JPH057466Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an engine equipped with a mechanical supercharger.

[Conventional technology]

Japanese Patent Application Laid-open No. 16232/1983 discloses an engine equipped with a mechanical supercharger. Some of the supercharger leaks from the end face of the rotor and hits the bearings. In this publication, in order to ensure the lubricant retention ability of the bearings of a supercharger, the supercharging pressure applied to the bearings is bled to the atmosphere, and a control valve is provided in the middle. Furthermore, the improvement proposal is published in Japanese Patent Application No. 60-270748 and Patent Application No. 7190-1983.
This is done in the No.

[Problem that the invention attempts to solve]

A mechanical supercharger is generally constituted by a positive displacement pump, and in the above-mentioned publication and the present invention, it is constituted by a Roots pump. A positive displacement pump produces periodic pulsations during its compression operation, and this pulsating pressure leaks from the end face of the rotor of the supercharger and is transmitted to the control valve described above. This control valve is opened and closed depending on the operating state of the engine, for example, it is closed when the engine is idling, and other than when the engine is idling, it is opened and closed depending on the supercharging state, acceleration state, etc. If the pulsating pressure of the supercharger acts on a closed control valve, it may open unexpectedly, leading to undesirable consequences.

[Means for solving problems]

The supercharged engine according to the present invention is an engine equipped with a mechanical supercharger configured with a Roots pump, in which the end face of the rotor of the supercharger and the support shaft of the rotor are supported within the casing of the supercharger. An air introduction passage is connected to an annular space formed around the support shaft, and a control valve that is operated depending on the operating state is disposed in the middle of the air introduction passage, and the control valve is connected to the bearing. and the annular space, the check valve allows flow from the annular space toward the control valve when the pressure in the annular space is lower than a predetermined pressure, and the check valve allows flow from the annular space toward the control valve when the pressure in the annular space is lower than the predetermined pressure. When the pressure is higher than a predetermined pressure, the flow from the annular space toward the control valve is prohibited, and the predetermined pressure is lower than the opening pressure of the control valve.

〔Example〕

In FIG. 1, reference numeral 10 denotes an engine body. As is well known, a piston (not shown) is inserted into the engine body 10 so as to be able to reciprocate, and the piston is connected to a 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 22 is formed by an intake pipe, an intake manifold, and an intake port, and includes an air cleaner 16 and an air flow meter 1 in order from the upstream side.
7, 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 an electromagnetic clutch attached to the support shaft of one rotor 22 is connected to a crank pulley by a timing belt. It is mechanically driven by the rotation of the crankshaft.

FIG. 2 is a detailed view of the supercharger 20, in which the rotor 22 is disposed within the casing 24, and the support shaft 26 of the rotor 22 extends through the end wall 24a of the casing 24, and the rotor 22 is disposed within the casing 24. It is supported by a bearing 28 in a hole wall formed by penetrating the part wall 24a. A lubricant is applied to the bearing 28, for example, a second
In the figure, the bearing 28 on the left side is a grease filled type, and the bearing 28 on the right side is a type filled with oil. Seal means 3 are provided inside these bearings 28.
0 is placed to prevent these lubricants from flowing towards the rotor 22. Also, each rotor 2
A gear 32 is attached to one end of the two support shafts 26, 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.

Further, 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 (i.e., its sole means 30), and these annular spaces 36 are open to the atmosphere. It is opened to the atmosphere through an introduction passage. That is, the atmosphere inlet passage consists of a port portion 38 passing through the casing 24 and a pipe portion 40 extending from the port portion to the atmosphere inlet;
As shown in FIG. 1, the atmosphere inlet is formed in the intake passage 12 upstream of the throttle valve 18.

As shown in FIG. 1, a control valve 42 is disposed in the atmosphere introduction passage 40, and the control valve 42
A check valve 44 is disposed between the annular space 36 in the supercharger 20 and the annular space 36 in the supercharger 20. The control valve 42 is the solenoid 4
The valve member 48 has a valve member 48 operated by a valve 6, and the valve member 48 is biased in the valve closing direction by a spring 50. A control device 52 is provided to control the operation of the control valve 42, and the control device 52 includes several sensors a, b,
c, d, e, for example, commonly used load sensors,
Detection signals from the rotation speed sensor, throttle position sensor, etc. are input. The valve member 48 is normally biased 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. Therefore, the control valve 42 is kept closed only by the spring 50, and if a large pressure is applied to the air introduction passage 40, the control valve 42 may be opened unexpectedly. The check valve 44 relieves the pulsating supercharging pressure of the supercharger 20 from being applied to the control valve 42, and is biased by a spring and can open toward the annular space 36 of the supercharger 20. It includes a valve member 54.

As schematically shown in FIG. 1, the supercharger 20 has an intake port and a discharge port at positions substantially opposed to each other in the circumferential direction of the casing 24, and performs a compression action twice per revolution of the rotor 22. A small clearance space between the end surface of the rotor 22 and the casing end wall 24a facing the rotor 22 communicates with both the suction port and the discharge port, and receives an intermediate pressure between the suction pressure and the supercharging pressure. At high load when the throttle valve 18 is fully open, the upstream side of the supercharger 20 is at approximately atmospheric pressure, and the downstream side thereof is at supercharging pressure. Therefore, at this time, it can be said that the bearing 28 receives a pressure that is half of the supercharging pressure. On the other hand, during partial load supercharging when the throttle valve 18 is throttled down to a certain extent, the supercharger 2
The upstream side of 0 becomes negative pressure, the downstream side thereof becomes supercharging pressure, and the pressure that the bearing 28 receives is smaller than half of the supercharging pressure. Therefore, the valve member 54 of the check valve 44 closes when it receives a pressure that is half of the supercharging pressure at high loads, but does not close at partial load pressures. Moreover, although the pressure that closes the check valve 44 is half the supercharging pressure at high loads, this does not mean the average pressure, but rather the pulsating supercharger discharge as shown in FIG. The closing pressure of the check valve 44 is lower than the opening pressure of the control valve 42 and close to the peak pressure of the pulsating pressure, as shown by v in FIG. be set accordingly. Therefore, even if the check valve 44 receives pressure in the valve-closing direction, it remains open for the most part, making it possible to bleed the supercharging pressure applied to the annular space 36 to the atmosphere. In addition, the check valve 44 tries to close in a pulsed manner only when it receives the peak of the pulsation of the discharge pressure of the supercharger 20, thereby absorbing the large peak pressure and reducing the pulsating pressure to a value close to its average value. This is no longer sufficient to cause the control valve 42 to open. As a result, the control valve 4
2 can be prevented from chattering due to direct exposure to pulsating supercharging pressure.

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.
It is opened at times other than idle to bleed the supercharging pressure applied to the annular space 36 to the atmosphere in order 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 is closed even when the engine is not idling. For example, the control valve 42 is closed for a predetermined period of time during sudden acceleration, or is closed in a low-speed supercharging region. At such times, a large boost pressure is applied from the atmospheric air introduction passage 40 to the control valve 42, attempting to open it. However, in the present invention, such large pulsating supercharging pressure is damped by the check valve 44, and the control valve 42 can be maintained in the closed state without making the spring 50 too large.

FIG. 3 shows a second embodiment of the present invention, in which a relief valve 56 and a spring 58 for biasing the relief valve 56 are provided in parallel with the valve member 54 in the check valve 44 of FIG. It is something. In this case, the valve port that cooperates with the relief valve 56 is a throttle passage, which can prevent large pressure from suddenly passing through. The valve member 54 also prevents passage of large pressure, and by providing these valve members in parallel, the pressure is reliably buffered.

As explained above, according to the present invention, it is possible to bleed the supercharging pressure applied to the annular space to the atmosphere, thereby reducing the pressure difference on both sides of the bearing, and also to reduce the peak of the supercharging pressure in the annular space. It is possible to prevent the control valve from malfunctioning and opening due to the pressure.

[Brief explanation of drawings]

Fig. 1 is a diagram showing a supercharged engine to which the present invention is applied, Fig. 2 is a sectional view showing details of the supercharger, Fig. 3 is a diagram showing a second embodiment of the present invention, Fig. 4 FIG. 2 is a diagram showing the pulsating discharge pressure of the supercharger. 20...Supercharger, 22...Rotor, 26...Rotor support shaft, 28...Bearing, 36...Annular space, 38, 40...Atmospheric introduction passage, 42...Control valve, 44...Check valve.

Claims (1)

[Scope of utility model registration request] 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, and a control valve that is operated depending on the operating condition is disposed in the middle of the air introduction passage, and a check valve is provided between the control valve and the annular space. and the check valve allows flow from the annular space toward the control valve when the pressure in the annular space is lower than the predetermined pressure, and when the pressure in the annular space is lower than the predetermined pressure. A supercharged engine characterized in that when the pressure is high, the flow from the annular space toward the control valve is prohibited, and the predetermined pressure is lower than the opening pressure of the control valve.