JPH063140B2 - Engine supercharging control device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a supercharging control device in an engine supercharging device in which intake air supercharging is performed using an air pump driven by the engine.

(Prior Art) Conventionally, in a supercharged engine, particularly a supercharged engine for an automobile or the like which is connected to an external load through a transmission, as disclosed in, for example, Japanese Patent Laid-Open No. 58-30415. An air pump that is driven by the engine and that is turned on and off according to the load of the engine is provided in the middle of the intake system passage, and a communication passage that connects the suction side and the discharge side of the air pump by bypassing the air pump. A control valve that opens and closes the communication passage according to the load of the engine, and controls the control valve when the transmission is set to a low speed stage (for example, the first speed stage or the second speed stage). By closing and operating the air pump, the output of the engine is improved due to the supercharging effect of the air pump, and the operability at low speed stages where acceleration is required is improved. A device has been proposed.

(Problems to be Solved by the Invention) However, in the above-described conventional supercharging control device, when the transmission is set to the low speed stage, supercharging is started regardless of the operating state at that time. For example, even when a low-load operation is performed at a low speed stage such as a slow running operation, in other words, even when the acceleration demand is low and the output is not required to be increased so much, supercharging is performed by the air pump to unnecessarily output. However, there is a problem in that the reliability of the air pump is impaired.

The present invention has been made in view of the above points, and an object of the present invention is to set a drive start load of an air pump and to appropriately set the load according to a gear position of the transmission, so that The objective is to obtain the optimum output characteristics according to each shift speed and to improve the reliability of the air pump by avoiding unnecessary driving of the air pump while ensuring good acceleration at low speeds.

(Means for Solving the Problems) In order to achieve the above object, the solution means of the present invention is provided by an engine in the middle of an intake system passage of an engine connected to an external load through a transmission as described above. An air pump that is driven and whose drive is turned on / off according to the load of the engine, a communication passage that communicates the suction side and the discharge side of the air pump by bypassing the air pump, and the communication passage according to the load of the engine. And a control valve for opening and closing the control valve, and closing the control valve when the air pump is driven. When the drive start load, which is the drive start reference point of the air pump whose drive is turned on and off according to the engine load, is set in a plurality of stages, and the drive start load is set to the low speed stage. The driving start load setting means is set to set the load so that it is on the higher load side than when it is set to the high speed stage.

(Operation) With the above configuration, in the present invention, the drive start load of the air pump is set to a plurality of stages, and the higher load side is set as the transmission becomes a lower speed stage. In the high speed stage, supercharging is started from the low load range and the engine output is increased. In addition, at low speed with good acceleration (blow-up), by starting supercharging from the higher load side than at high speed, while maintaining good acceleration at low speed, the air pump with a preset load Since the air pump does not operate until the drive start load is reached, supercharging is not performed when low load operation is performed at a low speed stage, such as during slow running.
Unnecessary driving of the air pump is avoided.

(Embodiment) A preferred embodiment of the present invention will be described below with reference to FIGS. 1 to 5.

FIG. 1 shows a schematic system of a first embodiment to which the present invention is applied to a fully supercharged engine. In FIG. 1, reference numeral 1 denotes an automobile engine connected to an external load via a transmission (not shown), and 2 denotes an intake passage as an intake system passage for supplying intake air to the engine 1.

The most upstream end of the intake passage 2 is opened to the atmosphere via the air cleaner 3, and the intake passage 2 immediately downstream of the air cleaner 3 is provided with an air flow meter 4 for detecting the intake air amount. Further, on the downstream side of the intake passage 2, a throttle valve 5 whose opening is adjusted by the depression amount of the accelerator pedal 15 to control the intake air amount, and a fuel injection valve 6 which injects fuel to the downstream side thereof are arranged. . A vane type air pump 7 for supercharging the intake air is arranged in the intake passage 2 at an intermediate position between the air flow meter 4 and the throttle valve 5. The air pump 7 is connected to the engine 1 via an electromagnetic clutch 9 which is controlled to be turned on and off by a control unit 8 which will be described later, and is selectively driven or stopped by an ON-OFF operation of the electromagnetic clutch 9. .

Further, the suction side and the discharge side of the air pump 7 of the intake passage 2 are communicated with each other via a communication passage 10 that bypasses the air pump 7. A control valve 11 for controlling opening / closing of the communication passage 10 is arranged in the communication passage 10.
The control valve 11 is opened / closed by a pulse motor 12 whose operation is controlled by a control unit 8 described later.

The control unit 8 receives the intake pressure signal C1 output from the pressure sensor 13 provided on the discharge side of the air pump 7,
Throttle opening sensor 1 attached to the throttle valve 5
Throttle opening signal (load signal) C2 output from 4
And a shift signal C3 output from a shift switch 16, which will be described later, to operate to output a clutch signal C4 to the electromagnetic clutch 9 and an on-off valve signal C5 to the pulse motor 12 to output air to the air pump 7. Control valve 1
1 is controlled, and the operation mode of the engine is controlled to be switched between supercharging operation and non-supercharging operation according to the engine load. That is,
The control unit 8 operates in the supercharging operation region (the maximum output characteristic diagram L _{0 in} FIG. 4 and the drive start load curves L ₁ , L of the air pump 7 corresponding to each shift stage of the transmission described later in FIG. 4). ₂ within each operating range), the air pump 7 is driven with the control valve 11 closed to perform the supercharging operation. In a region other than the above-mentioned region in FIG. 4, the air pump 7 is stopped and the control valve 11 is opened to perform the non-supercharging operation.

Next, the operating characteristics of the air pump 7 and the control valve 11 based on the control of the control unit 8 will be described in detail with reference to the gear position of the transmission. The shift switch 1
6 outputs a shift signal C3 corresponding to each gear position of the 5-gear transmission.

As shown in FIGS. 2 to 4, the air pump 7 has a throttle opening corresponding to a drive stop load, which is a drive stop reference point, fixed at an opening θ ₁ , but a drive start reference point thereof. The throttle opening corresponding to the starting load is set in five stages according to the shift speed of the transmission. That is, the opening degree corresponding to the drive start load of the air pump 7 is the opening degree θ ₂ (θ ₂ > when the shift speed is set to the fifth speed (overtop) as shown in FIGS. 2 and 3. θ ₁ )
When the fourth speed is set, the opening θ ₃ (θ ₃ > θ
₂ ), when the third speed is set, the opening θ ₄ (θ ₄
> Θ ₃ ) and the second speed is set, the opening θ
₅ (θ ₅ > θ ₄ ), and when the first speed is set, the opening degree θ ₆ (full open> θ ₆ > θ ₅ ) is set. 1 out of each throttle opening at each gear
The opening degrees θ ₆ and θ ₅ corresponding to the first speed and the second speed are relatively high openings (on the high load side) because these speeds are usually in the operating range with good acceleration (blow-up). It is set to the side (in other words, it does not supercharge in the low load range). On the other hand, the opening degrees θ ₄ , θ ₃ and θ ₂ corresponding to the shift speeds from the 3rd speed to the 5th speed are relatively low because the shift speeds are usually in the operating range where high output is required. Is set to the degree (low load) side (in other words, supercharging is performed from a lower load range). As a result, the drive start load of the air pump 7 is set to a plurality of stages, and the drive start load of the air pump 7 is set to a high speed stage when the transmission is set to a low speed stage. The drive start load setting means 17 for setting the load to be higher than that in the case is configured.

Therefore, as shown in FIG. 4, in the high speed stage where a high output is required, the supercharging is started from a lower load operation range, so that the output characteristics in the high speed stage are improved and the smooth and powerful output performance is improved. Will be obtained. Further, in the low speed stage, the driving of the air pump 7 is stopped in the low load operating range, so that it is unnecessary in the case of performing the low load operation in the low speed stage (in other words, the low output operating range) such as the slow running mode. Since the driving of the air pump 7 is avoided, the reliability of the air pump 7 can be improved, and the output loss (driving torque of the air pump 7) can be reduced. Also, this low speed stage has good acceleration (upward blowing), and in the high load operation range where the actual acceleration is requested, supercharging is performed by driving the air pump 7 and the output is increased, so good acceleration is achieved. The driving performance can be secured and there is no problem in drivability.

Further, in this embodiment, since a predetermined hysteresis is provided between the drive start load and the drive stop load of the air pump 7 regardless of the position of the shift speed, the occurrence of surging of the air pump 7 is effective. Will be prevented.

Further, as shown in FIG. 2, the control valve 11 has a fixed throttle opening θ ₇ corresponding to the engine load which is the reference for starting the opening operation, like the air pump 7.
The throttle opening corresponding to the engine load, which is the reference for starting the closing operation, is set to five stages according to the shift speed of the transmission. That is, the throttle valve opening degree corresponding to the closing operation start load of the control valve 11 is the opening degree θ ₂ when the shift speed is set to the fifth speed, and the opening degree θ when the shift speed is set to the fourth speed. _When the third speed is set to 3, the opening θ ₄
When the second speed is set, the opening θ ₅ is set, and when the first speed is set, the opening θ ₆ is set. That is, the closing operation start position of the control valve 11 is set to the same value as the drive start load of the air pump 7 corresponding to the same speed. When the control valve 11 is actuated in the closing direction, the control valve 11 starts to close at the same time when the air pump 7 is driven, and gradually becomes fully closed. That is, the shift stage becomes the fully closed opening theta ₈ to start the closing operation in opening theta ₂ when the fifth speed, when the fourth speed opening theta start the closing operation in opening theta ₃
It is fully closed at _9th speed, starts closing operation at opening θ ₄ at 3rd speed, and fully closes at opening θ ₁₀ and opens at 2nd speed.
_{Since the} closing operation is started at ₅ and is fully closed at the opening θ ₁₁ , the closing operation is started at the opening θ ₆ and is fully closed at the opening θ ₁₂ in the first speed. Therefore, immediately after the driving of the air pump 7 is started. Is a part of the intake air pressurized by the air pump 7
Relief from 0 to the upstream side of the air pump 7, and the intake pressure gradually rises. Further, when the control valve 11 is operated in the opening direction, the opening operation of the control valve 11 is started at the opening degree θ ₇ on the higher load side than the opening degree θ ₁ at which the air pump 7 is stopped to be driven. Supply effect is control valve 11
The intake pressure gradually decreases with the opening operation, and the intake pressure gradually decreases after the driving of the air pump 7 is stopped. Therefore, the air pump 7
There is no sudden change in the intake pressure at the start of driving and the stop of driving, so that the occurrence of a torque shock that makes the driver feel uncomfortable is prevented.

Next, drive control of the air pump 7 by the control unit 8 will be described with reference to the flowchart of FIG. 5. First, after initializing in step S ₁ , drive characteristics of the air pump 7 in step S ₂ are shown in FIG. Read from map diagram. Next, to detect the current gear at Step S _3, a throttle opening degree further corresponding to the drive start load of the air pump 7 in the shift stage at Step S ₄ theta
After reading i, the current throttle opening θ is detected in step S ₅ , and the drive or stop signal (clutch) of the air pump 7 (clutch) is detected according to the magnitude of the detected opening θ and the opening θi in step S ₆ . The signal C4) is output to drive and control the air pump 7.

As described above, when the drive start load of the air pump 7 is controlled according to the shift speed of the transmission, the supercharging characteristic that matches the functional characteristic of each shift speed can be obtained. That is, in the high-speed stage where a high output is required, the air pump 7 can be driven from a lower load range to realize a more powerful and smooth output performance, and on the other hand, good acceleration (blow-up) is achieved. By driving the air pump 7 at a higher load side in the low speed stage than in the high speed stage, unnecessary acceleration of the air pump 7 is avoided while ensuring good acceleration, and the reliability of the air pump 7 is improved. It becomes possible to obtain.

FIG. 6 shows a second embodiment of the present invention applied to a partially supercharged engine. The same parts as those in FIG. 1 are designated by the same reference numerals and detailed description thereof will be omitted.

In FIG. 6, 20 and 21 are the engine 1 respectively.
Are the main intake system and the auxiliary intake system that compose the intake system.
The main intake system 20 is constituted by a main intake passage 22 having an upstream end connected to the air cleaner 3 and a main intake port 22a as a downstream end opened to the combustion chamber 1a of the engine 1.
A main throttle valve 23 that controls the amount of intake air from the main intake passage 22 is disposed in the main intake passage 22. Further, a fuel injection valve 24 is provided downstream of the main throttle valve 23 of the main intake passage 22, and a mediating plate type air flow sensor 25 for detecting the total intake air amount is provided further upstream thereof. The sensor 25 is connected to a potentiometer 26 that detects the rotation angle of the media ring plate, and the output signal (intake air amount signal) of the potentiometer 26 is the main throttle valve 23.
It is input to the control unit 28 together with the throttle opening signal and the engine rotation speed signal S of the throttle opening sensor 27 that detects the opening of the.

On the other hand, the auxiliary intake system 21 has an upstream end located downstream of the air flow sensor 25 in the main intake passage 22 and a main throttle valve 23.
An auxiliary intake port 29a, which is in communication with the upstream side and serves as a downstream end, is constituted by an auxiliary intake passage 29 opened to the combustion chamber 1a of the engine 1. The auxiliary intake passage 29 is driven in the engine 1 via an electromagnetic clutch 9 in the middle thereof. An air pump 7 that is connected and whose drive is turned on and off according to the load of the engine 1 is provided. Further, downstream of the air pump 7 in the auxiliary intake passage 29 is connected to the main throttle valve 23 via an interlocking control mechanism 30 controlled by the control unit 28, and the main throttle valve 23 reaches a set opening. An auxiliary throttle valve 31 is provided which remains closed during low load operation of the engine until it is opened, and opens during high load operation of the engine in which the main throttle valve 23 is opened at a set opening or more.

Further, the auxiliary intake system 21 is provided with a communication passage 32, one end of which opens downstream of the air pump 7 in the auxiliary intake passage 29, upstream of the auxiliary throttle valve 31, and the other end opens upstream of the auxiliary intake passage 29 in the air pump 7. A relief valve 33 is provided in the communication passage 32, and when the pressure (supercharging pressure) in the auxiliary intake passage 29 downstream of the air pump 7 becomes equal to or higher than a set pressure when the air pump 7 is operating (supercharging). Relief valve 3 above
By the opening operation of 3, the pressure is released to the auxiliary intake passage 29 upstream of the air pump 7 through the communication passage 32, and the supercharging pressure is maintained at the set pressure. Further, the relief valve 33 is controlled by the control unit 28 to variably control the relief pressure of the relief valve 33 to control the supercharging pressure control solenoid 34.
Is connected, the relief valve 33 is substantially opened when the supercharging is not performed due to the non-actuation of the air pump 7 and the relief valve 33 is substantially opened. The control valve 11 is configured such that the relief pressure is maintained at a set value so as to be substantially closed.

Furthermore, the main intake valve 35 is attached to the main intake port 22a.
However, the auxiliary intake valve 36 is also attached to the auxiliary intake port 29a.
The respective intake valves 35 and 36 are arranged such that the valve timings of the both intake valves 35 and 36 are such that the auxiliary intake valve 36 partially overlaps and opens from the final opening of the main intake valve 35, that is, the latter half of the intake stroke to the compression stroke. It is set. From the viewpoint of preventing backflow of intake air to the ports 22a and 29a, it is preferable to set the auxiliary intake valve 36 to open after the main intake valve 35 is closed without overlapping, that is, in the compression stroke. .

Due to the above, in the low load operation range of the engine, the main intake system 2
While the air-fuel mixture is supplied to the engine 1 by natural suction from 0 (main intake passage 22), in the high load operation range of the engine,
In addition to the air-fuel mixture from the main intake system 20, a so-called partial supercharging system configured to supply the engine 1 with pressurized air from the operation of the air pump 7 from the auxiliary intake system 21 (auxiliary intake passage 29) at least in the compression stroke. Has been done. In addition, 37 is a valve operating mechanism for controlling the valve timing of the auxiliary intake valve 36, 38 is an exhaust port, 39 is an exhaust valve disposed in the exhaust port 38, and 40 is an intercooler for cooling the supercharger.

Also in the case of this example, the control unit 28
Thus, when the drive start load of the air pump 7 is set to a plurality of stages, and the drive start load of the air pump 7 is set to a high speed stage when the transmission is set to a low speed stage. The load is set to be higher than that of the first embodiment, and the same operational effect as that of the first embodiment is obtained.

As described above, according to the engine supercharging control device of the present invention, the drive start load of the air pump is set to the high speed stage when the transmission is set to the low speed stage. Since it is set to a higher load side than when it is on, when the transmission is set to a high speed stage where high output is required, the supercharging effect is obtained from the lower load range and the output characteristics are improved. In addition, when the low speed stage with good acceleration (blow-up) is set, supercharging is performed only in the high load range to ensure good acceleration performance in the low speed stage. Since the supercharging action by the air pump is not performed until the load reaches the prescribed load to start driving the air pump, unnecessary driving of the air pump is avoided during slow driving, where low speed / low load running is performed at low speed stages, and reliability of the air pump is avoided. To improve The effect that can be obtained is obtained.

[Brief description of drawings]

The drawings illustrate an embodiment of the present invention, FIG. 1 is an overall schematic system diagram showing the first embodiment, FIG. 2 is a control characteristic diagram of the air pump and control valve shown in FIG. 1, and FIG. FIG. 4 is a torque curve diagram showing the drive start load of the air pump for each gear,
FIG. 5 is a control flowchart of the control unit. FIG. 6 is an overall schematic system diagram showing the second embodiment. 1 ... Engine, 2 ... Intake passage, 7 ... Air pump, 8 ... Control unit, 10 ... Communication passage, 11 ... Control valve, 1
7 ... Drive start load setting means, 22 ... Main intake passage, 28 ...
Control unit, 29 ... Auxiliary intake passage, 32 ... Communication passage.

Claims (1)

[Claims] 1. An air pump driven by the engine and turned on / off according to the load of the engine, in the middle of an intake system passage of the engine connected to an external load via a transmission, and a suction of the air pump. A communication passage that communicates the air supply side and the discharge side by bypassing the air pump, and a control valve that opens and closes the communication passage according to the load of the engine, and closes the control valve when the air pump is driven. In the supercharging control device for the engine described above, the drive start load of the air pump is set to a plurality of stages, and the drive start load of the air pump is set to a high speed stage when the transmission is set to a low speed stage. The engine supercharging control device is provided with a drive start load setting means for setting the load so as to be on a higher load side than when it is set to.