JPS6321332A - Internal combustion engine with supercharger - Google Patents

Abstract

PURPOSE:To improve the durability of a supercharger and prevent increase in idling engine speed by providing a passage for bypassing a control valve and feeding a large quantity of air at the time of idling, on an air introducing passage. CONSTITUTION:A control valve 9 is closed at the time of idling or a low engine speed condition. And, the air passes through a bypass 15, a throttle valve 16 and a bypass 14 and is fed to an annular space part formed in between a rotor end face and the seal part of a bearing, on the periphery of the rotor shaft. When the engine speed is above a defined value, the control valve 9 is opened and the air flows into the annular space part via the control valve 9 and the bypasses 14, 15.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a supercharged internal combustion engine equipped with a Roots pump.

[Prior art]

Roots pumps for internal combustion engines with a supercharger have bilobed rotors attached to two rotor shafts, and the pumping action is achieved by rotating these rotors in synchronization in opposite directions. There is. A small amount of clearance is typically provided between the rotors and between the rotors and the housing. Therefore, it is inevitable that the discharged air on the high pressure side leaks to the low pressure side through these clearances. As a result, the pressure of the leaked air from the rotor side acts on the bearings that support both ends of the rotor shaft, and pressure is generated on both sides of the bearing. for that,
This will reduce the ability to retain oil or grease that lubricates the bearings. In order to improve the deterioration in oil or grease retention performance caused by such pressure differences, a labyrinth is provided between the rotor and the bearing, and the space between the bearing and the labyrinth is communicated with the atmosphere to reduce the intake pressure applied to the bearing. It is proposed to reduce

In addition, in Roots pumps for internal combustion engines with a supercharger, the clearance between the shaft of the labyrinth part mentioned above must be set to a certain extent to avoid contact, and in this case, in order to obtain a sufficient intake pressure reduction effect, the clearance between the labyrinth part and the shaft must be set to a certain extent. It is also necessary to take a large distance. However, when this is done, in engine operating ranges where the amount of intake air is small, such as idling, the atmospheric air is sucked into the engine through the labyrinth, which substantially increases the amount of intake air, causing the throttle valve to tighten. However, the problem is that the engine speed cannot be lowered sufficiently. (
(Idle amplifier) Therefore, in order to sufficiently reduce the intake pressure applied to the bearing and to prevent the engine rotation from increasing in a region where the amount of intake air is small, such as during idling operation, it is necessary to The annular space formed between the internal combustion engine and the seal part is connected to the atmosphere through an atmosphere introduction passage, and the air introduction passage is provided with a control valve that opens and closes depending on the operating conditions of the internal combustion engine. An internal combustion engine has been proposed. (Unexamined Japanese Patent Publication No. 61-1623
No. 2) [Problem to be solved by the invention] In a supercharged internal combustion engine having the above control valve, when the engine is idling, the control valve is closed to stop the introduction of air into the annular space and prevent the engine rotation from increasing. However, considering the durability of the supercharger, it is desirable to introduce a small amount of air even during idling operation, even if not during high rotation times. In other words, an air intake control valve that introduces a small amount of air to suppress the increase in rotation speed during idle operation or low rotation, and introduces a large amount of air to reduce the intake pressure on the bearing during high rotation. However, variable type control valves have the problem of complicated structures and increased manufacturing costs. In view of these problems, the object of the present invention is to introduce a small amount of air during idling and a large amount of air during high rotation, without affecting the durability of the supercharger, and to have a simple structure. The purpose of the present invention is to provide an air introduction mechanism that does not increase manufacturing costs.

[Means for solving problems]

According to the present invention, the annular space formed around the rotor shaft and between the rotor end face and the seal portion of the bearing is connected to the atmosphere through the atmosphere introduction passage, and the internal combustion engine is connected to the atmosphere introduction passage. A supercharged internal combustion engine is provided with a control valve that opens and closes depending on operating conditions, and the air intake passage bypasses the control valve to supply an appropriate amount of air to the annular space when the engine is idling. A supercharged internal combustion engine is provided that is characterized by being provided with a bypass passage.

〔Example〕

Preferred embodiments of the invention will now be described with reference to the accompanying drawings.

First, the structure of a supercharger, which is the basis of the present invention, will be explained.

FIG. 3 is a sectional view of a supercharger consisting of a Roots pump.

In FIG. 2, 50 is a housing body, 51 is a rear plate that closes one open end of the housing body, and the housing body 50 and the rear plate 51 form a pump housing. Inside this pump housing, two rotors 21 and 40, each having a bilobal shape unique to Roots pumps, are installed on respective rotor shafts 22 and 2.
3. 24 is a pin for fixing the rotor 21 to the rotor shaft 22. The rotor shaft 22 supporting the rotor 21 on the upper side of FIG. 3 is rotatably supported at both ends by bearings 2B and 37, and at the same time has a pulley 43 fixed thereto. Another lower rotor 40 is similarly fixed to the rotor shaft 23, and this rotor shaft 23 is also rotatably supported by bearings at both ends, and each rotor shaft 22
, 23 are configured so that rotation is transmitted through gears 29 and 30.

That is, each rotor shaft 22, 23 is supported by bearings on both sides of the rotor. Each of the rotor shafts 22 and 23 extends further to the right than the bearing on the right side as viewed in FIG. 3, and similar gears 29 and 30 are respectively attached to the extended ends thereof. In the illustrated structure, the inner rings of the bearings engage with the stepped portions of the respective rotor shafts, the inner circumferences of the gears 29 and 30 engage with these inner rings, and the inner rings of the bearings engage with the stepped portions of the respective rotor shafts.
30 are attached to the respective rotor shafts 22 and 23 with washers 32, screws 44, and the like. A cover 33 is attached to the rear plate 51 to cover the gears 29 and 30, the bearings, and the tip of the rotor shaft, forming an oil or grease chamber.

An appropriate amount of oil or grease is sealed in the oil chamber (grease chamber) to lubricate the gears 29, 30 and bearings. It is well known that the rotation of the crankshaft of the engine is transmitted to the pulley 43 by a belt (not shown), thereby rotating the rotors 21 and 40 and supercharging the intake air to the engine.

Next, the structure of the bearing portion that rotatably supports the rotor shirt 1-22, 23 will be described in detail using the bearing 28 on the right side of FIG. 3 as an example. The bearing 28 is an oil-lubricated type bearing, and an oil seal 27 is provided on the rotor 21 side. There is a gap in the axial direction between the end face of the rotor 21 and the rear plate 51, and a so-called labyrinth portion 4
6 is formed.

In order to prevent oil or grease from leaking from the bearings 2B, 37 to the labyrinth part 46 via the oil seal 27 due to the intake pressure generated by the rotation of the rotors 21 and 40, in the prior art, the labyrinth part 46 and the bearing oil seal 27 are connected. A boat 48 is connected to the annular space 47 between them, and furthermore,
In order to prevent the engine speed from increasing during idling operation, the boat 48 is connected via a passage 7 to a control valve 9 that can be opened and closed, and is also communicated with the atmosphere via the control valve 9 and a passage 8. .

Examples of the present invention will be described below.

FIG. 1 is a schematic diagram showing the entire supercharged internal combustion engine according to the present invention.

In Figure 1, 1 is an air cleaner, 2 is an air flow meter, 3 is a throttle valve, 4 is a supercharger consisting of a roots pump, 5
1 is an intake pipe, 6 is an engine body, 9 is a control valve, and 13 is a computer. As described above, the control valve 9 includes a passage 7 communicating with an annular space 47 (FIG. 3) between the labyrinth portion 46 (FIG. 3) of the supercharger 4 and the bearing 28 (FIG. 3);
Opening and closing between the throttle valve 3 and a passage 8 communicating upstream of the throttle valve 3 and having a pressure close to atmospheric pressure is controlled by signals from a computer 13. The computer 13 detects the idle operating state of the engine using one or a combination of signals from various sensors such as an engine speed sensor, vehicle speed sensor, throttle opening sensor, air flow meter, etc., and controls the control valve 9.

The control valve 9 includes a valve body 10, a spring 11, and an electromagnetic coil 1.
It can be configured as a well-known electromagnetic valve configured by 2.

According to the invention, the passages 7 and 8 are also provided in parallel with the control valve 9.
Bypass passages 14 and 15 are provided which communicate with the passages 7 and 8 and have a diameter smaller than that of the passages 7 and 8.
A throttle valve 16 is provided between the valve 5 and the valve 5. The operation of the supercharged internal combustion engine of the present invention constructed as described above is illustrated in FIGS. 1 and 4.
This will be explained below with reference to the figures. Figure 4 shows the computer 13
5 shows a flowchart of a program for controlling the opening and closing of the control valve 9. This program is interrupted at predetermined time intervals. First, in step 101, it is determined whether the internal combustion engine is in an idling state. If the engine is not in an idling state, step 102 is executed and it is determined whether the engine speed is equal to or higher than a predetermined value. When the rotational speed is equal to or higher than the predetermined value, step 103 is executed and the control valve 9 is opened.

In step 101, the engine is in idle operation;
ll, or if the engine speed is below the predetermined value in step 102, step 104 is executed and the control valve 9 is closed. However, the atmosphere passes through the bypass passage 15, the throttle valve 16, and the bypass passage 14, and is supplied to the annular space 47, and the amount of air is appropriately controlled by the throttle valve 16, so that the supercharger has a long lifespan. This makes it possible to prevent the idle speed from increasing without impairing performance.

On the other hand, when the engine speed of the engine is above a predetermined value, that is, when accelerating or decelerating due to downshifting, the bearings 28, 3
7, a considerable intake pressure is generated, so a large amount of atmospheric air must be introduced to alleviate this. When the control valve 9 opens in step 103, the control valve 9 and the bypass path 1
4 and 15, the atmosphere enters the annular space 47 (Fig. 3)
By flowing into the oil or grease, it is possible to maintain the oil or grease retention performance, which is the original purpose.

FIG. 2 is a schematic diagram showing another embodiment different from FIG. 1. In this figure, reference numerals common to those in FIG. 1 have the same effects as in FIG. 1. In this embodiment, in addition to the bypass passages 14 and 15 shown in FIG. 1, a passage 19 is provided which opens into the intake pipe 5 downstream of the throttle valve 3. Bypass path 14 via
communicate with.

Further, the diameter of the passage 19 is formed larger than the diameter of the bypass passages 14 and 15. The operation of this embodiment will be explained below.

When the engine is in idle operation, the throttle valve 3 is in a substantially closed state, so negative pressure is generated in the intake pipe 5 on the downstream side of the throttle valve 3.

Therefore, the check valve 18 is in an open state, and at this time, the amount of air introduced into the annular space 47 (FIG. 3) is the same as that in the embodiment shown in FIG. The engine speed will not increase.

Next, if the throttle valve 3 is opened more than during idling operation,
The pressure in the intake pipe 5 is approximately equal to atmospheric pressure, and the pressure in the bearings 28 and 3 is approximately equal to atmospheric pressure.
7 (FIG. 3), the check valve 18 is opened due to the negative pressure, and at the same time, the atmosphere controlled by the throttle valve 17 is introduced into the annular space 47 (FIG. 3) through the passage 19. In this case as well, the introduction of the atmosphere from the bypass paths 14 and 15 continues, so the amount of air introduced here is equal to that of the throttle valve 16.
and the amount of air controlled by the throttle valve 17.

Then, when the intake air amount increases (during acceleration) when the throttle valve 3 is opened, or during deceleration when the suction pressure increases, step 103 shown in FIG. 4 is executed, and in addition to the sum of the above air amounts, the control valve Since a large amount of air is introduced through the pipe 9, the oil or grease retention performance is maintained.

That is, the embodiment shown in FIG. 2 is different from the first embodiment (FIG. 1) which has two levels of introduced air amounts, to the annular space 47 (FIG. 3) from the suction pipe 5 via the check valve 18. An embodiment is intended in which the flow rate is increased to three levels by providing a passage 19 for introducing atmospheric air, and by doing so, it becomes possible to switch the atmospheric air introduction more precisely. In this figure, the passage 19 communicates with the bypass passage 14, but it may also communicate with the passage 7, and the effect is the same. In addition, by providing two or more positions and diameters of the passage 19 that opens into the intake pipe 5, it is possible to switch the amount of air introduced into three or more levels.

In addition, the first embodiment (Fig. 1) and the second embodiment (
(Fig. 2) An annular space 47 (Fig. 3) in each passage 15.
It is also possible to prevent the supercharging pressure from decreasing during supercharging at low rotation speeds by providing a check valve (not shown) that prevents air from flowing back into the atmosphere.

〔Effect of the invention〕

As described above, according to the present invention, in addition to the conventional on-off type control valve, a passage is provided to bypass a small amount of atmospheric air during idling, thereby improving the durability of the supercharger and preventing an increase in idling speed. is possible. Furthermore, it is possible to provide a control mechanism that has a simpler structure and is cheaper to manufacture than a variable type control valve.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a supercharged internal combustion engine according to one embodiment of the present invention; FIG. 2 is a schematic diagram showing a supercharged internal combustion engine according to another embodiment of the present invention; FIG. FIG. 4 is a flowchart showing computer control in the supercharger according to the present invention. 4...Supercharger (roots pump), 7.8...(atmosphere introduction) passage, 9...control valve, 13
... Computer, 14, 15... Bypass path, 21, 40.
...Rotor, 22, 23...Rotor shaft, 2
8, 37... bearing, 47... annular space part. 9... Control valve 13... Conbeater 14.15... Bypass path Figure 1 Figure 4 Condolences 3 Figure

Claims (1)

[Claims] An annular space formed around the rotor shaft and between the rotor end face and the seal of the bearing is connected to the atmosphere via an atmosphere introduction passage, and the atmosphere introduction passage is opened and closed depending on the operating conditions of the internal combustion engine. A supercharged internal combustion engine is provided with a control valve for controlling the engine, and the air introduction passage is provided with a bypass passage that bypasses the control valve and supplies an appropriate amount of air to the annular space when the engine is idling. An internal combustion engine with a supercharger.