JP2015047884A - Internal combustion engine for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten compressor stop time in a case where a compressor of an air conditioner is stopped to restore a negative pressure, when a brake negative pressure drops to a limit value or less in idling rotation state.SOLUTION: When braking becomes off under a condition where an intake negative pressure P is less than a reference value P2, an air conditioner is cut, and at the same time, an intake amount is throttled to a provisional air amount Q2 which is less than a normally required air amount Q0 and more than an absolute air amount which is required for combustion. Thus, an intake negative pressure can be quickly recovered. When the intake negative pressure reaches a required negative pressure P0 or a throttling time of a provisional air amount Q3 reaches a limit time T2, a required air amount is supplied by increasing an open degree of a throttle valve 11. When the intake negative pressure P reaches the required negative pressure P0, the open degree of the throttle valve 11 is returned and driving of the air conditioner is resumed.

Description

  The present invention relates to an internal combustion engine with an air conditioner for driving a brake booster with an intake negative pressure.

  Since the brake of a vehicle cannot secure a necessary braking force only by the force of a person's foot, a brake booster that amplifies the stepping force is provided, and an intake negative pressure is generally used as a power source of the brake booster. However, in a low rotation region such as an idle rotation region, the pumping action of the piston is weak and the intake pressure is low (that is, the degree of vacuum is low), so that the negative pressure required for driving the brake booster may be insufficient.

  In this case, it can be said that the rotational speed is increased and the negative pressure of the intake system is increased to the vacuum side, but simply increasing the rotational speed results in poor fuel consumption. Therefore, since the compressor of the air conditioner is often driven by the rotational power of the crankshaft, when operating the air conditioner, the intake air negative pressure is reduced by stopping the drive of the air conditioner compressor and increasing the rotation speed. Raising is done.

  As an example, Patent Document 1 discloses that in a configuration in which a compressor is stopped on the condition of a vehicle deceleration rate or the like, the compressor stop time is increased as the intake negative pressure is decreased. On the other hand, in Patent Document 2, considering that there is a time lag from when the compressor is stopped until the negative pressure actually recovers, the brake negative pressure recovery value is taken into account by taking into account the delay in response to brake negative pressure recovery. It describes that the load of an auxiliary machine such as a compressor is limited from the point of time when the negative pressure is high, and that the auxiliary restriction of the auxiliary machine is released when the brake negative pressure is restored.

JP 2003-276416 A JP 2010-221894A

  When the compressor of the air conditioner is stopped driving, the temperature of the wind blowing into the vehicle rises, so the comfort in the vehicle decreases. In addition, when the temperature rise time is short, there are many cases where the passenger does not notice, but when the temperature rise time becomes long to some extent, this may be noticed, and there is a fear that the air conditioner may be out of order.

  Therefore, it is preferable that the air conditioner cut time is as short as possible. However, in both Patent Documents 1 and 2, the air conditioner cut time cannot be further shortened if the intake negative pressure is lowered to the lowest line. In particular, in the case of Patent Document 2, since the air conditioner is cut in a state where the negative pressure is high, the air conditioner cut time has to be long, and the problem of anxiety due to a decrease in comfort and an increase in the blowing temperature appears remarkably. .

  In the case of an AT vehicle, the driver keeps stepping on the brake because the vehicle moves slightly in the idle rotation state with the foot away from the accelerator. Therefore, even when the vehicle is stopped, the negative pressure decreases and the compressor of the air conditioner must be stopped. Although it may not be possible to stop the air-conditioner compressor when stopped, the air-conditioner cut time when stopped is as short as possible to improve comfort and prevent anxiety. It can be said that it should be.

  The present invention has been made to improve the current situation.

  An internal combustion engine of the present invention includes an engine body that drives a compressor of an air conditioner, and an intake system connected to a brake booster, and the negative pressure of the brake booster is reduced in an idle operation range or a low rotation range equivalent thereto. The basic configuration is to stop the driving of the compressor of the air conditioner when the value is less than the value necessary for the brake operation, and resume the driving of the compressor of the air conditioner when the negative pressure of the brake booster recovers to the required pressure.

  And when the internal pressure of the brake booster or the intake system during brake operation becomes smaller than a preset reference value, the internal combustion engine stops driving the compressor of the air conditioner, and reduces the intake amount to the engine body, Control is performed so that the air amount is reduced to a smaller amount than the standard air amount when the compressor of the air conditioner is not driven.

  Now, that the intake negative pressure is large (that is, the degree of vacuum is high) means that the intake amount per unit time and unit volume is small. Therefore, if the intake air amount is reduced in a state where the intake negative pressure is large, the amount of air supplied to the combustion chamber is lower than the amount necessary for combustion, and the engine stall is likely to occur.

  On the other hand, in a state where the intake negative pressure is small (close to atmospheric pressure), the amount of air entering the combustion chamber is large, so that combustion can often be maintained even if the control valve is throttled. Therefore, if the time is short, stable rotation can be maintained while the intake air is throttled (if the throttle time is long, the combustion becomes unstable and the engine is likely to be stalled for some reason).

  In the invention of the present application, it is possible to quickly obtain the negative pressure necessary for driving the brake booster by raising the intake negative pressure to the vacuum side below the normal state while stopping driving the compressor of the air conditioner without causing the engine stall. it can. This can improve the comfort in the car by shortening the stop time of the compressor of the air conditioner in the low speed range such as the idling speed range, and also make the passenger feel anxiety as if the air conditioner is malfunctioning. It is possible to prevent or significantly suppress holding.

1 is a schematic diagram of an internal combustion engine according to an embodiment. It is a graph which shows the example of control. It is a flowchart of a control example.

(1). Outline of Internal Combustion Engine Next, an embodiment of the present invention will be described based on the drawings. First, the outline of the internal combustion engine will be described with reference to FIG.

  The internal combustion engine includes a cylinder block 3 in which a cylinder bore 1 is formed and a crankshaft 2 is rotatably held, a cylinder head 4 fixed to the upper surface of the cylinder block 3, and a cylinder head cover 5 fixed to the cylinder head 4. And an oil pan 6 on the lower surface of the cylinder block 2, and these constitute an engine body.

  An intake manifold 7 is connected to one side surface of the cylinder head 4, and an intake passage 9 starting from an air cleaner 8 is connected to the intake manifold 7. A surge tank 10 connected to the intake manifold 7 and a throttle valve 11 located upstream thereof are inserted in the intake passage 9. A fuel injection injector 12 is provided in the intake manifold 7. The surge tank 10 is provided with an intake pressure sensor (pressure gauge) 13.

  In many cases, an ISC (idle speed control) valve is provided. In this case, the intake air amount can be controlled by the ISC valve. An exhaust manifold 14 is fixed to the other side surface of the cinder head 4, and an exhaust passage 15 is fixed to the exhaust manifold 14.

  One end portion of the crankshaft 2 protrudes outward from one side surface of the cylinder block 3, and the accessory drive pulley 17 is fixed to the protruding portion. The alternator 20 and the compressor 21 of the air conditioner are driven by the belts 18 and 19 wound around the accessory drive pulley 17. The two belts 18 and 19 are displaced in the axial direction of the crankshaft 2. The compressor 21 has a built-in clutch 22 that interrupts power. The alternator 20 and the compressor 21 of the air conditioner can be driven by a common accessory drive belt.

  A refrigerant pipe 23 is connected to the compressor 21 of the air conditioner, and an evaporator 24 is inserted in the refrigerant pipe 23. When air is sent to the evaporator 24 by the fan 25, an endothermic effect is generated when the refrigerant is vaporized. Heat is exchanged with the wind, and the wind becomes cool and blows out into the car. Although a condenser, a receiver, a three-way valve, and the like are interposed in the refrigerant pipe 23, they are omitted in the drawing.

  A rotation detection rotor 26 having a large number of protrusions on the outer periphery is fixed to one end of the crankshaft 2, and a rotation sensor 27 is disposed outside the rotation detection rotor 26. By reading the protrusion of the rotation detection rotor 26 with the rotation sensor 27, the number of rotations and the angular velocity can be detected.

  The vehicle is provided with a stepping brake pedal 28, and the depression force of the brake pedal 28 is transmitted to a brake operation piston (not shown) by a negative pressure type brake booster 29. The brake booster 29 is conventionally known and includes a piston 31 fitted in the piston chamber 30 and a plunger 33 slidably fitted in the valve chamber 32. The piston 31 and the plunger 33 are rods. They are integrally connected at 34 and move in conjunction with the movement of the brake pedal 28.

  An exhaust port 35 is provided at one end of the piston chamber 30 opposite to the valve chamber 32, and the exhaust port 35 is connected to the surge tank 10 through a negative pressure passage 36. The negative pressure passage 36 and the front end portion of the valve chamber 32 near the piston chamber 30 are connected by a relief pipe 37. The other end of the piston chamber 30 and the front and rear portions of the valve chamber 32 are connected by a communication path 38. An air discharge pipe 39 is provided at the rear end of the valve chamber 32. A brake sensor 40 is provided in the vicinity of the brake pedal 28.

  When the brake pedal 28 is depressed, a negative pressure acts on the front chamber of the piston chamber 30 to amplify the depression force. When the foot is released from the brake pedal 28, the brake pedal 28 is retracted by a spring (not shown). Then, the negative pressure to the piston chamber 30 is released, and the brake pedal 28 is retracted with a light force.

  The internal combustion engine includes an ECU (engine control unit) 41 as a control device. The ECU 41 includes a throttle valve 11, a fuel injection injector 12, an intake pressure sensor 13, an alternator 20, a clutch 22 of a compressor 21, and a rotation. The sensor 27 and the brake sensor 40 are electrically connected. That is, a control signal is input to the ECU 41 from the intake pressure sensor 13 and the rotation sensor 23a, and the throttle valve 11, the fuel injection pump 12, the alternator 20, and the clutch 22 of the compressor 21 are controlled to be driven by commands from the ECU 41. The

(2). Example of Control Mode Next, an example of the control mode will be described with reference to FIG. The present embodiment is applied to control in an idle rotation range, and assumes a state in which, for example, an AT vehicle is stepped on while the vehicle is stopped and the brake is released for starting. In this case, the intake air control may be performed by the ISC valve, but in the present embodiment, the intake air amount is controlled by the throttle valve 11. In this embodiment, the value of the intake negative pressure of the brake booster 29 is replaced with the value of the intake pressure sensor 13 provided in the surge tank 10.

  When the actual intake negative pressure P1 is smaller than the required negative pressure P0 when the brake is turned from ON to OFF in the idling rotation range (or when the brake is applied), the brake is turned off. At the same time, the compressor 21 of the air conditioner is stopped to reduce the engine load, and the throttle valve 11 is throttled to reduce the intake air amount from the actual intake air amount Q1, thereby increasing the intake negative pressure to the vacuum side.

  In this case, conventionally, as shown by the dotted line, the throttle amount of the throttle valve 11 is an opening (standard opening) that can supply a required air amount (standard air amount) Q0 that is somewhat higher than the air amount that does not reach the engine stall. In this state, the operation is continued, and when the intake negative pressure reaches the required negative pressure P0, the kit of the throttle valve 11 is returned to the original state (withstands the load of the compressor 21), and the air conditioner The compressor 21 was restarted. However, it may take a long time T1 until the intake negative pressure reaches the required negative pressure P0.

  On the other hand, in this embodiment, when the intake negative pressure is smaller than the preset reference value P2, as in the first embodiment, the opening of the throttle valve 11 is temporarily made smaller than the standard opening ( The air intake amount is supplied by an amount smaller than the normal required air amount (standard shoe air amount) Q0. As a result, the intake negative pressure can be quickly recovered. The provisional air amount Q2 is larger than the absolute air amount necessary for combustion.

  Since the intake amount is large when the intake negative pressure is low, the intake amount does not interrupt the amount essential for combustion even if the throttle valve 11 is temporarily excessively throttled. If the squeezing time is longer than a certain level, combustion may become unstable. Therefore, a limit time T2 is set for the time for which the throttle is made larger than usual, and when the limit time T2 elapses, the throttle valve 11 returns to the opening degree of the standard air amount Q0. When the intake negative pressure reaches the required negative pressure P0, the throttle valve 11 is returned to the original opening to drive the compressor 21 of the air conditioner.

  As can be seen from the comparison in FIG. 2D, since the intake negative pressure can be quickly reduced by temporarily increasing the throttle amount of the throttle valve 11, the time T3 until the intake negative pressure reaches the required negative pressure P0. Is shorter than that T1 of the comparative example, and thereby, the drive stop time of the compressor 21 of the air conditioner can be made shorter than before, which can contribute to the improvement of the comfort in the vehicle.

  When the actual intake negative pressure is larger than the reference value P2 on the vacuum side, the intake negative pressure can be rapidly recovered by narrowing the throttle valve 11 for a short time. Therefore, as shown in the second embodiment, the throttle valve 11 There is no need to oversqueeze.

  The opening degree and time when the throttle valve 11 is excessively throttled can be arbitrarily changed according to conditions. That is, based on the degree of divergence of how much the actual intake negative pressure is away from the reference value, one or both of the throttle amount and time can be increased as the degree of divergence increases. Example 3 in FIG. 2E shows a state in which the aperture time is shortened by reducing the aperture amount compared to Example 1.

  Further, it is possible to control the excessive throttle amount and the excessive throttle time of the throttle valve 11 according to the degree of recovery of the intake negative pressure. That is, when the recovery degree of the intake negative pressure is earlier than the model assumed in advance, the throttle time can be shortened to return the throttle valve 11 to the normal opening Q0. When the degree of recovery is very fast, the original air amount Q1 may be returned to the original air amount Q1 without maintaining the standard air amount Q0.

  Since stable rotation is a necessary condition for the internal combustion engine, even if the intake negative pressure does not recover to the required negative pressure P0, the intake amount increases to the required air amount Q0 when the throttle time reaches the preset time limit T2. Is done. If the rotation sensor 27 detects a decrease in the rotation speed, for example, and determines that a rapid increase in the rotation speed is necessary, the rotation speed is returned to the original opening Q1 or the fuel is increased before reaching the time limit T2. You can increase the number.

  As a specific mode in which the throttle valve 11 is excessively throttled, the throttle valve 11 may be throttled all at once to the provisional opening for supplying the provisional air amount Q2, or may be gradually reduced over a period of time. Further, when the temporary opening is reached, a method of gradually increasing the opening to the opening of the required air amount Q0 without maintaining the state can be adopted.

  In the embodiment, the negative pressure of the brake booster 29 is replaced by the negative pressure of the surge tank 10, but a pressure sensor is provided in an appropriate part of the brake booster 29 such as the piston chamber 30 and the like, based on the value of this pressure sensor. It is also possible to control.

(3). Description of Flow FIG. 3 shows a flowchart of a specific control map. This will be explained. The control system is started by the engine operation. First, it is determined whether or not the engine is idling based on a signal from the rotation sensor 27 (S1). Is determined by the brake sensor 40 (S2).

  When the brake sensor 40 is turned off from ON and it is detected whether the brake 28 is released, it is determined whether or not the actual intake negative pressure P1 is smaller than a preset reference value P2 (S3). When the value is lower than the value P2, the driving of the compressor 21 of the air conditioner is stopped (S4).

  Since the intake negative pressure may suddenly recover due to the cut of the air conditioner, it is determined whether or not the actual intake negative pressure is smaller than a preset safety value after the air conditioner cut (S5). When it is smaller than the value, the opening of the throttle valve 11 is reduced to a temporary opening that is smaller than the required negative pressure opening at the normal idle opening (S6). Thereby, the above-described effect can be obtained. If the actual intake negative pressure is higher than the safe value in S5, the throttle valve 11 is set to the required air amount Q0 because there is no need to squeeze the provisional opening (S10).

  When the throttle valve 11 is throttled to the temporary opening Q2 that is equal to or less than the opening of the required negative pressure Q0 in S6, it is determined whether or not the actual intake negative pressure P has reached the required negative pressure P0 (S7). When the negative pressure P becomes equal to or exceeds P0, the throttle valve 11 returns to the original opening (auxiliary driving allowable opening) (S8), and the driving of the compressor 21 of the air conditioner is resumed.

  If the throttle valve 11 has been throttled to the temporary opening, but the actual intake negative pressure P has not reached the required negative pressure P0, whether or not a predetermined time, which is a time limit for maintaining the temporary opening, has elapsed. When the predetermined time has elapsed (S9), the opening of the throttle valve 11 is changed to a safe opening of the required air amount Q9 (S10), and then the actual intake negative pressure P reaches the required negative pressure P0. (S11), and if P is equal to or exceeds P0, the throttle valve 11 is returned to the original state (S8), and the driving of the compressor 21 of the air conditioner is resumed.

  The embodiment of the present invention has been described above, but the present invention can be embodied in various ways. For example, when driving other auxiliary machines such as an alternator, it is possible to temporarily stop driving of other auxiliary machines or lower the driving rate in addition to stopping driving of the compressor 21 of the air conditioner. . Thereby, the time to reach the required negative pressure can be further shortened.

  The present invention can be embodied in an internal combustion engine mounted on a vehicle equipped with a negative pressure drive type brake booster and an air conditioner. Therefore, it can be used industrially.

2 Camshaft 4 Cylinder head 9 Intake passage 10 Surge tank 11 Throttle valve 13 Intake pressure sensor 21 as an example of intake negative pressure (brake negative pressure) detection means 21 Air conditioner compressor 27 Rotation sensor 28 Brake pedal 29 Brake booster 36 Negative pressure passage 40 Brake sensor 41 ECU as an example of control means

Claims (1)

It has an engine body that drives the compressor of the air conditioner and an intake system connected to the brake booster, and the negative pressure of the brake booster is less than the value required for brake operation in the idle operation range or low rotation range equivalent to this. If the air pressure is insufficient, the drive of the compressor of the air conditioner is stopped, and when the negative pressure of the brake booster recovers to the required pressure, the drive of the compressor of the air conditioner is resumed.
When the negative pressure of the brake booster or intake system during brake operation becomes smaller than a preset reference value, the compressor of the air conditioner is stopped and the intake amount to the engine body is driven to drive the compressor of the air conditioner. Controlled to reduce the amount of air below the standard air amount when not in operation
Internal combustion engine for vehicles.

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