstream end of each of the independent intake passages 12a to 12d.
A fuel injection valve 29 connected to 8 is provided.

The pressure actuator 20 in the driving means 21 is provided in a diaphragm type using the supercharging pressure of the first volume chamber 13 as an operating source, and opens the on-off valve 19 by introducing the supercharging pressure. The other end of the supercharging pressure introduction passage 30, one end of which is connected to the pressure chamber 20a of this pressure type actuator 20, is communicated with the first volume chamber 13, and is opened and closed by a spring 20b that is compressed in this pressure type actuator 20. Valve 19 is operated in the closed state. Further, a three-way solenoid valve 35 is interposed in the boost pressure introduction passage 30,
It operates by switching between introducing supercharging pressure into the pressure actuator 20 and opening it to the atmosphere. A control signal from a control means 37 (engine control unit) is output to this three-way solenoid pulp 35, and its operation is performed according to the engine rotation speed to control the pressure within the pressure chamber 2Oa. The control means 37 receives an input of the amount detected by the rotational speed sensor 38 of the engine rotational speed.

The opening operation of the on-off valve 19 by the drive means 21 is carried out in the region where the engine speed is equal to or higher than a set value, and when this set value is reached, a control signal is sent from the control means 37 to the three-way solenoid 35. The intake pressure (supercharging pressure) of the first volume chamber 13 is outputted and introduced into the pressure chamber 20a of the pressure actuator 20. When the supercharging pressure introduced into the pressure chamber 20a is lower than the set value defined by the spring 20b, the pressure actuator 20 uses the biasing force of the spring 20b to open/close the valve 19.
This is provided in the normally closed type to keep the
The configuration is such that the +1 valve 19 begins to open and gradually opens as the supercharging pressure increases.

In the device of the above embodiment, when the engine speed is in a low speed range below the set value, the pressure actuator 20
The pressure chamber 20a is open to the atmosphere and the on-off valve 19 is closed, and each independent intake passage 12a to 12d and the second volume chamber 14
Because communication with Taki 11!4a-4d has been cut off,
is connected to the first volume chamber 13 via a relatively long passage spanning the entire length of each independent intake passage 12a to 12d.

Therefore, the pressure waves generated during the intake stroke of each cylinder 4a to 4d pass through each independent intake passage 12a to 12d to the first volume space 13.
is propagated to the first volume chamber 13 and reflected to each cylinder 4a to 4d, causing intake pressure vibration in each independent intake passage 12a to 12d. Therefore, each cylinder 4a to 4d and the first volume v1
In the low speed rotation range where the period of natural vibration of the intake system occurring in the independent intake passages 12a to 12d between the cylinders 3 and 3 matches the intake valve opening/closing period, the pressure acting on each cylinder 4a to 4d is It is increased at the end of the stroke, improving filling efficiency.

On the other hand, when the engine speed is in a high speed range equal to or higher than the set value and the boost pressure introduced into the pressure chamber 20a increases and the on-off valve 19 is open, each independent intake passage 12a to 12d
and the second volume chamber 14 are communicated with each other through the communication hole 17, and each cylinder 4a to 4d communicates with the second volume chamber 14 through a relatively short passage length of each independent intake passage 12a to 12d. Connected to sky 14. At this time, intake air is supplied from the first volume chamber 13 through the independent intake passages 12a to 12d, and also to the independent intake passages 12a to 12d of the other cylinders.
The air is supplied from the second volume chamber 14 communicating therewith by its independent intake passages 128 to 12d.

In this state, the pressure waves generated during the intake stroke are reflected by the second volume chamber 14, and the length of the passage through which the pressure waves and reflected waves propagate becomes shorter, thereby reducing the intake inertia effect in the high-speed range. At the same time, in this operating range, pressure waves propagated from other cylinders also act effectively, improving charging efficiency.

FIG. 3 shows the open area I of the on-off valve 19 in relation to the engine speed and torque. Curve A is the fully open line when the on-off valve 19 is closed, and curve B is the full open line when the on-off valve 19 is closed. This is the fully open line in the open state, and the engine rotation speed NO corresponding to the point where the double convex lines A and B intersect is the set value No that operates the three-way solenoid valve 35 to open and close the on-off valve 19. , which closes at lower speeds and opens at open region (2) in the high load range at higher speeds, and aims to improve output by increasing intake air filling efficiency over the entire rotation range.

The change characteristics of the intake pressure (supercharging pressure acting on the pressure chamber 20a) along the operating line E where the throttle opening is increased to increase the torque (load) when the engine speed is constant as shown in Fig. 3. It is shown in FIG. 4A. In FIG. 4A, in response to an increase in boost pressure, the on-off valve 19 starts to open when the boost pressure is at the first set pressure P1, and when the boost pressure is at the second set pressure P2, the on-off valve 19 starts to open.
The spring 20b is set so that the spring 9 is fully open.

Correspondingly, the on-off valve 19 gradually opens while the supercharging pressure changes from the first set pressure P1 to the second set pressure P2 as shown in FIG. 4B. According to the above operation, the torque change with respect to the throttle operation along the operation line E becomes as shown in FIG. 4C. That is, with respect to an increase in the throttle opening at a constant rotation speed, curve A' is the torque curve when the on-off valve 19 is closed, curve B' is the torque curve when the on-off valve 19 is open; The torque increases due to the operation, but during this change in throttle opening, the on-off valve 79
is gradually opened from point a to point b, so the torque performance changes so that the torque gradually increases from curve A to curve B, and the opening/closing valve 19 is opened and closed without sudden torque shock. That's what I do.

In the above embodiment, an example was shown in which the on-off valve 19 was configured as a normally closed type that opens only in the area of work shown in FIG. In the load range, the change in charging efficiency due to opening and closing is substantially absorbed in relation to the throttle operation, so conversely, in the high load range below the set value No of the engine speed in Fig. 3A. It may be provided in a normal oven type in which the on-off valve 19 is closed only in the closed region (2). In this case, the opening/closing valve 19 is operated to gradually close in response to an increase in boost pressure in response to an increase in throttle opening at a constant rotation speed.

Further, although the above embodiment shows an example of a turbo supercharger, other superchargers can also be used, and supercharging by a supercharger and natural intake may be used for VT. It is.

Furthermore, as a plurality of intake passages to obtain a dynamic effect of intake air, in addition to the one in which the length of the intake passage is changed and the communication with the intake passage of other cylinders is switched as in the above embodiment, It is possible to adopt a plurality of intake paths by changing various dynamic effects such as changing the area of the intake passage or changing the volume of the intake volume chamber, or by combining these structures, and these can be opened and closed according to the engine speed. The configuration is such that supercharging pressure is introduced into the drive means of the selected on-off valve to operate it as described above. Further, the upstream end of the intake path for obtaining the dynamic effect of intake air communicates with the intake volume chamber or the atmospheric opening.

[Brief explanation of the drawing]

Fig. 1 is a sectional front view of an engine equipped with an intake system according to an embodiment of the present invention, Fig. 2 is a schematic plan view thereof, and Fig. 3 is an opening/closing region of an on-off valve based on torque characteristics according to engine speed. Figure 4A, 8.0 is a characteristic diagram showing the intake pressure change, the opening/closing state of the "open" valve, and the torque fluctuation, respectively, along the operating line when the throttle opening is increased at a constant rotation speed. . 1...Engine body 4a-4d...
...Cylinder 12a to 12d...Independent intake passage 13
......First volume chamber 14...Second volume chamber 19...Opening/closing valve 21...
・Driving means 20...Pressure actuator 20
a...Pressure chamber 20b...Spring 22...Turbo supercharger 30...Supercharging pressure introduction passage 35...3-way solenoid Pulp 37...
・Control means

Claims (1)

[Claims] (1) Supercharging that is equipped with a turbocharger, has multiple intake paths that communicate between one cylinder and the intake volume chamber or atmospheric opening, and is equipped with an on-off valve that selects these multiple paths depending on the engine speed. In an intake system for an engine equipped with a motor, a driving means for driving the on-off valve is connected to a pressure actuator connected to the on-off valve, and a supercharging system that communicates a pressure chamber of the pressure actuator with an intake passage on the downstream side of a supercharger. An intake system for a supercharged engine, comprising a pressure introduction passage and a control means for controlling the pressure in the pressure chamber according to the engine speed.