JPS614829A - Intake device for engine associated with supercharger - Google Patents

Abstract

PURPOSE:To improve the reliability in an intake device where a supercharger is arranged in the upstream of carburetor, by providing a controller for driving a pressure control valve such as an exhaust bypass valve upon abrupt deceleration thereby reducing excessive positive pressure for causing oil leakage of carburetor. CONSTITUTION:Upon departing of foot from an accelerator pedal 9 under abrupt deceleration, a microswitch 3a of pressurized carburetor 3 is turned on to changeover a three-way valve 6 thus to lead the output pressure of compressor 1a which is equal to that in a pressure receiving chamber 5b communicating to the downstream of compressor 1a of turbocharger 1 into the pressure receiving chamber 5a of actuator 5 through a path 6c. Consequently, a disphragm member 5c is moved to the right through a compression spring 5h thus to contact an actuator rod 5g against a diaphragm member 5d. Since the combined force of the output pressure of compressor 1a and the spring 5h force is applied onto said member 5d to the right, the opening of an exhaust bypass valve 7 will increase thus to lower the output pressure quickly.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to an intake system for a supercharged engine in which a supercharger is disposed upstream of a carburetor, and in particular, the present invention relates to an intake system for a supercharged engine in which a supercharger is disposed upstream of a carburetor. The present invention relates to an intake system for a supercharged engine suitable for reducing excessive positive pressure.

[Background of the invention]

An intake system for a supercharged engine using a conventional pressurized carburetor is described in Japanese Patent Application Laid-Open No. 56-88944 as a countermeasure against delay in secondary valve response caused by excessive positive pressure applied to the carburetor during deceleration. As shown in the figure, the residual pressure of the actuator that opens and closes the secondary throttle valve is released to the atmosphere.
As described in No. 3, a forced return system for the secondary throttle valve has been proposed in which the actuator and the secondary throttle valve are separated.

However, although both methods are satisfactory as a countermeasure for the secondary valve response delay, they do not solve the root cause of the excessive positive pressure itself that occurs during deceleration, so there are problems in terms of fuel leakage and the durability of the secondary valve diaphragm member. It was a disadvantage.

[Purpose of the invention]

The purpose of the present invention is to prevent fuel leakage from the carburetor, damage to the secondary valve diaphragm, and delayed response of the secondary valve due to sudden vehicle deceleration in the intake system of a supercharged engine in which the supercharger is placed upstream of the carburetor. Reduce the positive pressure within the week that may cause
An object of the present invention is to provide an intake system for a supercharged engine with improved reliability.

[Narrowness of the invention]

The present invention is characterized in that in an intake system for a supercharged engine in which the supercharger is placed upstream of the carburetor, the throttle valve opening is detected to drive the pressure control valve of the supercharger. A control device is provided to limit excessive positive pressure that occurs when the vehicle suddenly decelerates.

[Actual case of invention]

The present invention will be explained below by way of an example.

In FIG. 1, a turbocharger 1 is arranged downstream of an air cleaner (not shown), and an air chamber 2, a pressurized carburetor 3, and an engine 4 are arranged downstream of the turbocharger 1 in this order.

The turbocharger 1 includes a compressor 1a that compresses intake air, a turbine 1b that rotates using exhaust gas energy, and an actuator 5 that bypasses the exhaust gas and controls the compressor outlet pressure.

The actuator 5 has a pressure receiving chamber 5a communicating with the three-way solenoid valve 6.
, a pressure receiving chamber communicating downstream of the compressor 1a) b1, a diaphragm member 5c separating the pressure receiving chambers.

Another diaphragm member 5d forming the pressure receiving chamber 5b
, an actuator rod 5e having one end fixed to the diaphragm member 5d and the other end connected to the exhaust bypass valve 7, an actuator rod Sgs having one end fixed to the diaphragm member 5C and the other end having a contact portion 5f to the diaphragm member 5d. A compression spring 5h and an actuator rod 5e are located in the pressure receiving chamber a and regulate the operation of the diamond slam member 5C.
It is constituted by a compression spring 51 located on the side and regulating the operation of the diaphragm member 5d.

The three-way solenoid valve 6 includes a passage 6a leading to the pressure receiving chamber of the actuator 5, an atmosphere opening passage 6b, and a passage 6C leading downstream of the compressor 1a. Furthermore, the three-way solenoid valve 6 is connected to a microswitch 3a of the pressurized vaporizer 3 via a battery 8.

Reference numeral 3b designates a throttle valve of the pressurized carburetor 3, the end of the valve shaft 3C of which is connected to the accelerator pedal 9 via a well-known mechanism, and is controlled to open and close in conjunction with the depression of the accelerator pedal 9.

First, in the idle state, the accelerator pedal 9 is not depressed, so the microswitch 3a is turned on, and the compressor outlet pressure is guided to the pressure receiving chamber 5a by the three-way solenoid valve 6. Therefore, the pressures in the pressure receiving chambers 5a and 5b are equal and approximately atmospheric pressure.

The actuator rod 5g is in contact with the diaphragm member 5d via a contact portion 5f by a compression spring 5h. Here, the set load of the compression spring 51 is set to match the maximum boost pressure that drives the exhaust bypass valve 7, and the set load of the compression spring 5h is set to be weaker than that. Therefore, the diaphragm member 5d moves to the left due to the force of the compression spring 51, and the exhaust bypass valve 7 connected via the actuator rod 5e is closed.

When accelerator pedal 9 is depressed, micro switch 3
a is turned off, and atmospheric pressure is introduced into the pressure receiving chamber 5a by the three-way solenoid valve 6. Therefore, as the depression is increased, the compressor outlet pressure overcomes the compression spring 5h, the diaphragm member 5C moves to the left, and the actuator rod 5g moves from the diaphragm member 5d.

When the compressor outlet pressure reaches the set maximum supercharging pressure, the diaphragm member 5d moves to the right to open the exhaust valve 7 and maintain the compressor outlet pressure at the set value.

Next, the situation during sudden deceleration will be explained using FIG. 2.

During sudden deceleration, the foot is removed from the accelerator pedal 9 and the microswitch 3a is turned on, so the three-way solenoid valve is switched and a compressor outlet pressure of the same magnitude as the pressure receiving chamber 5b is introduced into the first pressure receiving chamber 5a. The diaphragm member 5C moves to the right by the compression spring 5h, and the actuator rod 5g comes into contact with the diaphragm member 5d. Therefore, the force of the compression spring 51 is applied to the right, and the resultant force of the compressor outlet pressure and the compression spring 5h is applied to the diaphragm member 5d. The opening degree of the compressor increases, making it possible to quickly reduce the compressor outlet pressure.

According to this embodiment as described above, by modifying the conventional exhaust valve drive actuator (Ipass valve drive actuator), it is possible to reduce the excessive positive pressure generated when the vehicle suddenly decelerates without changing the conventional pressure control characteristics. It is highly effective in solving the problems of fuel leaks, secondary valve diaphragm damage, and secondary valve response delays.

Note that similar effects can be obtained by using an intake relief valve as the pressure control valve.

〔Effect of the invention〕

According to the present invention, in a system in which the supercharger is placed upstream of the carburetor, excessive positive pressure applied to the carburetor during sudden deceleration can be quickly reduced, thereby preventing fuel leakage, damage to the secondary valve diaphragm, It is highly effective in solving response delays.
The safety and reliability of the vaporizer can be improved.

[Brief explanation of drawings]

FIG. 1 is an overall schematic diagram showing an embodiment of the present invention at full load, and FIG. 2 is an overall schematic diagram at sudden deceleration. 1... Turbocharger, 3... Pressurized carburetor, 3a
...Micro switch, 4...Engine, 5...
Actuator, 6... Three-way solenoid valve, 7... Exhaust bypass valve, 9... Accelerator pedal. Figure l Figure 2

Claims (3)

[Claims] 1. An intake system for a supercharged engine in which a supercharger is disposed upstream of a carburetor, characterized in that the supercharger is equipped with a control device that drives a pressure control valve of the supercharger during sudden deceleration. Engine intake system. 2. An intake system for a supercharged engine according to claim 1, wherein the pressure control valve is an exhaust bypass control valve. 3. An intake system for a supercharged engine according to claim 1, wherein the pressure control valve is an intake relief control valve.