JPS60228725A - Intake device of engine with supercharger - Google Patents

Abstract

PURPOSE:To improve a supercharge effect in an engine at its high speed, by connecting the downstream of a supercharger with a main intake passage through an opening and closing valve and a timing valve, in the case of the engine in which the main intake passage and a subintake passage, having the supercharger, communicate with a cylinder through each intake valve. CONSTITUTION:Air from an intake pipe 11 is introduced into a cylinder through a main intake passage 12, having a throttle valve 17, and a subintake passage 13, having a supercharger 20, control valve 22 and a timing valve 26, from intake vales 7, 8 in each intake passage. The downstream of the supercharger in the subintake passage 13 communicates with the main intake passage 12 through a control valve 28 and a timing valve 29, and a sufficient supercharge is performed in an engine at its high speed running by opening the control valve by the supercharge pressure and actuating the timing valve 29 opened and closed so as to provide the timing that supercharge air from a communication passage 27 reaches the valve 7 in the end of an intake stroke.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an engine intake system in which a supercharging passage provided with a supercharger is formed separately from a main intake passage.

(Prior art) Conventionally, as shown in Japanese Patent Publication No. 58-51134, a supercharging passage leading to the turbocharger is formed separately from the main intake passage, and the main intake port is located at the downstream end of each passage. By opening individual supercharging ports into the combustion chambers of the cylinders, supercharging air is supplied from the supercharging passage to the combustion chamber in addition to natural intake air from the main intake passage, increasing charging efficiency and increasing output. Intake devices with improved performance are known. For example, a vane type pump driven by the engine is used for the supercharger, and the higher the engine speed, the higher the displacement per unit time.
is increasing.

By the way, in such a device, as the discharge amount from the supercharger increases and the supercharging pressure increases, the flow resistance of the supercharging passage increases. There is a limit, and if the discharge amount from the supercharger increases beyond this limit, it will be relieved upstream of the supercharger by the relief passage, but at high speeds and high loads, etc., the overload to the engine will increase. It may be desirable to further increase the supply air supply. Additionally, in order to achieve effective supercharging, it is necessary to prevent supercharged air from blowing back into the main intake passage as much as possible, and for this reason conventionally a timing valve has been installed downstream of the supercharger. Therefore, supercharging is performed at the end of the intake stroke, but it is desirable to actively prevent blowback during the period from the start of supply of supercharging air until the main intake boat is closed.

(Purpose of the Invention) In view of these circumstances, the present invention has been developed to enhance the supercharging effect when the pressure in the supercharging passage becomes high, and to more reliably improve the blowback of supercharged air to the main intake passage. The present invention provides an intake system for a supercharged engine that can perform the following steps.

(Structure of the Invention) The present invention provides a system for connecting the supercharging passage of F flow from the supercharger to the main intake passage in an engine having a main intake passage and a supercharging passage including a supercharger. A passage is formed, and this communication passage is provided with a pressure valve that opens when the boost pressure exceeds a predetermined value, and a timing valve that opens and closes in synchronization with the engine. At the end of the intake stroke, the compressed air sent to the passage is sent to the cylinder in the main intake passage.
It is set so that it reaches near the tlO portion.

In other words, in the operating range where the supercharging pressure in the supercharging passage becomes high and the flow resistance in the supercharging passage becomes large, part of the supercharging air is sent into the opening of the main intake passage to the cylinder at the end of the intake stroke. At lυ,
This is designed to increase the intake pressure.

(Example) FIG. 1 shows an example of the present invention. In this figure, reference numeral 1 denotes a cylinder of an engine, in which a piston 2 is housed, and a combustion chamber 3 is formed above the piston 2. This combustion chamber 3 has a main intake port 4, a supercharging boat 5, and an exhaust boat 6, and these boats 4 to 6 are equipped with a main intake valve 7, a supercharging intake valve 8, and an exhaust valve 9, respectively. There is.

11 is an intake passage, and from the middle there is a main intake passage 1.
The main intake passage 12 communicates with the main intake port 4, and the supercharging passage 13 communicates with the supercharging bow 1-5. In the intake passage 11 upstream from the branch point between the main intake passage 12 and the supercharging passage 13, an accreech 14 and an air flow meter 15 are arranged;
According to the amount of intake air detected by the air 70-meter 15, the amount of fuel injected from a fuel injection valve (not shown) provided in the main intake passage 12 or the like is controlled.

In the main intake passage 12, there is a throttle valve 17 that is opened and closed by the throttle operation, and a surge tank 1B is formed downstream of the throttle valve 17.

Further, a supercharger 20 consisting of a vane type positive displacement pump is provided in the middle of the supercharging passage 13.
is connected to the output shaft 21 of the engine via a transmission mechanism (not shown), and is driven by the engine. A supercharging air control valve 22 is provided in the supercharging passage 13 on the downstream side of the supercharger 20 to control the amount of supercharging according to the load of the engine. Furthermore, if the engine speed increases to a certain extent without the supercharge control valve 22 being fully opened, excessive supercharge air may be discharged from the supercharger 20. A relief passage 23 for relieving excess supercharging air is formed between the downstream side and the upstream side of the machine 20, and a relief valve 24 is provided in the middle of this relief passage 23. The relief valve 24 includes a valve body 24b urged in the valve closing direction by a spring 24a, and is closed when the pressure downstream of the supercharger 820 exceeds the pressure set by the spring 24a. Furthermore, a timing valve 26 consisting of a rotary valve is provided in the supercharging passage 13 downstream of the supercharging control valve 22.

In addition, the supercharging 120 and the supercharging air control valve 22
A communication passage 27 is formed between the supercharging passage 13 located further downstream and the surge tank 18 of the main intake passage 12 . This communication passage 27 is provided with a pressure valve 28 that opens when the supercharging pressure exceeds a predetermined value, and a timing valve 29 made of a rotary valve is provided downstream thereof. The pressure valve 28 has a valve body 28C@ which is urged in the valve closing direction by a spring 28b of a diaphragm actuator 28a, and a pressure horn chamber 28d of the actuator 28a is connected to the downstream supercharging passage 13 of the supercharger 20. 2
8e, and a supercharging pressure equal to or higher than the set pressure determined by J: is communicated with the spring 28b to the pressure horn chamber 28d.
When the pressure is applied to the relief valve 24, the valve body 28C is compressed by 1 ttl, and this set pressure is approximately the same as or lower than the set pressure of the relief valve 24. Further, the timing valve 29 it of the communication passage 27 and the timing valve 26 of the supercharging passage 13 are linked to the engine output #d21 via the pulleys 31 to 33 and the belt 34, and are opened and closed in synchronization with the engine. It has become. And the above communication path 2
As will be described in detail later, the timing at which the timing valve 29 of No. 7 is opened and closed is such that the compressed air sent to the main intake passage 12 through the communicating passage 27 in red during the operating range in which the pressure valve 28 is opened is the main intake air at the end of the intake stroke. It is set to reach near boat 4.

In the case of this device, the main intake valve 7, the supercharging intake valve 8
and the opening/closing timing of each timing valve 26, 29,
If the intake pressure near the main intake boat 4 when the pressure valve 28 is open is not shown in correspondence, the result will be as shown in FIG. 2. J, the main intake valve 7 is opened during a predetermined period of the intake stroke as shown by line A, and the supercharging intake valve 8 is opened as shown by line BC.
The main intake valve 7 is opened and closed somewhat later than the main intake valve 7. The timing valve 26 of the supercharging passage 13 is indicated by line C.
It is opened at the end of the intake stroke, and during the period when both the timing valve 26 and the supercharging intake valve 8 are open, supercharging air is supplied from the supercharging passage 13 to the combustion chamber 3. It has become so.

In addition, the timing valve 29 of the communication passage 27 controls the compressed air (
After the supercharging air passes through the timing valve 29, the communication passage 27
The opening/closing timing is set to be earlier than the end of the intake stroke by the time required to reach the vicinity of the main intake boat 4 via the main intake passage 12.

With such a setting, the intake pressure near the main intake boat 4 where the supercharging pressure is equal to or higher than a predetermined value becomes as shown by curve F and J. In other words, the pressure in the vicinity of the main intake boat 4"c gradually decreases after the main intake valve 7 is opened, and after the negative pressure reaches its maximum during the intake stroke, I mocha gradually increases. Then, at the end of the intake stroke In this case, the intake pressure is increased due to the inertia of the intake air, and compressed air, which is a part of the supercharged air discharged from the supercharger 1!20, passes through the communication passage 27 and the main intake passage 12 to the vicinity of the main intake boat 4. Therefore, the intake pressure is further increased than when no compressed air is sent (indicated by broken line F?1).

Therefore, even in the operating range where the supercharging pressure increases and the flow resistance of the supercharging passage 13 increases, the supercharging air that cannot be supplied from the supercharging passage 13 is supplied from the main intake boat 4 to the combustion chamber 3 at the end of the intake stroke. be done. At the same time, the main intake passage 12
This will prevent the supercharged air from being blown back to. In particular, the operating range and timing at which supercharging air is sent to the main intake boat 4 is limited to the operating range where the supercharging pressure is equal to or higher than a predetermined value and at the end of the intake stroke for the following reasons. In other words, when the supercharging pressure is relatively low, the supercharging air discharged from the supercharger 20 can be sufficiently fed into the combustion chamber from the supercharging passage 13, and at a time earlier than the end of the intake stroke, the supercharging air discharged from the supercharger 20 can be sent into the combustion chamber. The internal pressure is low and sufficient natural intake air can be taken in, and if the supercharged air is sent to the main intake boat 4 even at these times, the amount of natural intake air will decrease, the intake air humidity will increase, and the charging efficiency will actually decrease. This is because the amount decreases.

In this device, the supercharger 20 may be always linked to the engine output @21, but by interposing a clutch mechanism in the transmission mechanism, overload can be prevented at low loads when supercharging is not necessary. The feeder 20 may be stopped.

Further, the supercharger 20 may be a supercharger other than a positive displacement pump, for example, a turbo supercharger. In general, the valve body 28G of the pressure valve 28 may be provided in the downstream communication passage 27 of the timing valve 29.

(Effects of the Invention) As described above, the present invention allows compressed air to be sent from downstream of the supercharger to the main intake passage through the communication passage when the boost pressure in the supercharging passage reaches a predetermined value or higher. , and because the timing at which this compressed air reaches the opening of the main intake passage to the cylinder is the end of the intake stroke, the overload to the cylinder is reduced in the operating range where the supercharging pressure is high and the flow resistance of the supercharging passage increases. It is possible to increase the amount of air supplied and to prevent air from blowing back into the main intake passage, and these effects can significantly improve output.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing an embodiment of the present invention, and Fig. 2 shows the correspondence between the opening/closing timing of the main intake valve, the supercharging intake valve, and the timing valve, and the intake pressure in the vicinity of the main intake port 1. FIG. 1... Engine cylinder, 12... Main intake passage, 13
...supercharging passage, 20...supercharger, 27...communication passage, 28...pressure valve, 29...timing valve. 1st figure 1λ/〃 2nd figure 1νL−βνO

Claims (1)

[Claims] 1. In an engine having a main intake passage and a supercharging passage having a supercharger, a communication passage is formed that communicates the supercharging passage downstream of the supercharger with the main intake passage, This communication passage has a pressure valve that opens when the boost pressure exceeds a predetermined value, and opens and closes in synchronization with the engine! 718J-A timing valve is installed, and the timing at which this timing valve opens is set so that the compressed air sent to the main intake passage via the communication passage reaches the opening of the main intake passage to the cylinder (near J) at the end of the intake stroke. An intake system for a supercharged engine, characterized in that it is set as follows.