JPS61182420A - Intake apparatus for engine equipped with supercharger - Google Patents

Abstract

PURPOSE:To improve output by installing a timing valve which is opened in the final period in the suction cycle into a supercharge passage formed in paral lel to a main intake passage and branching the supercharge passage on the downstream side of the timing valve into two passages and installing a shutter valve into one among the branched supercharge passages. CONSTITUTION:A vane type supercharger 19 is installed into a supercharge passage 18 which is branched from a main intake passage 13 on the downstream of an air flow meter 15 and connected to a supercharge port 7, and a cooler 21, surge tank 22, rotary timing valve 23 and a supercharge valve 24 are connected in succession. The supercharge passage 18 on the downstream of the timing valve 23 is branched into the first and the second branched passages 18a and 18b by a partitioning wall 26. A shutter valve 27 is installed into the second branched passage 18b on the side which permits the early communication in the direction of revolution of the rotary body 35 of the timing valve 23. Said shutter valve 27 is controlled to the side where the opening degree increases according to the increase of the supercharge pressure on the upstream side of the timing valve 23, by a controller 28.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an intake system for a supercharged engine that supplies pressurized air from a supercharger at the end of an intake stroke.

(Prior art) Generally, in an engine that supplies pressurized air through a supercharging passage equipped with a supercharger in addition to natural intake through the main intake passage, pressurized air from the supercharging passage is supplied to the main intake. In order to prevent backflow into the passage and interfering with natural intake through the main intake passage, a timing valve is provided in the supercharging passage to supply supercharging air only at the end of the intake stroke.

For example, as seen in Japanese Patent Application Laid-Open No. 55-137314, the gap between the timing valves is made variable depending on the engine speed, etc. to lengthen the supercharging period at high speeds and increase the charging amount. However, as in the prior art described above, providing a poppet timing valve that directly opens and closes the opening of the supercharging passage to the combustion chamber and changing the opening and closing timing requires a drive mechanism. It is complicated and has problems in terms of cost J5 and reliability.

On the other hand, as the timing valve, it is preferable to use a rotary timing valve, which opens and closes the supercharging passage at a predetermined timing by a rotary body that is rotationally driven in synchronization with engine rotation, because of its simple structure. However, since the rotary timing valve described above is configured to open the passage when the opening provided in the rotating body coincides with the downstream side of the supercharging passage due to the rotation of the rotating body, the opening/closing timing by this timing valve is It is difficult to perform variable control such as changing the valve opening timing and lengthening the valve opening period at high speeds, and keeping the boost pressure high.

Therefore, the supercharging passage on the downstream side of the rotary timing valve is branched into multiple branch passages, and a shutter valve is provided in the branch passage where the timing valve opens earlier among these branch passages. It is conceivable to switch the opening and closing of this shutter valve depending on the engine speed. In other words, at low speeds, the shutter valve is closed, and the remaining branch passages are opened by timing valves to maintain the supercharging pressure at a high level with a late valve opening period and a short valve opening period for supercharging, while at high speeds, the shutter valve is closed. When the valve is opened, all passages are opened by a timing valve, resulting in an early valve opening timing and a long valve opening period, thereby improving filling efficiency.

However, in the range where the shutter valve is switched, for example in the medium speed range, when the shutter valve is opened,
As the opening area, which had been restricted until then, suddenly expands, the supercharging pressure decreases accordingly, and even though the supercharging period becomes longer, the charging amount does not increase and sufficient supercharging effect is achieved. may not be obtained, and good output performance may not be ensured.

Although it is conceivable to open and close the shutter valve using exhaust pressure, a decrease in supercharging pressure during the switching is unavoidable.

As mentioned above, in response to an increase in engine speed, advancing the supercharging timing is a major factor in increasing output, and in this respect, opening the shutter valve all at once allows for a larger opening area and prevents overheating. This is advantageous in that the feed resistance becomes smaller, but as a result of various experiments, there was a sluggishness in the output performance due to the decrease in boost pressure in the shutter valve opening range, and when the shutter valve was opened while the boost pressure was maintained high. It has been found that providing the valve to open the valve is important in improving output performance over the entire operating range.

<Object of the Invention> In view of the above circumstances, the present invention is designed to open a shutter valve provided in a part of the supercharging passage downstream of the timing valve while maintaining the supercharging pressure at a high value. The object of the present invention is to provide an intake system for a supercharged engine that improves output performance in the switching operation range of a shutter valve.

(Structure of the Invention) The intake device of the present invention branches the supercharging passage on the downstream side of the rotary timing valve provided in the supercharging passage into a plurality of branch passages, and also connects the timing valve at the back of these branch passages. A shutter valve for opening and closing the branch passage is disposed in the branch passage on the side where the valve opens earlier, and a control device is provided for increasing the opening degree of the shutter valve in response to an increase in supercharging pressure upstream of the timing valve. When the boost pressure rises above the set pressure, the shutter valve opens, and when the boost pressure decreases with the opening of the shutter valve, the shutter valve adjusts the amount slightly and the boost pressure increases, and by repeating this, overcharging occurs. This system is characterized in that the shutter valve is gradually opened while maintaining the supply pressure.

(Effects of the Invention) According to the present invention, by opening and closing the shutter valve that makes the supercharging timing variable in accordance with the supercharging pressure,
When the shutter valve is opened in response to an increase in engine speed, it opens gradually while suppressing the drop in boost pressure, so even in this switching range of the shutter valve, high boost pressure is maintained and supercharging is achieved. By advancing the start time and lengthening the supercharging period, a sufficient supercharging effect can be obtained, and J3 can be maintained in the entire operating range of the engine to ensure good output performance. Furthermore, since a supercharging period suitable for the discharge capacity of the supercharger can be set, in addition to improving output performance, unnecessary high discharge pressure can be avoided, improving reliability and fuel efficiency of the supercharger.

Furthermore, by adopting a rotary timing valve and a shutter valve, the opening timing of the supercharging passage can be variably controlled with a simple configuration, without complicating the structure or increasing costs. The required filling m is obtained.

(Example) Hereinafter, each embodiment of the present invention will be described in detail with reference to the drawings.

Example 1 Figure 1 is a schematic configuration diagram of an engine equipped with an intake system in this example, Figure 2 is a detailed diagram of the main parts, and Figure 3 is a characteristic diagram showing boost pressure characteristics with respect to engine speed. .

In the engine E, a crankshaft 4 is rotationally driven via a connecting rod 3 by the reciprocating movement of a piston 2 within a cylinder 1, and an upper part of a combustion chamber 5 defined by a cylinder 1 and a piston 2. A main intake boat 6, a supercharging boat 7, and an exhaust port 8 are provided in the main intake boat 6, a supercharging boat 7, and an exhaust port 8, respectively.

Above main intake port 6, supercharging port 7 and exhaust port 8
These are a main intake valve 9, a DI intake valve 10, and an exhaust valve 1 whose opening and closing timings are controlled by a well-known timing cam (not shown) in synchronization with the rotation of the crankshaft 4 of the engine E.
1 are opened and closed at predetermined timings. A main intake passage 13 communicating with an air cleaner 12 is connected to the main intake port 6, and an injection valve 14 for injecting fuel is disposed in this main intake passage 13. Interposed between them, from the upstream side, are an air meter 15 for detecting the amount of intake air, and a throttle valve 16 that is opened and closed depending on the load.

The main intake port 6 is opened during the intake stroke of the engine E by the main intake valve 9, and intake air is naturally drawn into the combustion chamber 5. Further, when the exhaust port 8 is opened by the exhaust valve 11, exhaust gas generated by combustion is discharged to the outside through the exhaust passage 17.

On the other hand, the upstream end of the supercharging port 7 is air 70 - meter 1.
A supercharging passage 18 branched from the main intake passage 13 located five downstream is connected to the supercharging passage 18 . A supercharger 19 consisting of a vane type air pump that sucks in air from the main intake passage 13, pressurizes it, and then discharges it is installed in the upstream side of the supercharging passage 18. through crankshaft 4
The pressurized air is fed to the supercharging port 7. The auxiliary intake valve 10 is opened and closed in synchronization with the crankshaft 4, and is opened and closed to perform supercharging between the end of the intake stroke when the main intake port 6 is closed by the main intake valve 9 and the beginning of the compression stroke. , which closes with a predetermined delay from the main intake valve 9.

The supercharging passage 18 downstream of the supercharger 19 includes a cooler 21 (intercooler) that cools pressurized air, a surge tank 22 that accumulates pressurized air, and a transmission member 25 that is synchronously driven by the crankshaft 4. A rotary timing valve 23 and a supercharging valve 24 are installed in this order.

Furthermore, the supercharging passage 18 on the downstream side of the timing valve 23 is branched by a partition wall 26, and a shutter valve 27 is interposed in one passage.
7 is opened and closed by the operation of the actuator 29 of the control device 28. On the other hand, the opening and closing of the supercharging valve 24 is controlled in conjunction with the throttle valve 16 of the main intake passage 13. Further, one end of a relief passage 30 is connected to a surge tank 22 downstream of the supercharger 19, and the other end of this relief passage 30 is connected to the main intake passage 13 via a relief valve 31.

The fuel injection timing and injection amount by the injection valve 14 are determined by the engine control unit 32 (EC) of the control device 28.
In addition to the total intake air amount signal from the air flow meter 15, detection signals such as engine speed are inputted to this control unit 32 as necessary, and based on this, the injection interval is controlled by a control signal from U). , the injection timing is calculated and determined.

Next, as shown in FIG. 2, the timing valve 23 has a rotary body 35 that is rotatably driven in synchronization with the crankshaft 4 housed in a housing 34, and is opened at one of the central shafts of the rotary body 35. Pressurized air from the surge tank 22 is introduced into the introduction port 1-36, and when the opening 35a formed on the outer periphery matches the communication part of the passage 18 on the downstream side, the pressurized air is introduced into the combustion chamber 5 side. It is something that is discharged. The supercharging passage 18 on the downstream side of the timing valve 23 is separated by a partition wall 26 into a first branch passage 18a and a second branch passage 18b.
A shutter valve 2 that opens and closes the second branch passage 18b is provided in the second branch passage 18b on the side that communicates earlier with respect to the rotation direction of the rotating body 350 of the timing valve 23.
7 is interposed.

Further, the supercharging valve 24 is provided in the downstream supercharging passage 18.
is installed. The shutter valve 27 has a control i.
Two diaphragm type actuators of the No. 11 device 28 are connected, and the shutter valve 27 is opened and closed by introducing supercharging pressure to the actuator 29.

That is, the rotary lever 37 of the shutter valve 27
The other end of a rod 29b, one end of which is fixed, is connected to a diaphragm 29a of the actuator 29, and the diaphragm 29a is biased in the direction of closing the shutter valve 27 by a compressed spring 29c, thereby closing the pressure chamber 29d.
The shutter valve 27 is activated by the boost pressure on the upstream side of the timing valve 23 introduced by the boost pressure introduction passage 38.
The other end of the supercharging pressure introduction passage 38 is connected to the surge tank 22 and opened. Also,
A delay valve 39 is interposed in this supercharging pressure introduction passage 38 to delay the transmission of pressure.

According to the embodiment described above, depending on the operating state of the engine E, the throttle valve 16 of the main intake passage 13 and the supercharging valve 24 of the supercharging passage 18 are operated to the opening degree corresponding to the load, thereby preventing overload. The pressurized air supplied by the supply 119 is
Depending on the opening degree of the supercharging valve 24, supercharging is performed when the 01 intake valve f10 is interposed in the combustion chamber 5 at the end of the intake stroke.

This supercharging start timing, supercharging period, and supercharging pressure are controlled by opening and closing of the shutter valve 27 by the control device 28 .

In other words, the boost pressure discharged from one supercharger increases as the engine speed increases, but as shown in Figure 3, when the shutter valve 27 is open, the Since the passage area for feeding is narrow only in the first branch passage 18a, the supercharging pressure is high as shown in straight line A. On the other hand, when the shutter valve 27 is listening, both branch passages 18a and 1
Since the passage area due to 8b is large, the supercharging pressure is lower than that on straight line B (-5). When the supercharging pressure introduced into the two actuators reaches a set value Pl (engine rotation fiN+), the diaphragm 29a is displaced against the spring 29c, and the shutter valve 27 is opened. Since the shutter valve 27 is closed in the region below this set pressure P1, the increase in supercharging pressure with respect to the engine speed fluctuates along the above straight line A, and when this set pressure PL is reached, the shutter valve 27 gradually closes. It operates to open. At that time, when the boost pressure rises and the shutter valve 27 starts to open, the boost pressure changes so that the pressure decreases in the direction of straight line B according to the opening degree, and the value becomes lower than the set pressure P1. When it decreases, the shutter valve 27
The opening degree of decreases, and the boost pressure increases to open the shutter valve 27.By repeating this operation, the shutter valve 27 is gradually opened while maintaining the boost pressure at the set value P+. It operates so that it opens. When the shutter valve 27 is fully open (engine speed Nz>),
This time, the supercharging pressure increases along the straight line B, and the upper limit of the supercharging pressure is regulated by the set pressure P2 of the relief valve 31.

As the shutter valve 27 opens from the open state as described above, supercharging is started from the rotation angle at which the opening 35a of the rotating body 35 communicates with the second branch passage 18b, and the first
The supercharging period is until the communication between the branch passage 18a and the opening 35a ends.

Therefore, at high speeds when the shutter valve 27 is open, the supercharging start timing becomes earlier than at low speeds, the supercharging period becomes longer, and the charging Φ increases. In addition, even if the shutter valve 27 is in the process of gradually opening a3, the supercharging pressure is kept approximately constant, but as the engine speed increases, the opening degree of the shutter valve 27 increases, reducing the supercharging resistance. This increases the filling amount and improves output performance.

On the other hand, the delay valve 39 interposed in the supercharging pressure introduction passage 38 to the actuator 29 delays the transmission of pressure fluctuations, thereby delaying the opening/closing operation of the shutter valve 27 in response to fluctuations in supercharging pressure. Output 1
This is to ensure the feeling of deceleration during stomach and deceleration. That is, during acceleration, the opening of the shutter valve 27 is delayed, so that the boost pressure increases quickly, and during deceleration, the closing of the shutter valve 27 is delayed, which causes the boost pressure to drop quickly, increasing engine braking performance. At the same time,
The shutter valve 27 can be prevented from opening and closing due to a sudden change in engine speed during a shift change.
7 reliability is improved.

Embodiment 2 In this embodiment, the overall configuration diagram is shown in FIG. 4, and the details of the control device are shown in FIG. In contrast, the control device 41 is different, and the main intake passage 13, supercharging passage 18, timing valve 23, shutter valve 27, etc. are constructed in the same way in 1) and 4 examples, and the same structures are given the same reference numerals. The explanation will be omitted.

In the control device 41, the two actuators for opening and closing the shutter valve 27 are constructed of a diaphragm device similar to the one mentioned above, and the introduction pressure is controlled in the middle of the supercharging pressure introduction passage 42 that introduces supercharging pressure into the pressure chamber 29d. A duty solenoid valve 43 is interposed to adjust and control. A control signal from the engine control unit 32 is output to this duty solenoid valve/13, and a signal from a pressure sensor 44 for detecting boost pressure is output to the control unit 32. That is, one end of the supercharging pressure introduction passage 42 is connected to the pressure saw chamber 29d of the actuator 29, and the other end thereof is connected to the surge tank 22 upstream of the timing valve 23, and the duty solenoid valve 43 is connected to the actuator 29. As the introduced supercharging pressure increases, the opening degree of the shutter valve 27 increases, and on the other hand, when the solenoid valve 43 is closed, the pressure chamber 2
The shutter valve 27 is configured to be closed by introducing atmospheric pressure from the popular opening 42a into the opening 9d.

The above = 1 n 1 ~ roll unit 32 is the pressure sensor 4
4, and compares it with a set value to control the opening of the shutter valve 27, that is, the boost pressure, to a predetermined value. It can be changed according to E's operating status, etc., and can perform supercharging pressure control with more accurate and complex characteristics than the previous model without being affected by pulsating changes in supercharging pressure. It is.

Note that each of the above embodiments describes an example in which the supercharging passage downstream of the timing valve is branched into two to switch the supercharging period into two stages. If the fuel cell is further divided into a large number of branch passages along the same line, and shutter valves are provided to sequentially open the valves, it is possible to obtain a variable supercharging period function in roughly multiple stages.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram of a supercharged engine equipped with an intake system according to a first embodiment of the present invention, and FIG. 2 is a sectional view showing the detailed structure of a control device portion in the first embodiment. Fig. 3 is a characteristic diagram showing supercharging pressure characteristics with respect to engine speed, Fig. 4 is an overall configuration diagram of a supercharged engine equipped with an intake device according to a second embodiment of the present invention, and Fig. 5 is a characteristic diagram showing supercharging pressure characteristics with respect to engine speed. FIG. 3 is a cross-sectional view showing the detailed structure of a control device in the embodiment. E...Engine 6...Main intake boat 7...Supercharging boat 13...
...Main intake passage 18...Supercharging passage 1
......Supercharger 18a, 18b...Branch passage 22...Suji tank 23...Timing valve 27...Shi setter Valve 28, /11... Two control devices... Actuator 32... Engine control unit 35.
...Rotating body 35a...Opening 38.42...Supercharging pressure introduction passage 43...
Solenoid valve 44... Pressure sensor Figure 1

Claims (1)

[Claims] (1) In addition to the main intake passage, a supercharging passage in which a supercharger is arranged is provided upstream, and a rotary timing valve is installed in this supercharging passage to open the supercharging passage at the end of the intake stroke. In an intake system for a charged engine, the supercharging passage on the downstream side of the timing valve is branched into a plurality of branch passages, and one of the branch passages is connected to the branch passage on the side where the timing valve opens earlier. A supercharged engine, comprising a shutter valve for opening and closing a passage, and a control device for increasing the opening degree of the shutter valve in accordance with an increase in supercharging pressure upstream of the timing valve. intake device.