JPH0751896B2 - Supercharger control device for internal combustion engine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to control of a supercharger for an internal combustion engine, and more particularly to a controller for a rotary positive displacement supercharger such as a roots blower.

[Prior art and problems]

Unlike exhaust turbochargers, Roots blowers and other rotary positive displacement turbochargers are driven by the power of the engine. Therefore, the power of the engine is transmitted from the crank pulley to the input pulley of the electromagnetic clutch via the belt transmission device or the like, and the supercharger is rotated by connecting the electromagnetic clutch. A bypass of the supercharger is provided in the intake system, and this bypass is opened and closed by a bypass control valve.

Since supercharging is required when the engine is heavily loaded, when the load reaches a preset value, the electromagnetic clutch is first connected to rotate the supercharger (for example, Japanese Utility Model Laid-Open No. 59-110330).
When the load further increases and exceeds the second set value, the bypass is closed and supercharging is started.

At high altitudes, the atmospheric pressure is low and the density of intake air is low, so the absolute amount of intake air that fills the engine decreases. For this reason, as compared with the case of traveling on a flat ground, the output on a level ground level cannot be obtained unless the accelerator pedal is further depressed in a highland and the throttle opening is made larger than the level ground.
However, in today's engines, in order to suppress exhaust emissions and save fuel, the air-fuel ratio is feedback-controlled toward the stoichiometric air-fuel ratio during steady running with a small throttle opening, but with a large throttle opening acceleration. At times, this is called power increase so that the air-fuel ratio can be increased to ensure the required output. Therefore, as described above, when the number of traveling modes with a large throttle opening in the highlands increases, the frequency of use of the power increase increases even though the large output is not originally required, and there is room for improvement in the fuel consumption rate. .

Further, in order to travel at high altitude with the same acceleration as on flat ground, it is necessary to increase the amount of depression on the accelerator pedal, which deteriorates driving performance.

In a vehicle equipped with an automatic transmission, it has been previously proposed to switch the operating range of the supercharger in accordance with the shift pattern of the transmission (Japanese Patent Application No. 60-
No. 141516 and Japanese Patent Application No. 60-filed on July 1, 1985
142421), these techniques do not solve the above problems.

[Object of the Invention]

An object of the present invention is to further improve the performance of an internal combustion engine equipped with a rotary positive displacement supercharger, to reduce the frequency of use of power increase of air-fuel ratio at high altitude, and to improve the operation feeling of the accelerator pedal. Intended to improve.

[Means for solving problems]

According to the present invention, a rotary positive displacement supercharger adapted to supercharge an internal combustion engine is provided in an intake system, and the supercharger is driven via an electromagnetic clutch having an input pulley driven by the engine. However, a supercharger bypass is provided in the intake system, and the bypass is configured to be opened and closed by a bypass control valve.When supercharging, an electromagnetic clutch is connected before closing the bypass control valve. A turbocharger control device is provided for an internal combustion engine with a motor. As shown in FIG. 1, this control device has a highland determining means for determining whether or not a vehicle is traveling in a highland, a load detecting means for detecting an engine load, and an engine load exceeding a predetermined load determination value. An electromagnetic clutch control means for connecting the electromagnetic clutch is sometimes provided, and the load determination value is set to be small at high altitudes.

〔Example〕

Referring to FIG. 2, the intake system of the engine 10 includes an air cleaner 12, an intake passage 14, an air flow meter 16, a throttle valve 18, etc., and a fuel supply system is an electronically controlled fuel injection valve.
Comprising 20. A supercharger 22 and a bypass 24 are provided in the intake passage 14. In the illustrated embodiment, the supercharger 22 is composed of a roots blower, but a scroll pump, a vane pump, or other rotary positive displacement pump may be used. The supercharger 22 is driven by the engine 10 via the conventional electromagnetic clutch 26, and power is transmitted from the crank pulley 32 to the input pulley 28 of the electromagnetic clutch 26 via the transmission belt 30. Electromagnetic clutch 26 while engine is running
, The supercharger 22 pumps intake air, but before the bypass 24 closes, the supercharger passes through the bypass 24 and the supercharger 22
Since it flows back to the suction side of, supercharging is not performed. The on / off control of the electromagnetic clutch 26 is performed by an engine control computer (ECU) 34 including a microcomputer as described later. Therefore, the outputs from the air flow meter 16, the throttle opening sensor 36, the crank angle sensor 38, and the altitude sensor 40 are sent to the ECU 34.

The bypass 24 is opened and closed by the bypass control valve 42. The operating pressure to the control valve 42 is obtained from the signal port 44 of the intake passage 14 and is switched by the electromagnetic three-way valve 46, and the electromagnetic valve 46 is on / off controlled by the ECU 34. The solenoid valve 46 has its inlet port connected to the pipe line 48 when energized, and is connected to the pipe line 52 with the check valve 50 when not energized. When the throttle valve 18 has a small opening and a light load, a negative pressure acts on the signal port 44, and this negative pressure is transmitted via the check valve 50 to the bypass control valve.
Since it is transmitted to the working chamber of 42, the control valve 42 is opened and the bypass 24 is opened. Therefore, supercharging is not performed even if the supercharger 22 is rotating. When the throttle opening increases as the engine load increases, the pressure at the signal port 44 approaches atmospheric pressure, but unless the solenoid valve 46 is energized, a negative pressure is generated in the working chamber of the control valve 42 by the action of the check valve 50. Since it is maintained, the control valve 42 is maintained in the open state. When the solenoid valve 46 is energized, the atmospheric pressure of the signal port 44 is applied to the working chamber of the control valve 42 via the line 48, the bypass 24 is closed, and the engine is supercharged.

As shown in FIG. 3, the ECU 34 includes a central processing unit (CPU) 54, a read only memory (ROM) 5
6, random access memory (RAM) 58, A / D converter 6
0, input interface 62, output interface 6
4. It has a conventional structure consisting of a bus 66. The ROM 56 stores in advance a program for a control routine and necessary data, which will be described later with reference to the flowchart in FIG. 4, and the supercharger control device of the present invention is realized by executing this program. The A / D converter 60 converts the signals from the air flow meter 16 and the throttle opening sensor 36 into a binary number in accordance with a command from the CPU 54, and the binary number data representing the intake air amount and the throttle opening is stored in the RAM 58 and used for the later-described calculation. used. The altitude sensor 40 is composed of, for example, a bellows type sensor, which outputs an “OFF” signal when the atmospheric pressure is equivalent to a flatland and an “ON” signal when the atmospheric pressure is equivalent to a highland.
Can read this signal at any time. The output pulse of the crank angle sensor 38 is sent to the input interface 62, and the CPU 54 calculates the engine speed based on the output pulse in a known manner and stores the data in the RAM 58.

FIG. 4 shows a flow chart of the supercharger control routine. The operation of the control routine can be more easily understood by first explaining the principle of the control device of the present invention with reference to FIG. . The graph of FIG. 5 shows the fluctuation of the engine torque with respect to the change of the throttle opening,
A thin curve A shows a torque fluctuation when the engine is not supercharged, and a thin curve B shows a torque fluctuation when the engine is supercharged. The torque fluctuations due to the conventional control device are shown by the thick dashed curve C. That is, in the highlands, when the throttle opening reaches TA ₁ , the air-fuel ratio power is increased, and when reaching TA ₂ , supercharging is started at point E and the torque approaches curve B. Therefore, in the conventional device, in order to obtain the torque T at high altitude, it is necessary to increase the power and increase the throttle opening to TA ₃ .

The present invention intends to obtain the same torque T at high altitude while reducing the throttle opening without increasing the power. As shown by a thick solid curve D,
It is based on the idea of starting supercharging at point F where the throttle opening is smaller. That is, the supercharging is started at the throttle opening TA ₄ , the torque approaches the curve B, and the desired torque T is obtained at the point G. Therefore, the amount of power is not increased, and the throttle opening is smaller than before.

The supercharger control routine of FIG. 4 is designed on the basis of such a principle, and this routine can be executed as an interrupt routine of the main routine executed by the ECU 34, for example, every 100 milliseconds. In step 101, the engine speed NE calculated based on the signal from the crank angle sensor 38 and the intake air amount Q converted based on the output from the air flow meter 16 are read, and in step 102, the engine is calculated based on these data. Calculate the intake air amount Q / N per revolution. This Q / N value is used in the later-described judgment as representing the engine load.

Next, in step 103, it is determined whether or not the vehicle traveling place is a highland, and if it is a flatland, the process proceeds to step 106, and if it is a highland, the process proceeds to step 104. The altitude determination in this step 103 is performed based on the output of the altitude sensor 40, but when learning control of the altitude is performed in the control routine of the electronically controlled fuel injection device, it is used to determine whether or not the altitude is high. Good.

When it is determined that the altitude is high in the determination in step 103, it is determined in step 104 whether the intake air amount Q / N (which represents the load) is larger than a first set value (for example, 0.3 / rev), If it is determined to be flat ground, it is determined in step 109 whether or not the intake air amount Q / N is larger than a second set value (for example, 0.5 / rev). If the determination result of step 104 or step 109 is "NO" (that is, if the intake air amount Q / N representing the load is smaller than the first and second set values), the electromagnetic clutch 26 is turned on in step 112. The bypass 24 is opened by turning off the solenoid valve 46 in step 113 to stop the energization of the solenoid valve 46, and the process returns to the main routine in step 108.

When the determination result of step 104 or step 109 is "YES" (that is, when Q / N representing the load is larger than the respective set values), the process proceeds to step 105 and step 110, respectively, and the electromagnetic clutch 26 is engaged. . As a result, the supercharger 22 is rotated, but supercharging is not performed before the bypass control valve 42 is closed.

It should be noted here that in the case of high altitude, the first set value used for load determination in step 104 (for example, 0.3 / re
v) and the second set value (for example, 0.5 / rev) used for the load determination in step 109 in the case of flat ground is the first set value <
That is, it is set in relation to the second set value. That is,
In the case of high altitude, the electromagnetic clutch is connected with a smaller load (and therefore smaller throttle opening) than in the case of flat ground,
The supercharger is activated.

After connecting the electromagnetic clutch, step 10
At 6, the intake air amount Q / N is the third set value (eg 0.4 / re
v) It is determined whether or not it is larger, and in the case of flat land, Q / N is the fourth established value (eg, 0.6 / rev) in step 111.
If it is larger, the process proceeds to step 113 to open the bypass, and if it is larger, the process proceeds to step 107 to close the bypass. Supercharging of the engine is started by closing the bypass 24. Here again, the set value for determining the bypass opening / closing condition, that is, the third set value (for example, 0.4 / rev) in the case of highland and the fourth set value (for example, 0.6 / rev) in the case of flatland are There is a relation of the third setting <the fourth setting value. Therefore, in the highland, supercharging is started with a smaller load than in the flatland, and as described above with reference to FIG. 5, a smaller throttle opening (point F in FIG. 5) in the highland. The supercharging starts in.

In the above-described embodiment, the supercharger operating condition is switched between the flatland and the highland regardless of the gear position of the transmission of the vehicle, but in the case of a vehicle with a manual transmission, a high gear that does not require high output is used. The supercharger operating conditions may be switched as described above only when in use, and in the case of a vehicle with an automatic transmission, only when the economical traveling shift pattern is selected.

〔The invention's effect〕

As described above with reference to FIG. 5, according to the present invention, the engine is supercharged with a smaller throttle opening than in the past in the highland, so that the frequency of power increase is significantly reduced. Therefore, fuel consumption can be reduced.

Further, since it is not necessary to increase the throttle opening degree in order to obtain a desired output at high altitude, the accelerator operation feeling is improved and the driving performance is improved.

[Brief description of drawings]

1 is a functional block diagram of a supercharger control device of the present invention, FIG. 2 is a schematic diagram of an engine with a supercharger to which the device of the present invention is applied, FIG. 3 is a block diagram of an engine control computer, FIG. 4 is a flowchart of a supercharger control routine, and FIG. 5 is a graph showing torque fluctuation with respect to a change in throttle opening. 14 …… intake passage, 22 …… supercharger, 24 …… bypass, 26 …… electromagnetic cutic, 28 …… input pulley, 34 …… engine control computer, 40 …… altitude sensor.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Naohide Izumiya 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Co., Ltd. (56) Reference JP-A-56-167817 (JP, A) JP-A-59-82527 (JP, A)

Claims (1)

[Claims] 1. A rotary positive displacement supercharger adapted to supercharge an internal combustion engine is provided in an intake system, and the supercharger is driven via an electromagnetic clutch having an input pulley driven by the engine. The intake system is provided with a bypass for a supercharger, and the bypass is opened and closed by a bypass control valve.When supercharging, an electromagnetic clutch is connected before closing the bypass control valve. In an internal combustion engine with a feeder, a highland determination means for determining whether or not the vehicle is traveling in a highland, a load detection means for detecting an engine load, and the electromagnetic clutch are connected when the engine load exceeds a predetermined load determination value. An electromagnetic clutch control means for controlling the supercharger control device, wherein the predetermined load value is set to be small at a high altitude.