JPH057538B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a boost pressure control system for an engine equipped with an engine-driven rotary displacement supercharger such as a Roots blower.

[Related technologies and problems]

A supercharger, such as a Roots blower, is driven by the engine via an electromagnetic clutch. The intake system is provided with a bypass, similar to the supercharger, and this bypass is opened and closed by a bypass control valve. The engine is supercharged by connecting the electromagnetic clutch, rotating the supercharger, and closing the bypass.

This type of engine-driven supercharger has better supercharging response than an exhaust turbo supercharger, so
Although it has the advantage of being able to quickly increase the engine output during sudden acceleration, it has the problem that the supercharging pressure rises rapidly at the start of supercharging, resulting in shock or knocking.

Another problem with the design of this type of supercharger is that the electromagnetic clutch is not sufficiently durable.
The electromagnetic clutch is connected when the engine load exceeds a set value. The applicant previously proposed a boost pressure control device that switches the load judgment value for electromagnetic clutch connection between high altitude and flat land, and connects the electromagnetic clutch with a light load at high altitude (January 1985). Special request on the 13th
61-3639). This is aimed at increasing torque at high altitudes through supercharging in response to changes in throttle opening, reducing the amount of accelerator depression required to improve drivability, and reducing the frequency of power increase use. However, on the other hand, at high altitudes, the frequency of turning the electromagnetic clutch on and off increases, which accelerates the wear of the electromagnetic clutch and has a negative impact on its durability. Additionally, the electromagnetic clutch remains on for a longer period at high altitudes than at flatlands, which worsens fuel efficiency.

[Purpose of the invention]

The present invention aims to solve the above-mentioned problems, alleviate the supercharging shock, improve the durability of the electromagnetic clutch, and improve fuel efficiency.

[Means and actions for solving problems]

As shown in FIG. 1, the supercharging pressure control device of the present invention includes a rotary positive displacement supercharger for supercharging an internal combustion engine in the intake system, and has an input pulley driven by the engine. The turbocharger is configured to be driven via an electromagnetic clutch, and the intake system is provided with a bypass for the turbocharger, and the bypass is configured to be opened and closed by a bypass control valve. In an internal combustion engine with a supercharger that connects an electromagnetic clutch before closing, a high-altitude determination means for determining whether the vehicle is running on a highland, a load detection means for detecting an engine load, and a high-altitude determination means for determining whether or not the vehicle is traveling on a highland, and a load detection means for detecting an engine load, and a an electromagnetic clutch control means for connecting the electromagnetic clutch when a load determination value of The present invention is characterized in that the load determination value is set larger at high altitudes than at flatlands, and the closing speed of the bypass control valve is switched in accordance with the required acceleration.

On flat terrain where the density of intake air is high and the torque increase due to supercharging is large, the electromagnetic clutch is connected at light loads, so the supercharging shock is suppressed.

At high altitudes, where the air density is low and the torque increase due to supercharging is small, the electromagnetic clutch is connected under a higher load than at flatlands, so it is difficult to turn the electromagnetic clutch ON/OFF.
frequency decreases. Further, the closing speed of the bypass control valve is changed according to the required acceleration, and when the acceleration is small, supercharging is started slowly, so there are few supercharging shocks.

〔Example〕

Referring to FIG. 2, the intake system of the engine 10 consists of an air cleaner 12, an intake passage 14, an air flow meter 16, a throttle valve 18, etc.
The fuel supply system includes an electronically controlled fuel injection valve 20. The intake passage 14 is provided with a supercharger 22 consisting of a Roots blower and a bypass 24. The supercharger 22 is connected to the engine 10 via an electromagnetic clutch 26.
Power is transmitted from the crank pulley 32 to the input pulley 28 of the electromagnetic clutch 26 via a transmission belt 30. When the electromagnetic clutch 26 is connected while the engine is running, the supercharger 22
pumps intake air, but before the bypass 24 closes, the supercharger escapes to the suction side of the supercharger 22 via the bypass 24, so the engine is not supercharged. The electromagnetic clutch 26 is controlled on/off by an engine control computer (ECU) 34 consisting of a microcomputer. The throttle valve 18 is linked to a throttle sensor 36 that detects the throttle opening, and its analog output is input to the ECU 34. The output signal of the air flow meter 16 is also
Sent to ECU34. The output signal from the crank angle sensor 35 is sent to the ECU 34 and used to detect the engine speed.

Bypass 24 is opened and closed by bypass control valve 38. The control valve 38 includes a movable valve body 40 that opens and closes the bypass 24, a diaphragm 42 that interlocks with the valve body 40, a pressure chamber 44 and an atmospheric pressure chamber 46 separated by the diaphragm 42, and a return spring 48. The pressure chamber 44 is connected to an outlet port 52 of an electromagnetic switching valve 50. This switching valve 5
0 has two inlet ports 54, 56, either of which can be selectively connected to the outlet port 52.
It seems that it is connected to. That is, ECU34
When the switching valve 50 is energized, the second inlet port 56 is connected to the outlet port 52, and when the energization is stopped, the first inlet port 54 is connected to the outlet port 52.
connected to.

The intake passage 14 is provided with an atmospheric pressure port 58 upstream of the throttle valve 18, and this atmospheric pressure port 58 is connected to the second switching valve 50 by a conduit 60.
Connected to inlet port 56. Further, the intake passage 14 is provided with a signal port 62 downstream of the throttle valve 18 to take out intake pipe pressure. As is well known, the intake pipe pressure at the signal port 62 becomes negative pressure when the opening degree of the throttle valve 18 is small, and approaches atmospheric pressure as the throttle opening degree increases. This signal port 62 is connected to the first inlet port 54 of the switching valve 50 by a line 64 with a negative pressure delay device 63.

According to the above configuration, when the electromagnetic switching valve 50 is energized, the atmospheric pressure of the atmospheric pressure port 58 is applied to the pressure chamber 44 of the bypass control valve 38, and the control valve 38 is closed. When the power supply is stopped, the intake pipe pressure of the signal port 62 is applied to the pressure chamber 44, but in this case, the intake pipe pressure changes according to the throttle opening as described above, so when the throttle opening is small and the load is light, Negative pressure is applied to the pressure chamber 44, the bypass control valve 38 opens, and the bypass 24 is released. When the throttle opening is large and the load is high, the pressure chamber 44 is supplied with negative pressure close to atmospheric pressure via the negative pressure delay device 63. is applied, the bypass control valve 38 gradually closes, and the bypass 24 is slowly closed.

As shown in FIG. 3, the ECU 34 includes a central processing unit (CPU) 66, a read-only memory (ROM) 68, a random access memory (RAM) 70, and an A/D converter 7.
2, has a conventional configuration consisting of an input interface 74, an output interface 76, and a bus 78.

A control routine program and necessary data, which will be described later with reference to the flowchart in FIG. 4, are stored in the ROM 68 in advance, and by executing this program, the boost pressure control device of the present invention is realized. . A/D converter 72 is CPU6
6, the signals from the air flow meter 16 and the throttle opening sensor 36 are converted into binary numbers, and the binary data representing the intake air amount and the throttle opening is stored in the RAM 70 and used for calculations described later. The altitude sensor 80 is composed of, for example, a bellows type sensor, which outputs an "OFF" signal when the atmospheric pressure is equivalent to the level ground, and outputs an "ON" signal when the atmospheric pressure is equivalent to the high ground, and the CPU 66 can read this signal at any time. . Crank angle sensor 35
The output pulse is sent to the input interface 74, and the CPU 66 calculates the engine speed based on this output pulse in a well-known manner and uses the data.
Store in RAM70.

Next, referring to the flowchart in Figure 4,
The operation of the ECU 34 will be explained. This routine 10
By executing step 1, the supercharging pressure is controlled. step
102, the engine 1 is calculated based on the intake air amount Q detected by the air flow meter 16 and the engine rotation speed NE detected by the crank angle sensor 35.
Take in the intake air amount Q/N per rotation. This Q/
The N value is used to represent engine load. In step 103, it is determined whether the terrain is flat or high based on the signal from the altitude sensor 80. If the terrain is flat, the process proceeds to step 104, and if the area is high, the process proceeds to step 111.

First, the case where it is determined that the terrain is flat and the process proceeds to step 104 will be explained. In step 104, the engine load is determined by determining whether or not the actually measured Q/N is larger than a set value A (for example, 0.4 l/rev). If the load is high, the electromagnetic clutch 26 is connected in step 105 to start the supercharger 22, and the electromagnetic switching valve 50 is turned on in step 109. As a result, the atmospheric pressure of the atmospheric pressure port 58 is applied to the pressure chamber 44 of the bypass control valve 38, so the valve body 40 closes the bypass 24 and the engine is supercharged. Next, in step 120, the main routine is returned.

If it is determined in step 104 that the load is low, the process proceeds to step 106, where it is determined whether the delay time _T2 is greater than a set value (for example, 10 seconds). This delay time _T2 represents the time elapsed since the Q/N became below the set value, and is 10
Before the second elapses, the electromagnetic clutch 26 changes from ON to OFF.
Prohibits switching to the state and prevents the electromagnetic clutch from frequently
This is to prevent it from being turned on/off. If it is determined in step 106 that 10 seconds have not yet elapsed, the electromagnetic clutch continues to be connected in step 108.
Proceed to step 110 and turn off the solenoid valve 50. As a result, the pressure chamber 44 of the bypass control valve 38 is connected to the signal port 62, and negative pressure is applied to the intake pipe, so that the bypass 24 is opened. Therefore, in this state, the supercharger 22 is rotating but the engine is not supercharged.

If it is determined in step 106 that the delay time of 10 seconds has elapsed, the process proceeds to step 107 and the electromagnetic clutch 2 is
After turning off the solenoid valve 50, turn off the solenoid valve 50 in step 109.
Turn it on. As a result, the bypass 24 is closed and the intake air is drawn into the engine via the supercharger 22, so the supercharger 22 is forced to idle by the intake air flow. The reason for idling in this manner is that the rotational speed difference between the input pulley 28 and the supercharger rotor is small, and wear is minimized when the electromagnetic clutch is next connected.

Next, a case will be described in which it is determined in step 103 that the area is at a high altitude and the process proceeds to step 111. step
At step 111, the engine load is determined by determining whether Q/N is larger than the second set value B.
This set value B is set larger than the set value A, and is, for example, 0.5l/rev. Q/N＞0.5l/
In the case of rev, the process advances to step 112 and the electromagnetic clutch is connected. In this way, in steps 104 and 111, ON/OFF control of the electromagnetic clutch 26 is performed based on each set value A and B, but since set value B is set larger than set value A, , the electromagnetic clutch will be connected at a lower load in a flat area than at a high altitude, and conversely, it will be connected at a higher load at a high altitude than at a flat area. In this way, since the electromagnetic clutch is connected at a lower load on flat ground, the supercharging shock is alleviated accordingly. In addition, at high altitudes, the electromagnetic clutch is engaged under a higher load, which reduces the frequency of on/off operations and reduces wear on the clutch.

After step 112, the process proceeds to step 113. In step 113, the throttle opening speed change ΔTA obtained from the output from the throttle sensor 36 is taken. This ΔTA is used in the next step 114 as representing the required acceleration. In step 114, △TA is compared with a set value (for example, 1.46°/16ms), and if △TA>1.46°/16ms, it is a sudden acceleration condition, so in step 118, the solenoid valve 50 is turned on.
This quickly closes the bypass 24 and immediately starts supercharging. A supercharging shock will then occur, but this will be tolerated under conditions of rapid acceleration.
During slow acceleration when △TA is smaller than the set value, step
Proceed to step 119 and turn off the solenoid valve 50. As a result, the pressure chamber 44 of the bypass control valve 38 is connected to the signal port 62 and the near atmospheric pressure at the signal port 62 is introduced into the pressure chamber 44 via the line 64, but not in the line 64. is a negative pressure delay device 63
Since the pressure transmission is delayed due to the provision of the bypass control valve 38, the bypass control valve 38 gradually closes. Therefore, the supercharging pressure increases relatively slowly, so that the supercharging shock is relaxed. In this way, even if the load increases at high altitudes, under conditions where acceleration is small, supercharging shock does not occur.

If it is determined in step 111 that the Q/N is smaller than 0.5l/rev, the process proceeds to step 115, where it is determined whether the delay time T ₁ (same as T ₂ above) is larger than the set value (for example, 5 seconds). Determine whether or not. If the delay time has not yet elapsed, the solenoid clutch continues to be connected in step 116, and the solenoid valve 50 is closed in step 119.
Turn it OFF and open the bypass 24. When the delay time has elapsed, the electromagnetic clutch is turned OFF in step 117, and the process proceeds to step 119. In this state, the engine is not supercharged.

In the above embodiment, it was explained that the determination of high ground and flat ground is made based on a certain altitude.
More than one determination value may be used, and the electromagnetic clutch connection conditions may be changed accordingly.

Further, as shown in FIG. 5, the load determination value for connecting the electromagnetic clutch may be gradually changed depending on the altitude.

Further, in the embodiment, the determination of high altitude is described as being performed using an altitude sensor, but the determination may also be made using a learned value of the air-fuel ratio.

〔Effect of the invention〕

Generally, on flat ground with high air density, the torque increase due to supercharging is large and a supercharging shock occurs. In the present invention, since the electromagnetic clutch 26 is connected and supercharging is started at a lighter load on flat ground, the supercharging shock can be reduced and the operating performance is improved.

On the other hand, at high altitudes where air density is low and therefore large supercharging shocks do not occur, the electromagnetic clutch is connected under a higher load than at flatlands, so the frequency of turning the electromagnetic clutch on and off is reduced. Therefore, wear on the electromagnetic clutch is reduced and durability is improved.
Furthermore, since the power loss required to rotate the supercharger is reduced, the fuel consumption rate is improved.

Furthermore, at high altitudes, even if the engine load increases, the bypass control valve 38 closes slowly under conditions where the acceleration is small and the supercharging pressure gradually increases, so that no supercharging shock occurs.

[Brief explanation of the drawing]

FIG. 1 is a functional block diagram of the boost pressure control device of the present invention, FIG. 2 is a schematic diagram of a supercharged engine to which the device of the present invention is applied, and FIG. 3 is a block diagram of an engine control computer. FIG. 4 is a flowchart of the boost pressure control routine, and FIG. 5 is a map showing one aspect of the load determination value. 10... Engine, 14... Intake passage, 22... Supercharger, 24... Bypass, 26... Electromagnetic clutch, 38
...Bypass control valve, 50...Solenoid switching valve.

Claims (1)

[Claims] 1. A rotary displacement supercharger designed to supercharge an internal combustion engine is provided in the 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 of the supercharger, and the bypass is opened and closed by a bypass control valve, and during supercharging, an electromagnetic clutch is connected before closing the bypass control valve. In a supercharged internal combustion engine, a high altitude determination means determines whether the vehicle is traveling on a highland, a load detection means detects an engine load, and the electromagnetic clutch is activated when the engine load exceeds a predetermined load determination value. an electromagnetic clutch control means for connecting an electromagnetic clutch, an acceleration detection means for detecting a required acceleration, and a bypass control valve control means for controlling a bypass control valve according to the required acceleration, and the load judgment value is set to be larger at high altitudes than at flatlands. A supercharging pressure control device characterized in that the closing speed of the bypass control valve is also switched according to the required acceleration.