JPS62294720A - Supercharged engine - Google Patents

Abstract

PURPOSE:To prevent abrupt torque fluctuation, by retarding the switching action of a control valve which is disposed in an air intake passage. CONSTITUTION:On idling time, a negative pressure switching valve 44 is communicated with a black port so as to supply air for the diaphragm chamber 52 of a control valve 42. The valve disc 50 of the control valve 42 is closed, so that air intake for the annual space adjacent to the bearing of a mechanical supercharger 20 is interrupted. On operation condition except the idling time, the negative pressure switching valve 44 is switched to be communicated with a white port so as to supply negative pressure for the diaphragm chamber 52. The valve disc 50 is lifted, so that air is introduced to the annual space adjacent to the bearing of the supercharger 20. On switching time, a retarding device 64 which is disposed in a negative pressure passage 53 and a retarding device 66 which is disposed in an air passage 58 are respectively operated so as to shift the control valve 42 gradually from open condition to close condition or conversely.

Description

[Detailed description of the invention] :3, Detailed explanation of the invention [Industrial application field] The present invention relates to a supercharged engine.

[Conventional technology]

An engine equipped with a mechanical supercharger constituted by a Roots pump is described, for example, in Japanese Patent Laid-Open No. 16232/1983. Roots pumps include a pair of synchronously rotated rotors, each supported by a rotor shaft. The rotor shaft is attached to the housing by bearings. However, since the leakage pressure of the pump acts on this bearing, there is a problem in that its ability to retain oil and grease is reduced.
Japanese Patent No. 16232 introduces the atmosphere inside the bearing to equalize the pressure on both sides of the bearing. Air is introduced by a control valve depending on the operating state of the engine.

[Problem that the invention seeks to solve]

In the above-mentioned mechanical supercharger, the greater the amount of air introduced, the smaller the pressure difference on both sides of the bearing, and therefore the durability of the supercharger can be improved. However, introducing the atmosphere into the bearing means supplying air to the pump from the atmosphere introduction passage, a part of which is sucked into the engine.

When the control valve is controlled to the open side, air is instantaneously supplied to the bearing, and at the same time, the amount of air taken into the engine is instantaneously increased.

As the amount of air introduced increases, the amount of air taken into the engine increases, and if the amount of air increases rapidly, the torque generated by the engine fluctuates rapidly, resulting in a problem that drivability deteriorates.

Conversely, when the control valve is controlled to the closing side, the amount of air rapidly decreases, and the torque generated by the engine also fluctuates rapidly, deteriorating drivability.

[Means for solving problems]

In order to solve the above problems, a supercharged engine according to the present invention includes a roots pump that constitutes a mechanical supercharger, which includes a housing, a rotor disposed in the housing, and a bearing for supporting the rotor. The rotor shaft is attached to the housing by the rotor shaft, an air introduction passage that introduces the atmosphere into an annular space formed around the rotor shaft between the end face of the rotor and the bearing, and a control valve disposed in the air introduction passage. The control valve is equipped with a delay means that opens and closes the control valve in accordance with the operating state of the engine to adjust leakage pressure of the pump applied to the bearing, and delays switching operation when switching the control valve. A supercharged engine.

〔Example〕

1 and 2, 10 indicates an engine, and an intake passage 12 connected to the engine 10 includes, in order from the upstream side, an air cleaner 14, an air 70-meter 16, a throttle valve 18, and an R mechanical supercharger 20. The mechanical supercharging n20 in which the 0 mechanical supercharging n20 is arranged is constituted by a Roots pump having a pair of rotors 22.

As shown in FIG. 1, the rotor 22 of the mechanical supercharger 20 has a bilobal cross-sectional shape, and it is known that the rotor 22 performs a pumping action by rotating in opposite directions in synchronization with each other. It is. These rotors 22 engage with each other with a minute clearance, and each rotor 22 contacts the housing 24 with a minute clearance. The housing 24 includes an end plate 24a, and the end face of each rotor 22 is connected to the housing 2 with a minute clearance.
It also comes into contact with the end plate 24a of No. 4. Therefore, the clearance space between the end surface of the rotor 22 and the end plate 24a communicates with the suction side and the discharge side of the pump, and leakage pressure of the pump is generated there.

Each rotor 22 is supported by a rotor shaft 26, respectively. The rotor shaft 26 extends within a hole formed in the end plate 24a, and has a bearing 2 at each end.
8 is attached to the end plate 24a. In order to alleviate the aforementioned leakage pressure applied to the bearing 28, a labyrinth seal is formed at a relatively inner diameter portion between the end surface of the rotor 22 and the opposing end surface of the end plate 24a. Furthermore, a seal 3 is provided inside each bearing 28.
0 is placed. The right end of each rotor shaft 26 in FIG. 2 protrudes from the bearing 28, and a gear 32 meshing with the protruding end is attached to the rotor shaft 26 so that the pair of rotors 22 can rotate in opposite directions. An electromagnetic clutch 34 is attached to the left end of the lower rotor shaft 26, so that the mechanical supercharger 20 can be driven from the crankshaft of the engine 10.

An oil chamber 32a is formed to lubricate the gear 32, and the right bearing 28 is lubricated by this oil. On the other hand, the left bearing 28 is filled with grease.

As shown in FIG. 2, the end plate 24a of the housing 24 has a hole for passing the rotor shaft 26, and the hole is located between the end face of the rotor 22 and the inner seal 30 of the bearing 28. An annular space 36 is formed around 26. In order to introduce the atmosphere into this annular space 36, a radially extending boat 38 is formed on the end plate 24a of the housing 24, and this boat 38 also extends between the two rotor shafts. A control valve (AC) 42 is disposed in the middle of a conduit 40 connecting the atmosphere and the boat 38.

As shown in FIG. 1, the control valve 42 is a valve operated by negative pressure, and the operating negative pressure is a negative pressure switching valve (VSV).
) 44, and the negative pressure switching valve 44 is controlled by an electronic control unit (ECU) 46. control valve 42
has a valve body 50 attached to the diaphragm 48,
Diaphragm chamber 5 formed on one side of diaphragm 48
2 is connected to a negative pressure boat 54 of the intake passage 12 downstream of the throttle valve 18 via a negative pressure passage 53 attached to the negative pressure switching valve 44#. A spring 56 is arranged within the diaphragm chamber 52 to bias the diaphragm 48 against negative pressure. The source of atmospheric air introduction is the intake passage 12 upstream of the throttle valve 18.

The negative pressure switching valve 44 is a solenoid valve with two positions, and when the white boat is connected, negative pressure is supplied to the control valve 42 via the negative pressure passage 53, and when the black boat is connected, the negative pressure is supplied to the control valve 42 through the atmospheric passage. Atmospheric air is supplied via 58. Atmospheric passage 5
8 is connected to the intake passage 12 upstream of the throttle valve 18, and a delay device 60 with a throttle is disposed in the middle thereof.

Further, a check valve 62 and a delay device 64 having a throttle are arranged in the negative pressure passage 53. In the embodiment, the apertures of delay device 60 and delay device 64 have different dimensions, which can be changed as desired. The check valve 62 is connected to the intake passage 12 downstream of the throttle valve 18.
This is to take in the negative pressure into the diaphragm chamber 52 while the negative pressure in the intake passage 12 is large, and to maintain the negative pressure when it is large even if the negative pressure in the intake passage 12 becomes small.

Next, the operation will be explained.

The mechanical supercharger R20 is driven by the engine and supplies a large amount of air to the engine. At this time, mechanical supercharger 2
There is leakage pressure generated by the suction pressure and discharge pressure of the pump in the clearance space between the end surface of the rotor 22 and the end plate 24a. Since this leakage pressure acts on the inside of the bearing 28 and tries to push out the oil and grease, the oil and grease are prevented from being pushed out by introducing atmospheric air from the atmosphere passageway 40 and the control valve 42. be. However, as mentioned above, introducing atmospheric air means supplying the engine with an amount of air greater than that controlled by the throttle valve 18, and since it is undesirable to supply uncontrolled air during idle, for example, the electronic control The negative pressure switching valve 44 is switched according to a command from the device 46, and the black boat is connected to supply atmospheric air to the diaphragm chamber 52 of the control valve. The valve body 50 of the control valve 42 then engages the corresponding valve seat and interrupts the introduction of atmospheric air into the annular space 36 next to the bearing 28 of the mechanical supercharger. This eliminates the supply of excess air during idle, making it possible to obtain the set idle speed. Furthermore, at idle, the rotation of the engine and supercharger 20 is not high, and the pressure applied to the bearing 28 is not very high.
Even if the introduction of atmospheric air into the annular space 36 adjacent to the bearing 28 is interrupted, the durability of the bearing 28 is not significantly affected.

When the operating state is other than idle, the negative pressure switching valve 44
is switched, bringing the white boat into communication and supplying negative pressure to the diaphragm chamber 52 of the control valve 42. The negative pressure lifts the valve body 50 and introduces atmospheric air into the annular space 36 next to the bearing 28 of the supercharger. As a result, leakage air from the supercharger is prevented from being applied to the bearing 28, and the bearing 28 is
durability is improved.

As explained above, the control valve 42 is switched depending on the operating state of the internal combustion engine. At the time of switching, a delay device 64 disposed in the negative pressure passage 53 and a delay device 60 disposed in the atmospheric passage 58 are respectively operated to gradually change the control valve 42 from the open state to the closed state B'\, or Control valve 12 is gradually switched from a closed state to an open state, thus delaying the switching operation of control valve 42. The method of delay is determined by the respective delay devices 60 and 6.
It is determined by the size of the aperture of 6. By delaying the switching operation of the control valve 42, the supercharger bearing 28
The atmosphere introduced into the annular space 36 next to
As a result, the amount of air drawn from the annular space 36 along the end surfaces of the lohita 22 and the end plate changes slowly. Thereby, sudden torque fluctuations can be prevented.

FIG. 3 shows a second embodiment of the present invention. In the first embodiment, delay devices 60 and 64 are disposed in the negative pressure passage 53 and the atmospheric passage 58, respectively, to delay the opening operation of the control valve 42. Whereas there was a difference in the delay effect during the opening operation, in the second embodiment, one delay device 70 is provided between the control valve 42 and the negative pressure switching valve 44, and the delay effect during the opening operation of the control valve 42 is The delay effect during the closing operation is made to be the same as the delay effect during the closing operation. FIG. 4 shows a third embodiment of the present invention, in which the delay device 60 of the atmospheric passage 58 of FIG. 1 is omitted and the negative pressure passage 58 is
A delay device 64 is provided only in the second embodiment.

FIG. 5 shows a fourth embodiment of the present invention, in which the delay device 64 in the negative pressure passage 53 of FIG. 1 is omitted and a delay device 60 is provided only in the atmospheric passage 58. Furthermore, although an example in which the control valve is operated by negative pressure has been described above, an electrically operated valve may also be used, and in this case, an electrical delay means is provided.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to increase the durability of a supercharger, and to reduce torque fluctuations caused by introducing atmospheric air into the bearings of the supercharger.

[Brief explanation of the drawings] Fig. 1 is a configuration diagram of a supercharged engine according to the present invention, Fig. 2
The figure is a cross-sectional view of the supercharger shown in FIG. 1, FIG. 3 is a view showing a second embodiment of the present invention, and FIG. 4 is a view showing a third embodiment of the present invention.
FIG. 5 is a diagram showing a fourth embodiment of the present invention. 20...Supercharger, 22...Rotor, 2
6... Rotor shaft, 28... Bearing, 38...
...Atmospheric introduction passage, 42...Control valve, 44...
-Negative pressure switching valve, 60, 64...delay device. 20...Supercharger 22...Rotor 28...Bearing 38, - Atmospheric introduction passage 42...Control valve 60.64...Delay device Fig. 2 Fig. 311

Claims (1)

[Claims] In an engine equipped with a mechanical supercharger configured with a Roots pump, the Roots pump includes a housing;
a rotor disposed within the housing; a rotor shaft attached to the housing by a bearing to support the rotor; and an annular ring formed around the rotor shaft between an end surface of the rotor and the bearing. It is equipped with an air introduction passage for introducing air into the space and a control valve disposed in the air introduction passage, and the control valve is opened and closed according to the operating state of the engine to adjust the leakage pressure of the pump applied to the bearing. and a supercharged engine, further comprising a delay means for delaying a switching operation when switching the control valve.