JPS62165535A - Supercharger mounted internal combustion engine - Google Patents

Abstract

PURPOSE:To improve the efficiency of supercharging by enabling the ring-type space between the end face of rotors and the bearing seal part in a mechanical- type supercharger consisting of a Roots pump to be connected through a control valve to the atmospheric air, and then causing the control valve to operate in its closing direction. CONSTITUTION:A Roots pump comprising the supercharger has a structure where two rotors 21, 40 are placed in a housing so that they may be free to rotate, and supercharges an engine with intake air in such a way that the two rotors 21, 40 are caused to rotate through the engagement of gears 29, 30 by the engine rotation transmitted to a pulley 43. In this case, a ring-type space 47 is formed between the labyrinth part 46, which is located between the end face of the rotor 21 and the main body of the housing 50, and the bearing oil-seal part 38. Said ring-type space 47 can be connected, from a port 48 passing through a control valve 9 and a passage 8, to the atmospheric air. In addition, the control valve 9 is controlled by an ECU 13 to operate in its closing direction so as to reduce the flow passage area of the passage 8 only when the engine speed, at the time of idling, is not more than a fixed value, and supercharging is being performed.

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.

[Conventional technology]

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, creating a pressure difference on both sides of the bearing. As a result, the ability to retain the grease that lubricates the bearing is reduced. In order to improve the deterioration in grease retention performance caused by such pressure differences, a labyrinth section is provided between the rotor and the bearing, and the space between the bearing and the labyrinth section is communicated with the atmosphere to reduce the intake pressure applied to the bearing. A configuration has been proposed that allows

In such a configuration, the clearance between the labyrinth part and the shaft needs to be large to some extent in order to avoid contact, and in this case, the communication port with the atmosphere needs to be large in order to obtain a sufficient intake pressure reduction effect. 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.

In order to solve this problem, the applicant has already filed a patent application [59-
In No. 135217, an annular space is formed around the rotor shaft and between an end face of the rotor and a sealing part of the bearing, and this annular space is communicated with the atmosphere through a control valve, so that low-temperature conditions such as idle operation can be avoided. We proposed a configuration in which only the intake air volume region is isolated from the atmosphere, thereby preventing an increase in idle speed.

[Problem that the invention seeks to solve]

However, in the above-mentioned proposed device, the annular space is communicated with the atmosphere even in the supercharging region at low rotation speeds, so a part of the supercharging pressure generated in the rotor chamber at this time is transferred to the atmosphere through the annular space. As a result, there was a problem that the supercharging efficiency was reduced and the output torque was not sufficiently increased. This problem becomes particularly noticeable in the low rotation range, and the output decreases greatly.

[Means for solving problems]

In order to solve the above-mentioned problems, the supercharged internal combustion engine according to the present invention connects the annular space to the atmosphere through an atmosphere introduction passage, and also provides a control valve in the middle of the atmosphere introduction passage. However, it is characterized by a configuration in which the control valve is not closed or the flow path area is reduced to prevent atmospheric air from entering even during idle and low-speed supercharging.

〔Example〕

The present invention will be explained below with reference to illustrated embodiments.

FIG. 3 is a schematic diagram showing the entire supercharged internal combustion engine according to an embodiment of the present invention.

In Fig. 3, ■ 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 is an intake pipe, 6 is an engine body, 9 is a control valve, and I3 is an electronic control unit (ECU) including a microcomputer. As will be described later, the control valve 9 controls opening and closing between a passage 7 that communicates with the labyrinth part of the supercharger 4 and the space between the bearing tube and a passage 8 that communicates upstream of the throttle valve 3 and has a pressure close to atmospheric pressure. , are controlled by signals from the ECU 13.

The ECU 13 includes an idle switch 61, a clutch 62 of the supercharger 4, an air flow meter 63, and a rotation speed sensor 64.
, the opening and closing of the control valve 9 based on input signals from the pressure sensor 65 and the like. The idle throttle valve 1 is turned on when the opening degree of the throttle valve 3 is less than or equal to a predetermined value, and outputs a signal indicating that the engine is in an idle operating state. When the clutch 62 is engaged, it outputs a signal indicating that supercharging is in progress, and the air flow meter 63 outputs a signal corresponding to the intake air amount Q. A rotation speed sensor 64 is provided in the distributor and outputs a signal indicating the engine rotation speed, and a pressure sensor 65 is provided in the intake passage downstream of the supercharger 4 and outputs a signal corresponding to the intake pipe pressure. The control valve 9 can be configured as a well-known electromagnetic valve including a valve seal 10, a spring 11, and an electromagnetic coil 12.

FIG. 2 is a sectional view of a supercharger consisting of a roof 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. A rotor shaft 22 supporting the rotor 21 on the upper side of FIG. 1 is rotatably supported at both ends by bearings 28 and 37. 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 the pulley 4
3 is fixed. each rotor shaft 22
, 23 are configured to be mutually transmitted by gears 29, 30.

That is, each rotor shaft 22, 23 is supported by bearings on both sides of the rotor. each rotor shaft 22,
23 extends further to the right side than the bearing on the right side as seen in FIG. 2, and similar gears 29 and 30 are installed at the extended end.
are installed respectively. In the illustrated structure, the inner ring of the bearing engages with the stepped portion of each rotor shaft, the inner periphery of gears 29 and 30 engage with these inner rings, and each gear 29 and 30 engages with a washer 32. The rotor shafts 22 and 23 are fastened to the respective rotor shafts 22 and 23 by screws 44 or the like. gear 29
, 30, the bearing, and the tip of the rotor shaft, a cover 33 is attached to the rear plate 51 to form an oil chamber. A suitable amount of oil is sealed in the oil chamber to lubricate the gears 29 and 30 and the bearings. pulley 4
The rotation of the engine crankshaft is transmitted to rotor 21 and 4 by the shown belt.
It is well known to supercharge the intake air to the engine by rotating the engine. The left end portion of the shaft 22 protrudes from the housing body 51, and the portion protruding from the bearing 37 is covered with a cap 39.

Next, the structure of the bearing portion that rotatably supports the rotor shirts 22 and 23 will be described in detail using the bearing 37 on the upper left side of FIG. 2 as an example. The bearing 37 is an oil-lubricated type bearing, and an oil seal 38 is provided on the rotor 2 side to prevent oil from leaking out. There is a gap in the axial direction between the end face of the rotor 21 and the housing body 50, forming a so-called labyrinth portion 46. A port 48 is connected to the annular space 47 between the labyrinth portion 46 and the bearing oil seal 38, and further,
This port 48 is connected to the control valve 9 via the passage 7, and also communicates with the atmosphere upstream of the throttle valve 3 (third section) via the control valve 9 and the passage 8.

FIG. 1 shows a flowchart of a program for controlling the opening and closing of the control valve 9 by the ECU 13. This program is interrupted at predetermined time intervals. First, in step 101,
It is determined whether the idle switch 61 is in an ON state, that is, whether the internal combustion engine is in an idling state. If it is in an idling state, step 104 is executed, and the control valve 9 is closed by demagnetizing the electromagnetic coil 12. Conversely, if it is in an idling state, step 102 is executed, and the engine speed is set to a predetermined value. It is determined whether or not the value is less than or equal to the value.

This determination is made by the rotation speed sensor 64. When the rotational speed is equal to or higher than the predetermined value, step 105 is executed and the control valve 9 is opened. That is, the annular space 47 is opened to the atmosphere. Conversely, if the rotational speed is below the predetermined value in step 102, step 103 is executed, and it is determined whether the operating state of the internal combustion engine is in the supercharging range. Judgment as to whether or not it is in this supercharging range is based on the ratio Q/N of intake air IQ and engine speed N.
Alternatively, this may be performed by determining whether the intake pipe pressure is equal to or higher than a predetermined value, and the clutch 62 of the supercharger 4
This may be done by determining whether or not they are in a connected state. If it is determined in step 103 that the engine is in the supercharging region, step 104 is executed and the control valve 9 is closed. In this case, for example, the valve may be closed for a predetermined period of time only during the initial stage of supercharging, and thereafter opened. This is particularly effective in cases where only the output drop at the initial stage of supercharging is a problem. Such time control is performed, for example, by demagnetizing the electromagnetic coil 12 for a predetermined period of time.

Limiting the demagnetization of the electromagnetic coil 12 to only a predetermined period of time in this manner is achieved by using a timer (not shown). On the other hand, if it is determined in step 103 that the supercharging region is not reached, step 105 is executed, and the control valve 9 is opened by energizing the electromagnetic coil 12.

Therefore, when the internal combustion engine is started and enters the idle operating state, steps 101, 104 are executed in sequence, the control valve 9 remains closed, and when the internal combustion engine enters the normal operating state, steps 101, 102, 105 or Step 101.
102, 103, and 105 are executed in this order, and the control valve 9 maintains the open state. When the internal combustion engine enters the supercharging region at low rotation speed, steps 101, 102, 103, and 104 are executed in this order, and the control valve 9 is closed (for a predetermined time) and then opened again. Thereafter, each time the engine enters the supercharging region at low rotation speeds, the control valve 9 repeats the operation of closing for a predetermined period of time and then opening. - Intake pressure acts on the bearing 37 through the inside of the housing 50, that is, the rotor chamber, and the labyrinth part 46. During normal operation, the control valve 9 is energized and the spring 11 is activated by the force of the electromagnetic coil 12. Since the valve body 10 is attracted by the valve element 10 and the passage 7 and the passage 8 are communicated with each other, the atmospheric pressure upstream of the throttle valve 3 (FIG. 3) is introduced into the annular space 47 and bled, so that the pressure is reduced. is sufficiently small.

Therefore, the grease sealed in the bearing is not pushed out through the bearing 37.

On the other hand, during idling operation, the ECU 13 turns off the power to the control valve 9. As a result, the valve body 10 of the control valve 9
blocks the passages 7 and 8 by the force of the spring 11. As a result, intake pressure acts on the bearing oil seal portion, but since the rotation is low, there is no adverse effect on the characteristics of the oil seal, and at the same time, atmospheric air is sucked into the intake pipe via the labyrinth portion 46 and The amount of intake air is prevented from increasing, and therefore the engine speed is prevented from increasing.

In addition, since the control valve 9 closes even during supercharging at low rotation speeds,
The high-pressure air generated in the rotor chamber is not released into the atmosphere via the annular space 47, the passage 7, etc., and a decrease in supercharging pressure is prevented.

Therefore, the supercharging pressure of intake air supplied to the combustion chamber of the internal combustion engine is increased, and acceleration performance is improved. If the operation of closing the control valve 9 when entering the supercharging region at low rotation speeds is limited to a predetermined period of time (for example, several seconds) as described above, the grease in the bearing will become hot and viscous during this time. There is no fear that it will drop and leak to the outside.

In addition, in the above embodiment, the control valve 9 is closed when supercharging is reduced at low rotation speeds, but the control valve 9 does not necessarily have to be fully closed, and the flow path area can be narrowed down to a certain value or less. You can do it like this. Further, the control valve 9 does not need to be a solenoid valve, and may be one that opens and closes using negative pressure, such as a diaphragm device, for example.

The other bearings of the rotor shirts L-22 and 23 are constructed in exactly the same manner, and the annular space 47 between the labyrinth part and the bearing oil seal part is inside the housing body 50 and rear brake 51. It is connected to the passageway 7 through a port 48 formed in the passageway 7 .

In addition, the pump efficiency (corresponding to supercharging pressure) of the Roots pump is as shown in Figure 4, with respect to the pump rotation speed, as shown in Figure 4, the efficiency is lower when the air intake is canted (solid line) than when the air intake is continued (broken line). Up. Therefore, as shown in FIG. 5, the torque characteristic with respect to the engine speed is such that according to the present invention, the torque can be increased in the low speed range.

〔Effect of the invention〕

As described above, according to the present invention, even if intake pressure acts on the bearing during normal operation, the pressure difference acting on the bearing is reduced due to atmospheric bleed, and the function of retaining the grease that lubricates the bearing is improved. Well maintained by oil seals. Further, during idling operation, an increase in the amount of intake air and an increase in the engine speed are prevented. Further, in the supercharging region at low rotation speeds, the supercharging pressure can be sufficiently increased without impairing the durability of the supercharger, and the supercharging efficiency of the vehicle can be improved. In particular, improvement in supercharging efficiency in the low rotation range can be achieved while maintaining the basic configuration of the proposed device, and can be achieved without increasing costs.

[Brief explanation of drawings]

FIG. 1 is a flowchart showing the control by the electronic control unit in the supercharging region according to the present invention, FIG. 2 is a sectional view showing a supercharger comprising a Roots pump according to an embodiment of the present invention, and FIG. Figure 2 is a schematic diagram showing an internal combustion engine equipped with a supercharger, Figure 4 is a characteristic diagram showing pump efficiency versus pump rotation speed with and without introduction of atmospheric air, and Figure 5 is a diagram showing the effects of the present invention. Torque characteristic diagram with respect to engine speed. 4...Supercharger (roots pump), 7.8...Passage, 9...Control valve, 13...
・Electronic control unit, 21, 40... rotor, 22
, 23... Rotor shaft, 38... Oil seal, 28... Bearing, 47...
- Annular space part, 48...Boat, 50...Housing, 51...Rear plate. 4 Supercharger (Roots pump) 22.23... Rotor shaft 7.8 Passage 28 Bearing 9
・・Control a valve 38・Oil seal 13・
・Electronic control section 47'...Annular space section 2140
Rotor 50/Housing 7.8 Passage 22.23- Rotor shaft 28 Bearing Figure 3 Figure 4 Figure 5 Procedural amendment (voluntary) January 1, 1986 Michibu Uga, Commissioner of the Patent Office 1, of the case Indication: 1985 Patent Application No. 007190 2, Title of invention: Internal combustion engine with supercharger 4, Agent address: 105 IO, Toranomon-chome-8, Minato-ku, Tokyo (4 others) ゛5, Subject of amendment ( 1) “Detailed Description of the Invention” column of the specification (2) Drawings (
(Fig. 5) 6. Contents of the amendment (1) “Valve closed” stated on page 4, line 20 of the specification
is corrected to "close the valve." (2) Correct the drawing (Figure 5) as shown in the attached sheet. 7. List of attached documents

Claims (1)

[Claims] 1. The two rotors, which are rotatably supported by bearings in the pump housing, rotate while meshing with each other while maintaining a predetermined clearance between them and the inner circumferential surface of the housing, pumping a fixed volume of fluid into the suction side with each rotation. In an internal combustion engine with a mechanical supercharger equipped with a Roots pump that sucks and discharges air from the rotor to the discharge side, an annular space is formed around the rotor shaft and between the end face of the rotor and the seal portion of the bearing, and The annular space is connected to the atmosphere through an air introduction passage, and a control valve is placed in the air introduction passage to change the flow area according to the operating conditions of the internal combustion engine, and the idle state of the internal combustion engine is detected. An idle detection means for detecting the engine rotation speed, a rotation speed detection means for detecting the engine rotation speed, and a supercharging detection means for detecting the supercharging state are provided. An internal combustion engine with a supercharger, characterized in that the control valve is operated in the valve closing direction to reduce the flow path area only when the control valve is being operated.