JPH0318661Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The invention provides a mechanical supercharger downstream of the throttle valve in the intake system of the engine, and a bypass control valve in a passage that bypasses the mechanical supercharger. Regarding the installed internal combustion engine.

[Conventional technology]

JP-A-58-15719 discloses a system in which a mechanical supercharger is provided upstream of a throttle valve, and a bypass control valve is provided in a bypass passage that bypasses the mechanical supercharger. The mechanical supercharger is selectively activated by a clutch. Furthermore, a diaphragm mechanism for driving the bypass control valve and a three-way switching valve for controlling introduction of control pressure to the diaphragm mechanism are provided. The diaphragm mechanism includes a diaphragm connected to the bypass control valve and a spring that biases the diaphragm to open the bypass control valve. The diaphragm chamber on the spring side is connected to the intake pipe downstream of the throttle valve via a check valve. The three-way switching valve operates to switch between a position where the diaphragm chamber on the opposite side of the spring communicates with the diaphragm chamber on the spring side and a position where the diaphragm chamber communicates with the intake pipe downstream of the bypass control valve and upstream of the throttle valve. A restriction is also arranged in the actuation pressure passage to the diaphragm chamber opposite the spring.

During non-supercharging operation when the clutch is released, the three-way switching valve is positioned so that the upper and lower diaphragm chambers communicate with each other, and at this time, intake pipe negative pressure is introduced into the upper and lower diaphragm chambers, so the pressures are balanced. A spring causes the bypass control valve to open.

During supercharging operation when the clutch is engaged, the three-way switching valve communicates the diaphragm chamber opposite the spring with the intake pipe downstream of the bypass control valve and upstream of the throttle valve. Therefore, supercharging pressure is introduced into the diaphragm chamber on the opposite side of the spring, and only the diaphragm chamber on the spring side becomes negative pressure, so the diaphragm deforms against the spring and closes the bypass control valve.

In addition, when the bypass control valve is switched from open to closed, the throttle installed in the operating pressure passage to the diaphragm chamber on the opposite side of the spring gradually closes the bypass control valve by gradually introducing boost pressure. to prevent acceleration shock from occurring. Further, since negative pressure is gradually introduced when the bypass control valve is switched from closed to open, the bypass control valve is also gradually opened.

[The problem that the idea attempts to solve]

JP-A No. 58-15719 has a supercharger installed upstream of the throttle valve, but there is also a model with a supercharger installed downstream of the throttle valve as a noise countermeasure. Even in such a supercharging device, when the clutch is switched from open to engaged (that is, when transitioning to supercharging operation), the operating speed of the bypass control valve is reduced to reduce shock in accordance with Japanese Patent Application Laid-open No. 15719/1983. It is necessary to. JP-A-58-15719 If left as is, the bypass control valve will slowly close and open due to the throttle function even when returning to non-supercharging operation. However, in a supercharging system in which a supercharger is provided downstream of a throttle valve, there is a problem in that when the bypass is gradually closed, the temperature of the intake air increases. The reason is as follows. Even if the throttle valve is closed and the clutch is disengaged, the supercharger continues to rotate at high speed for a while due to inertia. At this time, the bypass control valve does not open immediately due to the action of the throttle, and the upstream throttle valve is closed, so the inlet side of the supercharger becomes negative pressure, and the intake air amount of the supercharger is small, resulting in The temperature of the air increases. In addition, in the system of JP-A-58-15719, the supercharger is located upstream of the throttle valve, so the pressure on the inlet side of the supercharger is atmospheric pressure, and the intake air amount of the supercharger decreases during deceleration. Without a doubt,
Intake air temperature is maintained appropriately.

The purpose of this invention is to improve suction at the transitional point of transition from a supercharger to a non-supercharger without generating a supercharging shock in a mechanical supercharger with a supercharger installed downstream of the throttle valve. The purpose is to prevent the air temperature from rising.

[Means to solve the problem]

According to this invention, a mechanical supercharger connected to the engine drive shaft via a clutch means is provided downstream of the throttle valve in the intake system of the engine, and the supercharger is bypassed. In a mechanically supercharged internal combustion engine in which a bypass control valve is arranged in a passage connecting downstream of a throttle valve and upstream of a supercharger,
A bypass control valve includes a valve body disposed in a bypass passage, a diaphragm connected to the valve body, a negative pressure chamber formed on the side of the diaphragm on the opposite side of the valve body, and a valve body that normally connects to the bypass passage. The negative pressure chamber is normally connected to the negative pressure port downstream of the throttle valve of the intake system, but the negative pressure chamber is switched to communicate with the atmosphere by a control signal. A switching valve is provided, and a throttle is provided on the atmospheric side from the switching valve to control the transmission speed of atmospheric pressure to the negative pressure chamber, and on the negative pressure side from the switching valve, a throttle is provided for controlling the transmission speed of the negative pressure to the negative pressure chamber. There is no throttle to control the clutch means, and the switching valve is moved to a position where the negative pressure chamber connects to the negative pressure port and the negative pressure chamber communicates with the atmosphere by detecting the switching point between the opening and the engagement of the clutch means. The bypass control valve is gradually closed by introducing atmospheric pressure through a throttle when the clutch means is switched from open to engaged, and the bypass control valve is gradually closed when the clutch means is switched from open to engaged. Provided is a mechanically supercharged internal combustion engine characterized in that negative pressure is introduced without passing through a throttle when switching from close to open, so that the bypass control valve is immediately opened.

[Effect]

During non-supercharging, the switching valve is demagnetized and negative pressure is applied to the negative pressure chamber of the bypass control valve, so the bypass passage is open.

When supercharging operation starts and the clutch means is engaged,
The switching valve is energized, and atmospheric air is introduced from the air filter through the throttle into the negative pressure chamber. Initially, negative pressure remains in the negative pressure chamber and the bypass control valve remains open.

When the time determined by the orifice size comes, the valve body closes the bypass passage using the spring, and supercharging is performed.

The negative pressure is introduced immediately when switching from the supercharging region to the non-supercharging region without passing through the throttle, and the bypass control valve is opened rapidly.

〔Example〕

In FIG. 1, 10 is the engine body;
Piston 12, connecting rod 14, crankshaft 16, intake port 18, exhaust port 20,
It consists of components such as an intake valve 22 and an exhaust valve 24.
The intake port 18 is connected to an intake pipe 26, a throttle valve 28 is provided in the intake pipe 26, and an air flow meter 30 is provided upstream of the throttle valve 28.
An air cleaner 32 is located upstream thereof.

In this example, the internal combustion engine is fuel-injected;
A fuel injection valve 33 is provided within the intake pipe 26.

A mechanical supercharger 34 is arranged in the intake pipe 26 downstream of the throttle valve 28 . The purpose of providing a mechanical supercharger downstream of the throttle valve 28 is to reduce noise. That is, when the mechanical supercharger operates, airflow is transmitted upstream through the bypass passage 44, but the throttle valve 28 suppresses noise by blocking this transmission. The mechanical supercharger 34 includes a clutch 36, which
is connected to the crankshaft 1 via the pulley 38 and belt 40.
It is connected to a pulley 42 on 6. By this,
The engine drives the supercharger.

A bypass passage 44 is provided to bypass the mechanical supercharger 34, and a diaphragm type bypass control valve 80 is provided in the bypass passage 44.

48 is an electromagnetic three-way switching valve 8 for driving the clutch 36 and bypass control valve 80 of the mechanical supercharger.
6 control circuit and is configured as a microcomputer. The control circuit 48 is connected to engine operating condition detection sensors such as a throttle sensor 52 and an engine speed sensor 54, and as is well known, switches the drive of the clutch 36 and the bypass control valve 80 according to the engine operating conditions. It generates an actuation signal for valve 86 and operates to engage clutch 36 and close bypass control valve 80 when the engine is under high load and high engine speed. The bypass control valve 80 includes a valve body 801 and a valve stem 8.
02, a diaphragm 803, and a spring 804, further forming a negative pressure chamber 805. There is a negative pressure port 82 downstream of the throttle valve 28, and negative pressure is selectively introduced into the negative pressure chamber 805 via a check valve 84 and a switching valve 86. When the electromagnetic three-way switching valve 86 is de-energized, it assumes the white port position, and the negative pressure chamber 8
05 is communicated with the negative pressure port 82. On the other hand, when energized, the black port position is used and the negative pressure chamber 805 is at the throttle 8.
8 to the atmosphere or air filter 90 . In the operation of this embodiment, the throttle opening TA is determined by the signal from the throttle sensor 52 to the set value TA _x
When the load is smaller and lighter, the control circuit 48 is connected to the clutch 3.
6 is output, the rotation of the crankshaft 16 is not transmitted to the mechanical supercharger 34, and supercharging is not performed.
This signal is also transmitted to the switching valve 86, which is set to the white port position. During operation with a small throttle valve opening, a large negative pressure is generated in the port 82, so this negative pressure is introduced into the negative pressure chamber 805 via the check valve 84, and the diaphragm 803 is pulled against the spring 804. The stretched valve body 801 opens and the bypass passage 44 is opened. At this time, the check valve 84 maintains the negative pressure in the negative pressure chamber 805 above a certain value depending on the valve opening pressure. Negative pressure chamber 805 from port 82
Since there is no restriction in the negative pressure path, negative pressure is introduced immediately when the switching valve 86 is switched from ON to OFF.

When the throttle opening TA is higher than the set value TA _x and the load is high, an engagement signal for the clutch 36 is output from the control circuit 48 and is applied to the switching valve 86 at the same time as the mechanical supercharger 34 starts operating. Therefore, the switching valve 8
6 is a black port position, and the negative pressure chamber 805 is communicated with the atmosphere. However, due to the presence of the throttle 88, the introduction of atmospheric air is carried out slowly, the negative pressure chamber 805 maintains negative pressure for a while after the clutch 36 is engaged, and the valve body 801 of the bypass control valve 80 does not lift immediately after switching. .

The time determined by the dimensions of the aperture 88 (Tm (second
After lapse of time, the negative pressure in the negative pressure chamber 805 is no longer able to overcome the spring 804, the diaphragm 803 descends, and the bypass control valve 80 closes. Therefore, the intake air is not directed to the bypass passage 44, but the entire amount is introduced into the engine body 10.

When shifting to deceleration, the throttle valve 28 is fully closed, and when the transition line from the operating range to the non-operating range of the supercharger 34 is crossed (TA < TA _x ), the clutch 36 is opened, and at the same time Switching valve 86 is ON
is switched to OFF. At this time, negative pressure port 8
2 to the negative pressure chamber 805, the negative pressure of the negative pressure port 82 is immediately introduced into the diaphragm chamber 805, and the bypass control valve 80
to rapidly open the valve. If the bypass control valve 80 is opened slowly, the throttle valve 28 will close immediately after the clutch 36 is disengaged, and the bypass control valve 80 will also close.
Since the supercharger 34 continues to rotate for a while due to inertia, the inlet side of the supercharger 34 becomes a negative pressure, the amount of intake air decreases, and the intake air temperature may rise. In this invention, the bypass control valve 80 is opened immediately when the clutch 36 is disengaged, so the supercharger 3
The air compressed by the inertia of 4 is diverted to the bypass passage 44 and then returns to the bypass passage 44 again via the supercharger 34. Such circulation flow increases the amount of intake air, making it possible to maintain the intake air at an appropriate temperature.

In the embodiment, the supercharging condition is determined based on the throttle valve opening, but as is well known, other factors such as engine speed, vehicle speed, intake pipe negative pressure, etc. can be used for control.

[Effect of idea]

According to the present invention, in an internal combustion engine in which a supercharger is provided downstream of a throttle valve, the transition from engagement to disengagement of the clutch means during deceleration is achieved by not providing a restriction in the path of negative pressure that opens the bypass control valve. It is possible to prevent an increase in intake air temperature in the region, suppress knocking, and have the effect of reducing supercharging shock.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram of an embodiment of this invention. Second
The figure is an operation timing diagram of the electromagnetic clutch and bypass when the throttle opening changes. Figure 3 is an operational map of the mechanical supercharger and bypass control valve. 28...Throttle valve, 34...Mechanical supercharger, 36...Clutch, 44...Bypass passage,
48... Control circuit, 80... Bypass control valve, 8
4... Check valve, 86... Switching valve, 88... Throttle, 801... Valve body, 803... Diaphragm,
804... Spring, 805... Negative pressure chamber.

Claims (1)

[Scope of utility model registration request] downstream of the throttle valve in the engine intake system.
A mechanical supercharger connected to the engine drive shaft via clutch means, a passage bypassing the supercharger and connecting the downstream side of the supercharger between the downstream side of the throttle valve and the upstream side of the supercharger. In a mechanical supercharged internal combustion engine in which a bypass control valve is disposed in the bypass passage, the bypass control valve includes a valve body disposed in the bypass passage, a diaphragm connected to the valve body, and a side surface of the diaphragm on the opposite side of the valve body. The valve body normally includes a negative pressure chamber that is pressed to close the bypass passage, and a spring that normally biases the valve body to close the bypass passage. , has a switching valve that switches the negative pressure chamber to communicate with the atmosphere according to a control signal, and a throttle that controls the transmission speed of atmospheric pressure to the negative pressure chamber is provided on the atmospheric side of the switching valve; There is no throttle on the negative pressure side that controls the transmission speed of negative pressure to the negative pressure chamber, and the switching valve is activated when the clutch means is switched between opening and engagement. A control circuit is provided for switching between a position where the negative pressure chamber is connected to the pressure port and a position where the negative pressure chamber communicates with the atmosphere, whereby atmospheric pressure is introduced through the restriction when the clutch means is switched from opening to engagement. The bypass control valve is gradually closed, and the negative pressure is not introduced through the throttle when the clutch means is switched from engagement to release, so that the bypass control valve is opened immediately. Boost pressure control device for mechanically supercharged internal combustion engines.