JPS6390634A - Engine with supercharger - Google Patents

Abstract

PURPOSE:To improve the extent of idling stability, by installing an atmospheric intake passage in a casing of a mechanical supercharger as interconnected to a ring space to be formed around a rotor support shaft of the supercharger, and installing a control valve to be opened at time of detection of current consumer operation, in this passage. CONSTITUTION:In case of a supercharger 20, consisting of a Roots pump or the like having a pair of rotors 22 installed in a suction passage 12 and driven by an engine, a ring space 36 surrounding a support shaft 26 is formed between an end face of the rotors 22 and a bearing 28 supporting this rotor support shaft 26 free of rotation to a casing 24. This ring space 36 is opened to the atmosphere by a port part 38 passing through the casing 24 and an atmospheric intake passage consisting of a pipe part 40 extending to the atmospheric intake port formed at the upstream side of a throttle valve in the suction passage 12. And, a control valve 42 is installed in the point midway in this atmospheric intake passage, and it is controlled by an electronic control unit 52 so as to be opened at the time of detection of operation of a current consumer 54 for an air conditioner and a light or the like.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an engine equipped with a mechanical supercharger.

[Conventional technology]

JP-A-61-16232 discloses an engine equipped with a mechanical supercharger. A portion of the boost pressure leaks from the end face of the rotor and is applied to the bearing, reducing the bearing's ability to retain lubricant. This publication discloses that in order to ensure the lubricant holding capacity of the bearings of a supercharger, the supercharging pressure applied to the bearings is bled to the atmosphere, and that the supercharging pressure applied to the bearings is bled to the atmosphere at times such as when idling. A control valve is provided in order to prevent the negative pressure from acting and additional air being sucked in from the bleed passage, causing the engine speed to rise.

[Problem that the invention seeks to solve]

By the way, when an electric load such as an air conditioner or a light is activated in an engine installed in an automobile, a load is applied to the alternator, and the idle speed decreases, which may lead to unstable idle. Conventionally, if there is a concern that such idle instability may occur, idle amplifier means has been required to increase the idle rotation speed when the electric load is activated.

[Means for solving problems]

A supercharged engine according to the present invention is an engine equipped with a mechanical supercharger configured with a Roots pump, in which an end face of a rotor of the supercharger and a support shaft of the rotor are supported within a casing of the supercharger. An air introduction passage is connected to an annular space formed around the support shaft, and a control valve is disposed in the middle of the air introduction passage, and a means for detecting operation of the electric load is provided. , the control valve is opened when the operation of the electric load is detected.

〔Example〕

In FIG. 1, 10 indicates the engine body, and the engine body 10
As is known in the art, a piston (not shown) is inserted therein so as to be able to reciprocate, and the piston is connected to the crankshaft by a connecting rod. An intake passage 12 and an exhaust passage 14 are communicated with the combustion chamber of the engine body 10, and an intake valve and an exhaust valve are arranged in each of them.

As is well known, the intake passage 12 is formed by an intake pipe, an intake manifold, and an intake port, and includes, in order from the upstream side, an air cleaner 16, an air flow meter 17, a throttle valve 18,
A supercharger 20 and a fuel injection valve (not shown) are arranged. The supercharger 20 is composed of a roots pump having a cocoon-shaped rotor 22, and is attached to the support shaft of one of the rotors 22! The magnetic latch is connected to the crank pulley by a timing belt, so that the supercharger 20 is mechanically driven by the rotation of the engine crankshaft.

FIG. 2 is a detailed view of the supercharger 20, in which the rotor 22 is disposed within a casing 24, and the rotor 22 is disposed within a casing 24.
The support shaft 26 extends through the end wall 24a of the casing 24, and is supported by a bearing 28 in a hole wall formed through the end wall 24a.

A lubricant is applied to the bearings 28. For example, in FIG. 2, the left bearing 28 is a grease-filled type, and the right bearing 28 is
is the type that requires oil. Seal means 30 are arranged inside these bearings 28 to prevent these lubricants from flowing towards the rotor 22. Further, a gear 32 is attached to one end of the support shaft 26 of each rotor 22, and an electromagnetic clutch 34 is attached to the opposite end of one of the support shafts 26. The electromagnetic clutch 34 can be connected to the crankshaft as described above, so that the supercharger 22 is driven by the engine. Further, a cover is attached to cover the gear 32, forming an oil chamber 32a.

Furthermore, as shown in FIG. 2, an annular space 36 surrounding the support shaft 26 is formed between the end face of the rotor 22 and the bearing 28 (that is, its sealing means 30), and these annular spaces 36 are exposed to the atmosphere. It is opened to the atmosphere through an introduction passage. That is, the atmosphere introduction passage consists of a boat section 38 passing through the casing 24 and a pipe section 40 extending from the boat section 40 to the atmosphere introduction port.As shown in FIG. It is formed.

As shown in FIG.
II valve 42 is arranged. The control valve 42 is a solenoid 46
The valve member 48 has a valve member 48 that is operated by a spring 50 and is biased in the valve closing direction by a spring 50. The valve member 48 is always urged toward the closing side by the action of the spring 50, and when the solenoid 46 is energized, it is pulled by the solenoid 46 and opens. A control unit (ECU) 52 is provided to control the operation of this control valve 42, and this control unit 52 includes several sensors a and b that indicate the operating state of the engine.

C1 For example, a commonly used load sensor, rotation speed sensor,
Detection signals from the throttle position sensor, etc. are input,
Furthermore, a detection signal representing the operating state of the electric load 54 is input.

FIG. 3 is a diagram showing details of the control unit (ECU) 52. The control device 52 is configured as a microcomputer and includes a central processing unit (CPU) 5 having calculation and control functions.
6 and the read-only memory that stores the program (
Rolvi) 58 and a random access memory (JAM) 60 for storing data etc., these are interconnected by a bus 62, and receive detection signals from various sensors via an input/output interface 64. A control signal is output to the control valve 42. As mentioned above, the detection signal is generated by the air flow meter 17 and the rotation speed sensor 66.
, is input from the idle switch 68, etc., and is also input from the wiper 70 and the light 72 as electrical loads.

As schematically shown in FIG. 1, the supercharger 20 has a suction boat and a discharge boat located substantially opposite to each other in the circumferential direction of the casing 24, and performs a compression action twice for each rotation of the rotor 22. A labyrinth seal is formed between the end face of the rotor 22 and the opposing casing end wall 24a, but there is a small clearance space between them.
This minute clearance space communicates with both the suction boat and the discharge boat, and receives an intermediate pressure between the suction pressure and the boost pressure. This intermediate pressure is approximately atmospheric pressure on the upstream side of the supercharger 20 when the throttle valve 18 is fully open and the load is high.
Since the downstream side is the supercharging pressure, the pressure is approximately half of the supercharging pressure.On the other hand, when the throttle valve 18 is throttled and is at idle, both the upstream and downstream sides of the supercharger 20 have negative pressure, so it is rather It becomes negative pressure. When the intermediate pressure is a positive pressure, the intermediate pressure is led to the atmospheric pressure portion of the intake passage 12 upstream of the throttle valve 18 through the atmosphere introduction passage 40, thereby eliminating the pressure difference before and after the bearing 28. This ensures the ability of the bearing 28 to retain lubricant. On the other hand, when the intermediate pressure is a negative pressure, the supercharger 2
Additional air is drawn into the engine through the end face portion of the rotor, and additional air is drawn into the air drawn through the throttle valve 18. This intake of additional air is desirable because it raises the idle speed above the controlled level, and therefore, the control valve 42 is closed at this time to block the atmosphere introduction passage 40 and reduce such idle speed. We are trying to prevent it from rising. However, in the present invention, when the electrical load 54 is activated and it is desired to increase the idle speed, the control valve 42 is opened and the idle is increased by supplying additional air through the atmosphere introduction passage 40. It is.

As described above, the control valve 42 is opened and closed depending on the engine operating state, and is closed when the engine is idling, for example, to prevent excess air from being drawn into the engine via the atmosphere introduction passage 40 and the annular space 36, and when the engine is idling. Otherwise, it is opened to bleed the supercharging pressure in the annular space 36 to the atmosphere to prevent the supercharging pressure from creating a pressure difference on both sides of the bearing 28. In operating conditions where it is desirable that the supercharging pressure not be bled from the annular space 36, the control valve 42 can be closed even when the engine is not idling.

For example, the control valve 42 is closed for a predetermined period of time during rapid acceleration, or is closed in a low-speed supercharging region.

In this way, by preventing leakage from the air introduction passage 40, the supercharging effect can be enhanced.

FIG. 4 is a diagram showing a flowchart of the control of the control valve 42 described above, in which it is determined in step 80 whether the wiper is turned on or not, and if YES, the process proceeds to step 82, and if NO, the process proceeds to step 81. It also determines whether the light is turned on. If YES here, proceed to step 82 and set the electrical load flag f.
If no, the process advances to step 83 and the electrical load flag f is reset. After passing through steps 82 and 83, the process proceeds to step 84, where it is determined whether the electrical load flag f is set. Electrical load flag f
If is set, it is determined that the electric load is being operated, and the process proceeds to step 85, where the control valve 42 is opened regardless of other engine operating conditions. This naturally includes the idle time, and also includes the conditions under which the bearing 28 should be protected in the supercharged state. If no in step 84, the process proceeds to step 86, where it is determined whether the idle state is reached, and if yes, the process proceeds to step 87, where the control valve 42 is closed.
If no, the process advances to step 85 and the control valve 42 is opened.

FIG. 5 shows an example in which a brake lamp and a small lamp are used as electrical loads instead of the wiper and light shown in FIG. 4. In this case, since the electrical load on the brake lamp and small lamp is small, step 92 is passed only when both the brake lamp and small lamp are on in steps 90 and 91, and the electrical load flag is set. When one of them is on, the electric load flag f is reset in step 93.Steps 94 to 97 are the same as steps 84 to 87 in FIG. It detects when an element such as a wiper or a light is switched on to detect the operation of the switch, but other changes in current can also be detected.

〔Effect of the invention〕

As explained above, according to the present invention, the durability of the bearing of the supercharger can be increased by introducing atmospheric air, and the control valve disposed in the atmospheric air introducing passage can increase the idle and stabilize the idle during electrical load operation. can perform sex.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a supercharged engine to which the present invention is applied;
Figure 2 is a sectional view showing details of the supercharger, Figure 3 is a diagram showing details of the control device, Figure 4 is a diagram showing a first example of a control valve flowchart, and Figure 5 is a flowchart of the control valve. the second of
It is a figure which shows an example. 20...Supercharger, 22...Rotor, 2
6... Rotor support shaft 28... Bearing, 36...
・Annular space, 38・40...Atmosphere introduction passage, 4
2... Control valve, 54... Electric load.

Claims (1)

[Claims] In an engine equipped with a mechanical supercharger constituted by a Roots pump, the support shaft is disposed within the casing of the supercharger between an end face of the rotor of the supercharger and a bearing that supports the support shaft of the rotor. An air introduction passage is connected to an annular space formed around the air introduction passage, a control valve is arranged in the middle of the air introduction passage, and a means for detecting the operation of the electric load is provided, and the operation of the electric load is detected. A supercharged engine characterized in that the control valve is sometimes opened.