JPH048611B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an intake pressure control device for a supercharged engine, and more particularly, to a device for controlling the intake pressure of a supercharged engine. This invention relates to an intake pressure control device for a supercharged engine.

[Prior Art] An example of a conventional device of this type is the technology described in Japanese Patent Application Laid-Open No. 101536/1983.

The technique disclosed in the above publication provides a supercharger passage having a supercharger in parallel with the intake passage, and communicates the upstream passage of the supercharger with the downstream passage of the turbocharger passage through a recirculation passage. A boost pressure control valve is provided in the middle of the recirculation passage, and a coupling mechanism is provided for controlling opening and closing of the boost pressure control valve in conjunction with a predetermined opening degree of the throttle valve. Specifically, it is constructed and operates as shown in FIG.

In FIG. 4, a throttle valve 2 provided in an intake passage 1 of a carburetor is composed of a butterfly valve or the like that rotates around a throttle shaft 3. As shown in FIG.

A supercharger 1 installed in parallel with the intake passage 1 of the carburetor.
0 is constructed as follows. The supercharger passage 11 is formed in a U-shape, and the rotating cylinder 12 of the cylindrical compressor is located at the center of curvature of the U-shaped supercharger passage 11.
locate the center of An eccentric shaft 13 is provided inside the rotary cylinder 12, and a plurality of blades 14 are made to protrude outward from the slit of the rotary cylinder 12 on the eccentric shaft 13. As the rotary cylinder 12 rotates, the blades 14
A space is formed between the four spaces, and the intake air is forced out.

Further, a recirculation passage 17 is connected between an upstream passage 15 and a downstream passage 16 of the intake air of the supercharger 10 in the turbocharger passage 11, and a supercharging pressure control valve is provided in the middle of the recirculation passage 17. 20 is provided.

A connecting mechanism 30 is provided that controls opening and closing of the supercharging pressure control valve 20 depending on the opening degree of the throttle valve 2.

The coupling mechanism 30 is configured as follows.

A cam 4 is disposed on the throttle shaft 3, and the cam 4
A rotor 5 that rolls on the outer circumference of the connecting rod 6 is provided at one end of the connecting rod 6, and the other end of the connecting rod 6 and the supercharging pressure control valve 20 are connected to each other.
A connection lever 21 is used to connect between the two.

The intake pressure control device for a supercharged engine configured as described above operates as follows.

When the engine is under low or medium load, the throttle valve 2 is slightly opened, and the boost pressure control valve 20 is thereby rotated by the connecting mechanism 30 including the throttle shaft 3, cam 4, connecting rod 6, etc. and recirculation passage 1
7 is slightly closed. Therefore, the recirculation of charge air causes a slight increase in charge pressure by the boost pressure control valve 20.

Also, when the engine is under high load, the throttle valve 2 becomes almost fully open, and the connection mechanism allows
The supercharging pressure control valve 20 becomes substantially fully open. As a result, the recirculation passage 17 is shut off, the boost pressure supplied by the supercharger 10 increases, and high output can be produced.

That is, it is possible to supply the engine with supercharging pressure that corresponds to the opening degree of the throttle valve 2 that corresponds to the load state of the engine.

[Problems to be Solved by the Invention] However, in the above-mentioned conventional intake pressure control device for a supercharged engine, the supercharger controls the opening of its supercharging pressure control valve in conjunction with the opening of the throttle valve. Because it supplies boost pressure to the engine according to the
Boost pressure was determined solely by the movement of the throttle valve, making it impossible to control boost pressure according to engine speed, making it impossible to uniformly increase engine response. That is, in order to increase the accelerator response at the initial stage when the accelerator pedal is depressed, it is necessary to open the throttle valve until the supercharging pressure control valve is fully closed.

In addition, even if the engine speed increases in response to the driver's acceleration request, the engine rotational state is not a control requirement, and furthermore, the boost pressure increases even after starting to drive at a constant speed. There were problems such as increased fuel consumption.

When the driver frequently operates the accelerator, the boost pressure changes frequently in conjunction with the accelerator, making it difficult to obtain a smooth driving feeling.

In addition to the technique disclosed in the above-mentioned publication, there is a technique disclosed in Japanese Utility Model Application Publication No. 58-6921. According to the report, the supercharging control valve is controlled in conjunction with the throttle valve using a link mechanism, and cannot correspond to the engine speed. That is, when the engine speed is below the set value, the control valve is always open, and when the engine speed is above the set value, the control valve is linked to the throttle valve, so the throttle valve and engine speed are The control valve opening is not determined by both conditions, but the control valve opening is controlled separately for the throttle valve and engine rotation, and when the engine rotation is less than the set rotation, Since the engine is not being fed, even if the accelerator is pressed, the supercharging state does not occur, and there is a problem with its responsiveness.

Furthermore, Japanese Patent Application Laid-Open No. 59-29727 developed a technology for determining boost pressure based on throttle opening and engine speed.
There is a technology published in the publication. However, this technology controls the opening and closing of the bypass valve that bypasses the engine's exhaust turbine according to the boost pressure of the turbocharger, so the driver opens the throttle opening and the required boost pressure increases. However, there is a time delay before the amount of engine exhaust gas increases.
That is, since there is a reaction delay until the supercharging pressure reaches a predetermined pressure, there is a problem that it is impossible to keep up with repeated rapid changes in opening and closing of the throttle.

Furthermore, there is a technique disclosed in Japanese Unexamined Patent Application Publication No. 57-203823 that provides a clutch mechanism for controlling the operation of a supercharger.

The technology published in the above publication defines the range in which the clutch of the mechanical supercharger is controlled on and off based on engine rotation and throttle opening. When the clutch is on, the valve closes and stops the air flow. When the clutch is off, the valve is open to allow airflow to be sucked in. However, in this opportunistic supercharger, since the clutch is controlled on and off, the supercharged state and non-supercharged state change rapidly, resulting in a large shock.

Therefore, the present invention has developed a supercharger that detects supercharging pressure to uniformly increase accelerator response even when the engine speed fluctuates, reduces fuel consumption, and provides a smooth running feeling. The object of the present invention is to provide an intake pressure control device for an engine with an engine.

[Means for Solving the Problems] The intake pressure control device for a supercharged engine according to the present invention communicates a supercharger provided in an intake passage with an upstream passage and a downstream passage of the supercharger. a recirculation passage, a boost pressure control valve disposed in the middle of the recirculation passage, a throttle opening sensor for detecting the load condition of the engine, and an engine rotation speed sensor for detecting the rotation speed of the engine; and a sensor that detects the boost pressure state, and compares the current boost pressure with the boost pressure read from a memory that stores the boost pressure according to the load state and engine speed of the engine, and compares the boost pressure with the current boost pressure. When the output of the means is greater than or equal to the allowable value, the actuator for controlling the opening/closing of the boost pressure control valve is controlled in a direction in which the output of the comparing means becomes smaller; When the boost pressure control valve is fully open, the clutch mechanism releases the supercharger.

[Operation] According to the present invention, the load condition and rotation speed of the engine are detected by a sensor, and an address is specified based on the obtained engine load condition and rotation speed, so that the engine load condition and rotation speed are determined according to the engine load condition and rotation speed. Reads the specified engine boost pressure value from the memory that stores the boost pressure. Then, the current supercharging pressure of the engine is detected by a supercharging pressure sensor that detects the state of supercharging pressure, and the comparing means compares the supercharging pressure read from the memory with the current supercharging pressure. When the output of the comparison means is equal to or greater than the designated boost pressure value and the allowable value, the actuator controls the boost pressure control valve to increase or decrease the boost pressure, and detects the engine boost pressure at that time. The detected output is fed back to control the supercharging pressure supplied to the engine to a specified supercharging pressure value corresponding to the optimum engine load condition and engine speed. Further, when the output of the comparison means is not above the allowable value and the boost pressure control valve is fully open,
The clutch mechanism releases the supercharger.

[Embodiment] FIG. 1 is an overall configuration diagram of an intake pressure control device for a supercharged engine according to a first embodiment of the present invention. In the figure,
The same reference numerals and symbols as in FIG. 4 indicate the same or equivalent parts as in the conventional device. here,
In particular, only the points that are different from conventional devices will be described.

In the figure, the throttle sensor SS is a known sensor that detects the opening of the throttle valve 2.
In this embodiment, a potentiometer PM is directly connected to the throttle shaft 3 of the throttle valve 2, and the opening degree of the throttle sensor SS is detected as the potential at the connection point between the series resistor R1 and the potentiometer PM. Instead of the potentiometer PM, mechanically connect a rotary switch or a rotating shaft of a code plate, etc., and convert a change in contact or a change in resistance value to a change in potential. It is also possible to use a device that detects and determines the degree of opening. Since the object detected by the throttle sensor SS is the load condition of the engine, when implementing the present invention, it is not necessarily necessary to use the output of the throttle sensor SS, but it is necessary to detect the rotation speed, torque, fuel supply condition, etc. The amount of depression of the accelerator pedal, etc. may also be used. However, by using the throttle sensor SS as the engine load condition, it is easiest to obtain a condition that approximates the load condition.

The engine rotation speed sensor ES detects the engine rotation speed by the rotation of the permanent magnet MG connected directly or indirectly to the engine shaft.
A reed switch inserted in series with the engine is turned on and off to generate pulses with a frequency proportional to the engine speed. When detecting engine speed as vehicle speed, the speed at which a pulse with a frequency proportional to the engine speed is obtained is obtained from the on/off signal of a reed switch placed near the permanent magnet MG connected to the speedometer cable. A sensor may be used. Note that these engine rotational speed sensors or speed sensors are well known, and other known sensors other than those having the mechanical switch can also be used. Alternatively, the engine rotation speed may be determined by detecting pulses of an ignition signal from an ignition circuit, and the number of pulses may be used as the engine rotation speed. In this case, the engine speed can be detected simply by adding an electrical circuit to a conventional engine.

The control valve CV uses its solenoid to connect the output of the boost pressure control circuit CPU to the driver circuit DR.
When the solenoid is energized via 2, negative pressure is sent from the surge tank ST side to the actuator AC side, and when the solenoid is de-energized, the negative pressure of the actuator AC is discharged to the atmospheric pressure side.

In addition, the pressure sensor PS used as a boost pressure sensor to detect boost pressure is a well-known semiconductor strain gauge.
The current supercharging pressure in the downstream passage 16 of the supercharger 10 is measured. Since the pressure sensor PS obtains the boost pressure actually supplied to the engine, the setting conditions of the boost pressure control valve 20, the supercharger 10, the supercharger passage 11, and the recirculation passage 17 are determined. For example, by setting a pressure sensor PS in the turbocharger passage 11, recirculation passage 17, etc., and applying the pressure value directly or by assigning a constant, supercharging of the downstream passage 16 of the turbocharger 10 can be performed. It may be used by converting it into pressure.
A pressure sensor also used as a boost pressure sensor
The PS is not limited to semiconductor pressure sensors such as semiconductor strain gauges, but also capacitance pressure sensors, piezoelectric pressure sensors, and the like can be used.

The actuator AC controls the boost pressure control valve 20 based on the output of the boost pressure control circuit CPU.
Surge tank ST accumulated by a vacuum pump (not shown), etc. with a known negative pressure actuator
The negative pressure is guided to the negative pressure chamber through the control valve CV, and the supercharging pressure control valve 20 is rotated by the movement of the rod LT. Usually, the negative pressure in the negative pressure chamber is controlled by a control valve.
This is done by controlling the duty ratio of the CV solenoid. The actuator AC used here controls the opening and closing of the boost pressure control valve 20 in response to the electrical output of the boost pressure control circuit CPU, so when implementing the present invention, the negative pressure actuator is not necessarily used. It is not necessary to use an actuator that is controlled electromagnetically, and an actuator that is controlled electromagnetically can also be used. For example, known solenoids, motors, etc. can be used.

The supercharging pressure control circuit CPU, which controls the duty ratio of the solenoid of the control valve CV by receiving the output of the throttle sensor SS, the output of the engine speed sensor ES, and the pressure sensor PS, has an A-D conversion circuit built in or externally installed. A microcomputer is used.

Furthermore, the supercharger 10 in this embodiment has a clutch mechanism CL interposed between the engine rotating shaft and the compressor shaft of the supercharger 10, so that the engine rotating shaft and the compressor shaft of the supercharger 10 are connected to each other. are connected. The clutch mechanism CL is intermittent depending on the output of the boost pressure control circuit CPU,
Preferably, the clutch mechanism CL itself is an electromagnetic clutch that can be turned on and off in response to an electrical signal. This clutch mechanism CL is controlled intermittently by the output of the boost pressure control circuit CPU via the driver circuit DR1.

Note that the hatched area in the explanatory diagram of the memory map for boost pressure setting value in FIG. This indicates the area to be separated from the load. The region of the supercharging pressure command value P0 in this embodiment corresponds to the clutch mechanism that transmits rotational force to the supercharger 10.
This is the area where CL is turned off. Note that the range in which the clutch mechanism CL is turned off does not necessarily have to be set in the range of the supercharging pressure command value P0.
For example, the clutch mechanism CL may be set in the on region near the boundary line with the supercharging pressure command value P1 in the region of the supercharging pressure command value P0, and the other parts may be set in the off region. In any case, the clutch mechanism should be
It is sufficient to turn CL off.

Next, the operation of the intake pressure control system for a supercharged engine according to this embodiment using a microcomputer as the supercharging pressure control circuit CPU will be explained using the flowchart shown in FIG.

This program is for the ignition switch or a switch linked to the ignition switch.
When the entire system of the intake pressure control device of this supercharged engine is activated by SW, program control is started.

First, in step S21, the memory necessary to execute this system is initialized, and inputs and outputs such as each sensor input and the output of the boost pressure control valve 20 are performed. In step S22, the current opening degree of the throttle valve 2 is detected by the throttle sensor SS as the engine load condition. In step S23, the engine rotation speed is detected from the engine rotation sensor ES. These, step S22 and step S23
Then, obtain the current engine load state and engine speed. Then, in step S24, a supercharging pressure command value Pa is read from the ROM based on the engine load condition and engine speed.

That is, the ROM stores the engine rotation speed (vehicle speed) and throttle valve opening, as shown in the explanatory diagram of the memory map for boost pressure setting value in Fig. 3 (explanation of the shaded area will be given in the second embodiment). In relation to this, the maximum boost pressure in the area of boost pressure indication value Pa is P4,
The minimum boost pressure is set as P0, and its range is set in five stages: P4>P3>P2>P1>P0.

The boost pressure command value P0 is the maximum opening of the boost pressure control valve 20, so the boost pressure is the minimum, and the boost pressure command value P4 is the minimum opening of the boost pressure control valve 20. Since it is in the open state, its supercharging pressure is at its maximum.

This boost pressure set value memory map stores data based on actual measurements or design values of engine load characteristics.
It is stored in ROM.

In step S24, after reading out the supercharging pressure instruction value Pa from the ROM by specifying the address based on information such as engine speed and throttle valve opening, step
Pressure sensor that detects the current boost pressure status in S25
Obtain the boost pressure detection value Px actually supplied to the engine from PS. Then, in step S26, the difference between the boost pressure command value Pa read from the memory map in step S24 and the detected boost pressure value Px that is currently actually being supplied to the engine is calculated, and the absolute value of the difference is
When it is less than the tolerance δ determined based on the range of the boost pressure command value Pa, sensor error, boost pressure control error, etc., in step S27, the output means controls the boost pressure control valve 20. The movement of the rod LT of the actuator AC that drives the supercharging pressure control valve 20 to maintain the opening is stopped.

Then, in step 28, the boost pressure command value Pa is changed to Pa
= P0, and when it is determined that the minimum boost pressure command value P0, the clutch mechanism CL is activated in step 29.
is in the off state, the supercharger 10 is removed from the engine load.
Separate.

When it is determined in step S26 that |Pa−Px|<δ, the supercharging pressure command value Pa set according to the memory map in the ROM and the current detected supercharging pressure value
Since there is a difference between Px and the difference is larger than the tolerance δ, step S30
When the boost pressure instruction value Pa is not the minimum boost pressure instruction value P0, the clutch mechanism CL is turned on in step 31, and the boost pressure instruction value Pa of the boost pressure control valve becomes equal to the minimum boost pressure instruction value P0. When, as it is,
In step S32, the supercharging pressure command value Pa is compared with the current supercharging pressure detection value Px, and the increasing speed and deceleration are determined. When the increasing speed is detected, the current supercharging speed is determined by the output means in step S33. It is output to the actuator AC to drive the supercharging pressure control valve 20 in the direction in which the detected pressure value θx increases. When the acceleration is reduced, in step S34, the output means outputs an output to the actuator AC to drive the boost pressure control valve 20 in a direction in which the current detected boost pressure value θx becomes smaller.

At this time, depending on the engine speed and throttle valve opening, the control stage in the region of the boost pressure detection value Px read out by specifying the address in the memory map of the ROM is changed from the boost pressure command value P4 to the boost pressure command. If it moves in the direction of value P0, the boost pressure will be controlled in stages.

For example, suppose that when stepping on the accelerator pedal to increase acceleration, the vehicle enters the control region of the supercharging pressure command value P4. If the amount of depression of the accelerator pedal is constant, the engine speed will gradually increase,
The rod LT of the actuator AC is moved step by step from the control area of the boost pressure instruction value P4 to P3, and then to the boost pressure instruction values P2, P1, and P0, and the boost pressure control valve 20 is gradually opened. , the supercharging pressure supplied to the engine from the supercharger 10 can be gradually reduced.

In this way, in this embodiment, the ROM has a built-in memory map that stores boost pressure according to the load characteristics of the engine, the boost pressure set value Pa read from the memory map, and the current detected boost pressure Px. When the output of the comparison means is equal to or higher than the allowable value δ of the boost pressure request state, the pressure of the boost pressure is controlled according to the memory contents of the memory map, and the output of the comparison means is When the supercharger is not in the supercharging pressure request state, the supercharger can be controlled to be in the released state by the clutch mechanism CL.

Therefore, in a state where supercharging pressure is no longer required, the clutch mechanism CL can disconnect the supercharger 10 from the engine load.
A stable engine speed can be maintained during idling. Further, by disconnecting the supercharger 10 from the engine load during idling, it is possible to prevent the generation of noise due to the operating sound of the compressor of the supercharger 10. Then, since the supercharger 10 is released in a state where supercharging pressure is no longer required,
The life of the compressor used in the supercharger 10 can be extended.

As described above, the supercharging pressure control circuit CPU of the intake pressure control device for a supercharged engine according to the present embodiment is connected to a supercharger connected to the intake passage 1. Supercharger 10 installed in passage 11
, a recirculation passage 17 that communicates the upstream passage 15 and downstream passage 16 of the supercharger 10 of the turbocharger passage 11, and a boost pressure control valve disposed in the middle of the recirculation passage 17. 20, a throttle sensor SS that detects the load condition of the engine, an engine speed sensor ES that detects the engine speed, and a pressure sensor that detects the boost pressure supplied to the engine.
The intake pressure of a supercharged engine consists of a boost pressure sensor consisting of a PS, and a boost pressure control circuit CPU that controls the actuator AC which controls the opening and closing of the boost pressure control valve 20 based on the output of each of these sensors. In the control device, the boost pressure control circuit CPU stores a memory storing boost pressure according to engine load characteristics, a boost pressure setting value Pa read from the memory, and a current detection value Px of boost pressure. When the output of the comparison means is equal to or higher than the allowable value of the boost pressure request state, the pressure of the boost pressure is controlled according to the stored contents of the memory, and the output of the comparison means is When the supercharging pressure is not required, the clutch mechanism CL controls the supercharger 10 to be released.

Therefore, according to the intake pressure control device for a supercharged engine of this embodiment, by detecting the engine speed, throttle valve opening, and supercharging pressure, the overcharging is controlled according to the engine speed and the engine load state. It is possible to control supply pressure in accordance with engine load characteristics.

Additionally, when the driver suddenly depresses the accelerator pedal to request an increase in speed, the opening of the throttle valve changes rapidly depending on the engine speed and engine load condition, causing the engine load condition to reach the target value. Since the supercharging pressure gradually decreases, there is less wastage in fuel consumption, and smooth driving is possible without giving the driver shocks such as hunting due to changes in speed due to the decrease in the supercharging pressure.

When supercharging pressure is no longer needed, the clutch mechanism CL can disconnect the supercharger 10 from the engine load, making it possible to maintain a stable engine speed, especially during idling. . Furthermore, when idling, the supercharger 1
By separating the compressor 0 from the engine load, it is possible to prevent the generation of noise due to the operating sound of the compressor of the supercharger 10. Since the supercharger 10 is stopped in a state where supercharging pressure is no longer required, the life of the supercharger 10, particularly the life of the compressor, can be extended.

[Effects of the Invention] As described above, the present invention includes an engine load state and engine speed sensor, a sensor for detecting boost pressure, and a supercharging pressure that is stored in accordance with the engine load state and engine speed. It comprises a memory, and a comparison means for comparing the supercharging pressure read from the memory and the current supercharging pressure, and comparing the supercharging pressure read from the memory and the current supercharging pressure, and comparing the output of the comparing means. When the supercharging pressure is greater than or equal to the allowable value of the specified supercharging pressure, the actuator that controls the opening and closing of the supercharging pressure control valve is controlled to increase or decrease the supercharging pressure, the supply supercharging pressure at that time is detected, and the Since the detection output is fed back and the boost pressure supplied to the engine is controlled to the optimum boost pressure specified value according to the engine load condition and engine speed, it is possible to control the boost pressure supplied to the engine. Feedback allows precise boost pressure control. Furthermore, even when the engine condition changes, the accelerator response can be uniformly increased and the fuel consumption can be maintained at an optimum level, so the fuel consumption is reduced and a smooth driving feeling can be obtained.

In addition, the feedback of the supercharging pressure supplied to the engine makes it possible to ignore the effects of changes over time in the turbocharger compressor and control valve, and since the supercharging pressure is detected, the engine's supercharging pressure Knocking and engine damage can be prevented without generating abnormal pressure.

[Brief explanation of drawings]

Fig. 1 is an overall configuration diagram of an intake pressure control device for a supercharged engine according to an embodiment of the present invention, and Fig. 2 shows the operation of the intake pressure control device for a supercharged engine according to an embodiment of the present invention. Flowchart of boost pressure control circuit,
FIG. 3 is an explanatory diagram of a storage example of a memory map for supercharging pressure setting values, and FIG. 4 is an overall configuration diagram of a conventional intake pressure control device for a supercharged engine. In the figure, 1: intake passage, 10: supercharger, 1
1: Supercharger passage, 15: Upstream passage, 16: Downstream passage, 17: Recirculation passage, 20: Supercharging pressure control valve, ES: Engine speed sensor, SS: Throttle sensor, PS: Pressure sensor , AC: actuator, CL: clutch mechanism. In addition, in the figure,
The same reference numerals and symbols indicate the same or equivalent parts.

Claims (1)

[Scope of Claims] 1. A supercharger provided in an intake passage, a recirculation passage that communicates an upstream passage and a downstream passage of the turbocharger, and a supercharging pressure disposed in the recirculation passage. a control valve; a throttle opening sensor that detects the load state of the engine; an engine rotational speed sensor that detects the rotational speed of the engine; a boost pressure sensor that detects the boost pressure supplied to the engine; an actuator that controls opening and closing of a boost pressure control valve; a memory that stores boost pressure according to the load condition and rotational speed of the engine; and a comparison between the boost pressure read from the memory and the current boost pressure. a comparison means for controlling the actuator in a direction in which the output of the comparison means decreases when the output of the comparison means is equal to or greater than an allowable value; 1. An intake pressure control device for a supercharged engine, comprising a clutch mechanism that releases a supercharger when a supercharging pressure control valve is fully open.