JPH07180561A - Supercharger - Google Patents

Abstract

PURPOSE:To provide a supercharger which is constituted to prevent the occurrence of a reverse flow of supercharged air by a check valve having a simple low-cost structure. CONSTITUTION:In a supercharger 1 comprising a casing 7; and a pair of rotors 3 and 5 contained in the casing 7 and driven by an engine, a plate-form check valve 17 is provided to be disposed in the vicinity of a delivery port 15 of a supercharger 1 and open and close a delivery port 15 by means of a pressure difference between the front and the rear and block the reverse flow of supercharging air in a downstream position.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positive displacement supercharger used in a vehicle or the like and mechanically driven by a crankshaft of an engine.

[0002]

2. Description of the Related Art As a conventional displacement type supercharger, a roots blower as shown in FIG. 2 is known (see "Motor Fan", page 137, issued in November 1987). This supercharger 101 is a two-leaf rotor 1
Blowers 03 and 105 are housed in a casing 107, and are arranged between a carburetor 109 and an intake manifold 111. The rotors 103 and 105 are driven by a crank shaft of an engine (not shown) via a mechanical drive mechanism. Referring to the operation of one of the rotors 103 in FIG. 3, the shaded mixture 120 enters the casing 107 through the suction port 113, and moves in the order of (a) to (d) of FIG. 3 as the rotor 103 rotates. And (e) discharge port 1
It is discharged from 15. Between the intake and the discharge, the air-fuel mixture 12
No internal compression of 0 is performed.

On the other hand, in order to increase the supercharging pressure, it is advantageous to use a so-called compressor having an internal compression function.
There are screw-type Rismolum compressors as shown in (a) and (b) (see "Car Graphic", page 197, issued in September 1988. However, Fig. 4 (b) shows industrial use).

The screw type compressor 201 is arranged at the same position as the roots blower 101, and a pair of male and female rotors 205 twisted in a casing 207 (only a part of the outline of the rotor chamber is shown in FIG. 4A). , 203
Have. The rotors 205 and 203 are driven from the crankshaft of the engine via a timing gear (not shown) provided at the shaft ends thereof. The air-fuel mixture enters the twisted tooth groove from the suction port on the left side in FIG.
While advancing to the discharge port on the right side in the axial direction of 3, the discharge is gradually compressed from A in FIG. 5A to B in FIG. 5B and discharged. A slide valve (not shown) is provided at the discharge port.
Is provided and opens when the discharge pressure reaches a constant value, and the supercharging pressure is controlled by the slide amount. When a screw type compressor is used, the air-fuel mixture is internally compressed, so that, for example, when the engine is lightly loaded, a corresponding supercharging pressure can be obtained and efficiency is high.

[0005]

However, when the above-mentioned roots blower is used, when the air-fuel mixture 120 sent by the rotors 3 and 5 communicates with the discharge port 15 (see FIG. 3D), supercharging on the discharge side is performed. The air-fuel mixture having a pressure suddenly flows back into the casing 107 due to the pressure difference. This causes noise in the supercharger. In addition, since power is consumed extra to discharge the air-fuel mixture 120 against the reverse flow, there is a problem that efficiency is reduced.

Therefore, if the above slide valve used in the screw type compressor 201 is used to prevent backflow, the problem that the slide valve is complicated and expensive will remain.

The present invention has been made in view of these problems, and an object thereof is to provide a supercharger capable of preventing backflow of supercharged air by a valve having a simple and inexpensive structure.

[0008]

In order to solve the above problems, the present invention relates to a supercharger, which comprises a casing and a pair of rotors housed in the casing, and which is driven by an engine. It is characterized in that it has a plate-like check valve which is arranged in the vicinity of the discharge port and which opens and closes the discharge port by the pressure difference between the front and rear sides and blocks the reverse flow of the downstream supercharged air.

[0009]

According to the present invention, while the intake pressure at the discharge port of the supercharger is lower than the supercharging pressure downstream of the check valve, the check valve is in the closed position, and the supercharging air downstream of the check valve is Prevent backflow. When the intake pressure at the discharge port becomes higher than the supercharging pressure downstream of the check valve, the check valve opens and supercharging is performed.

[0010]

An embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic diagram showing the structure of a roots type supercharger. The supercharger 1 is arranged, for example, between the carburetor and the intake manifold (both not shown) as in the conventional example. In FIG. 1, the left side of the supercharger 1 is the suction side, and the right side is the discharge side.

In this embodiment, as shown in FIG.
Leaf rotors 3 and 5 are arranged in the casing 7 with their phases shifted, and are mechanically driven by the crankshaft of the engine via timing gears (not shown). The rotors 3 and 5 do not come into contact with each other with a small clearance maintained, and rotate in reverse with each other with the parallel two shafts 9 and 11 respectively. Reference numeral 13 is a suction port, and 15 is a discharge port.

The check valve 17 is arranged at the discharge port 15 in the discharge side passage 19 as shown in the drawing so as to cross it obliquely. The check valve 17 is made of a plate material having a predetermined thickness and has a discharge port 1
5 and the passage 19 are formed in a contour corresponding to the sectional shape. The pressure difference between the discharge port 15 and its downstream side allows swinging around the shaft 17b as a fulcrum, thereby opening and closing the discharge port 15. The illustrated closed position shows the state in which the discharge port 15 is closed by the higher pressure on the downstream side. At this time, the check valve tip portion 17a and the contour portion both come into contact with the lower end portion 19a of the discharge side passage 19 and the inner surface of the passage to close the discharge port 15. The check valve 17 can swing only to the right from the closed position with 17b as a fulcrum, and the discharge port 15 can be opened.

Next, the operation will be described.

The rotors 3 and 5 rotate in the opposite directions to each other in the directions of the rotation arrows in FIG. 1 to deliver the air-fuel mixture (for example, 20 in FIG. 1) between each and the casing 7 to the discharge port. The movement of the air-fuel mixture between suction and discharge is as described in the conventional example (see FIG. 3). Thus, the discharge is performed four times per rotation, but the internal compression of the air-fuel mixture between the suction and the discharge is not performed. While the pressure of the air-fuel mixture accumulated in the discharge port 15 is lower than the supercharging pressure downstream of the check valve 17, the check valve 1
Since 7 is pushed to the downstream side supercharged air and is in the closed position shown by the solid line in FIG. 1, the downstream side supercharged air does not flow back to the discharge port 15. When the discharge port pressure becomes higher than the downstream supercharging pressure, the check valve 17 swings to open the discharge port 15 as shown by the broken line in FIG. 1, for example. The valve opening pressure of the check valve 17 is not a constant value but changes according to the set value of the supercharging pressure on the downstream side.

The check valve 17 has a swing fulcrum 17b.
May be provided near the center of the substantially circular cross section of the discharge side passage 19 to form a so-called butterfly type, or may be a reed valve.

Thus, according to this embodiment, the check valve 17
Has a backflow prevention effect, unlike the above-described conventional example, when the air-fuel mixture 20 sent by the rotors 3, 5 communicates with the discharge port 15, the supercharged air having the supercharging pressure on the downstream side suddenly flows backward. It is possible to prevent the phenomenon. The check valve 17 formed of a plate material has a simple structure and is inexpensive.

[0018]

As is apparent from the above description, according to the present invention, a check valve formed of a plate material is provided in the vicinity of the discharge port of the supercharger, and the supercharging air downstream of the check valve is discharged. Since the backflow to the outlet is prevented, the noise of the supercharger due to the rapid backflow of the supercharging air can be reduced by the simple structure and inexpensive structure, which improves the efficiency.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration of a supercharger according to an embodiment.

FIG. 2 is a schematic diagram showing the configuration and arrangement of a conventional supercharger.

FIG. 3 is an explanatory diagram showing an operation of a conventional supercharger.

FIG. 4 is an explanatory diagram of another conventional screw compressor.

FIG. 5 is an explanatory diagram showing the operation of another conventional screw compressor.

[Explanation of symbols]

 3,5 rotor 7 casing 7b shaft 15 discharge port 17 check valve 19 passage

Claims (1)

[Claims] 1. A supercharger comprising a casing and a pair of rotors housed in the casing and driven by an engine. The supercharger is disposed in the vicinity of a discharge port of the supercharger, and the discharge due to a pressure difference between the front and the rear. A supercharger characterized by having a plate-like check valve that opens and closes an outlet and prevents a backflow of supercharged air on the downstream side.