JPH06280584A - Inner compression ratio variable mechanism for supercharger - Google Patents

Abstract

PURPOSE:To surely remove oil content from the atmospheric pressure chamber of a diaphragm connected to a piston changing the discharge port area of a screw type pump. CONSTITUTION:In an inner compression ratio variable mechanism, a piston holder is fitted in a stepped piston inserting hole formed on the side of a rotor housing, the connecting rod part of a piston is slidably insertedly fitted to the piston holder, the piston capable of being advanced and retreated in the direction meeting at nearly right angles with the axial direction of a gate rotor is held, and a diaphragm is connected to the connecting rod of the piston. A breather hole communicating to the atmospheric pressure chamber of the diaphragm is provided, and the breather hole is communicated to the bypass passage of an intake system through a rubber tube and the like.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable internal compression ratio mechanism for a supercharger.

[0002]

2. Description of the Related Art As a conventional internal compression ratio variable mechanism of a supercharger to which a screw type pump is applied, there is disclosed in Japanese Patent Laid-Open No. 4-1754.
The one disclosed in Japanese Patent Publication No. 95 is known. This will be described with reference to FIG. 6. The main rotor 102 and the sub-rotor 10 that mesh with each other in the pump housing 101.
3 is rotatably supported, and a piston 105 for changing the discharge port volume is held in a piston holder 104 attached to the pump housing 101 so as to be able to move back and forth.

Then, the piston holder 104 and the case 1
And the peripheral edge of the diaphragm 107 is sandwiched between the diaphragm 107 and the control chamber 106 to define an atmospheric pressure chamber 108 and a control pressure chamber 109. The rear end of the connecting rod 105a of the piston 105 is connected to the diaphragm 107. Diaphragm 107 inside
Is provided with a spring 110 for urging the control pressure chamber 109 side, that is, the piston 105 toward the low compression position side. Further, a key 111 having a rectangular cross section for preventing rotation of the piston 105 is attached to the pump housing 101 with a screw 112.

[0004]

By the way, in the internal compression ratio variable mechanism of the supercharger as described above, air is sucked from the rotor chamber to the atmospheric pressure chamber of the diaphragm through the outer peripheral surface of the piston and the outer peripheral surface of the connecting rod of the piston. A liquid substance such as oil contained in the blow-by gas of the engine contained in the air may enter and stay in the atmospheric pressure chamber to generate a reaction force when the diaphragm operates.

In particular, when a communication hole is formed in the piston to connect the back pressure chamber formed between the piston holder and the piston to the discharge port, intake air is introduced from the rotor chamber into the back pressure chamber through the communication hole. Since it directly flows in, the liquid substance easily enters the atmospheric pressure chamber, so that the liquid substance is likely to stay in the atmospheric pressure chamber and generate a reaction force when the diaphragm operates.

[0006]

In order to solve the above-mentioned problems, the present invention is directed to a supercharger which employs a screw type pump having a variable internal compression ratio by a piston movable in a direction substantially orthogonal to the axis of a rotor. In the machine, a breather hole for discharging a liquid substance is provided in an atmospheric pressure chamber defined by a diaphragm that moves the piston forward and backward. Further, according to the present invention, the breather hole is connected to the engine intake passage. Further, according to the present invention, the breather hole is connected with a pipe line having a volume at least larger than the discharge air volume at the maximum operation of the diaphragm.

[0007]

[Function] By installing a breather hole facing the atmospheric pressure chamber of the diaphragm at the lowest position when the supercharger is mounted on the vehicle, the liquid substance staying in the atmospheric pressure chamber is discharged to the outside through the breather hole. it can. Also, by connecting the breather hole to the engine intake passage, it is possible to prevent liquid substances from adhering to the periphery of the breather hole and blocking the breather hole, and also to prevent foreign matter from entering the atmospheric pressure chamber from the outside through the breather hole. You can prevent intrusion. Further, even if the breather hole cannot be connected to the intake passage of the engine by connecting the breather hole with a pipe line having a volume larger than the discharge air volume at the maximum operation of the diaphragm, even if the breather hole cannot be connected to the intake passage of the engine, the outside environment is It is possible to prevent air containing foreign matter from flowing into the atmospheric pressure chamber.

[0008]

Embodiments of the present invention will be described below with reference to the accompanying drawings. Here, FIG. 1 is a system diagram of a vehicle to which the supercharger according to the present invention is applied, and FIG. 2 is a cutaway vertical sectional view of the supercharger.
3 is a side sectional view taken along the line AA of FIG. 2, FIG. 4 is a plan view of an internal compression ratio variable mechanism portion of the turbocharger, and FIG. 5 is a bottom view of a main portion of the internal compression ratio variable mechanism portion. is there.

As shown in FIG. 1, the engine body (engine)
An intake passage 2 and an exhaust passage 3 are connected to 1, and an air cleaner 4 is connected to an upstream end of the intake passage 2. Further, a mechanical supercharger (supercharger) 5, to which a screw pump is applied, an intercooler 6 and a throttle valve 7 are provided in the middle of the intake passage 2 in that order from the upstream side, and the supercharger 5 and the intercharger 5 are installed. A bypass passage 8 that bypasses the cooler 6 is provided, and a bypass valve 9 is interposed in the bypass passage 8. A blow-by passage 10 is provided between the engine body 1 and the upstream side of the throttle valve 7.
Is provided.

As shown in FIGS. 2 to 4, the supercharger 5 rotatably supports a pair of intermeshing main rotors 12 and gate rotors 13 in a pump housing 11, and a crankshaft 1a of the engine body 1 ( The suction port 14a (not shown) on one axial side of the housing 11 is provided by both rotors 12 and 13 that are driven to rotate by receiving power from FIG.
The air sucked from is compressed and discharged from the discharge port (discharge port) 14b at the other end in the axial direction.

The pump housing 11 comprises a rotor housing 15 which is a cylindrical member with a bottom closed at one end, and an end wall member 16 which is bonded so as to cover the open end of the rotor housing 15. The inside of 15 is formed as a rotor chamber 17 in a cross-sectional shape corresponding to the rotation locus drawn by the radially outer ends of both rotors 12 and 13, and has an inner surface that is not in contact with both rotors 12 and 13 and has closed ends. The suction port is formed in the part. Both rotors 12, 1
Reference numeral 3 is a rotor housing 1 with rotating shafts 18 and 19, respectively.
5 is rotatably arranged in the rotor chamber 17 inside.

An internal compression ratio changing mechanism 20 for changing the internal compression ratio is provided on the side of the rotor housing 15 of the pump housing 11. This internal compression ratio variable mechanism 2
In No. 0, a part of the piston holder 22 is fitted in the stepped piston insertion hole 21 formed on the side portion of the rotor housing 15 and mounted, and the connecting rod portion 25 of the piston 24 is inserted into the piston holder 22 via the bearing sleeve 23. Is slidably inserted to hold a piston 24 that can advance and retreat in a direction substantially orthogonal to the axial direction of the gate rotor 13.

The piston 24 can advance and retreat between a high internal compression ratio position protruding toward the rotor chamber 17 and a low internal compression ratio position moved in the retracting direction from the rotor chamber 17, and at the high internal compression ratio position, The cylindrical surface of the tip of the piston 24 on the rotor chamber side is integrated with the inner peripheral surface of the rotor housing 15 and maintains a small clearance with the outer periphery of the gate rotor 13 to perform pneumatic outer peripheral sealing of each groove of the rotor 13.

Here, a flange portion 26 is formed on the outermost peripheral portion of the piston 24, and a seating surface 26a which is an end surface of the flange portion 26 on the rotor chamber 17 side is formed in the piston insertion hole 21 of the rotor housing 15. By abutting against the portion 21a, the position of the high internal compression ratio position of the piston 24 is regulated.

Further, as described above, a part of the piston holder 22 is fitted into the piston insertion hole 21 to regulate the position of the piston holder 22, and the outer periphery of the connecting rod portion 25 of the piston 24 and the central portion of the piston holder 22. The piston 24 is positionally regulated with respect to the piston holder 22 by a spigot fitting in a hole provided through the bearing sleeve 23 in the longitudinal direction (axial direction of the rotor 13) of the rotor chamber 17 of the piston 24. The position is regulated in a direction on a line passing through the centers of the main rotor 12 and the gate rotor 13.

Further, a knock pin (not shown) is provided between the piston holder 22 and the rotor housing 15 to regulate the position of the piston holder 22 with respect to the rotor housing 15. A key 28 having a circular cross-section protruding toward the piston 24 is press-fitted into the piston holder 22 at a portion of the collar portion 26 of the piston 24 where the seating surface 26b on the low internal compression ratio side abuts. It is fitted into a key hole 24a (see FIG. 5) formed in the collar portion 26 of the above, and the rotational direction position of the piston 24 with respect to the piston holder 22 is regulated to determine the rotational direction position with respect to the rotor housing 15.

Then, in order to drive the piston 24,
A case 30 is attached to the outer surface of the piston holder 22, and a diaphragm 31 is sandwiched between the piston holder 24 and the case 30 to define an atmospheric pressure chamber 32 and a control pressure chamber 33. The diaphragm 31 has lower diaphragms on both sides. The plate 34 and the upper diaphragm plate 35 are connected to the connecting rod 25 of the piston 24 by bolts 36. The piston holder 24 is provided on the atmospheric pressure chamber 32 side.
A return spring 37 for urging the piston 24 toward the low internal compression ratio position (position shown in the drawing) is provided between the diaphragm 31 and the diaphragm 31.

As shown in FIG. 4, the return spring 37 has hooks 38 and 39 formed at both ends thereof, and the hook 38 on the side abutting the piston holder 22 is engaged with a projection 40 formed integrally with the piston holder 22. The hook 39 on the side that comes into contact with the diaphragm 31 is locked to a protrusion 41 that is integrally formed with the lower diaphragm plate 34.

The diaphragm 31 is attached to the piston 24.
When connecting to the connecting rod 25, the return spring 37 is rotated through the protrusion 40 of the piston holder 22 in a direction in which the number of turns of the spring increases (clockwise direction in FIG. 4) by a certain angle, and then the diaphragm 31 is connected. Rod 2
5, the piston 24 is set in a state in which a constant extra rotation torque is applied in the direction opposite to the spring winding direction (counterclockwise direction in FIG. 4), and the key hole 24a of the piston 24 is pressed against the key 28. I am trying to get into the state of being.

Returning to FIG. 1, the conduit 51 is branched from the intake passage 2 at a portion corresponding to the merging position of the bypass passage 8 on the downstream side of the intercooler 6, while the conduit is provided to the control pressure chamber 33 of the diaphragm 31. 52 (see FIG. 3) is connected to the passage 54 and the conduit 51, which are open to the atmosphere through the air cleaner 53, and the conduit 52. 55.

When the switching valve 55 is excited, the passage 5
4 is communicated with the conduit 52 to bring the atmospheric pressure into the control pressure chamber 33 of the internal compression ratio variable mechanism 20, and when demagnetized, the conduit 51 is communicated with the conduit 52 and the internal compression ratio variable mechanism 20 of the internal compression ratio variable mechanism 20. This is an electromagnetic switching valve in which the discharge pressure P2 is introduced into the control pressure chamber 33.

The switching valve 55 and the bypass valve driving means 56 for opening / closing the bypass valve 9 in the bypass passage 8 are drive-controlled by a control unit 57 including a microcomputer. The control unit 57 includes a rotation speed sensor 58 for detecting the engine speed of the engine body 1, a throttle opening sensor 59 for detecting the opening of the throttle valve 7, and a supercharging pressure for detecting a supercharging pressure attached to the conduit 51. Detection signals from the pressure sensor 60, the bypass valve opening sensor 61 that detects the opening of the bypass valve 9, and the like are input, and the switching valve 55 and the bypass valve driving means 56 are driven and controlled based on these input information. To do.

Referring again to FIGS. 2 to 4, the piston holder 22 of the internal compression ratio variable mechanism 20 is located at the lowest point when the vehicle is mounted on the piston holder 22 and is located in the atmospheric pressure chamber 32 of the diaphragm 31.
The breather hole 63 communicating with the
3, one end of the pipe joint 64 is press-fitted and connected,
A rubber hose 65 is connected to the other end of the pipe joint 64.

The other end of the rubber hose 65 is connected to the air cleaner 4-bypass valve 9 in the bypass passage 8 through a pipe joint (not shown) as shown in FIG. When a throttle valve is provided upstream of the intake system of the supercharger and the supercharging pressure is controlled by the throttle valve, it is connected between the air cleaner and the throttle valve.
The piston 24 has a communication hole 6 for communicating a back pressure chamber 67 formed between the piston 24 and the rotor holder 17 with the rotor holder 17.
8 forming.

In the internal compression ratio variable mechanism 20 constructed as described above, the breather hole 63 communicating with the atmospheric pressure chamber 32 of the diaphragm 31 is formed in the piston holder 22.
Since the breather hole 63 is communicated with the air cleaner 4-bypass valve 9 in the bypass passage 8 via the rubber hose 65 and the like, the air chamber (bypass which is almost equal to the atmospheric pressure (bypass) regardless of the operating conditions of the engine 1 is used. Passage) and atmospheric pressure chamber 3
2 is in communication with each other, the pressure change in the same chamber due to the change in the atmospheric pressure chamber volume during the operation of the diaphragm 31 does not occur, and the diaphragm 3
The operation of 1 is not suppressed.

Further, even if oil or the like in the blow-by gas of the engine enters the atmospheric pressure chamber 32 from the rotor chamber 17 through the communication hole 68 of the piston 24 and the outer peripheral portion of the connecting rod 25, the oil or the like is bypassed by the bypass passage 8. The foreign matter from the outside enters the atmospheric pressure chamber 32 through the breather hole 63 and prevents the piston 24 from sliding. Will disappear.

For the convenience of the layout, when the engine intake system is located above the internal compression ratio variable mechanism section 20 in a vehicle mounted state, the rubber hose 65 connected to the breather hole 63 is gradually extended downward. Route and install the open end in the vehicle's engine room away from the high temperature heat source.

At this time, the length of the rubber hose 65 is set so that the rubber hose 65 has a volume at least larger than the discharge air volume at the maximum operation of the diaphragm 31, so that the atmospheric pressure chamber 32 is kept outside. Although not completely isolated, the atmospheric pressure chamber 32 does not allow air containing dust and the like to directly flow into the atmospheric pressure chamber 32 due to breathing, so that the breather hole 63 is kept in a good state and the piston 24 caused by foreign matter is used. No longer interferes with the sliding.

[0029]

As described above, according to the present invention, since the breather hole facing the atmospheric pressure chamber of the diaphragm is provided in the lowermost portion when the supercharger is mounted on the vehicle, the breather hole is provided. As a result, the liquid substance staying in the atmospheric pressure chamber can be discharged to the outside, and the operation of the diaphragm can be prevented from being hindered. Also, by connecting the breather hole to the engine intake passage, it is possible to prevent the liquid substance that has entered the atmospheric pressure chamber from adhering to the periphery of the breather hole and blocking the breather hole, and also from the outside through the breather hole. It is possible to prevent foreign matter from entering the atmospheric pressure chamber and obstructing the sliding of the piston. Furthermore, even if the breather hole cannot be connected to the intake passage of the engine by connecting the breather hole with a pipe line having a volume larger than the discharge air volume at the maximum operation of the diaphragm, even if the breather hole cannot be connected to the intake passage of the engine, the external environment is Air containing foreign matter flows into the atmospheric pressure chamber from
It is possible to prevent the sliding of the piston from being hindered.

[Brief description of drawings]

FIG. 1 is a system diagram of a vehicle in which a supercharger according to the present invention is applied to the supercharger.

FIG. 2 is a cutaway sectional view of the turbocharger.

FIG. 3 is a side sectional view taken along the line AA of FIG.

FIG. 4 is a plan view of a variable internal compression ratio mechanism of the turbocharger.

FIG. 5 is a bottom view of a main part of the internal compression ratio variable mechanism section.

FIG. 6 is a cutaway sectional view in which a conventional supercharger is applied to the supercharger.

[Explanation of symbols]

1 ... Engine main body, 5 ... Supercharger, 8 ... Bypass passage, 11 ...
Pump housing, 12 ... Main rotor, 13 ... Gate rotor, 15 ... Rotor housing, 17 ... Rotor chamber, 2
0 ... Internal compression ratio variable mechanism, 22 ... Piston holder, 24
... Piston, 31 ... Diaphragm, 32 ... Atmospheric pressure chamber, 3
7 ... Return spring, 63 ... Breather hole, 65 ... Rubber tube.

Claims (3)

[Claims] 1. A supercharger having a main rotor and a gate rotor meshing with each other in a housing, and a piston provided at a discharge port for varying an internal compression ratio, wherein the piston advances and retreats with a diaphragm. Confused,
A variable internal compression ratio mechanism for the supercharger, characterized in that a breather hole is provided in the lowermost part of the atmospheric pressure chamber of this diaphragm when the supercharger is mounted on the vehicle. 2. The variable internal compression ratio mechanism for a supercharger according to claim 1, wherein the breather hole is connected to an engine intake passage. 3. The internal compression of the supercharger according to claim 1, wherein the breather hole is connected to a pipe line having a volume at least larger than a discharge air volume at maximum operation of the diaphragm. Variable ratio mechanism.